nono_proxy/

server.rs

//! Proxy server: TCP listener, connection dispatch, and lifecycle.
//!
//! The server binds to `127.0.0.1:0` (OS-assigned port), accepts TCP
//! connections, reads the first HTTP line to determine the mode, and
//! dispatches to the appropriate handler.
//!
//! CONNECT method -> [`connect`] or [`external`] handler
//! Other methods  -> [`reverse`] handler (credential injection)

use crate::audit;
use crate::config::ProxyConfig;
use crate::connect;
use crate::credential::CredentialStore;
use crate::error::{ProxyError, Result};
use crate::external;
use crate::filter::ProxyFilter;
use crate::reverse;
use crate::token;
use std::net::SocketAddr;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
use tokio::net::TcpListener;
use tokio::sync::watch;
use tracing::{debug, info, warn};
use zeroize::Zeroizing;

/// Maximum total size of HTTP headers (64 KiB). Prevents OOM from
/// malicious clients sending unbounded header data.
const MAX_HEADER_SIZE: usize = 64 * 1024;

/// Handle returned when the proxy server starts.
///
/// Contains the assigned port, session token, and a shutdown channel.
/// Drop the handle or send to `shutdown_tx` to stop the proxy.
pub struct ProxyHandle {
    /// The actual port the proxy is listening on
    pub port: u16,
    /// Session token for client authentication
    pub token: Zeroizing<String>,
    /// Shared in-memory network audit log
    audit_log: audit::SharedAuditLog,
    /// Send `true` to trigger graceful shutdown
    shutdown_tx: watch::Sender<bool>,
    /// Route prefixes that have credentials actually loaded.
    /// Routes whose credentials were unavailable are excluded so we
    /// don't inject phantom tokens that shadow valid external credentials.
    loaded_routes: std::collections::HashSet<String>,
    /// Non-credential allowed hosts that should bypass the proxy (NO_PROXY).
    /// Computed at startup: `allowed_hosts` minus credential upstream hosts.
    no_proxy_hosts: Vec<String>,
}

impl ProxyHandle {
    /// Signal the proxy to shut down gracefully.
    pub fn shutdown(&self) {
        let _ = self.shutdown_tx.send(true);
    }

    /// Drain and return collected network audit events.
    #[must_use]
    pub fn drain_audit_events(&self) -> Vec<nono::undo::NetworkAuditEvent> {
        audit::drain_audit_events(&self.audit_log)
    }

    /// Environment variables to inject into the child process.
    ///
    /// The proxy URL includes `nono:<token>@` userinfo so that standard HTTP
    /// clients (curl, Python requests, etc.) automatically send
    /// `Proxy-Authorization: Basic ...` on every request. The raw token is
    /// also provided via `NONO_PROXY_TOKEN` for nono-aware clients that
    /// prefer Bearer auth.
    #[must_use]
    pub fn env_vars(&self) -> Vec<(String, String)> {
        let proxy_url = format!("http://nono:{}@127.0.0.1:{}", &*self.token, self.port);

        // Build NO_PROXY: always include loopback, plus non-credential
        // allowed hosts. Credential upstreams are excluded so their traffic
        // goes through the reverse proxy for L7 filtering + injection.
        let mut no_proxy_parts = vec!["localhost".to_string(), "127.0.0.1".to_string()];
        for host in &self.no_proxy_hosts {
            // Strip port for NO_PROXY (most HTTP clients match on hostname).
            // Handle IPv6 brackets: "[::1]:443" → "[::1]", "host:443" → "host"
            let hostname = if host.contains("]:") {
                // IPv6 with port: split at "]:port"
                host.rsplit_once("]:")
                    .map(|(h, _)| format!("{}]", h))
                    .unwrap_or_else(|| host.clone())
            } else {
                host.rsplit_once(':')
                    .and_then(|(h, p)| p.parse::<u16>().ok().map(|_| h.to_string()))
                    .unwrap_or_else(|| host.clone())
            };
            if !no_proxy_parts.contains(&hostname.to_string()) {
                no_proxy_parts.push(hostname.to_string());
            }
        }
        let no_proxy = no_proxy_parts.join(",");

        let mut vars = vec![
            ("HTTP_PROXY".to_string(), proxy_url.clone()),
            ("HTTPS_PROXY".to_string(), proxy_url.clone()),
            ("NO_PROXY".to_string(), no_proxy.clone()),
            ("NONO_PROXY_TOKEN".to_string(), self.token.to_string()),
        ];

