I/O HTTP

HTTP client library for Rust

This library is composed of 3 feature-gated layers:

Low-level I/O-free coroutines: no_std-compatible state machines containing the whole HTTP logic, usable anywhere
Mid-level light client: a standard, blocking client wrapping a stream you opened yourself
High-level full client: the light client plus TCP connections and TLS negotiations handled for you

Features

I/O-free coroutines: no_std state machines with no sockets and no async runtime, resumable from any blocking, async or in-memory test harness.
HTTP/1.0 and HTTP/1.1: send a request and receive its response, with fixed-length, chunked and read-to-EOF body strategies; redirects are surfaced to the caller, never followed silently.
Streaming: decode a long-lived chunked response one chunk at a time and consume server-sent events as they arrive.
Authentication helpers: build and parse basic and bearer authorization values, with credentials redacted from debug output and logs.
Well-known discovery: probe the reserved well-known location of a service and surface where it redirects.
Light standard, blocking client wrapping a stream you opened yourself
Full standard, blocking client with TLS support:
- Rustls with ring crypto (requires rustls-ring feature, enabled by default)
- Rustls with aws crypto (requires rustls-aws feature)
- Native TLS (requires native-tls feature)

[!TIP] I/O HTTP is written in Rust and uses cargo features to gate backend support. The default feature set is declared in Cargo.toml or on docs.rs.

RFC	What is covered
1945	HTTP/1.0: send a request and receive its response, connections closing after each exchange by default
6750	Bearer authentication: carry an OAuth 2.0 access token in the authorization header
7617	Basic authentication: carry a base64-encoded username and password pair in the authorization header
8615	Well-known discovery: probe the reserved well-known path of an origin and surface the redirect target
9110	HTTP semantics: the version-agnostic request, response, status code and authentication challenge model shared by every wire format
9112	HTTP/1.1: send a request and receive its response, including chunked bodies, both whole and streamed
SSE	Server-sent events (WHATWG HTML Living Standard): decode an event stream one event at a time

The whole API is documented on docs.rs, including runnable snippets for every coroutine and client.

Complete runnable programs live in ./examples; the tests also demonstrate real usage.

This project is licensed under either of:

Special thanks to the NLnet foundation and the European Commission that have been financially supporting the project for years:

This program is part of Pimalaya, free software funded entirely by grants and donations. If you find it useful, consider sponsoring its development: