listener.c

老师上课演示的在Linux上运行的网络聊天小程序,很有启发.

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

#define MYPORT 4950  //端口号
#define MAXBUFLEN 100  //接收消息的最大长度

main()
{
	int sockfd;
	struct sockaddr_in my_addr;
	struct sockaddr_in their_addr;
	int addr_len,numbytes;
	char buf[MAXBUFLEN];
 /*创建一个socket,赋值给sockfd,创建成功则继续,否则输出出错信息并结束运行*/
	if ((sockfd=socket(AF_INET,SOCK_DGRAM,0))==-1)
	{
		perror("socket");
		exit(1);
	}
	my_addr.sin_family=AF_INET;  //设定地址簇类型
	my_addr.sin_port=htons(MYPORT);  //给端口赋值
	my_addr.sin_addr.s_addr=INADDR_ANY;  //用连接地址进行自动填充IP
	bzero(&(my_addr.sin_zero),8);
 /*将IP地址和端口信息绑定到前面创建的socket上,绑定成功则继续,否则输出出错信息并结束运行*/
	if (bind(sockfd,(struct sockaddr *)&my_addr,sizeof(struct sockaddr))==-1)
	{
		perror("bind");
		exit(1);
	}
	addr_len=sizeof(struct sockaddr);
 /*接收消息,存放到buf中,their_addr中存放对方的IP地址信息*/
　　if((numbytes=recvfrom(sockfd,buf,MAXBUFLEN,0,(struct sockaddr*)&their_addr,&addr_len))==-1)
	{
		perror("recvfrom");
		exit(1);
	}
	printf("got packet from %s\n",inet_ntoa(their_addr.sin_addr));
	printf("packet is %d bytes long\n",numbytes);
	buf[numbytes]='\0';
	printf("packet contains \"%s\"\n",buf);
	close(sockfd);  //关闭socket
}