Add LiInterruptConnection() to interrupt LiStartConnection()

src/Connection.c

@@ -17,6 +17,7 @@ CONNECTION_LISTENER_CALLBACKS ListenerCallbacks;
 DECODER_RENDERER_CALLBACKS VideoCallbacks;
 AUDIO_RENDERER_CALLBACKS AudioCallbacks;
 int NegotiatedVideoFormat;
+volatile int ConnectionInterrupted;
 
 // Connection stages
 static const char* stageNames[STAGE_MAX] = {
@@ -39,11 +40,21 @@ const char* LiGetStageName(int stage) {
     return stageNames[stage];
 }
 
+// Interrupt a pending connection attempt. This interruption happens asynchronously
+// so it is not safe to start another connection before LiStartConnection() returns.
+void LiInterruptConnection(void) {
+    // Signal anyone waiting on the global interrupted flag
+    ConnectionInterrupted = 1;
+}
+
 // Stop the connection by undoing the step at the current stage and those before it
 void LiStopConnection(void) {
     // Disable termination callbacks now
     alreadyTerminated = 1;
 
+    // Set the interrupted flag
+    LiInterruptConnection();
+
     if (stage == STAGE_INPUT_STREAM_START) {
         Limelog("Stopping input stream...");
         stopInputStream();
@@ -93,10 +104,8 @@ void LiStopConnection(void) {
         Limelog("done\n");
     }
     if (stage == STAGE_RTSP_HANDSHAKE) {
-        Limelog("Terminating RTSP handshake...");
+        // Nothing to do
-        terminateRtspHandshake();
         stage--;
-        Limelog("done\n");
     }
     if (stage == STAGE_NAME_RESOLUTION) {
         // Nothing to do
@@ -236,6 +245,7 @@ int LiStartConnection(PSERVER_INFORMATION serverInfo, PSTREAM_CONFIGURATION stre
     ListenerCallbacks.connectionTerminated = ClInternalConnectionTerminated;
 
     alreadyTerminated = 0;
+    ConnectionInterrupted = 0;
 
     Limelog("Initializing platform...");
     ListenerCallbacks.stageStarting(STAGE_PLATFORM_INIT);

src/ControlStream.c

@@ -290,9 +290,19 @@ static int sendMessageEnet(short ptype, short paylen, const void* payload) {
 
     LC_ASSERT(AppVersionQuad[0] >= 5);
 
-    // We may be trying to disconnect, so our peer could be gone.
+    // Gen 5+ servers do control protocol over ENet instead of TCP
-    // This check is safe because we're guaranteed to be holding enetMutex.
+    while ((err = serviceEnetHost(client, &event, 0)) > 0) {
-    if (peer == NULL) {
+        if (event.type == ENET_EVENT_TYPE_RECEIVE) {
+            enet_packet_destroy(event.packet);
+        }
+        else if (event.type == ENET_EVENT_TYPE_DISCONNECT) {
+            Limelog("Control stream received disconnect event\n");
+            return 0;
+        }
+    }
+    
+    if (err < 0) {
+        Limelog("Control stream connection failed\n");
         return 0;
     }
 
@@ -304,23 +314,6 @@ static int sendMessageEnet(short ptype, short paylen, const void* payload) {
     packet->type = ptype;
     memcpy(&packet[1], payload, paylen);
 
-    // Gen 5+ servers do control protocol over ENet instead of TCP
-    while ((err = serviceEnetHost(client, &event, 0)) > 0) {
-        if (event.type == ENET_EVENT_TYPE_RECEIVE) {
-            enet_packet_destroy(event.packet);
-        }
-        else if (event.type == ENET_EVENT_TYPE_DISCONNECT) {
-            Limelog("Control stream received disconnect event\n");
-            free(packet);
-            return 0;
-        }
-    }
-    
-    if (err < 0) {
-        Limelog("Control stream connection failed\n");
-        return 0;
-    }
-
     enetPacket = enet_packet_create(packet, sizeof(*packet) + paylen, ENET_PACKET_FLAG_RELIABLE);
     if (enetPacket == NULL) {
         free(packet);
@@ -571,12 +564,8 @@ int stopControlStream(void) {
     LbqSignalQueueShutdown(&invalidReferenceFrameTuples);
     PltSetEvent(&invalidateRefFramesEvent);
 
-    if (peer != NULL) {
+    // This must be set to stop in a timely manner
-        PltLockMutex(&enetMutex);
+    LC_ASSERT(ConnectionInterrupted);
-        enet_peer_disconnect_now(peer, 0);
-        peer = NULL;
-        PltUnlockMutex(&enetMutex);
-    }
 
     if (ctlSock != INVALID_SOCKET) {
         shutdownTcpSocket(ctlSock);
@@ -591,6 +580,10 @@ int stopControlStream(void) {
     PltCloseThread(&lossStatsThread);
     PltCloseThread(&invalidateRefFramesThread);
 
