Send device name on the socket

Make the server send the device name along with the width and height, so
that the client may use it as the window title.

app/src/screen.c

@@ -14,6 +14,7 @@
 #include "lockutil.h"
 #include "netutil.h"
 
+#define DEVICE_NAME_FIELD_LENGTH 64
 #define SOCKET_NAME "scrcpy"
 #define DISPLAY_MARGINS 96
 #define MIN(X,Y) (X) < (Y) ? (X) : (Y)
@@ -58,13 +59,18 @@ static void stop_server(process_t server) {
     }
 }
 
-SDL_bool read_initial_device_size(TCPsocket socket, struct size *size) {
-    unsigned char buf[4];
+// name must be at least DEVICE_NAME_FIELD_LENGTH bytes
+SDL_bool read_initial_device_info(TCPsocket socket, char *device_name, struct size *size) {
+    unsigned char buf[DEVICE_NAME_FIELD_LENGTH + 4];
     if (SDLNet_TCP_Recv(socket, buf, sizeof(buf)) <= 0) {
         return SDL_FALSE;
     }
-    size->width = (buf[0] << 8) | buf[1];
-    size->height = (buf[2] << 8) | buf[3];
+    buf[DEVICE_NAME_FIELD_LENGTH - 1] = '\0'; // in case the client sends garbage
+    // scrcpy is safe here, since name contains at least DEVICE_NAME_FIELD_LENGTH bytes
+    // and strlen(buf) < DEVICE_NAME_FIELD_LENGTH
+    strcpy(device_name, (char *) buf);
+    size->width = (buf[DEVICE_NAME_FIELD_LENGTH] << 8) | buf[DEVICE_NAME_FIELD_LENGTH + 1];
+    size->height = (buf[DEVICE_NAME_FIELD_LENGTH + 2] << 8) | buf[DEVICE_NAME_FIELD_LENGTH + 3];
     return SDL_TRUE;
 }
 
@@ -252,11 +258,12 @@ int show_screen(const char *serial, Uint16 local_port) {
     }
 
     struct size frame_size;
+    char device_name[DEVICE_NAME_FIELD_LENGTH];
 
     // screenrecord does not send frames when the screen content does not change
     // therefore, we transmit the screen size before the video stream, to be able
     // to init the window immediately
-    if (!read_initial_device_size(device_socket, &frame_size)) {
+    if (!read_initial_device_info(device_socket, device_name, &frame_size)) {
         SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Could not retrieve initial screen size");
         ret = -1;
         SDLNet_TCP_Close(device_socket);
@@ -297,7 +304,7 @@ int show_screen(const char *serial, Uint16 local_port) {
     }
 
     struct size window_size = get_initial_optimal_size(frame_size);
-    SDL_Window *window = SDL_CreateWindow("scrcpy", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
+    SDL_Window *window = SDL_CreateWindow(device_name, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
                                           window_size.width, window_size.height, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
     if (!window) {
         SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "Could not create window: %s", SDL_GetError());

server/Makefile

@@ -18,10 +18,10 @@ ANDROID_JAR := $(ANDROID_HOME)/platforms/android-26/android.jar
 AIDL_SRC := android/view/IRotationWatcher.aidl
 SRC := com/genymobile/scrcpy/ScrCpyServer.java \
 	com/genymobile/scrcpy/DesktopConnection.java \
+	com/genymobile/scrcpy/DeviceUtil.java \
 	com/genymobile/scrcpy/ScreenInfo.java \
 	com/genymobile/scrcpy/ScreenStreamer.java \
 	com/genymobile/scrcpy/ScreenStreamerSession.java \
-	com/genymobile/scrcpy/ScreenUtil.java \
 
 JAR := scrcpy-server.jar
 MAIN := com.genymobile.scrcpy.ScrCpyServer

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

@@ -5,9 +5,12 @@ import android.net.LocalSocketAddress;
 
 import java.io.Closeable;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 
 public class DesktopConnection implements Closeable {
 
+    private static final int DEVICE_NAME_FIELD_LENGTH = 64;
+
     private static final String SOCKET_NAME = "scrcpy";
 
     private final LocalSocket socket;
@@ -22,9 +25,9 @@ public class DesktopConnection implements Closeable {
         return localSocket;
     }
 
