Updated Readme with gathering state callback

README.md

@@ -8,7 +8,7 @@ Licensed under LGPLv2, see [LICENSE](https://github.com/paullouisageneau/libdata
 
 ## Compatibility
 
-This implementation has been tested to be compatible with Firefox and Chromium. It supports Multicast DNS candidates resolution provided the operating system also supports it.
+This implementation has been tested to be compatible with Firefox and Chromium. It supports IPv6 and Multicast DNS candidates resolution provided the operating system also supports it.
 
 ## Dependencies
 
@@ -21,13 +21,13 @@ Submodules:
 ## Building
 
 ```bash
-git submodule update --init --recursive
-make
+$ git submodule update --init --recursive
+$ make
 ```
 
 ## Example
 
-In the following example, notes the callbacks are called in another thread.
+In the following example, note the callbacks are called in another thread.
 
 ### Signal a PeerConnection
 
@@ -37,7 +37,7 @@ In the following example, notes the callbacks are called in another thread.
 
 ```cpp
 rtc::Configuration config;
-config.iceServers.emplace_back("stunserver.org:3478");
+config.iceServers.emplace_back("mystunserver.org:3478");
 
 auto pc = make_shared<rtc::PeerConnection>(config);
 
@@ -46,12 +46,8 @@ pc->onLocalDescription([](const rtc::Description &sdp) {
     MY_SEND_DESCRIPTION_TO_REMOTE(string(sdp));
 });
 
-pc->onLocalCandidate([](const optional<rtc::Candidate> &candidate) {
-    if (candidate) {
-        MY_SEND_CANDIDATE_TO_REMOTE(candidate->candidate(), candidate->mid());
-    } else {
-        // Gathering finished
-    }
+pc->onLocalCandidate([](const rtc::Candidate &candidate) {
+    MY_SEND_CANDIDATE_TO_REMOTE(candidate.candidate(), candidate.mid());
 });
 
 MY_ON_RECV_DESCRIPTION_FROM_REMOTE([pc](string sdp) {
@@ -63,6 +59,19 @@ MY_ON_RECV_CANDIDATE_FROM_REMOTE([pc](string candidate, string mid) {
 });
 ```
 
+### Observe the PeerConnection state
+
+```cpp
+pc->onStateChanged([](PeerConnection::State state) {
+    cout << "State: " << state << endl;
+});
+
+pc->onGatheringStateChanged([](PeerConnection::GatheringState state) {
+    cout << "Gathering state: " << state << endl;
+});
+
+```
+
 ### Create a DataChannel
 
 ```cpp
@@ -81,7 +90,7 @@ dc->onMessage([](const variant<binary, string> &message) {
 
 ```cpp
 shared_ptr<rtc::DataChannel> dc;
-pc->onDataChannel([&dc](const shared_ptr<rtc::DataChannel> &incoming) {
+pc->onDataChannel([&dc](shared_ptr<rtc::DataChannel> incoming) {
     dc = incoming;
     dc->send("Hello world!");
 });

include/rtc/description.hpp

@@ -47,7 +47,8 @@ public:
 
 	void setFingerprint(string fingerprint);
 	void setSctpPort(uint16_t port);
-	void addCandidate(std::optional<Candidate> candidate);
+	void addCandidate(Candidate candidate);
+	void endCandidates();
 
 	operator string() const;
 

include/rtc/peerconnection.hpp

@@ -20,12 +20,13 @@
 #define RTC_PEER_CONNECTION_H
 
 #include "candidate.hpp"
+#include "configuration.hpp"
 #include "datachannel.hpp"
 #include "description.hpp"
-#include "configuration.hpp"
 #include "include.hpp"
 #include "message.hpp"
 #include "reliability.hpp"
+#include "rtc.hpp"
 
 #include <atomic>
 #include <functional>
@@ -40,12 +41,28 @@ class SctpTransport;
 
 class PeerConnection {
 public:
+	enum class State : int {
+		New = RTC_NEW,
+		Connecting = RTC_CONNECTING,
+		Connected = RTC_CONNECTED,
+		Disconnected = RTC_DISCONNECTED,
+		Failed = RTC_FAILED,
+		Closed = RTC_CLOSED
+	};
+
+	enum class GatheringState : int {
+		New = RTC_GATHERING_NEW,
+		InProgress = RTC_GATHERING_INPROGRESS,
+		Complete = RTC_GATHERING_COMPLETE,
+	};
+
 	PeerConnection(void);
 	PeerConnection(const Configuration &config);
 	~PeerConnection();
 
 	const Configuration *config() const;
-
+	State state() const;
+	GatheringState gatheringState() const;
 	std::optional<Description> localDescription() const;
 	std::optional<Description> remoteDescription() const;
 
@@ -57,7 +74,9 @@ public:
 
 	void onDataChannel(std::function<void(std::shared_ptr<DataChannel> dataChannel)> callback);
 	void onLocalDescription(std::function<void(const Description &description)> callback);
-	void onLocalCandidate(std::function<void(const std::optional<Candidate> &candidate)> callback);
+	void onLocalCandidate(std::function<void(const Candidate &candidate)> callback);
+	void onStateChange(std::function<void(State state)> callback);
+	void onGatheringStateChange(std::function<void(GatheringState state)> callback);
 
 private:
 	void initIceTransport(Description::Role role);
@@ -66,11 +85,15 @@ private:
 
 	bool checkFingerprint(const std::string &fingerprint) const;
 	void forwardMessage(message_ptr message);
-	void openDataChannels(void);
+	void iterateDataChannels(std::function<void(std::shared_ptr<DataChannel> channel)> func);
+	void openDataChannels();
+	void closeDataChannels();
 
 	void processLocalDescription(Description description);
-	void processLocalCandidate(std::optional<Candidate> candidate);
+	void processLocalCandidate(Candidate candidate);
 	void triggerDataChannel(std::shared_ptr<DataChannel> dataChannel);
+	void changeState(State state);
+	void changeGatheringState(GatheringState state);
 
 	const Configuration mConfig;
 	const std::shared_ptr<Certificate> mCertificate;
@@ -84,11 +107,19 @@ private:
 
 	std::unordered_map<unsigned int, std::weak_ptr<DataChannel>> mDataChannels;
 
