c语言网络编程聊天系统_用户程序在用户态下使用系统调用

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

#define PORT 6666   //端口号
#define SIZE 1024   //定义的数组大小

int create_socket()    //创建套接字和初始化以及监听函数
{
        int listen_socket = socket(AF_INET, SOCK_STREAM, 0);
        //创建一个负责监听的套接字 协议族，协议类型，具体协议，返回大于0表示创>建成功
        if(listen_socket< 0)
        {
                perror("socket");
                return -1;
        }
        struct sockaddr_in addr;
        memset(&addr, 0, sizeof(addr));
        //服务器端地址结构
        addr.sin_family = AF_INET;  /* Internet地址族 */
        addr.sin_port = htons(PORT);  /* 端口号 */
        addr.sin_addr.s_addr = htonl(INADDR_ANY);   /* 服务器IP地址 */

        if(bind(listen_socket, (struct sockaddr *)&addr, sizeof(addr))==-1){
                perror("bind");
                return -1;
        }

        if(listen(listen_socket, 4) == -1)  //监听
        {
                perror("listen");
                return -1;
        }
        return listen_socket;
}

//信息处理函数,功能是将客户端传过来的小写字母转化为大写字母
void *handle_client(void *ptr){
        int fd=*(int *)ptr;
          
        printf("the new connect_socket is %d\n",fd);
        char buf[SIZE];
        while(1)
        {
                int ret = read(fd, buf, SIZE-1);
                if(ret == -1)
                {
                        perror("read");
                        break;
                }
                if(ret == 0)
                        break;
                buf[ret] = '\0'；             
                printf("%s\n", buf);
                write(fd, buf, ret);
        if(strncmp(buf,"bye",3)==0)
            break;    
        }
        close(fd);
        printf("连接已断开\n");
}

int main()
{
        pthread_t thread;
        int listen_socket = create_socket();

        struct  sockaddr_in client_addr;
        socklen_t addrlen=sizeof(client_addr);
        printf("等待与客户端连接......\n");
        while(1){
        int client_socket=accept(listen_socket,(struct sockaddr *)&client_addr,&addrlen);
        if(client_socket==-1){
               　　 perror("accept error\n");
               　　 return -1;
        }  
        printf("connect success %s\n",inet_ntoa(client_addr.sin_addr));
        pthread_create(&thread,NULL,handle_client,(void *)&client_socket);

        }
        printf("close socket");
        close(listen_socket);
        return 0;
}

#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<unistd.h>
#include<stdlib.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#define s 512
int main(int argc,const char* argv[])
{
    
    if(argc != 3)
    {
        printf("Usage:%s [ip] [port]\n",argv[0]);
        return 0;
    }

    //创建一个用来通讯的socket
    int sock = socket(AF_INET,SOCK_STREAM, 0);
    if(sock < 0)
    {
        perror("socket");
        return 1;
    }

    //服务器端的地址结构体
    struct sockaddr_in server;
    server.sin_family = AF_INET;
    server.sin_port = htons(atoi(argv[2]));
    //inet_addr 将字符串格式的ip地址转化为网络字节顺序
    server.sin_addr.s_addr = inet_addr(argv[1]);
    socklen_t len = sizeof(struct sockaddr_in);
    if(connect(sock, (struct sockaddr*)&server, len) < 0 )
    {
        perror("connect");
        return 2;
    }
    //连接成功进行发送和接受数据
    char buf[1024];
    char buf_rec[1024];
    while(1)
    {
        printf("send:");
        fflush(stdout); 
        ssize_t _s = read(0, buf, sizeof(buf)-1);
        buf[_s] = 0;
        write(sock, buf, _s);
   　　 if(strncmp(buf,"bye",3)==0)
       　　 break;    
   　　 recv(sock,buf_rec,s,0);
   　　 printf("%s\n",buf_rec);   
    }
    close(sock);
    printf("client close socket");
    return 0;
}