getnetparam.c

使用udp的broadcast方式写的c程序

/* 
* getnetparam.c - An IP multicast server 
*/


#include <string.h> 
#include <sys/types.h> 

#include <stdio.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <netdb.h>

#include <unistd.h>

#include <stdlib.h>
 
#include <sys/ioctl.h> 
#include <net/if.h> 
#include <net/if_arp.h> 
#include <net/ethernet.h> 
#include <signal.h> 
#include <netinet/ip.h> 


#include "msgstruct.h"


nettype *getnetparam() 
{ 
	
	struct  in_addr myip, mymask; 
	int     fd_arp;              /* socket fd for receive packets */ 
	struct  ifreq   ifr;            /* ifr structure  in if.h header */ 

	char	device[32];  /* ethernet device name */ 

	struct sockaddr_in *sin_ptr; 
	u_char             *ptr; 
	int  n, i=0; 
	
	nettype *getparam;
	
	static nettype init ;
	
	getparam = (nettype *)&init;
	
	bzero(getparam, sizeof(nettype));
	
	strcpy(device, "eth0"); 
 
	if ((fd_arp = socket(AF_INET, SOCK_PACKET, htons(0x0806))) < 0) { 
		perror( "arp socket error"); 
		exit(-1); 
	} 
 
	strcpy(ifr.ifr_name, device); 
	/* ifr.ifr_addr.sa_family = AF_INET; */ 
 
	/* get ip address of my interface */ 
	if (ioctl(fd_arp, SIOCGIFADDR, &ifr) < 0) { 
		perror("ioctl SIOCGIFADDR error"); 
		exit(-1); 
	} 
	sin_ptr = (struct sockaddr_in *)&ifr.ifr_addr; 
	myip  = sin_ptr->sin_addr; 
 
	/* get network mask of my interface */ 
	if (ioctl(fd_arp, SIOCGIFNETMASK, &ifr) < 0) { 
		perror("ioctl SIOCGIFNETMASK error"); 
		exit(-1); 
	} 
	sin_ptr = (struct sockaddr_in *)&ifr.ifr_addr; 
	mymask  = sin_ptr->sin_addr; 
 
	/* get mac address of the interface */ 
	if (ioctl(fd_arp, SIOCGIFHWADDR, &ifr) < 0) {
		
		perror("ioctl SIOCGIFHWADDR error"); 
		exit(-1); 
	
	} 
	
	ptr = (u_char *)&ifr.ifr_ifru.ifru_hwaddr.sa_data[0]; 
	
	/*
	printf( "request mac %02x:%02x:%02x:%02x:%02x:%02x\n",  
            *ptr, *(ptr + 1), *(ptr + 2), *(ptr + 3),  
            *(ptr + 4), *(ptr + 5) ); 
	printf( "request netmask  %s\n", inet_ntoa(mymask)); 
	printf( "request IP  %s\n", inet_ntoa(myip));
	
	*/
 	
 	
	for(i=0;i<6;i++) {
 		
		getparam->mac_value[i] = *(ptr+i);
 	
	}
 
	getparam->mac_value[i] = 0;
	sprintf( getparam->ip_value, "%s", inet_ntoa(myip));
  	
	sprintf( getparam->netmask_value, "%s", inet_ntoa(mymask));
  	
	strcpy(getparam->message, CONST_MESSAGE);
  
	strcpy(getparam->dev_type,DEVICE_TYPE);
	getparam->msg_type = NETPARAM; 
	getparam->reserve[0] = DEVICE_CHANNEL;
	close(fd_arp);
  	
	return getparam;
  	
}  /* end of main */