Do not create control socket if no control

If --no-control is enabled, then it is not necessary to create a second
communication socket between the client and the server.

This also facilitates the use of the server alone (without the client)
to receive only the raw video stream.

app/src/server.c

@@ -388,6 +388,7 @@ sc_server_connect_to(struct sc_server *server, struct sc_server_info *info) {
     assert(tunnel->enabled);
 
     const char *serial = server->params.serial;
+    bool control = server->params.control;
 
     sc_socket video_socket = SC_SOCKET_NONE;
     sc_socket control_socket = SC_SOCKET_NONE;
@@ -397,10 +398,13 @@ sc_server_connect_to(struct sc_server *server, struct sc_server_info *info) {
             goto fail;
         }
 
-        control_socket = net_accept_intr(&server->intr, tunnel->server_socket);
+        if (control) {
+            control_socket =
+                net_accept_intr(&server->intr, tunnel->server_socket);
             if (control_socket == SC_SOCKET_NONE) {
                 goto fail;
             }
+        }
     } else {
         uint32_t tunnel_host = server->params.tunnel_host;
         if (!tunnel_host) {
@@ -420,17 +424,20 @@ sc_server_connect_to(struct sc_server *server, struct sc_server_info *info) {
             goto fail;
         }
 
-        // we know that the device is listening, we don't need several attempts
+        if (control) {
+            // we know that the device is listening, we don't need several
+            // attempts
             control_socket = net_socket();
             if (control_socket == SC_SOCKET_NONE) {
                 goto fail;
             }
-        bool ok = net_connect_intr(&server->intr, control_socket, tunnel_host,
-                                   tunnel_port);
+            bool ok = net_connect_intr(&server->intr, control_socket,
+                                       tunnel_host, tunnel_port);
             if (!ok) {
                 goto fail;
             }
         }
+    }
 
     // we don't need the adb tunnel anymore
     sc_adb_tunnel_close(tunnel, &server->intr, serial);
@@ -442,7 +449,7 @@ sc_server_connect_to(struct sc_server *server, struct sc_server_info *info) {
     }
 
     assert(video_socket != SC_SOCKET_NONE);
-    assert(control_socket != SC_SOCKET_NONE);
+    assert(!control || control_socket != SC_SOCKET_NONE);
 
     server->video_socket = video_socket;
     server->control_socket = control_socket;

server/src/main/java/com/genymobile/scrcpy/DesktopConnection.java

@@ -30,8 +30,13 @@ public final class DesktopConnection implements Closeable {
     private DesktopConnection(LocalSocket videoSocket, LocalSocket controlSocket) throws IOException {
         this.videoSocket = videoSocket;
         this.controlSocket = controlSocket;
+        if (controlSocket != null) {
             controlInputStream = controlSocket.getInputStream();
             controlOutputStream = controlSocket.getOutputStream();
+        } else {
+            controlInputStream = null;
+            controlOutputStream = null;
+        }
         videoFd = videoSocket.getFileDescriptor();
     }
 
@@ -41,26 +46,29 @@ public final class DesktopConnection implements Closeable {
         return localSocket;
     }
 
-    public static DesktopConnection open(Device device, boolean tunnelForward) throws IOException {
+    public static DesktopConnection open(Device device, boolean tunnelForward, boolean control) throws IOException {
         LocalSocket videoSocket;
-        LocalSocket controlSocket;
+        LocalSocket controlSocket = null;
         if (tunnelForward) {
             LocalServerSocket localServerSocket = new LocalServerSocket(SOCKET_NAME);
             try {
                 videoSocket = localServerSocket.accept();
                 // send one byte so the client may read() to detect a connection error
                 videoSocket.getOutputStream().write(0);
+                if (control) {
                     try {
                         controlSocket = localServerSocket.accept();
                     } catch (IOException | RuntimeException e) {
                         videoSocket.close();
                         throw e;
                     }
+                }
             } finally {
                 localServerSocket.close();
             }
         } else {
             videoSocket = connect(SOCKET_NAME);
+            if (control) {
                 try {
                     controlSocket = connect(SOCKET_NAME);
                 } catch (IOException | RuntimeException e) {
@@ -68,6 +76,7 @@ public final class DesktopConnection implements Closeable {
                     throw e;
                 }
             }
+        }
 
         DesktopConnection connection = new DesktopConnection(videoSocket, controlSocket);
         Size videoSize = device.getScreenInfo().getVideoSize();
@@ -79,10 +88,12 @@ public final class DesktopConnection implements Closeable {
         videoSocket.shutdownInput();
         videoSocket.shutdownOutput();
         videoSocket.close();
+        if (controlSocket != null) {
             controlSocket.shutdownInput();
             controlSocket.shutdownOutput();
             controlSocket.close();
         }
+    }
 
     private void send(String deviceName, int width, int height) throws IOException {
         byte[] buffer = new byte[DEVICE_NAME_FIELD_LENGTH + 4];

server/src/main/java/com/genymobile/scrcpy/Server.java

@@ -66,14 +66,15 @@ public final class Server {
         Thread initThread = startInitThread(options);
 
         boolean tunnelForward = options.isTunnelForward();
+        boolean control = options.getControl();
 
-        try (DesktopConnection connection = DesktopConnection.open(device, tunnelForward)) {
+        try (DesktopConnection connection = DesktopConnection.open(device, tunnelForward, control)) {
             ScreenEncoder screenEncoder = new ScreenEncoder(options.getSendFrameMeta(), options.getBitRate(), options.getMaxFps(), codecOptions,
                     options.getEncoderName());
 
             Thread controllerThread = null;
             Thread deviceMessageSenderThread = null;
-            if (options.getControl()) {
+            if (control) {
                 final Controller controller = new Controller(device, connection, options.getClipboardAutosync());
 
                 // asynchronous