chore: Add voip connection tester.

lib/matrix.dart

@@ -32,6 +32,7 @@ export 'src/voip/call.dart';
 export 'src/voip/group_call.dart';
 export 'src/voip/voip.dart';
 export 'src/voip/voip_content.dart';
+export 'src/voip/conn_tester.dart';
 export 'src/voip/utils.dart';
 export 'src/room.dart';
 export 'src/timeline.dart';

lib/src/voip/conn_tester.dart

@@ -0,0 +1,113 @@
+import 'dart:async';
+
+import 'package:webrtc_interface/webrtc_interface.dart';
+
+import 'package:matrix/matrix.dart';
+
+class ConnectionTester {
+  Client client;
+  WebRTCDelegate delegate;
+  RTCPeerConnection? pc1, pc2;
+  ConnectionTester(this.client, this.delegate);
+  TurnServerCredentials? _turnServerCredentials;
+
+  Future<bool> verifyTurnServer() async {
+    final iceServers = await getIceSevers();
+    final configuration = <String, dynamic>{
+      'iceServers': iceServers,
+      'sdpSemantics': 'unified-plan',
+      'iceCandidatePoolSize': 1,
+      'iceTransportPolicy': 'relay'
+    };
+    pc1 = await delegate.createPeerConnection(configuration);
+    pc2 = await delegate.createPeerConnection(configuration);
+
+    pc1!.onIceCandidate = (candidate) {
+      if (candidate.candidate!.contains('relay')) {
+        pc2!.addCandidate(candidate);
+      }
+    };
+    pc2!.onIceCandidate = (candidate) {
+      if (candidate.candidate!.contains('relay')) {
+        pc1!.addCandidate(candidate);
+      }
+    };
+
+    await pc1!.createDataChannel('conn-tester', RTCDataChannelInit());
+
+    final offer = await pc1!.createOffer();
+
+    await pc2!.setRemoteDescription(offer);
+    final answer = await pc2!.createAnswer();
+
+    await pc1!.setLocalDescription(offer);
+    await pc2!.setLocalDescription(answer);
+
+    await pc1!.setRemoteDescription(answer);
+
+    void dispose() {
+      pc1!.close();
+      pc1!.dispose();
+      pc2!.close();
+      pc2!.dispose();
+    }
+
+    bool connected = false;
+    try {
+      await waitUntilAsync(() async {
+        if (pc1!.connectionState ==
+                RTCPeerConnectionState.RTCPeerConnectionStateConnected &&
+            pc2!.connectionState ==
+                RTCPeerConnectionState.RTCPeerConnectionStateConnected) {
+          connected = true;
+          return true;
+        }
+        return false;
+      });
+    } catch (e) {
+      Logs().e('[VOIP] ConnectionTester Error while testing TURN server: $e');
+    }
+
+    dispose();
+    return connected;
+  }
+
+  Future<int> waitUntilAsync(Future<bool> Function() test,
+      {final int maxIterations = 1000,
+      final Duration step = const Duration(milliseconds: 10)}) async {
+    int iterations = 0;
+    for (; iterations < maxIterations; iterations++) {
+      await Future.delayed(step);
+      if (await test()) {
+        break;
+      }
+    }
+    if (iterations >= maxIterations) {
+      throw TimeoutException(
+          'Condition not reached within ${iterations * step.inMilliseconds}ms');
+    }
+    return iterations;
+  }
+
+  Future<List<Map<String, dynamic>>> getIceSevers() async {
+    if (_turnServerCredentials == null) {
+      try {
+        _turnServerCredentials = await client.getTurnServer();
+      } catch (e) {
+        Logs().v('[VOIP] getTurnServerCredentials error => ${e.toString()}');
+      }
+    }
+
+    if (_turnServerCredentials == null) {
+      return [];
+    }
+
+    return [
+      {
+        'username': _turnServerCredentials!.username,
+        'credential': _turnServerCredentials!.password,
+        'url': _turnServerCredentials!.uris[0]
+      }
+    ];
+  }
+}