httpsd

A pure-Rust HTTP server (HTTP/1.1, HTTP/2, and HTTP/3) with a sans-I/O core and pluggable runtimes.

Use it as a library — drop in your own handler and pick the runtime that fits (blocking thread pool, tokio, or mio) — or as a command-line server that serves a directory or a TOML config file.

• Sans-I/O protocol core. proto::H1Conn turns bytes into Requests and serializes Responses back into bytes. It owns no socket, so it is trivially testable and reusable across every runtime.
• HTTP/1.1, HTTP/2, and HTTP/3. One synchronous Handler serves all three. HTTP/2 is negotiated via ALPN on the TLS server; HTTP/3 runs over QUIC/UDP.
• TLS & QUIC via purecrypto. HTTPS is built on purecrypto's own sans-I/O TLS 1.2/1.3 engine and HTTP/3 on its QUIC stack — no OpenSSL, no C.
• Compression via compcol. gzip/deflate response compression, plus HPACK (HTTP/2) and QPACK (HTTP/3) header coding.
• Automatic certificates (ACME). On-demand issuance keyed on SNI (Let's Encrypt or any ACME CA), TLS-ALPN-01 + HTTP-01 challenges, on-disk persistence and renewal. HTTP is redirected to HTTPS by default; bare-IP requests are redirected to a resolvable g-dns.net host.
• No mandatory async runtime. The default build is a blocking thread pool; tokio and mio are opt-in.

Quick start (CLI)

# Serve the current directory over HTTP on 127.0.0.1:8080
httpsd

# Serve a specific directory on a chosen address
httpsd ./public -l 0.0.0.0:8080

# HTTPS with a real certificate
httpsd ./public -l 0.0.0.0:8443 --tls-cert cert.pem --tls-key key.pem

# HTTPS with an ephemeral self-signed cert (development)
httpsd ./public -l 127.0.0.1:8443 --self-signed

# Also serve HTTP/3 over QUIC/UDP on the same port (requires TLS)
httpsd ./public -l 127.0.0.1:8443 --self-signed --http3

# Automatic HTTPS with Let's Encrypt (issues certs on demand, per SNI)
httpsd /srv/www -l 0.0.0.0:443 --http 0.0.0.0:80 \
    --acme-accept-tos --acme-email you@example.com

# Run from a config file (see samples/config.toml)
httpsd -c config.toml

HTTP/2 is negotiated automatically over HTTPS (ALPN h2); clients that don't support it fall back to HTTP/1.1. HTTP/3 is served on UDP by default whenever a TLS certificate is configured (use --no-http3 to disable), and advertised via Alt-Svc so browsers upgrade after the first request.

HTTP/3 currently requires a static certificate (--tls-cert/--self-signed). On-demand ACME certificates over HTTP/3 await a QUIC ClientHello/SNI peek in purecrypto (QUIC carries the same TLS SNI, but inside the encrypted Initial packet, so per-connection selection needs the engine to expose it pre-handshake — the h3 analog of the TCP path's peek_client_hello).

Run httpsd --help for all options.

Quick start (library)

use httpsd::{Server, Response, Request};

fn main() -> httpsd::Result<()> {
    Server::bind("127.0.0.1:8080")?
        .handler(|req: &Request| Response::text(format!("you asked for {}", req.path())))
        .run() // blocking thread-pool runtime
}

Serve static files:

use httpsd::Server;

Server::bind("0.0.0.0:8080")?
    .serve_dir("./public")
    .workers(8)
    .run()?;

Enable HTTPS:

use httpsd::{Server, tls::TlsAcceptor};

let acceptor = TlsAcceptor::from_pem_files("cert.pem", "key.pem")?;
Server::bind("0.0.0.0:8443")?
    .serve_dir("./public")
    .tls(acceptor)
    .run()?;

Choosing a runtime

The same Server drives any compiled-in runtime:

server.run()?;             // rt-threadpool: blocking accept loop + worker pool
server.run_tokio().await?; // rt-tokio: one async task per connection
server.run_mio()?;         // rt-mio: single-thread readiness event loop
server.run_h3()?;          // h3: QUIC/UDP event loop (HTTP/3)

The TCP runtimes serve HTTP/1.1 and (over TLS) HTTP/2; run_h3 serves HTTP/3 on UDP. To offer all three, run a TCP runtime and run_h3 on separate threads sharing the same TlsAcceptor.

