sozu_lib/

https.rs

//! HTTPS proxy entry point.
//!
//! Owns the TLS listener config (rustls), the ALPN-driven post-handshake
//! mux dispatch (`h2` → `ConnectionH2`, `http/1.1` → `ConnectionH1`,
//! neither → reject + `https.alpn.rejected.{unsupported,http11_disabled}`
//! metrics), the SNI binding policy (`strict_sni_binding`), and the
//! listener-update surface called from the command socket. Front-end H2
//! is gated by ALPN here; `cluster.http2` is a backend-capability hint.
//! Frontend rustls handshake I/O lives in `lib/src/protocol/rustls.rs`;
//! certificate resolution lives in `lib/src/tls.rs`.

use std::{
    cell::RefCell,
    collections::{BTreeMap, HashMap, hash_map::Entry},
    io::ErrorKind,
    net::SocketAddr as StdSocketAddr,
    rc::{Rc, Weak},
    str::{from_utf8, from_utf8_unchecked},
    sync::Arc,
    time::{Duration, Instant},
};

use mio::{
    Interest, Registry, Token,
    net::{TcpListener as MioTcpListener, TcpStream as MioTcpStream},
};
use rustls::{
    CipherSuite, ProtocolVersion, RootCertStore, ServerConfig as RustlsServerConfig,
    ServerConnection, SupportedCipherSuite,
    crypto::CryptoProvider,
    pki_types::{CertificateDer, CertificateRevocationListDer, pem::PemObject},
    server::WebPkiClientVerifier,
};
use rusty_ulid::Ulid;
use socket2::SockRef;
use sozu_command::{
    certificate::Fingerprint,
    config::{DEFAULT_ALPN_PROTOCOLS, DEFAULT_CIPHER_LIST},
    listener_key::ListenerKey,
    proto::command::{
        AddCertificate, CertificateSummary, CertificatesByAddress, ClientAuthMode,
        ClientAuthPolicy, Cluster, ForwardedHeaders, HttpsListenerConfig,
        ListOfCertificatesByAddress, ListenerType, RemoveCertificate, RemoveListener,
        ReplaceCertificate, RequestHttpFrontend, ResponseContent, TlsVersion,
        UpdateHttpsListenerConfig, WorkerRequest, WorkerResponse, request::RequestType,
        response_content::ContentType,
    },
    ready::Ready,
    response::HttpFrontend,
    state::{
        ClusterId, validate_alpn_protocols, validate_forwarded_headers,
        validate_h2_flood_knobs_https, validate_sozu_id_header,
    },
};

use crate::metrics::names;
use crate::{
    AcceptError, CachedTags, FrontendFromRequestError, L7ListenerHandler, L7Proxy, ListenerError,
    ListenerHandler, Protocol, ProxyConfiguration, ProxyError, ProxySession, SessionIsToBeClosed,
    SessionMetrics, SessionResult, StateMachineBuilder, StateResult,
    backends::BackendMap,
    crypto::{cipher_suite_by_name, default_provider, kx_group_by_name},
    pool::Pool,
    protocol::{
        Pipe, SessionState,
        http::answers::HttpAnswers,
        http::parser::{Method, hostname_and_port},
        mux::{self, Mux, MuxTls},
        proxy_protocol::expect::ExpectProxyProtocol,
        rustls::TlsHandshake,
    },
    router::{RouteResult, Router},
    server::{ListenToken, SessionManager},
    socket::{FrontRustls, RecvMemory, server_bind},
    timer::TimeoutContainer,
    tls::MutexCertificateResolver,
};

StateMachineBuilder! {
    /// The various Stages of an HTTPS connection:
    ///
    /// - optional (ExpectProxyProtocol)
    /// - TLS handshake
    /// - HTTP or HTTP2 (via Mux)
    /// - WebSocket (passthrough), only from HTTP/1.1
    enum HttpsStateMachine impl SessionState {
        Expect(ExpectProxyProtocol<MioTcpStream>, ServerConnection),
        Handshake(TlsHandshake),
        Mux(MuxTls),
        WebSocket(Pipe<FrontRustls, HttpsListener>),
    }
}

enum AlpnProtocol {
    H2,
    Http11,
}

/// Monotonic rank of an HTTPS lifecycle stage, used only by `debug_assert!`s to
/// check that upgrades move strictly forward (Expect → Handshake → Mux →
/// WebSocket) and never re-enter an earlier stage. Gated to debug builds so it
/// does not register as dead code in release.
#[cfg(debug_assertions)]
fn https_stage_rank(marker: StateMarker) -> u8 {
    match marker {
        StateMarker::Expect => 0,
        StateMarker::Handshake => 1,
        StateMarker::Mux => 2,
        StateMarker::WebSocket => 3,
    }
}

/// Module-level prefix for log lines emitted from this file when no session
/// is in scope. Produces a bold bright-white `HTTPS` label in colored mode.
/// Used by [`HttpsProxy`] / [`HttpsListener`] callbacks (`notify`,
/// `add_cluster`, `add_*_frontend`, `accept`, `soft_stop`, `hard_stop`)
/// which own a token map keyed by listener and have no `frontend_token` of
/// their own.
macro_rules! log_module_context {
    () => {{
        let (open, reset, _, _, _) = sozu_command::logging::ansi_palette();
        format!("{open}HTTPS{reset}\t >>>", open = open, reset = reset)
    }};
}

/// Per-session prefix for log lines emitted with an [`HttpsSession`] in
/// scope. Renders the canonical `\tHTTPS\tSession(...)\t >>>` envelope from
/// the session's `frontend_token` and `peer_address`. Operators can grep-
/// correlate against the token id (and the peer address when present)
/// across log lines for the same TLS connection.
macro_rules! log_context {
    ($self:expr) => {{
        let (open, reset, grey, gray, white) = sozu_command::logging::ansi_palette();
        format!(
            "{open}HTTPS{reset}\t{grey}Session{reset}({gray}frontend{reset}={white}{frontend}{reset}, {gray}peer{reset}={white}{peer}{reset})\t >>>",
            open = open,
            reset = reset,
            grey = grey,
            gray = gray,
            white = white,
            frontend = $self.frontend_token.0,
            peer = $self.peer_address.map(|a| a.to_string()).unwrap_or_else(|| "<none>".to_string()),
        )
    }};
}

fn successful_tls_handshake_summary(sni: Option<&str>, alpn: Option<&str>) -> String {
    format!(
        "successful TLS handshake (sni_bytes={:?}, alpn_bytes={:?})",
        sni.map(str::len),
        alpn.map(str::len),
    )
}

/// The readiness events the upgraded mux frontend starts with.
///
/// WRITABLE always: the H2 server must send its SETTINGS whatever the peer
/// does next, and an upgrade from `TlsHandshake::writable` has no fresh event.
///
/// READABLE only when a read is due without a new edge:
///
/// - `handshake_event` still carries READABLE. `handshake_read`
///   (`lib/src/protocol/rustls.rs`) drops it exactly when a `recv` proved the
///   receive queue empty — EAGAIN or a short read — and any segment that
///   arrived since raised an edge that `TlsHandshake::update_readiness` put
///   back;
/// - `rustls_holds_input`: `ServerConnection::wants_read()` is false, so
///   rustls already decrypted plaintext — the HTTP/2 preface or an HTTP/1.1
///   request that shared a segment with the client `Finished` — or received
///   `close_notify`. Neither will raise an edge, and the mux read serves both
///   without a `recv`.
///
/// Anything else means the socket was drained after the last edge, and bytes
/// arriving later raise their own event (mio registers edge-triggered, see
/// `plain_socket_read` in `lib/src/socket.rs`), so an unconditional READABLE
/// only bought a `recv` that answered EAGAIN on every TLS connection.
///
/// HUP and WRITE_CLOSED survive the upgrade: their edge does not fire again,
/// and WRITE_CLOSED is what tells the mux a hang-up from a half-close. A client that
/// half-closed with its request (`TlsHandshake::ready` in
/// `lib/src/protocol/rustls.rs` reads past that HUP) is served by the mux,
/// which closes the session on the HUP once the response is complete
/// (`Mux::ready_inner`). Dropping it left that session open after its
/// response until the frontend timeout.
fn upgraded_frontend_events(handshake_event: Ready, rustls_holds_input: bool) -> Ready {
    // WRITE_CLOSED too: it is what tells a hang-up from a half-close.
    let hup = handshake_event & (Ready::HUP | Ready::WRITE_CLOSED);
    if handshake_event.is_readable() || rustls_holds_input {
        Ready::READABLE | Ready::WRITABLE | hup
    } else {
        Ready::WRITABLE | hup
    }
}

/// Render an SNI trie key as the `domain` of a [`CertificateSummary`].
///
/// Unreachable in practice: every key enters the trie as
/// `String::into_bytes()` (`tls.rs` `add_certificate`/`remove_certificate`),
/// so it is always valid UTF-8. `TrieNode`'s key type is `Vec<u8>` though, and
/// a read-only certificate listing must degrade rather than abort the worker.
///
/// The degradation is not silent: `CertificateSummary::domain` is a protobuf
/// `string`, so a non-UTF-8 name has no faithful rendering, and the U+FFFD
/// substitutions mean the name handed to the operator will NOT match a later
/// `RemoveCertificate` for that certificate. That is worth an `error!` rather
/// than a quietly mangled row. The log carries byte counts only — never the
/// key — to stay inside the redaction bound the `query_*` log tests assert.
fn certificate_summary_domain(key: &[u8]) -> String {
    match from_utf8(key) {
        Ok(domain) => domain.to_owned(),
        Err(error) => {
            error!(
                "{} certificate domain is not valid UTF-8; the reported name is lossy and will not \
                 match a later RemoveCertificate, domain_bytes={} valid_up_to={}",
                log_module_context!(),
                key.len(),
                error.valid_up_to(),
            );
            String::from_utf8_lossy(key).into_owned()
        }
    }
}

pub struct HttpsSession {
    configured_backend_timeout: Duration,
    configured_connect_timeout: Duration,
    configured_frontend_timeout: Duration,
    frontend_token: Token,
    has_been_closed: bool,
    last_event: Instant,
    listener: Rc<RefCell<HttpsListener>>,
    metrics: SessionMetrics,
    peer_address: Option<StdSocketAddr>,
    pool: Weak<RefCell<Pool>>,
    proxy: Rc<RefCell<HttpsProxy>>,
    public_address: StdSocketAddr,
    state: HttpsStateMachine,
}

impl HttpsSession {
    #[allow(clippy::too_many_arguments)]
    pub fn new(
        configured_backend_timeout: Duration,
        configured_connect_timeout: Duration,
        configured_frontend_timeout: Duration,
        configured_request_timeout: Duration,
        expect_proxy: bool,
        listener: Rc<RefCell<HttpsListener>>,
        pool: Weak<RefCell<Pool>>,
        proxy: Rc<RefCell<HttpsProxy>>,
        public_address: StdSocketAddr,
        rustls_details: ServerConnection,
        sock: MioTcpStream,
        peer: StdSocketAddr,
        token: Token,
        wait_time: Duration,
    ) -> HttpsSession {
        // Timeouts are wired from the listener config and feed `TimeoutContainer`s
        // that arm the event loop. A zero request timeout would arm a deadline that
        // fires on the very next tick, so reaching this constructor with one signals
        // a config-loading bug upstream rather than hostile input.
        debug_assert!(
            !configured_request_timeout.is_zero(),
            "HTTPS session request timeout must be non-zero (would arm an immediate deadline)"
        );
        debug_assert!(
            !configured_frontend_timeout.is_zero() && !configured_backend_timeout.is_zero(),
            "HTTPS session front/back timeouts must be non-zero"
        );

        let peer_address = if expect_proxy {
            // Will be defined later once the expect proxy header has been received and parsed
            None
        } else {
            // The address `accept(2)` returned with `sock`.
            Some(peer)
        };

        let request_id = Ulid::generate();
        let container_frontend_timeout = TimeoutContainer::new(configured_request_timeout, token);

        let state = if expect_proxy {
            trace!("{} starting in expect proxy state", log_module_context!());
            gauge_add!(names::protocol::PROXY_EXPECT, 1);
            HttpsStateMachine::Expect(
                ExpectProxyProtocol::new(container_frontend_timeout, sock, token, request_id),
                rustls_details,
            )
        } else {
            gauge_add!(names::protocol::TLS_HANDSHAKE, 1);
            HttpsStateMachine::Handshake(TlsHandshake::new(
                container_frontend_timeout,
                rustls_details,
                sock,
                token,
                request_id,
                peer_address,
            ))
        };

        // The freshly built state must reflect the entry-protocol choice exactly:
        // `expect_proxy` enters via PROXY-protocol parsing, otherwise straight into
        // the TLS handshake. No other entry state is legal, and `peer_address` is
        // unknown until the PROXY header is parsed (mirror of the `if` above).
        debug_assert_eq!(
            matches!(state, HttpsStateMachine::Expect(..)),
            expect_proxy,
            "fresh HTTPS session must start in Expect iff expect_proxy is set"
        );
        debug_assert!(
            expect_proxy || matches!(state, HttpsStateMachine::Handshake(_)),
            "non-expect-proxy HTTPS session must start in the TLS Handshake state"
        );
        debug_assert!(
            !expect_proxy || peer_address.is_none(),
            "expect-proxy peer address is only known after the PROXY header is parsed"
        );

        let metrics = SessionMetrics::new(Some(wait_time));
        HttpsSession {
            configured_backend_timeout,
            configured_connect_timeout,
            configured_frontend_timeout,
            frontend_token: token,
            has_been_closed: false,
            last_event: Instant::now(),
            listener,
            metrics,
            peer_address,
            pool,
            proxy,
            public_address,
            state,
        }
    }

    pub fn upgrade(&mut self) -> SessionIsToBeClosed {
        debug!("{} upgrade", log_context!(self));
        // `take()` swaps in a FailedUpgrade carrying the marker of the state we
        // are leaving, so the marker observed here is the *origin* of this
        // upgrade. Capture it to check the transition is forward-only below.
        // Read only by debug-only asserts → cfg-gated so release has no unused
        // binding.
        #[cfg(debug_assertions)]
        let from_marker = self.state.marker();
        let new_state = match self.state.take() {
            HttpsStateMachine::Expect(expect, ssl) => self.upgrade_expect(expect, ssl),
            HttpsStateMachine::Handshake(handshake) => self.upgrade_handshake(handshake),
            HttpsStateMachine::Mux(mux) => self.upgrade_mux(mux),
            HttpsStateMachine::WebSocket(wss) => self.upgrade_websocket(wss),
            HttpsStateMachine::FailedUpgrade(_) => {
                // Reaching this arm means a prior upgrade already returned
                // `None` and the session should have been closed. Fall back
                // to closing cleanly instead of panicking the worker.
                error!(
                    "{} upgrade called on FailedUpgrade state; closing session",
                    log_context!(self)
                );
                None
            }
        };

        match new_state {
            Some(state) => {
                // The HTTPS lifecycle is strictly forward: Expect → Handshake →
                // Mux → WebSocket. A successful upgrade must move to a strictly
                // later stage and never re-enter the one it came from (no
                // re-handshake mid-stream, no fall-back to Expect). `WebSocket`
                // is terminal: `upgrade_websocket` returns the same state, so we
                // exempt the self-loop there. The whole assert is cfg-gated (not
                // just `debug_assert!`'s runtime guard) because its argument calls
                // the debug-only `https_stage_rank`; leaving the call to compile
                // in release would be an E0425 (HARD RULE #2).
                #[cfg(debug_assertions)]
                debug_assert!(
                    https_stage_rank(state.marker()) > https_stage_rank(from_marker)
                        || matches!(from_marker, StateMarker::WebSocket),
                    "HTTPS upgrade must advance the lifecycle (from {:?} to {:?})",
                    from_marker,
                    state.marker()
                );
                debug_assert!(
                    !state.failed(),
                    "a successful HTTPS upgrade must not yield a FailedUpgrade state"
                );
                self.state = state;
                false
            }
            // The state stays FailedUpgrade, but the Session should be closed right after
            None => {
                // On a refused upgrade `take()` left a FailedUpgrade behind that
                // still remembers the origin stage, so `close()` can restore the
                // right gauge. Guard that the marker survived the failed attempt.
                debug_assert!(
                    self.state.failed(),
                    "a refused HTTPS upgrade must leave the state in FailedUpgrade"
                );
                // cfg-gated for the same E0425 reason as the success arm above.
                #[cfg(debug_assertions)]
                debug_assert!(
                    https_stage_rank(self.state.marker()) == https_stage_rank(from_marker),
                    "FailedUpgrade must retain the origin stage marker for gauge restoration"
                );
                true
            }
        }
    }

    fn upgrade_expect(
        &mut self,
        mut expect: ExpectProxyProtocol<MioTcpStream>,
        ssl: ServerConnection,
    ) -> Option<HttpsStateMachine> {
        if let Some(ref addresses) = expect.addresses
            && let (Some(public_address), Some(session_address)) =
                (addresses.destination(), addresses.source())
        {
            self.public_address = public_address;
            self.peer_address = Some(session_address);

            let ExpectProxyProtocol {
                container_frontend_timeout,
                frontend,
                frontend_readiness: readiness,
                request_id,
                ..
            } = expect;

            let mut handshake = TlsHandshake::new(
                container_frontend_timeout,
                ssl,
                frontend,
                self.frontend_token,
                request_id,
                self.peer_address,
            );
            // Transfer both interest and event from the proxy protocol state,
            // so the event loop properly monitors the socket after the transition.
            handshake.frontend_readiness = readiness;
            handshake.frontend_readiness.event.insert(Ready::READABLE);

            // The PROXY header just resolved both endpoints; the session now
            // knows its true peer, and the handshake must watch for readable
            // bytes or the TLS ClientHello will never be serviced.
            debug_assert_eq!(
                self.peer_address,
                Some(session_address),
                "expect upgrade must adopt the PROXY-advertised source as the peer address"
            );
            debug_assert!(
                handshake.frontend_readiness.event.is_readable(),
                "handshake handed off from expect must be armed for READABLE"
            );

            gauge_add!(names::protocol::PROXY_EXPECT, -1);
            gauge_add!(names::protocol::TLS_HANDSHAKE, 1);
            return Some(HttpsStateMachine::Handshake(handshake));
        }

        // currently, only happens in expect proxy protocol with AF_UNSPEC address
        if !expect.container_frontend_timeout.cancel() {
            error!(
                "{} failed to cancel request timeout on expect upgrade phase for 'expect proxy protocol with AF_UNSPEC address'",
                log_context!(self)
            );
        }

        None
    }

    fn upgrade_handshake(&mut self, handshake: TlsHandshake) -> Option<HttpsStateMachine> {
        // Capture the SNI as an owned, already-lowercased String so it outlives
        // the `handshake.session` move below. Lowercasing here once avoids
        // doing it on every route decision (RFC 9110 §4.2.3 says hostnames are
        // case-insensitive); no port is ever part of an SNI value (RFC 6066
        // §3 — `HostName` is a dns_name, no port).
        // RFC 1034 §3.1 absolute-form: `example.com.` and `example.com`
        // are the same host. rustls hands us the wire-form SNI verbatim;
        // strip a single trailing dot so a legitimate client emitting
        // absolute-form SNI does not get its
        // `host` / `:authority` rejected by `authority_matches_sni` for a
        // length mismatch. Empty / no-SNI is unaffected.
        let sni_owned: Option<String> = handshake
            .session
            .server_name()
            .map(|s| s.to_ascii_lowercase())
            .map(|mut s| {
                if s.ends_with('.') {
                    s.pop();
                }
                s
            });
        let alpn = handshake.session.alpn_protocol();
        let alpn = alpn.and_then(|alpn| from_utf8(alpn).ok());
        debug!(
            "{} {}",
            log_context!(self),
            successful_tls_handshake_summary(sni_owned.as_deref(), alpn)
        );

        // Reject clients that fail to negotiate `h2` when the listener is
        // configured as H2-only: silently falling back to HTTP/1.1 would let a
        // downgrade-capable peer bypass H2-specific protections advertised
        // for this listener (Pass 5 Medium #4 of the security audit).
        let disable_http11 = self.listener.borrow().is_http11_disabled();
        // Pair the parsed AlpnProtocol with the on-the-wire label so the
        // access log can record it as a `&'static str` without re-stringifying
        // the protocol enum on every request. Unknown ALPN values still bail
        // out below — only successful negotiations propagate to the log.
        let (alpn, alpn_label): (AlpnProtocol, Option<&'static str>) = match alpn {
            Some("http/1.1") => {
                if disable_http11 {
                    incr!(names::https::ALPN_REJECTED_HTTP11_DISABLED);
                    warn!(
                        "{} rejecting TLS connection: listener is H2-only but client negotiated http/1.1",
                        log_context!(self)
                    );
                    return None;
                }
                (AlpnProtocol::Http11, Some("http/1.1"))
            }
            Some("h2") => (AlpnProtocol::H2, Some("h2")),
            Some(other) => {
                // This branch was not metered, so any operator dashboard
                // graphing `https.alpn.rejected.*`
                // missed unknown-protocol refusals (e.g. an `h3` mistake
                // bleeding through some misconfiguration). Add a dedicated
                // counter so the SOC's "ALPN refusal" ratebar matches the
                // sum of the labelled buckets.
                incr!(names::https::ALPN_REJECTED_UNSUPPORTED);
                error!(
                    "{} unsupported ALPN protocol: alpn_bytes={}",
                    log_context!(self),
                    other.len()
                );
                return None;
            }
            // Some clients don't fill in the ALPN protocol. By default we
            // downgrade to HTTP/1.1 to preserve compatibility; on an H2-only
            // listener we instead drop the connection.
            None => {
                if disable_http11 {
                    incr!(names::https::ALPN_REJECTED_HTTP11_DISABLED);
                    warn!(
                        "{} rejecting TLS connection: listener is H2-only but client did not negotiate ALPN",
                        log_context!(self)
                    );
                    return None;
                }
                (AlpnProtocol::Http11, None)
            }
        };

        // Post-decision invariant: every refusal path above already returned, so
        // reaching here means the negotiated protocol is one Sōzu serves. An
        // H2-only listener must therefore have landed on H2 — never on the H1
        // dispatch — or the `disable_http11` guard leaked a downgrade. The label,
        // when present, must name exactly the protocol we are about to build.
        debug_assert!(
            !disable_http11 || matches!(alpn, AlpnProtocol::H2),
            "H2-only listener must not dispatch an HTTP/1.1 session past ALPN"
        );
        debug_assert!(
            match (&alpn, alpn_label) {
                (AlpnProtocol::H2, Some(l)) => l == "h2",
                (AlpnProtocol::Http11, Some(l)) => l == "http/1.1",
                // Absent label only for ALPN-less HTTP/1.1 downgrade.
                (AlpnProtocol::Http11, None) => true,
                (AlpnProtocol::H2, None) => false,
            },
            "negotiated ALPN protocol and its wire label must agree"
        );

        // Capture the negotiated TLS metadata as `&'static str` labels for the
        // access log alongside the existing metric counters. Both calls are
        // single rustls accessors — duplicating them keeps the metric path
        // unchanged and avoids mutating-after-move on `handshake.session`.
        let tls_version_label = handshake
            .session
            .protocol_version()
            .and_then(rustls_version_label);
        let tls_cipher_label = handshake
            .session
            .negotiated_cipher_suite()
            .and_then(rustls_ciphersuite_label);
        if let Some(version) = handshake.session.protocol_version() {
            incr!(rustls_version_str(version));
        };
        if let Some(cipher) = handshake.session.negotiated_cipher_suite() {
            incr!(rustls_ciphersuite_str(cipher));
        };

        gauge_add!(names::protocol::TLS_HANDSHAKE, -1);

