STM32F207以太网+LAN8742传输服务器会卡死

李嘉辉

单片机作为服务器把数据传输到电脑客户端，客户端与服务器是一问一答的通讯方式，传输一段时间后服务器就会卡死，调试后发现卡死后服务器不会进入tcp_echoserver_recv函数
在网上搜了相关问题大多都说是这个接收函数的问题，自己就修改了几行数据接受和发送代码，大神看看问题出现在了那里
static err_t tcp_echoserver_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err)
{
  struct tcp_echoserver_struct *es;
  err_t ret_err;
        u16 i;

  LWIP_ASSERT("arg != NULL",arg != NULL);
  
  es = (struct tcp_echoserver_struct *)arg;
  
  /* if we receive an empty tcp frame from client => close connection */
  if (p == NULL)//空帧释放链接
  {
    /* remote host closed connection */
    es->state = ES_CLOSING;
    if(es->p == NULL)
    {
      /* we're done sending, close connection */
      tcp_echoserver_connection_close(tpcb, es);
                        transFlag = 0;
                        nextFlag = 0;
    }
    else
    {
      /* we're not done yet */
      /* acknowledge received packet */
      tcp_sent(tpcb, tcp_echoserver_sent);
      
      /* send remaining data*/
      tcp_echoserver_send(tpcb, es);
    }
    ret_err = ERR_OK;
  }   
  /* else : a non empty frame was received from client but for some reason err != ERR_OK */
  else if(err != ERR_OK)//非空，但是出错，释放缓存
  {
    /* free received pbuf*/
    if (p != NULL)
    {
      es->p = NULL;
      pbuf_free(p);
    }
    ret_err = err;
  }
  else if(es->state == ES_ACCEPTED)//连接成功，sent回调
  {
    /* first data chunk in p->payload */
    es->state = ES_RECEIVED;
   
    /* store reference to incoming pbuf (chain) */
    es->p = p;
   
    /* initialize LwIP tcp_sent callback function */
                  tcp_sent(tpcb, tcp_echoserver_sent);
                /* send back the received data (echo) */
               
                //20180322
                tcp_recved(tpcb, p->tot_len);                //yry20180322第一次连接时的数据
                memset(&serverRxBuf[serverRxCMDRecePos],0,serverRxCMDCount);
                memcpy(&serverRxBuf[serverRxCMDRecePos][0], p->payload, p->len);
                serverRxCMDRecePos++;
                serverRxCMDRecePos %= serverRxBufSize;                
               
                //20190808                       
                tcp_echoserver_pcb = tpcb;
                pbuf_free(p);
    ret_err = ERR_OK;
  }
  else if (es->state == ES_RECEIVED)//收到数据
  {
    /* more data received from client and previous data has been already sent*/
                if(es->p == NULL)
    {
      es->p = p;
  
      /* send back received data */
                       
                tcp_recved(tpcb, p->tot_len);       
                memset(&serverRxBuf[serverRxCMDRecePos],0,serverRxCMDCount);
                memcpy(&serverRxBuf[serverRxCMDRecePos][0], p->payload, p->len);
                serverRxCMDRecePos++;
                serverRxCMDRecePos %= serverRxBufSize;
                  pbuf_free(p);                       
                        //////////////////////
    }
    else//连接关闭，收到数据
    {
      struct pbuf *ptr;

      /* chain pbufs to the end of what we recv'ed previously  */
      ptr = es->p;
      pbuf_chain(ptr,p);
    }
    ret_err = ERR_OK;
  }
  
  /* data received when connection already closed */
  else
  {
    /* Acknowledge data reception */
    tcp_recved(tpcb, p->tot_len);
   
    /* free pbuf and do nothing */
    es->p = NULL;
    pbuf_free(p);
    ret_err = ERR_OK;
  }
  return ret_err;
}
上位机客户端卡死界面如下

李嘉辉

抓包出现这样的情况之后服务器就卡死不会再发送数据了