-    public static DesktopConnection open(int width, int height) throws IOException {
+    public static DesktopConnection open(String deviceName, int width, int height) throws IOException {
         LocalSocket socket = connect(SOCKET_NAME);
-        send(socket, width, height);
+        send(socket, deviceName, width, height);
         return new DesktopConnection(socket);
     }
 
@@ -34,15 +37,21 @@ public class DesktopConnection implements Closeable {
         socket.close();
     }
 
-    private static void send(LocalSocket socket, int width, int height) throws IOException {
+    private static void send(LocalSocket socket, String deviceName, int width, int height) throws IOException {
         assert width < 0x10000 : "width may not be stored on 16 bits";
         assert height < 0x10000 : "height may not be stored on 16 bits";
-        byte[] buffer = new byte[4];
-        buffer[0] = (byte) (width >> 8);
-        buffer[1] = (byte) width;
-        buffer[2] = (byte) (height >> 8);
-        buffer[3] = (byte) height;
-        socket.getOutputStream().write(buffer, 0, 4);
+        byte[] buffer = new byte[DEVICE_NAME_FIELD_LENGTH + 4];
+
+        byte[] deviceNameBytes = deviceName.getBytes(StandardCharsets.UTF_8);
+        int len = Math.min(DEVICE_NAME_FIELD_LENGTH - 1, deviceNameBytes.length);
+        System.arraycopy(deviceNameBytes, 0, buffer, 0, len);
+        // byte[] are always 0-initialized in java, no need to set '\0' explicitly
+
+        buffer[DEVICE_NAME_FIELD_LENGTH] = (byte) (width >> 8);
+        buffer[DEVICE_NAME_FIELD_LENGTH + 1] = (byte) width;
+        buffer[DEVICE_NAME_FIELD_LENGTH + 2] = (byte) (height >> 8);
+        buffer[DEVICE_NAME_FIELD_LENGTH + 3] = (byte) height;
+        socket.getOutputStream().write(buffer, 0, buffer.length);
     }
 
     public void sendVideoStream(byte[] videoStreamBuffer, int len) throws IOException {

server/src/com/genymobile/scrcpy/DeviceUtil.java

@@ -1,12 +1,13 @@
 package com.genymobile.scrcpy;
 
+import android.os.Build;
 import android.os.IBinder;
 import android.os.IInterface;
 import android.view.IRotationWatcher;
 
 import java.lang.reflect.Method;
 
-public class ScreenUtil {
+public class DeviceUtil {
 
     private static final ServiceManager serviceManager = new ServiceManager();
 
@@ -18,6 +19,10 @@ public class ScreenUtil {
         serviceManager.getWindowManager().registerRotationWatcher(rotationWatcher);
     }
 
+    public static String getDeviceName() {
+        return Build.MODEL;
+    }
+
     private static class ServiceManager {
         private Method getServiceMethod;
 

server/src/com/genymobile/scrcpy/ScrCpyServer.java

@@ -5,10 +5,11 @@ import java.io.IOException;
 public class ScrCpyServer {
 
     public static void scrcpy() throws IOException {
-        ScreenInfo initialScreenInfo = ScreenUtil.getScreenInfo();
+        String deviceName = DeviceUtil.getDeviceName();
+        ScreenInfo initialScreenInfo = DeviceUtil.getScreenInfo();
         int width = initialScreenInfo.getLogicalWidth();
         int height = initialScreenInfo.getLogicalHeight();
-        try (DesktopConnection connection = DesktopConnection.open(width, height)) {
+        try (DesktopConnection connection = DesktopConnection.open(deviceName, width, height)) {
             try {
                 new ScreenStreamer(connection).streamScreen();
             } catch (IOException e) {

server/src/com/genymobile/scrcpy/ScreenStreamer.java

@@ -13,7 +13,7 @@ public class ScreenStreamer {
 
     public ScreenStreamer(DesktopConnection connection) {
         this.connection = connection;
-        ScreenUtil.registerRotationWatcher(new IRotationWatcher.Stub() {
+        DeviceUtil.registerRotationWatcher(new IRotationWatcher.Stub() {
             @Override
             public void onRotationChanged(int rotation) throws RemoteException {
                 reset();