scrcpy/app/src/server.c

#include "server.h"

#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <stdio.h>
#include <SDL2/SDL_timer.h>
#include <SDL2/SDL_platform.h>

#include "adb.h"
#include "util/file.h"
#include "util/log.h"
#include "util/net_intr.h"
#include "util/process_intr.h"
#include "util/str.h"

#define SC_SERVER_FILENAME "scrcpy-server"

#define SC_SERVER_PATH_DEFAULT PREFIX "/share/scrcpy/" SC_SERVER_FILENAME
#define SC_DEVICE_SERVER_PATH "/data/local/tmp/scrcpy-server.jar"

static char *
get_server_path(void) {
#ifdef __WINDOWS__
    const wchar_t *server_path_env = _wgetenv(L"SCRCPY_SERVER_PATH");
#else
    const char *server_path_env = getenv("SCRCPY_SERVER_PATH");
#endif
    if (server_path_env) {
        // if the envvar is set, use it
#ifdef __WINDOWS__
        char *server_path = sc_str_from_wchars(server_path_env);
#else
        char *server_path = strdup(server_path_env);
#endif
        if (!server_path) {
            LOGE("Could not allocate memory");
            return NULL;
        }
        LOGD("Using SCRCPY_SERVER_PATH: %s", server_path);
        return server_path;
    }

#ifndef PORTABLE
    LOGD("Using server: " SC_SERVER_PATH_DEFAULT);
    char *server_path = strdup(SC_SERVER_PATH_DEFAULT);
    if (!server_path) {
        LOGE("Could not allocate memory");
        return NULL;
    }
#else
    char *server_path = sc_file_get_local_path(SC_SERVER_FILENAME);
    if (!server_path) {
        LOGE("Could not get local file path, "
             "using " SC_SERVER_FILENAME " from current directory");
        return strdup(SC_SERVER_FILENAME);
    }

    LOGD("Using server (portable): %s", server_path);
#endif

    return server_path;
}

static void
sc_server_params_destroy(struct sc_server_params *params) {
    // The server stores a copy of the params provided by the user
    free((char *) params->serial);
    free((char *) params->crop);
    free((char *) params->codec_options);
    free((char *) params->encoder_name);
}

static bool
sc_server_params_copy(struct sc_server_params *dst,
                      const struct sc_server_params *src) {
    *dst = *src;

    // The params reference user-allocated memory, so we must copy them to
    // handle them from another thread

#define COPY(FIELD) \
    dst->FIELD = NULL; \
    if (src->FIELD) { \
        dst->FIELD = strdup(src->FIELD); \
        if (!dst->FIELD) { \
            goto error; \
        } \
    }

    COPY(serial);
    COPY(crop);
    COPY(codec_options);
    COPY(encoder_name);
#undef COPY

    return true;

error:
    sc_server_params_destroy(dst);
    return false;
}

static bool
push_server(struct sc_intr *intr, const char *serial) {
    char *server_path = get_server_path();
    if (!server_path) {
        return false;
    }
    if (!sc_file_is_regular(server_path)) {
        LOGE("'%s' does not exist or is not a regular file\n", server_path);
        free(server_path);
        return false;
    }
    sc_pid pid = adb_push(serial, server_path, SC_DEVICE_SERVER_PATH);
    free(server_path);
    return sc_process_check_success_intr(intr, pid, "adb push");
}

static const char *
log_level_to_server_string(enum sc_log_level level) {
    switch (level) {
        case SC_LOG_LEVEL_VERBOSE:
            return "verbose";
        case SC_LOG_LEVEL_DEBUG:
            return "debug";
        case SC_LOG_LEVEL_INFO:
            return "info";
        case SC_LOG_LEVEL_WARN:
            return "warn";
        case SC_LOG_LEVEL_ERROR:
            return "error";
        default:
            assert(!"unexpected log level");
            return "(unknown)";
    }
}

static sc_pid
execute_server(struct sc_server *server,
               const struct sc_server_params *params) {
    const char *serial = server->params.serial;

