TCP/IP select并发_tcp select 高并发-优快云博客

本文链接：https://blog.youkuaiyun.com/taozismallmarket/article/details/130045683

该代码示例展示了使用C++进行TCP网络编程的基本步骤，包括创建socket、绑定地址、监听连接、接收客户端请求以及数据的读写。服务器端使用select函数进行多路复用，客户端则进行连接、发送和接收数据。

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server

#include <iostream>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "common.h"
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

using namespace std;

#define SZ 10

int main()
{
    int serv_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (-1 == serv_fd) {
        handle_err("socket");
    }
    sockaddr_in serv_addr, clnt_addr;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(SERV_PORT);
    serv_addr.sin_family = AF_INET;

    {
        int op = true;
        setsockopt(serv_fd, SOL_SOCKET, SO_REUSEADDR, &op, sizeof (op));
    }

    if (-1 == bind(serv_fd, CONST_ADDR_CAST(serv_addr), sizeof (serv_addr))) {
        handle_err("bind");
    }

    if (-1 == listen(serv_fd, 5)) {
        handle_err("listen");
    }

    int max_fd = serv_fd;
    int select_rst, read_len;
    socklen_t clnt_sz = sizeof (clnt_addr);
    fd_set reads, temps;
    FD_ZERO(&reads);
    FD_SET(serv_fd, &reads);
    timeval timeout;

    char msg[SZ] = "";
    while (1) {
        temps = reads;
        timeout.tv_sec = 5;
        timeout.tv_usec = 0;

        select_rst = select(max_fd + 1, &temps, nullptr, nullptr, &timeout);
        if (-1 == select_rst) {
            printf("select error\n");
        } else if (0 == select_rst) {
            printf("timeout\n");
        } else {
            for (int i = 0; i < max_fd + 1; ++i) {
                if (!FD_ISSET(i, &temps)) {
                    continue;
                }
                if (i == serv_fd) {
                    int clnt_fd = accept(serv_fd, nullptr, nullptr);
                    if (-1 == clnt_fd) {
                        printf("connect error\n");
                        continue;
                    }
                    FD_SET(clnt_fd, &reads);
                    if (clnt_fd > max_fd) {
                        max_fd = clnt_fd;
                    }
                } else {
                    memset(&clnt_addr, 0, clnt_sz);
                    getpeername(i, ADDR_CAST(clnt_addr), &clnt_sz);
                    printf("msg from: %s:%d\n", inet_ntoa(clnt_addr.sin_addr), ntohs(clnt_addr.sin_port));
                    while (1) {
                        read_len = read(i, msg, SZ);
                        if (read_len == 0) {
                            FD_CLR(i, &reads);
                            close(i);
                            break;
                        }
                        msg[read_len] = 0;
                        printf("msg: %s\n", msg);
                        if (0 <= (read_len = recv(i, msg, SZ, MSG_PEEK | MSG_DONTWAIT))) { //处理数据边界，一次给输入打完，这里写的不好
                            read_len = read(i, msg, SZ);
                            msg[read_len] = 0;
                            printf("msg: %s\n", msg);
                            break;
                        }
                        break;
                    }

                    char reply_str[30];
                    sprintf(reply_str, "server recieve: %c\n", msg[0]);
                    write(i, reply_str, strlen(reply_str));
                }
            }
        }
    }

    return 0;
}

client

#include <iostream>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "common.h"
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#define SZ 30

int main() {
    int sock_fd = socket(AF_INET, SOCK_STREAM, 0);
    sockaddr_in serv_addr;
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(SERV_PORT);

    if (-1 == connect(sock_fd, CONST_ADDR_CAST(serv_addr), sizeof (serv_addr))) {
        handle_err("connect");
    }

    sockaddr_in clnt_addr;
    socklen_t clnt_sz = sizeof (clnt_addr);
    getsockname(sock_fd, ADDR_CAST(clnt_addr), &clnt_sz);
    printf("client is: %s:%d\n", inet_ntoa(clnt_addr.sin_addr), ntohs(clnt_addr.sin_port));

    getpeername(sock_fd, ADDR_CAST(clnt_addr), &clnt_sz);
    printf("server is: %s:%d\n", inet_ntoa(clnt_addr.sin_addr), ntohs(clnt_addr.sin_port));


    char msg[SZ];
    int read_len;
    while (1) {
        read_len = read(0, msg, SZ);
        write(sock_fd, msg, read_len);
        read_len = read(sock_fd, msg, SZ);
        write(1, msg, read_len);
    }
    return 1;
}

common.h

#ifndef COMMON_H
#define COMMON_H

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

#define SERV_PORT 9999
#define CONST_ADDR_CAST(addr) const_cast<sockaddr *>(ADDR_CAST(addr))
#define ADDR_CAST(addr) reinterpret_cast<sockaddr *>(&addr)

void handle_err(const char *msg) /*__attribute__((noreturn))*/ {
    printf("errro: %s\n", msg);
    exit(1);
}

#endif // COMMON_H