Linux网络编程

//tcpserver.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <sys/wait.h>
#define PORT 4008
#define BACKLOG 10
#define BUFSIZE 4096
void process(char * cmd);
int main(int argc,char* argv[])
{
    int lsockfd,rsockfd;
    struct sockaddr_in lsocket,rsocket;
    if((lsockfd=socket(AF_INET,SOCK_STREAM,0))<0)   //服务器端套接字
    {
        perror("socket");   
        exit(1);  
    }  
    
    lsocket.sin_family=AF_INET;  //设置服务器端地址
    lsocket.sin_port=htons(PORT);
    lsocket.sin_addr.s_addr=INADDR_ANY;
    bzero(&(lsocket.sin_zero),8);

    if(bind(lsockfd,(struct sockaddr *)&lsocket,sizeof(struct sockaddr))<0)  //将服务器端地址与套接字绑定
    {
        perror("bind");
        exit(1);
    }

    if(listen(lsockfd,BACKLOG)<0)    //监听服务器端套接字，若有客户端connect，则将其加入监听队列
    {
        perror("listen");
        exit(1);
    }

    int sin_size=sizeof(struct sockaddr);
    int count=0;
    while(1)
    {
        printf("wait for connecting!\n");
        if((rsockfd=accept(lsockfd,(struct sockaddr *)&rsocket,&sin_size))<0)  //处理客户端请求
        {
            perror("accept");
            continue;
        }
        count++;
        printf("someone connect!,current people %d\n",count);

        if(!fork())                            //为么一个客户端建立一个处理子进程，用来收发数据
        {
            char str[BUFSIZE];
            int numbytes=0;
            while(1)
            {
            if((numbytes=recv(rsockfd,str,BUFSIZE-1,0))<0)
            {
                perror("recv");
                break;
            }
            str[numbytes]=‘\0‘;
            if(strcmp(str,"quit")==0)
            {
                printf("client quit!\n");
                break;
            }
            
            printf("receive a message: %s\n",str);
            if(send(rsockfd,str,strlen(str),0)<0)
            {
                perror("send");
                break;
            }
            }
            close(rsockfd);
            exit(0);
            
        }
        while(waitpid(-1,NULL,WNOHANG)>0) //此处不会阻塞若第三个参数为WUNTRACED则会阻塞，若有客户端子进程退出，则输出相关语句
        {
            count--;
            printf("someone quit!,current people have %d\n",count);
        }   
        
    }   
    return 0;
}

//tcpclient.c gcc tcpclient.c -o tcpclient  运行tcpclient 127.0.0.1 //输入quit退出
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define PORT 4008
#define MAXDATASIZE 4096
#define BUFSIZE 4096
int main(int argc,char *argv[])
{
    int rsockfd;
    struct sockaddr_in rsocket;
    if(argc!=2)
    {
        fprintf(stderr,"usage:client hostname\n");
        exit(1);
    }   

    if((rsockfd=socket(AF_INET,SOCK_STREAM,0))<0)  //创建一个服务器端套接字
    {
        perror("sock");
        exit(1);
    }

    rsocket.sin_family=AF_INET;       //设置服务器端地址
    rsocket.sin_port=htons(PORT);
    rsocket.sin_addr.s_addr=inet_addr(argv[1]);
    // if(inet_pton(AF_INET,argv[1],&rsocket.sin_addr)<0)
    // {
    //     perror("inet_pton");
    //     exit(1);
    // }
   // rsocket.sin_addr=*(struct in_addr*)he->h_addr;
    bzero(&(rsocket.sin_zero),8);
    
    if(connect(rsockfd,(struct sockaddr*)&rsocket,sizeof(struct sockaddr))<0)  //连接服务器
    {
        perror("connect");
        exit(1);
    }
    char sstr[BUFSIZE];
    char rstr[BUFSIZE];
    while(1)                //收发数据，输入quit退出
    {           
        printf("%15s","command is: ");
        int len=0;
        fgets(sstr,BUFSIZE,stdin);
        sstr[strlen(sstr)-1]=0;
        if(send(rsockfd,sstr,strlen(sstr),0)<0)   
        {
            perror("send");
            continue;
        }
        if(strcmp(sstr,"quit")==0)
        break;
        int numbytes=0;
        if((numbytes=recv(rsockfd,rstr,BUFSIZE-1,0))<0)
        {
            perror("recv");
            continue;
        }
        rstr[numbytes]=‘\0‘;
        printf("%15s%s\n","result is: ",rstr); 
    }
    close(rsockfd);
    return 0;
}