    char max_size_string[6];
    char bit_rate_string[11];
    char max_fps_string[6];
    char lock_video_orientation_string[5];
    char display_id_string[11];
    sprintf(max_size_string, "%"PRIu16, params->max_size);
    sprintf(bit_rate_string, "%"PRIu32, params->bit_rate);
    sprintf(max_fps_string, "%"PRIu16, params->max_fps);
    sprintf(lock_video_orientation_string, "%"PRIi8,
            params->lock_video_orientation);
    sprintf(display_id_string, "%"PRIu32, params->display_id);
    const char *const cmd[] = {
        "shell",
        "CLASSPATH=" SC_DEVICE_SERVER_PATH,
        "app_process",
#ifdef SERVER_DEBUGGER
# define SERVER_DEBUGGER_PORT "5005"
# ifdef SERVER_DEBUGGER_METHOD_NEW
        /* Android 9 and above */
        "-XjdwpProvider:internal -XjdwpOptions:transport=dt_socket,suspend=y,"
        "server=y,address="
# else
        /* Android 8 and below */
        "-agentlib:jdwp=transport=dt_socket,suspend=y,server=y,address="
# endif
            SERVER_DEBUGGER_PORT,
#endif
        "/", // unused
        "com.genymobile.scrcpy.Server",
        SCRCPY_VERSION,
        log_level_to_server_string(params->log_level),
        max_size_string,
        bit_rate_string,
        max_fps_string,
        lock_video_orientation_string,
        server->tunnel.forward ? "true" : "false",
        params->crop ? params->crop : "-",
        "true", // always send frame meta (packet boundaries + timestamp)
        params->control ? "true" : "false",
        display_id_string,
        params->show_touches ? "true" : "false",
        params->stay_awake ? "true" : "false",
        params->codec_options ? params->codec_options : "-",
        params->encoder_name ? params->encoder_name : "-",
        params->power_off_on_close ? "true" : "false",
    };
#ifdef SERVER_DEBUGGER
    LOGI("Server debugger waiting for a client on device port "
         SERVER_DEBUGGER_PORT "...");
    // From the computer, run
    //     adb forward tcp:5005 tcp:5005
    // Then, from Android Studio: Run > Debug > Edit configurations...
    // On the left, click on '+', "Remote", with:
    //     Host: localhost
    //     Port: 5005
    // Then click on "Debug"
#endif
    return adb_execute(serial, cmd, ARRAY_LEN(cmd));
}

static bool
connect_and_read_byte(struct sc_intr *intr, sc_socket socket, uint16_t port) {
    bool ok = net_connect_intr(intr, socket, IPV4_LOCALHOST, port);
    if (!ok) {
        return false;
    }

    char byte;
    // the connection may succeed even if the server behind the "adb tunnel"
    // is not listening, so read one byte to detect a working connection
    if (net_recv(socket, &byte, 1) != 1) {
        // the server is not listening yet behind the adb tunnel
        return false;
    }

    return true;
}

static sc_socket
connect_to_server(struct sc_server *server, uint32_t attempts, sc_tick delay) {
    uint16_t port = server->tunnel.local_port;
    do {
        LOGD("Remaining connection attempts: %d", (int) attempts);
        sc_socket socket = net_socket();
        if (socket != SC_SOCKET_NONE) {
            bool ok = connect_and_read_byte(&server->intr, socket, port);
            if (ok) {
                // it worked!
                return socket;
            }

            net_close(socket);
        }
        if (attempts) {
            sc_mutex_lock(&server->mutex);
            sc_tick deadline = sc_tick_now() + delay;
            bool timed_out = false;
            while (!server->stopped && !timed_out) {
                timed_out = !sc_cond_timedwait(&server->cond_stopped,
                                               &server->mutex, deadline);
            }
            bool stopped = server->stopped;
            sc_mutex_unlock(&server->mutex);

            if (stopped) {
                LOGI("Connection attempt stopped");
                break;
            }
        }
    } while (--attempts > 0);
    return SC_SOCKET_NONE;
}

bool
sc_server_init(struct sc_server *server, const struct sc_server_params *params,
              const struct sc_server_callbacks *cbs, void *cbs_userdata) {
    bool ok = sc_server_params_copy(&server->params, params);
    if (!ok) {
        LOGE("Could not copy server params");
        return false;
    }

