Fix data channel open

Previously, the data channel object was not being created
for the peer that generates the offer/datachannel.

Included fixes:

* Send ACK after receiving DATA_CHANNEL_OPEN
* Pass and return uint16_t for all SIDs instead of int
* Calls new channel and on_open callbacks inside HandleAck
* Some formatting fixes

include/rtcdcpp/PeerConnection.hpp

@@ -161,7 +161,7 @@ class PeerConnection {
 
   // DataChannel message parsing
   void HandleNewDataChannel(ChunkPtr chunk, uint16_t sid);
-  void HandleDataChannelAck();
+  void HandleDataChannelAck(uint16_t sid);
   void HandleStringMessage(ChunkPtr chunk, uint16_t sid);
   void HandleBinaryMessage(ChunkPtr chunk, uint16_t sid);
 

include/rtcdcpp/SCTPWrapper.hpp

@@ -60,18 +60,19 @@ class SCTPWrapper {
   // Handle a decrypted SCTP packet
   void DTLSForSCTP(ChunkPtr chunk);
 
+  void SendACK();
   void CreateDCForSCTP(std::string label, std::string protocol="");
 
   dc_open_msg *data;
-  int sid;
+  uint16_t sid;
   std::string label;
   std::string protocol;
 
   dc_open_msg* GetDataChannelData();
-  int GetSid();
+  uint16_t GetSid();
   std::string GetProtocol();
   std::string GetLabel();
-  void SetDataChannelSID(int sid);
+  void SetDataChannelSID(uint16_t sid);
 
   // Send a message to the remote connection
   // Note, this will cause 1+ DTLSEncrypt callback calls

src/PeerConnection.cpp

@@ -210,11 +210,12 @@ void PeerConnection::OnSCTPMsgReceived(ChunkPtr chunk, uint16_t sid, uint32_t pp
   if (ppid == PPID_CONTROL) {
     SPDLOG_TRACE(logger, "Control PPID");
     if (chunk->Data()[0] == DC_TYPE_OPEN) {
+      logger->info("DC TYPE OPEN RECEIVED");
       SPDLOG_TRACE(logger, "New channel time!");
       HandleNewDataChannel(chunk, sid);
     } else if (chunk->Data()[0] == DC_TYPE_ACK) {
       SPDLOG_TRACE(logger, "DC ACK");
-      HandleDataChannelAck();
+      HandleDataChannelAck(sid);
     } else {
       SPDLOG_TRACE(logger, "Unknown msg_type for ppid control: {}", chunk->Data()[0]);
     }
@@ -257,29 +258,26 @@ void PeerConnection::HandleNewDataChannel(ChunkPtr chunk, uint16_t sid) {
   auto new_channel = std::make_shared<DataChannel>(this, sid, open_msg.chan_type, label, protocol);
 
   data_channels[sid] = new_channel;
-
+  this->sctp->SendACK();
   if (this->new_channel_cb) {
     this->new_channel_cb(new_channel);
   } else {
     logger->warn("No new channel callback, ignoring new channel");
   }
 }
 
-  void PeerConnection::HandleDataChannelAck() {
-  dc_open_msg* datachannel_data =   this->sctp->GetDataChannelData();
-  int sid =   this->sctp->GetSid();
-  std::string label = this->sctp->GetLabel();
-  std::string protocol = this->sctp->GetProtocol();  
-  // TODO: Support overriding an existing channel
-  auto new_channel = std::make_shared<DataChannel>(this, sid, datachannel_data->chan_type, label, protocol);
-
-  data_channels[sid] = new_channel;
-
+void PeerConnection::HandleDataChannelAck(uint16_t sid) {
+  auto new_channel = GetChannel(sid);
   if (this->new_channel_cb) {
     this->new_channel_cb(new_channel);
   } else {
     logger->warn("No new channel callback, ignoring new channel");
   }
+  if (!new_channel) {
+    logger->warn("Cannot find the datachannel for sid {}", sid);
+  } else {
+    new_channel->OnOpen();
+  }
 }  
 
 void PeerConnection::HandleStringMessage(ChunkPtr chunk, uint16_t sid) {
@@ -314,20 +312,25 @@ void PeerConnection::SendBinaryMsg(const uint8_t *data, int len, uint16_t sid) {
 }
 
 void PeerConnection::CreateDataChannel(std::string label, std::string protocol) {
-  int sid;
-  if(this->role == 0){
+  uint16_t sid;
+  if (this->role == 0) {
     sid = 0;
   } else {
     sid = 1;
   }
-  for(int i = sid; i < data_channels.size(); i = i + 2){
+  for (int i = sid; i < data_channels.size(); i = i + 2) {
     auto iter = data_channels.find(i);
     if (iter == data_channels.end()) {
       sid = i;
       break;
     }
   }
-  this->sctp->SetDataChannelSID(sid);  
+
+  this->sctp->SetDataChannelSID(sid);
+
+  auto new_channel = std::make_shared<DataChannel>(this, sid, DATA_CHANNEL_RELIABLE, label, protocol);
+  data_channels[sid] = new_channel;
+
   std::thread create_dc = std::thread(&SCTPWrapper::CreateDCForSCTP, sctp.get(), label, protocol);
   logger->info("Spawning create_dc thread");
   create_dc.detach();

src/SCTPWrapper.cpp

@@ -295,7 +295,7 @@ void SCTPWrapper::Stop() {
 
 void SCTPWrapper::DTLSForSCTP(ChunkPtr chunk) { this->recv_queue.push(chunk); }
 
-int SCTPWrapper::GetSid(){
+uint16_t SCTPWrapper::GetSid(){
     return this->sid;
   }
 
@@ -309,11 +309,23 @@ std::string SCTPWrapper::GetLabel(){
 std::string SCTPWrapper::GetProtocol(){
   return this->label;
   }
-void SCTPWrapper::SetDataChannelSID(int sid)
+void SCTPWrapper::SetDataChannelSID(uint16_t sid)
   {
     this->sid = sid;
   }
-
+void SCTPWrapper::SendACK() {
+    struct sctp_sndinfo sinfo = {0}; //
+    int sid;
+    sid = this->sid;
+    sinfo.snd_sid = sid;
+    sinfo.snd_ppid = htonl(PPID_CONTROL); 
+    uint8_t payload = DC_TYPE_ACK;
+    if (usrsctp_sendv(this->sock, &payload, sizeof(uint8_t), NULL, 0, &sinfo, sizeof(sinfo), SCTP_SENDV_SNDINFO, 0) < 0) {
+      logger->error("Sending ACK failed");
+    } else {
+      logger->info("Ack has gone through");
+    }
+}
 void SCTPWrapper::CreateDCForSCTP(std::string label, std::string protocol) {
 
   std::unique_lock<std::mutex> l2(createDCMtx);
@@ -322,7 +334,7 @@ void SCTPWrapper::CreateDCForSCTP(std::string label, std::string protocol) {
   }
   struct sctp_sndinfo sinfo = {0};
   int sid;
-  sid = this->sid ;
+  sid = this->sid;
   sinfo.snd_sid = sid;
   sinfo.snd_ppid = htonl(PPID_CONTROL);