+	std::atomic<State> mState;
+	std::atomic<GatheringState> mGatheringState;
+
 	std::function<void(std::shared_ptr<DataChannel> dataChannel)> mDataChannelCallback;
 	std::function<void(const Description &description)> mLocalDescriptionCallback;
-	std::function<void(const std::optional<Candidate> &candidate)> mLocalCandidateCallback;
+	std::function<void(const Candidate &candidate)> mLocalCandidateCallback;
+	std::function<void(State state)> mStateChangeCallback;
+	std::function<void(GatheringState state)> mGatheringStateChangeCallback;
 };
 
 } // namespace rtc
 
+std::ostream &operator<<(std::ostream &out, const rtc::PeerConnection::State &state);
+std::ostream &operator<<(std::ostream &out, const rtc::PeerConnection::GatheringState &state);
+
 #endif

include/rtc/rtc.h

@@ -16,11 +16,30 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#ifndef RTC_C_API
+#define RTC_C_API
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 // libdatachannel rtc C API
+
+typedef enum {
+	RTC_NEW = 0,
+	RTC_CONNECTING = 1,
+	RTC_CONNECTED = 2,
+	RTC_DISCONNECTED = 3,
+	RTC_FAILED = 4,
+	RTC_CLOSED = 5
+} rtc_state_t;
+
+typedef enum {
+	RTC_GATHERING_NEW = 0,
+	RTC_GATHERING_INPROGRESS = 1,
+	RTC_GATHERING_COMPLETE = 2
+} rtc_gathering_state_t;
+
 int rtcCreatePeerConnection(const char **iceServers, int iceServersCount);
 void rtcDeletePeerConnection(int pc);
 int rtcCreateDataChannel(int pc, const char *label);
@@ -30,6 +49,10 @@ void rtcSetLocalDescriptionCallback(int pc, void (*descriptionCallback)(const ch
                                                                         void *));
 void rtcSetLocalCandidateCallback(int pc,
                                   void (*candidateCallback)(const char *, const char *, void *));
+void rtcSetStateChangeCallback(int pc, void (*stateCallback)(rtc_state_t state, void *));
+void rtcSetGatheringStateChangeCallback(int pc,
+                                         void (*gatheringStateCallback)(rtc_gathering_state_t state,
+                                                                        void *));
 void rtcSetRemoteDescription(int pc, const char *sdp, const char *type);
 void rtcAddRemoteCandidate(int pc, const char *candidate, const char *mid);
 int rtcGetDataChannelLabel(int dc, char *data, int size);
@@ -43,3 +66,5 @@ void rtcSetUserPointer(int i, void *ptr);
 } // extern "C"
 #endif
 
+#endif
+

src/candidate.cpp

@@ -81,7 +81,7 @@ Candidate::Candidate(string candidate, string mid) {
 						ss << foundation << sp << component << sp << transport << sp << priority;
 						ss << sp << nodebuffer << sp << servbuffer << sp << "typ" << sp << type;
 						if (!left.empty())
-							ss << sp << left;
+							ss << left;
 						mCandidate = ss.str();
 						break;
 					}

src/description.cpp

@@ -109,13 +109,12 @@ void Description::setFingerprint(string fingerprint) {
 
 void Description::setSctpPort(uint16_t port) { mSctpPort.emplace(port); }
 
-void Description::addCandidate(std::optional<Candidate> candidate) {
-	if (candidate)
-		mCandidates.emplace_back(std::move(*candidate));
-	else
-		mTrickle = false;
+void Description::addCandidate(Candidate candidate) {
+	mCandidates.emplace_back(std::move(candidate));
 }
 
+void Description::endCandidates() { mTrickle = false; }
+
 Description::operator string() const {
 	if (!mFingerprint)
 		throw std::logic_error("Fingerprint must be set to generate a SDP");

src/dtlstransport.cpp

@@ -22,6 +22,7 @@
 #include <cassert>
 #include <cstring>
 #include <exception>
+#include <iostream>
 
 #include <gnutls/dtls.h>
 
@@ -46,9 +47,11 @@ namespace rtc {
 using std::shared_ptr;
 
 DtlsTransport::DtlsTransport(shared_ptr<IceTransport> lower, shared_ptr<Certificate> certificate,
-                             verifier_callback verifier, ready_callback ready)
-    : Transport(lower), mCertificate(certificate), mVerifierCallback(std::move(verifier)),
-      mReadyCallback(std::move(ready)) {
+                             verifier_callback verifierCallback,
+                             state_callback stateChangeCallback)
+    : Transport(lower), mCertificate(certificate), mState(State::Disconnected),
+      mVerifierCallback(std::move(verifierCallback)),
+      mStateChangeCallback(std::move(stateChangeCallback)) {
 	gnutls_certificate_set_verify_function(mCertificate->credentials(), CertificateCallback);
 
 	bool active = lower->role() == Description::Role::Active;
@@ -81,7 +84,12 @@ DtlsTransport::~DtlsTransport() {
 	gnutls_deinit(mSession);
 }
 
