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Linux网络编程socket服务器端模拟实现

news 2025/7/30 20:55:21

TCP通信流程分析:
server 服务器端主要流程
socket()，创建socket套接字
bind()，绑定ip和端口
listen(),设置监听上限，不是用来监听的
accept()，阻塞客户端监听连接
用转换大小写字符串为例子

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

#define SERV_PORT 9527

void sys_err(char* str)
{
    perror(str);
    exit(1);
}

int main(int argc,char* argv[])
{
    int lfd = 0,cfd = 0;
    int ret_bind;
    int ret_listen;
    int ret_accept;
    int ret_read;
    char buf[BUFSIZ];
    socklen_t clit_addr_len;
    struct sockaddr_in serv_addr,clit_addr;
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(SERV_PORT);
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    lfd = socket(AF_INET,SOCK_STREAM,0);
    if(lfd == -1)
    {
        sys_err("socket error");
    }
    ret_bind = bind(lfd,(struct sockaddr*)&serv_addr,sizeof(serv_addr));
    if(ret_bind == -1)
    {
        sys_err("bind error");
    }
    ret_listen = listen(lfd,128); //The default maximum value is 128
    clit_addr_len = sizeof(clit_addr);
    ret_accept = accept(lfd,(struct sockaddr*)&clit_addr,&clit_addr_len);
    if(ret_accept == -1)
    {
        sys_err("accept error");
    }

    while(1)
    {
        ret_read = read(ret_accept,buf,sizeof(buf));
        write(STDOUT_FILENO,buf,ret_read);
        for(int i = 0;i < ret_read;i++)
        {
            buf[i] = toupper(buf[i]);
        }
        write(ret_accept,buf,ret_read);
    } 
    
    close(lfd);
    close(ret_accept);

    return 0;
}