        // Lowercase variants for compatibility
        vars.push(("http_proxy".to_string(), proxy_url.clone()));
        vars.push(("https_proxy".to_string(), proxy_url));
        vars.push(("no_proxy".to_string(), no_proxy));

        // Node.js v22.21.0+ / v24.0.0+ requires this flag for native fetch() to use HTTP_PROXY
        vars.push(("NODE_USE_ENV_PROXY".to_string(), "1".to_string()));

        vars
    }

    /// Environment variables for reverse proxy credential routes.
    ///
    /// Returns two types of env vars per route:
    /// 1. SDK base URL overrides (e.g., `OPENAI_BASE_URL=http://127.0.0.1:PORT/openai`)
    /// 2. SDK API key vars set to the session token (e.g., `OPENAI_API_KEY=<token>`)
    ///
    /// The SDK sends the session token as its "API key" (phantom token pattern).
    /// The proxy validates this token and swaps it for the real credential.
    #[must_use]
    pub fn credential_env_vars(&self, config: &ProxyConfig) -> Vec<(String, String)> {
        let mut vars = Vec::new();
        for route in &config.routes {
            // Base URL override (e.g., OPENAI_BASE_URL)
            let base_url_name = format!("{}_BASE_URL", route.prefix.to_uppercase());
            let url = format!("http://127.0.0.1:{}/{}", self.port, route.prefix);
            vars.push((base_url_name, url));

            // Only inject phantom token env vars for routes whose credentials
            // were actually loaded. If a credential was unavailable (e.g.,
            // GITHUB_TOKEN env var not set), injecting a phantom token would
            // shadow valid credentials from other sources (keyring, gh auth).
            if !self.loaded_routes.contains(&route.prefix) {
                continue;
            }

            // API key set to session token (phantom token pattern).
            // Use explicit env_var if set (required for URI manager refs), otherwise
            // fall back to uppercasing the credential_key (e.g., "openai_api_key" -> "OPENAI_API_KEY").
            if let Some(ref env_var) = route.env_var {
                vars.push((env_var.clone(), self.token.to_string()));
            } else if let Some(ref cred_key) = route.credential_key {
                let api_key_name = cred_key.to_uppercase();
                vars.push((api_key_name, self.token.to_string()));
            }
        }
        vars
    }
}

/// Shared state for the proxy server.
struct ProxyState {
    filter: ProxyFilter,
    session_token: Zeroizing<String>,
    credential_store: CredentialStore,
    config: ProxyConfig,
    /// Shared TLS connector for upstream connections (reverse proxy mode).
    /// Created once at startup to avoid rebuilding the root cert store per request.
    tls_connector: tokio_rustls::TlsConnector,
    /// Active connection count for connection limiting.
    active_connections: AtomicUsize,
    /// Shared network audit log for this proxy session.
    audit_log: audit::SharedAuditLog,
    /// Matcher for hosts that bypass the external proxy and route direct.
    /// Built once at startup from `ExternalProxyConfig.bypass_hosts`.
    bypass_matcher: external::BypassMatcher,
}

/// Start the proxy server.
///
/// Binds to `config.bind_addr:config.bind_port` (port 0 = OS-assigned),
/// generates a session token, and begins accepting connections.
///
/// Returns a `ProxyHandle` with the assigned port and session token.
/// The server runs until the handle is dropped or `shutdown()` is called.
pub async fn start(config: ProxyConfig) -> Result<ProxyHandle> {
    // Generate session token
    let session_token = token::generate_session_token()?;

    // Bind listener
    let bind_addr = SocketAddr::new(config.bind_addr, config.bind_port);
    let listener = TcpListener::bind(bind_addr)
        .await
        .map_err(|e| ProxyError::Bind {
            addr: bind_addr.to_string(),
            source: e,
        })?;

    let local_addr = listener.local_addr().map_err(|e| ProxyError::Bind {
        addr: bind_addr.to_string(),
        source: e,
    })?;
    let port = local_addr.port();

    info!("Proxy server listening on {}", local_addr);

