网络编程 — Windows TCP服务端和客户端

1. 服务端

#include <iostream>
#include <signal.h>
#include <forward_list>
#include <thread>
#include <WinSock2.h>
#include <Windows.h>
#pragma comment(lib, "Ws2_32.lib")

class Server {
    constexpr static int DEFAULT_BACKLOG = 10;
public:
    Server(): _listener(INVALID_SOCKET), _should_exit(false) {}
    ~Server() {
        for (auto it = _threads.begin(); it != _threads.end(); it++) {
            it->join();
        }
    }

    // 判断 server 是否有效
    operator bool() const {
        return _listener != INVALID_SOCKET;
    }

    // 监听并接受客户端连接
    void listen_and_serve(unsigned short port, int backlog= DEFAULT_BACKLOG) {
        // 初始化 WSA
        WORD socketVersion = MAKEWORD(2, 2);
        WSADATA wsaData;
        if (WSAStartup(socketVersion, &wsaData) != 0) {
            std::cerr << "cannot start up\n";
            return;
        }

        // 创建套接字
        _listener = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        if (_listener == INVALID_SOCKET) {
            std::cerr << "cannot create listener\n";
            return;
        }

        // 设置套接字选项
        int value = 1;
        if (setsockopt(_listener, SOL_SOCKET, SO_REUSEADDR, (char*)&value, sizeof(value)) == SOCKET_ERROR) {
            std::cerr << "cannot set option: reuse_address\n";
        }

        // 绑定地址
        memset(&addr, 0, sizeof(sockaddr_in));
        sockaddr_in addr;
        addr.sin_family = AF_INET;
        addr.sin_port = htons(port);
        addr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
        if (bind(_listener, (LPSOCKADDR)&addr, sizeof(addr)) == SOCKET_ERROR) {
            std::cerr << "bind failed\n";
            return;
        }

        // 监听连接
        if (listen(_listener, backlog) == SOCKET_ERROR) {
            std::cerr << "listen failed\n";
            return;
        }

        SOCKET conn;
        std::cout << "listening ...\n";

        // 接受连接
        while (!_should_exit) {
            conn = accept(_listener, NULL, NULL);
            if (conn == INVALID_SOCKET) {
                std::cerr << "accept failed\n";
            }

            // 启动线程去处理客户端连接
            _threads.push_front(std::thread(SetServer::handle_connection, conn));
        }
    }

    // 关闭、完成善后工作
    void close() {
        _should_exit = true;
        closesocket(_listener);
        WSACleanup();
    }

    // 处理客户端连接
    static void handle_connection(SOCKET conn) {
        char buf[16] = { 0 };
        int n = recv(conn, buf, sizeof(buf), 0);
        send(conn, buf, n, 0);
        closesocket(conn);
    }

private:
    SOCKET _listener;
    std::forward_list<std::thread> _threads;
    bool _should_exit;
};

Server server;

// 信号处理器
void handler(int signum) {
    std::cout << "exit ...\n";
    if (server) {
        server.close();
    }
    exit(EXIT_SUCCESS);
}

int main() {
    // 处理 ctrl+c
    signal(SIGINT, handler);

    server.listen_and_serve(6666);
}

2. 客户端

#pragma once

#include <iostream>
#include <WS2tcpip.h>
#include <WinSock2.h>
#include <Windows.h>
#pragma comment(lib, "Ws2_32.lib")

const char* SERVER_IP = "127.0.0.1";
const short SERVER_PORT = 6666;

int main() {
    // 初始化 WSA
    WORD socketVersion = MAKEWORD(2, 2);
    WSADATA wsaData;
    if (WSAStartup(socketVersion, &wsaData) != 0) {
        std::cerr << "cannot start up\n";
        return 1;
    }

    // 创建套接字
    SOCKET sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (sock == INVALID_SOCKET) {
        std::cerr << "cannot create socket\n";
        return 1;
    }

    // 发起连接
    sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, SERVER_IP, &addr.sin_addr);
    if (connect(sock, (LPSOCKADDR)&addr, sizeof(addr)) == SOCKET_ERROR) {
        std::cerr << "connect failed\n";
        return 1;
    }

    // 发送、接收数据
    const char* msg = "hello";
    char buf[16] = { 0 };
    send(sock, msg, strlen(msg), 0);
    int n = recv(sock, buf, sizeof(buf), 0);
    std::cout << buf << std::endl;

    closesocket(sock);
    return 0;
}

参考资料

https://blog.csdn.net/weixinhum/article/details/81742248