Move server-related code to server.c

The file server.c already existed, but exposed a low-level API. Make it
higher-level, so that scrcpy.c does not handle server details directly.

app/src/command.c

@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <SDL2/SDL_log.h>
 
 #define ARRAY_LEN(a) (sizeof(a) / sizeof(a[0]))
 
@@ -63,3 +64,20 @@ process_t adb_push(const char *serial, const char *local, const char *remote) {
     const char *const adb_cmd[] = {"push", (char *) local, (char *) remote};
     return adb_execute(serial, adb_cmd, ARRAY_LEN(adb_cmd));
 }
+
+SDL_bool process_check_success(process_t proc, const char *name) {
+    if (proc == PROCESS_NONE) {
+        SDL_LogError(SDL_LOG_CATEGORY_SYSTEM, "Could not execute \"%s\"", name);
+        return SDL_FALSE;
+    }
+    exit_code_t exit_code;
+    if (!cmd_simple_wait(proc, &exit_code)) {
+        if (exit_code != NO_EXIT_CODE) {
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "\"%s\" returned with value %" PRIexitcode, name, exit_code);
+        } else {
+            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "\"%s\" exited unexpectedly", name);
+        }
+        return SDL_FALSE;
+    }
+    return SDL_TRUE;
+}

app/src/command.h

@@ -42,4 +42,8 @@ process_t adb_reverse(const char *serial, const char *device_socket_name, uint16
 process_t adb_reverse_remove(const char *serial, const char *device_socket_name);
 process_t adb_push(const char *serial, const char *local, const char *remote);
 
+// convenience function to wait for a successful process execution
+// automatically log process errors with the provided process name
+SDL_bool process_check_success(process_t process, const char *name);
+
 #endif

app/src/netutil.c

@@ -4,7 +4,7 @@
 
 // contrary to SDLNet_TCP_Send and SDLNet_TCP_Recv, SDLNet_TCP_Accept is non-blocking
 // so we need to block before calling it
-TCPsocket blocking_accept(TCPsocket server_socket) {
+TCPsocket server_socket_accept(TCPsocket server_socket) {
     SDLNet_SocketSet set = SDLNet_AllocSocketSet(1);
     if (!set) {
         SDL_LogCritical(SDL_LOG_CATEGORY_SYSTEM, "Could not allocate socket set");
@@ -19,7 +19,7 @@ TCPsocket blocking_accept(TCPsocket server_socket) {
 
     // timeout is (2^32-1) milliseconds, this should be sufficient
     if (SDLNet_CheckSockets(set, -1) != 1) {
-        SDL_LogError(SDL_LOG_CATEGORY_SYSTEM, "Could not check socket: %s", SDL_GetError());
+        SDL_LogError(SDL_LOG_CATEGORY_SYSTEM, "Could not check socket");
         SDLNet_FreeSocketSet(set);
         return NULL;
     }

app/src/netutil.h

@@ -3,6 +3,7 @@
 
 #include <SDL2/SDL_net.h>
 
-TCPsocket blocking_accept(TCPsocket server_socket);
+// blocking accept on the server socket
+TCPsocket server_socket_accept(TCPsocket server_socket);
 
 #endif

app/src/scrcpy.c

@@ -23,6 +23,7 @@
 
 #define DEVICE_NAME_FIELD_LENGTH 64
 
+static struct server server = SERVER_INITIALIZER;
 static struct screen screen = SCREEN_INITIALIZER;
 static struct frames frames;
 static struct decoder decoder;
@@ -46,14 +47,6 @@ static void count_frame(void) {
     }
 }
 
-static TCPsocket listen_on_port(Uint16 port) {
-    IPaddress addr = {
-        .host = INADDR_ANY,
-        .port = SDL_SwapBE16(port),
-    };
-    return SDLNet_TCP_Open(&addr);
-}
-
 // name must be at least DEVICE_NAME_FIELD_LENGTH bytes
 static SDL_bool read_initial_device_info(TCPsocket socket, char *device_name, struct size *size) {
     unsigned char buf[DEVICE_NAME_FIELD_LENGTH + 4];
@@ -80,23 +73,6 @@ static struct point get_mouse_point(void) {
     };
 }
 
