listen.c

使用udp的broadcast方式写的c程序

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

#include "msgstruct.h"
#include "broadcast.h"
int main()
{ 
	struct ip_mreq command; 
	int loop = 1;
	
	/* 多播循环 */ 
	int iter = 0;
	int sin_len;
	int socket_descriptor;
	struct sockaddr_in sin;
	struct hostent *server_host_name, serverhost;

	int recvcnt;
	broadcasttype *recvmsg;
	nettype *localnetparam;
	server_host_name = (struct hostent *)&serverhost;	
	recvmsg = (broadcasttype *)malloc(sizeof(broadcasttype)) ;


	localnetparam = (nettype *)malloc(sizeof(nettype)) ;
	
	/*get localhost ip/mac/netmask*/
	localnetparam = getnetparam();
	
	if((server_host_name = gethostbyname(HOST_NAME)) == 0) {
		perror("gethostbyname");
		exit(EXIT_FAILURE);
	}

	/*bzero(&sin, sizeof(sin));*/
	memset(&sin, 0, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_addr.s_addr = htonl(INADDR_ANY);
	sin.sin_port = htons(BROADCAST_PORT);

	if((socket_descriptor = socket(PF_INET, SOCK_DGRAM, 0)) == -1) { 
		perror("socket");
		exit(EXIT_FAILURE);
	}
	
	/* 调用bind之前，设置套接口选项启用多播IP支持*/
	loop = 1;
	if(setsockopt(socket_descriptor,SOL_SOCKET, SO_REUSEADDR,&loop, sizeof(loop)) < 0) { 
		perror("setsockopt:SO_REUSEADDR");
		exit(EXIT_FAILURE);
	}
	if(bind(socket_descriptor,(struct sockaddr *)&sin, sizeof(sin)) < 0) {
		perror("bind"); 
		exit(EXIT_FAILURE);
	}
	
	/* 在同一个主机上进行广播设置套接口，
		作用是方便单个开发系统上测试多播IP广播 */ 
	loop = 1; 
	if(setsockopt(socket_descriptor,IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)) < 0) {
		perror("setsockopt:IP_MULTICAST_LOOP");
		exit(EXIT_FAILURE); 
	} 
	
	/* 加入一个广播组。进一步告诉Linux内核，
		特定的套接口即将接受广播数据*/ 
	command.imr_multiaddr.s_addr = inet_addr(HOST_NAME); 
	command.imr_interface.s_addr = htonl(INADDR_ANY);
	if(command.imr_multiaddr.s_addr == -1) {  
		perror("224.0.0.1 not a legal multicast address"); 
		exit(EXIT_FAILURE); 
	}
	
	if (setsockopt(socket_descriptor, IPPROTO_IP, IP_ADD_MEMBERSHIP,&command, sizeof(command)) < 0) {   
		perror("setsockopt:IP_ADD_MEMBERSHIP");
	}
	while(1) {    
		sin_len = sizeof(sin); 
		recvcnt=recvfrom(socket_descriptor, recvmsg, sizeof(broadcasttype), 0,(struct sockaddr_in *)&sin, &sin_len);
		if(recvcnt == -1) {
			perror("recvfrom");
		}
		iter++;
		printf("send: %d\n", iter);
		printf("Message=%s\n", recvmsg->message);
		printf("IP=%s\n", recvmsg->ipaddress);
		
		if(!strcmp(CONST_MESSAGE, recvmsg->message) && (recvmsg->msg_type == BROADPARAM)) {
		
			/*send localnetparam to recvmsg->ipaddress when receive broadcast*/
			udp_send_ip(recvmsg->ipaddress, localnetparam,sin.sin_port);
		}

		usleep(10*1000);
	} 
	
	/* 接受广播后退出 */ 
	if(setsockopt(socket_descriptor, IPPROTO_IP, IP_DROP_MEMBERSHIP,&command, sizeof(command)) < 0) { 
		perror("setsockopt:IP_DROP_MEMBERSHIP"); 
	}
	
	free(localnetparam);
	free(recvmsg);
	
	close(socket_descriptor); 
	exit(0);
}