feat: add remoteFingerprints method to PeerConnection

include/rtc/peerconnection.hpp

@@ -113,6 +113,7 @@ class RTC_CPP_EXPORT PeerConnection final : CheshireCat<impl::PeerConnection> {
 	void onSignalingStateChange(std::function<void(SignalingState state)> callback);
 
 	void resetCallbacks();
+	CertificateFingerprint remoteFingerprint();
 
 	// Stats
 	void clearStats();

src/impl/peerconnection.cpp

@@ -234,6 +234,8 @@ shared_ptr<DtlsTransport> PeerConnection::initDtlsTransport() {
 			fingerprintAlgorithm = remote->fingerprint()->algorithm;
 		}
 
+		mRemoteFingerprintAlgorithm = fingerprintAlgorithm;
+
 		auto lower = std::atomic_load(&mIceTransport);
 		if (!lower)
 			throw std::logic_error("No underlying ICE transport for DTLS transport");
@@ -439,17 +441,21 @@ void PeerConnection::rollbackLocalDescription() {
 	}
 }
 
-bool PeerConnection::checkFingerprint(const std::string &fingerprint) const {
+bool PeerConnection::checkFingerprint(const std::string &fingerprint) {
 	std::lock_guard lock(mRemoteDescriptionMutex);
 	if (!mRemoteDescription || !mRemoteDescription->fingerprint())
 		return false;
 
-	if (config.disableFingerprintVerification)
+  if (config.disableFingerprintVerification) {
+		PLOG_VERBOSE << "Skipping fingerprint validation";
+		mRemoteFingerprint = fingerprint;
 		return true;
+	}
 
 	auto expectedFingerprint = mRemoteDescription->fingerprint()->value;
-	if (expectedFingerprint  == fingerprint) {
+	if (expectedFingerprint == fingerprint) {
 		PLOG_VERBOSE << "Valid fingerprint \"" << fingerprint << "\"";
+		mRemoteFingerprint = fingerprint;
 		return true;
 	}
 
@@ -1301,6 +1307,13 @@ void PeerConnection::resetCallbacks() {
 	trackCallback = nullptr;
 }
 
+CertificateFingerprint PeerConnection::remoteFingerprint() {
+	if (mRemoteFingerprint)
+		return {CertificateFingerprint{mRemoteFingerprintAlgorithm, *mRemoteFingerprint}};
+	else
+		return {};
+}
+
 void PeerConnection::updateTrackSsrcCache(const Description &description) {
 	std::unique_lock lock(mTracksMutex); // for safely writing to mTracksBySsrc
 

src/impl/peerconnection.hpp

@@ -53,7 +53,7 @@ struct PeerConnection : std::enable_shared_from_this<PeerConnection> {
 
 	void endLocalCandidates();
 	void rollbackLocalDescription();
-	bool checkFingerprint(const std::string &fingerprint) const;
+	bool checkFingerprint(const std::string &fingerprint);
 	void forwardMessage(message_ptr message);
 	void forwardMedia(message_ptr message);
 	void forwardBufferedAmount(uint16_t stream, size_t amount);
@@ -98,6 +98,7 @@ struct PeerConnection : std::enable_shared_from_this<PeerConnection> {
 	bool changeSignalingState(SignalingState newState);
 
 	void resetCallbacks();
+	CertificateFingerprint remoteFingerprint();
 
 	// Helper method for asynchronous callback invocation
 	template <typename... Args> void trigger(synchronized_callback<Args...> *cb, Args... args) {
@@ -157,6 +158,9 @@ struct PeerConnection : std::enable_shared_from_this<PeerConnection> {
 
 	Queue<shared_ptr<DataChannel>> mPendingDataChannels;
 	Queue<shared_ptr<Track>> mPendingTracks;
+
+	CertificateFingerprint::Algorithm mRemoteFingerprintAlgorithm = CertificateFingerprint::Algorithm::Sha256;
+	optional<string> mRemoteFingerprint;
 };
 
 } // namespace rtc::impl

src/peerconnection.cpp

@@ -367,6 +367,10 @@ optional<std::chrono::milliseconds> PeerConnection::rtt() {
 	return sctpTransport ? sctpTransport->rtt() : nullopt;
 }
 
+CertificateFingerprint PeerConnection::remoteFingerprint() {
+	return impl()->remoteFingerprint();
+}
+
 std::ostream &operator<<(std::ostream &out, PeerConnection::State state) {
 	using State = PeerConnection::State;
 	const char *str;