addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    s = socket(AF_INET, type, 0);

• adb的Server与adbd的5555号端口连接，这种连接是谁先发起的？

从以下注释可以看到一些端倪

   /* try to connect to any number of running emulator instances     */
    /* this is only done when ADB starts up. later, each new emulator */
    /* will send a message to ADB to indicate that is is starting up  */
    for ( ; count > 0; count--, port += 2 ) {
        (void) local_connect(port);
    }

    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    s = socket(AF_INET, type, 0);
    connect(s, (struct sockaddr *) &addr, sizeof(addr))

...
    local_init(DEFAULT_ADB_LOCAL_TRANSPORT_PORT);//DEFAULT_ADB_LOCAL_TRANSPORT_PORT=5555
...
    char local_name[30];
    build_local_name(local_name, sizeof(local_name), server_port);//server_port=5038
    if(install_listener(local_name, "*smartsocket*", NULL, 0)) {
        exit(1);
    }

//port = 5555
void local_init(int port)
{
...
    if(HOST) {
        func = client_socket_thread;//在adb进程,属于soekct client
    } else {
       func = server_socket_thread;//在adbd进程，属于socket server
...
    adb_thread_create(&thr, func, (void *) (uintptr_t) port))
...
}

    // return a list of all connected devices
    if (!strncmp(service, "devices", 7)) {
        char buffer[4096];
        int use_long = !strcmp(service+7, "-l");
        if (use_long || service[7] == 0) {
            memset(buffer, 0, sizeof(buffer));
            D("Getting device list \n");
            list_transports(buffer, sizeof(buffer), use_long);
            D("Wrote device list \n");
            send_msg_with_okay(reply_fd, buffer, strlen(buffer));
            return 0;
        }
    }

  for(t = transport_list.next; t != &transport_list; t = t->next) {
        len = format_transport(t, p, end - p, long_listing);
        if (p + len >= end) {
            /* discard last line if buffer is too short */
            break;
        }

static void ss_listener_event_func(int _fd, unsigned ev, void *_l)
{
    asocket *s;
...
        s = create_local_socket(fd);
        if(s) {
            connect_to_smartsocket(s);
            return;
        }
    }