Merge pull request #535 from paullouisageneau/fix-sctp-port

Handle different local and remote SCTP ports

src/impl/peerconnection.cpp

@@ -267,17 +267,23 @@ shared_ptr<SctpTransport> PeerConnection::initSctpTransport() {
 		if (!lower)
 			throw std::logic_error("No underlying DTLS transport for SCTP transport");
 
+		auto local = localDescription();
+		if (!local || !local->application())
+			throw std::logic_error("Starting SCTP transport without local application description");
+
 		auto remote = remoteDescription();
 		if (!remote || !remote->application())
-			throw std::logic_error("Starting SCTP transport without application description");
+			throw std::logic_error("Starting SCTP transport without remote application description");
 
-		uint16_t sctpPort = remote->application()->sctpPort().value_or(DEFAULT_SCTP_PORT);
+		SctpTransport::Ports ports = {};
+		ports.local = local->application()->sctpPort().value_or(DEFAULT_SCTP_PORT);
+		ports.remote = remote->application()->sctpPort().value_or(DEFAULT_SCTP_PORT);
 
 		// This is the last occasion to ensure the stream numbers are coherent with the role
 		shiftDataChannels();
 
 		auto transport = std::make_shared<SctpTransport>(
-		    lower, config, sctpPort, weak_bind(&PeerConnection::forwardMessage, this, _1),
+		    lower, config, std::move(ports), weak_bind(&PeerConnection::forwardMessage, this, _1),
 		    weak_bind(&PeerConnection::forwardBufferedAmount, this, _1, _2),
 		    [this, weak_this = weak_from_this()](SctpTransport::State transportState) {
 			    auto shared_this = weak_this.lock();

src/impl/sctptransport.cpp

@@ -178,11 +178,10 @@ void SctpTransport::Cleanup() {
 		std::this_thread::sleep_for(100ms);
 }
 
-SctpTransport::SctpTransport(shared_ptr<Transport> lower, const Configuration &config,
-                             uint16_t port, message_callback recvCallback,
-                             amount_callback bufferedAmountCallback,
+SctpTransport::SctpTransport(shared_ptr<Transport> lower, const Configuration &config, Ports ports,
+                             message_callback recvCallback, amount_callback bufferedAmountCallback,
                              state_callback stateChangeCallback)
-    : Transport(lower, std::move(stateChangeCallback)), mPort(port),
+    : Transport(lower, std::move(stateChangeCallback)), mPorts(std::move(ports)),
       mSendQueue(0, message_size_func), mBufferedAmountCallback(std::move(bufferedAmountCallback)) {
 	onRecv(std::move(recvCallback));
 
@@ -361,28 +360,34 @@ void SctpTransport::close() {
 	}
 }
 
-void SctpTransport::connect() {
-	if (!mSock)
-		throw std::logic_error("Attempted SCTP connect with closed socket");
-
-	PLOG_DEBUG << "SCTP connecting";
-	changeState(State::Connecting);
-
+struct sockaddr_conn SctpTransport::getSockAddrConn(uint16_t port) {
 	struct sockaddr_conn sconn = {};
 	sconn.sconn_family = AF_CONN;
-	sconn.sconn_port = htons(mPort);
+	sconn.sconn_port = htons(port);
 	sconn.sconn_addr = this;
 #ifdef HAVE_SCONN_LEN
 	sconn.sconn_len = sizeof(sconn);
 #endif
+	return sconn;
+}
+
+void SctpTransport::connect() {
+	if (!mSock)
+		throw std::logic_error("Attempted SCTP connect with closed socket");
+
+	PLOG_DEBUG << "SCTP connecting (local port=" << mPorts.local
+	           << ", remote port=" << mPorts.remote << ")";
+	changeState(State::Connecting);
 
-	if (usrsctp_bind(mSock, reinterpret_cast<struct sockaddr *>(&sconn), sizeof(sconn)))
+	auto local = getSockAddrConn(mPorts.local);
+	if (usrsctp_bind(mSock, reinterpret_cast<struct sockaddr *>(&local), sizeof(local)))
 		throw std::runtime_error("Could not bind usrsctp socket, errno=" + std::to_string(errno));
 
 	// According to RFC 8841, both endpoints must initiate the SCTP association, in a
 	// simultaneous-open manner, irrelevent to the SDP setup role.
 	// See https://tools.ietf.org/html/rfc8841#section-9.3
-	int ret = usrsctp_connect(mSock, reinterpret_cast<struct sockaddr *>(&sconn), sizeof(sconn));
+	auto remote = getSockAddrConn(mPorts.remote);
+	int ret = usrsctp_connect(mSock, reinterpret_cast<struct sockaddr *>(&remote), sizeof(remote));
 	if (ret && errno != EINPROGRESS)
 		throw std::runtime_error("Connection attempt failed, errno=" + std::to_string(errno));
 }

src/impl/sctptransport.hpp

@@ -42,7 +42,12 @@ public:
 
 	using amount_callback = std::function<void(uint16_t streamId, size_t amount)>;
 
-	SctpTransport(shared_ptr<Transport> lower, const Configuration &config, uint16_t port,
+	struct Ports {
+		uint16_t local = DEFAULT_SCTP_PORT;
+		uint16_t remote = DEFAULT_SCTP_PORT;
+	};
+
+	SctpTransport(shared_ptr<Transport> lower, const Configuration &config, Ports ports,
 	              message_callback recvCallback, amount_callback bufferedAmountCallback,
 	              state_callback stateChangeCallback);
 	~SctpTransport();
@@ -76,6 +81,8 @@ private:
 		PPID_BINARY_EMPTY = 57
 	};
 
+	struct sockaddr_conn getSockAddrConn(uint16_t port);
+
 	void connect();
 	void shutdown();
 	void close();
@@ -96,7 +103,7 @@ private:
 	void processData(binary &&data, uint16_t streamId, PayloadId ppid);
 	void processNotification(const union sctp_notification *notify, size_t len);
 
-	const uint16_t mPort;
+	const Ports mPorts;
 	struct socket *mSock;
 
 	Processor mProcessor;