    // Load credentials for reverse proxy routes
    let credential_store = if config.routes.is_empty() {
        CredentialStore::empty()
    } else {
        CredentialStore::load(&config.routes)?
    };
    let loaded_routes = credential_store.loaded_prefixes();

    // Build filter
    let filter = if config.allowed_hosts.is_empty() {
        ProxyFilter::allow_all()
    } else {
        ProxyFilter::new(&config.allowed_hosts)
    };

    // Build shared TLS connector (root cert store is expensive to construct).
    // Use the ring provider explicitly to avoid ambiguity when multiple
    // crypto providers are in the dependency tree.
    let mut root_store = rustls::RootCertStore::empty();
    root_store.extend(webpki_roots::TLS_SERVER_ROOTS.iter().cloned());
    let tls_config = rustls::ClientConfig::builder_with_provider(Arc::new(
        rustls::crypto::ring::default_provider(),
    ))
    .with_safe_default_protocol_versions()
    .map_err(|e| ProxyError::Config(format!("TLS config error: {}", e)))?
    .with_root_certificates(root_store)
    .with_no_client_auth();
    let tls_connector = tokio_rustls::TlsConnector::from(Arc::new(tls_config));

    // Build bypass matcher from external proxy config (once, not per-request)
    let bypass_matcher = config
        .external_proxy
        .as_ref()
        .map(|ext| external::BypassMatcher::new(&ext.bypass_hosts))
        .unwrap_or_else(|| external::BypassMatcher::new(&[]));

    // Shutdown channel
    let (shutdown_tx, shutdown_rx) = watch::channel(false);
    let audit_log = audit::new_audit_log();

    // Compute NO_PROXY hosts: allowed_hosts minus credential upstreams.
    // Non-credential hosts bypass the proxy (direct connection, still
    // Landlock-enforced). Credential upstreams must go through the proxy
    // for L7 path filtering and credential injection.
    let credential_hosts = credential_store.credential_upstream_hosts();
    let no_proxy_hosts: Vec<String> = config
        .allowed_hosts
        .iter()
        .filter(|host| {
            let normalised = {
                let h = host.to_lowercase();
                if h.contains(':') {
                    h
                } else {
                    format!("{}:443", h)
                }
            };
            !credential_hosts.contains(&normalised)
        })
        .cloned()
        .collect();

    if !no_proxy_hosts.is_empty() {
        debug!("Smart NO_PROXY bypass hosts: {:?}", no_proxy_hosts);
    }

    let state = Arc::new(ProxyState {
        filter,
        session_token: session_token.clone(),
        credential_store,
        config,
        tls_connector,
        active_connections: AtomicUsize::new(0),
        audit_log: Arc::clone(&audit_log),
        bypass_matcher,
    });

    // Spawn accept loop as a task within the current runtime.
    // The caller MUST ensure this runtime is being driven (e.g., via
    // a dedicated thread calling block_on or a multi-thread runtime).
    tokio::spawn(accept_loop(listener, state, shutdown_rx));

    Ok(ProxyHandle {
        port,
        token: session_token,
        audit_log,
        shutdown_tx,
        loaded_routes,
        no_proxy_hosts,
    })
}

/// Accept loop: listen for connections until shutdown.
async fn accept_loop(
    listener: TcpListener,
    state: Arc<ProxyState>,
    mut shutdown_rx: watch::Receiver<bool>,
) {
    loop {
        tokio::select! {
            result = listener.accept() => {
                match result {
                    Ok((stream, addr)) => {
                        // Connection limit enforcement
                        let max = state.config.max_connections;
                        if max > 0 {
                            let current = state.active_connections.load(Ordering::Relaxed);
                            if current >= max {
                                warn!("Connection limit reached ({}/{}), rejecting {}", current, max, addr);
                                // Drop the stream (connection refused)
                                drop(stream);
                                continue;
                            }
                        }
                        state.active_connections.fetch_add(1, Ordering::Relaxed);

