c - 我无法在 Windows 7 上设置服务器来监听特定端口

Question

我想使用 winapi 学习一些 C 网络编程。

这就是代码。问题。它仅在端口 5555 上运行，而不是我指定的端口。它编译并运行。 Windows 防火墙弹出，我授权该应用程序。我使用 connect() 参数使用 nmap 扫描了我的计算机，它关闭了连接，确保该应用程序正在端口 5555 上运行。然而，它不会在屏幕上显示任何内容，除非连接终止。

注释部分是我尝试设置服务器的另一种方式。我尝试了两种方法，但都效果不佳。提前致谢。

#undef UNICODE

#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>

// Need to link with Ws2_32.lib
// #pragma comment (lib, "Mswsock.lib")

#define DEFAULT_BUFLEN 1024

int __cdecl main(void)
{
    WSADATA wsaData;
    int iResult;

SOCKET ListenSocket = INVALID_SOCKET;
SOCKET ClientSocket = INVALID_SOCKET;

struct addrinfo *result = NULL;
struct addrinfo hints;

int iSendResult;
char recvbuf[DEFAULT_BUFLEN];
int recvbuflen = DEFAULT_BUFLEN;

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

struct sockaddr_in my_addr, *p;

//ZeroMemory(&hints, sizeof(hints));
my_addr.sin_family = AF_INET;
my_addr.sin_addr.s_addr = inet_addr(192.168.0.102)
my_addr.sin_port = htons(9998);
memset(my_addr.sin_zero,'\0', sizeof(my_addr.sin_zero));
/*
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
hints.ai_flags = AI_PASSIVE;
*/  

// Resolve the server address and port

/*iResult = getaddrinfo("192.168.0.102", "3222", &hints, &result);
if ( iResult != 0 ) {
    printf("getaddrinfo failed with error: %d\n", iResult);
    WSACleanup();
    return 1;
}*/

//Create a SOCKET for connecting to server
ListenSocket = socket(p->sin_family, p->sin_socktype, p->sin_protocol);

//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;
}

// Setup the TCP listening socket
iResult = bind( ListenSocket, 192.168.0.102, (int)p->sin_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;
}

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

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

// Receive until the peer shuts down the connection
do {

    printf("Running on port: %d\n", p->sin_port)

    iResult = recv(ClientSocket, recvbuf, recvbuflen, 0);
    if (iResult > 0) {
        printf("Bytes received: %d\n", iResult);
    // Echo the buffer back to the sender
        iSendResult = send( ClientSocket, recvbuf, iResult, 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);

// shutdown the connection since we're done
iResult = shutdown(ClientSocket, SD_SEND);
if (iResult == SOCKET_ERROR) {
    printf("shutdown failed with error: %d\n", WSAGetLastError());
    closesocket(ClientSocket);
    WSACleanup();
    return 1;
}

// cleanup
closesocket(ClientSocket);
WSACleanup();

return 0;
}

Answer 1

您的代码中有很多错误。

试试这个:

#undef UNICODE

#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <winsock2.h>
#include <stdlib.h>
#include <stdio.h>

// Need to link with Ws2_32.lib
// #pragma comment (lib, "Mswsock.lib")

#define DEFAULT_BUFLEN 1024

int __cdecl main(void)
{
    WSADATA wsaData;
    int iResult;

    SOCKET ListenSocket = INVALID_SOCKET;
    SOCKET ClientSocket = INVALID_SOCKET;

    int iSendResult;
    char recvbuf[DEFAULT_BUFLEN];

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

    struct sockaddr_in my_addr;

    short my_port = 9998;

    memset(&my_addr, 0, sizeof(my_addr));
    my_addr.sin_family = AF_INET;
    my_addr.sin_addr.s_addr = inet_addr("192.168.0.102");
    my_addr.sin_port = htons(my_port);

    // Resolve the server address and port

    //Create a SOCKET for connecting to server
    ListenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (ListenSocket == INVALID_SOCKET)
    {
        printf("socket failed with error: %ld\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    // Setup the TCP listening socket
    iResult = bind(ListenSocket, (struct sockaddr*)&my_addr, sizeof(my_addr));
    if (iResult == SOCKET_ERROR)
    {
        printf("bind failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }

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

    printf("Listening on port: %hd\n", my_port);

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

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

    printf("Client connected\n");

    // Receive until the peer shuts down the connection
    do
    {
        iResult = recv(ClientSocket, recvbuf, sizeof(recvbuf), 0);
        if (iResult > 0)
        {
            printf("Bytes received: %d\n", iResult);
            // Echo the buffer back to the sender
            iSendResult = send( ClientSocket, recvbuf, iResult, 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");
            break;
        }
        else 
        {
            printf("recv failed with error: %d\n", WSAGetLastError());
            closesocket(ClientSocket);
            WSACleanup();
            return 1;
        }
    }
    while (true);

    // shutdown the connection since we're done
    iResult = shutdown(ClientSocket, SD_SEND);
    if (iResult == SOCKET_ERROR)
    {
        printf("shutdown failed with error: %d\n", WSAGetLastError());
        closesocket(ClientSocket);
        WSACleanup();
        return 1;
    }

    // cleanup
    closesocket(ClientSocket);
    WSACleanup();

    return 0;
}

或者这个:

#undef UNICODE

#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>

// Need to link with Ws2_32.lib
// #pragma comment (lib, "Mswsock.lib")

#define DEFAULT_BUFLEN 1024

int __cdecl main(void)
{
    WSADATA wsaData;
    int iResult;

    SOCKET ListenSocket = INVALID_SOCKET;
    SOCKET ClientSocket = INVALID_SOCKET;

    struct addrinfo *result = NULL;
    struct addrinfo hints;

    int iSendResult;
    char recvbuf[DEFAULT_BUFLEN];

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

    short my_port = 9998;
    char my_port_str[6];
    sprintf(my_port_str, "%hu", my_port);

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    hints.ai_flags = AI_PASSIVE;

    // Resolve the server address and port

    iResult = getaddrinfo("192.168.0.102", my_port_str, &hints, &result);
    if (iResult != 0)
    {
        printf("getaddrinfo failed with error: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    //Create a SOCKET for connecting to server
    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;
    }

    // Setup the TCP listening socket
    iResult = bind(ListenSocket, result->ai_addr, 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("Listening on port: %hd\n", my_port);

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

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

    printf("Client connected\n");

    // Receive until the peer shuts down the connection
    do
    {
        iResult = recv(ClientSocket, recvbuf, sizeof(recvbuf), 0);
        if (iResult > 0)
        {
            printf("Bytes received: %d\n", iResult);
            // Echo the buffer back to the sender
            iSendResult = send(ClientSocket, recvbuf, iResult, 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");
            break;
        }
        else
        {
            printf("recv failed with error: %d\n", WSAGetLastError());
            closesocket(ClientSocket);
            WSACleanup();
            return 1;
        }
    }
    while (true);

    // shutdown the connection since we're done
    iResult = shutdown(ClientSocket, SD_SEND);
    if (iResult == SOCKET_ERROR)
    {
        printf("shutdown failed with error: %d\n", WSAGetLastError());
        closesocket(ClientSocket);
        WSACleanup();
        return 1;
    }

    // cleanup
    closesocket(ClientSocket);
    WSACleanup();

    return 0;
}