        // Read before `handshake.session` moves into `FrontRustls` below.
        let frontend_events = upgraded_frontend_events(
            handshake.frontend_readiness.event,
            !handshake.session.wants_read(),
        );
        // No READABLE left in the handshake's event: its last `recv` proved
        // the socket empty and no data event was delivered since, so the
        // first mux read serves what rustls holds without a `recv`.
        let recv_memory =
            RecvMemory::after_handshake(!handshake.frontend_readiness.event.is_readable());

        let session_ulid = rusty_ulid::Ulid::generate();
        let front_stream = FrontRustls {
            stream: handshake.stream,
            session: handshake.session,
            peer_disconnected: false,
            peer_reset: false,
            tls_fatal: false,
            session_ulid,
            // `self.peer_address`, NOT `stream.peer_addr()`. On an expect-proxy
            // frontend `upgrade_expect` has already adopted the PROXY-advertised
            // source here, while the socket's own peer is the load balancer: the
            // raw lookup compiles, passes, and silently makes the `MUX-*` lines
            // name a different host than the `HTTPS` line for the same request
            // id. This is the same value handed to `Context::new` below, so the
            // two halves of the session agree by construction.
            configured_peer: self.peer_address,
            recv_memory,
        };
        let router = mux::Router::new(
            self.configured_backend_timeout,
            self.configured_connect_timeout,
        );
        let mut context = mux::Context::new(
            session_ulid,
            self.pool.clone(),
            self.listener.clone(),
            self.peer_address,
            self.public_address,
        );
        // Snapshot the SAN set of the certificate this handshake actually
        // served. Frozen at handshake to match browser behaviour (Firefox
        // and Chrome cache the validated cert per connection — RFC 7540
        // §9.1.1 / RFC 9113 §9.1.1) and so the H2 router can accept
        // coalesced streams whose `:authority` is covered by any SAN
        // (RFC 6125 §6.4.3 wildcards).
        //
        // # Known race window (accepted risk)
        //
        // This is a SECOND lookup, separate from rustls's `resolve()`
        // callback. Between rustls's `resolve()` (during ClientHello
        // processing) and this block (post-`Finished`), the mio loop may
        // dispatch the command-channel token — handlers there call
        // `add_certificate` / `remove_certificate`, which mutate the same
        // resolver trie. The single-threaded-worker invariant prevents
        // simultaneous mutation, but not interleaving between mio
        // iterations.
        //
        // Realistic threat model: internal misuse — a tenant operator
        // with config-IPC privilege races a `remove_certificate(A)` plus
        // `add_certificate(B covering same SNI)` inside the handshake
        // window. The snapshot below then reflects B instead of A. The
        // attacker already holds the trust boundary they would need to
        // mint a malicious cert outright (config IPC == resolver write
        // privilege), so the race grants no privilege the attacker did
        // not already have. Closing it structurally would require either
        // (a) rustls API support to recover the served cert chain
        // post-handshake (`server_cert_chain` is `pub(crate)` in rustls
        // 0.23.x) or (b) threading per-session state from `resolve()` to
        // here through a side-channel that handles out-of-order handshake
        // completion — both deferred. Keep the second lookup; document
        // the window honestly.
        //
        // Cases handled:
        //   * SNI absent → `None`; routing falls back to the legacy
        //     `authority_matches_sni` predicate (no SNI ⇒ predicate no-ops).
        //   * SNI present and the resolver returned a SAN-bearing cert →
        //     `Some(snapshot)` (lowercase + trailing-dot strip + dedup).
        //     Routing accepts `:authority` covered by the SAN set with
        //     RFC 6125 §6.4.3 wildcard handling — this is the H2
        //     connection-coalescing fix (RFC 7540 §9.1.1 / RFC 9113
        //     §9.1.1, Firefox + Chrome semantics).
        //   * SNI present but no matching cert (rustls served the default
        //     cert) → `None`. The legacy exact-match fallback applies:
        //     accept iff `:authority == SNI`, identical to the pre-fix
        //     behaviour. Returning `Some(empty)` here would block every
        //     authority — including configurations where the operator
        //     intentionally keeps a frontend reachable on a different cert
        //     (test fixtures, dev setups, misconfigured listeners). The
        //     real defence stays on the client: a browser will refuse the
        //     default cert when SNI doesn't validate against it; a
        //     deliberate insecure client choosing to ignore that is
        //     responsible for its own behaviour and is not a trust-boundary
        //     concern for the proxy.
        let tls_cert_names: Option<Arc<Vec<String>>> = match sni_owned.as_deref() {
            Some(sni) => self
                .listener
                .borrow()
                .resolver()
                .names_for_sni(sni.as_bytes())
                .and_then(|names| {
                    let mut snapshot: Vec<String> = names
                        .into_iter()
                        .map(|mut name| {
                            name.make_ascii_lowercase();
                            if name.ends_with('.') {
                                name.pop();
                            }
                            name
                        })
                        .collect();
                    snapshot.sort();
                    snapshot.dedup();
                    if snapshot.is_empty() {
                        None
                    } else {
                        Some(Arc::new(snapshot))
                    }
                }),
            None => None,
        };
        // Structural postcondition of the SAN-snapshot builder above: a cert-name
        // snapshot only exists when the client sent an SNI (the `None => None`
        // arm), and when present it is non-empty (empty collapses to `None`) and
        // sorted+deduped (so the H2 router's coalescing check sees a canonical
        // set). These hold regardless of `strict_sni_binding`; the binding policy
        // is *enforced* later at routing, but the snapshot feeding it must be
        // well-formed here.
        debug_assert!(
            tls_cert_names.is_none() || sni_owned.is_some(),
            "cert-name snapshot must not exist without an SNI to key it"
        );
        debug_assert!(
            tls_cert_names
                .as_ref()
                .is_none_or(|names| { !names.is_empty() && names.windows(2).all(|w| w[0] < w[1]) }),
            "cert-name snapshot must be non-empty and strictly sorted (sorted + deduped)"
        );

        // Bind the TLS SNI to this session so the routing layer can reject any
        // H2 stream whose `:authority` crosses the TLS trust boundary (see
        // `route_from_request`).
        context.tls_server_name = sni_owned;
        context.tls_cert_names = tls_cert_names;
        // Stamp the connection-scoped TLS metadata so every per-stream
        // HttpContext created by `Context::create_stream` inherits it for
        // the access log without re-querying rustls.
        context.tls_version = tls_version_label;
        context.tls_cipher = tls_cipher_label;
        context.tls_alpn = alpn_label;
        let mut frontend = match alpn {
            AlpnProtocol::Http11 => {
                incr!(names::http::ALPN_HTTP11);
                context.create_stream(handshake.request_id, 1 << 16)?;
                mux::Connection::new_h1_server(
                    session_ulid,
                    front_stream,
                    handshake.container_frontend_timeout.duration(),
                )
            }
            AlpnProtocol::H2 => {
                incr!(names::http::ALPN_H2);
                let flood_config = self.listener.borrow().get_h2_flood_config();
                let connection_config = self.listener.borrow().get_h2_connection_config();
                let stream_idle_timeout = self.listener.borrow().get_h2_stream_idle_timeout();
                let graceful_shutdown_deadline =
                    self.listener.borrow().get_h2_graceful_shutdown_deadline();
                mux::Connection::new_h2_server(
                    session_ulid,
                    front_stream,
                    &mut *context.buffers,
                    handshake.container_frontend_timeout.duration(),
                    flood_config,
                    connection_config,
                    stream_idle_timeout,
                    graceful_shutdown_deadline,
                )?
            }
        };
        // Arm the upgraded connection. With TLS 1.3 + NewSessionTicket, the
        // upgrade may happen from writable() where READABLE is no longer in the
        // event (consumed by the prior readable() call). The HTTP/2 preface may
        // already be in rustls's plaintext buffer (not on the TCP socket), so no
        // new READABLE event from epoll will arrive: `upgraded_frontend_events`
        // arms READABLE for it, and for an edge the handshake has not read yet,
        // but not for a socket the handshake proved empty (#1609). Without
        // WRITABLE in the event, the H2 state machine cannot transition from
        // reading the preface to writing SETTINGS, causing a deadlock with
        // clients (like hyper) that wait for the server's SETTINGS before
        // proceeding.
        frontend.readiness_mut().event.insert(frontend_events);

        // Post-handoff: the mux frontend MUST be armed for WRITABLE, and for
        // READABLE whenever a read is due without a new edge, or the H2
        // preface→SETTINGS exchange deadlocks (see the comment above). This is
        // the structural guarantee the insert just made — assert it survived.
        debug_assert!(
            frontend.readiness_mut().event.is_writable()
                && (!frontend_events.is_readable() || frontend.readiness_mut().event.is_readable()),
            "post-handshake mux frontend must be armed for WRITABLE, and READABLE when due"
        );
        // The two crate halves of the H2/H1 session reference streams by a shared
        // ulid; the handshake-derived ulid must thread through both the connection
        // and its context unchanged, otherwise per-stream lookups cross sessions.
        debug_assert_eq!(
            context.session_ulid, session_ulid,
            "mux context and connection must share the handshake-derived session ulid"
        );

        gauge_add!(names::protocol::HTTPS, 1);
        Some(HttpsStateMachine::Mux(Mux {
            configured_frontend_timeout: self.configured_frontend_timeout,
            frontend_token: self.frontend_token,
            frontend,
            context,
            router,
            session_ulid,
            // Carry the already-armed handshake entry into the adapter rather
            // than dropping it and arming a fresh one: the session's request
            // timeout started when the socket was accepted.
            timeouts: mux::MuxTimeouts::new(handshake.container_frontend_timeout),
            backend_registry: mux::BackendRegistry::default(),
            // Read once, at the upgrade: the proxy is not borrowed while a
            // session runs, and `HttpsProxy::backends` is never reassigned,
            // so this is the map the session would have reached on every dial.
            backends: Rc::clone(&self.proxy.borrow().backends),
        }))
    }

    fn upgrade_mux(&self, mut mux: MuxTls) -> Option<HttpsStateMachine> {
        debug!("{} mux switching to wss", log_context!(self));
        let Some(stream) = mux.context.streams.pop() else {
            error!(
                "{} upgrade_mux: no stream attached to the TLS mux session, closing",
                log_context!(self)
            );
            return None;
        };
        // http.active_requests was already decremented by generate_access_log()
        // in h1.rs before MuxResult::Upgrade was returned to us.

        // The cores no longer own a wheel handle; the `Mux` adapter does. Move
        // the frontend's out of the adapter before dismantling the
        // connection, so the WebSocket `Pipe` inherits the same live entry it
        // used to inherit from `ConnectionH1`.
        let mut container_frontend_timeout = mux.timeouts.frontend;
        let (frontend_readiness, frontend_socket) = match mux.frontend {
            mux::Connection::H1(mux::ConnectionH1 {
                readiness, socket, ..
            }) => (readiness, socket),
            mux::Connection::H2(_) => {
                error!(
                    "{} only h1<->h1 connections can upgrade to websocket",
                    log_context!(self)
                );
                return None;
            }
        };

        let mux::StreamState::Linked(back_token) = stream.state else {
            error!(
                "{} upgrading stream should be linked to a backend",
                log_context!(self)
            );
            return None;
        };
        let Some(backend) = mux.router.backends.remove(&back_token) else {
            error!(
                "{} upgrade_mux: backend for token {:?} is missing (already disconnected?), closing",
                log_context!(self),
                back_token
            );
            return None;
        };
        let mut container_backend_timeout = mux
            .timeouts
            .backends
            .remove(&back_token)
            .unwrap_or_else(|| TimeoutContainer::new_empty(mux.router.configured_backend_timeout));
        let (cluster_id, backend_id, backend_readiness, backend_socket) = match backend {
            mux::Connection::H1(mux::ConnectionH1 {
                position: mux::Position::Client(cluster_id, backend, mux::BackendStatus::Connected),
                readiness,
                socket,
                ..
            }) => (cluster_id, backend, readiness, socket),
            mux::Connection::H1(_) => {
                error!(
                    "{} the backend disconnected just after upgrade, abort",
                    log_context!(self)
                );
                return None;
            }
            mux::Connection::H2(_) => {
                error!(
                    "{} only h1<->h1 connections can upgrade to websocket",
                    log_context!(self)
                );
                return None;
            }
        };

        // The mux core carries an opaque `BackendId` (#1340, Q12); the
        // WebSocket `Pipe` that takes this backend over still owns the
        // registry handle, so resolve it here, on the embedder's side of that
        // perimeter, through the one accessor there is.
        let Some(backend) = mux.backend_registry.handle(&backend_id).cloned() else {
            error!(
                "{} upgrade_mux: backend {:?} names a slot this session never minted, closing",
                log_context!(self),
                backend_id.backend_id
            );
            return None;
        };
        let metric_incarnation = backend_id.metric_incarnation();
        let backend_id = backend_id.backend_id.to_string();

        let ws_context = stream.context.websocket_context();

        container_frontend_timeout.reset();
        container_backend_timeout.reset();

        // Unwrap the `SessionTcpStream` that the mux put around every backend
        // TCP socket — `Pipe::backend_socket` is typed `Option<TcpStream>`.
        let backend_socket = backend_socket.stream;
        let mut pipe = Pipe::new(
            stream.back.storage.buffer,
            Some(backend_id),
            Some(backend_socket),
            Some(backend),
            Some(container_backend_timeout),
            Some(container_frontend_timeout),
            Some(cluster_id),
            stream.front.storage.buffer,
            self.frontend_token,
            frontend_socket,
            self.listener.clone(),
            Protocol::HTTPS,
            stream.context.session_id,
            stream.context.id,
            stream.context.session_address,
            ws_context,
        );
        pipe.set_cluster_metrics_incarnation(metric_incarnation);

        pipe.restore_readiness_events(frontend_readiness.event, backend_readiness.event);
        pipe.set_back_token(back_token);
        // The WSS pipe is a frontend↔backend bridge: it only exists because the
        // upgrading stream was `Linked(back_token)` to a *connected* backend (the
        // guard arms above already rejected `!Connected` and missing backends).
        // So the back token must be set, and set to exactly the token we routed.
        debug_assert!(
            pipe.back_token().contains(&back_token),
            "WSS pipe back token must be the connected backend token carried from the mux"
        );
        // Carry the connection-scoped TLS metadata captured at handshake time
        // into the post-upgrade WSS pipe so its access log records the same
        // version/cipher/sni/alpn the H1 request log already emitted. `clone`
        // on the SNI is the only heap touch — the other three are
        // `&'static str` borrows into the rustls label tables.
        pipe.set_tls_metadata(
            stream.context.tls_version,
            stream.context.tls_cipher,
            stream.context.tls_server_name.clone(),
            stream.context.tls_alpn,
        );

        // Gauge accounting for the Mux→WebSocket transition is a balanced
        // hand-off: exactly one HTTPS gauge leaves and one WSS gauge arrives, so
        // the live-session total is conserved. The readiness events captured from
        // the mux frontend/backend must survive the transfer into the pipe — a
        // lost event would silently park the bridge with no epoll wake-up.
        debug_assert_eq!(
            pipe.frontend_readiness.event, frontend_readiness.event,
            "WSS pipe must inherit the mux frontend readiness event verbatim"
        );
        debug_assert_eq!(
            pipe.backend_readiness.event, backend_readiness.event,
            "WSS pipe must inherit the mux backend readiness event verbatim"
        );

        // http.active_requests was already decremented by generate_access_log()
        // in h1.rs when the 101 response was written (before MuxResult::Upgrade).
        gauge_add!(names::protocol::HTTPS, -1);
        gauge_add!(names::protocol::WSS, 1);
        gauge_add!(names::websocket::ACTIVE_REQUESTS, 1);
        Some(HttpsStateMachine::WebSocket(pipe))
    }

    fn upgrade_websocket(
        &self,
        wss: Pipe<FrontRustls, HttpsListener>,
    ) -> Option<HttpsStateMachine> {
        // what do we do here?
        error!(
            "{} upgrade called on WSS, this should not happen",
            log_context!(self)
        );
        Some(HttpsStateMachine::WebSocket(wss))
    }

    /// Full cross-field invariant sweep for the session state machine, run as a
    /// run-to-completion postcondition at the end of `ready()` (the public
    /// mutating entry point). Encodes only relationships that must hold for any
    /// live HTTPS session regardless of network input; a violation here is a
    /// Sōzu logic bug, never a property of hostile traffic.
    #[cfg(debug_assertions)]
    fn check_invariants(&self) {
        // Timeouts are immutable for the session's lifetime and were validated as
        // non-zero at construction; they must never drift to zero (which would
        // arm an immediate-firing deadline on the next state hand-off).
        debug_assert!(
            !self.configured_frontend_timeout.is_zero()
                && !self.configured_backend_timeout.is_zero()
                && !self.configured_connect_timeout.is_zero(),
            "HTTPS session timeouts must stay non-zero for the session lifetime"
        );
        // The marker is total over the four live stages plus FailedUpgrade; a
        // FailedUpgrade session is awaiting close and must report `failed()`,
        // while any of the four live stages must not. This is the structural
        // bridge the gauge-restore logic in `close()` relies on.
        if self.state.failed() {
            debug_assert!(
                matches!(
                    self.state.marker(),
                    StateMarker::Expect
                        | StateMarker::Handshake
                        | StateMarker::Mux
                        | StateMarker::WebSocket
                ),
                "FailedUpgrade must retain a valid origin-stage marker"
            );
        } else {
            debug_assert!(
                !self.state.failed(),
                "a non-failed session must not also report FailedUpgrade"
            );
        }
        // Before the PROXY header resolves, the Expect stage has no peer address;
        // once any later stage is reached the address is either the real peer
        // (direct TLS) or the PROXY-advertised source. We only assert the Expect
        // direction, since direct-TLS `peer_addr()` may legitimately fail and
        // leave `None` at handshake time.
        debug_assert!(
            !matches!(self.state.marker(), StateMarker::Expect)
                || self.peer_address.is_none()
                || self.state.failed(),
            "a live Expect-stage session has no resolved peer address yet"
        );
    }
}

impl ProxySession for HttpsSession {
    fn close(&mut self) {
        if self.has_been_closed {
            return;
        }
        // Reaching past the idempotency guard means this is the *first* close.
        // Every exit below sets `has_been_closed = true`, so a clear flag here is
        // a real precondition (the gauge restore that follows must run exactly
        // once or the per-protocol gauge underflows / over-counts).
        debug_assert!(
            !self.has_been_closed,
            "close() body must run only on a not-yet-closed session"
        );

        trace!("{} closing HTTPS session", log_context!(self));
        self.metrics.service_stop();

        // Restore gauges
        match self.state.marker() {
            StateMarker::Expect => gauge_add!(names::protocol::PROXY_EXPECT, -1),
            StateMarker::Handshake => gauge_add!(names::protocol::TLS_HANDSHAKE, -1),
            StateMarker::Mux => gauge_add!(names::protocol::HTTPS, -1),
            StateMarker::WebSocket => {
                gauge_add!(names::protocol::WSS, -1);
                gauge_add!(names::websocket::ACTIVE_REQUESTS, -1);
            }
        }

        if self.state.failed() {
            match self.state.marker() {
                StateMarker::Expect => incr!(names::https::UPGRADE_EXPECT_FAILED),
                StateMarker::Handshake => incr!(names::https::UPGRADE_HANDSHAKE_FAILED),
                StateMarker::Mux => incr!(names::https::UPGRADE_MUX_FAILED),
                StateMarker::WebSocket => incr!(names::https::UPGRADE_WSS_FAILED),
            }
            // FailedUpgrade means the socket was consumed by a failed upgrade
            // attempt, so we can only close the state (no-op) and remove the
            // session — cancel_timeouts / front_socket are unreachable.
            self.state.close(self.proxy.clone(), &mut self.metrics);
            self.proxy.borrow().remove_session(self.frontend_token);
            self.has_been_closed = true;
            return;
        }

        self.state.cancel_timeouts();
        // defer backend closing to the state
        // in case of https it should also send a close notify on the client before the socket is closed below
        self.state.close(self.proxy.clone(), &mut self.metrics);

        // Shut down the write side only. shutdown(Both) includes SHUT_RD which
        // discards unread data in the receive buffer (e.g. client's GOAWAY, ACKs).
        // On Linux, close() after SHUT_RD with discarded receive data sends TCP RST
        // instead of FIN, destroying any data still in the send buffer — including
        // TLS records that the drain loop just flushed. Using SHUT_WR only sends
        // FIN after all send buffer data is delivered, preserving the response.
        // Skipped once the client has closed its side: the close that follows
        // sends the same FIN or RST on its own (`mux::shutdown_write`). Over
        // TLS that includes a client whose EOF or `close_notify` a read has
        // already met (`FrontRustls::peer_disconnected`), which no epoll
        // event reports when the close follows in the same pass.
        let peer_closed = match &self.state {
            HttpsStateMachine::Mux(mux) => {
                mux.frontend_peer_closed()
                    || match &mux.frontend {
                        mux::Connection::H1(connection) => connection.socket.peer_disconnected,
                        mux::Connection::H2(connection) => connection.socket.peer_disconnected,
                    }
            }
            _ => false,
        };
        let front_socket = self.state.front_socket();
        if let Err(e) = mux::shutdown_write(front_socket, peer_closed) {
            // error 107 NotConnected can happen when was never fully connected, or was already disconnected due to error
            if e.kind() != ErrorKind::NotConnected {
                error!(
                    "{} error shutting down front socket({:?}): {:?}",
                    log_context!(self),
                    front_socket,
                    e
                );
            }
        }

        // No `EPOLL_CTL_DEL` for the front socket: its only descriptor closes
        // when this session drops, which `shut_down_sessions_by_frontend_tokens`
        // (`lib/src/server.rs`) does before the event loop's next `epoll_wait`,
        // and Linux removes a file from every epoll set on its last close.
        // That holds because nothing duplicates a session socket: no `dup` or
        // `try_clone`, no fork from a worker, and SCM_RIGHTS only carries
        // listeners. The explicit deregister was one syscall per connection
        // that bought nothing; see §11 of `doc/lifetime_of_a_session.md`.
        let proxy = self.proxy.borrow();
        proxy.remove_session(self.frontend_token);

        self.has_been_closed = true;
        // Postcondition: a session that completed `close()` is sealed — any later
        // `close()` short-circuits on the guard above, keeping the gauge restore
        // single-shot.
        debug_assert!(
            self.has_been_closed,
            "close() must leave the session marked closed"
        );
    }

    fn timeout(&mut self, token: Token) -> SessionIsToBeClosed {
        let session_result = self.state.timeout(token, &mut self.metrics);
        if session_result == StateResult::CloseSession {
            debug!(
                "{} HTTPS timeout requested close: token={:?}, marker={:?}",
                log_context!(self),
                token,
                self.state.marker()
            );
        }
        session_result == StateResult::CloseSession
    }

    fn needs_ready_pass(&self) -> bool {
        matches!(&self.state, HttpsStateMachine::Mux(mux) if mux.has_pending_backend_failure())
    }

    fn protocol(&self) -> Protocol {
        Protocol::HTTPS
    }

    fn update_readiness(&mut self, token: Token, events: Ready) {
        trace!(
            "{} token {:?} got event {}",
            log_context!(self),
            token,
            super::ready_to_string(events)
        );
        self.last_event = Instant::now();
        self.metrics.wait_start();
        if token == self.frontend_token {
            // Whatever a `recv` proved about the frontend's receive queue,
            // bytes may have arrived since: `RecvMemory` (`lib/src/socket.rs`).
            match &mut self.state {
                HttpsStateMachine::Mux(mux) => mux
                    .frontend
                    .socket_handler_mut()
                    .readiness_delivered(events),
                HttpsStateMachine::WebSocket(pipe) => {
                    pipe.front_socket_handler_mut().readiness_delivered(events)
                }
                // No `FrontRustls` yet, or none any more.
                HttpsStateMachine::Expect(..)
                | HttpsStateMachine::Handshake(_)
                | HttpsStateMachine::FailedUpgrade(_) => {}
            }
        }
        self.state.update_readiness(token, events);
    }

    fn ready(&mut self, session: Rc<RefCell<dyn ProxySession>>) -> SessionIsToBeClosed {
        self.metrics.service_start();

        let session_result =
            self.state
                .ready(session.clone(), self.proxy.clone(), &mut self.metrics);

        let to_be_closed = match session_result {
            SessionResult::Close => true,
            SessionResult::Continue => false,
            SessionResult::Upgrade => match self.upgrade() {
                false => self.ready(session),
                true => true,
            },
        };
        if to_be_closed {
            debug!(
                "{} HTTPS ready requested close: marker={:?}",
                log_context!(self),
                self.state.marker()
            );
        }