                        debug!("Accepted connection from {}", addr);
                        let state = Arc::clone(&state);
                        tokio::spawn(async move {
                            if let Err(e) = handle_connection(stream, &state).await {
                                debug!("Connection handler error: {}", e);
                            }
                            state.active_connections.fetch_sub(1, Ordering::Relaxed);
                        });
                    }
                    Err(e) => {
                        warn!("Accept error: {}", e);
                    }
                }
            }
            _ = shutdown_rx.changed() => {
                if *shutdown_rx.borrow() {
                    info!("Proxy server shutting down");
                    return;
                }
            }
        }
    }
}

/// Handle a single client connection.
///
/// Reads the first HTTP line to determine the proxy mode:
/// - CONNECT method -> tunnel (Mode 1 or 3)
/// - Other methods  -> reverse proxy (Mode 2)
async fn handle_connection(mut stream: tokio::net::TcpStream, state: &ProxyState) -> Result<()> {
    // Read the first line and headers through a BufReader.
    // We keep the BufReader alive until we've consumed the full header
    // to prevent data loss (BufReader may read ahead into the body).
    let mut buf_reader = BufReader::new(&mut stream);
    let mut first_line = String::new();
    buf_reader.read_line(&mut first_line).await?;

    if first_line.is_empty() {
        return Ok(()); // Client disconnected
    }

    // Read remaining headers (up to empty line), with size limit to prevent OOM.
    let mut header_bytes = Vec::new();
    loop {
        let mut line = String::new();
        let n = buf_reader.read_line(&mut line).await?;
        if n == 0 || line.trim().is_empty() {
            break;
        }
        header_bytes.extend_from_slice(line.as_bytes());
        if header_bytes.len() > MAX_HEADER_SIZE {
            drop(buf_reader);
            let response = "HTTP/1.1 431 Request Header Fields Too Large\r\n\r\n";
            stream.write_all(response.as_bytes()).await?;
            return Ok(());
        }
    }

    // Extract any data buffered beyond headers before dropping BufReader.
    // BufReader may have read ahead into the request body. We capture
    // those bytes and pass them to the reverse proxy handler so no body
    // data is lost. For CONNECT requests this is always empty (no body).
    let buffered = buf_reader.buffer().to_vec();
    drop(buf_reader);

    let first_line = first_line.trim_end();

    // Dispatch by method
    if first_line.starts_with("CONNECT ") {
        // Block CONNECT tunnels to credential upstreams. These must go
        // through the reverse proxy path so L7 path filtering and
        // credential injection are enforced. A CONNECT tunnel would
        // bypass both (raw TLS pipe, proxy never sees HTTP method/path).
        if !state.credential_store.is_empty() {
            if let Some(authority) = first_line.split_whitespace().nth(1) {
                // Normalise authority to host:port. Handle IPv6 brackets:
                // "[::1]:443" already has port, "[::1]" needs default, "host:443" has port.
                let host_port = if authority.starts_with('[') {
                    // IPv6 literal
                    if authority.contains("]:") {
                        authority.to_lowercase()
                    } else {
                        format!("{}:443", authority.to_lowercase())
                    }
                } else if authority.contains(':') {
                    authority.to_lowercase()
                } else {
                    format!("{}:443", authority.to_lowercase())
                };
                if state.credential_store.is_credential_upstream(&host_port) {
                    let (host, port) = host_port
                        .rsplit_once(':')
                        .map(|(h, p)| (h, p.parse::<u16>().unwrap_or(443)))
                        .unwrap_or((&host_port, 443));
                    warn!(
                        "Blocked CONNECT to credential upstream {} — use reverse proxy path instead",
                        authority
                    );
                    audit::log_denied(
                        Some(&state.audit_log),
                        audit::ProxyMode::Connect,
                        host,
                        port,
                        "credential upstream: CONNECT bypasses L7 filtering",
                    );
                    let response = "HTTP/1.1 403 Forbidden\r\nContent-Length: 0\r\n\r\n";
                    stream.write_all(response.as_bytes()).await?;
                    return Ok(());
                }
            }
        }