+DtlsTransport::State DtlsTransport::state() const { return mState; }
+
 bool DtlsTransport::send(message_ptr message) {
+	if (!message)
+		return false;
+
 	while (true) {
 		ssize_t ret = gnutls_record_send(mSession, message->data(), message->size());
 		if (check_gnutls(ret)) {
@@ -92,10 +100,25 @@ bool DtlsTransport::send(message_ptr message) {
 
 void DtlsTransport::incoming(message_ptr message) { mIncomingQueue.push(message); }
 
-void DtlsTransport::runRecvLoop() {
-	while (!check_gnutls(gnutls_handshake(mSession), "TLS handshake failed")) {}
+void DtlsTransport::changeState(State state) {
+	mState = state;
+	mStateChangeCallback(state);
+}
 
-	mReadyCallback();
+void DtlsTransport::runRecvLoop() {
+	try {
+		changeState(State::Connecting);
+
+		while (!check_gnutls(gnutls_handshake(mSession), "TLS handshake failed")) {
+		}
+	} catch (const std::exception &e) {
+		std::cerr << "DTLS handshake: " << e.what() << std::endl;
+		changeState(State::Failed);
+		return;
+	}
+
+	try {
+		changeState(State::Connected);
 
 		const size_t bufferSize = 2048;
 		char buffer[bufferSize];
@@ -111,6 +134,13 @@ void DtlsTransport::runRecvLoop() {
 				recv(make_message(b, b + ret));
 			}
 		}
+
+	} catch (const std::exception &e) {
+		std::cerr << "DTLS recv: " << e.what() << std::endl;
+	}
+
+	changeState(State::Disconnected);
+	recv(nullptr);
 }
 
 int DtlsTransport::CertificateCallback(gnutls_session_t session) {
@@ -120,7 +150,6 @@ int DtlsTransport::CertificateCallback(gnutls_session_t session) {
 		return GNUTLS_E_CERTIFICATE_ERROR;
 	}
 
-	// Get peer's certificate
 	unsigned int count = 0;
 	const gnutls_datum_t *array = gnutls_certificate_get_peers(session, &count);
 	if (!array || count == 0) {
@@ -155,13 +184,13 @@ ssize_t DtlsTransport::WriteCallback(gnutls_transport_ptr_t ptr, const void *dat
 ssize_t DtlsTransport::ReadCallback(gnutls_transport_ptr_t ptr, void *data, size_t maxlen) {
 	DtlsTransport *t = static_cast<DtlsTransport *>(ptr);
 	auto next = t->mIncomingQueue.pop();
-	if (!next) {
+	auto message = next ? *next : nullptr;
+	if (!message) {
 		// Closed
 		gnutls_transport_set_errno(t->mSession, 0);
 		return 0;
 	}
 
-	auto message = *next;
 	ssize_t len = std::min(maxlen, message->size());
 	std::memcpy(data, message->data(), len);
 	gnutls_transport_set_errno(t->mSession, 0);

src/dtlstransport.hpp

@@ -25,6 +25,7 @@
 #include "queue.hpp"
 #include "transport.hpp"
 
+#include <atomic>
 #include <functional>
 #include <memory>
 #include <thread>
@@ -37,26 +38,33 @@ class IceTransport;
 
 class DtlsTransport : public Transport {
 public:
+	enum class State { Disconnected, Connecting, Connected, Failed };
+
 	using verifier_callback = std::function<bool(const std::string &fingerprint)>;
-	using ready_callback = std::function<void(void)>;
+	using state_callback = std::function<void(State state)>;
 
 	DtlsTransport(std::shared_ptr<IceTransport> lower, std::shared_ptr<Certificate> certificate,
-	              verifier_callback verifier, ready_callback ready);
+	              verifier_callback verifierCallback, state_callback stateChangeCallback);
 	~DtlsTransport();
 
+	State state() const;
+
 	bool send(message_ptr message);
 
 private:
 	void incoming(message_ptr message);
+	void changeState(State state);
 	void runRecvLoop();
 
 	const std::shared_ptr<Certificate> mCertificate;
 
 	gnutls_session_t mSession;
 	Queue<message_ptr> mIncomingQueue;
+	std::atomic<State> mState;
 	std::thread mRecvThread;
+
 	verifier_callback mVerifierCallback;
-	ready_callback mReadyCallback;
+	state_callback mStateChangeCallback;
 
 	static int CertificateCallback(gnutls_session_t session);
 	static ssize_t WriteCallback(gnutls_transport_ptr_t ptr, const void *data, size_t len);

src/icetransport.cpp

@@ -34,10 +34,14 @@ using std::shared_ptr;
 using std::weak_ptr;
 
 IceTransport::IceTransport(const Configuration &config, Description::Role role,
-                           candidate_callback candidateCallback, ready_callback ready)
-    : mRole(role), mMid("0"), mState(State::Disconnected), mNiceAgent(nullptr, nullptr),
-      mMainLoop(nullptr, nullptr), mCandidateCallback(std::move(candidateCallback)),
-      mReadyCallback(ready) {
+                           candidate_callback candidateCallback,
+                           state_callback stateChangeCallback,
+                           gathering_state_callback gatheringStateChangeCallback)
+    : mRole(role), mMid("0"), mState(State::Disconnected), mGatheringState(GatheringState::New),
+      mNiceAgent(nullptr, nullptr), mMainLoop(nullptr, nullptr),
+      mCandidateCallback(std::move(candidateCallback)),
+      mStateChangeCallback(std::move(stateChangeCallback)),
+      mGatheringStateChangeCallback(std::move(gatheringStateChangeCallback)) {
 