+    if (peer != NULL) {
+        enet_peer_reset(peer);
+        peer = NULL;
+    }
     if (client != NULL) {
         enet_host_destroy(client);
         client = NULL;
@@ -731,13 +724,8 @@ int startControlStream(void) {
         if (ctlSock != INVALID_SOCKET) {
             shutdownTcpSocket(ctlSock);
         }
-
+        else {
-        if (peer != NULL) {
+            ConnectionInterrupted = 1;
-            // We must use the mutex here because we have a live thread now.
-            PltLockMutex(&enetMutex);
-            enet_peer_disconnect_now(peer, 0);
-            peer = NULL;
-            PltUnlockMutex(&enetMutex);
         }
 
         PltInterruptThread(&lossStatsThread);
@@ -749,6 +737,8 @@ int startControlStream(void) {
             ctlSock = INVALID_SOCKET;
         }
         else {
+            enet_peer_disconnect_now(peer, 0);
+            peer = NULL;
             enet_host_destroy(client);
             client = NULL;
         }

src/Limelight-internal.h

@@ -18,6 +18,7 @@ extern CONNECTION_LISTENER_CALLBACKS ListenerCallbacks;
 extern DECODER_RENDERER_CALLBACKS VideoCallbacks;
 extern AUDIO_RENDERER_CALLBACKS AudioCallbacks;
 extern int NegotiatedVideoFormat;
+extern volatile int ConnectionInterrupted;
 
 int isBeforeSignedInt(int numA, int numB, int ambiguousCase);
 int serviceEnetHost(ENetHost* client, ENetEvent* event, enet_uint32 timeoutMs);
@@ -40,7 +41,6 @@ void connectionLostPackets(int lastReceivedPacket, int nextReceivedPacket);
 int sendInputPacketOnControlStream(unsigned char* data, int length);
 
 int performRtspHandshake(void);
-void terminateRtspHandshake(void);
 
 void initializeVideoDepacketizer(int pktSize);
 void destroyVideoDepacketizer(void);

src/Limelight.h

@@ -240,12 +240,18 @@ void LiInitializeServerInformation(PSERVER_INFORMATION serverInfo);
 // Callbacks are all optional. Pass NULL for individual callbacks within each struct or pass NULL for the entire struct
 // to use the defaults for all callbacks.
 //
+// This function is not thread-safe.
+//
 int LiStartConnection(PSERVER_INFORMATION serverInfo, PSTREAM_CONFIGURATION streamConfig, PCONNECTION_LISTENER_CALLBACKS clCallbacks,
     PDECODER_RENDERER_CALLBACKS drCallbacks, PAUDIO_RENDERER_CALLBACKS arCallbacks, void* renderContext, int drFlags);
 
-// This function stops streaming.
+// This function stops streaming. This function is not thread-safe.
 void LiStopConnection(void);
 
+// This function interrupts a pending LiStartConnection() call. This interruption happens asynchronously
+// so it is not safe to start another connection before the first LiStartConnection() call returns.
+void LiInterruptConnection(void);
+
 // Use to get a user-visible string to display initialization progress
 // from the integer passed to the ConnListenerStageXXX callbacks
 const char* LiGetStageName(int stage);

src/Misc.c

@@ -1,20 +1,31 @@
 #include "Limelight-internal.h"
 
-#define ENET_SERVICE_RETRIES 10
+#define ENET_INTERNAL_TIMEOUT_MS 100
 
 // This function wraps enet_host_service() and hides the fact that it must be called
 // multiple times for retransmissions to work correctly. It is meant to be a drop-in
-// replacement for enet_host_service().
+// replacement for enet_host_service(). It also handles cancellation of the connection
+// attempt during the wait.
 int serviceEnetHost(ENetHost* client, ENetEvent* event, enet_uint32 timeoutMs) {
-    int i;
+    int ret;
-    int ret = -1;
 
     // We need to call enet_host_service() multiple times to make sure retransmissions happen
-    for (i = 0; i < ENET_SERVICE_RETRIES; i++) {
+    for (;;) {
-        ret = enet_host_service(client, event, timeoutMs / ENET_SERVICE_RETRIES);
+        int selectedTimeout = timeoutMs < ENET_INTERNAL_TIMEOUT_MS ? timeoutMs : ENET_INTERNAL_TIMEOUT_MS;
+
+        // We want to report an interrupt event if we are able to read data
+        if (ConnectionInterrupted) {
+            Limelog("ENet wait interrupted\n");
+            ret = -1;
+            break;
+        }
+
+        ret = enet_host_service(client, event, selectedTimeout);
         if (ret != 0 || timeoutMs == 0) {
             break;
         }
+
+        timeoutMs -= selectedTimeout;
     }
     
     return ret;

src/RtspConnection.c

@@ -281,17 +281,6 @@ static int transactRtspMessage(PRTSP_MESSAGE request, PRTSP_MESSAGE response, in
     }
 }
 
-// Terminate the RTSP Handshake process by shutting down the socket.
-// The thread waiting on RTSP will close the socket.
-void terminateRtspHandshake(void) {
-    if (sock != INVALID_SOCKET) {
-        shutdownTcpSocket(sock);
-    }
-    
-    // FIXME: We should try to interrupt ENet here, but we must
-    // be sure to do it safely. We may need to add a new lock for this.
-}
-
 // Send RTSP OPTIONS request
 static int requestOptions(PRTSP_MESSAGE response, int* error) {
     RTSP_MESSAGE request;