How can I Always open server?

Question

I have code (my c++ socket server) but I don't know How can I always open. My server will close. when It already send to client It will close itself. But I want it to wait others client and never closed. How can I do it ? Oh I use multi-threaded too.

please,Help me.

and here is my code

int main(void)
{
  HANDLE hThread[3];
  DWORD dwID[3];
  DWORD dwRetVal = 0;

  hThread[0] = CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)ThreadTwo,NULL,0,&dwID[0]);

  dwRetVal = WaitForMultipleObjects(3, hThread, TRUE, INFINITE);

  CloseHandle(hThread[0]);

 return 0;
}

long WINAPI ThreadTwo(long lParam)
{
  WSADATA wsaData;
    SOCKET ListenSocket = INVALID_SOCKET,
           ClientSocket = INVALID_SOCKET;
    struct addrinfo *result = NULL,
                    hints;
    char recvbuf[DEFAULT_BUFLEN];
    int iResult, iSendResult;
    int recvbuflen = DEFAULT_BUFLEN;

    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    hints.ai_flags = AI_PASSIVE;

    iResult = getaddrinfo(NULL, DEFAULT_PORT, &hints, &result);
    if ( iResult != 0 ) {
        printf("getaddrinfo failed with error: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    ListenSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
    if (ListenSocket == INVALID_SOCKET) {
        printf("socket failed with error: %ld\n", WSAGetLastError());
        freeaddrinfo(result);
        WSACleanup();
        return 1;
    }

    iResult = bind( ListenSocket, result->ai_addr, (int)result->ai_addrlen);
    if (iResult == SOCKET_ERROR) {
        printf("bind failed with error: %d\n", WSAGetLastError());
        freeaddrinfo(result);
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }

    freeaddrinfo(result);

    iResult = listen(ListenSocket, SOMAXCONN);
    if (iResult == SOCKET_ERROR) {
        printf("listen failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }

    printf("Waiting for client\n");

    ClientSocket = accept(ListenSocket, NULL, NULL);
    if (ClientSocket == INVALID_SOCKET) {
        printf("accept failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }

    printf("Client acctped.\n");

    closesocket(ListenSocket);

    do {

        iResult = recv(ClientSocket, recvbuf, recvbuflen, 0);
        if (iResult > 0) {
            printf("Bytes received: %d\n", iResult);

            recvbuf[iResult] = '\0';
            printf(recvbuf);

            char* testsend = "222 333\n444 555\n666 777" ;

            iSendResult = send( ClientSocket, testsend , strlen(testsend)+1 , 0 );
            if (iSendResult == SOCKET_ERROR) {
                printf("send failed with error: %d\n", WSAGetLastError());
                closesocket(ClientSocket);
                WSACleanup();
                return 1;
            }
            printf("Bytes sent: %d\n", iSendResult);
        }
        else if (iResult == 0)
            printf("Connection closing...\n");
        else  {
            printf("recv failed with error: %d\n", WSAGetLastError());
            closesocket(ClientSocket);
            WSACleanup();
            return 1;
        }

    } while (iResult > 0);

    iResult = shutdown(ClientSocket, SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed with error: %d\n", WSAGetLastError());
        closesocket(ClientSocket);
        WSACleanup();
        return 1;
    }
    system("pause");

    closesocket(ClientSocket);
    WSACleanup();

  return 0;
}

thank again.

Answer 1

You have to use a loop for that :)

Basically, the server main code must be in a loop, that will go forever ... while you do not stop it.

you should have :

// That's close to pseudo code :)

while(notStoppedByMaster)
{
    // [...]
    ClientSocket = accept(ListenSocket, NULL, NULL);
    handleRequest(ClientSocket);
}

// close the listen socket here

The handleRequest should handle the request in another thread. Be attentive to synchronization :)

my2c

Answer 2

Firstly, it looks like you are creating a console application. If I were you I would create a WIN32 application instead. This means you'll have a GUI but more importantly, a message loop. The message loop allows you to use Asynchronous sockets, it takes a little more understanding but it gives much better and cleaner results.

Read about WSAAsyncSelect: http://msdn.microsoft.com/en-us/library/ms741540%28VS.85%29.aspx Also read socket tutorial: http://msdn.microsoft.com/en-us/library/ms738545%28v=VS.85%29.aspx

Secondly, if you HAVE to use synchronous (blocking) sockets, yes you'll have to be running each on its own thread. You Need to have a loop in which you wait for connections, and then have client sockets like you did, being assigned from your accept(). Then let the client sockets run on their own thread.

Also you are closing your listensocket for some reason in the middle of the code.