        // Run-to-completion postcondition: whatever state `ready()` (and any
        // nested upgrade) left the session in must satisfy the full cross-field
        // invariant set before we yield back to the event loop.
        #[cfg(debug_assertions)]
        self.check_invariants();

        self.metrics.service_stop();
        to_be_closed
    }

    fn shutting_down(&mut self) -> SessionIsToBeClosed {
        self.state.shutting_down()
    }

    fn last_event(&self) -> Instant {
        self.last_event
    }

    fn print_session(&self) {
        self.state.print_state("HTTPS");
        error!("{} Metrics: {:?}", log_context!(self), self.metrics);
    }

    fn frontend_token(&self) -> Token {
        self.frontend_token
    }
}

pub type HostName = String;
pub type PathBegin = String;

pub struct HttpsListener {
    active: bool,
    address: StdSocketAddr,
    answers: Rc<RefCell<HttpAnswers>>,
    config: HttpsListenerConfig,
    fronts: Router,
    listener: Option<MioTcpListener>,
    /// A socket this listener holds but has NOT registered.
    ///
    /// `activate()` parks an inherited socket here when `Registry::register`
    /// fails, instead of letting the `?` drop and close a descriptor
    /// `Listeners::get_*` has already removed from the SCM table (sozu#1342).
    /// The next activation reuses it rather than binding a second one.
    ///
    /// Deliberately NOT `listener`: every other consumer reads that field's `Some` as
    /// "registered and live" — `soft_stop` and `hard_stop` deregister it and
    /// report the failure, `give_back_listener` hands it back as an activated
    /// socket, `accept` accepts on it. A parked socket is none of those things,
    /// and putting it there made a failed registration answer `ENOENT` from
    /// `deregister` and fail the whole soft stop.
    parked_listener: Option<MioTcpListener>,
    /// Set by `activate()`, cleared by the first `accept()` that answers
    /// `WouldBlock`: while set, `accept()` sets `TCP_NODELAY` on each socket
    /// it returns, because a connection queued before `activate()` set the
    /// flag on the listener did not inherit it. See the field of the same
    /// name on `HttpListener` (`lib/src/http.rs`).
    nodelay_backlog: bool,
    resolver: Arc<MutexCertificateResolver>,
    rustls_details: Arc<RustlsServerConfig>,
    tags: BTreeMap<String, CachedTags>,
    token: Token,
}

impl ListenerHandler for HttpsListener {
    fn get_addr(&self) -> &StdSocketAddr {
        &self.address
    }

    fn get_tags(&self, key: &str) -> Option<&CachedTags> {
        self.tags.get(key)
    }

    fn set_tags(&mut self, key: String, tags: Option<BTreeMap<String, String>>) {
        match tags {
            Some(tags) => self.tags.insert(key, CachedTags::new(tags)),
            None => self.tags.remove(&key),
        };
    }

    fn protocol(&self) -> Protocol {
        Protocol::HTTPS
    }

    fn public_address(&self) -> StdSocketAddr {
        self.config
            .public_address
            .map(|addr| addr.into())
            .unwrap_or(self.address)
    }
}

impl L7ListenerHandler for HttpsListener {
    fn get_sticky_name(&self) -> &str {
        &self.config.sticky_name
    }

    fn get_sozu_id_header(&self) -> &str {
        self.config
            .sozu_id_header
            .as_deref()
            .filter(|s| !s.is_empty())
            .unwrap_or("Sozu-Id")
    }

    fn get_connect_timeout(&self) -> u32 {
        self.config.connect_timeout
    }

    fn frontend_from_request(
        &self,
        host: &str,
        uri: &str,
        method: &Method,
    ) -> Result<RouteResult, FrontendFromRequestError> {
        let start = Instant::now();
        let (remaining_input, (hostname, _)) = match hostname_and_port(host.as_bytes()) {
            Ok(tuple) => tuple,
            Err(parse_error) => {
                // parse_error contains a slice of given_host, which should NOT escape this scope
                return Err(FrontendFromRequestError::HostParse {
                    host: host.to_owned(),
                    error: parse_error.to_string(),
                });
            }
        };

        if remaining_input != &b""[..] {
            return Err(FrontendFromRequestError::InvalidCharsAfterHost(
                host.to_owned(),
            ));
        }

        // it is alright to call from_utf8_unchecked,
        // we already verified that there are only ascii
        // chars in there
        // SAFETY: `hostname` was just produced by `hostname_and_port`
        // (`lib/src/protocol/kawa_h1/parser.rs`), which only accepts
        // bytes matching `is_hostname_char` (alphanumeric, `-`, `.`, plus
        // `_` under the tolerant-http1-parser feature). All accepted
        // bytes are ASCII (≤ 0x7F), so the slice is valid single-byte UTF-8.
        let host = unsafe { from_utf8_unchecked(hostname) };

        let route = self.fronts.lookup(host, uri, method).map_err(|e| {
            incr!(names::http::FAILED_BACKEND_MATCHING);
            FrontendFromRequestError::NoClusterFound(e)
        })?;

        let now = Instant::now();

        if let Some(cluster) = route.cluster_id.as_deref() {
            time!(
                names::event_loop::FRONTEND_MATCHING_TIME,
                cluster,
                (now - start).as_millis()
            );
        }

        Ok(route)
    }

    fn get_answers(&self) -> &Rc<RefCell<HttpAnswers>> {
        &self.answers
    }

    fn get_h2_flood_config(&self) -> crate::protocol::mux::H2FloodConfig {
        // `H2FloodConfig`'s fields are private and `from_optional` applies the
        // `.max(1)` clamp `new` carries (sozu-proxy/sozu#1418). This used to be
        // a raw struct literal, which skipped that clamp on the only path that
        // carries operator-set thresholds: config load rejects an out-of-range
        // knob (`ConfigError::H2ThresholdBelowMinimum`), and the clamp is the
        // structural backstop for a raw protobuf `AddHttpsListener` or a
        // state file saved before that gate existed.
        crate::protocol::mux::H2FloodConfig::from_optional(
            self.config.h2_max_rst_stream_per_window,
            self.config.h2_max_ping_per_window,
            self.config.h2_max_settings_per_window,
            self.config.h2_max_empty_data_per_window,
            self.config.h2_max_window_update_stream0_per_window,
            self.config.h2_max_continuation_frames,
            self.config.h2_max_glitch_count,
            self.config.h2_max_rst_stream_lifetime,
            self.config.h2_max_rst_stream_abusive_lifetime,
            self.config.h2_max_rst_stream_emitted_lifetime,
            self.config.h2_max_header_list_size,
            self.config.h2_max_header_table_size,
            self.config.h2_max_header_fields,
            self.config.h2_stream_refusal_percent,
        )
    }

    fn get_h2_connection_config(&self) -> crate::protocol::mux::H2ConnectionConfig {
        crate::protocol::mux::H2ConnectionConfig::from_optional(
            self.config.h2_initial_connection_window,
            self.config.h2_max_concurrent_streams,
            self.config.h2_stream_shrink_ratio,
        )
    }

    fn get_strict_sni_binding(&self) -> bool {
        // SNI↔:authority binding is enforced by default (closes
        // CWE-346 / CWE-444); this listener knob preserves that
        // behavior by default and lets operators opt out when cross-SNI
        // routing is intentional.
        //
        // Note: `strict_sni_binding = false` theoretically allows an
        // attacker to present many distinct SNIs on the same TCP
        // connection. rustls 0.23 **bans TLS renegotiation outright** (see
        // `rustls::server::ClientHello` which is consumed during the initial
        // handshake only), so a single TCP connection gets exactly one SNI
        // for its lifetime — the cross-SNI-flood vector is not reachable in
        // practice. Kept documented here so a future rustls upgrade that
        // reintroduces renegotiation (vanishingly unlikely) surfaces the
        // assumption during review.
        self.config.strict_sni_binding.unwrap_or(true)
    }

    fn get_elide_x_real_ip(&self) -> bool {
        self.config.elide_x_real_ip.unwrap_or(false)
    }

    fn get_send_x_real_ip(&self) -> bool {
        self.config.send_x_real_ip.unwrap_or(false)
    }

    fn get_forwarded_headers(&self) -> ForwardedHeaders {
        // An unknown wire value reads as the default, like prost's own
        // getter; `update_config` and the main-process state refuse one.
        self.config.forwarded_headers()
    }

    fn get_h2_stream_idle_timeout(&self) -> std::time::Duration {
        // Inherit `back_timeout` when the knob is unset so listeners tuned for
        // long-running backends do not cancel streams at the 30 s security
        // floor. The `max(30, …)` keeps the baseline slow-multiplex mitigation
        // when `back_timeout` is shorter than 30 s. Explicit values (including
        // ones below 30 s) win — operators under a slow-multiplex attack can
        // lower the per-stream deadline to cap buffer pinning.
        let seconds = self
            .config
            .h2_stream_idle_timeout_seconds
            .map(|s| u64::from(s.max(1)))
            .unwrap_or_else(|| u64::from(self.config.back_timeout).max(30));
        std::time::Duration::from_secs(seconds)
    }

    fn get_h2_graceful_shutdown_deadline(&self) -> Option<std::time::Duration> {
        match self.config.h2_graceful_shutdown_deadline_seconds {
            None => Some(std::time::Duration::from_secs(5)),
            Some(0) => None,
            Some(s) => Some(std::time::Duration::from_secs(u64::from(s))),
        }
    }
}

impl HttpsListener {
    /// This listener's identity: its address, plus the network interface its
    /// socket is bound to when it has one.
    pub fn key(&self) -> ListenerKey {
        ListenerKey::new(self.address, self.config.interface.as_deref())
    }

    /// Whether this listener is the one `key` names.
    pub fn is(&self, key: &ListenerKey) -> bool {
        key.matches(&self.address, self.config.interface.as_deref())
    }

    /// Whether this listener rejects clients that do not negotiate `h2`
    /// via TLS ALPN (including those that omit ALPN). Reads the
    /// `disable_http11` knob; defaults to `false` to preserve the
    /// historical behavior where a missing ALPN silently downgrades
    /// to HTTP/1.1.
    pub fn is_http11_disabled(&self) -> bool {
        self.config.disable_http11.unwrap_or(false)
    }

    /// Borrow the listener's certificate resolver. Used by the TLS handshake
    /// path to snapshot the SAN set of the certificate Sōzu serves for a
    /// given SNI, so the H2 router can accept connection coalescing
    /// (RFC 7540 §9.1.1 / RFC 9113 §9.1.1) on every authority covered by
    /// that cert (RFC 6125 §6.4.3 wildcard handling).
    pub fn resolver(&self) -> &Arc<MutexCertificateResolver> {
        &self.resolver
    }

    pub fn try_new(
        config: HttpsListenerConfig,
        token: Token,
    ) -> Result<HttpsListener, ListenerError> {
        // Defense in depth, as `update_config`: the main-process state
        // refuses an unknown mode, a raw protobuf client may not.
        if let Some(v) = config.forwarded_headers {
            validate_forwarded_headers(v)?;
        }
        let resolver = Arc::new(MutexCertificateResolver::default());

        let server_config = Arc::new(Self::create_rustls_context(&config, resolver.to_owned())?);

        let answers = Self::build_answers(&config)?;

        Ok(HttpsListener {
            listener: None,
            parked_listener: None,
            nodelay_backlog: false,
            address: config.address.into(),
            resolver,
            rustls_details: server_config,
            active: false,
            fronts: Router::new(),
            answers: Rc::new(RefCell::new(answers)),
            config,
            token,
            tags: BTreeMap::new(),
        })
    }

    /// Build the listener's HTTP answer templates from its config, reconciling
    /// the legacy `http_answers` per-status fields with the new `answers`
    /// template map (the new map wins on collision; legacy fields fill any
    /// status not yet migrated). Shared by [`Self::try_new`] and
    /// [`Self::validate_config`] so the master-side pre-commit check cannot
    /// drift from worker construction.
    fn build_answers(config: &HttpsListenerConfig) -> Result<HttpAnswers, ListenerError> {
        let mut answers_map = config.answers.clone();
        if let Some(ref legacy) = config.http_answers {
            crate::protocol::http::answers::merge_legacy_into_map(&mut answers_map, legacy);
        }
        HttpAnswers::new(&answers_map)
            .map_err(|(name, error)| ListenerError::TemplateParse(name, error))
    }

    /// Validate that a worker can build this HTTPS listener configuration — the
    /// rustls context and the answer templates — WITHOUT constructing the full
    /// listener or binding a socket. Runs the exact fallible steps of
    /// [`Self::try_new`] (via the shared [`Self::create_rustls_context`] /
    /// `Self::build_answers` helpers), so master-side validation is faithful
    /// to what the worker will do.
    ///
    /// The main process calls this before committing an `AddHttpsListener` to
    /// its `ConfigState` and fanning it out, so an invalid listener never
    /// reserves its address and blocks a corrected reload (sozu#1301).
    pub fn validate_config(config: &HttpsListenerConfig) -> Result<(), ListenerError> {
        // Buildability only; the H2 knob floors are enforced beside their
        // audience in `bin/src/command/requests.rs::validate_h2_knob_floors`
        // (sozu#1418), because a worker CAN build an out-of-range listener —
        // `H2FloodConfig::from_optional` clamps it.
        //
        // An empty resolver matches `try_new`: the default certificate is added
        // later via `AddCertificate`, so only the config-level TLS parameters
        // (versions, ciphers, groups, ALPN) and the answer templates are
        // exercised here.
        Self::create_rustls_context(config, Arc::new(MutexCertificateResolver::default()))?;
        Self::build_answers(config)?;
        Ok(())
    }

    pub fn activate(
        &mut self,
        registry: &Registry,
        tcp_listener: Option<MioTcpListener>,
    ) -> Result<Token, ListenerError> {
        if self.active {
            return Ok(self.token);
        }
        let address: StdSocketAddr = self.config.address.into();

        // Reuse a socket a previous attempt parked here after a failed
        // registration, rather than binding a second one. Taking it
        // unconditionally is what keeps the two from coexisting: if the caller
        // ALSO handed one over, the parked socket is disposed of deliberately
        // below instead of being silently overwritten.
        let parked = self.parked_listener.take();
        let mut listener = match (tcp_listener, parked) {
            (Some(inherited), Some(parked)) => {
                // Not reachable while `Listeners::get_*` removes the entry it
                // hands over and `scm_listeners` is written once: a parked
                // socket means this address's entry was already consumed, so
                // the caller cannot have another. Neither of those is enforced
                // here, so dispose of the loser explicitly and loudly rather
                // than letting an assignment close it — that silent close is
                // sozu#1342 itself.
                warn!(
                    "{} closing the socket parked on the HTTPS listener for {}: an \
                     inherited socket arrived for the same address and is the one being \
                     activated",
                    log_module_context!(),
                    address
                );
                drop(parked);
                inherited
            }
            (Some(inherited), None) => inherited,
            (None, Some(parked)) => parked,
            (None, None) => server_bind(address, self.config.interface.as_deref()).map_err(
                |server_bind_error| ListenerError::Activation {
                    address,
                    error: server_bind_error.to_string(),
                },
            )?,
        };

        // Once per listener, on whichever socket won above — freshly bound,
        // inherited over SCM_RIGHTS, or parked. Every socket accepted from now
        // on inherits it; see `nodelay_backlog` for the ones already queued.
        if let Err(e) = SockRef::from(&listener).set_tcp_nodelay(true) {
            error!(
                "{} error setting nodelay on listen socket({:?}): {:?}",
                log_module_context!(),
                listener,
                e
            );
        }

        let registration = registry
            .register(&mut listener, self.token, Interest::READABLE)
            .map_err(ListenerError::SocketRegistration);
        if let Err(error) = registration {
            // Park the socket instead of letting the `?` drop it. `register`
            // is fallible (EEXIST for a descriptor still registered because
            // `notify_deactivate_listener` only logs a failed deregister,
            // EBADF, ENOMEM), and a socket still held in a local is dropped —
            // and closed — on the way out. For an SCM-inherited socket that is
            // the sozu#1342 close in a second place: `Listeners::get_*` has
            // already removed the entry, so nothing else owns the descriptor.
            // It goes to `parked_listener`, never to `listener`, because every other
            // consumer of that field reads `Some` as "registered and live".
            self.parked_listener = Some(listener);
            return Err(error);
        }

        self.listener = Some(listener);
        self.nodelay_backlog = true;
        self.active = true;
        // Post: an activated listener owns a bound socket and is flagged active,
        // so a later `activate()` short-circuits on the `self.active` guard and
        // `give_back_listener*` find a socket to hand back. The two must move in
        // lockstep — an active listener with no socket would silently accept
        // nothing.
        debug_assert!(
            self.active && self.listener.is_some(),
            "an activated HTTPS listener must hold a bound socket and be flagged active"
        );
        Ok(self.token)
    }

    pub fn create_rustls_context(
        config: &HttpsListenerConfig,
        resolver: Arc<MutexCertificateResolver>,
    ) -> Result<RustlsServerConfig, ListenerError> {
        let cipher_names = if config.cipher_list.is_empty() {
            DEFAULT_CIPHER_LIST.to_vec()
        } else {
            config
                .cipher_list
                .iter()
                .map(|s| s.as_str())
                .collect::<Vec<_>>()
        };

        let ciphers = cipher_names
            .into_iter()
            .filter_map(|cipher| {
                cipher_suite_by_name(cipher).or_else(|| {
                    error!(
                        "{} unknown or unsupported cipher: {:?}",
                        log_module_context!(),
                        cipher
                    );
                    None
                })
            })
            .collect::<Vec<_>>();

        let versions = config
            .versions
            .iter()
            .filter_map(|version| match TlsVersion::try_from(*version) {
                Ok(TlsVersion::TlsV12) => Some(&rustls::version::TLS12),
                Ok(TlsVersion::TlsV13) => Some(&rustls::version::TLS13),
                Ok(other_version) => {
                    error!(
                        "{} unsupported TLS version {:?}",
                        log_module_context!(),
                        other_version
                    );
                    None
                }
                Err(_) => {
                    error!("{} unsupported TLS version", log_module_context!());
                    None
                }
            })
            .collect::<Vec<_>>();

        let kx_groups = if config.groups_list.is_empty() {
            default_provider().kx_groups
        } else {
            config
                .groups_list
                .iter()
                .filter_map(|group| match kx_group_by_name(group) {
                    Some(kx) => Some(kx),
                    None => {
                        debug!("key exchange group {:?} not supported by the compiled crypto provider, skipping", group);
                        None
                    }
                })
                .collect::<Vec<_>>()
        };

        let provider = Arc::new(CryptoProvider {
            cipher_suites: ciphers,
            kx_groups,
            ..default_provider()
        });

        let builder = RustlsServerConfig::builder_with_provider(provider.clone())
            .with_protocol_versions(&versions[..])
            .map_err(|err| ListenerError::BuildRustls(err.to_string()))?;

        // mTLS: `client_auth` decodes to `ClientAuthMode` (NONE at field 0).
        // NONE keeps the historical `.with_no_client_auth()`; OPTIONAL and
        // REQUIRED install a WebPki client-certificate verifier built from the
        // listener's trusted CA bundle (and optional CRLs). OPTIONAL differs
        // only by allowing connections that present no certificate at all. The
        // verifier is built from the same `provider` as the server config so it
        // works in single-provider builds (`crypto-openssl`-only) and in
        // multi-provider builds (`--all-features`) where no process-default
        // provider is installed.
        let builder = match Self::client_cert_verifier(config, &provider)? {
            Some(verifier) => builder.with_client_cert_verifier(verifier),
            None => builder.with_no_client_auth(),
        };

        let mut server_config = builder.with_cert_resolver(resolver);
        server_config.send_tls13_tickets = config.send_tls13_tickets as usize;

        server_config.alpn_protocols = if config.alpn_protocols.is_empty() {
            DEFAULT_ALPN_PROTOCOLS
                .iter()
                .map(|p| p.as_bytes().to_vec())
                .collect()
        } else {
            config
                .alpn_protocols
                .iter()
                .map(|p| p.as_bytes().to_vec())
                .collect()
        };

        Ok(server_config)
    }

    /// Refuse two CRLs of one CA whose scopes overlap: webpki checks a
    /// certificate against the first configured CRL that is authoritative for
    /// it and never reads the others, so the order alone would decide, and an
    /// old CRL listed before its replacement would hide every revocation the
    /// replacement adds. A CRL without an `IssuingDistributionPoint` covers
    /// everything its CA issued; partitions of one CA, each with its own
    /// distribution point, do not overlap and are accepted together.
    ///
    /// Issuers and distribution points are compared as the raw DER webpki
    /// compares. The check does not depend on time, so every worker runs it
    /// when it builds the listener; [`Self::check_crls_current`] is the one
    /// that does.
    fn check_crl_set(crls: &[CertificateRevocationListDer<'_>]) -> Result<(), ListenerError> {
        let mut scopes: Vec<(Vec<u8>, Option<Vec<u8>>)> = Vec::with_capacity(crls.len());
        for (index, crl) in crls.iter().enumerate() {
            let parsed = webpki::BorrowedCertRevocationList::from_der(crl.as_ref())
                .map_err(|e| ListenerError::ClientAuth(format!("invalid CRL: {e}")))?;
            let parsed = webpki::CertRevocationList::from(parsed);
            let issuer = parsed.issuer().to_vec();
            let distribution_point = parsed.issuing_distribution_point().map(<[u8]>::to_vec);
            let overlapping = scopes.iter().position(|(seen_issuer, seen_point)| {
                *seen_issuer == issuer
                    && (seen_point.is_none()
                        || distribution_point.is_none()
                        || *seen_point == distribution_point)
            });
            if let Some(first) = overlapping {
                return Err(ListenerError::ClientAuth(format!(
                    "CRLs #{} and #{} (counted across client_ca_crls) are issued by the \
                     same CA for overlapping certificates, and only the first would be \
                     consulted: configure one CRL per issuer, or one per distribution point",
                    first + 1,
                    index + 1
                )));
            }
            scopes.push((issuer, distribution_point));
        }
        Ok(())
    }

    /// Refuse a CRL already past its `nextUpdate` at `now` (seconds since the
    /// Unix epoch): with revocation expiry enforced it would reject every
    /// client it covers, which is better reported when the operator states it
    /// than found at the first handshake.
    ///
    /// Main process only, on what an operator states (configuration load,
    /// reload, a client request), never on a replay or in a worker: a CRL
    /// that lapses while the listener runs must not stop a worker started
    /// later from building the listener, or the reload that brings a current
    /// CRL would find nothing to patch there. Such a worker builds it and
    /// rejects the clients at handshake until that reload.
    pub fn check_crls_current(crls: &[String], now: i64) -> Result<(), ListenerError> {
        let mut index = 0;
        for pem in crls {
            for crl in CertificateRevocationListDer::pem_slice_iter(pem.as_bytes()) {
                let crl =
                    crl.map_err(|e| ListenerError::ClientAuth(format!("invalid CRL PEM: {e}")))?;
                index += 1;
                if let Some(next_update) = sozu_command::certificate::crl_next_update(crl.as_ref())
                    && next_update <= now
                {
                    return Err(ListenerError::ClientAuth(format!(
                        "CRL #{index} (counted across client_ca_crls) expired {} seconds ago: \
                         its nextUpdate is past, refresh it",
                        now - next_update
                    )));
                }
            }
        }
        Ok(())
    }

