Allow exceeding 4 controllers for Sunshine hosts

src/InputStream.c

@@ -961,6 +961,7 @@ static int sendControllerEventInternal(short controllerNumber, short activeGamep
     else {
         // Generation 4+ servers support passing the controller number
         holder->packet.multiController.header.size = BE32(sizeof(NV_MULTI_CONTROLLER_PACKET) - sizeof(uint32_t));
+
         // On Gen 5 servers, the header code is decremented by one
         if (AppVersionQuad[0] >= 5) {
             holder->packet.multiController.header.magic = LE32(MULTI_CONTROLLER_MAGIC_GEN5);
@@ -968,6 +969,13 @@ static int sendControllerEventInternal(short controllerNumber, short activeGamep
         else {
             holder->packet.multiController.header.magic = LE32(MULTI_CONTROLLER_MAGIC);
         }
+
+        // GFE only supports a maximum of 4 controllers
+        if (!IS_SUNSHINE()) {
+            controllerNumber %= 4;
+            activeGamepadMask &= 0xF;
+        }
+
         holder->packet.multiController.headerB = LE16(MC_HEADER_B);
         holder->packet.multiController.controllerNumber = LE16(controllerNumber);
         holder->packet.multiController.activeGamepadMask = LE16(activeGamepadMask);

src/Limelight.h

@@ -664,8 +664,10 @@ int LiSendControllerEvent(short buttonFlags, unsigned char leftTrigger, unsigned
 // This function queues a controller event to be sent to the remote server. The controllerNumber
 // parameter is a zero-based index of which controller this event corresponds to. The largest legal
 // controller number is 3 (for a total of 4 controllers, the Xinput maximum). On generation 3 servers (GFE 2.1.x),
-// these will be sent as controller 0 regardless of the controllerNumber parameter. The activeGamepadMask
+// these will be sent as controller 0 regardless of the controllerNumber parameter.
-// parameter is a bitfield with bits set for each controller present up to a maximum of 4 (0xF).
+//
+// The activeGamepadMask parameter is a bitfield with bits set for each controller present.
+// On GFE, activeGamepadMask is limited to a maximum of 4 (0xF). On Sunshine, it is limited to 16 (0xFFFF).
 int LiSendMultiControllerEvent(short controllerNumber, short activeGamepadMask,
     int buttonFlags, unsigned char leftTrigger, unsigned char rightTrigger,
     short leftStickX, short leftStickY, short rightStickX, short rightStickY);