 	auto logLevelFlags = GLogLevelFlags(G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL | G_LOG_FLAG_RECURSION);
 	g_log_set_handler(nullptr, logLevelFlags, LogCallback, this);
@@ -102,7 +106,7 @@ IceTransport::IceTransport(const Configuration &config, Description::Role role,
 	}
 
 	g_signal_connect(G_OBJECT(mNiceAgent.get()), "component-state-changed",
-	                 G_CALLBACK(StateChangedCallback), this);
+	                 G_CALLBACK(StateChangeCallback), this);
 	g_signal_connect(G_OBJECT(mNiceAgent.get()), "new-candidate-full",
 	                 G_CALLBACK(CandidateCallback), this);
 	g_signal_connect(G_OBJECT(mNiceAgent.get()), "candidate-gathering-done",
@@ -146,9 +150,13 @@ void IceTransport::setRemoteDescription(const Description &description) {
 }
 
 void IceTransport::gatherLocalCandidates() {
-	if (!nice_agent_gather_candidates(mNiceAgent.get(), mStreamId))
+	// Change state now as candidates calls can be synchronous
+	changeGatheringState(GatheringState::InProgress);
+
+	if (!nice_agent_gather_candidates(mNiceAgent.get(), mStreamId)) {
 		throw std::runtime_error("Failed to gather local ICE candidates");
 	}
+}
 
 bool IceTransport::addRemoteCandidate(const Candidate &candidate) {
 	// Warning: the candidate string must start with "a=candidate:" and it must not end with a
@@ -167,7 +175,7 @@ bool IceTransport::addRemoteCandidate(const Candidate &candidate) {
 }
 
 bool IceTransport::send(message_ptr message) {
-	if (!mStreamId)
+	if (!message || !mStreamId)
 		return false;
 
 	outgoing(message);
@@ -185,42 +193,66 @@ void IceTransport::outgoing(message_ptr message) {
 	                reinterpret_cast<const char *>(message->data()));
 }
 
+void IceTransport::changeState(State state) {
+	mState = state;
+	mStateChangeCallback(mState);
+}
+
+void IceTransport::changeGatheringState(GatheringState state) {
+	mGatheringState = state;
+	mGatheringStateChangeCallback(mGatheringState);
+}
+
 void IceTransport::processCandidate(const string &candidate) {
 	mCandidateCallback(Candidate(candidate, mMid));
 }
 
-void IceTransport::processGatheringDone() { mCandidateCallback(nullopt); }
+void IceTransport::processGatheringDone() { changeGatheringState(GatheringState::Complete); }
 
-void IceTransport::changeState(uint32_t state) {
-	mState = static_cast<State>(state);
-	if (mState == State::Ready) {
-		mReadyCallback();
-	}
+void IceTransport::processStateChange(uint32_t state) {
+	if (state != NICE_COMPONENT_STATE_GATHERING)
+		changeState(static_cast<State>(state));
 }
 
 void IceTransport::CandidateCallback(NiceAgent *agent, NiceCandidate *candidate,
                                      gpointer userData) {
 	auto iceTransport = static_cast<rtc::IceTransport *>(userData);
 	gchar *cand = nice_agent_generate_local_candidate_sdp(agent, candidate);
+	try {
 		iceTransport->processCandidate(cand);
+	} catch (const std::exception &e) {
+		std::cerr << "ICE candidate: " << e.what() << std::endl;
+	}
 	g_free(cand);
 }
 
 void IceTransport::GatheringDoneCallback(NiceAgent *agent, guint streamId, gpointer userData) {
 	auto iceTransport = static_cast<rtc::IceTransport *>(userData);
+	try {
 		iceTransport->processGatheringDone();
+	} catch (const std::exception &e) {
+		std::cerr << "ICE gathering done: " << e.what() << std::endl;
+	}
 }
 
-void IceTransport::StateChangedCallback(NiceAgent *agent, guint streamId, guint componentId,
+void IceTransport::StateChangeCallback(NiceAgent *agent, guint streamId, guint componentId,
                                         guint state, gpointer userData) {
 	auto iceTransport = static_cast<rtc::IceTransport *>(userData);
-	iceTransport->changeState(state);
+	try {
+		iceTransport->processStateChange(state);
+	} catch (const std::exception &e) {
+		std::cerr << "ICE change state: " << e.what() << std::endl;
+	}
 }
 
 void IceTransport::RecvCallback(NiceAgent *agent, guint streamId, guint componentId, guint len,
                                 gchar *buf, gpointer userData) {
 	auto iceTransport = static_cast<rtc::IceTransport *>(userData);
+	try {
 		iceTransport->incoming(reinterpret_cast<byte *>(buf), len);
+	} catch (const std::exception &e) {
+		std::cerr << "ICE incoming: " << e.what() << std::endl;
+	}
 }
 
 void IceTransport::LogCallback(const gchar *logDomain, GLogLevelFlags logLevel,

src/icetransport.hpp

@@ -31,7 +31,6 @@ extern "C" {
 }
 
 #include <atomic>
-#include <optional>
 #include <thread>
 
 namespace rtc {
@@ -40,22 +39,26 @@ class IceTransport : public Transport {
 public:
 	enum class State : uint32_t {
 		Disconnected = NICE_COMPONENT_STATE_DISCONNECTED,
-		Gathering = NICE_COMPONENT_STATE_GATHERING,
 		Connecting = NICE_COMPONENT_STATE_CONNECTING,
 		Connected = NICE_COMPONENT_STATE_CONNECTED,
 		Ready = NICE_COMPONENT_STATE_READY,
 		Failed = NICE_COMPONENT_STATE_FAILED
 	};
 
