Bumped version to 0.8.0

Add Data Channel reliability to C API

.github/workflows/build-gnutls.yml

@@ -16,7 +16,7 @@ jobs:
     - name: submodules
       run: git submodule update --init --recursive
     - name: cmake
-      run: cmake -B build -DUSE_GNUTLS=1
+      run: cmake -B build -DUSE_GNUTLS=1 -DWARNINGS_AS_ERRORS=1
     - name: make
       run: (cd build; make -j2)
     - name: test
@@ -30,7 +30,7 @@ jobs:
     - name: submodules
       run: git submodule update --init --recursive
     - name: cmake
-      run: cmake -B build -DUSE_GNUTLS=1
+      run: cmake -B build -DUSE_GNUTLS=1 -DWARNINGS_AS_ERRORS=1
     - name: make
       run: (cd build; make -j2)
     - name: test

.github/workflows/build-nice.yml

@@ -16,7 +16,7 @@ jobs:
     - name: submodules
       run: git submodule update --init --recursive
     - name: cmake
-      run: cmake -B build -DUSE_GNUTLS=1 -DUSE_NICE=1
+      run: cmake -B build -DUSE_GNUTLS=1 -DUSE_NICE=1 -DWARNINGS_AS_ERRORS=1
     - name: make
       run: (cd build; make -j2)
     - name: test

.github/workflows/build-openssl.yml

@@ -16,7 +16,7 @@ jobs:
     - name: submodules
       run: git submodule update --init --recursive
     - name: cmake
-      run: cmake -B build -DUSE_GNUTLS=0
+      run: cmake -B build -DUSE_GNUTLS=0 -DWARNINGS_AS_ERRORS=1
     - name: make
       run: (cd build; make -j2)
     - name: test
@@ -30,7 +30,7 @@ jobs:
     - name: submodules
       run: git submodule update --init --recursive
     - name: cmake
-      run: cmake -B build -DUSE_GNUTLS=0
+      run: cmake -B build -DUSE_GNUTLS=0 -WARNINGS_AS_ERRORS=1
       env:
         OPENSSL_ROOT_DIR: /usr/local/opt/openssl
         OPENSSL_LIBRARIES: /usr/local/opt/openssl/lib
@@ -48,7 +48,7 @@ jobs:
     - name: submodules
       run: git submodule update --init --recursive
     - name: cmake
-      run: cmake -B build -G "NMake Makefiles" -DUSE_GNUTLS=0
+      run: cmake -B build -G "NMake Makefiles" -DUSE_GNUTLS=0 -WARNINGS_AS_ERRORS=1
     - name: nmake
       run: |
         cd build

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.7)
 project(libdatachannel
 	DESCRIPTION "WebRTC Data Channels Library"
-	VERSION 0.7.1
+	VERSION 0.8.0
 	LANGUAGES CXX)
 
 # Options
@@ -10,6 +10,8 @@ option(USE_NICE "Use libnice instead of libjuice" OFF)
 option(USE_SRTP "Enable SRTP for media support" OFF)
 option(NO_WEBSOCKET "Disable WebSocket support" OFF)
 option(NO_EXAMPLES "Disable examples" OFF)
+option(NO_TESTS "Disable tests build" OFF)
+option(WARNINGS_AS_ERRORS "Treat warnings as errors" OFF)
 
 if(USE_NICE)
 	option(USE_JUICE "Use libjuice" OFF)
@@ -213,7 +215,23 @@ add_library(LibDataChannel::LibDataChannelStatic ALIAS datachannel-static)
 install(TARGETS datachannel LIBRARY DESTINATION lib)
 install(FILES ${LIBDATACHANNEL_HEADERS} DESTINATION include/rtc)
 
