C++ Socket通讯连接Server，并可设置连接超时时间

Socket通讯连接Server，并可设置连接超时时间

非阻塞模式：使用 ioctlsocket 将 socket 设置为非阻塞模式，这样 connect 调用不会阻塞主线程。
连接线程：在一个新线程中执行连接操作，使用 std::atomic 来检查连接是否成功。
超时逻辑：主线程使用一个循环来检查连接是否成功，若超出设定的超时时间则退出。

#include <iostream>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <thread>
#include <atomic>

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


void ThreadConnect(SOCKET sock, struct sockaddr_in* server, std::atomic<bool>& connected)
{
    if (connect(sock, (struct sockaddr*)server, sizeof(*server)) == SOCKET_ERROR)
    {
        connected = false;
    }
    else
    {
        connected = true;
    }
}

bool ConnectServer()
{
    WSADATA wsaData;
    SOCKET sock;
    struct sockaddr_in server;

    // 初始化 Winsock
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
    {
        std::cerr << "Failed to initialize Winsock. Error: " << WSAGetLastError() << std::endl;
        return false;
    }

    // 创建 socket
    sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock == INVALID_SOCKET)
    {
        std::cerr << "Could not create socket. Error: " << WSAGetLastError() << std::endl;
        WSACleanup();
        return false;
    }

    // 设置 socket 为非阻塞模式
    u_long mode = 1; // 1 表示非阻塞模式
    ioctlsocket(sock, FIONBIO, &mode);

    // 配置服务器地址
    server.sin_family = AF_INET;
    server.sin_port = htons(7999); // 服务器端口
    inet_pton(AF_INET, "127.0.0.1", &server.sin_addr); // 服务器地址

    std::atomic<bool> connected(false);
    std::thread connectThread(ThreadConnect, sock, &server, std::ref(connected));

    // 等待连接或超时
    int connecTimeout = 1000;

    DWORD startTime = GetTickCount();
    while (GetTickCount() - startTime < connecTimeout)
    {
        if (connected)
        {
            break;
        }
        Sleep(100);
    }   
    connectThread.join(); // 关闭连接线程

    std::cout << "Connection time: " << (GetTickCount() - startTime) << " ms" << std::endl;

    if (!connected)
    {
        std::cerr << "Connection timeout." << std::endl;
        closesocket(sock);
        WSACleanup();

        return false;
    }

    mode = 0; // 设置为阻塞模式
    ioctlsocket(sock, FIONBIO, &mode);

    std::cout << "Connected to server!" << std::endl;


    int sendTimeout = 1000; // 发送超时设置
    int recvTimeout = 1000; // 接收超时设置

    if (setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, (const char*)&sendTimeout, sizeof(sendTimeout)) < 0)
    {
        std::cerr << "Failed to set send timeout. Error: " << WSAGetLastError() << std::endl;
        closesocket(sock);
        WSACleanup();
        return false;
    }

    if (setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (const char*)&recvTimeout, sizeof(recvTimeout)) < 0)
    {
        std::cerr << "Failed to set receive timeout. Error: " << WSAGetLastError() << std::endl;
        closesocket(sock);
        WSACleanup();
        return false;
    }

    // 这里可以添加发送和接收数据的代码

    // 关闭 socket
    closesocket(sock);
    WSACleanup();

    return true;
}

int main()
{

    ConnectServer();

    std::cin.get();

    return 0;
}