应用程序不从sl_RecvFrom返回

Question

我正在使用UDP来从ntp服务器获取当前时间。

在我期待服务器响应之前，一切似乎都没问题。所以我有两种方法，第一种方法将请求发送到ntp服务器，第二种方法接收响应。我对第一个问题没有问题，但在第二个问题上，我正在努力使用sl_RecvFRom函数，因为应用程序永远不会从它返回。

我将在这里添加这两个函数的代码。

 static returnTypes_t bsdUdpServer( uint16_t AddrSize){

      int16_t Status = (int16_t) ZERO;

      SockID = sl_Socket(SL_AF_INET,SL_SOCK_DGRAM, (uint32_t) ZERO);
      if (SockID < 0){
          printf("error on sl_Socket\n\r");
          return SOCKET_ERROR;
      }

      Status = sl_Bind(SockID, (SlSockAddr_t *) &LocalAddr, AddrSize);
      if (Status < 0){
          printf("problem on sl_Bind\n\r");
          return SOCKET_ERROR;
      }

      Status = sl_RecvFrom(SockID, packetBuffer, NTP_PACKET_SIZE * sizeof(uint8_t), (uint32_t) ZERO, (SlSockAddr_t *) &Addr, &AddrSize);
      if (Status < (int16_t) ZERO){
           printf("error - no bytes received: %d\n\r", (int16_t)Status);
           return SOCKET_ERROR;
      }

      Status = sl_Close(SockID);
      if (Status < 0)
           printf("problem on sl_Close\n\r");

      uint16_t highWord = index3 << 16 | index2;
      uint16_t lowWord = index1 << 16 | index0;

      uint32_t secondsSince1900 = highWord << 16 | lowWord;

      printf("Seconds since 1 Janeiro de 1900: %ld\n\r", secondsSince1900);

      return (STATUS_OK);

 }

 static returnTypes_t bsdUdpClient(uint16_t AddrSize) {

     int16_t Status = (int16_t) ZERO;

     memset(packetBuffer, 0, NTP_PACKET_SIZE);

     packetBuffer[0] = 0xE3; //0b11100011;   // LI, Version, Mode
     packetBuffer[1] = 0x00;     // Stratum, or type of clock
     packetBuffer[2] = 0x06;     // Polling Interval
     packetBuffer[3] = 0xEC;  // Peer Clock Precision
     // 8 bytes of zero for Root Delay & Root Dispersion
     packetBuffer[12]  = 49;
     packetBuffer[13]  = 0x4E;
     packetBuffer[14]  = 49;
     packetBuffer[15]  = 52;

     SockID = sl_Socket(SL_AF_INET, SL_SOCK_DGRAM, (uint32_t) ZERO);
     if (SockID < (int16_t) ZERO)
          return (SOCKET_ERROR);

     Status = sl_SendTo(SockID, packetBuffer, NTP_PACKET_SIZE * sizeof(uint8_t), (uint32_t) ZERO, (SlSockAddr_t *) &Addr, AddrSize);
     if (Status <= (int16_t) ZERO) {
          Status = sl_Close(SockID);
          if (Status < 0)
                return (SEND_ERROR);
          return (SEND_ERROR);
    }

    Status = sl_Close(SockID);
    if (Status < 0)
          return (SEND_ERROR);

    return (STATUS_OK);
}