+if(NOT MSVC)
+	target_compile_options(datachannel PRIVATE -Wall -Wextra)
+	target_compile_options(datachannel-static PRIVATE -Wall -Wextra)
+endif()
+
+if(WARNINGS_AS_ERRORS)
+	if(MSVC)
+		target_compile_options(datachannel PRIVATE /WX)
+		target_compile_options(datachannel-static PRIVATE /WX)
+	else()
+		target_compile_options(datachannel PRIVATE -Werror)
+		target_compile_options(datachannel-static PRIVATE -Werror)
+	endif()
+endif()
+
 # Tests
+if(NOT NO_TESTS)
 	add_executable(datachannel-tests ${TESTS_SOURCES})
 	set_target_properties(datachannel-tests PROPERTIES
 		VERSION ${PROJECT_VERSION}
@@ -239,6 +257,7 @@ if(WIN32)
 	else()
 		target_link_libraries(datachannel-benchmark datachannel)
 	endif()
+endif()
 
 # Examples
 if(NOT NO_EXAMPLES)

README.md

@@ -1,6 +1,6 @@
 # libdatachannel - C/C++ WebRTC Data Channels
 
-libdatachannel is a standalone implementation of WebRTC Data Channels and WebSockets in C++17 with C bindings for POSIX platforms (including Linux and Apple macOS) and Microsoft Windows. It enables direct connectivity between native applications and web browsers without the pain of importing the entire WebRTC stack. The interface consists of simplified versions of the JavaScript WebRTC and WebSocket APIs present in browsers, in order to ease the design of cross-environment applications.
+libdatachannel is a standalone implementation of WebRTC Data Channels and WebSockets in C++17 with C bindings for POSIX platforms (including GNU/Linux, Android, and Apple macOS) and Microsoft Windows. It enables direct connectivity between native applications and web browsers without the pain of importing the entire WebRTC stack. The interface consists of simplified versions of the JavaScript WebRTC and WebSocket APIs present in browsers, in order to ease the design of cross-environment applications.
 It can be compiled with multiple backends:
 - The security layer can be provided through [OpenSSL](https://www.openssl.org/) or [GnuTLS](https://www.gnutls.org/).
 - The connectivity for WebRTC can be provided through my ad-hoc ICE library [libjuice](https://github.com/paullouisageneau/libjuice) as submodule or through [libnice](https://github.com/libnice/libnice).
@@ -197,6 +197,7 @@ ws->open("wss://my.websocket/service");
 ```
 
 ## External resources
-- Rust wrappers for libdatachannel: [datachannel-rs](https://github.com/lerouxrgd/datachannel-rs)
+- Rust wrapper for libdatachannel: [datachannel-rs](https://github.com/lerouxrgd/datachannel-rs)
-- WebAssembly wrappers compatible with libdatachannel: [datachannel-wasm](https://github.com/paullouisageneau/datachannel-wasm)
+- Node.js wrapper for libdatachannel: [node-datachannel](https://github.com/murat-dogan/node-datachannel)
+- WebAssembly wrapper compatible with libdatachannel: [datachannel-wasm](https://github.com/paullouisageneau/datachannel-wasm)
 

examples/web/server.js

@@ -98,5 +98,10 @@ wsServer.on('request', (req) => {
   clients[id] = conn;
 });
 
-httpServer.listen(8000);
+const hostname = '127.0.0.1';
+const port = 8000;
+
+httpServer.listen(port, hostname, () => {
+  console.log(`Server listening on ${hostname}:${port}`);
+});
 

include/rtc/reliability.hpp

@@ -27,13 +27,9 @@
 namespace rtc {
 
