fix: auto disconnect if lossy and reliable datachannel is not exist

Author: TzuHuanTai

src/args.h

@@ -47,9 +47,10 @@ struct Args {
     std::string ws_host = "192.168.4.21";
     std::string ws_token =
         "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9."
-        "eyJleHAiOjE3NzM4OTI2NjEsImlzcyI6IkFQSVduUVRzNHRtVVp2QSIsIm5iZiI6MTc0MjM1NjY2MSwic3ViIj"
-        "oiMTMxZGZjMzItNjRlMi00YjZiLTllZGEtZDdjYTU5NTNjYWJlIiwidmlkZW8iOnsicm9vbSI6ImRldmljZS0x"
-        "Iiwicm9vbUpvaW4iOnRydWV9fQ.ThQTHYd8CBR0t3epwcak6oaleeu760V96UF8GbOMUks";
+        "eyJleHAiOjE3NzQ3NDU2MzksImlzcyI6IkFQSVduUVRzNHRtVVp2QSIsIm5iZiI6MTc0MzIwOTYzOSwic3ViIjoiZj"
+        "JkNzRiOTUtMmYxNi00ODRiLTg3NjctYThjNWY3NzFlZWY2IiwidmlkZW8iOnsiY2FuUHVibGlzaCI6dHJ1ZSwiY2Fu"
+        "UHVibGlzaERhdGEiOnRydWUsImNhblN1YnNjcmliZSI6ZmFsc2UsInJvb20iOiJkZXZpY2UtMSIsInJvb21Kb2luIj"
+        "p0cnVlfX0.o7e-gjkqfMpeDjATwaWWLKUWPa8RlaoIOcuw3p8FxQk";
 };
 
 #endif // ARGS_H_

src/conductor.cpp

@@ -125,6 +125,11 @@ rtc::scoped_refptr<RtcPeer> Conductor::CreatePeerConnection(PeerConfig config) {
 
     peer->SetPeer(result.MoveValue());
 
+    if (config.is_sfu_peer) {
+        peer->CreateDataChannel(ChannelLabel::Lossy);
+        peer->CreateDataChannel(ChannelLabel::Reliable);
+    }
+
     if (!config.is_publisher) {
         return peer;
     }

src/rtc_peer.cpp

@@ -61,28 +61,35 @@ void RtcPeer::SetPeer(rtc::scoped_refptr<webrtc::PeerConnectionInterface> peer)
 
 rtc::scoped_refptr<webrtc::PeerConnectionInterface> RtcPeer::GetPeer() { return peer_connection_; }
 
-void RtcPeer::CreateDataChannel() {
+void RtcPeer::CreateDataChannel(ChannelLabel label) {
     struct webrtc::DataChannelInit init;
     init.ordered = true;
     init.reliable = true;
-    init.id = 0;
-    auto result = peer_connection_->CreateDataChannelOrError("cmd_channel", &init);
+    init.id = static_cast<int>(label);
+
+    if (label == ChannelLabel::Lossy) {
+        init.maxRetransmits = 0;
+    }
+
+    auto result = peer_connection_->CreateDataChannelOrError(RtcPeer::LabelToString(label), &init);
 
     if (!result.ok()) {
         ERROR_PRINT("Failed to create data channel.");
         return;
     }
 
-    DEBUG_PRINT("The data channel is established successfully.");
-    data_channel_subject_ = std::make_shared<DataChannelSubject>();
-    data_channel_subject_->SetDataChannel(result.MoveValue());
+    if (label == ChannelLabel::Command) {
+        DEBUG_PRINT("The data channel is established successfully.");
+        data_channel_subject_ = std::make_shared<DataChannelSubject>();
+        data_channel_subject_->SetDataChannel(result.MoveValue());
 
-    auto conn_observer = data_channel_subject_->AsObservable(CommandType::CONNECT);
-    conn_observer->Subscribe([this](std::string message) {
-        if (message == "false") { // todo: use enum or so.
-            peer_connection_->Close();
-        }
-    });
+        auto conn_observer = data_channel_subject_->AsObservable(CommandType::CONNECT);
+        conn_observer->Subscribe([this](std::string message) {
+            if (message == "false") { // todo: use enum or so.
+                peer_connection_->Close();
+            }
+        });
+    }
 }
 
 std::string RtcPeer::RestartIce(std::string ice_ufrag, std::string ice_pwd) {

src/rtc_peer.h

@@ -12,6 +12,12 @@
 #include "common/logging.h"
 #include "data_channel_subject.h"
 
+enum ChannelLabel {
+    Command,
+    Lossy,
+    Reliable
+};
+
 struct PeerConfig : public webrtc::PeerConnectionInterface::RTCConfiguration {
     int timeout = 10;
     bool is_publisher = true;
@@ -91,7 +97,7 @@ class RtcPeer : public webrtc::PeerConnectionObserver,
     void SetSink(rtc::VideoSinkInterface<webrtc::VideoFrame> *video_sink_obj);
     void SetPeer(rtc::scoped_refptr<webrtc::PeerConnectionInterface> peer);
     rtc::scoped_refptr<webrtc::PeerConnectionInterface> GetPeer();
-    void CreateDataChannel();
+    void CreateDataChannel(ChannelLabel label = ChannelLabel::Command);
     std::string RestartIce(std::string ice_ufrag, std::string ice_pwd);
     void OnSnapshot(OnCommand func);
     void OnMetadata(OnCommand func);
@@ -103,6 +109,19 @@ class RtcPeer : public webrtc::PeerConnectionObserver,
     void SetRemoteIce(const std::string &sdp_mid, int sdp_mline_index,
                       const std::string &candidate) override;
 
+    static std::string LabelToString(ChannelLabel label) {
+        switch (label) {
+            case Command:
+                return "cmd_channel";
+            case Lossy:
+                return "_lossy";
+            case Reliable:
+                return "_reliable";
+            default:
+                return "unknown";
+        }
+    }
+
   private:
     void SubscribeCommandChannel(CommandType type, OnCommand func);