传统的网络编程（分三步一步一步的写）

水深无声 2022-05-16 12:55 259阅读 0赞

##### server #####

#include <sys/types.h>
    #include <sys/socket.h>
    #include <ctype.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <stdlib.h>
    #include <sys/wait.h>
    #include <unistd.h>
    #include <stdio.h>
    
    #define MAX_READ_MSG_LEN 4096
    #define MAX_WRITE_MSG_LEN 4096 
    
    const   short       g_nConnectPort = 15623;
    const char* g_szUserMsg="Hi,I'm server!";
    
    typedef struct sockaddr SA;
    typedef struct sockaddr_in SA4;
    
    void do_work(int fd) 
    {
    #if 1
        int r,i;
        char buf[MAX_READ_MSG_LEN];
        //读取数据
        r = read(fd,buf,MAX_READ_MSG_LEN);
        //处理数据
        write(1, buf, r);
        //响应客户端
        write(fd, g_szUserMsg, MAX_WRITE_MSG_LEN);
    #endif
        return;
    }
    
    int main() 
    {
        int s_fd;
        int c_fd;
        SA4 addr, cli;
        //char ip[128];
        pid_t pid;
    
        //创建socket
        s_fd = socket(AF_INET,SOCK_STREAM,0);
        if(s_fd == -1) 
        {
            perror("socket");
            return -1;
        }
    
        //初始化ipv4地址
        addr.sin_family = AF_INET;
        //初始化需要将端口号将主机字节序转换为网络字节序
        addr.sin_port = htons(g_nConnectPort);
        addr.sin_addr.s_addr = htonl(INADDR_ANY);
    
        //将s_fd和addr地址空间绑定
        int b = bind(s_fd, (SA*)&addr, sizeof(addr));
        if(b == -1) 
        {
            perror("bind");
            return -1;
        }
    
        //将s_fd设置为被动监听
        listen(s_fd, 5);//5是最多可以存放5个链接
    
        //从未决链接队列里取出一个链接
        while(1) 
        {
            int cli_len = sizeof(cli);
    
            c_fd = accept(s_fd, (SA*)&cli, &cli_len);
            if(c_fd == -1) 
            {
                perror("accept");
                return -1;
            }
    
            //printf("%s\n",inet_ntop(AF_INET,&cli.sin_addr,ip,128));
    
            //创建子进程
            pid = fork();
            if(pid == -1) 
            {
                perror("fork");
                return -1;
            }
            if(pid == 0) 
            {
                close(s_fd);
                //业务处理
                while(1)
                {
                    do_work(c_fd);
                }
    
                //关闭本次链接，结束本次通讯
                close(c_fd);
                exit(0);
            }else 
            {
                close(c_fd);
                waitpid(-1, NULL,WNOWAIT);
            }
        }
        close(s_fd);
        return 0;
    }

##### client #####

#include <stdio.h>
    #include <string.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <ctype.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <stdlib.h>
    #include <sys/wait.h>
    #include <unistd.h>
    
    typedef struct sockaddr SA;
    typedef struct sockaddr_in SA4;
    int main(int argc, char *argv[]) {
    
        SA4 serv;
        char *msg = "lao wang\n";
        char buf[128];
        int r;
        //创建一个用于通信的设备
        int s_fd = socket(AF_INET, SOCK_STREAM, 0);
        if(s_fd == -1) {
            perror("socket");
            return -1;
        }
        //初始化服务器的ip地址和端口号
        serv.sin_family = AF_INET;
        serv.sin_port = htons(15623);
        //ip地址127.0.0.1，这里的ip从终端输入
        inet_pton(AF_INET,argv[1],&serv.sin_addr);
        //将s_fd链接到服务器的地址
        int c = connect(s_fd, (SA*) &serv, sizeof(serv));
        if(c == -1) {
            perror("connect");
            return -1;
        }
        //向服务器发送消息
        write(s_fd,msg,strlen(msg));
        //阻塞等待服务器的响应消息
        r = read(s_fd, buf, 128);
        //处理响应消息
        write(1, buf, r);
        //告知服务器结束本次通话
        close(s_fd);
        return 0;
    }