-static int wait_for_success(process_t proc, const char *name) {
-    if (proc == PROCESS_NONE) {
-        SDL_LogError(SDL_LOG_CATEGORY_SYSTEM, "Could not execute \"%s\"", name);
-        return -1;
-    }
-    exit_code_t exit_code;
-    if (!cmd_simple_wait(proc, &exit_code)) {
-        if (exit_code != NO_EXIT_CODE) {
-            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "\"%s\" returned with value %" PRIexitcode, name, exit_code);
-        } else {
-            SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "\"%s\" exited unexpectedly", name);
-        }
-        return -1;
-    }
-    return 0;
-}
-
 static void send_keycode(enum android_keycode keycode, const char *name) {
     // send DOWN event
     struct control_event control_event = {
@@ -344,43 +320,17 @@ static void event_loop(void) {
 }
 
 SDL_bool scrcpy(const char *serial, Uint16 local_port, Uint16 max_size, Uint32 bit_rate) {
-    SDL_bool ret = SDL_TRUE;
-
-    process_t push_proc = push_server(serial);
-    if (wait_for_success(push_proc, "adb push")) {
-        return SDL_FALSE;
-    }
-
-    process_t reverse_tunnel_proc = enable_tunnel(serial, local_port);
-    if (wait_for_success(reverse_tunnel_proc, "adb reverse")) {
+    if (!server_start(&server, serial, local_port, max_size, bit_rate)) {
         return SDL_FALSE;
     }
 
-    TCPsocket server_socket = listen_on_port(local_port);
-    if (!server_socket) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Could not open video socket");
-        goto finally_adb_reverse_remove;
-    }
-
-    // server will connect to our socket
-    process_t server = start_server(serial, max_size, bit_rate);
-    if (server == PROCESS_NONE) {
-        ret = SDL_FALSE;
-        SDLNet_TCP_Close(server_socket);
-        goto finally_adb_reverse_remove;
-    }
-
     // to reduce startup time, we could be tempted to init other stuff before blocking here
     // but we should not block after SDL_Init since it handles the signals (Ctrl+C) in its
     // event loop: blocking could lead to deadlock
-    TCPsocket device_socket = blocking_accept(server_socket);
-    // we don't need the server socket anymore
-    SDLNet_TCP_Close(server_socket);
+    TCPsocket device_socket = server_connect_to(&server);
     if (!device_socket) {
-        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Could not accept video socket: %s", SDL_GetError());
-        ret = SDL_FALSE;
-        stop_server(server);
-        goto finally_adb_reverse_remove;
+        server_stop(&server, serial);
+        return SDL_FALSE;
     }
 
     char device_name[DEVICE_NAME_FIELD_LENGTH];
@@ -391,19 +341,17 @@ SDL_bool scrcpy(const char *serial, Uint16 local_port, Uint16 max_size, Uint32 b
     // to init the window immediately
     if (!read_initial_device_info(device_socket, device_name, &frame_size)) {
         SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Could not retrieve initial screen size");
-        ret = SDL_FALSE;
-        SDLNet_TCP_Close(device_socket);
-        stop_server(server);
-        goto finally_adb_reverse_remove;
+        server_stop(&server, serial);
+        return SDL_FALSE;
     }
 
     if (!frames_init(&frames)) {
-        ret = SDL_FALSE;
-        SDLNet_TCP_Close(device_socket);
-        stop_server(server);
-        goto finally_adb_reverse_remove;
+        server_stop(&server, serial);
+        return SDL_FALSE;
     }
 
+    SDL_bool ret = SDL_TRUE;
+
     decoder.frames = &frames;
     decoder.video_socket = device_socket;
 