 struct Reliability {
-	enum Type : uint8_t {
+	enum class Type { Reliable = 0, Rexmit, Timed };
-		TYPE_RELIABLE = 0x00,
-		TYPE_PARTIAL_RELIABLE_REXMIT = 0x01,
-		TYPE_PARTIAL_RELIABLE_TIMED = 0x02,
-	};
 
-	Type type = TYPE_RELIABLE;
+	Type type = Type::Reliable;
 	bool unordered = false;
 	std::variant<int, std::chrono::milliseconds> rexmit = 0;
 };

include/rtc/rtc.h

@@ -78,6 +78,13 @@ typedef struct {
 	uint16_t portRangeEnd;
 } rtcConfiguration;
 
+typedef struct {
+	bool unordered;
+	bool unreliable;
+	unsigned int maxPacketLifeTime; // ignored if reliable
+	unsigned int maxRetransmits;    // ignored if reliable
+} rtcReliability;
+
 typedef void (*rtcLogCallbackFunc)(rtcLogLevel level, const char *message);
 typedef void (*rtcDataChannelCallbackFunc)(int dc, void *ptr);
 typedef void (*rtcDescriptionCallbackFunc)(const char *sdp, const char *type, void *ptr);
@@ -115,9 +122,13 @@ RTC_EXPORT int rtcGetRemoteAddress(int pc, char *buffer, int size);
 
 // DataChannel
 RTC_EXPORT int rtcCreateDataChannel(int pc, const char *label); // returns dc id
+RTC_EXPORT int rtcCreateDataChannelExt(int pc, const char *label, const char *protocol,
+                                       const rtcReliability *reliability); // returns dc id
 RTC_EXPORT int rtcDeleteDataChannel(int dc);
 
 RTC_EXPORT int rtcGetDataChannelLabel(int dc, char *buffer, int size);
+RTC_EXPORT int rtcGetDataChannelProtocol(int dc, char *buffer, int size);
+RTC_EXPORT int rtcGetDataChannelReliability(int dc, rtcReliability *reliability);
 
 // WebSocket
 #if RTC_ENABLE_WEBSOCKET

src/datachannel.cpp

@@ -31,6 +31,7 @@ namespace rtc {
 
 using std::shared_ptr;
 using std::weak_ptr;
+using std::chrono::milliseconds;
 
 // Messages for the DataChannel establishment protocol
 // See https://tools.ietf.org/html/draft-ietf-rtcweb-data-protocol-09
@@ -43,6 +44,12 @@ enum MessageType : uint8_t {
 	MESSAGE_CLOSE = 0x04
 };
 
+enum ChannelType : uint8_t {
+	CHANNEL_RELIABLE = 0x00,
+	CHANNEL_PARTIAL_RELIABLE_REXMIT = 0x01,
+	CHANNEL_PARTIAL_RELIABLE_TIMED = 0x02
+};
+
 #pragma pack(push, 1)
 struct OpenMessage {
 	uint8_t type = MESSAGE_OPEN;
@@ -168,22 +175,33 @@ size_t DataChannel::availableAmount() const { return mRecvQueue.amount(); }
 void DataChannel::open(shared_ptr<SctpTransport> transport) {
 	mSctpTransport = transport;
 
-	uint8_t channelType = static_cast<uint8_t>(mReliability->type);
+	uint8_t channelType;
-	if (mReliability->unordered)
+	uint32_t reliabilityParameter;
-		channelType &= 0x80;
+	switch (mReliability->type) {
-
+	case Reliability::Type::Rexmit:
-	using std::chrono::milliseconds;
+		channelType = CHANNEL_PARTIAL_RELIABLE_REXMIT;
-	uint32_t reliabilityParameter = 0;
-	if (mReliability->type == Reliability::TYPE_PARTIAL_RELIABLE_REXMIT)
 		reliabilityParameter = uint32_t(std::get<int>(mReliability->rexmit));
-	else if (mReliability->type == Reliability::TYPE_PARTIAL_RELIABLE_TIMED)
+		break;
+
+	case Reliability::Type::Timed:
+		channelType = CHANNEL_PARTIAL_RELIABLE_TIMED;
 		reliabilityParameter = uint32_t(std::get<milliseconds>(mReliability->rexmit).count());
+		break;
+
+	default:
+		channelType = CHANNEL_RELIABLE;
+		reliabilityParameter = 0;
+		break;
+	}
+
+	if (mReliability->unordered)
+		channelType |= 0x80;
 
 	const size_t len = sizeof(OpenMessage) + mLabel.size() + mProtocol.size();
 	binary buffer(len, byte(0));
 	auto &open = *reinterpret_cast<OpenMessage *>(buffer.data());
 	open.type = MESSAGE_OPEN;
-	open.channelType = mReliability->type;
+	open.channelType = channelType;
 	open.priority = htons(0);
 	open.reliabilityParameter = htonl(reliabilityParameter);
 	open.labelLength = htons(uint16_t(mLabel.size()));
@@ -272,19 +290,18 @@ void DataChannel::processOpenMessage(message_ptr message) {
 	mLabel.assign(end, open.labelLength);
 	mProtocol.assign(end + open.labelLength, open.protocolLength);
 
-	using std::chrono::milliseconds;
 	mReliability->unordered = (open.reliabilityParameter & 0x80) != 0;
 	switch (open.channelType & 0x7F) {
-	case Reliability::TYPE_PARTIAL_RELIABLE_REXMIT:
+	case CHANNEL_PARTIAL_RELIABLE_REXMIT:
-		mReliability->type = Reliability::TYPE_PARTIAL_RELIABLE_REXMIT;
+		mReliability->type = Reliability::Type::Rexmit;
 		mReliability->rexmit = int(open.reliabilityParameter);
 		break;
-	case Reliability::TYPE_PARTIAL_RELIABLE_TIMED:
+	case CHANNEL_PARTIAL_RELIABLE_TIMED:
-		mReliability->type = Reliability::TYPE_PARTIAL_RELIABLE_TIMED;
+		mReliability->type = Reliability::Type::Timed;
 		mReliability->rexmit = milliseconds(open.reliabilityParameter);
 		break;
 	default:
-		mReliability->type = Reliability::TYPE_RELIABLE;
+		mReliability->type = Reliability::Type::Reliable;
 		mReliability->rexmit = int(0);
 	}
 

src/icetransport.cpp

@@ -622,7 +622,8 @@ void IceTransport::CandidateCallback(NiceAgent *agent, NiceCandidate *candidate,
 	g_free(cand);
 }
 
-void IceTransport::GatheringDoneCallback(NiceAgent *agent, guint streamId, gpointer userData) {
+void IceTransport::GatheringDoneCallback(NiceAgent * /*agent*/, guint /*streamId*/,
+                                         gpointer userData) {
 	auto iceTransport = static_cast<rtc::IceTransport *>(userData);
 	try {
 		iceTransport->processGatheringDone();
@@ -631,8 +632,8 @@ void IceTransport::GatheringDoneCallback(NiceAgent *agent, guint streamId, gpoin
 	}
 }
 
-void IceTransport::StateChangeCallback(NiceAgent *agent, guint streamId, guint componentId,
+void IceTransport::StateChangeCallback(NiceAgent * /*agent*/, guint /*streamId*/,
-                                       guint state, gpointer userData) {
+                                       guint /*componentId*/, guint state, gpointer userData) {
 	auto iceTransport = static_cast<rtc::IceTransport *>(userData);
 	try {
 		iceTransport->processStateChange(state);
@@ -641,8 +642,8 @@ void IceTransport::StateChangeCallback(NiceAgent *agent, guint streamId, guint c
 	}
 }
 
-void IceTransport::RecvCallback(NiceAgent *agent, guint streamId, guint componentId, guint len,
+void IceTransport::RecvCallback(NiceAgent * /*agent*/, guint /*streamId*/, guint /*componentId*/,
-                                gchar *buf, gpointer userData) {
+                                guint len, gchar *buf, gpointer userData) {
 	auto iceTransport = static_cast<rtc::IceTransport *>(userData);
 	try {
 		PLOG_VERBOSE << "Incoming size=" << len;
@@ -663,8 +664,8 @@ gboolean IceTransport::TimeoutCallback(gpointer userData) {
 	return FALSE;
 }
 
-void IceTransport::LogCallback(const gchar *logDomain, GLogLevelFlags logLevel,
+void IceTransport::LogCallback(const gchar * /*logDomain*/, GLogLevelFlags logLevel,
-                               const gchar *message, gpointer userData) {
+                               const gchar *message, gpointer /*userData*/) {
 	plog::Severity severity;
 	unsigned int flags = logLevel & G_LOG_LEVEL_MASK;
 	if (flags & G_LOG_LEVEL_ERROR)
@@ -708,7 +709,7 @@ bool IceTransport::getSelectedCandidatePair(CandidateInfo *localInfo, CandidateI
 	return true;
 }
 
-const CandidateType IceTransport::NiceTypeToCandidateType(NiceCandidateType type) {
+CandidateType IceTransport::NiceTypeToCandidateType(NiceCandidateType type) {
 	switch (type) {
 	case NiceCandidateType::NICE_CANDIDATE_TYPE_PEER_REFLEXIVE:
 		return CandidateType::PeerReflexive;
@@ -721,7 +722,7 @@ const CandidateType IceTransport::NiceTypeToCandidateType(NiceCandidateType type
 	}
 }
 
-const CandidateTransportType
+CandidateTransportType
 IceTransport::NiceTransportTypeToCandidateTransportType(NiceCandidateTransport type) {
 	switch (type) {
 	case NiceCandidateTransport::NICE_CANDIDATE_TRANSPORT_TCP_ACTIVE:

src/icetransport.hpp

@@ -113,8 +113,9 @@ private:
 	static gboolean TimeoutCallback(gpointer userData);
 	static void LogCallback(const gchar *log_domain, GLogLevelFlags log_level, const gchar *message,
 	                        gpointer user_data);
-	static const CandidateType NiceTypeToCandidateType(NiceCandidateType type);
+	static CandidateType NiceTypeToCandidateType(NiceCandidateType type);
-	static const CandidateTransportType NiceTransportTypeToCandidateTransportType(NiceCandidateTransport type);
+	static CandidateTransportType
+	NiceTransportTypeToCandidateTransportType(NiceCandidateTransport type);
 #endif
 };
 

src/peerconnection.cpp

@@ -82,6 +82,8 @@ std::optional<Description> PeerConnection::remoteDescription() const {
 }
 
 void PeerConnection::setLocalDescription(std::optional<Description> description) {
+	PLOG_VERBOSE << "Setting local description";
+
 	if (auto iceTransport = std::atomic_load(&mIceTransport)) {
 		throw std::logic_error("Local description is already set");
 	} else {
@@ -98,6 +100,8 @@ void PeerConnection::setLocalDescription(std::optional<Description> description)
 }
 
 void PeerConnection::setRemoteDescription(Description description) {
+	PLOG_VERBOSE << "Setting remote description: " << string(description);
+
 	description.hintType(localDescription() ? Description::Type::Answer : Description::Type::Offer);
 	auto type = description.type();
 	auto remoteCandidates = description.extractCandidates(); // Candidates will be added at the end
@@ -143,6 +147,7 @@ void PeerConnection::setRemoteDescription(Description description) {
 }
 
 void PeerConnection::addRemoteCandidate(Candidate candidate) {
+	PLOG_VERBOSE << "Adding remote candidate: " << string(candidate);
 
 	auto iceTransport = std::atomic_load(&mIceTransport);
 	if (!mRemoteDescription || !iceTransport)
@@ -243,7 +248,7 @@ void PeerConnection::onMedia(std::function<void(const binary &packet)> callback)
 	mMediaCallback = callback;
 }
 
-void PeerConnection::outgoingMedia(message_ptr message) {
