tonic_web/
client.rs

1use http::header::CONTENT_TYPE;
2use http::{Request, Response, Version};
3use pin_project::pin_project;
4use std::fmt;
5use std::future::Future;
6use std::pin::Pin;
7use std::task::{ready, Context, Poll};
8use tower_layer::Layer;
9use tower_service::Service;
10use tracing::debug;
11
12use crate::call::content_types::GRPC_WEB;
13use crate::call::GrpcWebCall;
14
15/// Layer implementing the grpc-web protocol for clients.
16#[derive(Debug, Default, Clone)]
17pub struct GrpcWebClientLayer {
18    _priv: (),
19}
20
21impl GrpcWebClientLayer {
22    /// Create a new grpc-web for clients layer.
23    pub fn new() -> GrpcWebClientLayer {
24        Self::default()
25    }
26}
27
28impl<S> Layer<S> for GrpcWebClientLayer {
29    type Service = GrpcWebClientService<S>;
30
31    fn layer(&self, inner: S) -> Self::Service {
32        GrpcWebClientService::new(inner)
33    }
34}
35
36/// A [`Service`] that wraps some inner http service that will
37/// coerce requests coming from [`tonic::client::Grpc`] into proper
38/// `grpc-web` requests.
39#[derive(Debug, Clone)]
40pub struct GrpcWebClientService<S> {
41    inner: S,
42}
43
44impl<S> GrpcWebClientService<S> {
45    /// Create a new grpc-web for clients service.
46    pub fn new(inner: S) -> Self {
47        Self { inner }
48    }
49}
50
51impl<S, B1, B2> Service<Request<B1>> for GrpcWebClientService<S>
52where
53    S: Service<Request<GrpcWebCall<B1>>, Response = Response<B2>>,
54{
55    type Response = Response<GrpcWebCall<B2>>;
56    type Error = S::Error;
57    type Future = ResponseFuture<S::Future>;
58
59    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
60        self.inner.poll_ready(cx)
61    }
62
63    fn call(&mut self, mut req: Request<B1>) -> Self::Future {
64        if req.version() == Version::HTTP_2 {
65            debug!("coercing HTTP2 request to HTTP1.1");
66
67            *req.version_mut() = Version::HTTP_11;
68        }
69
70        req.headers_mut()
71            .insert(CONTENT_TYPE, GRPC_WEB.try_into().unwrap());
72
73        let req = req.map(GrpcWebCall::client_request);
74
75        let fut = self.inner.call(req);
76
77        ResponseFuture { inner: fut }
78    }
79}
80
81/// Response future for the [`GrpcWebService`](crate::GrpcWebService).
82#[pin_project]
83#[must_use = "futures do nothing unless polled"]
84pub struct ResponseFuture<F> {
85    #[pin]
86    inner: F,
87}
88
89impl<F, B, E> Future for ResponseFuture<F>
90where
91    F: Future<Output = Result<Response<B>, E>>,
92{
93    type Output = Result<Response<GrpcWebCall<B>>, E>;
94
95    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
96        let res = ready!(self.project().inner.poll(cx));
97
98        Poll::Ready(res.map(|r| r.map(GrpcWebCall::client_response)))
99    }
100}
101
102impl<F> fmt::Debug for ResponseFuture<F> {
103    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
104        f.debug_struct("ResponseFuture").finish()
105    }
106}
tonic_web/client.rs

tonic_web/
client.rs
