请问C++如何进行telnet操作?

Question

例如目标机器的IP是 192.168.1.100， 用户名abc ， 密码333

怎么通过代码登录并且获取返回值user:?

Answer 1

C++语言默认库中不支持telnet操作，如果想要使用则可以通过boost库来实现，或者使用Windows提供的套接字接口自己实现该功能，例如有如下这样的一段代码；

void telnet(const char* host, const char* port)
{
    WSADATA wsaData;
    SOCKET ConnectSocket = INVALID_SOCKET;
    struct addrinfo* result = NULL, * ptr = NULL, hints;
    int iResult;
    char recvbuf[512];
    int recvbuflen = 512;

    iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0)
    {
        std::cerr << "WSAStartup failed with error: " << iResult << std::endl;
        return;
    }

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    iResult = getaddrinfo(host, port, &hints, &result);
    if (iResult != 0)
    {
        std::cerr << "getaddrinfo failed with error: " << iResult << std::endl;
        WSACleanup();
        return;
    }

    for (ptr = result; ptr != NULL; ptr = ptr->ai_next)
    {
        ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
        if (ConnectSocket == INVALID_SOCKET)
        {
            std::cerr << "socket failed with error: " << WSAGetLastError() << std::endl;
            WSACleanup();
            return;
        }

        iResult = connect(ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
        if (iResult == SOCKET_ERROR)
        {
            closesocket(ConnectSocket);
            ConnectSocket = INVALID_SOCKET;
            continue;
        }
        break;
    }

    freeaddrinfo(result);

    if (ConnectSocket == INVALID_SOCKET)
    {
        std::cerr << "Unable to connect to server!" << std::endl;
        WSACleanup();
        return;
    }

    do {
        iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
        if (iResult > 0)
        {
            std::cout.write(recvbuf, iResult);
            std::cout.flush();

            std::string message;
            std::getline(std::cin, message);
            message += "\n";

            iResult = send(ConnectSocket, message.c_str(), (int)message.length(), 0);
            if (iResult == SOCKET_ERROR)
            {
                std::cerr << "send failed with error: " << WSAGetLastError() << std::endl;
                closesocket(ConnectSocket);
                WSACleanup();
                return;
            }
        } else if (iResult == 0)
            std::cout << "Connection closed\n";
        else
            std::cerr << "recv failed with error: " << WSAGetLastError() << std::endl;

    } while (iResult > 0);

    closesocket(ConnectSocket);
    WSACleanup();
}

你只需要传入两个参数，IP地址和端口字符串，就可以实现telnet访问目标主机的功能。