Fix "SCTP failed" if no DataChannel is created on a Transport with enableSctp: true

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Convert `WORKER_CLOSE` into a notification ([PR #1729](https://github.com/versatica/mediasoup/pull/1729).
 - Node tests: Replace `sctp` unmaintained library with `werift-sctp` ([PR #1732](https://github.com/versatica/mediasoup/pull/1732), thanks to @shinyoshiaki for his help with `werift-sctp`.
 - Worker: Require C++20 ([PR #1741](https://github.com/versatica/mediasoup/pull/1741).
+- Fix "SCTP failed" if no DataChannel is created on a Transport with `enableSctp: true` ([PR #1749](https://github.com/versatica/mediasoup/pull/1749).
 
 ### 3.19.17
 

node/src/test/test-werift-sctp.ts

@@ -35,31 +35,19 @@ beforeEach(async () => {
 		numSctpStreams: { OS: 256, MIS: 256 },
 	});
 
+	// Create an explicit SCTP outgoing stream id.
+	ctx.sctpSendStreamId = 123;
+
 	ctx.sctpClient = SCTP.client(
 		createSctpUdpTransport(createSocket('udp4'), {
 			port: ctx.plainTransport.tuple.localPort,
 			address: ctx.plainTransport.tuple.localAddress,
 		})
 	);
 
-	await ctx.sctpClient.start(5000);
-
-	let connectionTimeoutTimer: NodeJS.Timeout | undefined;
-
-	await Promise.race([
-		ctx.sctpClient.stateChanged.connected.asPromise(),
-		new Promise<void>((resolve, reject) => {
-			connectionTimeoutTimer = setTimeout(
-				() => reject(new Error('SCTP connection timeout')),
-				3000
-			);
-		}),
-	]);
-
-	clearTimeout(connectionTimeoutTimer);
-
-	// Create an explicit SCTP outgoing stream id.
-	ctx.sctpSendStreamId = 123;
+	// NOTE: We don't await it on purpose since we don't want to block here until
+	// SCTP connects.
+	void ctx.sctpClient.start(5000);
 
 	// Create a DataProducer with the corresponding SCTP stream id.
 	ctx.dataProducer = await ctx.plainTransport.produceData({
@@ -76,6 +64,41 @@ beforeEach(async () => {
 	ctx.dataConsumer = await ctx.plainTransport.consumeData({
 		dataProducerId: ctx.dataProducer.id,
 	});
+
+	let connectionTimeoutTimer: NodeJS.Timeout | undefined;
+
+	await Promise.race([
+		// Wait for SCTP to become connected in both the PlainTransport and in the
+		// werift-sctp client.
+		Promise.all([
+			ctx.sctpClient.stateChanged.connected.asPromise(),
+			new Promise<void>((resolve, reject) => {
+				if (ctx.plainTransport?.sctpState === 'connected') {
+					resolve();
+				} else {
+					ctx.plainTransport?.on('sctpstatechange', state => {
+						if (state === 'connected') {
+							resolve();
+						} else if (state === 'failed' || state === 'closed') {
+							reject(
+								new Error(
+									'SCTP connection in PlainTransport failed or was closed'
+								)
+							);
+						}
+					});
+				}
+			}),
+		]),
+		new Promise<void>((resolve, reject) => {
+			connectionTimeoutTimer = setTimeout(
+				() => reject(new Error('SCTP connection timeout')),
+				3000
+			);
+		}),
+	]);
+
+	clearTimeout(connectionTimeoutTimer);
 });
 
