recvfrom的（）错误10035使用非阻塞套接字

Question

我使用ioctlsocket（）函数，使我的插座非阻塞的，但是当我打电话recvfrom的（），我得到的错误10035（WSAEWOULDBLOCK）。

u_long mode = 1; 
ioctlsocket(newSocketIdentifier, FIONBIO, &mode); 

while(1) 
    { 
     if((recv_len = recvfrom(newSocketIdentifier, receiveBuffer, sizeof(receiveBuffer), 0, (struct sockaddr *) &clientSocket, &clientSocketLength)) == SOCKET_ERROR) 
     { 
     char err[128]; 
     itoa(WSAGetLastError(),err,10); 
     MessageBox(NULL,"Could not Receive Data",err,MB_ICONINFORMATION); 
     BREAK; 
     } 
    } 

任何人都可以解释为什么发生这种情况？ :(

Answer 1

这是正常的，如果没有数据可用，该代码是WSAEWOULDBLOCK（见表格）和手段，即阻塞端口的功能将不得不坐下来等待，直到它可以提供服务。

while(1) 
    { 
     if((recv_len = recvfrom(newSocketIdentifier, receiveBuffer, sizeof(receiveBuffer), 0, (struct sockaddr *) &clientSocket, &clientSocketLength)) == SOCKET_ERROR) 
     { 
     int ierr= WSAGetLastError(); 
     if (ierr==WSAEWOULDBLOCK) { // currently no data available 
      Sleep(50); // wait and try again 
      continue; 
     } 

     // Other errors 
     char err[128]; 
     itoa(ierr,err,10); 
     MessageBox(NULL,"Could not Receive Data",err,MB_ICONINFORMATION); 
     break; 
     } 
    }