简单的，使用套接字实UDP通信（循环服务器）

最新推荐文章于 2024-07-17 23:57:22 发布

原创最新推荐文章于 2024-07-17 23:57:22 发布 · 949 阅读

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本文介绍了一个简单的UDP通信案例，包括服务器端和客户端的实现。服务器监听8000端口，接收客户端消息并转换为大写返回。客户端向指定IP地址的8000端口发送消息，并接收服务器响应。

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/*udp_server.c*/

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

#define N 100

int main()
{
	int sockfd;
	struct sockaddr_in servaddr;
	struct sockaddr_in cliaddr;
	socklen_t clilen;
	char msg[N];
	int ret;
	int i;
	int n;
	int opt = 1;


	sockfd = socket(AF_INET,SOCK_DGRAM,0);
	if(sockfd == -1)
	{
		printf("socket errpor!\n");
		exit(-1);
	}

	ret = setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));
	if(ret == -1)
	{
		printf("setsockopt error!\n");
		exit(-1);
	}

	bzero(&servaddr,sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(8000);

	ret = bind(sockfd,(struct sockaddr *)&servaddr,sizeof(servaddr));
	if(ret == -1)
	{
		printf("bind error!\n");
		exit(-1);
	}

	clilen = sizeof(cliaddr);

	while(1)
	{
		n = recvfrom(sockfd,msg,N,0,(struct sockaddr*)&cliaddr,&clilen);
		if(n == 0)
		{
			printf("client is closed!\n");
			break;
		}
		msg[n] = '\0';
		printf("recv:%s",msg);
		for(i = 0; i < n; i++)
		{
			if(msg[i] >= 'a' && msg[i] <= 'z')
			{
				msg[i] -= 32;
			}
		}		
		printf("send:%s",msg);
		sendto(sockfd,msg,n,0,(struct sockaddr*)&cliaddr,sizeof(cliaddr));
	}

	close(sockfd);

    return 0;
}

/*udp_client.c*/

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

#define N 100

int main(int argc,char **argv)
{
	int sockfd;
	struct sockaddr_in servaddr;
	char sendbuf[N];
	char recvbuf[N];
	int n;
	int ret;

	if(argc != 2)
	{
		printf("usage:server <ip address>\n");
		exit(-1);
	}
	sockfd = socket(AF_INET,SOCK_DGRAM,0);
	if(sockfd == -1)
	{
		printf("socket error!\n");
		exit(-1);
	}

	bzero(&servaddr,sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = inet_addr(argv[1]);
	servaddr.sin_port = htons(8000);


	while(fgets(sendbuf,N,stdin) != 0)
	{
		sendto(sockfd,sendbuf,strlen(sendbuf),0,(struct sockaddr *)&servaddr,sizeof(servaddr));
		n = recvfrom(sockfd,recvbuf,N,0,NULL,NULL);
		recvbuf[n] = '\0';
		printf("recv:%s",recvbuf);
	}

	close(sockfd);
    return 0;
}