@@ -411,22 +359,17 @@ SDL_bool scrcpy(const char *serial, Uint16 local_port, Uint16 max_size, Uint32 b
     // start the decoder
     if (!decoder_start(&decoder)) {
         ret = SDL_FALSE;
-        SDLNet_TCP_Close(device_socket);
-        stop_server(server);
+        server_stop(&server, serial);
         goto finally_destroy_frames;
     }
 
     if (!controller_init(&controller, device_socket)) {
         ret = SDL_FALSE;
-        SDLNet_TCP_Close(device_socket);
-        stop_server(server);
         goto finally_stop_decoder;
     }
 
     if (!controller_start(&controller)) {
         ret = SDL_FALSE;
-        SDLNet_TCP_Close(device_socket);
-        stop_server(server);
         goto finally_destroy_controller;
     }
 
@@ -450,28 +393,11 @@ finally_stop_and_join_controller:
 finally_destroy_controller:
     controller_destroy(&controller);
 finally_stop_decoder:
-    SDLNet_TCP_Close(device_socket);
-
-    // let the server some time to print any exception trace before killing it
-    struct timespec timespec = {
-        .tv_sec = 0,
-        .tv_nsec = 100000000, // 100ms
-    };
-    nanosleep(&timespec, NULL); // ignore error
-
     // kill the server before decoder_join() to wake up the decoder
-    stop_server(server);
+    server_stop(&server, serial);
     decoder_join(&decoder);
 finally_destroy_frames:
     frames_destroy(&frames);
-finally_adb_reverse_remove:
-    {
-        process_t remove = disable_tunnel(serial);
-        if (remove != PROCESS_NONE) {
-            // ignore failure
-            cmd_simple_wait(remove, NULL);
-        }
-    }
 
     return ret;
 }

app/src/server.c

@@ -1,28 +1,34 @@
-#include "command.h"
+#include "server.h"
 
 #include <SDL2/SDL_log.h>
+#include <SDL2/SDL_net.h>
 #include <errno.h>
 #include <stdint.h>
+#include <time.h>
+#include "netutil.h"
 
 #define SOCKET_NAME "scrcpy"
 
-process_t push_server(const char *serial) {
+static SDL_bool push_server(const char *serial) {
     const char *server_path = getenv("SCRCPY_SERVER_JAR");
     if (!server_path) {
         server_path = "scrcpy-server.jar";
     }
-    return adb_push(serial, server_path, "/data/local/tmp/scrcpy-server.jar");
+    process_t process = adb_push(serial, server_path, "/data/local/tmp/scrcpy-server.jar");
+    return process_check_success(process, "adb push");
 }
 
-process_t enable_tunnel(const char *serial, Uint16 local_port) {
-    return adb_reverse(serial, SOCKET_NAME, local_port);
+static SDL_bool enable_tunnel(const char *serial, Uint16 local_port) {
+    process_t process = adb_reverse(serial, SOCKET_NAME, local_port);
+    return process_check_success(process, "adb reverse");
 }
 
-process_t disable_tunnel(const char *serial) {
-    return adb_reverse_remove(serial, SOCKET_NAME);
+static SDL_bool disable_tunnel(const char *serial) {
+    process_t process = adb_reverse_remove(serial, SOCKET_NAME);
+    return process_check_success(process, "adb reverse --remove");
 }
 
-process_t start_server(const char *serial, Uint16 max_size, Uint32 bit_rate) {
+static process_t execute_server(const char *serial, Uint16 max_size, Uint32 bit_rate) {
     char max_size_string[6];
     char bit_rate_string[11];
     sprintf(max_size_string, "%"PRIu16, max_size);
@@ -39,8 +45,89 @@ process_t start_server(const char *serial, Uint16 max_size, Uint32 bit_rate) {
     return adb_execute(serial, cmd, sizeof(cmd) / sizeof(cmd[0]));
 }
 
