c++ - 使用 Winsock 读取所有信息时结束 "recv()"循环

Question

我在 winsock 的 recv() 循环中遇到问题。我试图在 iResult==0 时终止循环，但是，循环仅在套接字关闭时结束。它似乎卡在 iResult 等于 0 的最后一个 recv() 处。那么关于如何有效终止循环的任何想法？我的最终目标(无论 iResult == 0 与否；也许我做错了)是在读取所有发送的信息后停止循环。这是循环。

    do
    {
        iResult = recv(socket, recvbuf, BUFLEN-1, 0);
        if(iResult > 0){
            // Null byte :)
            // Remove that garbage >:(
            recvbuf[iResult] = '\0';
            printf("Recvbuf: %s\n\n\niResult: %d\n",recvbuf,iResult);
            continue; // working properly
        }
        else if(iResult == 0)
            // Connection closed properly
            break;
        else
        {
            printf("ERROR! %ld",WSAGetLastError());
            break;
        }
    } while(iResult > 0);

就像我说的，我正在接收所有数据，只是无法退出循环。下一步是将数据写回服务器，但它一直卡在这里直到 ping 超时。 Socket为SOCK_STREAM，BUFLEN定义为0x200

谢谢

Answer 1

默认情况下，recv blocks if there's no data to receive 不是返回 0 :

If no incoming data is available at the socket, the recv call blocks and waits for data to arrive according to the blocking rules defined for WSARecv with the MSG_PARTIAL flag not set unless the socket is nonblocking. In this case, a value of SOCKET_ERROR is returned with the error code set to WSAEWOULDBLOCK. The select, WSAAsyncSelect, or WSAEventSelect functions can be used to determine when more data arrives.

您可以使用 ioctlsocket将套接字置于非阻塞模式:

u_long iMode = 1;
ioctlsocket(socket, FIONBIO, &iMode);

编辑:这是我在较早版本中提出的 setsockopt 建议，然后删除(参见评论):

You can use the setsockopt function with the SO_RCVTIMEO option to set the socket to timeout on recv if no data is available.