Add server option send_dummy_byte

If set to false, no dummy byte is written to detect a connection error.

PR #2971 <https://github.com/Genymobile/scrcpy/pull/2971>

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

@@ -46,15 +46,17 @@ public final class DesktopConnection implements Closeable {
         return localSocket;
     }
 
-    public static DesktopConnection open(boolean tunnelForward, boolean control) throws IOException {
+    public static DesktopConnection open(boolean tunnelForward, boolean control, boolean sendDummyByte) throws IOException {
         LocalSocket videoSocket;
         LocalSocket controlSocket = null;
         if (tunnelForward) {
             LocalServerSocket localServerSocket = new LocalServerSocket(SOCKET_NAME);
             try {
                 videoSocket = localServerSocket.accept();
+                if (sendDummyByte) {
                     // send one byte so the client may read() to detect a connection error
                     videoSocket.getOutputStream().write(0);
+                }
                 if (control) {
                     try {
                         controlSocket = localServerSocket.accept();

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

@@ -25,6 +25,7 @@ public class Options {
     // Options not used by the scrcpy client, but useful to use scrcpy-server directly
     private boolean sendDeviceMeta = true; // send device name and size
     private boolean sendFrameMeta = true; // send PTS so that the client may record properly
+    private boolean sendDummyByte = true; // write a byte on start to detect connection issues
 
     public Ln.Level getLogLevel() {
         return logLevel;
@@ -169,4 +170,12 @@ public class Options {
     public void setSendFrameMeta(boolean sendFrameMeta) {
         this.sendFrameMeta = sendFrameMeta;
     }
+
+    public boolean getSendDummyByte() {
+        return sendDummyByte;
+    }
+
+    public void setSendDummyByte(boolean sendDummyByte) {
+        this.sendDummyByte = sendDummyByte;
+    }
 }

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

@@ -66,8 +66,9 @@ public final class Server {
 
         boolean tunnelForward = options.isTunnelForward();
         boolean control = options.getControl();
+        boolean sendDummyByte = options.getSendDummyByte();
 
-        try (DesktopConnection connection = DesktopConnection.open(tunnelForward, control)) {
+        try (DesktopConnection connection = DesktopConnection.open(tunnelForward, control, sendDummyByte)) {
             if (options.getSendDeviceMeta()) {
                 Size videoSize = device.getScreenInfo().getVideoSize();
                 connection.sendDeviceMeta(Device.getDeviceName(), videoSize.getWidth(), videoSize.getHeight());
@@ -248,6 +249,10 @@ public final class Server {
                     boolean sendFrameMeta = Boolean.parseBoolean(value);
                     options.setSendFrameMeta(sendFrameMeta);
                     break;
+                case "send_dummy_byte":
+                    boolean sendDummyByte = Boolean.parseBoolean(value);
+                    options.setSendDummyByte(sendDummyByte);
+                    break;
                 default:
                     Ln.w("Unknown server option: " + key);
                     break;