HTTP content coding for request and response bodies.

Currently supports:

• gzip (RFC 1952)
• deflate, in its zlib-wrapped form (RFC 1950), like browsers
• brotli (RFC 7932)
• zstd (RFC 8878)

Requests

• Use encode or encode_stream to compress a request body and declare it, together.

use http::HeaderMap;
use web_faith_encoding::{Coding, request::encode};

# async fn example() {
let mut headers = HeaderMap::new();
let body = b"the quick brown fox".repeat(8);

let compressed = encode(&mut headers, &body, Coding::Gzip).await.expect("gzip compresses");
assert!(compressed.len() < body.len());
assert_eq!(headers["content-encoding"], "gzip");
# }

To drive the halves separately, compress_buffer and compress_stream do the body, and [ContentEncoding::layer] with to_header_value does the header.

Responses

• Use AcceptEncoding to parse the advertised supported coding set from the request.
• Use decode to take one layer off a response: it decodes the body and updates the headers together.
• A body encoded more than once takes one call per layer.

use std::pin::Pin;

use bytes::Bytes;
use futures::TryStreamExt as _;
use http::{HeaderMap, HeaderValue};
use web_faith_encoding::{
    Coding,
    request::encode,
    response::{AcceptEncoding, ByteStream, decode},
};

# async fn example() {
let mut request = HeaderMap::new();
request.insert("accept-encoding", HeaderValue::from_static("gzip, br;q=0.5"));
let accept = AcceptEncoding::from(&request);

// A body gzipped over a coding the caller applied themselves.
let mut response = HeaderMap::new();
response.insert("content-encoding", HeaderValue::from_static("custom-thing"));
let gzipped = encode(&mut response, b"pretend this is custom-thing", Coding::Gzip)
    .await
    .expect("gzip compresses");
assert_eq!(response["content-encoding"], "custom-thing, gzip");

let body: Pin<Box<ByteStream>> =
    Box::pin(futures::stream::once(async move { Ok(Bytes::from(gzipped)) }));
let decoded: Vec<u8> = decode(&mut response, body, &accept)
    .try_fold(Vec::new(), |mut acc, chunk| async move {
        acc.extend_from_slice(&chunk);
        Ok(acc)
    })
    .await
    .expect("the gzip decodes");

// gzip came off, and the header names what is still under it.
assert_eq!(decoded, b"pretend this is custom-thing");
assert_eq!(response["content-encoding"], "custom-thing");
# }