c++ - 如何获得规范套接字的 "CLOSE_WAIT"状态

Question

我在 Visual Studio 2010 上使用 VC++。
现在我遇到了一些问题。我认为这是一个愚蠢的问题，但我想得到一个明确的答案。

如何获得所选 SOCKET 的 CLOSE_WAIT 状态？

// SocketThreadConn.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <WinSock.h>
#include <Windows.h>

#pragma comment(lib, "ws2_32.lib")

#define PR_RECORED_TIME 10*1000 // (ms)

BYTE* pByteCamData = NULL;
INT nHeight = 900;
INT nWidth = 1600;
INT nSpect = 3;
INT nSolution = nHeight * nWidth * nSpect;

VOID SendRecoredData(SOCKET socket2operation);

int _tmain(int argc, _TCHAR* argv[])
{
    pByteCamData = new BYTE[nSolution]; // <-- use [], not ()!

    //----------------------
    // Initialize Winsock.
    WSADATA wsaData;
    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != NO_ERROR) {
        wprintf(L"WSAStartup failed with error: %d\n", iResult);
        delete[] pByteCamData;
        return 1;
    }

    //----------------------
    // Create a SOCKET for listening for
    // incoming connection requests.
    SOCKET ListenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (ListenSocket == INVALID_SOCKET) {
        wprintf(L"socket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        delete[] pByteCamData;
        return 1;
    }

    //----------------------
    // The sockaddr_in structure specifies the address family,
    // IP address, and port for the socket that is being bound.
    sockaddr_in service = {};
    service.sin_family = AF_INET;
    service.sin_addr.s_addr = INADDR_ANY;   // inet_addr("127.0.0.1");
    service.sin_port = htons(27015);

    if (bind(ListenSocket, (SOCKADDR *) &service, sizeof(service)) == SOCKET_ERROR) {
        wprintf(L"bind failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        delete[] pByteCamData;
        return 1;
    }

    //----------------------
    // Listen for incoming connection requests.
    // on the created socket
    if (listen(ListenSocket, 1) == SOCKET_ERROR) {
        wprintf(L"listen failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        delete[] pByteCamData;
        return 1;
    }

    //----------------------
    // Accept the connection.
    wprintf(L"Waiting for client to connect...\n");
    SOCKET AcceptSocket = accept(ListenSocket, NULL, NULL);
    if (AcceptSocket == INVALID_SOCKET) {
        wprintf(L"accept failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        delete[] pByteCamData;
        return 1;
    }

    wprintf(L"Client connected.\n");
    SendRecoredData(AcceptSocket); // <-- logic fix!

    // No longer need client socket
    closesocket(AcceptSocket); // <-- CLOSE_WAIT fix!

    // No longer need server socket
    closesocket(ListenSocket);

    WSACleanup();

    delete[] pByteCamData;

    return 0;
}

VOID SendRecoredData(SOCKET socket2operation)
{
    if(IsSocketAlive(socket2operation) == 0)
        return;

    INT nCountDown = 5;
    INT nSentData, nNumToSend;
    BYTE *pData;

    do
    {
        if (nCountDown == 0)
        {
            nCountDown = 5;

            pData = pByteCamData;
            nNumToSend = nSolution;

            while (nNumToSend > 0) <-- send() fix!
            {
                nSentData = send(socket2operation, (char*)pData, nNumToSend, 0);
                if (SOCKET_ERROR == nSentData) {
                    wprintf(L"send failed with error: %d\n", WSAGetLastError());
                    return;
                }
                pData += nSentData;
                nNumToSend -= nSentData;
            }

            wprintf(L"Sent Camera Data OK [%d] Bytes\n", nSolution);
        }

        Sleep(PR_RECORED_TIME);
        --nCountDown;
    }
    while (TRUE);
}
INT IsSocketAlive(SOCKET socket2check)
{
    if (socket2check == INVALID_SOCKET)
        return FALSE;

    INT nError_code = -1;
    INT nError_code_size = sizeof(nError_code);
    INT nRetValue = getsockopt(socket2check, SOL_SOCKET, SO_ERROR, (CHAR*)&nError_code, &nError_code_size);

//  if (nRetValue != -1)
    {
        //      _tprintf(_T("Error getting socket error code : %d \n"), strerror(nRetValue));
    }

    if (nError_code != 0)
    {
        _tprintf(_T("Socket error : %d \n"), strerror(nError_code));
    }

    switch (nError_code)
    {
    case 0:
        return TRUE;
        break;
    case SOCKET_ERROR:
        return FALSE;
    default:
        return FALSE;
    }
}

问题是 CLOSE_WAIT 'ed' 套接字被检查为事件套接字。
当 SocketThreadConn.exe 正在处理 while 循环 时，它不会中断循环 尽管 Listen socket 是 CLOSE_WAIT。

如何检查接受的套接字是否ESTABLISHED？

(此代码已被@Remy Lebeau 更改)

我如何检查套接字是否仍然是 ESTABLISHED，而不是使用 send() 或 GetTcpTable()。

函数 GetTcpTable() 运行良好，但我必须仅使用它们的值 (USHORT) 来查找套接字。 MIB_TCPTABLE 中没有套接字值字段。

Answer 1

#define SOCKET_ALIVE 10
#define SOCKET_DEAD 9

INT CheckSocketAlive(SOCKET socket2check)
{
    fd_set  fdR;
    struct  timeval timeout;
    timeout.tv_sec = 1;
    timeout.tv_usec = 0;
    FD_ZERO(&fdR);  
    FD_SET(socket2check, &fdR);
    switch (select(socket2check + 1, &fdR, NULL,NULL, &timeout))
    {  
    case SOCKET_ERROR:
        _tprintf(_T("\tError condition. Code : [%d]\n"), WSAGetLastError());
        return SOCKET_DEAD;
    case 0:
        return SOCKET_ALIVE;
    default:
        if ( FD_ISSET(socket2check, &fdR) )
        {
            _tprintf(_T("A read event has occurred on socket [socket2check].\n"));
            return SOCKET_DEAD;
        }
        break;
    }
}

您可以使用此函数获取所选套接字的状态。
但只有 SOCKET_ERROR 或 SOCKET_ALIVE。
您可以根据需要更改 timeout.tv_sec (1sec)。