STAR-1275: Read the peers SRT version and the negotiated latency from the socket

Pass a reference to a ConnectionInformation struct back to user
when a new client connects and the called connects to a server.

Author: Per Moberg

SRTNet.cpp

@@ -260,7 +260,8 @@ SRTNet::ClientConnectStatus SRTNet::clientConnectToServer() {
         if (result != SRT_ERROR) {
             mClientConnected = true;
             if (connectedToServer) {
-                connectedToServer(mConnectionContext, mContext);
+                ConnectionInformation connectionInformation = getConnectionInformation(mContext);
+                connectedToServer(mConnectionContext, mContext, connectionInformation);
             }
             // Break for-loop on first successful connect call
             break;
@@ -315,7 +316,9 @@ bool SRTNet::waitForSRTClient(bool singleClient) {
         }
 
         SRT_LOGGER(true, LOGG_NOTIFY, "Client connected: " << newSocketCandidate);
-        auto ctx = clientConnected(*reinterpret_cast<sockaddr*>(&theirAddr), newSocketCandidate, mConnectionContext);
+
+        ConnectionInformation connectionInformation = getConnectionInformation(newSocketCandidate);
+        auto ctx = clientConnected(*reinterpret_cast<sockaddr*>(&theirAddr), newSocketCandidate, mConnectionContext, connectionInformation);
 
         if (!ctx) {
             // No ctx in return from clientConnected callback means client was rejected by user.
@@ -948,3 +951,19 @@ uint16_t SRTNet::getLocallyBoundPort() const {
 
     return 0;
 }
+
+SRTNet::ConnectionInformation SRTNet::getConnectionInformation(SRTSOCKET socket) {
+    uint8_t clientSrtVersion[4];
+    int clientSrtVersionSize = sizeof(clientSrtVersion);
+    srt_getsockflag(socket, SRTO_PEERVERSION, &clientSrtVersion, &clientSrtVersionSize);
+
+    int32_t negotiatedLatency = 0;
+    int negotiatedLatencySize = sizeof(negotiatedLatency);
+    srt_getsockflag(socket, SRTO_PEERLATENCY, &negotiatedLatency, &negotiatedLatencySize);
+
+    ConnectionInformation connectionInformation;
+    connectionInformation.mPeerSrtVersion = std::string(std::to_string((int32_t)clientSrtVersion[2]) + "." + std::to_string((int32_t)clientSrtVersion[1]) + "." + std::to_string((int32_t)clientSrtVersion[0]));
+    connectionInformation.mNegotiatedLatency = negotiatedLatency;
+
+    return std::move(connectionInformation);
+}

SRTNet.h

@@ -60,6 +60,11 @@ class SRTNet {
         std::any mObject;
     };
 
+    struct ConnectionInformation {
+        std::string mPeerSrtVersion;
+        int32_t mNegotiatedLatency;
+    };
+
     /**
      *
      * @brief Constructor that can set a log prefix which will be added to the start of all log messages from this
@@ -288,7 +293,8 @@ class SRTNet {
     /// Callback handling connecting clients (only server mode)
     std::function<std::shared_ptr<NetworkConnection>(struct sockaddr& sin,
                                                      SRTSOCKET newSocket,
-                                                     std::shared_ptr<NetworkConnection>& ctx)>
+                                                     std::shared_ptr<NetworkConnection>& ctx,
+                                                     const ConnectionInformation& connectionInformation)>
         clientConnected = nullptr;
 
     /// Callback receiving data type vector
@@ -310,7 +316,7 @@ class SRTNet {
     std::function<void(std::shared_ptr<NetworkConnection>& ctx, SRTSOCKET lSocket)> clientDisconnected = nullptr;
 
     /// Callback called whenever the client gets connected to the server (client mode only)
-    std::function<void(std::shared_ptr<NetworkConnection>& ctx, SRTSOCKET lSocket)> connectedToServer = nullptr;
+    std::function<void(std::shared_ptr<NetworkConnection>& ctx, SRTSOCKET lSocket, const ConnectionInformation& connectionInformation)> connectedToServer = nullptr;
 
     // delete copy and move constructors and assign operators
     SRTNet(SRTNet const&) = delete;            // Copy construct
@@ -443,4 +449,5 @@ class SRTNet {
 
     const std::chrono::milliseconds kConnectionTimeout{1000};
     const int64_t kEpollTimeoutMs{500};
+    static ConnectionInformation getConnectionInformation(SRTSOCKET socket);
 };

test/TestSrt.cpp

@@ -79,7 +79,8 @@ class TestSRTFixture : public ::testing::Test {
 
         // notice when client connects to server
         mServer.clientConnected = [&](struct sockaddr& sin, SRTSOCKET newSocket,
-                                      std::shared_ptr<SRTNet::NetworkConnection>& ctx) {
+                                      std::shared_ptr<SRTNet::NetworkConnection>& ctx,
+                                      const SRTNet::ConnectionInformation&) {
             {
                 std::lock_guard<std::mutex> lock(mConnectedMutex);
                 mConnected = true;
@@ -150,7 +151,8 @@ TEST(TestSrt, StartStop) {
 
     // notice when client connects to server
     server.clientConnected = [&](struct sockaddr& sin, SRTSOCKET newSocket,
-                                 std::shared_ptr<SRTNet::NetworkConnection>& ctx) {
+                                 std::shared_ptr<SRTNet::NetworkConnection>& ctx,
+                                 const SRTNet::ConnectionInformation&) {
         {
             std::lock_guard<std::mutex> lock(connectedMutex);
             connected = true;
@@ -239,7 +241,8 @@ TEST(TestSrt, TestPsk) {
 
     auto ctx = std::make_shared<SRTNet::NetworkConnection>();
     server.clientConnected = [&](struct sockaddr& sin, SRTSOCKET newSocket,
-                                 std::shared_ptr<SRTNet::NetworkConnection>& ctx) { return ctx; };
+                                 std::shared_ptr<SRTNet::NetworkConnection>& ctx,
+                                 const SRTNet::ConnectionInformation&) { return ctx; };
     ASSERT_TRUE(server.startServer("127.0.0.1", 8009, 16, 1000, 100, SRT_LIVE_MAX_PLSIZE, 5000, kValidPsk, false, ctx));
     EXPECT_FALSE(client.startClient("127.0.0.1", 8009, 16, 1000, 100, ctx, SRT_LIVE_MAX_PLSIZE, false, 5000, kInvalidPsk))
         << "Expect to fail when using incorrect PSK";