Use a mutex instead of sync.Map in RouteUDP.

internal/client/piper.go

@@ -18,7 +18,8 @@ func RouteUDP(bindFunc func() (*net.UDPConn, error), streamTimeout time.Duration
 		log.Fatal(err)
 	}
 
-	var streams sync.Map
+	streams := make(map[string]*mux.Stream)
+	var streamsMutex sync.Mutex
 
 	data := make([]byte, 8192)
 	for {
@@ -32,15 +33,14 @@ func RouteUDP(bindFunc func() (*net.UDPConn, error), streamTimeout time.Duration
 			sesh = newSeshFunc()
 		}
 
-		var stream *mux.Stream
-		streamObj, ok := streams.Load(addr.String())
+		streamsMutex.Lock()
+		stream, ok := streams[addr.String()]
 		if !ok {
 			if singleplex {
 				sesh = newSeshFunc()
 			}
 
 			stream, err = sesh.OpenStream()
-			streamObj = stream
 			if err != nil {
 				if singleplex {
 					sesh.Close()
@@ -50,7 +50,9 @@ func RouteUDP(bindFunc func() (*net.UDPConn, error), streamTimeout time.Duration
 			}
 			_ = stream.SetReadDeadline(time.Now().Add(streamTimeout))
 
-			streams.Store(addr.String(), stream)
+			streams[addr.String()] = stream
+			streamsMutex.Unlock()
+
 			proxyAddr := addr
 			go func(stream *mux.Stream, localConn *net.UDPConn) {
 				buf := make([]byte, 8192)
@@ -58,7 +60,9 @@ func RouteUDP(bindFunc func() (*net.UDPConn, error), streamTimeout time.Duration
 					n, err := stream.Read(buf)
 					if err != nil {
 						log.Tracef("copying stream to proxy client: %v", err)
-						streams.Delete(addr.String())
+						streamsMutex.Lock()
+						delete(streams, addr.String())
+						streamsMutex.Unlock()
 						stream.Close()
 						return
 					}
@@ -67,19 +71,24 @@ func RouteUDP(bindFunc func() (*net.UDPConn, error), streamTimeout time.Duration
 					_, err = localConn.WriteTo(buf[:n], proxyAddr)
 					if err != nil {
 						log.Tracef("copying stream to proxy client: %v", err)
-						streams.Delete(addr.String())
+						streamsMutex.Lock()
+						delete(streams, addr.String())
+						streamsMutex.Unlock()
 						stream.Close()
 						return
 					}
 				}
 			}(stream, localConn)
+		} else {
+			streamsMutex.Unlock()
 		}
 
-		stream = streamObj.(*mux.Stream)
 		_, err = stream.Write(data[:i])
 		if err != nil {
 			log.Tracef("copying proxy client to stream: %v", err)
-			streams.Delete(addr.String())
+			streamsMutex.Lock()
+			delete(streams, addr.String())
+			streamsMutex.Unlock()
 			stream.Close()
 			continue
 		}