Add protocol field to WebSocket (#1022)

* Add protocol field to WebSocket

Signed-off-by: Matteo Joliveau <matteojoliveau@gmail.com>

* Use HeaderValue instead of String

Signed-off-by: Matteo Joliveau <matteojoliveau@gmail.com>

* Update axum/src/extract/ws.rs

Co-authored-by: Jonas Platte <jplatte+git@posteo.de>

* Update changelog

Co-authored-by: David Pedersen <david.pdrsn@gmail.com>
Co-authored-by: Jonas Platte <jplatte+git@posteo.de>

axum/CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 # Unreleased
 
-- None.
+- **added:** Add `WebSocket::protocol` to return the selected WebSocket subprotocol, if there is one. ([#1022])
+
+[#1022]: https://github.com/tokio-rs/axum/pull/1022
 
 # 0.5.5 (10. May, 2022)
 

axum/src/extract/ws.rs

@@ -207,12 +207,17 @@ impl WebSocketUpgrade {
         let on_upgrade = self.on_upgrade;
         let config = self.config;
 
+        let protocol = self.protocol.clone();
+
         tokio::spawn(async move {
             let upgraded = on_upgrade.await.expect("connection upgrade failed");
             let socket =
                 WebSocketStream::from_raw_socket(upgraded, protocol::Role::Server, Some(config))
                     .await;
-            let socket = WebSocket { inner: socket };
+            let socket = WebSocket {
+                inner: socket,
+                protocol,
+            };
             callback(socket).await;
         });
 
@@ -309,6 +314,7 @@ fn header_contains<B>(req: &RequestParts<B>, key: HeaderName, value: &'static st
 #[derive(Debug)]
 pub struct WebSocket {
     inner: WebSocketStream<Upgraded>,
+    protocol: Option<HeaderValue>,
 }
 
 impl WebSocket {
@@ -331,6 +337,11 @@ impl WebSocket {
     pub async fn close(mut self) -> Result<(), Error> {
         self.inner.close(None).await.map_err(Error::new)
     }
+
+    /// Return the selected WebSocket subprotocol, if one has been chosen.
+    pub fn protocol(&self) -> Option<&HeaderValue> {
+        self.protocol.as_ref()
+    }
 }
 
 impl Stream for WebSocket {