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());