+void PeerConnection::outgoingMedia([[maybe_unused]] message_ptr message) {
 	if (!hasMedia())
 		throw std::runtime_error("PeerConnection has no media support");
 
@@ -657,7 +662,7 @@ bool PeerConnection::changeState(State state) {
 
 	if (state == State::Closed)
 		// This is the last state change, so we may steal the callback
-		mProcessor->enqueue([this, cb = std::move(mStateChangeCallback)]() { cb(State::Closed); });
+		mProcessor->enqueue([cb = std::move(mStateChangeCallback)]() { cb(State::Closed); });
 	else
 		mProcessor->enqueue([this, state]() { mStateChangeCallback(state); });
 

src/rtc.cpp

@@ -29,6 +29,7 @@
 
 #include "plog/Formatters/FuncMessageFormatter.h"
 
+#include <chrono>
 #include <exception>
 #include <mutex>
 #include <type_traits>
@@ -43,6 +44,7 @@
 using namespace rtc;
 using std::shared_ptr;
 using std::string;
+using std::chrono::milliseconds;
 
 namespace {
 
@@ -241,9 +243,30 @@ int rtcDeletePeerConnection(int pc) {
 }
 
 int rtcCreateDataChannel(int pc, const char *label) {
+	return rtcCreateDataChannelExt(pc, label, nullptr, nullptr);
+}
+
+int rtcCreateDataChannelExt(int pc, const char *label, const char *protocol,
+                            const rtcReliability *reliability) {
 	return WRAP({
+		Reliability r = {};
+		if (reliability) {
+			r.unordered = reliability->unordered;
+			if (reliability->unreliable) {
+				if (reliability->maxPacketLifeTime > 0) {
+					r.type = Reliability::Type::Timed;
+					r.rexmit = milliseconds(reliability->maxPacketLifeTime);
+				} else {
+					r.type = Reliability::Type::Rexmit;
+					r.rexmit = int(reliability->maxRetransmits);
+				}
+			} else {
+				r.type = Reliability::Type::Reliable;
+			}
+		}
 		auto peerConnection = getPeerConnection(pc);
-		int dc = emplaceDataChannel(peerConnection->createDataChannel(string(label)));
+		int dc = emplaceDataChannel(peerConnection->createDataChannel(
+		    string(label ? label : ""), string(protocol ? protocol : ""), r));
 		if (auto ptr = getUserPointer(pc))
 			rtcSetUserPointer(dc, *ptr);
 		return dc;
@@ -447,6 +470,48 @@ int rtcGetDataChannelLabel(int dc, char *buffer, int size) {
 	});
 }
 
+int rtcGetDataChannelProtocol(int dc, char *buffer, int size) {
+	return WRAP({
+		auto dataChannel = getDataChannel(dc);
+
+		if (!buffer)
+			throw std::invalid_argument("Unexpected null pointer");
+
+		if (size <= 0)
+			return 0;
+
+		string protocol = dataChannel->protocol();
+		const char *data = protocol.data();
+		size = std::min(size - 1, int(protocol.size()));
+		std::copy(data, data + size, buffer);
+		buffer[size] = '\0';
+		return int(size + 1);
+	});
+}
+
+int rtcGetDataChannelReliability(int dc, rtcReliability *reliability) {
+	return WRAP({
+		auto dataChannel = getDataChannel(dc);
+
+		if (!reliability)
+			throw std::invalid_argument("Unexpected null pointer");
+
+		Reliability r = dataChannel->reliability();
+		std::memset(reliability, 0, sizeof(*reliability));
+		reliability->unordered = r.unordered;
+		if (r.type == Reliability::Type::Timed) {
+			reliability->unreliable = true;
+			reliability->maxPacketLifeTime = unsigned(std::get<milliseconds>(r.rexmit).count());
+		} else if (r.type == Reliability::Type::Rexmit) {
+			reliability->unreliable = true;