-	using candidate_callback = std::function<void(const std::optional<Candidate> &candidate)>;
-	using ready_callback = std::function<void(void)>;
+	enum class GatheringState { New = 0, InProgress = 1, Complete = 2 };
+
+	using candidate_callback = std::function<void(const Candidate &candidate)>;
+	using state_callback = std::function<void(State state)>;
+	using gathering_state_callback = std::function<void(GatheringState state)>;
 
 	IceTransport(const Configuration &config, Description::Role role,
-	             candidate_callback candidateCallback, ready_callback ready);
+	             candidate_callback candidateCallback, state_callback stateChangeCallback,
+	             gathering_state_callback gatheringStateChangeCallback);
 	~IceTransport();
 
 	Description::Role role() const;
 	State state() const;
+	GatheringState gyyatheringState() const;
 	Description getLocalDescription(Description::Type type) const;
 	void setRemoteDescription(const Description &description);
 	void gatherLocalCandidates();
@@ -68,13 +71,17 @@ private:
 	void incoming(const byte *data, int size);
 	void outgoing(message_ptr message);
 
-	void changeState(uint32_t state);
+	void changeState(State state);
+	void changeGatheringState(GatheringState state);
+
 	void processCandidate(const string &candidate);
 	void processGatheringDone();
+	void processStateChange(uint32_t state);
 
 	Description::Role mRole;
 	string mMid;
-	State mState;
+	std::atomic<State> mState;
+	std::atomic<GatheringState> mGatheringState;
 
 	uint32_t mStreamId = 0;
 	std::unique_ptr<NiceAgent, void (*)(gpointer)> mNiceAgent;
@@ -82,11 +89,12 @@ private:
 	std::thread mMainLoopThread;
 
 	candidate_callback mCandidateCallback;
-	ready_callback mReadyCallback;
+	state_callback mStateChangeCallback;
+	gathering_state_callback mGatheringStateChangeCallback;
 
 	static void CandidateCallback(NiceAgent *agent, NiceCandidate *candidate, gpointer userData);
 	static void GatheringDoneCallback(NiceAgent *agent, guint streamId, gpointer userData);
-	static void StateChangedCallback(NiceAgent *agent, guint streamId, guint componentId,
+	static void StateChangeCallback(NiceAgent *agent, guint streamId, guint componentId,
 	                                 guint state, gpointer userData);
 	static void RecvCallback(NiceAgent *agent, guint stream_id, guint component_id, guint len,
 	                         gchar *buf, gpointer userData);

src/peerconnection.cpp

@@ -34,12 +34,16 @@ using std::shared_ptr;
 PeerConnection::PeerConnection() : PeerConnection(Configuration()) {}
 
 PeerConnection::PeerConnection(const Configuration &config)
-    : mConfig(config), mCertificate(make_certificate("libdatachannel")) {}
+    : mConfig(config), mCertificate(make_certificate("libdatachannel")), mState(State::New) {}
 
 PeerConnection::~PeerConnection() {}
 
 const Configuration *PeerConnection::config() const { return &mConfig; }
 
+PeerConnection::State PeerConnection::state() const { return mState; }
+
+PeerConnection::GatheringState PeerConnection::gatheringState() const { return mGatheringState; }
+
 std::optional<Description> PeerConnection::localDescription() const { return mLocalDescription; }
 
 std::optional<Description> PeerConnection::remoteDescription() const { return mRemoteDescription; }
@@ -62,9 +66,7 @@ void PeerConnection::addRemoteCandidate(Candidate candidate) {
 		throw std::logic_error("Remote candidate set without remote description");
 
 	if (mIceTransport->addRemoteCandidate(candidate))
-		mRemoteDescription->addCandidate(std::make_optional(std::move(candidate)));
-	else
-		std::cerr << "Failed to add remote ICE candidate" << std::endl;
+		mRemoteDescription->addCandidate(std::move(candidate));
 }
 
 shared_ptr<DataChannel> PeerConnection::createDataChannel(const string &label,
@@ -88,7 +90,7 @@ shared_ptr<DataChannel> PeerConnection::createDataChannel(const string &label,
 		initIceTransport(Description::Role::Active);
 		processLocalDescription(mIceTransport->getLocalDescription(Description::Type::Offer));
 		mIceTransport->gatherLocalCandidates();
-	} else if (mSctpTransport && mSctpTransport->isReady()) {
+	} else if (mSctpTransport && mSctpTransport->state() == SctpTransport::State::Connected) {
 		channel->open(mSctpTransport);
 	}
 	return channel;
@@ -104,28 +106,93 @@ void PeerConnection::onLocalDescription(
 	mLocalDescriptionCallback = callback;
 }
 
-void PeerConnection::onLocalCandidate(
-    std::function<void(const std::optional<Candidate> &candidate)> callback) {
+void PeerConnection::onLocalCandidate(std::function<void(const Candidate &candidate)> callback) {
 	mLocalCandidateCallback = callback;
 }
 
