Add support for X-SS-Connect-Data in RTSP SETUP for control stream

This allows the host to provide a 32-bit integer that will be sent
in the data of the ENet connect event, similar to X-SS-Ping-Payload
for video and audio.

The host can use this data to uniquely identify a client when IP
addresses are not stable across the various separate connections,
such as when the client is behind a Carrier-Grade NAT.

src/Connection.c

@@ -31,6 +31,7 @@ uint16_t AudioPortNumber;
 uint16_t VideoPortNumber;
 SS_PING AudioPingPayload;
 SS_PING VideoPingPayload;
+uint32_t ControlConnectData;
 uint32_t SunshineFeatureFlags;
 
 // Connection stages

src/ControlStream.c

@@ -1625,7 +1625,7 @@ int startControlStream(void) {
         enet_socket_set_option (client->socket, ENET_SOCKOPT_QOS, 1);
 
         // Connect to the host
-        peer = enet_host_connect(client, &remoteAddress, CTRL_CHANNEL_COUNT, 0);
+        peer = enet_host_connect(client, &remoteAddress, CTRL_CHANNEL_COUNT, ControlConnectData);
         if (peer == NULL) {
             stopping = true;
             enet_host_destroy(client);

src/Limelight-internal.h

@@ -40,6 +40,7 @@ extern uint16_t VideoPortNumber;
 
 extern SS_PING AudioPingPayload;
 extern SS_PING VideoPingPayload;
+extern uint32_t ControlConnectData;
 
 extern uint32_t SunshineFeatureFlags;
 
@@ -76,6 +77,7 @@ extern uint32_t SunshineFeatureFlags;
 
 // Client feature flags for x-ml-general.featureFlags SDP attribute
 #define ML_FF_FEC_STATUS 0x01 // Client sends SS_FRAME_FEC_STATUS for frame losses
+#define ML_FF_SESSION_ID_V1 0x02 // Client supports X-SS-Ping-Payload and X-SS-Connect-Data
 
 #define UDP_RECV_POLL_TIMEOUT_MS 100
 

src/RtspConnection.c

@@ -1067,6 +1067,7 @@ int performRtspHandshake(PSERVER_INFORMATION serverInfo) {
     if (AppVersionQuad[0] >= 5) {
         RTSP_MESSAGE response;
         int error = -1;
+        char* connectData;
 
         if (!setupStream(&response,
                          controlStreamId,
@@ -1083,6 +1084,15 @@ int performRtspHandshake(PSERVER_INFORMATION serverInfo) {
             goto Exit;
         }
 
+        // Parse the Sunshine control connect data extension if present
+        connectData = getOptionContent(response.options, "X-SS-Connect-Data");
+        if (connectData != NULL) {
+            ControlConnectData = (uint32_t)strtoul(connectData, NULL, 0);
+        }
+        else {
+            ControlConnectData = 0;
+        }
+
         // Parse the control port out of the RTSP SETUP response
         LC_ASSERT(ControlPortNumber == 0);
         if (!parseServerPortFromTransport(&response, &ControlPortNumber)) {

src/SdpGenerator.c

@@ -268,7 +268,7 @@ static PSDP_OPTION getAttributesList(char*urlSafeAddr) {
 
     // Send client feature flags to Sunshine hosts
     if (IS_SUNSHINE()) {
-        uint32_t moonlightFeatureFlags = ML_FF_FEC_STATUS;
+        uint32_t moonlightFeatureFlags = ML_FF_FEC_STATUS | ML_FF_SESSION_ID_V1;
         snprintf(payloadStr, sizeof(payloadStr), "%u", moonlightFeatureFlags);
         err |= addAttributeString(&optionHead, "x-ml-general.featureFlags", payloadStr);
     }