-void stop_server(process_t server) {
+static void terminate_server(process_t server) {
     if (!cmd_terminate(server)) {
         SDL_LogError(SDL_LOG_CATEGORY_SYSTEM, "Could not terminate server: %s", strerror(errno));
     }
 }
+
+static TCPsocket listen_on_port(Uint16 port) {
+    IPaddress addr = {
+        .host = INADDR_ANY,
+        .port = SDL_SwapBE16(port),
+    };
+    return SDLNet_TCP_Open(&addr);
+}
+
+void server_init(struct server *server) {
+    *server = (struct server) SERVER_INITIALIZER;
+}
+
+SDL_bool server_start(struct server *server, const char *serial, Uint16 local_port,
+                      Uint16 max_size, Uint32 bit_rate) {
+    if (!push_server(serial)) {
+        return SDL_FALSE;
+    }
+
+    if (!enable_tunnel(serial, local_port)) {
+        return SDL_FALSE;
+    }
+
+    // At the application level, the device part is "the server" because it
+    // serves video stream and control. However, at network level, the client
+    // listens and the server connects to the client. That way, the client can
+    // listen before starting the server app, so there is no need to try to
+    // connect until the server socket is listening on the device.
+
+    server->server_socket = listen_on_port(local_port);
+    if (!server->server_socket) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Could not listen on port %" PRIu16, local_port);
+        disable_tunnel(serial);
+        return SDL_FALSE;
+    }
+
+    // server will connect to our server socket
+    server->process = execute_server(serial, max_size, bit_rate);
+    if (server->process == PROCESS_NONE) {
+        SDLNet_TCP_Close(server->server_socket);
+        disable_tunnel(serial);
+        return SDL_FALSE;
+    }
+
+    server->adb_reverse_enabled = SDL_TRUE;
+
+    return SDL_TRUE;
+}
+
+TCPsocket server_connect_to(struct server *server) {
+    SDL_assert(server->server_socket);
+    server->device_socket = server_socket_accept(server->server_socket);
+    // we don't need the server socket anymore
+    SDLNet_TCP_Close(server->server_socket);
+    server->server_socket = NULL;
+    return server->device_socket;
+}
+
+void server_stop(struct server *server, const char *serial) {
+    SDL_assert(server->process != PROCESS_NONE);
+    if (server->server_socket) {
+        SDLNet_TCP_Close(server->server_socket);
+    }
+    if (server->device_socket) {
+        SDLNet_TCP_Close(server->device_socket);
+    }
+
+    // let the server some time to print any exception trace before killing it
+    struct timespec timespec = {
+        .tv_sec = 0,
+        .tv_nsec = 100000000, // 100ms
+    };
+    nanosleep(&timespec, NULL); // ignore error
+
+    terminate_server(server->process);
+
+    if (server->adb_reverse_enabled) {
+        // ignore failure
+        disable_tunnel(serial);
+    }
+}

app/src/server.h

@@ -1,13 +1,34 @@
 #ifndef SERVER_H
 #define SERVER_H
 
+#include <SDL2/SDL_net.h>
 #include "command.h"
 
-process_t push_server(const char *serial);
-process_t enable_tunnel(const char *serial, Uint16 local_port);
-process_t disable_tunnel(const char *serial);
+struct server {
+    process_t process;
+    TCPsocket server_socket;
+    TCPsocket device_socket;
+    SDL_bool adb_reverse_enabled;
+};
 
-process_t start_server(const char *serial, Uint16 max_size, Uint32 bit_rate);
-void stop_server(process_t server);
+#define SERVER_INITIALIZER {          \
+    .process = PROCESS_NONE,          \
+    .server_socket = NULL,            \
+    .device_socket = NULL,            \
+    .adb_reverse_enabled = SDL_FALSE, \
+}
+
+// init default values
+void server_init(struct server *server);
+
+// push, enable tunnel et start the server
+SDL_bool server_start(struct server *server, const char *serial, Uint16 local_port,
+                      Uint16 max_size, Uint32 bit_rate);
+
+// block until the communication with the server is established
+TCPsocket server_connect_to(struct server *server);
+
+// disconnect and kill the server process
+void server_stop(struct server *server, const char *serial);
 
 #endif