Don't remove the Sec-WebSocket-Key header in WebSocketUpgrade

Fixes #1971

Author: davidpdrsn

axum/CHANGELOG.md

@@ -52,6 +52,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   use `axum::serve(listener, service)` or hyper/hyper-util for more configuration options ([#1868])
 - **breaking:** Only inherit fallbacks for routers nested with `Router::nest`.
   Routers nested with `Router::nest_service` will no longer inherit fallbacks ([#1956])
+- **fixed:** Don't remove the `Sec-WebSocket-Key` header in `WebSocketUpgrade`
 
 [#1664]: https://github.com/tokio-rs/axum/pull/1664
 [#1751]: https://github.com/tokio-rs/axum/pull/1751

axum/src/extract/ws.rs

@@ -381,8 +381,9 @@ where
 
         let sec_websocket_key = parts
             .headers
-            .remove(header::SEC_WEBSOCKET_KEY)
-            .ok_or(WebSocketKeyHeaderMissing)?;
+            .get(header::SEC_WEBSOCKET_KEY)
+            .ok_or(WebSocketKeyHeaderMissing)?
+            .clone();
 
         let on_upgrade = parts
             .extensions