genmeta_proxy/
h3_forward.rs

1use dhttp::{
2    endpoint::Endpoint,
3    h3x::dhttp::message::{MessageStreamError, MessageWriter},
4};
5use http::uri::{self, Uri};
6use hyper::{
7    Request, Response,
8    body::{Body, Incoming},
9    header,
10};
11use snafu::ResultExt;
12
13use crate::Error;
14
15/// Hop-by-hop headers that MUST NOT be forwarded to HTTP/3 (RFC 9110 §7.6.1,
16/// RFC 9114 §4.2).
17const HOP_BY_HOP_HEADERS: &[header::HeaderName] = &[
18    header::CONNECTION,
19    header::TRANSFER_ENCODING,
20    header::TE,
21    header::UPGRADE,
22    header::HOST,
23    // keep-alive and proxy-connection are not constants in http crate
24];
25
26/// Rewrite an HTTP/1.1 proxy request for forwarding over HTTP/3.
27///
28/// - Changes the URI scheme from `http` to `https` (HTTP/3 mandates TLS).
29/// - Strips hop-by-hop headers that are illegal in HTTP/3.
30fn rewrite_request_for_h3(mut req: Request<Incoming>) -> Request<Incoming> {
31    // Rewrite URI scheme: http → https
32    let uri = req.uri().clone();
33    let mut parts = uri.into_parts();
34    parts.scheme = Some(uri::Scheme::HTTPS);
35    if let Ok(new_uri) = Uri::from_parts(parts) {
36        *req.uri_mut() = new_uri;
37    }
38
39    // Strip hop-by-hop headers
40    let headers = req.headers_mut();
41    for name in HOP_BY_HOP_HEADERS {
42        headers.remove(name);
43    }
44    headers.remove("proxy-connection");
45    headers.remove("keep-alive");
46
47    req
48}
49
50/// Close the write stream after request is fully sent.
51///
52/// Failure to close is non-fatal — the response may already be readable.
53async fn close_write_stream(mut write_stream: MessageWriter) {
54    if let Err(e) = write_stream.close().await {
55        tracing::warn!(error = %snafu::Report::from_error(&e), "failed to close h3 request stream");
56    }
57}
58
59/// Forward a plain HTTP request to a DHTTP identity domain via DHTTP/3.
60pub async fn forward_h3(
61    req: Request<Incoming>,
62    client: &Endpoint,
63) -> Result<Response<impl Body<Data = bytes::Bytes, Error = MessageStreamError> + use<>>, Error> {
64    let authority = req
65        .uri()
66        .authority()
67        .ok_or_else(|| {
68            <Error as snafu::FromString>::without_source(
69                "missing authority in dhttp/3 request uri".to_string(),
70            )
71        })?
72        .clone();
73
74    let connection = client
75        .connect(authority.clone())
76        .await
77        .whatever_context::<_, Error>(format!(
78            "failed to connect to dhttp/3 server `{authority}`"
79        ))?;
80
81    let (mut read_stream, mut write_stream) = connection
82        .initial_message_stream()
83        .await
84        .whatever_context::<_, Error>("failed to open h3 message stream")?;
85
86    let req = rewrite_request_for_h3(req);
87
88    write_stream
89        .send_hyper_request(req)
90        .await
91        .whatever_context::<_, Error>("failed to send h3 request")?;
92
93    // Read response headers and close write stream concurrently.
94    // tokio::join! polls the first future first (biased toward response).
95    let (response_result, _) = tokio::join!(
96        async {
97            let mut parts = read_stream
98                .read_hyper_response_parts()
99                .await
100                .whatever_context::<_, Error>("failed to read h3 response")?;
101            while parts.status.is_informational() {
102                tracing::debug!(status = %parts.status, "skipping informational response");
103                parts = read_stream
104                    .read_hyper_response_parts()
105                    .await
106                    .whatever_context::<_, Error>("failed to read h3 response")?;
107            }
108            Ok::<_, Error>(parts)
109        },
110        close_write_stream(write_stream),
111    );
112
113    let response_parts = response_result?;
114    let body = read_stream.into_hyper_body();
115    let mut resp = Response::from_parts(response_parts, body);
116    // Rewrite version: HTTP/3 responses cannot be sent over an HTTP/1.1
117    // connection — hyper's HTTP/1 codec panics on unknown versions.
118    *resp.version_mut() = http::Version::HTTP_11;
119    Ok(resp)
120}
genmeta_proxy/h3_forward.rs

genmeta_proxy/
h3_forward.rs