    /// Check a client authentication policy the way a listener would build
    /// it, without a listener: the main process runs this on an
    /// `UpdateHttpsListenerConfig.client_auth_policy` patch before it commits
    /// the patch to its state, so a policy no worker could build is refused
    /// up front rather than fanned out.
    pub fn validate_client_auth_policy(policy: &ClientAuthPolicy) -> Result<(), ListenerError> {
        let mut config = HttpsListenerConfig::default();
        config.apply_client_auth_policy(policy);
        Self::client_cert_verifier(&config, &Arc::new(default_provider())).map(|_| ())
    }

    /// Build the rustls client-certificate verifier for a listener's mTLS
    /// configuration, or `None` when client auth is disabled.
    ///
    /// Returns `None` only for [`ClientAuthMode::ClientAuthNone`] (and for an
    /// absent `client_auth` field, which decodes to that variant), preserving
    /// the historical `.with_no_client_auth()` path. For OPTIONAL/REQUIRED it
    /// parses `client_ca_certificates` into a root store and, when present,
    /// `client_ca_crls` into revocation lists. OPTIONAL additionally allows
    /// unauthenticated clients (no certificate presented); REQUIRED aborts the
    /// handshake in that case.
    ///
    /// The verifier is built with the caller's `provider` so it never relies on
    /// a process-default crypto provider (which may be absent or ambiguous). An
    /// unknown `client_auth` value is rejected rather than treated as NONE, so a
    /// malformed or future enum value can never silently disable client auth.
    fn client_cert_verifier(
        config: &HttpsListenerConfig,
        provider: &Arc<CryptoProvider>,
    ) -> Result<Option<Arc<dyn rustls::server::danger::ClientCertVerifier>>, ListenerError> {
        // Reject unknown enum values instead of failing open to NONE.
        let raw = config
            .client_auth
            .unwrap_or(ClientAuthMode::ClientAuthNone as i32);
        let mode = ClientAuthMode::try_from(raw).map_err(|_| {
            ListenerError::ClientAuth(format!("unknown client_auth mode value {raw}"))
        })?;
        if mode == ClientAuthMode::ClientAuthNone {
            return Ok(None);
        }

        // Parse every trusted-CA PEM entry into the root store. Each entry may
        // itself hold a concatenated PEM chain, so iterate per entry. An entry
        // that contributes no certificate (empty text, or PEM carrying another
        // section type) is rejected rather than skipped: it would start the
        // listener with only a subset of the configured trust anchors, so
        // clients issued by the omitted CA would fail with no visible cause.
        let mut roots = RootCertStore::empty();
        for pem in &config.client_ca_certificates {
            let before = roots.len();
            for cert in CertificateDer::pem_slice_iter(pem.as_bytes()) {
                let cert =
                    cert.map_err(|e| ListenerError::ClientAuth(format!("invalid CA PEM: {e}")))?;
                roots
                    .add(cert)
                    .map_err(|e| ListenerError::ClientAuth(format!("untrusted CA: {e}")))?;
            }
            if roots.len() == before {
                return Err(ListenerError::ClientAuth(
                    "a configured trusted-CA entry contained no certificate".to_owned(),
                ));
            }
        }
        if roots.is_empty() {
            return Err(ListenerError::ClientAuth(
                "client auth requested but no trusted CA certificate was provided".to_owned(),
            ));
        }

        // Parse CRLs per configured entry. An entry that yields zero CRLs (empty
        // text, or PEM carrying another section type) is a misconfiguration: it
        // would silently disable revocation, so reject it rather than build a
        // verifier that skips `with_crls`.
        let mut crls = Vec::new();
        for pem in &config.client_ca_crls {
            let before = crls.len();
            for crl in CertificateRevocationListDer::pem_slice_iter(pem.as_bytes()) {
                crls.push(
                    crl.map_err(|e| ListenerError::ClientAuth(format!("invalid CRL PEM: {e}")))?,
                );
            }
            if crls.len() == before {
                return Err(ListenerError::ClientAuth(
                    "a configured CRL entry contained no certificate revocation list".to_owned(),
                ));
            }
        }
        Self::check_crl_set(&crls)?;

        let mut builder =
            WebPkiClientVerifier::builder_with_provider(Arc::new(roots), provider.clone());
        if !crls.is_empty() {
            // rustls defaults to `ExpirationPolicy::Ignore`, which keeps trusting
            // a CRL past its `nextUpdate`. Enforce expiration so a stale CRL is
            // rejected rather than silently accepting certificates whose
            // revocation status is no longer known.
            builder = builder.with_crls(crls).enforce_revocation_expiration();
        }
        if mode == ClientAuthMode::ClientAuthOptional {
            builder = builder.allow_unauthenticated();
        }
        let verifier = builder
            .build()
            .map_err(|e| ListenerError::ClientAuth(e.to_string()))?;
        Ok(Some(verifier))
    }

    /// Apply a partial-update patch to this listener's live configuration.
    ///
    /// Fields absent in the patch (i.e. `None`) are preserved unchanged.
    /// If `alpn_protocols` is present the rustls `ServerConfig` is rebuilt —
    /// in-flight handshakes keep the old Arc; new ones see the new one.
    /// If `http_answers` is present only the listener-default templates are
    /// replaced; per-cluster overrides in `cluster_custom_answers` are kept.
    ///
    /// All-or-nothing (sozu-proxy/sozu#1703): the patch is validated, then
    /// applied to a copy of the configuration, and every fallible artifact
    /// (the rustls context, the answer registry) is built from that copy.
    /// Only once all of it succeeded are the copy and the artifacts
    /// committed and the inheriting frontends' HSTS refreshed, so a refused
    /// patch leaves the listener exactly as it was. The copy is one
    /// `HttpsListenerConfig` clone per patch, on the command path only.
    pub fn update_config(
        &mut self,
        patch: &UpdateHttpsListenerConfig,
    ) -> Result<(), ListenerError> {
        // Defense-in-depth validation: main-process ConfigState::dispatch
        // validates before scatter, but a raw protobuf client or state replay
        // may reach the worker without that check. `StateError` lifts into
        // `ListenerError` via `From` so `?` suffices. The main process runs
        // the same checks (`ConfigState::update_https_listener` and, for the
        // templates, `validate_listener_request` in
        // `bin/src/command/requests.rs`), so both refuse the same patches.
        validate_h2_flood_knobs_https(patch)?;
        if let Some(ref alpn) = patch.alpn_protocols {
            validate_alpn_protocols(&alpn.values)?;
        }
        if let Some(ref hdr) = patch.sozu_id_header {
            validate_sozu_id_header(hdr)?;
        }
        if let Some(v) = patch.forwarded_headers {
            validate_forwarded_headers(v)?;
        }
        // HSTS is a full-object replacement, and `enabled` is the explicit
        // disambiguator between "disable" and "enable" semantics: the
        // operator must signal one or the other on every update, so a block
        // without it is refused. The main process refuses it too, with
        // `StateError::InvalidValue` (`validate_hsts_patch`,
        // `command/src/state.rs`).
        if patch.hsts.is_some_and(|hsts| hsts.enabled.is_none()) {
            return Err(ListenerError::HstsEnabledRequired);
        }
        HttpAnswers::validate_patch_templates(patch.http_answers.as_ref(), &patch.answers)
            .map_err(|(name, error)| ListenerError::TemplateParse(name, error))?;

        let mut config = self.config.clone();

        // --- simple field patches ---
        if let Some(v) = patch.public_address {
            config.public_address = Some(v);
        }
        if let Some(v) = patch.expect_proxy {
            config.expect_proxy = v;
        }
        if let Some(ref v) = patch.sticky_name {
            config.sticky_name = v.to_owned();
        }
        if let Some(v) = patch.front_timeout {
            config.front_timeout = v;
        }
        if let Some(v) = patch.back_timeout {
            config.back_timeout = v;
        }
        if let Some(v) = patch.connect_timeout {
            config.connect_timeout = v;
        }
        if let Some(v) = patch.request_timeout {
            config.request_timeout = v;
        }
        if let Some(v) = patch.strict_sni_binding {
            config.strict_sni_binding = Some(v);
        }
        if let Some(v) = patch.disable_http11 {
            config.disable_http11 = Some(v);
        }
        if let Some(ref v) = patch.sozu_id_header {
            config.sozu_id_header = Some(v.to_owned());
        }
        if let Some(v) = patch.elide_x_real_ip {
            config.elide_x_real_ip = Some(v);
        }
        if let Some(v) = patch.send_x_real_ip {
            config.send_x_real_ip = Some(v);
        }
        if let Some(v) = patch.forwarded_headers {
            config.forwarded_headers = Some(v);
        }

        // --- H2 flood knobs ---
        if let Some(v) = patch.h2_max_rst_stream_per_window {
            config.h2_max_rst_stream_per_window = Some(v);
        }
        if let Some(v) = patch.h2_max_ping_per_window {
            config.h2_max_ping_per_window = Some(v);
        }
        if let Some(v) = patch.h2_max_settings_per_window {
            config.h2_max_settings_per_window = Some(v);
        }
        if let Some(v) = patch.h2_max_empty_data_per_window {
            config.h2_max_empty_data_per_window = Some(v);
        }
        if let Some(v) = patch.h2_max_continuation_frames {
            config.h2_max_continuation_frames = Some(v);
        }
        if let Some(v) = patch.h2_max_glitch_count {
            config.h2_max_glitch_count = Some(v);
        }
        if let Some(v) = patch.h2_initial_connection_window {
            config.h2_initial_connection_window = Some(v);
        }
        if let Some(v) = patch.h2_max_concurrent_streams {
            config.h2_max_concurrent_streams = Some(v);
        }
        if let Some(v) = patch.h2_stream_shrink_ratio {
            config.h2_stream_shrink_ratio = Some(v);
        }
        if let Some(v) = patch.h2_max_rst_stream_lifetime {
            config.h2_max_rst_stream_lifetime = Some(v);
        }
        if let Some(v) = patch.h2_max_rst_stream_abusive_lifetime {
            config.h2_max_rst_stream_abusive_lifetime = Some(v);
        }
        if let Some(v) = patch.h2_max_rst_stream_emitted_lifetime {
            config.h2_max_rst_stream_emitted_lifetime = Some(v);
        }
        if let Some(v) = patch.h2_max_header_list_size {
            config.h2_max_header_list_size = Some(v);
        }
        if let Some(v) = patch.h2_max_header_table_size {
            config.h2_max_header_table_size = Some(v);
        }
        if let Some(v) = patch.h2_max_header_fields {
            config.h2_max_header_fields = Some(v);
        }
        if let Some(v) = patch.h2_stream_refusal_percent {
            config.h2_stream_refusal_percent = Some(v);
        }
        if let Some(v) = patch.h2_stream_idle_timeout_seconds {
            config.h2_stream_idle_timeout_seconds = Some(v);
        }
        if let Some(v) = patch.h2_graceful_shutdown_deadline_seconds {
            config.h2_graceful_shutdown_deadline_seconds = Some(v);
        }
        if let Some(v) = patch.h2_max_window_update_stream0_per_window {
            config.h2_max_window_update_stream0_per_window = Some(v);
        }

        if let Some(new_hsts) = patch.hsts {
            config.hsts = Some(new_hsts);
        }
        if let Some(ref alpn_wrapper) = patch.alpn_protocols {
            // Empty values vec = reset to default (runtime treats empty as default)
            config.alpn_protocols = alpn_wrapper.values.clone();
        }
        if let Some(ref policy) = patch.client_auth_policy {
            config.apply_client_auth_policy(policy);
        }

        // --- ALPN rebuild (may force a rustls ServerConfig rebuild) ---
        //
        // Built from the candidate config, which carries the new ALPN, and
        // published below only once every other fallible step succeeded, so
        // a rustls failure (crypto provider transient, resolver error, etc.)
        // leaves the listener observably unchanged. The main-process state
        // would still diverge from that worker-side refusal: the main process
        // cannot build this worker's rustls context before it commits.
        // A client authentication policy lives in the rustls context's client
        // certificate verifier, so a new policy needs the same rebuild; an
        // invalid one fails it here and the listener keeps its old policy.
        let new_rustls = if patch.alpn_protocols.is_some() || patch.client_auth_policy.is_some() {
            Some(Arc::new(Self::create_rustls_context(
                &config,
                self.resolver.clone(),
            )?))
        } else {
            None
        };

        // HTTP answers: merge legacy `http_answers` and the new `answers`
        // map on top of the candidate config, then build the listener-level
        // template registry from it. It is fallible, so it is built here and
        // published below with the config, never before.
        let answers_changed = patch.http_answers.is_some() || !patch.answers.is_empty();
        let rebuilt = if answers_changed {
            if let Some(ref new_answers) = patch.http_answers {
                crate::sozu_command::state::merge_custom_http_answers(
                    &mut config.http_answers,
                    new_answers,
                );
            }
            for (code, body) in &patch.answers {
                if !body.is_empty() {
                    config.answers.insert(code.clone(), body.clone());
                }
            }

            let mut answers_map = config.answers.clone();
            if let Some(ref legacy) = config.http_answers {
                crate::protocol::http::answers::merge_legacy_into_map(&mut answers_map, legacy);
            }
            Some(
                HttpAnswers::new(&answers_map)
                    .map_err(|(name, error)| ListenerError::TemplateParse(name, error))?,
            )
        } else {
            None
        };

        // Commit: nothing below can fail.
        self.config = config;
        if let Some(new_rustls) = new_rustls {
            self.rustls_details = new_rustls;
        }
        if let Some(alpn_wrapper) = &patch.alpn_protocols {
            // Post: the live config must now name exactly the patched ALPN
            // set. New handshakes negotiate against this set, so the
            // `upgrade_handshake` "protocol ∈ configured ALPN" property is
            // anchored to what we just stored.
            debug_assert_eq!(
                self.config.alpn_protocols, alpn_wrapper.values,
                "committed ALPN config must match the patch values exactly"
            );
        }
        if let Some(mut rebuilt) = rebuilt {
            // The rebuilt registry is PUBLISHED under a new `Rc`, not written
            // through the old one. Every request already in flight captured
            // the old handle when it arrived (`mux::Context::create_stream`)
            // and renders its default answers from that, so a reload landing
            // mid-request cannot change the page that request is about to
            // emit; requests arriving after this point capture the new handle.
            // That is the one-request staleness window of
            // `lib/src/protocol/mux/LIFECYCLE.md` §2.5.
            //
            // The per-cluster overrides are therefore COPIED, not
            // `mem::take`n: taking them would empty the registry those
            // in-flight requests still hold and strip their cluster templates
            // mid-response. The copy is a map clone over `Rc<Template>`, so
            // both registries share the compiled templates themselves.
            rebuilt.cluster_answers = self.answers.borrow().cluster_answers.clone();
            self.answers = Rc::new(RefCell::new(rebuilt));
        }

        // HSTS: full-object replacement when present in the patch (stored
        // into the candidate config above; a block without `enabled` was
        // refused before the first write). Absent patch field preserves
        // current value (matches the rest of this partial-update handler).
        //
        // Inheriting frontends are refreshed in place via
        // `Router::refresh_inheriting_hsts`: every frontend that declared no
        // `hsts` of its own at add time
        // (`Frontend.inherits_listener_hsts == true`) gets its
        // `headers_response` re-materialised against the new value.
        // Explicit per-frontend overrides
        // (`inherits_listener_hsts == false`) are untouched. The
        // `http.hsts.listener_default_patched` counter still fires so
        // dashboards can correlate patches with the new
        // `http.hsts.frontend_refreshed` counter (sum of refreshed
        // frontends from this patch).
        if patch.hsts.is_some() {
            let refreshed = self
                .fronts
                .refresh_inheriting_hsts(self.config.hsts.as_ref());
            for _ in 0..refreshed {
                crate::incr!(names::http::HSTS_FRONTEND_REFRESHED);
            }
            info!(
                "{} HTTPS listener {:?} HSTS default patched; refreshed {} inheriting \
                 frontend(s). Explicit per-frontend overrides untouched.",
                log_module_context!(),
                self.config.address,
                refreshed,
            );
            crate::incr!(names::http::HSTS_LISTENER_DEFAULT_PATCHED);
        }

        Ok(())
    }

    pub fn add_https_front(&mut self, tls_front: HttpFrontend) -> Result<(), ListenerError> {
        self.add_https_front_with_hsts_origin(tls_front, crate::router::HstsOrigin::Explicit)
    }

    /// Variant of [`Self::add_https_front`] that records the origin of
    /// `tls_front.hsts` so listener-default patches can reflow inheriting
    /// frontends without disturbing explicit per-frontend overrides. The
    /// caller passes [`crate::router::HstsOrigin::InheritedFromListenerDefault`] when
    /// the value was filled in from `self.config.hsts` rather than from
    /// the operator's per-frontend configuration.
    pub fn add_https_front_with_hsts_origin(
        &mut self,
        tls_front: HttpFrontend,
        hsts_origin: crate::router::HstsOrigin,
    ) -> Result<(), ListenerError> {
        self.fronts
            .add_http_front_with_hsts_origin(&tls_front, hsts_origin)
            .map_err(ListenerError::AddFrontend)
    }

    pub fn remove_https_front(&mut self, tls_front: HttpFrontend) -> Result<(), ListenerError> {
        debug!(
            "{} removing tls_front {:?}",
            log_module_context!(),
            tls_front
        );
        self.fronts
            .remove_http_front(&tls_front)
            .map_err(ListenerError::RemoveFrontend)
    }

    fn accept(&mut self) -> Result<(MioTcpStream, StdSocketAddr), AcceptError> {
        if let Some(ref sock) = self.listener {
            match sock.accept() {
                Ok((frontend_sock, peer)) => {
                    if self.nodelay_backlog
                        && let Err(e) = frontend_sock.set_nodelay(true)
                    {
                        error!(
                            "{} error setting nodelay on front socket({:?}): {:?}",
                            log_module_context!(),
                            frontend_sock,
                            e
                        );
                    }
                    Ok((frontend_sock, peer))
                }
                Err(e) if e.kind() == ErrorKind::WouldBlock => {
                    // The backlog queued before `activate()` is drained.
                    self.nodelay_backlog = false;
                    Err(AcceptError::WouldBlock)
                }
                Err(e) => {
                    error!("{} accept() IO error: {:?}", log_module_context!(), e);
                    Err(AcceptError::IoError)
                }
            }
        } else {
            error!(
                "{} cannot accept connections, no listening socket available",
                log_module_context!()
            );
            Err(AcceptError::IoError)
        }
    }
}

pub struct HttpsProxy {
    listeners: HashMap<Token, Rc<RefCell<HttpsListener>>>,
    clusters: HashMap<ClusterId, Cluster>,
    backends: Rc<RefCell<BackendMap>>,
    pool: Rc<RefCell<Pool>>,
    registry: Registry,
    sessions: Rc<RefCell<SessionManager>>,
}

impl HttpsProxy {
    pub fn new(
        registry: Registry,
        sessions: Rc<RefCell<SessionManager>>,
        pool: Rc<RefCell<Pool>>,
        backends: Rc<RefCell<BackendMap>>,
    ) -> HttpsProxy {
        HttpsProxy {
            listeners: HashMap::new(),
            clusters: HashMap::new(),
            backends,
            pool,
            registry,
            sessions,
        }
    }

    pub fn add_listener(
        &mut self,
        config: HttpsListenerConfig,
        token: Token,
    ) -> Result<Token, ProxyError> {
        if self.listeners.contains_key(&token) {
            return Err(ProxyError::ListenerAlreadyPresent);
        }
        let mut https_listener =
            HttpsListener::try_new(config, token).map_err(ProxyError::AddListener)?;
        // Frontends and certificates name their listener by address alone, so
        // a listener added next to one already on its address (on another
        // interface) takes over the routes and certificates that one serves:
        // every listener on an address holds the same ones, whenever it was
        // added (sozu-proxy/sozu#719). The certificates are copied into this
        // listener's own resolver, the one its rustls configuration already
        // points at, so later changes keep reaching it through the fan-out.
        if let Some(sibling) = self
            .listeners_at(https_listener.address)
            .ok()
            .and_then(|listeners| listeners.into_iter().next())
        {
            let sibling = sibling.borrow();
            https_listener.fronts = sibling.fronts.clone();
            // Frontends that declared no `hsts` of their own inherit this
            // listener's default instead of the sibling's, whether or not the
            // sibling had one (sozu-proxy/sozu#1691).
            https_listener
                .fronts
                .refresh_inheriting_hsts(https_listener.config.hsts.as_ref());
            https_listener.tags = sibling.tags.clone();
            let certificates = sibling
                .resolver
                .0
                .lock()
                .map_err(|e| ProxyError::Lock(e.to_string()))?
                .clone();
            *https_listener
                .resolver
                .0
                .lock()
                .map_err(|e| ProxyError::Lock(e.to_string()))? = certificates;
        }
        match self.listeners.entry(token) {
            Entry::Vacant(entry) => {
                entry.insert(Rc::new(RefCell::new(https_listener)));
                Ok(token)
            }
            _ => Err(ProxyError::ListenerAlreadyPresent),
        }
    }

    pub fn remove_listener(
        &mut self,
        remove: RemoveListener,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        let len = self.listeners.len();

        let remove_address = remove.listener_key();
        self.listeners
            .retain(|_, listener| !listener.borrow().is(&remove_address));

        if !self.listeners.len() < len {
            info!(
                "{} no HTTPS listener to remove at address {}",
                log_module_context!(),
                remove_address
            )
        }
        Ok(None)
    }

    pub fn soft_stop(&mut self) -> Result<(), ProxyError> {
        let listeners = std::mem::take(&mut self.listeners);
        let mut socket_errors = vec![];
        for l in listeners.values() {
            if let Some(mut sock) = l.borrow_mut().listener.take() {
                debug!("{} deregistering socket {:?}", log_module_context!(), sock);
                if let Err(e) = self.registry.deregister(&mut sock) {
                    let error = format!("socket {sock:?}: {e:?}");
                    socket_errors.push(error);
                }
            }
        }

        if !socket_errors.is_empty() {
            return Err(ProxyError::SoftStop {
                proxy_protocol: "HTTPS".to_string(),
                error: format!("Error deregistering listen sockets: {socket_errors:?}"),
            });
        }

        Ok(())
    }

    pub fn hard_stop(&mut self) -> Result<(), ProxyError> {
        let mut listeners = std::mem::take(&mut self.listeners);
        let mut socket_errors = vec![];
        for (_, l) in listeners.drain() {
            if let Some(mut sock) = l.borrow_mut().listener.take() {
                debug!("{} deregistering socket {:?}", log_module_context!(), sock);
                if let Err(e) = self.registry.deregister(&mut sock) {
                    let error = format!("socket {sock:?}: {e:?}");
                    socket_errors.push(error);
                }
            }
        }

        if !socket_errors.is_empty() {
            return Err(ProxyError::HardStop {
                proxy_protocol: "HTTPS".to_string(),
                error: format!("Error deregistering listen sockets: {socket_errors:?}"),
            });
        }

        Ok(())
    }

    pub fn query_all_certificates(&mut self) -> Result<Option<ResponseContent>, ProxyError> {
        let certificates = self
            .listeners
            .values()
            .map(|listener| {
                let owned = listener.borrow();
                // Same handling as the `add`/`remove`/`replace` siblings: a
                // poisoned resolver is reported as `ProxyError::Lock`, never
                // unwrapped. A read-only query must not be the one control-
                // plane request that kills the worker.
                let resolver = owned
                    .resolver
                    .0
                    .lock()
                    .map_err(|e| ProxyError::Lock(e.to_string()))?;
                let certificate_summaries = resolver
                    .domains
                    .to_hashmap()
                    .drain()
                    .map(|(k, fingerprint)| CertificateSummary {
                        domain: certificate_summary_domain(&k),
                        fingerprint: fingerprint.to_string(),
                    })
                    .collect();