+void PeerConnection::onStateChange(std::function<void(State state)> callback) {
+	mStateChangeCallback = callback;
+}
+
+void PeerConnection::onGatheringStateChange(std::function<void(GatheringState state)> callback) {
+	mGatheringStateChangeCallback = callback;
+}
+
 void PeerConnection::initIceTransport(Description::Role role) {
 	mIceTransport = std::make_shared<IceTransport>(
 	    mConfig, role, std::bind(&PeerConnection::processLocalCandidate, this, _1),
-	    std::bind(&PeerConnection::initDtlsTransport, this));
+	    [this](IceTransport::State state) {
+		    switch (state) {
+		    case IceTransport::State::Connecting:
+			    changeState(State::Connecting);
+			    break;
+		    case IceTransport::State::Failed:
+			    changeState(State::Failed);
+			    break;
+		    case IceTransport::State::Ready:
+			    initDtlsTransport();
+			    break;
+		    default:
+			    // Ignore
+			    break;
+		    }
+	    },
+	    [this](IceTransport::GatheringState state) {
+		    switch (state) {
+		    case IceTransport::GatheringState::InProgress:
+			    changeGatheringState(GatheringState::InProgress);
+			    break;
+		    case IceTransport::GatheringState::Complete:
+			    if (mLocalDescription)
+				    mLocalDescription->endCandidates();
+			    changeGatheringState(GatheringState::Complete);
+			    break;
+		    default:
+			    // Ignore
+			    break;
+		    }
+	    });
 }
 
 void PeerConnection::initDtlsTransport() {
 	mDtlsTransport = std::make_shared<DtlsTransport>(
 	    mIceTransport, mCertificate, std::bind(&PeerConnection::checkFingerprint, this, _1),
-	    std::bind(&PeerConnection::initSctpTransport, this));
+	    [this](DtlsTransport::State state) {
+		    switch (state) {
+		    case DtlsTransport::State::Connected:
+			    initSctpTransport();
+			    break;
+		    case DtlsTransport::State::Failed:
+			    changeState(State::Failed);
+			    break;
+		    default:
+			    // Ignore
+			    break;
+		    }
+	    });
 }
 
 void PeerConnection::initSctpTransport() {
 	uint16_t sctpPort = mRemoteDescription->sctpPort().value_or(DEFAULT_SCTP_PORT);
 	mSctpTransport = std::make_shared<SctpTransport>(
-	    mDtlsTransport, sctpPort, std::bind(&PeerConnection::openDataChannels, this),
-	    std::bind(&PeerConnection::forwardMessage, this, _1));
+	    mDtlsTransport, sctpPort, std::bind(&PeerConnection::forwardMessage, this, _1),
+	    [this](SctpTransport::State state) {
+		    switch (state) {
+		    case SctpTransport::State::Connected:
+			    changeState(State::Connected);
+			    openDataChannels();
+			    break;
+		    case SctpTransport::State::Failed:
+			    changeState(State::Failed);
+			    break;
+		    case SctpTransport::State::Disconnected:
+			    changeState(State::Disconnected);
+			    break;
+		    default:
+			    // Ignore
+			    break;
+		    }
+	    });
 }
 
 bool PeerConnection::checkFingerprint(const std::string &fingerprint) const {
@@ -140,6 +207,11 @@ void PeerConnection::forwardMessage(message_ptr message) {
 	if (!mIceTransport || !mSctpTransport)
 		throw std::logic_error("Got a DataChannel message without transport");
 
+	if (!message) {
+		closeDataChannels();
+		return;
+	}
+
 	shared_ptr<DataChannel> channel;
 	if (auto it = mDataChannels.find(message->stream); it != mDataChannels.end()) {
 		channel = it->second.lock();
@@ -167,7 +239,8 @@ void PeerConnection::forwardMessage(message_ptr message) {
 	channel->incoming(message);
 }
 
-void PeerConnection::openDataChannels(void) {
+void PeerConnection::iterateDataChannels(
+    std::function<void(shared_ptr<DataChannel> channel)> func) {
 	auto it = mDataChannels.begin();
 	while (it != mDataChannels.end()) {
 		auto channel = it->second.lock();
@@ -175,11 +248,19 @@ void PeerConnection::openDataChannels(void) {
 			it = mDataChannels.erase(it);
 			continue;
 		}
-		channel->open(mSctpTransport);
+		func(channel);
 		++it;
 	}
 }
 
+void PeerConnection::openDataChannels() {
+	iterateDataChannels([this](shared_ptr<DataChannel> channel) { channel->open(mSctpTransport); });
+}
+
+void PeerConnection::closeDataChannels() {
+	iterateDataChannels([](shared_ptr<DataChannel> channel) { channel->close(); });
+}
+
 void PeerConnection::processLocalDescription(Description description) {
 	auto remoteSctpPort = mRemoteDescription ? mRemoteDescription->sctpPort() : nullopt;
 
@@ -191,7 +272,7 @@ void PeerConnection::processLocalDescription(Description description) {
 		mLocalDescriptionCallback(*mLocalDescription);
 }
 
-void PeerConnection::processLocalCandidate(std::optional<Candidate> candidate) {
+void PeerConnection::processLocalCandidate(Candidate candidate) {
 	if (!mLocalDescription)
 		throw std::logic_error("Got a local candidate without local description");
 
@@ -206,4 +287,63 @@ void PeerConnection::triggerDataChannel(std::shared_ptr<DataChannel> dataChannel
 		mDataChannelCallback(dataChannel);
 }
 
