webrtc: fix connection in case of high latency

When latency is high, one side of the peer connection switched to the
"connected" state before the other one, and then closed the WebSocket
connection since it's useless after the peer connection has been
established. This caused the other side of the connection to detect a
WebSocket error and to exit.

The WebSocket connection must remain open, otherwise the
"connected" state is not set by both parts.

internal/core/webrtc_conn.go

@@ -30,6 +30,10 @@ import (
 	"github.com/aler9/rtsp-simple-server/internal/logger"
 )
 
+const (
+	handshakeDeadline = 10 * time.Second
+)
+
 type webRTCTrack struct {
 	media       *media.Media
 	format      format.Format
@@ -205,8 +209,8 @@ func (c *webRTCConn) runInner(ctx context.Context) error {
 	}
 
 	// maximum deadline to complete the handshake
-	c.wsconn.SetReadDeadline(time.Now().Add(10 * time.Second))
-	c.wsconn.SetWriteDeadline(time.Now().Add(10 * time.Second))
+	c.wsconn.SetReadDeadline(time.Now().Add(handshakeDeadline))
+	c.wsconn.SetWriteDeadline(time.Now().Add(handshakeDeadline))
 
 	err = c.writeICEServers(c.genICEServers())
 	if err != nil {
@@ -340,8 +344,11 @@ outer:
 		}
 	}
 
+	// do NOT close the WebSocket connection
+	// in order to allow the other side of the connection
+	// o switch to the "connected" state before WebSocket is closed.
+
 	c.log(logger.Info, "peer connection established")
-	c.wsconn.Close()
 
 	ringBuffer, _ := ringbuffer.New(uint64(c.readBufferCount))
 	defer ringBuffer.Close()

internal/core/webrtc_index.html

@@ -81,9 +81,11 @@ class Receiver {
             case "connected":
                 this.pc.onicecandidate = undefined;
                 this.ws.onmessage = undefined;
+                this.ws.onerror = undefined
                 this.ws.onclose = undefined;
-                this.ws.close();
-                this.ws = null;
+                // do not close the WebSocket connection
+                // in order to allow the other side of the connection
+                // to switch to the "connected" state before WebSocket is closed.
                 break;
 
             case "disconnected":