                Ok(CertificatesByAddress {
                    address: owned.address.into(),
                    certificate_summaries,
                })
            })
            .collect::<Result<Vec<CertificatesByAddress>, ProxyError>>()?;

        let listeners_count = certificates.len();
        let certificates_count = certificates
            .iter()
            .map(|entry| entry.certificate_summaries.len())
            .fold(0usize, |total, count| total.saturating_add(count));

        info!(
            "{} got Certificates::All query, listeners_count={} certificates_count={}",
            log_module_context!(),
            listeners_count,
            certificates_count,
        );

        Ok(Some(
            ContentType::CertificatesByAddress(ListOfCertificatesByAddress { certificates }).into(),
        ))
    }

    pub fn query_certificate_for_domain(
        &mut self,
        domain: String,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        // The resolver keys its SNI trie on ASCII-lowercased certificate
        // names (`CertifiedKeyWrapper::try_from`), because that is the
        // only form rustls ever asks it for. An operator query has to
        // ask the same question a handshake does, or
        // `sozu query certificates --domain Example.COM` reports the
        // certificate missing while the proxy happily serves it.
        let domain_key = domain.to_ascii_lowercase();
        let certificates = self
            .listeners
            .values()
            .map(|listener| {
                let owned = listener.borrow();
                // See `query_all_certificates`: lock like the
                // `add`/`remove`/`replace` siblings do.
                let resolver = owned
                    .resolver
                    .0
                    .lock()
                    .map_err(|e| ProxyError::Lock(e.to_string()))?;
                let mut certificate_summaries = vec![];

                if let Some((k, fingerprint)) = resolver.domain_lookup(domain_key.as_bytes(), true)
                {
                    certificate_summaries.push(CertificateSummary {
                        domain: certificate_summary_domain(k),
                        fingerprint: fingerprint.to_string(),
                    });
                }
                Ok(CertificatesByAddress {
                    address: owned.address.into(),
                    certificate_summaries,
                })
            })
            .collect::<Result<Vec<CertificatesByAddress>, ProxyError>>()?;

        let listeners_count = certificates.len();
        let certificates_count = certificates
            .iter()
            .map(|entry| entry.certificate_summaries.len())
            .fold(0usize, |total, count| total.saturating_add(count));

        info!(
            "{} got Certificates::Domain query, domain_bytes={} listeners_count={} certificates_count={}",
            log_module_context!(),
            domain.len(),
            listeners_count,
            certificates_count,
        );

        Ok(Some(
            ContentType::CertificatesByAddress(ListOfCertificatesByAddress { certificates }).into(),
        ))
    }

    /// What this proxy would do with a socket handed to
    /// [`activate_listener`](Self::activate_listener) for `addr`. See
    /// [`crate::InheritedSocketFate`].
    ///
    /// The event loop is single-threaded, so nothing can change the listener's
    /// `active` flag between this answer and the `activate_listener` call that
    /// acts on it.
    pub fn inherited_socket_fate(&self, addr: &ListenerKey) -> crate::InheritedSocketFate {
        use crate::InheritedSocketFate;
        match self
            .listeners
            .values()
            .find(|listener| listener.borrow().is(addr))
        {
            None => InheritedSocketFate::Unclaimed,
            Some(listener) if listener.borrow().active => InheritedSocketFate::Refused,
            Some(_) => InheritedSocketFate::Adopted,
        }
    }

    pub fn activate_listener(
        &mut self,
        addr: &ListenerKey,
        tcp_listener: Option<MioTcpListener>,
    ) -> Result<Token, ProxyError> {
        let listener = self
            .listeners
            .values()
            .find(|listener| listener.borrow().is(addr))
            .ok_or(ProxyError::NoListenerFound(addr.clone()))?;

        listener
            .borrow_mut()
            .activate(&self.registry, tcp_listener)
            .map_err(|listener_error| ProxyError::ListenerActivation {
                address: addr.address,
                listener_error,
            })
    }

    /// The slab token reserved for the listener at `address`, if this proxy
    /// holds one.
    ///
    /// A listener owns exactly one slab slot for its whole `AddListener` ->
    /// `RemoveListener` lifetime, and no `remove_listener` implementation
    /// touches the session slab. `Server` therefore reads the token here
    /// BEFORE dropping the listener, so that reserved slot is released exactly
    /// once, at the end of the lifetime.
    pub fn listener_token(&self, address: &ListenerKey) -> Option<Token> {
        self.listeners
            .iter()
            .find(|(_, listener)| listener.borrow().is(address))
            .map(|(token, _)| *token)
    }

    pub fn give_back_listeners(&mut self) -> Vec<(ListenerKey, MioTcpListener)> {
        self.listeners
            .values()
            .filter_map(|listener| {
                let mut owned = listener.borrow_mut();
                if let Some(listener) = owned.listener.take() {
                    // Reset `active` so a subsequent `activate()` re-binds
                    // instead of short-circuiting on the stale flag.
                    owned.active = false;
                    return Some((owned.key(), listener));
                }

                None
            })
            .collect()
    }

    pub fn give_back_listener(
        &mut self,
        address: &ListenerKey,
    ) -> Result<(Token, MioTcpListener), ProxyError> {
        let listener = self
            .listeners
            .values()
            .find(|listener| listener.borrow().is(address))
            .ok_or(ProxyError::NoListenerFound(address.clone()))?;

        let mut owned = listener.borrow_mut();

        let taken_listener = owned
            .listener
            .take()
            .ok_or(ProxyError::UnactivatedListener)?;

        // Reset `active` so a subsequent `activate()` re-binds instead of
        // short-circuiting on the stale flag.
        owned.active = false;

        Ok((owned.token, taken_listener))
    }

    /// Every listener on `address`, whatever its interface. Frontends and
    /// certificates name their listener by address alone, so they apply to
    /// all the listeners sharing that address on different interfaces.
    fn listeners_at(
        &self,
        address: StdSocketAddr,
    ) -> Result<Vec<Rc<RefCell<HttpsListener>>>, ProxyError> {
        let mut listeners: Vec<_> = self
            .listeners
            .iter()
            .filter(|(_, listener)| listener.borrow().address == address)
            .map(|(token, listener)| (*token, listener.clone()))
            .collect();
        // Token order, so a failure is reported the same way on every run.
        listeners.sort_by_key(|(token, _)| *token);
        let listeners: Vec<_> = listeners
            .into_iter()
            .map(|(_, listener)| listener)
            .collect();
        if listeners.is_empty() {
            return Err(ProxyError::NoListenerFound(address.into()));
        }
        Ok(listeners)
    }

    /// Apply a partial-update patch to the identified HTTPS listener.
    pub fn update_listener(&mut self, patch: UpdateHttpsListenerConfig) -> Result<(), ProxyError> {
        let address: std::net::SocketAddr = patch.address.into();
        let listener = self
            .listeners
            .values()
            .find(|l| l.borrow().address == address)
            .ok_or(ProxyError::NoListenerFound(address.into()))?;
        listener
            .borrow_mut()
            .update_config(&patch)
            .map_err(|listener_error| ProxyError::ListenerActivation {
                address,
                listener_error,
            })
    }

    pub fn add_cluster(
        &mut self,
        mut cluster: Cluster,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        let mut cluster_overrides = cluster.answers.clone();
        if let Some(answer_503) = cluster.answer_503.take() {
            cluster_overrides
                .entry("503".to_owned())
                .or_insert(answer_503);
        }
        if !cluster_overrides.is_empty() {
            for listener in self.listeners.values() {
                listener
                    .borrow()
                    .answers
                    .borrow_mut()
                    .add_cluster_answers(&cluster.cluster_id, &cluster_overrides)
                    .map_err(|(status, error)| {
                        ProxyError::AddCluster(ListenerError::TemplateParse(status, error))
                    })?;
            }
        }
        self.clusters
            .insert(cluster.cluster_id.as_str().into(), cluster);
        Ok(None)
    }

    pub fn remove_cluster(
        &mut self,
        cluster_id: &str,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        self.clusters.remove(cluster_id);
        for listener in self.listeners.values() {
            listener
                .borrow()
                .answers
                .borrow_mut()
                .remove_cluster_answers(cluster_id);
        }

        Ok(None)
    }

    pub fn add_https_frontend(
        &mut self,
        front: RequestHttpFrontend,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        let front = front.clone().to_frontend().map_err(|request_error| {
            ProxyError::WrongInputFrontend {
                front: Box::new(front),
                error: request_error.to_string(),
            }
        })?;

        for listener in self.listeners_at(front.address)? {
            let mut listener = listener.borrow_mut();
            let mut front = front.clone();

            // ── HSTS listener-default → frontend inheritance ─────────────────
            // When the frontend declares no `hsts` block, fall back to the
            // listener default so the operator can opt into HSTS once at the
            // listener and have every HTTPS frontend inherit it.
            // `enabled = Some(false)` on the frontend is the explicit-disable
            // signal: it stays as-is and suppresses the inherited default.
            //
            // The `hsts_origin` flag records the frontend's own intent — it
            // declared no `hsts` — rather than whether a default existed, so
            // the resulting `Frontend` carries the inheritance bit even when
            // the listener has no default yet. A later
            // `UpdateHttpsListenerConfig.hsts` patch, or the copy into a
            // listener added on the same address (`HttpsProxy::add_listener`), then
            // resolves it against that listener's own default via
            // `Router::refresh_inheriting_hsts` without disturbing explicit
            // per-frontend overrides (sozu-proxy/sozu#1691).
            let hsts_origin = if front.hsts.is_none() {
                front.hsts = listener.config.hsts;
                crate::router::HstsOrigin::InheritedFromListenerDefault
            } else {
                crate::router::HstsOrigin::Explicit
            };

            listener.set_tags(front.hostname.to_owned(), front.tags.to_owned());
            listener
                .add_https_front_with_hsts_origin(front, hsts_origin)
                .map_err(ProxyError::AddFrontend)?;
        }
        Ok(None)
    }

    pub fn remove_https_frontend(
        &mut self,
        front: RequestHttpFrontend,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        let front = front.clone().to_frontend().map_err(|request_error| {
            ProxyError::WrongInputFrontend {
                front: Box::new(front),
                error: request_error.to_string(),
            }
        })?;

        // Every listener on the address drops the route, even when another
        // one fails: a sibling must never keep a route the others removed.
        // The first failure, in token order, is the one reported.
        let mut result = Ok(None);
        for listener in self.listeners_at(front.address)? {
            let mut listener = listener.borrow_mut();
            let hostname = front.hostname.to_owned();

            if let Err(error) = listener.remove_https_front(front.clone())
                && result.is_ok()
            {
                result = Err(ProxyError::RemoveFrontend(error));
            }

            if !listener.fronts.has_hostname(&hostname) {
                listener.set_tags(hostname, None);
            }
        }
        result
    }

    pub fn add_certificate(
        &mut self,
        add_certificate: AddCertificate,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        let address = add_certificate.address.into();

        for listener in self.listeners_at(address)? {
            let listener = listener.borrow();
            let mut resolver = listener
                .resolver
                .0
                .lock()
                .map_err(|e| ProxyError::Lock(e.to_string()))?;

            resolver
                .add_certificate(&add_certificate)
                .map_err(ProxyError::AddCertificate)?;
        }

        Ok(None)
    }

    //FIXME: should return an error if certificate still has fronts referencing it
    pub fn remove_certificate(
        &mut self,
        remove_certificate: RemoveCertificate,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        let address = remove_certificate.address.into();

        let fingerprint = Fingerprint(
            hex::decode(&remove_certificate.fingerprint)
                .map_err(ProxyError::WrongCertificateFingerprint)?,
        );

        // Every listener on the address applies the change, even when another
        // one fails, so none keeps a certificate its siblings dropped; the
        // first failure, in token order, is the one reported.
        let mut result = Ok(None);
        for listener in self.listeners_at(address)? {
            let listener = listener.borrow();
            let applied = listener
                .resolver
                .0
                .lock()
                .map_err(|e| ProxyError::Lock(e.to_string()))
                .and_then(|mut resolver| {
                    resolver
                        .remove_certificate(&fingerprint)
                        .map_err(ProxyError::RemoveCertificate)
                });
            if let Err(error) = applied
                && result.is_ok()
            {
                result = Err(error);
            }
        }
        result
    }

    //FIXME: should return an error if certificate still has fronts referencing it
    pub fn replace_certificate(
        &mut self,
        replace_certificate: ReplaceCertificate,
    ) -> Result<Option<ResponseContent>, ProxyError> {
        let address = replace_certificate.address.into();

        // Every listener on the address applies the change, even when another
        // one fails, so none keeps a certificate its siblings dropped; the
        // first failure, in token order, is the one reported.
        let mut result = Ok(None);
        for listener in self.listeners_at(address)? {
            let listener = listener.borrow();
            let applied = listener
                .resolver
                .0
                .lock()
                .map_err(|e| ProxyError::Lock(e.to_string()))
                .and_then(|mut resolver| {
                    resolver
                        .replace_certificate(&replace_certificate)
                        .map_err(ProxyError::ReplaceCertificate)
                });
            if let Err(error) = applied
                && result.is_ok()
            {
                result = Err(error);
            }
        }
        result
    }
}

impl ProxyConfiguration for HttpsProxy {
    fn accept(&mut self, token: ListenToken) -> Result<(MioTcpStream, StdSocketAddr), AcceptError> {
        match self.listeners.get(&Token(token.0)) {
            Some(listener) => listener.borrow_mut().accept(),
            None => Err(AcceptError::IoError),
        }
    }

    fn create_session(
        &mut self,
        mut frontend_sock: MioTcpStream,
        peer: StdSocketAddr,
        token: ListenToken,
        wait_time: Duration,
        proxy: Rc<RefCell<Self>>,
    ) -> Result<(), AcceptError> {
        let listener = self
            .listeners
            .get(&Token(token.0))
            .ok_or(AcceptError::IoError)?;
        // No `set_nodelay` here: the socket has `TCP_NODELAY` from its
        // listener, or from `HttpsListener::accept` if it was queued before
        // the listener set it.

        let owned = listener.borrow();
        let rustls_details = ServerConnection::new(owned.rustls_details.clone()).map_err(|e| {
            error!(
                "{} failed to create server session: {:?}",
                log_module_context!(),
                e
            );
            AcceptError::IoError
        })?;

        let mut session_manager = self.sessions.borrow_mut();
        let entry = session_manager.slab.vacant_entry();
        let session_token = Token(entry.key());
        // The session token IS the slab key: the event loop later indexes the
        // slab directly by the mio `Token` it receives, so any divergence here
        // would route readiness to the wrong session slot. Snapshot the key to
        // re-check after `entry.insert` consumes the entry.
        debug_assert_eq!(
            session_token.0,
            entry.key(),
            "HTTPS session token must equal its slab key"
        );

        self.registry
            .register(
                &mut frontend_sock,
                session_token,
                Interest::READABLE | Interest::WRITABLE,
            )
            .map_err(|register_error| {
                error!(
                    "{} error registering front socket({:?}): {:?}",
                    log_module_context!(),
                    frontend_sock,
                    register_error
                );
                AcceptError::RegisterError
            })?;

        let public_address: StdSocketAddr = match owned.config.public_address {
            Some(pub_addr) => pub_addr.into(),
            None => owned.config.address.into(),
        };

        let session = Rc::new(RefCell::new(HttpsSession::new(
            Duration::from_secs(owned.config.back_timeout as u64),
            Duration::from_secs(owned.config.connect_timeout as u64),
            Duration::from_secs(owned.config.front_timeout as u64),
            Duration::from_secs(owned.config.request_timeout as u64),
            owned.config.expect_proxy,
            listener.clone(),
            Rc::downgrade(&self.pool),
            proxy,
            public_address,
            rustls_details,
            frontend_sock,
            peer,
            session_token,
            wait_time,
        )));
        // The freshly built session must own exactly the token it is filed under,
        // so event-loop dispatch (slab key → session) and self-removal
        // (`frontend_token()` → slab key) agree.
        debug_assert_eq!(
            session.borrow().frontend_token(),
            session_token,
            "stored HTTPS session must report the slab token as its frontend token"
        );
        entry.insert(session);

        Ok(())
    }

    fn notify(&mut self, request: WorkerRequest) -> WorkerResponse {
        let request_id = request.id.clone();

        let request_type = match request.content.request_type {
            Some(t) => t,
            None => return WorkerResponse::error(request_id, "Empty request"),
        };

        let content_result = match request_type {
            RequestType::AddCluster(cluster) => {
                debug!(
                    "{} {} add cluster {:?}",
                    log_module_context!(),
                    request_id,
                    cluster
                );
                self.add_cluster(cluster)
            }
            RequestType::RemoveCluster(cluster_id) => {
                debug!(
                    "{} {} remove cluster {:?}",
                    log_module_context!(),
                    request_id,
                    cluster_id
                );
                self.remove_cluster(&cluster_id)
            }
            RequestType::AddHttpsFrontend(front) => {
                debug!(
                    "{} {} add https front {:?}",
                    log_module_context!(),
                    request_id,
                    front
                );
                self.add_https_frontend(front)
            }
            RequestType::RemoveHttpsFrontend(front) => {
                debug!(
                    "{} {} remove https front {:?}",
                    log_module_context!(),
                    request_id,
                    front
                );
                self.remove_https_frontend(front)
            }
            RequestType::AddCertificate(add_certificate) => {
                debug!(
                    "{} {} add certificate: {:?}",
                    log_module_context!(),
                    request_id,
                    add_certificate
                );
                self.add_certificate(add_certificate)
            }
            RequestType::RemoveCertificate(remove_certificate) => {
                debug!(
                    "{} {} remove certificate: {:?}",
                    log_module_context!(),
                    request_id,
                    remove_certificate
                );
                self.remove_certificate(remove_certificate)
            }
            RequestType::ReplaceCertificate(replace_certificate) => {
                debug!(
                    "{} {} replace certificate: {:?}",
                    log_module_context!(),
                    request_id,
                    replace_certificate
                );
                self.replace_certificate(replace_certificate)
            }
            RequestType::RemoveListener(remove) => {
                debug!(
                    "{} removing HTTPS listener at address {:?}",
                    log_module_context!(),
                    remove.address
                );
                self.remove_listener(remove)
            }
            RequestType::SoftStop(_) => {
                debug!(
                    "{} {} processing soft shutdown",
                    log_module_context!(),
                    request_id
                );
                match self.soft_stop() {
                    Ok(_) => {
                        info!(
                            "{} {} soft stop successful",
                            log_module_context!(),
                            request_id
                        );
                        return WorkerResponse::processing(request.id);
                    }
                    Err(e) => Err(e),
                }
            }
            RequestType::HardStop(_) => {
                debug!(
                    "{} {} processing hard shutdown",
                    log_module_context!(),
                    request_id
                );
                match self.hard_stop() {
                    Ok(_) => {
                        debug!(
                            "{} {} hard stop successful",
                            log_module_context!(),
                            request_id
                        );
                        return WorkerResponse::processing(request.id);
                    }
                    Err(e) => Err(e),
                }
            }
            RequestType::Status(_) => {
                debug!("{} {} status", log_module_context!(), request_id);
                Ok(None)
            }
            RequestType::QueryCertificatesFromWorkers(filters) => {
                if let Some(domain) = filters.domain {
                    debug!(
                        "{} {} query certificate for domain_bytes={}",
                        log_module_context!(),
                        request_id,
                        domain.len(),
                    );
                    self.query_certificate_for_domain(domain)
                } else {
                    debug!(
                        "{} {} query all certificates",
                        log_module_context!(),
                        request_id
                    );
                    self.query_all_certificates()
                }
            }
            other_request => {
                debug!(
                    "{} {} unsupported message for HTTPS proxy, ignoring {:?}",
                    log_module_context!(),
                    request.id,
                    other_request
                );
                Err(ProxyError::UnsupportedMessage)
            }
        };

        match content_result {
            Ok(content) => {
                debug!("{} {} successful", log_module_context!(), request_id);
                match content {
                    Some(content) => WorkerResponse::ok_with_content(request_id, content),
                    None => WorkerResponse::ok(request_id),
                }
            }
            Err(proxy_error) => {
                debug!(
                    "{} {} unsuccessful: {}",
                    log_module_context!(),
                    request_id,
                    proxy_error
                );
                WorkerResponse::error(request_id, proxy_error)
            }
        }
    }
}
impl L7Proxy for HttpsProxy {
    fn kind(&self) -> ListenerType {
        ListenerType::Https
    }

    fn register_socket(
        &self,
        socket: &mut MioTcpStream,
        token: Token,
        interest: Interest,
    ) -> Result<(), std::io::Error> {
        self.registry.register(socket, token, interest)
    }

    fn add_session(&self, session: Rc<RefCell<dyn ProxySession>>) -> Token {
        let mut session_manager = self.sessions.borrow_mut();
        let entry = session_manager.slab.vacant_entry();
        let token = Token(entry.key());
        let _entry = entry.insert(session);
        token
    }

    fn remove_session(&self, token: Token) -> bool {
        let mut sessions = self.sessions.borrow_mut();
        // Mirror of HttpProxy::remove_session — drain the per-(cluster,
        // source-IP) accounting before the slab slot is reused.
        sessions.untrack_all_cluster_ip(token);
        sessions.slab.try_remove(token.0).is_some()
    }

    fn clusters(&self) -> &HashMap<ClusterId, Cluster> {
        &self.clusters
    }

    fn sessions(&self) -> Rc<RefCell<SessionManager>> {
        self.sessions.clone()
    }
}

/// Used for metrics keeping
fn rustls_version_str(version: ProtocolVersion) -> &'static str {
    match version {
        ProtocolVersion::SSLv2 => "tls.version.SSLv2",
        ProtocolVersion::SSLv3 => "tls.version.SSLv3",
        ProtocolVersion::TLSv1_0 => "tls.version.TLSv1_0",
        ProtocolVersion::TLSv1_1 => "tls.version.TLSv1_1",
        ProtocolVersion::TLSv1_2 => "tls.version.TLSv1_2",
        ProtocolVersion::TLSv1_3 => "tls.version.TLSv1_3",
        ProtocolVersion::DTLSv1_0 => "tls.version.DTLSv1_0",
        ProtocolVersion::DTLSv1_2 => "tls.version.DTLSv1_2",
        ProtocolVersion::DTLSv1_3 => "tls.version.DTLSv1_3",
        ProtocolVersion::Unknown(_) => "tls.version.Unknown",
        _ => "tls.version.unimplemented",
    }
}

/// Short label suitable for access logs (e.g. `"TLSv1.3"`).
///
/// Distinct from [`rustls_version_str`] which prefixes with `tls.version.`
/// for metric ingestion. Returns `None` for variants Sōzu does not know how
/// to label, so the access log records `tls_version` as absent rather than
/// emitting a misleading `"unimplemented"` literal.
pub(crate) fn rustls_version_label(version: ProtocolVersion) -> Option<&'static str> {
    match version {
        ProtocolVersion::SSLv2 => Some("SSLv2"),
        ProtocolVersion::SSLv3 => Some("SSLv3"),
        ProtocolVersion::TLSv1_0 => Some("TLSv1.0"),
        ProtocolVersion::TLSv1_1 => Some("TLSv1.1"),
        ProtocolVersion::TLSv1_2 => Some("TLSv1.2"),
        ProtocolVersion::TLSv1_3 => Some("TLSv1.3"),
        ProtocolVersion::DTLSv1_0 => Some("DTLSv1.0"),
        ProtocolVersion::DTLSv1_2 => Some("DTLSv1.2"),
        ProtocolVersion::DTLSv1_3 => Some("DTLSv1.3"),
        _ => None,
    }
}

