feat: altSvcHijackResponseWriter now optionally implements http.Hijacker to support WebSockets

extras/masq/server.go

@@ -1,8 +1,10 @@
 package masq
 
 import (
+	"bufio"
 	"crypto/tls"
 	"fmt"
+	"net"
 	"net/http"
 )
 
@@ -28,10 +30,7 @@ func (s *MasqTCPServer) ListenAndServeHTTP(addr string) error {
 			}
 			return
 		}
-		s.Handler.ServeHTTP(&altSvcHijackResponseWriter{
-			Port:           s.QUICPort,
-			ResponseWriter: w,
-		}, r)
+		s.Handler.ServeHTTP(newAltSvcHijackResponseWriter(w, s.QUICPort), r)
 	}))
 }
 
@@ -39,16 +38,15 @@ func (s *MasqTCPServer) ListenAndServeHTTPS(addr string) error {
 	server := &http.Server{
 		Addr: addr,
 		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			s.Handler.ServeHTTP(&altSvcHijackResponseWriter{
-				Port:           s.QUICPort,
-				ResponseWriter: w,
-			}, r)
+			s.Handler.ServeHTTP(newAltSvcHijackResponseWriter(w, s.QUICPort), r)
 		}),
 		TLSConfig: s.TLSConfig,
 	}
 	return server.ListenAndServeTLS("", "")
 }
 
+var _ http.ResponseWriter = (*altSvcHijackResponseWriter)(nil)
+
 // altSvcHijackResponseWriter makes sure that the Alt-Svc's port
 // is always set with our own value, no matter what the handler sets.
 type altSvcHijackResponseWriter struct {
@@ -60,3 +58,30 @@ func (w *altSvcHijackResponseWriter) WriteHeader(statusCode int) {
 	w.Header().Set("Alt-Svc", fmt.Sprintf(`h3=":%d"; ma=2592000`, w.Port))
 	w.ResponseWriter.WriteHeader(statusCode)
 }
+
+var _ http.Hijacker = (*altSvcHijackResponseWriterHijacker)(nil)
+
+// altSvcHijackResponseWriterHijacker is a wrapper around altSvcHijackResponseWriter
+// that also implements http.Hijacker. This is needed for WebSocket support.
+type altSvcHijackResponseWriterHijacker struct {
+	altSvcHijackResponseWriter
+}
+
+func (w *altSvcHijackResponseWriterHijacker) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	return w.ResponseWriter.(http.Hijacker).Hijack()
+}
+
+func newAltSvcHijackResponseWriter(w http.ResponseWriter, port int) http.ResponseWriter {
+	if _, ok := w.(http.Hijacker); ok {
+		return &altSvcHijackResponseWriterHijacker{
+			altSvcHijackResponseWriter: altSvcHijackResponseWriter{
+				Port:           port,
+				ResponseWriter: w,
+			},
+		}
+	}
+	return &altSvcHijackResponseWriter{
+		Port:           port,
+		ResponseWriter: w,
+	}
+}