Add basic QoS attributes to our A/V sockets

src/AudioStream.c

@@ -93,7 +93,7 @@ int notifyAudioPortNegotiationComplete(void) {
 
     // For GFE 3.22 compatibility, we must start the audio ping thread before the RTSP handshake.
     // It will not reply to our RTSP PLAY request until the audio ping has been received.
-    rtpSocket = bindUdpSocket(RemoteAddr.ss_family, &LocalAddr, AddrLen, 0);
+    rtpSocket = bindUdpSocket(RemoteAddr.ss_family, &LocalAddr, AddrLen, 0, SOCK_QOS_TYPE_AUDIO);
     if (rtpSocket == INVALID_SOCKET) {
         return LastSocketFail();
     }

src/PlatformSockets.c

@@ -235,7 +235,56 @@ void closeSocket(SOCKET s) {
 #endif
 }
 
-SOCKET bindUdpSocket(int addressFamily, struct sockaddr_storage* localAddr, SOCKADDR_LEN addrLen, int bufferSize) {
+// These set "safe" host or link-local QoS options that we can unconditionally
+// set without having to worry about routers blockholing the traffic.
+static void setSocketQos(SOCKET s, int socketQosType) {
+#ifdef SO_NET_SERVICE_TYPE
+    int value;
+    switch (socketQosType) {
+    case SOCK_QOS_TYPE_BEST_EFFORT:
+        value = NET_SERVICE_TYPE_BE;
+        break;
+    case SOCK_QOS_TYPE_AUDIO:
+        value = NET_SERVICE_TYPE_VO;
+        break;
+    case SOCK_QOS_TYPE_VIDEO:
+        value = NET_SERVICE_TYPE_VI;
+        break;
+    default:
+        Limelog("Unknown QoS type: %d\n", socketQosType);
+        return;
+    }
+
+    // iOS/macOS
+    if (setsockopt(s, SOL_SOCKET, SO_NET_SERVICE_TYPE, (char*)&value, sizeof(value)) < 0) {
+        Limelog("setsockopt(SO_NET_SERVICE_TYPE, %d) failed: %d\n", value, (int)LastSocketError());
+    }
+#endif
+#ifdef SO_PRIORITY
+    int value;
+    switch (socketQosType) {
+    case SOCK_QOS_TYPE_BEST_EFFORT:
+        value = 0;
+        break;
+    case SOCK_QOS_TYPE_AUDIO:
+        value = 6;
+        break;
+    case SOCK_QOS_TYPE_VIDEO:
+        value = 5;
+        break;
+    default:
+        Limelog("Unknown QoS type: %d\n", socketQosType);
+        return;
+    }
+
+    // Linux
+    if (setsockopt(s, SOL_SOCKET, SO_PRIORITY, (char*)&value, sizeof(value)) < 0) {
+        Limelog("setsockopt(SO_PRIORITY, %d) failed: %d\n", value, (int)LastSocketError());
+    }
+#endif
+}
+
+SOCKET bindUdpSocket(int addressFamily, struct sockaddr_storage* localAddr, SOCKADDR_LEN addrLen, int bufferSize, int socketQosType) {
     SOCKET s;
     LC_SOCKADDR bindAddr;
     int err;
@@ -294,6 +343,11 @@ SOCKET bindUdpSocket(int addressFamily, struct sockaddr_storage* localAddr, SOCK
     }
 #endif
 
+    // Enable QOS for the socket (best effort)
+    if (socketQosType != SOCK_QOS_TYPE_BEST_EFFORT) {
+        setSocketQos(s, socketQosType);
+    }
+
     if (bufferSize != 0) {
         // We start at the requested recv buffer value and step down until we find
         // a value that the OS will accept.

src/PlatformSockets.h

@@ -95,10 +95,14 @@ typedef struct sockaddr_in LC_SOCKADDR;
 #endif
 void addrToUrlSafeString(struct sockaddr_storage* addr, char* string, size_t stringLength);
 
+#define SOCK_QOS_TYPE_BEST_EFFORT 0
+#define SOCK_QOS_TYPE_AUDIO 1
+#define SOCK_QOS_TYPE_VIDEO 2
+
 SOCKET createSocket(int addressFamily, int socketType, int protocol, bool nonBlocking);
 SOCKET connectTcpSocket(struct sockaddr_storage* dstaddr, SOCKADDR_LEN addrlen, unsigned short port, int timeoutSec);
 int sendMtuSafe(SOCKET s, char* buffer, int size);
-SOCKET bindUdpSocket(int addressFamily, struct sockaddr_storage* localAddr, SOCKADDR_LEN addrLen, int bufferSize);
+SOCKET bindUdpSocket(int addressFamily, struct sockaddr_storage* localAddr, SOCKADDR_LEN addrLen, int bufferSize, int socketQosType);
 int enableNoDelay(SOCKET s);
 int setSocketNonBlocking(SOCKET s, bool enabled);
 int recvUdpSocket(SOCKET s, char* buffer, int size, bool useSelect);

src/SimpleStun.c

@@ -73,7 +73,7 @@ int LiFindExternalAddressIP4(const char* stunServer, unsigned short stunPort, un
         goto Exit;
     }
 
-    sock = bindUdpSocket(hints.ai_family, NULL, 0, 0);
+    sock = bindUdpSocket(hints.ai_family, NULL, 0, 0, SOCK_QOS_TYPE_BEST_EFFORT);
     if (sock == INVALID_SOCKET) {
         err = LastSocketFail();
         Limelog("Failed to connect to STUN server: %d\n", err);

src/VideoStream.c

@@ -337,7 +337,8 @@ int startVideoStream(void* rendererContext, int drFlags) {
     }
 
     rtpSocket = bindUdpSocket(RemoteAddr.ss_family, &LocalAddr, AddrLen,
-                              RTP_RECV_PACKETS_BUFFERED * (StreamConfig.packetSize + MAX_RTP_HEADER_SIZE));
+                              RTP_RECV_PACKETS_BUFFERED * (StreamConfig.packetSize + MAX_RTP_HEADER_SIZE),
+                              SOCK_QOS_TYPE_VIDEO);
     if (rtpSocket == INVALID_SOCKET) {
         VideoCallbacks.cleanup();
         return LastSocketError();