/// Used for metrics keeping
fn rustls_ciphersuite_str(cipher: SupportedCipherSuite) -> &'static str {
    match cipher.suite() {
        CipherSuite::TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 => {
            "tls.cipher.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256"
        }
        CipherSuite::TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 => {
            "tls.cipher.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256"
        }
        CipherSuite::TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 => {
            "tls.cipher.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256"
        }
        CipherSuite::TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 => {
            "tls.cipher.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384"
        }
        CipherSuite::TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 => {
            "tls.cipher.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256"
        }
        CipherSuite::TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 => {
            "tls.cipher.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384"
        }
        CipherSuite::TLS13_CHACHA20_POLY1305_SHA256 => "tls.cipher.TLS13_CHACHA20_POLY1305_SHA256",
        CipherSuite::TLS13_AES_256_GCM_SHA384 => "tls.cipher.TLS13_AES_256_GCM_SHA384",
        CipherSuite::TLS13_AES_128_GCM_SHA256 => "tls.cipher.TLS13_AES_128_GCM_SHA256",
        _ => "tls.cipher.Unsupported",
    }
}

/// Short label suitable for access logs (e.g. `"TLS_AES_128_GCM_SHA256"`).
///
/// Distinct from [`rustls_ciphersuite_str`] which prefixes with `tls.cipher.`
/// for metric ingestion. Returns `None` for cipher suites Sōzu does not know
/// how to label, so the access log records `tls_cipher` as absent rather
/// than emitting a misleading `"Unsupported"` literal.
pub(crate) fn rustls_ciphersuite_label(cipher: SupportedCipherSuite) -> Option<&'static str> {
    match cipher.suite() {
        CipherSuite::TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 => {
            Some("TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256")
        }
        CipherSuite::TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 => {
            Some("TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256")
        }
        CipherSuite::TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 => {
            Some("TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256")
        }
        CipherSuite::TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 => {
            Some("TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384")
        }
        CipherSuite::TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 => {
            Some("TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256")
        }
        CipherSuite::TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 => {
            Some("TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384")
        }
        CipherSuite::TLS13_CHACHA20_POLY1305_SHA256 => Some("TLS13_CHACHA20_POLY1305_SHA256"),
        CipherSuite::TLS13_AES_256_GCM_SHA384 => Some("TLS13_AES_256_GCM_SHA384"),
        CipherSuite::TLS13_AES_128_GCM_SHA256 => Some("TLS13_AES_128_GCM_SHA256"),
        _ => None,
    }
}

pub mod testing {
    use crate::testing::*;

    /// this function is not used, but is available for example and testing purposes
    pub fn start_https_worker(
        config: HttpsListenerConfig,
        channel: ProxyChannel,
        max_buffers: usize,
        buffer_size: usize,
    ) -> anyhow::Result<()> {
        let address = config.address.into();

        let ServerParts {
            event_loop,
            registry,
            sessions,
            pool,
            backends,
            client_scm_socket: _,
            server_scm_socket,
            server_config,
        } = prebuild_server(max_buffers, buffer_size, true)?;

        let token = {
            let mut sessions = sessions.borrow_mut();
            let entry = sessions.slab.vacant_entry();
            let key = entry.key();
            let _ = entry.insert(Rc::new(RefCell::new(ListenSession {
                protocol: Protocol::HTTPSListen,
            })));
            Token(key)
        };

        let mut proxy = HttpsProxy::new(registry, sessions.clone(), pool.clone(), backends.clone());
        proxy
            .add_listener(config, token)
            .with_context(|| "Failed at creating adding the listener")?;
        proxy
            .activate_listener(&address, None)
            .with_context(|| "Failed at creating activating the listener")?;

        let mut server = Server::new(
            event_loop,
            channel,
            server_scm_socket,
            sessions,
            pool,
            backends,
            None,
            Some(proxy),
            None,
            server_config,
            None,
            false,
        )
        .with_context(|| "Failed at creating server")?;

        debug!("{} starting event loop", log_module_context!());
        server.run();
        debug!("{} ending event loop", log_module_context!());
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use std::sync::Arc;

    use sozu_command::{
        config::ListenerBuilder,
        proto::command::{CertificateAndKey, SocketAddress},
    };

    use super::*;
    use crate::{
        router::{MethodRule, PathRule, Route, Router, pattern_trie::TrieNode},
        socket::SocketHandler,
    };

    /// A handshake whose last `recv` proved the socket empty hands over no
    /// READABLE: the upgraded mux must not `recv` for an EAGAIN (#1609).
    /// READABLE survives when the handshake still had it, or when rustls
    /// holds decrypted input; WRITABLE always does.
    #[test]
    fn the_upgraded_frontend_reads_only_when_a_read_is_due() {
        assert_eq!(
            upgraded_frontend_events(Ready::EMPTY, false),
            Ready::WRITABLE,
            "a drained socket and an empty rustls need no read"
        );
        assert_eq!(
            upgraded_frontend_events(Ready::WRITABLE, false),
            Ready::WRITABLE
        );
        assert_eq!(
            upgraded_frontend_events(Ready::READABLE, false),
            Ready::READABLE | Ready::WRITABLE,
            "an edge not yet read must survive the upgrade"
        );
        assert_eq!(
            upgraded_frontend_events(Ready::EMPTY, true),
            Ready::READABLE | Ready::WRITABLE,
            "plaintext rustls already holds raises no edge"
        );
        assert_eq!(
            upgraded_frontend_events(Ready::READABLE | Ready::HUP, true),
            Ready::READABLE | Ready::WRITABLE | Ready::HUP,
            "a half-close seen during the handshake must reach the mux"
        );
        assert_eq!(
            upgraded_frontend_events(Ready::HUP, false),
            Ready::WRITABLE | Ready::HUP,
            "HUP survives even when no read is due"
        );
        assert_eq!(
            upgraded_frontend_events(Ready::READABLE | Ready::HUP | Ready::WRITE_CLOSED, true),
            Ready::READABLE | Ready::WRITABLE | Ready::HUP | Ready::WRITE_CLOSED,
            "a hang-up seen during the handshake must reach the mux as one"
        );
    }

    #[test]
    fn successful_tls_handshake_log_bounds_sni_and_alpn() {
        const SNI_SECRET: &str = "HTTPS_HANDSHAKE_SNI_SECRET_SENTINEL";
        const ALPN_SECRET: &str = "HTTPS_HANDSHAKE_ALPN_SECRET_SENTINEL";

        let sni = format!("{SNI_SECRET}{}", "x".repeat(4096));
        let alpn = format!("{ALPN_SECRET}{}", "x".repeat(4096));
        let sni_len = sni.len();
        let alpn_len = alpn.len();
        let output = successful_tls_handshake_summary(Some(&sni), Some(&alpn));

        for secret in [SNI_SECRET, ALPN_SECRET] {
            assert!(
                !output.contains(secret),
                "successful TLS handshake log leaked {secret}: {output}"
            );
        }
        for metadata in [
            format!("sni_bytes=Some({sni_len})"),
            format!("alpn_bytes=Some({alpn_len})"),
        ] {
            assert!(
                output.contains(&metadata),
                "successful TLS handshake log omitted {metadata}: {output}"
            );
        }
        assert!(
            output.len() <= 512,
            "successful TLS handshake log is not bounded: {} bytes",
            output.len()
        );
    }

    fn proxy_with_certificate_domain(domain: String) -> HttpsProxy {
        let crate::testing::ServerParts {
            registry,
            sessions,
            pool,
            backends,
            ..
        } = crate::testing::prebuild_server(16, 16_384, false)
            .expect("test HTTPS proxy dependencies must initialize");
        let address = SocketAddress::new_v4(127, 0, 0, 1, crate::testing::provide_port());
        let mut config = ListenerBuilder::new_https(address)
            .to_tls(None)
            .expect("test HTTPS listener config must build");
        config.cipher_list = vec!["TLS13_AES_256_GCM_SHA384".to_owned()];
        config.groups_list = vec!["P-256".to_owned()];
        let mut proxy = HttpsProxy::new(registry, sessions, pool, backends);
        proxy
            .add_listener(config, Token(10))
            .expect("test HTTPS listener must be added");
        proxy
            .add_certificate(AddCertificate {
                address,
                certificate: CertificateAndKey {
                    certificate: include_str!("../assets/certificate.pem").to_owned(),
                    key: include_str!("../assets/key.pem").to_owned(),
                    certificate_chain: Vec::new(),
                    versions: Vec::new(),
                    names: vec![domain],
                },
                expired_at: None,
            })
            .expect("test certificate must be added");
        proxy
    }

    /// The two `query_*` paths take the resolver mutex with `unwrap_msg!`,
    /// while every `add`/`remove`/`replace` sibling takes it with
    /// `.lock().map_err(|e| ProxyError::Lock(e.to_string()))?`
    /// (https.rs `add_certificate`/`remove_certificate`/`replace_certificate`).
    /// That asymmetry is the finding: a poisoned resolver — any earlier panic
    /// while the lock was held — turns a read-only `QueryCertificates`
    /// control-plane request into a worker kill instead of an error response.
    ///
    /// To SEE THIS RED: put `unwrap_msg!(owned.resolver.0.lock())` back in
    /// `query_all_certificates` and `query_certificate_for_domain` (restoring
    /// the `util::UnwrapLog` import the removal made unused) — both calls
    /// below then panic with `PoisonError` instead of returning
    /// `ProxyError::Lock`.
    #[test]
    fn a_poisoned_resolver_fails_the_certificate_queries_instead_of_the_worker() {
        let mut proxy = proxy_with_certificate_domain("lolcatho.st".to_owned());

        let resolver = proxy
            .listeners
            .values()
            .next()
            .expect("the test proxy has one listener")
            .borrow()
            .resolver()
            .clone();

        // Poison the mutex exactly as a panic inside the worker would: hold
        // the guard, unwind. `join` swallows the unwind so the test process
        // survives to observe the poisoned state.
        let poisoner = resolver.clone();
        let unwound = std::thread::spawn(move || {
            let _guard = poisoner.0.lock().expect("first lock is not poisoned");
            panic!("simulated worker panic while holding the resolver lock");
        })
        .join();
        assert!(unwound.is_err(), "the poisoning thread must have unwound");
        assert!(
            resolver.0.lock().is_err(),
            "the resolver mutex must now be poisoned"
        );

        assert!(
            matches!(proxy.query_all_certificates(), Err(ProxyError::Lock(_))),
            "Certificates::All on a poisoned resolver must report a lock error"
        );
        assert!(
            matches!(
                proxy.query_certificate_for_domain("lolcatho.st".to_owned()),
                Err(ProxyError::Lock(_))
            ),
            "Certificates::Domain on a poisoned resolver must report a lock error"
        );
    }

    /// `String::from_utf8(trie_key).unwrap()` in `query_all_certificates` is a
    /// second unconditional panic on a value the function does not own. The
    /// control plane cannot currently reach it — `AddCertificate.names` is
    /// `Vec<String>` and `tls.rs::add_certificate` inserts
    /// `String::into_bytes()`, while `TrieNode::to_hashmap` clones the stored
    /// key back verbatim — so this is an invariant, and the red below is BY
    /// MUTATION of the trie: `TrieNode<Fingerprint>` is `pub` and its key type
    /// is `Vec<u8>`, so the type permits what the control plane does not. A
    /// certificate listing must not be able to kill the worker over a key it
    /// merely echoes.
    ///
    /// To SEE THIS RED: put `String::from_utf8(k).unwrap()` back in
    /// `query_all_certificates` — this test then panics with
    /// `FromUtf8Error`.
    #[test]
    fn a_non_utf8_resolver_key_is_listed_lossily_not_panicked() {
        let mut proxy = proxy_with_certificate_domain("lolcatho.st".to_owned());

        let resolver = proxy
            .listeners
            .values()
            .next()
            .expect("the test proxy has one listener")
            .borrow()
            .resolver()
            .clone();
        {
            let mut owned = resolver.0.lock().expect("resolver lock");
            let inserted = owned
                .domains
                .insert(vec![0xff, 0xfe], Fingerprint(vec![0x01, 0x02]));
            assert_ne!(
                inserted,
                crate::router::pattern_trie::InsertResult::Failed,
                "the SNI trie must accept the non-UTF-8 key this test relies on"
            );
        }

        let response = proxy
            .query_all_certificates()
            .expect("a non-UTF-8 trie key must not fail the query");
        assert!(
            response.is_some(),
            "Certificates::All must still answer with a listing"
        );
    }

    #[test]
    fn query_all_certificates_log_redacts_response_domains() {
        const DOMAIN_SECRET: &str = "QUERY_ALL_CERTIFICATE_DOMAIN_SECRET_SENTINEL";

        // Below `router::MAX_HOSTNAME_LENGTH` so the certificate passes
        // add-time name validation; the redaction property under test is
        // length-independent.
        let domain = format!("{DOMAIN_SECRET}{}", "x".repeat(2048));
        let output = crate::capture_test_logs(move || {
            let mut proxy = proxy_with_certificate_domain(domain);
            proxy
                .query_all_certificates()
                .expect("certificate query must succeed");
        });

        assert!(
            !output.contains(DOMAIN_SECRET),
            "Certificates::All log leaked response domain {DOMAIN_SECRET}"
        );
        for metadata in ["listeners_count=1", "certificates_count=1"] {
            assert!(
                output.contains(metadata),
                "Certificates::All log omitted bounded metadata {metadata}: {output}"
            );
        }
        assert!(
            output.len() <= 1024,
            "Certificates::All log capture is not bounded: {} bytes",
            output.len()
        );
    }

    #[test]
    fn query_certificate_for_domain_log_redacts_request_and_response_domain() {
        const DOMAIN_SECRET: &str = "QUERY_ONE_CERTIFICATE_DOMAIN_SECRET_SENTINEL";

        // Below `router::MAX_HOSTNAME_LENGTH` -- see
        // `query_all_certificates_log_redacts_response_domains`.
        let domain = format!("{DOMAIN_SECRET}{}", "x".repeat(2048));
        let domain_len = domain.len();
        let output = crate::capture_test_logs_at_level("debug", move || {
            let mut proxy = proxy_with_certificate_domain(domain.clone());
            let response = proxy.notify(WorkerRequest {
                id: "query-domain-redaction-test".to_owned(),
                content: RequestType::QueryCertificatesFromWorkers(
                    sozu_command::proto::command::QueryCertificatesFilters {
                        domain: Some(domain),
                        fingerprint: None,
                    },
                )
                .into(),
            });
            assert_eq!(
                response.status,
                sozu_command::proto::command::ResponseStatus::Ok as i32,
                "domain certificate query must succeed: {}",
                response.message
            );
        });

        assert!(
            !output.contains(DOMAIN_SECRET),
            "Certificates::Domain log leaked request or response domain {DOMAIN_SECRET}"
        );
        for metadata in [
            format!("domain_bytes={domain_len}"),
            "listeners_count=1".to_owned(),
            "certificates_count=1".to_owned(),
        ] {
            assert!(
                output.contains(&metadata),
                "Certificates::Domain log omitted bounded metadata {metadata}: {output}"
            );
        }
        assert!(
            output.len() <= 1024,
            "Certificates::Domain log capture is not bounded: {} bytes",
            output.len()
        );
    }

    #[test]
    fn frontend_from_request_test() {
        let cluster_id1 = ClusterId::from("cluster_1");
        let cluster_id2 = ClusterId::from("cluster_2");
        let cluster_id3 = ClusterId::from("cluster_3");
        let uri1 = "/".to_owned();
        let uri2 = "/yolo".to_owned();
        let uri3 = "/yolo/swag".to_owned();

        let mut fronts = Router::new();
        assert!(fronts.add_tree_rule(
            "lolcatho.st".as_bytes(),
            &PathRule::Prefix(uri1),
            &MethodRule::new(None),
            &Route::ClusterId(cluster_id1.clone())
        ));
        assert!(fronts.add_tree_rule(
            "lolcatho.st".as_bytes(),
            &PathRule::Prefix(uri2),
            &MethodRule::new(None),
            &Route::ClusterId(cluster_id2)
        ));
        assert!(fronts.add_tree_rule(
            "lolcatho.st".as_bytes(),
            &PathRule::Prefix(uri3),
            &MethodRule::new(None),
            &Route::ClusterId(cluster_id3)
        ));
        assert!(fronts.add_tree_rule(
            "other.domain".as_bytes(),
            &PathRule::Prefix("test".to_string()),
            &MethodRule::new(None),
            &Route::ClusterId(cluster_id1)
        ));

        let address = SocketAddress::new_v4(127, 0, 0, 1, 1032);
        let resolver = Arc::new(MutexCertificateResolver::default());

        let crypto_provider = Arc::new(default_provider());

        let server_config = RustlsServerConfig::builder_with_provider(crypto_provider)
            .with_protocol_versions(&[&rustls::version::TLS12, &rustls::version::TLS13])
            .expect("could not create rustls config server")
            .with_no_client_auth()
            .with_cert_resolver(resolver.clone());

        let rustls_details = Arc::new(server_config);

        let default_config = ListenerBuilder::new_https(address)
            .to_tls(None)
            .expect("Could not create default HTTPS listener config");

        println!("it doesn't even matter");

        let listener = HttpsListener {
            parked_listener: None,
            nodelay_backlog: false,
            listener: None,
            address: address.into(),
            fronts,
            rustls_details,
            resolver,
            answers: Rc::new(RefCell::new(
                HttpAnswers::new(&std::collections::BTreeMap::new()).unwrap(),
            )),
            config: default_config,
            token: Token(0),
            active: true,
            tags: BTreeMap::new(),
        };

        println!("TEST {}", line!());
        let frontend1 = listener.frontend_from_request("lolcatho.st", "/", &Method::Get);
        assert_eq!(
            frontend1
                .expect("should find a frontend")
                .cluster_id
                .as_deref(),
            Some("cluster_1")
        );
        println!("TEST {}", line!());
        let frontend2 = listener.frontend_from_request("lolcatho.st", "/test", &Method::Get);
        assert_eq!(
            frontend2
                .expect("should find a frontend")
                .cluster_id
                .as_deref(),
            Some("cluster_1")
        );
        println!("TEST {}", line!());
        let frontend3 = listener.frontend_from_request("lolcatho.st", "/yolo/test", &Method::Get);
        assert_eq!(
            frontend3
                .expect("should find a frontend")
                .cluster_id
                .as_deref(),
            Some("cluster_2")
        );
        println!("TEST {}", line!());
        let frontend4 = listener.frontend_from_request("lolcatho.st", "/yolo/swag", &Method::Get);
        assert_eq!(
            frontend4
                .expect("should find a frontend")
                .cluster_id
                .as_deref(),
            Some("cluster_3")
        );
        println!("TEST {}", line!());
        let frontend5 = listener.frontend_from_request("domain", "/", &Method::Get);
        assert!(frontend5.is_err());
        // assert!(false);
    }

    #[test]
    fn wildcard_certificate_names() {
        let mut trie = TrieNode::root();

        trie.domain_insert("*.services.clever-cloud.com".as_bytes().to_vec(), 1u8);
        trie.domain_insert("*.clever-cloud.com".as_bytes().to_vec(), 2u8);
        trie.domain_insert("services.clever-cloud.com".as_bytes().to_vec(), 0u8);
        trie.domain_insert(
            "abprefix.services.clever-cloud.com".as_bytes().to_vec(),
            3u8,
        );
        trie.domain_insert(
            "cdprefix.services.clever-cloud.com".as_bytes().to_vec(),
            4u8,
        );

        let res = trie.domain_lookup(b"test.services.clever-cloud.com", true);
        println!("query result: {res:?}");

        assert_eq!(
            trie.domain_lookup(b"pgstudio.services.clever-cloud.com", true),
            Some(&("*.services.clever-cloud.com".as_bytes().to_vec(), 1u8))
        );
        assert_eq!(
            trie.domain_lookup(b"test-prefix.services.clever-cloud.com", true),
            Some(&("*.services.clever-cloud.com".as_bytes().to_vec(), 1u8))
        );
    }

    #[test]
    fn wildcard_with_subdomains() {
        let mut trie = TrieNode::root();

        trie.domain_insert("*.test.example.com".as_bytes().to_vec(), 1u8);
        trie.domain_insert("hello.sub.test.example.com".as_bytes().to_vec(), 2u8);

        let res = trie.domain_lookup(b"sub.test.example.com", true);
        println!("query result: {res:?}");

        assert_eq!(
            trie.domain_lookup(b"sub.test.example.com", true),
            Some(&("*.test.example.com".as_bytes().to_vec(), 1u8))
        );
        assert_eq!(
            trie.domain_lookup(b"hello.sub.test.example.com", true),
            Some(&("hello.sub.test.example.com".as_bytes().to_vec(), 2u8))
        );

        // now try in a different order
        let mut trie = TrieNode::root();

        trie.domain_insert("hello.sub.test.example.com".as_bytes().to_vec(), 2u8);
        trie.domain_insert("*.test.example.com".as_bytes().to_vec(), 1u8);

        let res = trie.domain_lookup(b"sub.test.example.com", true);
        println!("query result: {res:?}");

        assert_eq!(
            trie.domain_lookup(b"sub.test.example.com", true),
            Some(&("*.test.example.com".as_bytes().to_vec(), 1u8))
        );
        assert_eq!(
            trie.domain_lookup(b"hello.sub.test.example.com", true),
            Some(&("hello.sub.test.example.com".as_bytes().to_vec(), 2u8))
        );
    }

    /// sozu#322: the HTTPS twin of `lib/src/http.rs`'s
    /// `a_listener_with_an_unknown_forwarded_headers_value_is_refused`.
    #[test]
    fn a_listener_with_an_unknown_forwarded_headers_value_is_refused() {
        let build = |forwarded_headers: Option<i32>| {
            let mut cfg = ListenerBuilder::new_https(SocketAddress::new_v4(127, 0, 0, 1, 1043))
                .to_tls(None)
                .expect("default HTTPS listener config");
            cfg.forwarded_headers = forwarded_headers;
            HttpsListener::try_new(cfg, Token(0))
        };
        assert!(build(Some(-1)).is_err(), "an unknown mode must be refused");
        let listener = build(Some(ForwardedHeaders::None as i32)).expect("a known mode");
        assert_eq!(listener.get_forwarded_headers(), ForwardedHeaders::None);
    }

    /// The HTTPS twin of `lib/src/http.rs`'s
    /// `get_h2_flood_config_maps_every_listener_knob_to_its_own_threshold`
    /// (sozu-proxy/sozu#1418): the same thirteen positional arguments are
    /// spelled out a second time here, so the two copies need the same
    /// transposition guard. Every value is distinct.
    #[test]
    fn get_h2_flood_config_maps_every_listener_knob_to_its_own_threshold() {
        let mut cfg = ListenerBuilder::new_https(SocketAddress::new_v4(127, 0, 0, 1, 1042))
            .to_tls(None)
            .expect("default HTTPS listener config");
        cfg.h2_max_rst_stream_per_window = Some(101);
        cfg.h2_max_ping_per_window = Some(102);
        cfg.h2_max_settings_per_window = Some(103);
        cfg.h2_max_empty_data_per_window = Some(104);
        cfg.h2_max_window_update_stream0_per_window = Some(105);
        cfg.h2_max_continuation_frames = Some(106);
        cfg.h2_max_glitch_count = Some(107);
        cfg.h2_max_rst_stream_lifetime = Some(108);
        cfg.h2_max_rst_stream_abusive_lifetime = Some(109);
        cfg.h2_max_rst_stream_emitted_lifetime = Some(110);
        cfg.h2_max_header_list_size = Some(111);
        cfg.h2_max_header_table_size = Some(112);
        cfg.h2_max_header_fields = Some(113);
        cfg.h2_stream_refusal_percent = Some(114);

        let listener = HttpsListener::try_new(cfg, Token(0)).expect("build listener");
        let flood = listener.get_h2_flood_config();

        assert_eq!(flood.max_rst_stream_per_window(), 101);
        assert_eq!(flood.max_ping_per_window(), 102);
        assert_eq!(flood.max_settings_per_window(), 103);
        assert_eq!(flood.max_empty_data_per_window(), 104);
        assert_eq!(flood.max_window_update_stream0_per_window(), 105);
        assert_eq!(flood.max_continuation_frames(), 106);
        assert_eq!(flood.max_glitch_count(), 107);
        assert_eq!(flood.max_rst_stream_lifetime(), 108);
        assert_eq!(flood.max_rst_stream_abusive_lifetime(), 109);
        assert_eq!(flood.max_rst_stream_emitted_lifetime(), 110);
        assert_eq!(flood.max_header_list_size(), 111);
        assert_eq!(flood.max_header_table_size(), 112);
        assert_eq!(flood.max_header_fields(), 113);
        assert_eq!(flood.stream_refusal_percent(), 114);
    }