        // Check if external proxy is configured and host is not bypassed
        let use_external = if let Some(ref ext_config) = state.config.external_proxy {
            if state.bypass_matcher.is_empty() {
                Some(ext_config)
            } else {
                // Parse host from CONNECT line to check bypass
                let host = first_line
                    .split_whitespace()
                    .nth(1)
                    .and_then(|authority| {
                        authority
                            .rsplit_once(':')
                            .map(|(h, _)| h)
                            .or(Some(authority))
                    })
                    .unwrap_or("");
                if state.bypass_matcher.matches(host) {
                    debug!("Bypassing external proxy for {}", host);
                    None
                } else {
                    Some(ext_config)
                }
            }
        } else {
            None
        };

        if let Some(ext_config) = use_external {
            external::handle_external_proxy(
                first_line,
                &mut stream,
                &header_bytes,
                &state.filter,
                &state.session_token,
                ext_config,
                Some(&state.audit_log),
            )
            .await
        } else if state.config.external_proxy.is_some() {
            // Bypass route: enforce strict session token validation before
            // routing direct. Without this, bypassed hosts would inherit
            // connect::handle_connect()'s lenient auth (which tolerates
            // missing Proxy-Authorization for Node.js undici compat).
            token::validate_proxy_auth(&header_bytes, &state.session_token)?;
            connect::handle_connect(
                first_line,
                &mut stream,
                &state.filter,
                &state.session_token,
                &header_bytes,
                Some(&state.audit_log),
            )
            .await
        } else {
            connect::handle_connect(
                first_line,
                &mut stream,
                &state.filter,
                &state.session_token,
                &header_bytes,
                Some(&state.audit_log),
            )
            .await
        }
    } else if !state.credential_store.is_empty() {
        // Non-CONNECT request with credential routes -> reverse proxy
        let ctx = reverse::ReverseProxyCtx {
            credential_store: &state.credential_store,
            session_token: &state.session_token,
            filter: &state.filter,
            tls_connector: &state.tls_connector,
            audit_log: Some(&state.audit_log),
        };
        reverse::handle_reverse_proxy(first_line, &mut stream, &header_bytes, &ctx, &buffered).await
    } else {
        // No credential routes configured, reject non-CONNECT requests
        let response = "HTTP/1.1 400 Bad Request\r\n\r\n";
        stream.write_all(response.as_bytes()).await?;
        Ok(())
    }
}

#[cfg(test)]
#[allow(clippy::unwrap_used)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_proxy_starts_and_binds() {
        let config = ProxyConfig::default();
        let handle = start(config).await.unwrap();

        // Port should be non-zero (OS-assigned)
        assert!(handle.port > 0);
        // Token should be 64 hex chars
        assert_eq!(handle.token.len(), 64);

        // Shutdown
        handle.shutdown();
    }

    #[tokio::test]
    async fn test_proxy_env_vars() {
        let config = ProxyConfig::default();
        let handle = start(config).await.unwrap();

        let vars = handle.env_vars();
        let http_proxy = vars.iter().find(|(k, _)| k == "HTTP_PROXY");
        assert!(http_proxy.is_some());
        assert!(http_proxy.unwrap().1.starts_with("http://nono:"));

        let token_var = vars.iter().find(|(k, _)| k == "NONO_PROXY_TOKEN");
        assert!(token_var.is_some());
        assert_eq!(token_var.unwrap().1.len(), 64);

        handle.shutdown();
    }

    #[tokio::test]
    async fn test_proxy_credential_env_vars() {
        let config = ProxyConfig {
            routes: vec![crate::config::RouteConfig {
                prefix: "openai".to_string(),
                upstream: "https://api.openai.com".to_string(),
                credential_key: None,
                inject_mode: crate::config::InjectMode::Header,
                inject_header: "Authorization".to_string(),
                credential_format: "Bearer {}".to_string(),
                path_pattern: None,
                path_replacement: None,
                query_param_name: None,
                env_var: None,
                endpoint_rules: vec![],
                tls_ca: None,
            }],
            ..Default::default()
        };
        let handle = start(config.clone()).await.unwrap();

        let vars = handle.credential_env_vars(&config);
        assert_eq!(vars.len(), 1);
        assert_eq!(vars[0].0, "OPENAI_BASE_URL");
        assert!(vars[0].1.contains("/openai"));