 afterEach(async () => {

worker/include/RTC/SctpAssociation.hpp

@@ -81,6 +81,7 @@ namespace RTC
 		flatbuffers::Offset<FBS::SctpParameters::SctpParameters> FillBuffer(
 		  flatbuffers::FlatBufferBuilder& builder) const;
 		void TransportConnected();
+		void TransportDisconnected();
 		SctpState GetState() const
 		{
 			return this->state;
@@ -89,18 +90,20 @@ namespace RTC
 		{
 			return this->sctpBufferedAmount;
 		}
-		void ProcessSctpData(const uint8_t* data, size_t len) const;
+		void ProcessSctpData(const uint8_t* data, size_t len);
 		void SendSctpMessage(
 		  RTC::DataConsumer* dataConsumer,
 		  const uint8_t* msg,
 		  size_t len,
 		  uint32_t ppid,
 		  onQueuedCallback* cb = nullptr);
+		void HandleDataProducer(RTC::DataProducer* dataProducer);
 		void HandleDataConsumer(RTC::DataConsumer* dataConsumer);
 		void DataProducerClosed(RTC::DataProducer* dataProducer);
 		void DataConsumerClosed(RTC::DataConsumer* dataConsumer);
 
 	private:
+		void MayConnect();
 		void ResetSctpStream(uint16_t streamId, StreamDirection direction) const;
 		void AddOutgoingStreams(bool force = false);
 
@@ -131,6 +134,12 @@ namespace RTC
 		struct socket* socket{ nullptr };
 		uint16_t desiredOs{ 0u };
 		size_t messageBufferLen{ 0u };
+		bool transportConnected{ false };
+		// Whether at least one SCTP stream (AKA DataProducer or DataConsumer) has
+		// already been created, no matter it's still alive.
+		bool firstStreamCreated{ false };
+		// Whether we have received STCP data from the remote peer.
+		bool sctpDataReceived{ false };
 		uint16_t lastSsnReceived{ 0u }; // Valid for us since no SCTP I-DATA support.
 	};
 } // namespace RTC

worker/src/RTC/PipeTransport.cpp

@@ -486,7 +486,7 @@ namespace RTC
 
 	inline bool PipeTransport::IsConnected() const
 	{
-		return this->tuple;
+		return this->tuple ? true : false;
 	}
 
 	inline bool PipeTransport::HasSrtp() const

worker/src/RTC/PlainTransport.cpp

@@ -6,6 +6,10 @@
 #include "MediaSoupErrors.hpp"
 #include "Settings.hpp"
 #include "Utils.hpp"
+// TODO: For testing purposes. Must be removed.
+#ifdef MS_SCTP_STACK
+#include "RTC/SCTP/packet/Packet.hpp"
+#endif
 
 namespace RTC
 {
@@ -788,7 +792,7 @@ namespace RTC
 
 	inline bool PlainTransport::IsConnected() const
 	{
-		return this->tuple;
+		return this->tuple ? true : false;
 	}
 
 	inline bool PlainTransport::HasSrtp() const
@@ -913,9 +917,29 @@ namespace RTC
 
 		if (!IsConnected())
 		{
+			MS_WARN_TAG(sctp, "not connected, cannot send SCTP data");
+
 			return;
 		}
 
+// TODO: For testing purposes. Must be removed.
+#ifdef MS_SCTP_STACK
+		MS_DUMP(">>> sending SCTP packet...");
+
+		const auto* packet = RTC::SCTP::Packet::Parse(data, len);
+
+		if (packet)
+		{
+			packet->Dump();
+
+			delete packet;
+		}
+		else
+		{
+			MS_ABORT("RTC::SCTP::Packet::Parse() failed to parse sent SCTP data");
+		}
+#endif
+
 		this->tuple->Send(data, len);
 
 		// Increase send transmission.
@@ -1209,6 +1233,24 @@ namespace RTC
 			return;
 		}
 
+// TODO: For testing purposes. Must be removed.
+#ifdef MS_SCTP_STACK
+		MS_DUMP("<<< received SCTP packet...");
+
+		const auto* packet = RTC::SCTP::Packet::Parse(data, len);
+
+		if (packet)
+		{
+			packet->Dump();
+
+			delete packet;
+		}
+		else
+		{
+			MS_ABORT("RTC::SCTP::Packet::Parse() failed to parse received SCTP data");
+		}
+#endif
+
 		// Pass it to the parent transport.
 		RTC::Transport::ReceiveSctpData(data, len);
 	}