linux网络编程——客户端编程

$\qquad$ 一个简单的客户端/服务端通信程序。
$\qquad$ 服务端：将客户端上传的字符串，改为大写字符串，并且显示客户端的IP和端口号。

#include<stdio.h>
#include<unistd.h>
#include<sys/socket.h>
#include<stdlib.h>
#include<ctype.h>
#include<arpa/inet.h>#define SERV_PORT 6666
int main()
{int lfd,cfd;struct sockaddr_in serv_addr,clie_addr;socklen_t clie_addr_len,clie_IP_len;char buf[BUFSIZ],clie_IP[BUFSIZ];int n,ret;lfd = socket(AF_INET,SOCK_STREAM,0);if(lfd==-1){perror("socket error");exit(1);}serv_addr.sin_family = AF_INET;serv_addr.sin_port = htons(SERV_PORT);serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);ret = bind(lfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr));if(ret==-1){perror("bind error");exit(1);}   ret = listen(lfd,128);if(ret==-1){perror("listen error");exit(1);}clie_addr_len = sizeof(clie_addr);cfd = accept(lfd,(struct sockaddr *)&clie_addr,&clie_addr_len);if(cfd==-1){perror("accept error");exit(1);}printf("client IP:%s,client port:%d\n",inet_ntop(AF_INET,&clie_addr.sin_addr.s_addr,clie_IP,sizeof(clie_IP)),ntohs(clie_addr.sin_port));while(1){n = read(cfd,buf,sizeof(buf));for(int i=0;i<n;i++){buf[i] = toupper(buf[i]);}write(cfd,buf,n);}close(lfd);close(cfd);return 0;
}

$\qquad$ 客户端：将字符串上传到服务端

#include <stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<arpa/inet.h> 
#include<string.h>
#define SERV_IP "192.168.0.2"
#define SERV_PORT 6666
int main()
{int cfd;struct sockaddr_in serv_addr;socklen_t serv_addr_len;char buf[BUFSIZ];int n;cfd = socket(AF_INET,SOCK_STREAM,0);memset(&serv_addr,0,sizeof(serv_addr)); serv_addr.sin_family = AF_INET;serv_addr.sin_port = htons(SERV_PORT);inet_pton(AF_INET,SERV_IP,&serv_addr.sin_addr.s_addr);connect(cfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr));while(1){fgets(buf,sizeof(buf),stdin);write(cfd,buf,strlen(buf));n = read(cfd,buf,sizeof(buf));write(STDOUT_FILENO,buf,n);}   close(cfd);return 0;
}