    ok = sc_mutex_init(&server->mutex);
    if (!ok) {
        LOGE("Could not create server mutex");
        sc_server_params_destroy(&server->params);
        return false;
    }

    ok = sc_cond_init(&server->cond_stopped);
    if (!ok) {
        LOGE("Could not create server cond_stopped");
        sc_mutex_destroy(&server->mutex);
        sc_server_params_destroy(&server->params);
        return false;
    }

    ok = sc_intr_init(&server->intr);
    if (!ok) {
        LOGE("Could not create intr");
        sc_cond_destroy(&server->cond_stopped);
        sc_mutex_destroy(&server->mutex);
        sc_server_params_destroy(&server->params);
        return false;
    }

    server->stopped = false;

    server->video_socket = SC_SOCKET_NONE;
    server->control_socket = SC_SOCKET_NONE;

    sc_adb_tunnel_init(&server->tunnel);

    assert(cbs);
    assert(cbs->on_connection_failed);
    assert(cbs->on_connected);
    assert(cbs->on_disconnected);

    server->cbs = cbs;
    server->cbs_userdata = cbs_userdata;

    return true;
}

static bool
device_read_info(sc_socket device_socket, struct sc_server_info *info) {
    unsigned char buf[SC_DEVICE_NAME_FIELD_LENGTH + 4];
    ssize_t r = net_recv_all(device_socket, buf, sizeof(buf));
    if (r < SC_DEVICE_NAME_FIELD_LENGTH + 4) {
        LOGE("Could not retrieve device information");
        return false;
    }
    // in case the client sends garbage
    buf[SC_DEVICE_NAME_FIELD_LENGTH - 1] = '\0';
    memcpy(info->device_name, (char *) buf, sizeof(info->device_name));

    info->frame_size.width = (buf[SC_DEVICE_NAME_FIELD_LENGTH] << 8)
                           | buf[SC_DEVICE_NAME_FIELD_LENGTH + 1];
    info->frame_size.height = (buf[SC_DEVICE_NAME_FIELD_LENGTH + 2] << 8)
                            | buf[SC_DEVICE_NAME_FIELD_LENGTH + 3];
    return true;
}

static bool
sc_server_connect_to(struct sc_server *server, struct sc_server_info *info) {
    struct sc_adb_tunnel *tunnel = &server->tunnel;

    assert(tunnel->enabled);

    const char *serial = server->params.serial;

    sc_socket video_socket = SC_SOCKET_NONE;
    sc_socket control_socket = SC_SOCKET_NONE;
    if (!tunnel->forward) {
        video_socket = net_accept(tunnel->server_socket);
        if (video_socket == SC_SOCKET_NONE) {
            goto fail;
        }

        control_socket = net_accept(tunnel->server_socket);
        if (control_socket == SC_SOCKET_NONE) {
            goto fail;
        }
    } else {
        uint32_t attempts = 100;
        sc_tick delay = SC_TICK_FROM_MS(100);
        video_socket = connect_to_server(server, attempts, delay);
        if (video_socket == SC_SOCKET_NONE) {
            goto fail;
        }

        // 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(control_socket, IPV4_LOCALHOST,
                              tunnel->local_port);
        if (!ok) {
            goto fail;
        }
    }

    // we don't need the adb tunnel anymore
    sc_adb_tunnel_close(tunnel, &server->intr, serial);

    // The sockets will be closed on stop if device_read_info() fails
    bool ok = device_read_info(video_socket, info);
    if (!ok) {
        goto fail;
    }

    assert(video_socket != SC_SOCKET_NONE);
    assert(control_socket != SC_SOCKET_NONE);

    server->video_socket = video_socket;
    server->control_socket = control_socket;

    return true;

fail:
    if (video_socket != SC_SOCKET_NONE) {
        if (!net_close(video_socket)) {
            LOGW("Could not close video socket");
        }
    }

    if (control_socket != SC_SOCKET_NONE) {
        if (!net_close(control_socket)) {
            LOGW("Could not close control socket");
        }
    }