        handle.shutdown();
    }

    #[test]
    fn test_proxy_credential_env_vars_fallback_to_uppercase_key() {
        // When env_var is None and credential_key is set, the env var name
        // should be derived from uppercasing credential_key. This is the
        // backward-compatible path for keyring-backed credentials.
        let (shutdown_tx, _) = tokio::sync::watch::channel(false);
        let handle = ProxyHandle {
            port: 12345,
            token: Zeroizing::new("test_token".to_string()),
            audit_log: audit::new_audit_log(),
            shutdown_tx,
            loaded_routes: ["openai".to_string()].into_iter().collect(),
            no_proxy_hosts: Vec::new(),
        };
        let config = ProxyConfig {
            routes: vec![crate::config::RouteConfig {
                prefix: "openai".to_string(),
                upstream: "https://api.openai.com".to_string(),
                credential_key: Some("openai_api_key".to_string()),
                inject_mode: crate::config::InjectMode::Header,
                inject_header: "Authorization".to_string(),
                credential_format: "Bearer {}".to_string(),
                path_pattern: None,
                path_replacement: None,
                query_param_name: None,
                env_var: None, // No explicit env_var — should fall back to uppercase
                endpoint_rules: vec![],
                tls_ca: None,
            }],
            ..Default::default()
        };

        let vars = handle.credential_env_vars(&config);
        assert_eq!(vars.len(), 2); // BASE_URL + API_KEY

        // Should derive OPENAI_API_KEY from uppercasing "openai_api_key"
        let api_key_var = vars.iter().find(|(k, _)| k == "OPENAI_API_KEY");
        assert!(
            api_key_var.is_some(),
            "Should derive env var name from credential_key.to_uppercase()"
        );

        let (_, val) = api_key_var.expect("OPENAI_API_KEY should exist");
        assert_eq!(val, "test_token");
    }

    #[test]
    fn test_proxy_credential_env_vars_with_explicit_env_var() {
        // When env_var is set on a route, it should be used instead of
        // deriving from credential_key. This is essential for URI manager
        // credential refs (e.g., op://, apple-password://)
        // where uppercasing produces nonsensical env var names.
        //
        // We construct a ProxyHandle directly to test env var generation
        // without starting a real proxy (which would try to load credentials).
        let (shutdown_tx, _) = tokio::sync::watch::channel(false);
        let handle = ProxyHandle {
            port: 12345,
            token: Zeroizing::new("test_token".to_string()),
            audit_log: audit::new_audit_log(),
            shutdown_tx,
            loaded_routes: ["openai".to_string()].into_iter().collect(),
            no_proxy_hosts: Vec::new(),
        };
        let config = ProxyConfig {
            routes: vec![crate::config::RouteConfig {
                prefix: "openai".to_string(),
                upstream: "https://api.openai.com".to_string(),
                credential_key: Some("op://Development/OpenAI/credential".to_string()),
                inject_mode: crate::config::InjectMode::Header,
                inject_header: "Authorization".to_string(),
                credential_format: "Bearer {}".to_string(),
                path_pattern: None,
                path_replacement: None,
                query_param_name: None,
                env_var: Some("OPENAI_API_KEY".to_string()),
                endpoint_rules: vec![],
                tls_ca: None,
            }],
            ..Default::default()
        };

        let vars = handle.credential_env_vars(&config);
        assert_eq!(vars.len(), 2); // BASE_URL + API_KEY

        let api_key_var = vars.iter().find(|(k, _)| k == "OPENAI_API_KEY");
        assert!(
            api_key_var.is_some(),
            "Should use explicit env_var name, not derive from credential_key"
        );

        // Verify the value is the phantom token, not the real credential
        let (_, val) = api_key_var.expect("OPENAI_API_KEY var should exist");
        assert_eq!(val, "test_token");

        // Verify no nonsensical OP:// env var was generated
        let bad_var = vars.iter().find(|(k, _)| k.starts_with("OP://"));
        assert!(
            bad_var.is_none(),
            "Should not generate env var from op:// URI uppercase"
        );
    }