+void PeerConnection::changeState(State state) {
+	mState = state;
+	if (mStateChangeCallback)
+		mStateChangeCallback(state);
+}
+
+void PeerConnection::changeGatheringState(GatheringState state) {
+	mGatheringState = state;
+	if (mGatheringStateChangeCallback)
+		mGatheringStateChangeCallback(state);
+}
+
 } // namespace rtc
+
+std::ostream &operator<<(std::ostream &out, const rtc::PeerConnection::State &state) {
+	using State = rtc::PeerConnection::State;
+	std::string str;
+	switch (state) {
+	case State::New:
+		str = "new";
+		break;
+	case State::Connecting:
+		str = "connecting";
+		break;
+	case State::Connected:
+		str = "connected";
+		break;
+	case State::Disconnected:
+		str = "disconnected";
+		break;
+	case State::Failed:
+		str = "failed";
+		break;
+	default:
+		str = "unknown";
+		break;
+	}
+	return out << str;
+}
+
+std::ostream &operator<<(std::ostream &out, const rtc::PeerConnection::GatheringState &state) {
+	using GatheringState = rtc::PeerConnection::GatheringState;
+	std::string str;
+	switch (state) {
+	case GatheringState::New:
+		str = "new";
+		break;
+	case GatheringState::InProgress:
+		str = "in_progress";
+		break;
+	case GatheringState::Complete:
+		str = "complete";
+		break;
+	default:
+		str = "unknown";
+		break;
+	}
+	return out << str;
+}
+

src/rtc.cpp

@@ -95,14 +95,32 @@ void rtcSetLocalCandidateCallback(int pc,
 	if (it == peerConnectionMap.end())
 		return;
 
-	it->second->onLocalCandidate(
-	    [pc, candidateCallback](const std::optional<Candidate> &candidate) {
-		    if (candidate) {
-			    candidateCallback(string(*candidate).c_str(), candidate->mid().c_str(),
+	it->second->onLocalCandidate([pc, candidateCallback](const Candidate &candidate) {
+		candidateCallback(candidate.candidate().c_str(), candidate.mid().c_str(),
 		                  getUserPointer(pc));
-		    } else {
-			    candidateCallback(nullptr, nullptr, getUserPointer(pc));
+	});
 }
+
+void rtcSetStateChangeCallback(int pc, void (*stateCallback)(rtc_state_t state, void *)) {
+	auto it = peerConnectionMap.find(pc);
+	if (it == peerConnectionMap.end())
+		return;
+
+	it->second->onStateChange([pc, stateCallback](PeerConnection::State state) {
+		stateCallback(static_cast<rtc_state_t>(state), getUserPointer(pc));
+	});
+}
+
+void rtcSetGatheringStateChangeCallback(int pc,
+                                         void (*gatheringStateCallback)(rtc_gathering_state_t state,
+                                                                        void *)) {
+	auto it = peerConnectionMap.find(pc);
+	if (it == peerConnectionMap.end())
+		return;
+
+	it->second->onGatheringStateChange(
+	    [pc, gatheringStateCallback](PeerConnection::GatheringState state) {
+		    gatheringStateCallback(static_cast<rtc_gathering_state_t>(state), getUserPointer(pc));
 	    });
 }
 

src/sctptransport.cpp

@@ -47,9 +47,10 @@ void SctpTransport::GlobalCleanup() {
 	}
 }
 
-SctpTransport::SctpTransport(std::shared_ptr<Transport> lower, uint16_t port, ready_callback ready,
-                             message_callback recv)
-    : Transport(lower), mReadyCallback(std::move(ready)), mPort(port) {
+SctpTransport::SctpTransport(std::shared_ptr<Transport> lower, uint16_t port, message_callback recv,
+                             state_callback stateChangeCallback)
+    : Transport(lower), mPort(port), mState(State::Disconnected),
+      mStateChangeCallback(std::move(stateChangeCallback)) {
 
 	onRecv(recv);
 
@@ -120,6 +121,7 @@ SctpTransport::SctpTransport(std::shared_ptr<Transport> lower, uint16_t port, re
 
 SctpTransport::~SctpTransport() {
 	mStopping = true;
+	mConnectCondition.notify_all();
 	if (mConnectThread.joinable())
 		mConnectThread.join();
 
@@ -132,9 +134,12 @@ SctpTransport::~SctpTransport() {
 	GlobalCleanup();
 }
 
-bool SctpTransport::isReady() const { return mIsReady; }
+SctpTransport::State SctpTransport::state() const { return mState; }
 
 bool SctpTransport::send(message_ptr message) {
+	if (!message)
+		return false;
+
 	const Reliability reliability = message->reliability ? *message->reliability : Reliability();
 
 	struct sctp_sendv_spa spa = {};
@@ -201,6 +206,12 @@ void SctpTransport::reset(unsigned int stream) {
 }
 
 void SctpTransport::incoming(message_ptr message) {
+	if (!message) {
+		changeState(State::Disconnected);
+		recv(nullptr);
+		return;
+	}
+
 	// There could be a race condition here where we receive the remote INIT before the thread in
 	// usrsctp_connect sends the local one, which would result in the connection being aborted.
 	// Therefore, we need to wait for data to be sent on our side (i.e. the local INIT) before
@@ -214,7 +225,15 @@ void SctpTransport::incoming(message_ptr message) {
 		usrsctp_conninput(this, message->data(), message->size(), 0);
 }
 
+void SctpTransport::changeState(State state) {
+	mState = state;
+	mStateChangeCallback(state);
+}
+
 void SctpTransport::runConnect() {
+	try {
+		changeState(State::Connecting);
+
 		struct sockaddr_conn sconn = {};
 		sconn.sconn_family = AF_CONN;
 		sconn.sconn_port = htons(mPort);
@@ -226,15 +245,19 @@ void SctpTransport::runConnect() {
 		// According to the IETF draft, both endpoints must initiate the SCTP association, in a
 		// simultaneous-open manner, irrelevent to the SDP setup role.
 		// See https://tools.ietf.org/html/draft-ietf-mmusic-sctp-sdp-26#section-9.3
-	if (usrsctp_connect(mSock, reinterpret_cast<struct sockaddr *>(&sconn), sizeof(sconn)) != 0) {
+		if (usrsctp_connect(mSock, reinterpret_cast<struct sockaddr *>(&sconn), sizeof(sconn)) !=
+		    0) {
 			std::cerr << "SCTP connection failed, errno=" << errno << std::endl;
+			changeState(State::Failed);
 			mStopping = true;
 			return;
 		}
 
