Question

我正在学习Windows中的套接字，也是HTTP协议。所以我正在做一些保持活着的测试，但由于某种原因，recv挂起约5秒钟，这里是：

VOID TestWinsock()
{
    WSADATA WsaData;
    addrinfo hints;
    addrinfo* hResult;
    SOCKET hsocket;
    int Result;

    WSAStartup(MAKEWORD(2, 2), &WsaData);
    RtlZeroMemory(&hints, sizeof(hints));

    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    Result = getaddrinfo("localhost", "80", &hints, &hResult);
    if (Result != 0)
    {
        return;
    }

    hsocket = socket(hResult->ai_family, hResult->ai_socktype, hResult->ai_protocol);
    if (hsocket == INVALID_SOCKET)
    {
        return;
    }

    Result = connect(hsocket, hResult->ai_addr, (int)hResult->ai_addrlen);
    if (Result == SOCKET_ERROR)
    {
        return;
    }

    char* POSTContent;
    char HTTPRequestBuffer[1024];
    char RecvBuffer[1024];

    char* HTTPRequest =
        "POST %s HTTP/1.0\r\n"
        "Host: %s\r\n"
        "connection: keep-alive\r\n"
        "Content-type: application/x-www-form-urlencoded\r\n"
        "Content-Length: %u\r\n"
        "\r\n"
        "%s"
        "\r\n"
        "\r\n";

    POSTContent = "variable1=10";
    wsprintfA(
        HTTPRequestBuffer,
        HTTPRequest,
        "/tests/test.php",
        "127.0.0.1",
        strlen(POSTContent),
        POSTContent
        );

    int sent = send(hsocket, HTTPRequestBuffer, strlen(HTTPRequestBuffer), 0);
    RtlZeroMemory(RecvBuffer, sizeof(RecvBuffer));

    // here recv blocks for about 5 seconds, yeah, it reads only 100 bytes, tried with something like sizeof(RecvBuffer) as well.
    recv(hsocket, RecvBuffer, 100, 0);

    ....
}

我想知道如何解决这个问题，或者哪个是使用keep-alive的正确方法。

Answer 1

在您的HTTP请求中，您发送的额外\r\n\r\n未包含在Content-Length中，因此数据和宣布的长度不匹配。 HTTP标准说：

在消息正文的消息中给出Content-Length时允许，其字段值必须与OCTET的数量完全匹配消息体。

MUST很重要，这意味着服务器完全有权拒绝您的请求。您指定keep-alive的事实也可能意味着服务器等待下一个有效请求。由于您只发送4个字节，服务器最终会在5s后关闭连接，并且可能发送错误（这部分只是关于实际发生的事情的推测）。

具有保持活动（HTTP）的recv功能块

1 个答案: