听 Winsock 错误 10022

Question

我正在制作一个小型 IRC 服务器，但我遇到了一个问题；在尝试侦听套接字时，我收到错误 10022（无效参数）。

accept() 上也出现错误，但这是因为套接字未在侦听（我发布的问题是关于此问题）。

我没有包含接受功能，因为我觉得它没有必要并且会添加毫无意义的代码。

#include <iostream>
#include <ws2tcpip.h>
#include <winsock2.h>
#include <thread>
#include <string>
#pragma comment(lib, "Ws2_32.lib")
#define maxConnections 10
class Server
{
        struct sockaddr_storage their_addr;
        struct addrinfo hints, *res;
        struct addrinfo *servinfo;
    int status;
    SOCKET sock;
public:
    void Start(const char *port);
};

void Server::Start(const char *port)
{
    WSADATA WSAData;
    if (WSAStartup(MAKEWORD(2, 0), &WSAData) != 0)
    {
        std::cout << "[ERROR]: " << GetLastError() << ".\n";
    }
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    status = getaddrinfo(NULL, port, &hints, &res);
    sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
    if (sock == SOCKET_ERROR)
    {
        std::cout << "[ERROR]: " << WSAGetLastError() << "Bad Socket.\n";
    }
    bind(sock, res->ai_addr, res->ai_addrlen);

错误：

    if (listen(sock, maxConnections) == SOCKET_ERROR)
    {
        std::cout << "[ERROR]: " << WSAGetLastError() << " Listening Failed.\n";
    }

上面的代码详细说明了socket的创建和绑定，都成功了（虽然不一定对）。包括“NULL”在内的套接字创建可能是问题所在。

谢谢:)

Answer 1

WSAStartup() 和getaddrinfo() 不使用(WSA)GetLastError()，而是直接返回实际的错误代码。您没有在错误消息中考虑到这一点。

socket() 在失败时返回 INVALID_SOCKET，而不是 SOCKET_ERROR。

使用getaddrinfo()创建监听套接字时，应在hints参数的addrinfo.ai_flags字段中指定AI_PASSIVE。这将使用适合传递给bind() 的数据填充输出addrinfo。

试试这样的：

class Server
{
private:
    bool winsockStarted;
    SOCKET sock;
    ...
public:
    Server();
    ~Server();
    bool Start(const char *port);
    void Stop();
    ...
};

Server::Server()
    : sock(INVALID_SOCKET), winsockStarted(false)
{
    WSADATA WSAData = {0};
    int status = WSAStartup(MAKEWORD(2, 0), &WSAData);
    if (status != 0)
        std::cout << "[ERROR]: " << status << " Unable to start Winsock." << std::endl;
    else
        winsockStarted = true;
}

Server::~Server()
{
    Stop();

    if (winsockStarted)
        WSACleanup();
}

bool Server::Start(const char *port)
{
    Stop();

    struct addrinfo hints = {0};
    struct addrinfo *res = NULL;

    hints.ai_flags = AI_PASSIVE;
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    int status = getaddrinfo(NULL, port, &hints, &res);
    if (status != 0)
    {
        std::cout << "[ERROR]: " << status << " Unable to get address info for Port " << port << "." << std::endl;
        return false;
    }

    SOCKET newsock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
    if (newsock == INVALID_SOCKET)
    {
        std::cout << "[ERROR]: " << WSAGetLastError() << " Unable to create Socket." << std::endl;
        freeaddrinfo(res);
        return false;
    }

    if (bind(newsock, res->ai_addr, res->ai_addrlen) == SOCKET_ERROR)
    {
        std::cout << "[ERROR]: " << WSAGetLastError() << " Unable to bind Socket." << std::endl;
        freeaddrinfo(res);
        closesocket(newsock);
        return false;
    }

    freeaddrinfo(res);

    if (listen(newsock, maxConnections) == SOCKET_ERROR)
    {
        std::cout << "[ERROR]: " << WSAGetLastError() << " Unable to Listen on Port " << port << "." << std::endl;
        closesocket(newsock);
        return false;
    }

    sock = newsock;
    return true;
}

void Server::Stop()
{
    if (sock != INVALID_SOCKET)
    {
        closesocket(sock);
        sock = INVALID_SOCKET;
    }
}

Answer 2

我重新阅读了我的代码并意识到我需要在这里添加一个检查

status = getaddrinfo(NULL, port, &hints, &res); 

我改成

if (status = getaddrinfo(NULL, port, &hints, &res) != 0)
{
    std::cout << "[ERROR]: " << WSAGetLastError() << "Get Address Info failed.\n";
}

并且启动成功。

如果有人能解释原因，我会改进我的答案。