    #[test]
    fn h2_stream_idle_timeout_inherits_back_timeout() {
        use std::time::Duration;

        let address = SocketAddress::new_v4(127, 0, 0, 1, 1041);
        let build = |back_timeout: u32, explicit: Option<u32>| -> HttpsListener {
            let mut cfg = ListenerBuilder::new_https(address)
                .to_tls(None)
                .expect("default HTTPS listener config");
            cfg.back_timeout = back_timeout;
            cfg.h2_stream_idle_timeout_seconds = explicit;
            HttpsListener::try_new(cfg, Token(0)).expect("build listener")
        };

        // Knob unset: inherit back_timeout when it exceeds the 30s floor.
        assert_eq!(
            build(180, None).get_h2_stream_idle_timeout(),
            Duration::from_secs(180)
        );

        // Knob unset, back_timeout below floor: stay at 30s.
        assert_eq!(
            build(5, None).get_h2_stream_idle_timeout(),
            Duration::from_secs(30)
        );

        // Explicit values win in both directions.
        assert_eq!(
            build(180, Some(10)).get_h2_stream_idle_timeout(),
            Duration::from_secs(10)
        );
        assert_eq!(
            build(5, Some(600)).get_h2_stream_idle_timeout(),
            Duration::from_secs(600)
        );

        // `Some(0)` is clamped to 1s.
        assert_eq!(
            build(180, Some(0)).get_h2_stream_idle_timeout(),
            Duration::from_secs(1)
        );
    }

    // ── FrontRustls peer snapshot (the PROXY-protocol seeding decision) ──

    /// Source address a PROXY v2 header advertises. Non-loopback so it can
    /// never collide with the address of the connection the test really opens.
    const PROXY_ADVERTISED_PEER: &str = "10.0.0.42:12345";

    /// The peer snapshot handed to [`FrontRustls`] is the session's known peer
    /// address — on an expect-proxy frontend, the source the PROXY header
    /// advertised — and NOT `getpeername(2)` on the accepted socket, which on
    /// such a frontend is the load balancer.
    ///
    /// This is the one substitution a future editor is most likely to make
    /// here. Hoisting `let raw_peer = handshake.stream.peer_addr().ok();` above
    /// the struct literal and seeding from that compiles, passes every other
    /// test in this file, and silently restores the split this change exists to
    /// remove: the `HTTPS` line naming the client while the `MUX-*` lines name
    /// the load balancer, for one and the same request id.
    ///
    /// The test drives the real `upgrade_handshake`, so it pins the seeding
    /// site rather than the accessor. `session.peer_address` is set the way
    /// `upgrade_expect` sets it (https.rs, `self.peer_address =
    /// Some(session_address)` on the PROXY-header branch) instead of feeding a
    /// real PROXY header — that adoption already has its own `debug_assert_eq!`
    /// in `upgrade_expect` and its own e2e coverage; what is unguarded, and
    /// what this test guards, is the hand-off from there into the socket
    /// handler. `handshake.peer_address` is set to the same value because
    /// `upgrade_expect` passes `self.peer_address` straight into
    /// `TlsHandshake::new`: in production the two are always equal, so the test
    /// must not be able to pass or fail on the difference between them.
    ///
    /// To SEE THIS RED: in `upgrade_handshake`, put
    /// `let raw_peer = handshake.stream.peer_addr().ok();` before the
    /// `FrontRustls` literal and replace `configured_peer: self.peer_address,`
    /// with `configured_peer: raw_peer,`. (Reading `handshake.stream` inside
    /// the literal itself does not compile — the `stream:` field has already
    /// moved it — which is the only reason the mutation needs the hoist.)
    #[test]
    fn front_rustls_peer_snapshot_is_the_session_peer_not_the_accepted_socket() {
        let advertised: StdSocketAddr = PROXY_ADVERTISED_PEER
            .parse()
            .expect("the advertised peer literal must parse");

        let proxy = proxy_with_certificate_domain("lolcatho.st".to_owned());
        let listener = proxy
            .listeners
            .values()
            .next()
            .expect("the test proxy has one listener")
            .clone();
        let pool = Rc::downgrade(&proxy.pool);
        let rustls_details = ServerConnection::new(listener.borrow().rustls_details.clone())
            .expect("a test rustls server session must be created");
        let public_address = *listener.borrow().get_addr();
        let proxy = Rc::new(RefCell::new(proxy));

        // A genuinely established loopback connection stands in for the one the
        // load balancer opened. `getpeername(2)` on it answers the balancer's
        // address and keeps answering it — the point being that the snapshot
        // must disagree with a live lookup that is perfectly healthy.
        let balancer = std::net::TcpListener::bind("127.0.0.1:0")
            .expect("test listener must bind to a loopback port");
        let balancer_peer = balancer
            .local_addr()
            .expect("test listener must report its local address");
        let stream =
            std::net::TcpStream::connect(balancer_peer).expect("loopback connect must complete");
        stream
            .set_nonblocking(true)
            .expect("mio requires a nonblocking stream");
        let stream = MioTcpStream::from_std(stream);

        let mut session = HttpsSession::new(
            Duration::from_secs(30),
            Duration::from_secs(30),
            Duration::from_secs(30),
            Duration::from_secs(30),
            // Built on the direct route so the session owns exactly one stream
            // and one rustls session; the PROXY adoption is then applied below.
            false,
            listener,
            pool,
            proxy,
            public_address,
            rustls_details,
            stream,
            // What `accept(2)` reports for this connection: the far end, which
            // for the stand-in is the balancer.
            balancer_peer,
            Token(0),
            Duration::from_secs(0),
        );

        assert_eq!(
            session.peer_address,
            Some(balancer_peer),
            "a direct-route session starts out with the accepted socket's peer"
        );

        let mut handshake = match session.state.take() {
            HttpsStateMachine::Handshake(handshake) => handshake,
            _ => panic!("a non-expect-proxy session must start in the TLS handshake state"),
        };

        // What `upgrade_expect` does once the PROXY header parses.
        session.peer_address = Some(advertised);
        handshake.peer_address = Some(advertised);
        assert_ne!(
            advertised, balancer_peer,
            "the advertised and connection peers must differ for this test to discriminate"
        );

        let upgraded = session
            .upgrade_handshake(handshake)
            .expect("the handshake must upgrade to a mux session");
        // Borrowed rather than moved out: `ConnectionH2` implements `Drop`, so
        // its `socket` field cannot leave the connection.
        let (snapshot, live_lookup) = match &upgraded {
            HttpsStateMachine::Mux(mux) => match &mux.frontend {
                mux::Connection::H1(connection) => (
                    connection.socket.peer_addr(),
                    connection.socket.socket_ref().peer_addr().ok(),
                ),
                mux::Connection::H2(connection) => (
                    connection.socket.peer_addr(),
                    connection.socket.socket_ref().peer_addr().ok(),
                ),
            },
            _ => panic!("a completed TLS handshake must upgrade into the mux state"),
        };

        // Premise: the live lookup is healthy and still reports the balancer,
        // so the assertion below cannot pass for the wrong reason.
        assert_eq!(
            live_lookup,
            Some(balancer_peer),
            "the frontend socket must still be connected to the stand-in balancer"
        );
        assert_eq!(
            snapshot,
            Some(advertised),
            "FrontRustls must carry the PROXY-advertised source, not the accepted socket's peer"
        );
    }

    /// The `or_else` arm of [`FrontRustls::peer_addr`] answers for a handler
    /// built with no peer address. No production route builds one any more:
    /// the direct (non-expect-proxy) route seeds `peer_address` with the
    /// address `accept(2)` returned (sozu-proxy/sozu#1586), and the
    /// expect-proxy route only reaches the handshake with the PROXY-advertised
    /// source. The arm stays as defence in depth — without it a `None` would
    /// blank the `peer=` slot for the whole connection even though the socket
    /// is healthy and the kernel would answer — so the test builds that
    /// handler by hand.
    ///
    /// `SessionTcpStream`'s identical arm has had
    /// `socket::tests::session_tcp_stream_peer_addr_falls_back_to_the_live_lookup`
    /// since it was written; this is the missing twin for `FrontRustls`.
    ///
    /// To SEE THIS RED: in `impl SocketHandler for FrontRustls`, drop the
    /// `.or_else(|| self.stream.peer_addr().ok())` from `peer_addr`. The
    /// handler then answers `None` for a perfectly healthy connection.
    #[test]
    fn front_rustls_peer_addr_falls_back_to_the_live_lookup() {
        let proxy = proxy_with_certificate_domain("lolcatho.st".to_owned());
        let listener = proxy
            .listeners
            .values()
            .next()
            .expect("the test proxy has one listener")
            .clone();
        let pool = Rc::downgrade(&proxy.pool);
        let rustls_details = ServerConnection::new(listener.borrow().rustls_details.clone())
            .expect("a test rustls server session must be created");
        let public_address = *listener.borrow().get_addr();
        let proxy = Rc::new(RefCell::new(proxy));

        let peer = std::net::TcpListener::bind("127.0.0.1:0")
            .expect("test listener must bind to a loopback port");
        let live_peer = peer
            .local_addr()
            .expect("test listener must report its local address");
        let stream =
            std::net::TcpStream::connect(live_peer).expect("loopback connect must complete");
        stream
            .set_nonblocking(true)
            .expect("mio requires a nonblocking stream");
        let stream = MioTcpStream::from_std(stream);

        let mut session = HttpsSession::new(
            Duration::from_secs(30),
            Duration::from_secs(30),
            Duration::from_secs(30),
            Duration::from_secs(30),
            false,
            listener,
            pool,
            proxy,
            public_address,
            rustls_details,
            stream,
            live_peer,
            Token(0),
            Duration::from_secs(0),
        );

        let mut handshake = match session.state.take() {
            HttpsStateMachine::Handshake(handshake) => handshake,
            _ => panic!("a non-expect-proxy session must start in the TLS handshake state"),
        };

        // A session that knows no peer, which the handler must fall back from.
        session.peer_address = None;
        handshake.peer_address = None;

        let upgraded = session
            .upgrade_handshake(handshake)
            .expect("the handshake must upgrade to a mux session");
        let snapshot = match &upgraded {
            HttpsStateMachine::Mux(mux) => match &mux.frontend {
                mux::Connection::H1(connection) => connection.socket.peer_addr(),
                mux::Connection::H2(connection) => connection.socket.peer_addr(),
            },
            _ => panic!("a completed TLS handshake must upgrade into the mux state"),
        };

        assert_eq!(
            snapshot,
            Some(live_peer),
            "with nothing cached, FrontRustls::peer_addr must degrade to getpeername(2)"
        );
    }

    /// `sozu query certificates --domain <d>` must ask the resolver the
    /// same question a TLS handshake asks it.
    ///
    /// The resolver keys its SNI trie on ASCII-lowercased certificate
    /// names (`CertifiedKeyWrapper::try_from`, `lib/src/tls.rs`), because
    /// rustls hands `ResolvesServerCert::resolve` an SNI it has already
    /// lowercased and no other key can ever be looked up at handshake
    /// time. The operator query has to be normalised the same way, or
    /// `sozu query certificates --domain MiXeD.Example.COM` reports the
    /// certificate missing while the proxy is serving it on every
    /// handshake for that name.
    ///
    /// To SEE THIS RED: in `query_certificate_for_domain`, look the
    /// domain up with `domain.as_bytes()` instead of
    /// `domain_key.as_bytes()`. The two case-varying queries return zero
    /// summaries.
    #[test]
    fn query_certificate_for_domain_answers_any_spelling_of_the_name() {
        let mut proxy = proxy_with_certificate_domain("MiXeD.Example.COM".to_owned());

        let mut summaries_for = |query: &str| {
            let response = proxy
                .query_certificate_for_domain(query.to_owned())
                .expect("the domain certificate query must succeed")
                .expect("the domain certificate query must return content");
            match response.content_type {
                Some(ContentType::CertificatesByAddress(list)) => list
                    .certificates
                    .iter()
                    .map(|entry| entry.certificate_summaries.len())
                    .sum::<usize>(),
                _ => panic!("the domain query must answer with CertificatesByAddress"),
            }
        };

        for query in [
            "MiXeD.Example.COM",
            "mixed.example.com",
            "MIXED.EXAMPLE.COM",
        ] {
            assert_eq!(
                summaries_for(query),
                1,
                "querying {query:?} must find the certificate stored as MiXeD.Example.COM",
            );
        }

        assert_eq!(
            summaries_for("other.example.com"),
            0,
            "normalising the query must not make an unrelated domain match",
        );
    }

    /// An HTTPS session upgraded to the mux over a live loopback connection,
    /// with the accepted peer standing in for the client. The TLS handshake
    /// never ran; nothing here reads what the client receives beyond the FIN.
    fn https_mux_session_with_peer() -> (HttpsSession, std::net::TcpStream) {
        let proxy = proxy_with_certificate_domain("lolcatho.st".to_owned());
        let listener = proxy
            .listeners
            .values()
            .next()
            .expect("the test proxy has one listener")
            .clone();
        let pool = Rc::downgrade(&proxy.pool);
        let rustls_details = ServerConnection::new(listener.borrow().rustls_details.clone())
            .expect("a test rustls server session must be created");
        let public_address = *listener.borrow().get_addr();
        let proxy = Rc::new(RefCell::new(proxy));

        let accepting = std::net::TcpListener::bind("127.0.0.1:0")
            .expect("test listener must bind to a loopback port");
        let address = accepting
            .local_addr()
            .expect("test listener must report its local address");
        let stream = std::net::TcpStream::connect(address).expect("loopback connect must complete");
        let (client, client_address) = accepting.accept().expect("loopback accept must complete");
        client
            .set_nonblocking(true)
            .expect("the client stand-in must be nonblocking");
        stream
            .set_nonblocking(true)
            .expect("mio requires a nonblocking stream");

        let mut session = HttpsSession::new(
            Duration::from_secs(30),
            Duration::from_secs(30),
            Duration::from_secs(30),
            Duration::from_secs(30),
            false,
            listener,
            pool,
            proxy,
            public_address,
            rustls_details,
            MioTcpStream::from_std(stream),
            client_address,
            Token(0),
            Duration::from_secs(0),
        );
        let handshake = match session.state.take() {
            HttpsStateMachine::Handshake(handshake) => handshake,
            _ => panic!("a non-expect-proxy session must start in the TLS handshake state"),
        };
        session.state = session
            .upgrade_handshake(handshake)
            .expect("the handshake must upgrade to a mux session");
        (session, client)
    }

    /// Close `session`, drop it as the event loop does, and return the
    /// `shutdown(SHUT_WR)` calls the close issued and whether `client` then
    /// observed the FIN.
    fn frontend_shutdowns_of_a_close(
        mut session: HttpsSession,
        client: &mut std::net::TcpStream,
    ) -> (usize, bool) {
        use std::io::Read;

        let before = mux::shutdown_writes();
        session.close();
        let shutdowns = mux::shutdown_writes() - before;
        drop(session);

        let deadline = Instant::now() + Duration::from_secs(2);
        let mut chunk = [0u8; 4096];
        let saw_fin = loop {
            match client.read(&mut chunk) {
                Ok(0) => break true,
                Ok(_) => {}
                Err(e) if e.kind() == ErrorKind::WouldBlock && Instant::now() < deadline => {
                    std::thread::sleep(Duration::from_millis(5));
                }
                Err(_) => break false,
            }
        };
        (shutdowns, saw_fin)
    }

    /// Issue #1603: once the client has closed its side, `HttpsSession::close`
    /// does not `shutdown(SHUT_WR)` the frontend socket — on an H2 client that
    /// had already reset, that call failed with `ENOTCONN` on every
    /// connection. The client, which only half-closed here and is still
    /// reading, gets its FIN from the close alone.
    ///
    /// TO SEE THIS RED: make `mux::shutdown_write` ignore `peer_closed`, or
    /// drop the `peer_disconnected` arm from `HttpsSession::close` (then only
    /// the `read EOF` case fails). The first assertion fails with `left: 1`,
    /// `right: 0`.
    ///
    /// Two ways to know it: the HUP the event loop records for the client's
    /// FIN, and `FrontRustls::peer_disconnected`, set by the read that met the
    /// EOF or the `close_notify` — the H2 case, where the close follows in
    /// the same pass and no epoll event reports it.
    #[test]
    fn https_close_skips_the_frontend_shutdown_once_the_client_closed() {
        for how in ["epoll HUP", "read EOF"] {
            let (mut session, mut client) = https_mux_session_with_peer();
            client
                .shutdown(std::net::Shutdown::Write)
                .expect("the client stand-in must send its FIN");
            let HttpsStateMachine::Mux(mux) = &mut session.state else {
                unreachable!("https_mux_session_with_peer returns a mux session")
            };
            if how == "epoll HUP" {
                mux.frontend.readiness_mut().event.insert(Ready::HUP);
            } else {
                match &mut mux.frontend {
                    mux::Connection::H1(connection) => connection.socket.peer_disconnected = true,
                    mux::Connection::H2(connection) => connection.socket.peer_disconnected = true,
                }
            }

            let (shutdowns, saw_fin) = frontend_shutdowns_of_a_close(session, &mut client);
            assert_eq!(
                shutdowns, 0,
                "a frontend whose client closed ({how}) must not be shut down before its close"
            );
            assert!(
                saw_fin,
                "the close alone must still deliver the FIN to a half-closed client ({how})"
            );
        }
    }

    /// The other half of #1603: a client that is still there keeps the
    /// frontend `shutdown(SHUT_WR)` and observes the FIN.
    #[test]
    fn https_close_keeps_the_frontend_shutdown_while_the_client_is_there() {
        let (session, mut client) = https_mux_session_with_peer();
        let (shutdowns, saw_fin) = frontend_shutdowns_of_a_close(session, &mut client);
        assert_eq!(
            shutdowns, 1,
            "a frontend whose client is still there must keep its shutdown(SHUT_WR)"
        );
        assert!(saw_fin, "the client must observe the FIN");
    }
}

#[cfg(test)]
mod listener_sibling_tests {
    use sozu_command::{
        config::ListenerBuilder,
        proto::command::{
            CertificateAndKey, HstsConfig, PathRule, RequestHttpFrontend, SocketAddress,
        },
    };

    use super::*;
    use crate::testing::{ServerParts, prebuild_server, provide_port};

    fn proxy() -> HttpsProxy {
        let ServerParts {
            registry,
            sessions,
            pool,
            backends,
            ..
        } = prebuild_server(16, 16384, false).expect("could not prebuild a test server");
        HttpsProxy::new(registry, sessions, pool, backends)
    }

    fn add(proxy: &mut HttpsProxy, address: SocketAddress, interface: Option<&str>, token: usize) {
        let config = ListenerBuilder::new_https(address)
            .with_interface(interface)
            .to_tls(None)
            .expect("could not build the listener config");
        proxy
            .add_listener(config, Token(token))
            .expect("could not add the listener");
    }

    fn certificate(address: SocketAddress) -> AddCertificate {
        AddCertificate {
            address,
            certificate: CertificateAndKey {
                certificate: include_str!("../assets/certificate.pem").to_owned(),
                key: include_str!("../assets/key.pem").to_owned(),
                certificate_chain: Vec::new(),
                versions: Vec::new(),
                names: vec!["example.com".to_owned()],
            },
            expired_at: None,
        }
    }

    fn front(address: SocketAddress) -> RequestHttpFrontend {
        RequestHttpFrontend {
            cluster_id: Some("cluster-a".to_owned()),
            address,
            hostname: "example.com".to_owned(),
            path: PathRule::prefix("/".to_owned()),
            ..Default::default()
        }
    }

    fn serves_certificate(proxy: &HttpsProxy, token: usize) -> bool {
        proxy.listeners[&Token(token)]
            .borrow()
            .resolver
            .0
            .lock()
            .expect("resolver lock")
            .domains
            .domain_lookup(b"example.com", true)
            .is_some()
    }

    fn routes(proxy: &HttpsProxy, token: usize) -> bool {
        proxy.listeners[&Token(token)]
            .borrow()
            .fronts
            .lookup("example.com", "/", &Method::Get)
            .is_ok()
    }

    /// An HTTPS listener added on an address that already serves a certificate
    /// and a frontend takes both over from the listener already there, so it
    /// completes TLS handshakes and routes from its first connection
    /// (sozu-proxy/sozu#719). It gets its own copy of the certificates: a
    /// later change reaches it through the fan-out, like its sibling.
    #[test]
    fn a_listener_added_next_to_a_sibling_takes_over_its_certificates_and_frontends() {
        let mut proxy = proxy();
        let address = SocketAddress::new_v4(0, 0, 0, 0, provide_port());
        add(&mut proxy, address, None, 0);
        proxy
            .add_certificate(certificate(address))
            .expect("add the certificate");
        proxy
            .add_https_frontend(front(address))
            .expect("add the frontend");
        add(&mut proxy, address, Some("lo"), 1);

        assert!(serves_certificate(&proxy, 0));
        assert!(
            serves_certificate(&proxy, 1),
            "the listener added after the certificate must serve it too"
        );
        assert!(
            routes(&proxy, 1),
            "the listener added after the frontend must route it too"
        );

        proxy
            .remove_https_frontend(front(address))
            .expect("remove the frontend");
        assert!(!routes(&proxy, 0));
        assert!(!routes(&proxy, 1));
    }
    fn hsts(max_age: u32) -> HstsConfig {
        HstsConfig {
            enabled: Some(true),
            max_age: Some(max_age),
            ..Default::default()
        }
    }

    fn add_with_hsts(
        proxy: &mut HttpsProxy,
        address: SocketAddress,
        interface: Option<&str>,
        token: usize,
        hsts: Option<HstsConfig>,
    ) {
        let mut config = ListenerBuilder::new_https(address)
            .with_interface(interface)
            .to_tls(None)
            .expect("could not build the listener config");
        config.hsts = hsts;
        proxy
            .add_listener(config, Token(token))
            .expect("could not add the listener");
    }

    /// A frontend carrying policy (here, tags) so the router stores it as a
    /// `Route::Frontend` rather than the lightweight `Route::ClusterId`.
    fn tagged_front(address: SocketAddress) -> RequestHttpFrontend {
        RequestHttpFrontend {
            tags: BTreeMap::from([("owner".to_owned(), "team-a".to_owned())]),
            ..front(address)
        }
    }

    /// The `Strict-Transport-Security` value the listener emits for
    /// `example.com/`, if any.
    fn served_hsts(proxy: &HttpsProxy, token: usize) -> Option<String> {
        let route = proxy.listeners[&Token(token)]
            .borrow()
            .fronts
            .lookup("example.com", "/", &Method::Get)
            .expect("the listener must route example.com");
        route
            .headers_response
            .iter()
            .find(|edit| edit.key.eq_ignore_ascii_case(b"strict-transport-security"))
            .map(|edit| String::from_utf8_lossy(&edit.val).into_owned())
    }

    fn patch_hsts(proxy: &HttpsProxy, token: usize, address: SocketAddress, hsts: HstsConfig) {
        proxy.listeners[&Token(token)]
            .borrow_mut()
            .update_config(&UpdateHttpsListenerConfig {
                address,
                hsts: Some(hsts),
                ..Default::default()
            })
            .expect("patch the listener HSTS default");
    }

