关于 static int ec20_socket_connect()函数的使用问题：

发布于 2018-10-31 19:20:59 浏览：2873 订阅该版

static int Sim7100_socket_connect(int socket, char *ip, int32_t port, enum at_socket_type type, rt_bool_t is_client)
{
    int result = 0, event_result = 0;
    rt_bool_t retryed = RT_FALSE;

RT_ASSERT(ip);
    RT_ASSERT(port >= 0);

/* lock AT socket connect */
    rt_mutex_take(at_event_lock, RT_WAITING_FOREVER);

__retry:

if (is_client)
 {
 switch (type)
 {
 case AT_SOCKET_TCP:
 /* send AT commands(AT+QIOPEN=<contextID>,<socket>,"<TCP/UDP>","<IP_address>/<domain_name>",<remote_port>,<local_port>,<access_mode>) to connect TCP server */
 /* contextID = 1 : use same contextID as AT+QICSGP & AT+QIACT */
 /* local_port=0 : local port assigned automatically */
 /* access_mode = 1 : Direct push mode */
 if (at_exec_cmd(RT_NULL, "AT+CIPOPEN=%d,\"TCP\",\"%s\",%d ", socket, ip, port) < 0)
 {
 result = -RT_ERROR;
 goto __exit;
 }
 break;

case AT_SOCKET_UDP:
 if (at_exec_cmd(RT_NULL, "AT+CIPOPEN=%d,\"UDP\",\"%s\",%d ", socket, ip, port) < 0)
 {
 result = -RT_ERROR;
 goto __exit;
 }
 break;

default:
            rt_kprintf("Not supported connect type : %d.", type);
            return -RT_ERROR;
        }
    }

/* waiting result event from AT URC, the device default connection timeout is 75 seconds, but it set to 10 seconds is convenient to use.*/
 if (at_socket_event_recv(SET_EVENT(socket, 0), rt_tick_from_millisecond(30 * 1000), RT_EVENT_FLAG_OR) < 0)
 {
 rt_kprintf(" socket (%d) connect failed, wait connect result timeout. ", socket);
 result = -RT_ETIMEOUT;
 goto __exit;
 }
 /* waiting OK or failed result */
 if ((event_result = at_socket_event_recv(Sim7100_EVENT_CONN_OK | Sim7100_EVENT_CONN_FAIL, rt_tick_from_millisecond(1 * 1000),
 RT_EVENT_FLAG_OR)) < 0)
 {
 rt_kprintf(" socket (%d) connect failed, wait connect OK|FAIL timeout. ", socket);
 result = -RT_ETIMEOUT;
 goto __exit;
 }
 /* check result */
 if (event_result & Sim7100_EVENT_CONN_FAIL)
 {
 if (!retryed)
 {
 rt_kprintf("socket (%d) connect failed, maybe the socket was not be closed at the last time and now will retry.", socket);
 if (Sim7100_socket_close(socket) < 0)
 {
 goto __exit;
 }
 retryed = RT_TRUE;
 goto __retry;
 }
 rt_kprintf("socket (%d) connect failed, failed to establish a connection.", socket);
 result = -RT_ERROR;
 goto __exit;
 }

__exit:
    /* unlock AT socket connect */
    rt_mutex_release(at_event_lock);

return result;
}

是这个连接函数，我用了他之后，返回正确.ok,  +CIPOPEN: 0,0..,
一般情况发送AT指令后返回这个就行了，我们这个函数后面有几个判断：于是他就再回复：socket (%d) connect failed, wait connect result timeout，
是因为什么？