handle remote candidates

Author: Mahad-10

app/src/main/java/io/xconn/wampwebrtc/Offerer.kt

@@ -1,6 +1,8 @@
 package io.xconn.wampwebrtc
 
 import android.content.Context
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.withTimeoutOrNull
 import org.webrtc.DataChannel
 import org.webrtc.IceCandidate
 import org.webrtc.MediaConstraints
@@ -30,6 +32,8 @@ class Offerer(
     var dataChannel: DataChannel? = null
     val peerConnectionFactory = PeerConnectionFactory.builder().createPeerConnectionFactory()
     private var assembler = MessageAssembler()
+    private var onDataChannelOpen: (() -> Unit)? = null
+    private var dataChannelTimeoutMillis: Long = 20000
 
     suspend fun createOffer(offerConfig: OfferConfig): SessionDescription? {
         val configuration = PeerConnection.RTCConfiguration(offerConfig.iceServers)
@@ -45,17 +49,7 @@ class Offerer(
                         }
                     }
 
-                    override fun onDataChannel(channel: DataChannel?) {
-                        channel?.registerObserver(
-                            object : DataChannel.Observer {
-                                override fun onMessage(buffer: DataChannel.Buffer?) {}
-
-                                override fun onBufferedAmountChange(p0: Long) {}
-
-                                override fun onStateChange() {}
-                            },
-                        )
-                    }
+                    override fun onDataChannel(channel: DataChannel?) {}
 
                     override fun onSignalingChange(p0: PeerConnection.SignalingState?) {}
 
@@ -83,6 +77,29 @@ class Offerer(
                 protocol = offerConfig.protocol
             }
         dataChannel = peerConnection?.createDataChannel("wamp", conf)
+        dataChannel?.registerObserver(
+            object : DataChannel.Observer {
+                override fun onStateChange() {
+                    if (dataChannel?.state() == DataChannel.State.OPEN) {
+                        onDataChannelOpen?.invoke()
+                    }
+                }
+
+                override fun onBufferedAmountChange(p0: Long) {}
+
+                override fun onMessage(buffer: DataChannel.Buffer?) {
+                    buffer?.data?.let {
+                        val data = ByteArray(it.remaining())
+                        it.get(data)
+
+                        val message = assembler.feed(data)
+                        if (message != null) {
+                            queue.put(message)
+                        }
+                    }
+                }
+            },
+        )
 
         return suspendCoroutine { continuation ->
             peerConnection?.createOffer(
@@ -115,32 +132,14 @@ class Offerer(
         }
     }
 
-    suspend fun waitForDataChannelOpen(): Unit =
-        suspendCoroutine { continuation ->
-            dataChannel?.registerObserver(
-                object : DataChannel.Observer {
-                    override fun onStateChange() {
-                        if (dataChannel?.state() == DataChannel.State.OPEN) {
-                            continuation.resume(Unit)
-                        }
-                    }
-
-                    override fun onBufferedAmountChange(p0: Long) {}
-
-                    override fun onMessage(buffer: DataChannel.Buffer?) {
-                        buffer?.data?.let {
-                            val data = ByteArray(it.remaining())
-                            it.get(data)
-
-                            val message = assembler.feed(data)
-                            if (message != null) {
-                                queue.put(message)
-                            }
-                        }
-                    }
-                },
-            )
-        }
+    suspend fun waitForDataChannelToOpen() {
+        withTimeoutOrNull(dataChannelTimeoutMillis) {
+            while (true) {
+                if (dataChannel?.state() == DataChannel.State.OPEN) return@withTimeoutOrNull
+                delay(100)
+            }
+        } ?: throw IllegalStateException("Data channel failed to open within $dataChannelTimeoutMillis milliseconds")
+    }
 
     fun setRemoteDescription(sessionDescription: SessionDescription) {
         peerConnection?.setRemoteDescription(

app/src/main/java/io/xconn/wampwebrtc/Types.kt

@@ -55,6 +55,7 @@ data class ClientConfig(
     val realm: String,
     val procedureWebRTCOffer: String,
     val topicAnswererOnCandidate: String,
+    val topicOffererOnCandidate: String,
     val serializer: Serializer,
     val subProtocol: String,
     val iceServers: List<IceServer>,

app/src/main/java/io/xconn/wampwebrtc/WebRTC.kt

@@ -1,9 +1,12 @@
 package io.xconn.wampwebrtc
 
 import android.content.Context
-import io.xconn.wampproto.serializers.CBORSerializer
 import io.xconn.xconn.Client
+import io.xconn.xconn.Event
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import org.json.JSONArray
 import org.json.JSONObject
@@ -16,8 +19,11 @@ class WebRTC(
     private val context: Context,
     private val queue: LinkedBlockingDeque<ByteArray>,
 ) {
+    private lateinit var offerer: Offerer
+    private val couroutineScope = CoroutineScope(Dispatchers.Default + Job())
+
     suspend fun connect(config: ClientConfig): WebRTCSession {
-        val client = Client(serializer = CBORSerializer())
+        val client = Client(serializer = config.serializer)
         val session = client.connect(config.url, config.realm)
 
         val requestID = UUID.randomUUID().toString()
@@ -31,7 +37,7 @@ class WebRTC(
             )
 
         val candidates: MutableList<IceCandidate> = mutableListOf()
-        val offerer =
+        offerer =
             Offerer(
                 context,
                 queue,
@@ -55,6 +61,10 @@ class WebRTC(
                 },
             )
 
+        couroutineScope.launch {
+            session.subscribe(config.topicOffererOnCandidate, ::candidateHandler).await()
+        }
+
         val offer = offerer.createOffer(offerConfig)
         Thread.sleep(200)
 
@@ -95,13 +105,48 @@ class WebRTC(
         val sdpString = descriptionMap.getString("sdp")
         val sdpType = descriptionMap.getString("type")
 
-        val remoteDescription =
-            SessionDescription(SessionDescription.Type.fromCanonicalForm(sdpType), sdpString)
+        val remoteDescription = SessionDescription(SessionDescription.Type.fromCanonicalForm(sdpType), sdpString)
 
         offerer.setRemoteDescription(remoteDescription)
 
-        offerer.waitForDataChannelOpen()
+        offerer.waitForDataChannelToOpen()
 
         return WebRTCSession(offerer.peerConnection!!, offerer.dataChannel!!)
     }
+
+    private fun candidateHandler(event: Event) {
+        if (event.args == null || event.args!!.size < 2) {
+            throw Exception("invalid arguments length")
+        }
+
+        val jsonString =
+            event.args?.get(1) as? String
+                ?: throw Exception("Invalid argument type: Second argument must be a JSON string")
+
+        val result =
+            try {
+                convertJsonToMap(jsonString)
+            } catch (e: Exception) {
+                throw Exception("Invalid JSON: Unable to parse JSON string")
+            }
+
+        val candidate =
+            result["candidate"] as? String
+                ?: throw Exception("Invalid candidate: 'candidate' field is missing or not a string")
+
+        val sdpMLineIndex =
+            result["sdpMLineIndex"] as? Int
+                ?: throw Exception("Invalid sdpMLineIndex: 'sdpMLineIndex' field is missing or not an integer")
+
+        val sdpMid =
+            result["sdpMid"] as? String
+                ?: throw Exception("Invalid sdpMid: 'sdpMid' field is missing or not a string")
+
+        try {
+            val iceCandidate = IceCandidate(sdpMid, sdpMLineIndex, candidate)
+            offerer.addIceCandidate(iceCandidate)
+        } catch (e: Exception) {
+            throw Exception("Failed to add ICE candidate: ${e.message}")
+        }
+    }
 }