    // Always leave this function with tunnel disabled
    sc_adb_tunnel_close(tunnel, &server->intr, serial);

    return false;
}

static void
sc_server_on_terminated(void *userdata) {
    struct sc_server *server = userdata;

    // If the server process dies before connecting to the server socket,
    // then the client will be stuck forever on accept(). To avoid the problem,
    // wake up the accept() call (or any other) when the server dies, like on
    // stop() (it is safe to call interrupt() twice).
    sc_intr_interrupt(&server->intr);

    server->cbs->on_disconnected(server, server->cbs_userdata);

    LOGD("Server terminated");
}

static int
run_server(void *data) {
    struct sc_server *server = data;

    const struct sc_server_params *params = &server->params;

    bool ok = push_server(&server->intr, params->serial);
    if (!ok) {
        goto error_connection_failed;
    }

    ok = sc_adb_tunnel_open(&server->tunnel, &server->intr, params->serial,
                            params->port_range, params->force_adb_forward);
    if (!ok) {
        goto error_connection_failed;
    }

    // server will connect to our server socket
    sc_pid pid = execute_server(server, params);
    if (pid == SC_PROCESS_NONE) {
        sc_adb_tunnel_close(&server->tunnel, &server->intr, params->serial);
        goto error_connection_failed;
    }

    static const struct sc_process_listener listener = {
        .on_terminated = sc_server_on_terminated,
    };
    struct sc_process_observer observer;
    ok = sc_process_observer_init(&observer, pid, &listener, server);
    if (!ok) {
        sc_process_terminate(pid);
        sc_process_wait(pid, true); // ignore exit code
        sc_adb_tunnel_close(&server->tunnel, &server->intr, params->serial);
        goto error_connection_failed;
    }

    ok = sc_server_connect_to(server, &server->info);
    // The tunnel is always closed by server_connect_to()
    if (!ok) {
        sc_process_terminate(pid);
        sc_process_wait(pid, true); // ignore exit code
        sc_process_observer_join(&observer);
        sc_process_observer_destroy(&observer);
        goto error_connection_failed;
    }

    // Now connected
    server->cbs->on_connected(server, server->cbs_userdata);

    // Wait for server_stop()
    sc_mutex_lock(&server->mutex);
    while (!server->stopped) {
        sc_cond_wait(&server->cond_stopped, &server->mutex);
    }
    sc_mutex_unlock(&server->mutex);

    // Give some delay for the server to terminate properly
#define WATCHDOG_DELAY SC_TICK_FROM_SEC(1)
    sc_tick deadline = sc_tick_now() + WATCHDOG_DELAY;
    bool terminated = sc_process_observer_timedwait(&observer, deadline);

    // After this delay, kill the server if it's not dead already.
    // On some devices, closing the sockets is not sufficient to wake up the
    // blocking calls while the device is asleep.
    if (!terminated) {
        // The process may have terminated since the check, but it is not
        // reaped (closed) yet, so its PID is still valid, and it is ok to call
        // sc_process_terminate() even in that case.
        LOGW("Killing the server...");
        sc_process_terminate(pid);
    }

    sc_process_observer_join(&observer);
    sc_process_observer_destroy(&observer);

    sc_process_close(pid);

    return 0;

error_connection_failed:
    server->cbs->on_connection_failed(server, server->cbs_userdata);
    return -1;
}

bool
sc_server_start(struct sc_server *server) {
    bool ok = sc_thread_create(&server->thread, run_server, "server", server);
    if (!ok) {
        LOGE("Could not create server thread");
        return false;
    }

    return true;
}

void
sc_server_stop(struct sc_server *server) {
    sc_mutex_lock(&server->mutex);
    server->stopped = true;
    sc_cond_signal(&server->cond_stopped);
    sc_intr_interrupt(&server->intr);
    sc_mutex_unlock(&server->mutex);

    sc_thread_join(&server->thread, NULL);
}

void
sc_server_destroy(struct sc_server *server) {
    sc_server_params_destroy(&server->params);
    sc_intr_destroy(&server->intr);
    sc_cond_destroy(&server->cond_stopped);
    sc_mutex_destroy(&server->mutex);
}