[网络协议]Linux下简单的客户端服务器端通信

socket通信过程都不了解的移步：socket通信过程及函数简介

话不多说，上代码

服务器端：

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<errno.h>
#include<ctype.h>

#define BUF_SIZE              1024
#define LISTEN_COUNT          5

typedef struct sockaddr       SOCKADDR;
typedef struct sockaddr_in    SOCKADDR_IN;

int main(int argc, char *argv[])
{
    int listenFd, connFd;
    SOCKADDR_IN serverAddr, clientAddr;
    socklen_t cliAddrLen = sizeof(clientAddr);

    /* 创建监听套接字 */
    if ((listenFd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("Socket error");
        exit(1);
    }

    /* 绑定IP和端口号 */
    memset(&serverAddr, 0, sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(atoi(argv[1])); // argv[1]为端口号参数，atoi()将字符串转为整型，htons()将主机字节序舒徐转换为网络字节序
    serverAddr.sin_addr.s_addr = htonl(INADDR_ANY); // INADDR_ANY代表本机所有IP

    /* 解决bind：Address already in use */
    int val = 1;
    int ret = setsockopt(listenFd, SOL_SOCKET, SO_REUSEADDR, (void *)&val);
    if (ret < 0) {
        perror("Setsockopt error");
        exit(1);
    }

    if (bind(listenFd, (SOCKADDR *)&serverAddr, sizeof(serverAddr)) < 0) {
        perror("Bind error");
        exit(1);
    }

    /* 监听是否有连接请求 */
    if (listen(listenFd, LISTEN_COUNT) < 0) {
        perror("Listen error");
        exit(1);
    }
    printf("Listening...");

    /* 收到连接请求 */
    if ((connFd = accept(listenFd, (SOCKADDR *)&clientAddr, &clientAddrLen)) < 0) {
        perror("Accept error");
        exit(1);
    }
    printf("Accept connection request.");

    while (1) {
        char rdBuf[BUF_SIZE] = {0};
        char wrBuf[BUF_SIZE] = {0};

        /* 读取消息 */
        int rdLen = read(connFd, rdBuf, BUF_SIZE);

        if (rdLen < 0) {
            perror("Read error");
            break;
        } else if (rdLen == 0) {
            printf("The client has been disconnected!");
            close(connFd);
            break;
        }
        printf("Recv buffer：%s\n", rdBuf);
        /* 将收到的消息转为大写 */
        for (int i = 0; i < rdLen; ++i) {
            wrBuf[i] = toupper(rdBuf[i]);
        }
        printf("Send buffer：%s\n", wrBuf);
        write(connFd, wrBuf, rdLen);
    }

    close(listenFd);
    return 0;
}

?客户端：

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<fcntl.h>
#include<string.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<errno.h>

#define BUF_SIZE              1024

typedef struct sockaddr       SOCKADDR;
typedef struct sockaddr_in    SOCKADDR_IN;

int main(int argc, char *argv[])
{
    int connFd;
    SOCKADDR_IN serverAddr;

    /* 创建通信套接字 */
    if ((connFd= socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("Socket error");
        exit(1);
    }

    /* 绑定IP和端口号 */
    memset(&serverAddr, 0, sizeof(serverAddr));
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(atoi(argv[2])); // argv[2]为端口号参数，atoi()将字符串转为整型，htons()将主机字节序舒徐转换为网络字节序
    serverAddr.sin_addr.s_addr = inet_addr(argv[1]); // argv[1]为IP

    connect(connFd, (SOCKADDR *)serverAddr, sizeof(serverAddr));

    while (1) {
        char rdBuf[BUF_SIZE] = {0};
        char wrBuf[BUF_SIZE] = {0};

        printf("Please enter data to send：");
        fgets(wrBuf, BUF_SIZE, stdin)
        write(connFd, wrBuf, BUF_SIZE);

        /* 读取消息 */
        int rdLen = read(connFd, rdBuf, BUF_SIZE);
        if (rdLen < 0) {
            perror("Read error");
            break;
        } else if (rdLen == 0) {
            printf("The server has been disconnected!");
            close(connFd);
            break;
        }
        printf("Recv buffer：%s\n", rdBuf);
    }

    close(connFd);
    return 0;
}

?编译命令：gcc server.c -o server

? ? ? ? ? ? ? ? ? ?gcc client.c -o client

?启动服务器：./server 4004

?启动客户端：./client 0.0.0.0 4004

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