    /// A patch the worker refuses leaves the HTTPS listener exactly as it was
    /// (sozu-proxy/sozu#1703): its configuration, its rustls context, its
    /// answer registry and the HSTS its frontends serve. Each patch carries
    /// fields that validate — an ALPN change among them, which rebuilds the
    /// rustls context — then one refused field: an `hsts` block without
    /// `enabled`, which the old code checked after committing every other
    /// field, the new ALPN context and the new templates, or an answer
    /// template that does not parse.
    ///
    /// To SEE THIS RED: in `HttpsListener::update_config`, move the
    /// `HstsEnabledRequired` check back to the HSTS block at the end, and
    /// write the fields into `self.config` instead of the candidate copy.
    #[test]
    fn a_rejected_patch_leaves_the_listener_unchanged() {
        use sozu_command::proto::command::{AlpnProtocols, UpdateHttpsListenerConfig};

        let mut proxy = proxy();
        let address = SocketAddress::new_v4(0, 0, 0, 0, provide_port());
        add_with_hsts(&mut proxy, address, None, 0, Some(hsts(100)));
        proxy
            .add_https_frontend(tagged_front(address))
            .expect("add the frontend");

        let valid_prefix = UpdateHttpsListenerConfig {
            address,
            front_timeout: Some(99),
            sozu_id_header: Some("X-Edge-Id".to_owned()),
            alpn_protocols: Some(AlpnProtocols {
                values: vec!["http/1.1".to_owned()],
            }),
            answers: BTreeMap::from([(
                "404".to_owned(),
                "HTTP/1.1 404 Not Found\r\nContent-Length: 0\r\n\r\n".to_owned(),
            )]),
            ..Default::default()
        };
        let rejected = [
            UpdateHttpsListenerConfig {
                hsts: Some(HstsConfig {
                    enabled: None,
                    max_age: Some(200),
                    ..Default::default()
                }),
                ..valid_prefix.clone()
            },
            UpdateHttpsListenerConfig {
                answers: BTreeMap::from([(
                    "503".to_owned(),
                    "not a valid http response".to_owned(),
                )]),
                hsts: Some(hsts(200)),
                ..valid_prefix.clone()
            },
        ];
        for patch in rejected {
            let listener = &proxy.listeners[&Token(0)];
            let config_before = listener.borrow().config.clone();
            let rustls_before = listener.borrow().rustls_details.clone();
            let answers_before = listener.borrow().get_answers().clone();
            listener
                .borrow_mut()
                .update_config(&patch)
                .expect_err("the patch must be refused");
            let listener = listener.borrow();
            assert_eq!(
                listener.config, config_before,
                "a refused patch must leave the listener configuration unchanged"
            );
            assert!(
                Arc::ptr_eq(&rustls_before, &listener.rustls_details),
                "a refused patch must not publish a new rustls context"
            );
            assert!(
                Rc::ptr_eq(&answers_before, listener.get_answers()),
                "a refused patch must not publish a new answer registry"
            );
            drop(listener);
            assert_eq!(
                served_hsts(&proxy, 0).as_deref(),
                Some("max-age=100"),
                "a refused patch must not refresh the frontends' HSTS"
            );
        }

        proxy.listeners[&Token(0)]
            .borrow_mut()
            .update_config(&valid_prefix)
            .expect("the valid prefix alone must apply");
        let listener = proxy.listeners[&Token(0)].borrow();
        assert_eq!(listener.config.front_timeout, 99);
        assert_eq!(listener.config.alpn_protocols, vec!["http/1.1".to_owned()]);
    }

    /// A policy-carrying frontend with no `hsts` of its own, added while the
    /// listener on its address had no HSTS default, is copied into a listener
    /// added later on that address. Each listener serves its own default: the
    /// new listener its HSTS header, the first one none (sozu-proxy/sozu#1691).
    #[test]
    fn a_copied_frontend_without_hsts_inherits_the_new_listener_default() {
        let mut proxy = proxy();
        let address = SocketAddress::new_v4(0, 0, 0, 0, provide_port());
        add_with_hsts(&mut proxy, address, None, 0, None);
        proxy
            .add_https_frontend(tagged_front(address))
            .expect("add the frontend");
        add_with_hsts(&mut proxy, address, Some("lo"), 1, Some(hsts(100)));

        assert_eq!(served_hsts(&proxy, 0), None);
        assert_eq!(
            served_hsts(&proxy, 1).as_deref(),
            Some("max-age=100"),
            "the listener added after the frontend must serve its own HSTS default"
        );

        // Both copies keep following their own listener's default.
        patch_hsts(&proxy, 0, address, hsts(200));
        patch_hsts(&proxy, 1, address, hsts(300));
        assert_eq!(served_hsts(&proxy, 0).as_deref(), Some("max-age=200"));
        assert_eq!(served_hsts(&proxy, 1).as_deref(), Some("max-age=300"));
    }

    /// A frontend with its own `hsts` keeps it on every listener of its
    /// address, whatever their defaults, at copy time and on later patches.
    #[test]
    fn a_frontend_with_explicit_hsts_is_never_overridden_by_a_listener_default() {
        let mut proxy = proxy();
        let address = SocketAddress::new_v4(0, 0, 0, 0, provide_port());
        add_with_hsts(&mut proxy, address, None, 0, Some(hsts(100)));
        proxy
            .add_https_frontend(RequestHttpFrontend {
                hsts: Some(hsts(42)),
                ..tagged_front(address)
            })
            .expect("add the frontend");
        add_with_hsts(&mut proxy, address, Some("lo"), 1, Some(hsts(300)));

        assert_eq!(served_hsts(&proxy, 0).as_deref(), Some("max-age=42"));
        assert_eq!(served_hsts(&proxy, 1).as_deref(), Some("max-age=42"));

        patch_hsts(&proxy, 0, address, hsts(500));
        patch_hsts(&proxy, 1, address, hsts(600));
        assert_eq!(served_hsts(&proxy, 0).as_deref(), Some("max-age=42"));
        assert_eq!(served_hsts(&proxy, 1).as_deref(), Some("max-age=42"));
    }

    /// On a single listener, patching the HSTS default reaches a
    /// policy-carrying frontend that declared no `hsts` of its own, whether
    /// the listener had a default when the frontend was added or not.
    #[test]
    fn a_listener_hsts_patch_refreshes_every_frontend_without_its_own_hsts() {
        for initial in [None, Some(hsts(100))] {
            let mut proxy = proxy();
            let address = SocketAddress::new_v4(0, 0, 0, 0, provide_port());
            add_with_hsts(&mut proxy, address, None, 0, initial);
            proxy
                .add_https_frontend(tagged_front(address))
                .expect("add the frontend");

            patch_hsts(&proxy, 0, address, hsts(700));
            assert_eq!(served_hsts(&proxy, 0).as_deref(), Some("max-age=700"));

            patch_hsts(
                &proxy,
                0,
                address,
                HstsConfig {
                    enabled: Some(false),
                    ..Default::default()
                },
            );
            assert_eq!(served_hsts(&proxy, 0), None);
        }
    }

    /// A self-signed cert usable as a CA root anchor in the verifier tests.
    const TEST_CA_PEM: &str = include_str!("../assets/certificate.pem");

    fn test_crypto_provider() -> Arc<CryptoProvider> {
        Arc::new(default_provider())
    }

    fn https_config_with_client_auth(
        mode: ClientAuthMode,
        cas: &[&str],
        crls: &[&str],
    ) -> HttpsListenerConfig {
        let address = SocketAddress::new_v4(127, 0, 0, 1, 1049);
        let mut config = ListenerBuilder::new_https(address)
            .to_tls(None)
            .expect("default HTTPS listener config");
        config.client_auth = Some(mode as i32);
        config.client_ca_certificates = cas.iter().map(|s| s.to_string()).collect();
        config.client_ca_crls = crls.iter().map(|s| s.to_string()).collect();
        config
    }

    #[test]
    fn client_cert_verifier_none_is_disabled() {
        // NONE (and an absent field) must keep the no-client-auth path.
        let provider = test_crypto_provider();
        let config = https_config_with_client_auth(ClientAuthMode::ClientAuthNone, &[], &[]);
        assert!(
            HttpsListener::client_cert_verifier(&config, &provider)
                .expect("verifier build")
                .is_none()
        );

        let mut absent = config;
        absent.client_auth = None;
        assert!(
            HttpsListener::client_cert_verifier(&absent, &provider)
                .expect("verifier build")
                .is_none(),
            "absent client_auth must decode to NONE"
        );
    }

    #[test]
    fn client_cert_verifier_rejects_unknown_mode() {
        // An unknown (future/garbage) enum value must be rejected, never fold
        // to NONE and silently accept unauthenticated clients.
        let provider = test_crypto_provider();
        let mut config =
            https_config_with_client_auth(ClientAuthMode::ClientAuthRequired, &[TEST_CA_PEM], &[]);
        config.client_auth = Some(999);
        assert!(matches!(
            HttpsListener::client_cert_verifier(&config, &provider),
            Err(ListenerError::ClientAuth(_))
        ));
    }

    #[test]
    fn client_cert_verifier_required_builds_with_ca() {
        let provider = test_crypto_provider();
        let config =
            https_config_with_client_auth(ClientAuthMode::ClientAuthRequired, &[TEST_CA_PEM], &[]);
        assert!(
            HttpsListener::client_cert_verifier(&config, &provider)
                .expect("verifier build")
                .is_some()
        );
    }

    #[test]
    fn client_cert_verifier_optional_builds_with_ca() {
        let provider = test_crypto_provider();
        let config =
            https_config_with_client_auth(ClientAuthMode::ClientAuthOptional, &[TEST_CA_PEM], &[]);
        assert!(
            HttpsListener::client_cert_verifier(&config, &provider)
                .expect("verifier build")
                .is_some()
        );
    }

    #[test]
    fn client_cert_verifier_requires_a_trusted_ca() {
        // A non-NONE mode with an empty CA bundle is a configuration error, not
        // a silently-permissive listener.
        let provider = test_crypto_provider();
        let config = https_config_with_client_auth(ClientAuthMode::ClientAuthRequired, &[], &[]);
        assert!(matches!(
            HttpsListener::client_cert_verifier(&config, &provider),
            Err(ListenerError::ClientAuth(_))
        ));
    }

    #[test]
    fn client_cert_verifier_rejects_malformed_ca() {
        let provider = test_crypto_provider();
        let config = https_config_with_client_auth(
            ClientAuthMode::ClientAuthRequired,
            &["not a pem certificate"],
            &[],
        );
        // A CA entry that parses to zero anchors is a configuration error.
        assert!(matches!(
            HttpsListener::client_cert_verifier(&config, &provider),
            Err(ListenerError::ClientAuth(_))
        ));
    }

    #[test]
    fn client_cert_verifier_rejects_empty_ca_entry_among_valid_ones() {
        // A valid CA followed by an entry contributing no certificate must be
        // rejected, not silently dropped, so the configured trust set is never
        // quietly reduced to a subset.
        let provider = test_crypto_provider();
        let config = https_config_with_client_auth(
            ClientAuthMode::ClientAuthRequired,
            &[TEST_CA_PEM, "not a certificate"],
            &[],
        );
        assert!(matches!(
            HttpsListener::client_cert_verifier(&config, &provider),
            Err(ListenerError::ClientAuth(_))
        ));
    }

    #[test]
    fn client_cert_verifier_rejects_empty_crl_entry() {
        // A configured CRL entry that yields zero CRLs would silently disable
        // revocation; it must be rejected rather than skipped.
        let provider = test_crypto_provider();
        let config = https_config_with_client_auth(
            ClientAuthMode::ClientAuthRequired,
            &[TEST_CA_PEM],
            &["not a crl"],
        );
        assert!(matches!(
            HttpsListener::client_cert_verifier(&config, &provider),
            Err(ListenerError::ClientAuth(_))
        ));
    }

    // ── Client certificate revocation ──
    //
    // The fixtures come from `lib/assets/mtls/generate.sh`: one CA, one
    // client it issued, and CRLs that each leave exactly one reason to accept
    // or reject that client. The verdict is checked on the rustls error, not
    // only on accept/reject, because a handshake rejected for the wrong
    // reason would still look like a pass at the TLS level.

    const MTLS_CA_PEM: &str = include_str!("../assets/mtls/ca-cert.pem");
    const MTLS_CLIENT_PEM: &str = include_str!("../assets/mtls/client-cert.pem");
    /// Issued by the CA, nextUpdate in 2125, revokes nothing.
    const MTLS_CRL_CURRENT: &str = include_str!("../assets/mtls/crl-current.pem");
    /// Issued by the CA, nextUpdate in 2125, revokes the client.
    const MTLS_CRL_REVOKED: &str = include_str!("../assets/mtls/crl-revoked.pem");
    /// Issued by the CA, nextUpdate in January 2020, revokes nothing.
    const MTLS_CRL_EXPIRED: &str = include_str!("../assets/mtls/crl-expired.pem");
    /// Issued by another CA: covers nothing in the client's chain.
    const MTLS_CRL_OTHER_CA: &str = include_str!("../assets/mtls/crl-other-ca.pem");
    /// Two partitions of the CA's list, each with its own
    /// IssuingDistributionPoint, neither covering the client.
    const MTLS_CRL_PARTITION_A: &str = include_str!("../assets/mtls/crl-partition-a.pem");
    const MTLS_CRL_PARTITION_B: &str = include_str!("../assets/mtls/crl-partition-b.pem");

    /// The verdict of a `required` listener trusting the test CA with `crls`
    /// on the test client's certificate, at the current time.
    fn verify_mtls_client(crls: &[&str]) -> Result<(), rustls::Error> {
        verify_mtls_client_at(crls, rustls::pki_types::UnixTime::now())
    }

    /// The same verdict, for a handshake at `time`.
    fn verify_mtls_client_at(
        crls: &[&str],
        time: rustls::pki_types::UnixTime,
    ) -> Result<(), rustls::Error> {
        let config =
            https_config_with_client_auth(ClientAuthMode::ClientAuthRequired, &[MTLS_CA_PEM], crls);
        let verifier = HttpsListener::client_cert_verifier(&config, &test_crypto_provider())
            .expect("a CA and well-formed CRLs must build a verifier")
            .expect("required client auth must install a verifier");
        let client = CertificateDer::from_pem_slice(MTLS_CLIENT_PEM.as_bytes())
            .expect("the client fixture is a PEM certificate");
        verifier.verify_client_cert(&client, &[], time).map(|_| ())
    }

    /// Whether a `required` listener can be built with `crls`, and the
    /// reason when it cannot.
    fn build_mtls_listener(crls: &[&str]) -> Result<(), String> {
        let config =
            https_config_with_client_auth(ClientAuthMode::ClientAuthRequired, &[MTLS_CA_PEM], crls);
        match HttpsListener::client_cert_verifier(&config, &test_crypto_provider()) {
            Ok(_) => Ok(()),
            Err(ListenerError::ClientAuth(reason)) => Err(reason),
            Err(other) => panic!("unexpected listener error {other:?}"),
        }
    }

    #[test]
    fn client_revocation_accepts_a_client_no_crl_revokes() {
        assert_eq!(
            verify_mtls_client(&[]),
            Ok(()),
            "precondition: the client chains to the CA"
        );
        assert_eq!(
            verify_mtls_client(&[MTLS_CRL_CURRENT]),
            Ok(()),
            "a current CRL from the client's issuer that does not list it must not reject it"
        );
    }

    #[test]
    fn client_revocation_rejects_a_revoked_client() {
        // The CRL is current, so only the serial lookup can reject the client.
        // Without `with_crls`, the client would be accepted.
        assert_eq!(
            verify_mtls_client(&[MTLS_CRL_REVOKED]),
            Err(rustls::Error::InvalidCertificate(
                rustls::CertificateError::Revoked
            ))
        );
    }

    #[test]
    fn client_revocation_refuses_an_expired_crl_only_where_the_operator_states_it() {
        // The main process refuses a CRL already past its nextUpdate in what
        // an operator states: it would reject every client it covers.
        let now = i64::try_from(
            std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .expect("a clock after 1970")
                .as_secs(),
        )
        .expect("a clock within i64");
        let refused = HttpsListener::check_crls_current(&[MTLS_CRL_EXPIRED.to_owned()], now);
        assert!(
            matches!(refused, Err(ListenerError::ClientAuth(ref reason)) if reason.contains("expired")),
            "an expired CRL must be refused when stated, got {refused:?}"
        );
        assert!(
            HttpsListener::check_crls_current(
                &[MTLS_CRL_CURRENT.to_owned(), MTLS_CRL_OTHER_CA.to_owned()],
                now
            )
            .is_ok()
        );
        // A worker still builds a listener whose CRL lapsed while it ran (a
        // restarted worker replaying the state), so a later reload has a
        // listener to patch; the lapsed CRL rejects clients at handshake.
        assert_eq!(build_mtls_listener(&[MTLS_CRL_EXPIRED]), Ok(()));
        let config = https_config_with_client_auth(
            ClientAuthMode::ClientAuthRequired,
            &[MTLS_CA_PEM],
            &[MTLS_CRL_EXPIRED],
        );
        assert!(HttpsListener::try_new(config, Token(0)).is_ok());
    }

    #[test]
    fn client_revocation_rejects_a_client_once_its_crl_has_lapsed() {
        // A CRL current when the listener was built lapses while it runs.
        // In June 2125 the current CRL (nextUpdate January 2125) has lapsed
        // and the client certificate (notAfter 2126) has not, so only the
        // CRL expiry can reject the client. Without
        // `enforce_revocation_expiration`, rustls keeps trusting the stale CRL
        // and accepts it.
        let june_2125 =
            rustls::pki_types::UnixTime::since_unix_epoch(Duration::from_secs(4_905_100_800));
        let verdict = verify_mtls_client_at(&[MTLS_CRL_CURRENT], june_2125);
        assert!(
            matches!(
                verdict,
                Err(rustls::Error::InvalidCertificate(
                    rustls::CertificateError::ExpiredRevocationList
                        | rustls::CertificateError::ExpiredRevocationListContext { .. }
                ))
            ),
            "a CRL past its nextUpdate must reject the client, got {verdict:?}"
        );
        // Positive space: without CRLs the client is still valid then, so the
        // rejection above is the CRL expiry and nothing else.
        assert_eq!(verify_mtls_client_at(&[], june_2125), Ok(()));
    }

    #[test]
    fn client_revocation_rejects_a_client_no_configured_crl_covers() {
        // Once any CRL is configured, a client whose issuer no CRL covers has
        // an unknown revocation status, which rustls's default
        // `UnknownStatusPolicy::Deny` rejects.
        assert_eq!(
            verify_mtls_client(&[MTLS_CRL_OTHER_CA]),
            Err(rustls::Error::InvalidCertificate(
                rustls::CertificateError::UnknownRevocationStatus
            ))
        );
        // Adding the issuer's own current CRL restores the verdict.
        assert_eq!(
            verify_mtls_client(&[MTLS_CRL_OTHER_CA, MTLS_CRL_CURRENT]),
            Ok(())
        );
    }

    #[test]
    fn client_revocation_refuses_two_crls_of_one_issuer_with_overlapping_scopes() {
        // webpki would only read the first of them, so the order alone would
        // decide: listing the revoking CRL second accepts the revoked client.
        // Every order must fail the listener instead.
        for crls in [
            vec![MTLS_CRL_CURRENT, MTLS_CRL_REVOKED],
            vec![MTLS_CRL_REVOKED, MTLS_CRL_CURRENT],
            // A full CRL covers every partition of its CA.
            vec![MTLS_CRL_CURRENT, MTLS_CRL_PARTITION_A],
            vec![MTLS_CRL_PARTITION_A, MTLS_CRL_CURRENT],
            // The same partition twice.
            vec![MTLS_CRL_PARTITION_A, MTLS_CRL_PARTITION_A],
        ] {
            let refused = build_mtls_listener(&crls);
            assert!(
                refused
                    .as_ref()
                    .is_err_and(|reason| reason.contains("overlapping")),
                "overlapping CRLs of one issuer must fail the listener, got {refused:?}"
            );
        }
        // Two CRLs in one configured entry count the same as two entries.
        assert!(build_mtls_listener(&[&format!("{MTLS_CRL_CURRENT}{MTLS_CRL_REVOKED}")]).is_err());
    }

    #[test]
    fn client_revocation_takes_the_partitions_of_one_issuer() {
        // Partitions told apart by their distribution point cover disjoint
        // certificates, so a CA publishing its list that way stays usable.
        assert_eq!(
            build_mtls_listener(&[MTLS_CRL_PARTITION_A, MTLS_CRL_PARTITION_B]),
            Ok(())
        );
    }

    #[test]
    fn client_revocation_takes_one_crl_per_issuer() {
        // Positive space of the rule above: CRLs from distinct issuers are
        // all kept, and none shadows another.
        assert_eq!(
            verify_mtls_client(&[MTLS_CRL_OTHER_CA, MTLS_CRL_REVOKED]),
            Err(rustls::Error::InvalidCertificate(
                rustls::CertificateError::Revoked
            ))
        );
        assert_eq!(
            verify_mtls_client(&[MTLS_CRL_REVOKED, MTLS_CRL_OTHER_CA]),
            Err(rustls::Error::InvalidCertificate(
                rustls::CertificateError::Revoked
            ))
        );
    }

    /// The in-place refresh of a running listener's client authentication
    /// policy: the patch replaces the policy and rebuilds the rustls context
    /// that holds the verifier; a policy the verifier cannot be built from
    /// leaves the listener exactly as it was. Its effect on handshakes is
    /// covered by `test_mtls_policy_patch_*` in `e2e/src/tests/tls_tests.rs`.
    #[test]
    fn a_client_auth_policy_patch_rebuilds_the_listener_verifier() {
        let config = https_config_with_client_auth(
            ClientAuthMode::ClientAuthRequired,
            &[MTLS_CA_PEM],
            &[MTLS_CRL_CURRENT],
        );
        let mut listener =
            HttpsListener::try_new(config.clone(), Token(0)).expect("build the mTLS listener");
        let original_context = listener.rustls_details.clone();

        let refreshed = HttpsListenerConfig {
            client_ca_crls: vec![MTLS_CRL_REVOKED.to_owned()],
            ..config.clone()
        }
        .client_auth_policy();
        listener
            .update_config(&UpdateHttpsListenerConfig {
                address: config.address,
                client_auth_policy: Some(refreshed.clone()),
                ..Default::default()
            })
            .expect("a buildable policy must be applied");
        assert_eq!(listener.config.client_auth_policy(), refreshed);
        assert!(
            !Arc::ptr_eq(&listener.rustls_details, &original_context),
            "the verifier lives in the rustls context, which must be rebuilt"
        );

        let applied_context = listener.rustls_details.clone();
        let unbuildable = ClientAuthPolicy {
            client_auth: Some(ClientAuthMode::ClientAuthRequired as i32),
            client_ca_certificates: vec![],
            client_ca_crls: vec![],
        };
        assert!(
            listener
                .update_config(&UpdateHttpsListenerConfig {
                    address: config.address,
                    client_auth_policy: Some(unbuildable.clone()),
                    ..Default::default()
                })
                .is_err(),
            "required client auth with no trusted CA must be refused"
        );
        assert!(HttpsListener::validate_client_auth_policy(&unbuildable).is_err());
        assert_eq!(
            listener.config.client_auth_policy(),
            refreshed,
            "a refused policy leaves the applied one in place"
        );
        assert!(Arc::ptr_eq(&listener.rustls_details, &applied_context));
    }
}