A custom handler is just Fn(&Request) -> Response (or anything implementing Handler). Because the core is sans-I/O, one synchronous handler works identically under all three runtimes.

Automatic certificates (ACME)

With --acme-accept-tos (you accept the CA's terms of service) the server obtains certificates on demand: when a TLS ClientHello arrives for a host it has no certificate for, it issues one from the ACME CA and persists it, then serves it. Defaults chosen for safety:

• Challenges: TLS-ALPN-01 (all on 443) is tried first; HTTP-01 is a fallback when the --http listener is running.
• Storage: /var/lib/httpsd (FHS persistent state) → falls back to $XDG_DATA_HOME/httpsd when not root. Account key 0600, dirs 0700, atomic writes. (Never /run — tmpfs would cause re-issuance storms.)
• Loopback peers never trigger issuance — they get a self-signed cert.
• Scope: --host-whitelist a.com,b.com restricts which hosts may be issued; otherwise any SNI host is attempted. First issuance blocks the handshake (single-flight per host); renewal happens within 30 days of expiry.
• HTTPS-first: plain-HTTP requests are 308-redirected to HTTPS unless --allow-http. A request to a bare IP (or with no Host) is redirected to https://<base32(ip)>.g-dns.net/…, which resolves back to that IP so the follow-up request carries a real SNI host.
• HSTS: --hsts (optionally --hsts-max-age, --hsts-include-subdomains, --hsts-preload) sends Strict-Transport-Security on HTTPS responses only.

httpsd /srv/www -l 0.0.0.0:443 --http 0.0.0.0:80 \
    --acme-accept-tos --acme-email you@example.com --acme-staging

Drop --acme-staging for production Let's Encrypt; --acme-directory URL points at any other ACME CA. ACME currently runs under the thread-pool runtime.

Configuration file

listen = "0.0.0.0:8080"        # or ["127.0.0.1:8080", "[::1]:8080"]
root = "./public"              # document root for static file serving
server_name = "httpsd"
workers = 8

[tls]
cert = "cert.pem"              # PEM chain, leaf first
key  = "key.pem"               # PKCS#8 / PKCS#1 RSA / SEC1 EC
# self_signed = ["localhost"]  # alternatively, generate an ephemeral cert

[compress]
enabled = true
min_size = 256

See samples/config.toml.

Feature flags

To use httpsd as a lean embeddable library — say, tokio HTTPS without the CLI:

[dependencies]
httpsd = { version = "0.1", default-features = false, features = ["rt-tokio", "tls", "compress"] }

Capabilities & limits

• HTTP/1.0 and HTTP/1.1 with persistent connections (keep-alive).
• HTTP/2 (RFC 9113) over TLS: HPACK, stream multiplexing, connection and per-stream flow control, SETTINGS/WINDOW_UPDATE/PING/RST_STREAM/GOAWAY.
• HTTP/3 (RFC 9114) over QUIC: control + QPACK streams, HEADERS/DATA framing, one connection per peer on a single UDP socket.
• Request bodies via Content-Length and chunked Transfer-Encoding (buffered), with configurable size limits.
• GET/HEAD static file serving with MIME detection, directory index.html, ETag/Last-Modified conditional requests, and single-range (206) support.
• Path-traversal protection (rejects .., canonicalizes against the root).
• Response compression negotiated from Accept-Encoding, skipping already-compressed media types and tiny bodies.
• Automatic ACME certificates (RFC 8555) with TLS-ALPN-01 (RFC 8737) and HTTP-01 challenges, on-disk persistence, and renewal; HTTP→HTTPS and bare-IP→g-dns.net redirects.

Verified against curl for HTTP/1.1, --http2, and --http3-only.

Out of scope for this version: streaming request/response bodies, HTTP/2 server push, QUIC connection migration, and async handler traits (handlers are synchronous by design). HTTP/3 demultiplexes connections by peer address.

License

MIT