-	if (!mStopping) {
-		mIsReady = true;
-		mReadyCallback();
+		if (!mStopping)
+			changeState(State::Connected);
+
+	} catch (const std::exception &e) {
+		std::cerr << "SCTP connect: " << e.what() << std::endl;
 	}
 }
 
@@ -251,12 +274,11 @@ int SctpTransport::handleWrite(void *data, size_t len, uint8_t tos, uint8_t set_
 }
 
 int SctpTransport::process(struct socket *sock, union sctp_sockstore addr, void *data, size_t len,
-                           struct sctp_rcvinfo recv_info, int flags) {
+                           struct sctp_rcvinfo info, int flags) {
 	if (flags & MSG_NOTIFICATION) {
 		processNotification((union sctp_notification *)data, len);
 	} else {
-		processData((const byte *)data, len, recv_info.rcv_sid,
-		            PayloadId(htonl(recv_info.rcv_ppid)));
+		processData((const byte *)data, len, info.rcv_sid, PayloadId(htonl(info.rcv_ppid)));
 	}
 	free(data);
 	return 0;

src/sctptransport.hpp

@@ -36,13 +36,15 @@ namespace rtc {
 
 class SctpTransport : public Transport {
 public:
-	using ready_callback = std::function<void(void)>;
+	enum class State { Disconnected, Connecting, Connected, Failed };
 
-	SctpTransport(std::shared_ptr<Transport> lower, uint16_t port, ready_callback ready,
-	              message_callback recv);
+	using state_callback = std::function<void(State state)>;
+
+	SctpTransport(std::shared_ptr<Transport> lower, uint16_t port, message_callback recv,
+	              state_callback stateChangeCallback);
 	~SctpTransport();
 
-	bool isReady() const;
+	State state() const;
 
 	bool send(message_ptr message);
 	void reset(unsigned int stream);
@@ -57,6 +59,7 @@ private:
 	};
 
 	void incoming(message_ptr message);
+	void changeState(State state);
 	void runConnect();
 
 	int handleWrite(void *data, size_t len, uint8_t tos, uint8_t set_df);
@@ -67,18 +70,18 @@ private:
 	void processData(const byte *data, size_t len, uint16_t streamId, PayloadId ppid);
 	void processNotification(const union sctp_notification *notify, size_t len);
 
-	ready_callback mReadyCallback;
-
 	struct socket *mSock;
 	uint16_t mPort;
 
 	std::thread mConnectThread;
-	std::atomic<bool> mStopping = false;
-	std::atomic<bool> mIsReady = false;
-
 	std::mutex mConnectMutex;
 	std::condition_variable mConnectCondition;
 	std::atomic<bool> mConnectDataSent = false;
+	std::atomic<bool> mStopping = false;
+
+	std::atomic<State> mState;
+
+	state_callback mStateChangeCallback;
 
 	static int WriteCallback(void *sctp_ptr, void *data, size_t len, uint8_t tos, uint8_t set_df);
 	static int ReadCallback(struct socket *sock, union sctp_sockstore addr, void *data, size_t len,

test/main.cpp

@@ -27,19 +27,25 @@ using namespace rtc;
 using namespace std;
 
 int main(int argc, char **argv) {
-	auto pc1 = std::make_shared<PeerConnection>();
-	auto pc2 = std::make_shared<PeerConnection>();
+	rtc::Configuration config;
+	// config.iceServers.emplace_back("stun.l.google.com:19302");
+
+	auto pc1 = std::make_shared<PeerConnection>(config);
+	auto pc2 = std::make_shared<PeerConnection>(config);
 
 	pc1->onLocalDescription([pc2](const Description &sdp) {
 		cout << "Description 1: " << sdp << endl;
 		pc2->setRemoteDescription(sdp);
 	});
 
-	pc1->onLocalCandidate([pc2](const optional<Candidate> &candidate) {
-		if (candidate) {
-			cout << "Candidate 1: " << *candidate << endl;
-			pc2->addRemoteCandidate(*candidate);
-		}
+	pc1->onLocalCandidate([pc2](const Candidate &candidate) {
+		cout << "Candidate 1: " << candidate << endl;
+		pc2->addRemoteCandidate(candidate);
+	});
+
+	pc1->onStateChange([](PeerConnection::State state) { cout << "State 1: " << state << endl; });
+	pc1->onGatheringStateChange([](PeerConnection::GatheringState state) {
+		cout << "Gathering state 1: " << state << endl;
 	});
 
 	pc2->onLocalDescription([pc1](const Description &sdp) {
@@ -47,11 +53,14 @@ int main(int argc, char **argv) {
 		pc1->setRemoteDescription(sdp);
 	});
 
-	pc2->onLocalCandidate([pc1](const optional<Candidate> &candidate) {
-		if (candidate) {
-			cout << "Candidate 2: " << *candidate << endl;
-			pc1->addRemoteCandidate(*candidate);
-		}
+	pc2->onLocalCandidate([pc1](const Candidate &candidate) {
+		cout << "Candidate 2: " << candidate << endl;
+		pc1->addRemoteCandidate(candidate);
+	});
+
+	pc2->onStateChange([](PeerConnection::State state) { cout << "State 2: " << state << endl; });
+	pc2->onGatheringStateChange([](PeerConnection::GatheringState state) {
+		cout << "Gathering state 2: " << state << endl;
 	});
 
 	shared_ptr<DataChannel> dc2;