+			reliability->maxRetransmits = unsigned(std::get<int>(r.rexmit));
+		} else {
+			reliability->unreliable = false;
+		}
+		return 0;
+	});
+}
+
 int rtcSetOpenCallback(int id, rtcOpenCallbackFunc cb) {
 	return WRAP({
 		auto channel = getChannel(id);

src/sctptransport.cpp

@@ -372,12 +372,12 @@ bool SctpTransport::trySendMessage(message_ptr message) {
 		spa.sendv_sndinfo.snd_flags |= SCTP_UNORDERED;
 
 	switch (reliability.type) {
-	case Reliability::TYPE_PARTIAL_RELIABLE_REXMIT:
+	case Reliability::Type::Rexmit:
 		spa.sendv_flags |= SCTP_SEND_PRINFO_VALID;
 		spa.sendv_prinfo.pr_policy = SCTP_PR_SCTP_RTX;
 		spa.sendv_prinfo.pr_value = uint32_t(std::get<int>(reliability.rexmit));
 		break;
-	case Reliability::TYPE_PARTIAL_RELIABLE_TIMED:
+	case Reliability::Type::Timed:
 		spa.sendv_flags |= SCTP_SEND_PRINFO_VALID;
 		spa.sendv_prinfo.pr_policy = SCTP_PR_SCTP_TTL;
 		spa.sendv_prinfo.pr_value = uint32_t(std::get<milliseconds>(reliability.rexmit).count());
@@ -676,8 +676,16 @@ std::optional<milliseconds> SctpTransport::rtt() {
 
 int SctpTransport::RecvCallback(struct socket *sock, union sctp_sockstore addr, void *data,
                                 size_t len, struct sctp_rcvinfo recv_info, int flags, void *ptr) {
-	int ret = static_cast<SctpTransport *>(ptr)->handleRecv(
+	auto *transport = static_cast<SctpTransport *>(ptr);
-	    sock, addr, static_cast<const byte *>(data), len, recv_info, flags);
+
+	std::shared_lock lock(InstancesMutex);
+	if (Instances.find(transport) == Instances.end()) {
+		free(data);
+		return -1;
+	}
+
+	int ret =
+	    transport->handleRecv(sock, addr, static_cast<const byte *>(data), len, recv_info, flags);
 	free(data);
 	return ret;
 }
@@ -692,8 +700,6 @@ int SctpTransport::SendCallback(struct socket *sock, uint32_t sb_free) {
 	void *ptr = sconn->sconn_addr;
 	auto *transport = static_cast<SctpTransport *>(ptr);
 
-	// Workaround for sctplab/usrsctp#405: Send callback is invoked on already closed socket
-	// https://github.com/sctplab/usrsctp/issues/405
 	std::shared_lock lock(InstancesMutex);
 	if (Instances.find(transport) == Instances.end())
 		return -1;
@@ -702,8 +708,15 @@ int SctpTransport::SendCallback(struct socket *sock, uint32_t sb_free) {
 }
 
 int SctpTransport::WriteCallback(void *ptr, void *data, size_t len, uint8_t tos, uint8_t set_df) {
-	return static_cast<SctpTransport *>(ptr)->handleWrite(static_cast<byte *>(data), len, tos,
+	auto *transport = static_cast<SctpTransport *>(ptr);
-	                                                      set_df);
+
+	// Workaround for sctplab/usrsctp#405: Send callback is invoked on already closed socket
+	// https://github.com/sctplab/usrsctp/issues/405
+	std::shared_lock lock(InstancesMutex);
+	if (Instances.find(transport) == Instances.end())
+		return -1;
+
+	return transport->handleWrite(static_cast<byte *>(data), len, tos, set_df);
 }
 
 } // namespace rtc

src/tcptransport.cpp

@@ -54,7 +54,7 @@ SelectInterrupter::~SelectInterrupter() {
 #endif
 }
 
-int SelectInterrupter::prepare(fd_set &readfds, fd_set &writefds) {
+int SelectInterrupter::prepare(fd_set &readfds, [[maybe_unused]] fd_set &writefds) {
 	std::lock_guard lock(mMutex);
 #ifdef _WIN32
 	if (mDummySock == INVALID_SOCKET)