mechanics_http_server/
alt_svc.rs

1//! `Alt-Svc` response middleware for advertising the QUIC listener.
2
3use std::future::Future;
4use std::pin::Pin;
5use std::task::{Context, Poll};
6
7use http::header::{ALT_SVC, HeaderValue};
8use http::{Request, Response};
9use tower::{Layer, Service};
10
11/// Build an [`AltSvcLayer`] for `h3=":<port>"; ma=<max-age>`.
12pub fn alt_svc_layer(h3_port: u16, max_age_secs: u64) -> AltSvcLayer {
13    AltSvcLayer::new(h3_port, max_age_secs)
14}
15
16/// Tower layer that inserts an HTTP/3 `Alt-Svc` response header.
17#[derive(Clone, Debug, Eq, PartialEq)]
18pub struct AltSvcLayer {
19    header_value: HeaderValue,
20}
21
22impl AltSvcLayer {
23    /// Build an `AltSvcLayer` for `h3=":<port>"; ma=<max-age>`.
24    pub fn new(h3_port: u16, max_age_secs: u64) -> Self {
25        let value = format!("h3=\":{h3_port}\"; ma={max_age_secs}");
26        Self {
27            header_value: HeaderValue::from_str(&value)
28                .unwrap_or_else(|_| HeaderValue::from_static("h3=\":443\"; ma=86400")),
29        }
30    }
31}
32
33impl<S> Layer<S> for AltSvcLayer {
34    type Service = AltSvcService<S>;
35
36    fn layer(&self, inner: S) -> Self::Service {
37        AltSvcService {
38            inner,
39            header_value: self.header_value.clone(),
40        }
41    }
42}
43
44/// Service produced by [`AltSvcLayer`].
45#[derive(Clone, Debug)]
46pub struct AltSvcService<S> {
47    inner: S,
48    header_value: HeaderValue,
49}
50
51impl<S, ReqBody, ResBody> Service<Request<ReqBody>> for AltSvcService<S>
52where
53    S: Service<Request<ReqBody>, Response = Response<ResBody>>,
54    S::Future: Send + 'static,
55{
56    type Response = Response<ResBody>;
57    type Error = S::Error;
58    type Future =
59        Pin<Box<dyn Future<Output = std::result::Result<Self::Response, Self::Error>> + Send>>;
60
61    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<std::result::Result<(), Self::Error>> {
62        self.inner.poll_ready(cx)
63    }
64
65    fn call(&mut self, req: Request<ReqBody>) -> Self::Future {
66        let future = self.inner.call(req);
67        let header_value = self.header_value.clone();
68        Box::pin(async move {
69            let mut response = future.await?;
70            response.headers_mut().insert(ALT_SVC, header_value);
71            Ok(response)
72        })
73    }
74}
mechanics_http_server/alt_svc.rs

mechanics_http_server/
alt_svc.rs