    #[test]
    fn test_proxy_credential_env_vars_skips_unloaded_routes() {
        // When a credential is unavailable (e.g., GITHUB_TOKEN not set),
        // the route should NOT inject a phantom token env var. Otherwise
        // the phantom token shadows valid credentials from other sources
        // like the system keyring. See: #234
        let (shutdown_tx, _) = tokio::sync::watch::channel(false);
        let handle = ProxyHandle {
            port: 12345,
            token: Zeroizing::new("test_token".to_string()),
            audit_log: audit::new_audit_log(),
            shutdown_tx,
            // Only "openai" was loaded; "github" credential was unavailable
            loaded_routes: ["openai".to_string()].into_iter().collect(),
            no_proxy_hosts: Vec::new(),
        };
        let config = ProxyConfig {
            routes: vec![
                crate::config::RouteConfig {
                    prefix: "openai".to_string(),
                    upstream: "https://api.openai.com".to_string(),
                    credential_key: Some("openai_api_key".to_string()),
                    inject_mode: crate::config::InjectMode::Header,
                    inject_header: "Authorization".to_string(),
                    credential_format: "Bearer {}".to_string(),
                    path_pattern: None,
                    path_replacement: None,
                    query_param_name: None,
                    env_var: None,
                    endpoint_rules: vec![],
                    tls_ca: None,
                },
                crate::config::RouteConfig {
                    prefix: "github".to_string(),
                    upstream: "https://api.github.com".to_string(),
                    credential_key: Some("env://GITHUB_TOKEN".to_string()),
                    inject_mode: crate::config::InjectMode::Header,
                    inject_header: "Authorization".to_string(),
                    credential_format: "token {}".to_string(),
                    path_pattern: None,
                    path_replacement: None,
                    query_param_name: None,
                    env_var: Some("GITHUB_TOKEN".to_string()),
                    endpoint_rules: vec![],
                    tls_ca: None,
                },
            ],
            ..Default::default()
        };

        let vars = handle.credential_env_vars(&config);

        // openai should have BASE_URL + API_KEY (credential loaded)
        let openai_base = vars.iter().find(|(k, _)| k == "OPENAI_BASE_URL");
        assert!(openai_base.is_some(), "loaded route should have BASE_URL");
        let openai_key = vars.iter().find(|(k, _)| k == "OPENAI_API_KEY");
        assert!(openai_key.is_some(), "loaded route should have API key");

        // github should have BASE_URL (always set for declared routes) but
        // must NOT have GITHUB_TOKEN (credential was not loaded)
        let github_base = vars.iter().find(|(k, _)| k == "GITHUB_BASE_URL");
        assert!(
            github_base.is_some(),
            "declared route should still have BASE_URL"
        );
        let github_token = vars.iter().find(|(k, _)| k == "GITHUB_TOKEN");
        assert!(
            github_token.is_none(),
            "unloaded route must not inject phantom GITHUB_TOKEN"
        );
    }

    #[test]
    fn test_no_proxy_excludes_credential_upstreams() {
        let (shutdown_tx, _) = tokio::sync::watch::channel(false);
        let handle = ProxyHandle {
            port: 12345,
            token: Zeroizing::new("test_token".to_string()),
            audit_log: audit::new_audit_log(),
            shutdown_tx,
            loaded_routes: std::collections::HashSet::new(),
            no_proxy_hosts: vec![
                "nats.internal:4222".to_string(),
                "opencode.internal:4096".to_string(),
            ],
        };

        let vars = handle.env_vars();
        let no_proxy = vars.iter().find(|(k, _)| k == "NO_PROXY").unwrap();
        assert!(
            no_proxy.1.contains("nats.internal"),
            "non-credential host should be in NO_PROXY"
        );
        assert!(
            no_proxy.1.contains("opencode.internal"),
            "non-credential host should be in NO_PROXY"
        );
        assert!(
            no_proxy.1.contains("localhost"),
            "localhost should always be in NO_PROXY"
        );
    }

    #[test]
    fn test_no_proxy_empty_when_no_non_credential_hosts() {
        let (shutdown_tx, _) = tokio::sync::watch::channel(false);
        let handle = ProxyHandle {
            port: 12345,
            token: Zeroizing::new("test_token".to_string()),
            audit_log: audit::new_audit_log(),
            shutdown_tx,
            loaded_routes: std::collections::HashSet::new(),
            no_proxy_hosts: Vec::new(),
        };

        let vars = handle.env_vars();
        let no_proxy = vars.iter().find(|(k, _)| k == "NO_PROXY").unwrap();
        assert_eq!(
            no_proxy.1, "localhost,127.0.0.1",
            "NO_PROXY should only contain loopback when no bypass hosts"
        );
    }
}