webrtc: fix detecting closure of some sessions (#4204) (#4212)

Author: aler9

internal/protocols/webrtc/peer_connection.go

@@ -301,6 +301,16 @@ func (co *PeerConnection) Start() error {
 			close(co.failed)
 
 		case webrtc.PeerConnectionStateClosed:
+			// "closed" can arrive before "failed" and without
+			// the Close() method being called at all.
+			// It happens when the other peer sends a termination
+			// message like a DTLS CloseNotify.
+			select {
+			case <-co.failed:
+			default:
+				close(co.failed)
+			}
+
 			close(co.done)
 		}
 	})

internal/servers/webrtc/publisher.js

@@ -372,7 +372,13 @@
         return;
       }
 
-      if (this.pc.connectionState === 'failed') {
+      // "closed" can arrive before "failed" and without
+      // the close() method being called at all.
+      // It happens when the other peer sends a termination
+      // message like a DTLS CloseNotify.
+      if (this.pc.connectionState === 'failed'
+        || this.pc.connectionState === 'closed'
+      ) {
         this.handleError('peer connection closed');
       } else if (this.pc.connectionState === 'connected') {
         if (this.conf.onConnected !== undefined) {

internal/servers/webrtc/reader.js

@@ -468,7 +468,13 @@
         return;
       }
 
-      if (this.pc.connectionState === 'failed') {
+      // "closed" can arrive before "failed" and without
+      // the close() method being called at all.
+      // It happens when the other peer sends a termination
+      // message like a DTLS CloseNotify.
+      if (this.pc.connectionState === 'failed'
+        || this.pc.connectionState === 'closed'
+      ) {
         this.handleError('peer connection closed');
       }
     };