功能实现

实现客户端向服务端传输字符串，服务端打印服务端的ip和端口号并将字符串逆序回传给客户端。

测试环境：

Linux 服务器 （或者搭建本地虚拟机两台，处于同一网段）
也可以通过环回接口模拟服务端和客户端通信。

功能测试

服务端代码

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

#define SERVER_PORT 888

void reverse(char* arr,int begin,int end)
{
	if(begin >= end)	return;
	while(begin < end)
	{
		char tmp = arr[begin];
		arr[begin] = arr[end];
		arr[end] = tmp;
		begin++,end--;
	} 
		
}

int main()
{
	int sock = socket(AF_INET,SOCK_STREAM,0);
	struct sockaddr_in server_addr;
	
	memset(&server_addr,0,sizeof(server_addr));
	server_addr.sin_family = AF_INET;	//指定协议族
	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//监听本地所有ip
	server_addr.sin_port = htons(SERVER_PORT);//绑定端口号
	
	//
	bind(sock,(struct sockaddr*)&server_addr,sizeof(server_addr));
	
	listen(sock,128);
	
	printf("等待用户连接：\n");
	
	while(1)
	{
		struct sockaddr_in client;
		int client_sock;
		socklen_t client_len = sizeof(client);
		char client_ip[33];
		
	//	memset(&client,0,sizeof(client));
	//	memset(&server_addr,0,sizeof(server_addr));
		
		client_sock = accept(sock,(struct sockaddr*)&client,&client_len);
		
		
		printf("client ip :%s\n",inet_ntop(AF_INET,&client.sin_addr.s_addr,client_ip,sizeof(client_ip)));
		printf("client port :%d\n",ntohs(client.sin_port));
	
		char buf[256];
		int len = read(client_sock,buf,sizeof(buf) - 1);
		buf[len] = 0;
		printf("%s\n",buf);	
		
		reverse(buf,0,len-1);
		len =  write(client_sock,buf,len);		

		
		close(client_sock);
	}
	
	
}

客户端代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define SERVER_PORT 888
#define SERVER_IP  "192.168.23.202"

int main(int argc, char *argv[]){

    int sockfd;
    char *message;
    struct sockaddr_in servaddr;
    int n;
    char buf[64];

    if(argc != 2){
        fputs("input error\n", stderr);
        exit(1);
    }

    message = argv[1];

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    memset(&servaddr, '\0', sizeof(struct sockaddr_in));
    servaddr.sin_family = AF_INET;
    inet_pton(AF_INET, SERVER_IP, &servaddr.sin_addr);
    servaddr.sin_port = htons(SERVER_PORT);

    connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

    write(sockfd, message, strlen(message));

    n = read(sockfd, buf, sizeof(buf)-1);

    if(n > 0){
        buf[n]='\0';
        printf("receive: %s\n", buf);
    }else {
        perror("error!!!");
    }

    printf("finished.\n");
    close(sockfd);

    return 0;
}