if.c

linux下远程启动服务/bootp服务器源代码

/*
 *
 *   bootpd_nis: simple BOOTP server with NIS maps support
 *   Copyright (C) 2005 <[e-mail]>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *
 *  $Id: if.c,v 1.2 2005/03/02 20:57:24 bfleisch Exp $
 *
 */




#include "if.h"


#define NETWORK_ADDR(addr, netmask) ( ((in_addr_t)(addr.s_addr)) & ((in_addr_t)(netmask.s_addr)))
#define ON_SAME_NETWORK(addr1, addr2, netmask)  ( (NETWORK_ADDR((addr1), (netmask)) == NETWORK_ADDR((addr2),(netmask))))



#define MAX_NETWORK_INTERFACES 20
static struct ifreq ireqs[MAX_NETWORK_INTERFACES];


/*
 * lookup which network interface matches to given IP address
 *
 * WARNING: static structure returned.
 */


struct ifreq*
get_if_by_addr(const struct in_addr *addr)
{
  struct ifconf iconf;
  struct ifreq *ireq;

  int fd;
  int pos;
  int idx;
   struct in_addr if_addr;
  struct in_addr if_netmask;
  
  iconf.ifc_len = sizeof (ireqs);
  iconf.ifc_req = ireqs;
  
  fd = socket(AF_INET, SOCK_DGRAM, 0);
  if (fd < 0)
    return NULL; 
    
  if (ioctl(fd, SIOCGIFCONF, &iconf) <0)
  {
    perror("ioctl(SIOCGIFCONF)");
    close(fd);
    return NULL;
  }
  

  pos=0;
  idx=0;
  while (pos < iconf.ifc_len)
  {
    ireq = &iconf.ifc_req[idx];
    pos += sizeof(struct ifreq);
    idx++;
    
    if ( ireq->ifr_addr.sa_family != AF_INET)
      continue;
      
    memcpy ( &if_addr, &((struct sockaddr_in*)&ireq->ifr_addr)->sin_addr, sizeof(struct in_addr));

    if (ioctl(fd, SIOCGIFNETMASK , ireq) !=0)
    {
      perror("ioctl(SIOCGIFNETMASK)");
      continue;
    }
           
    memcpy ( &if_netmask, &((struct sockaddr_in*)&ireq->ifr_addr)->sin_addr, sizeof(struct in_addr));          

    if (ON_SAME_NETWORK(if_addr, *addr, if_netmask)) 
    {
      close(fd);
      return ireq;
    }
  }

  close(fd);
  return NULL;    /* no match */
}


/*
 * return interface information in if_info strucutre
 *
 * Warning: static structure returned 
 */

struct if_info*
get_if_info(const char* if_name)
{

  static struct if_info if_info;
  struct ifconf iconf;
  struct ifreq* ireq;
  int ifs;
  char iconf_buf[8192];
  int n;
  struct sockaddr_in *addr;
  
  memset(&if_info, 0, sizeof( struct if_info));

  ifs = socket(PF_INET, SOCK_STREAM, 0);

  if (ifs <=0)
  {
    log_perror(LOG_NOTICE, "socket()");
    return NULL;
  }

  iconf.ifc_len = sizeof (iconf_buf);
  iconf.ifc_buf = iconf_buf;

  if (ioctl( ifs, SIOCGIFCONF, &iconf) != 0)
  {
    log_perror(LOG_NOTICE, "ioctl(SIOCGIFCONF)");
    exit (1); 
  }

  n=0;

  do
  {
   ireq= (struct ifreq*) (iconf.ifc_buf + n);  
   n += sizeof (struct ifreq);

   addr = (struct sockaddr_in*) &ireq->ifr_addr;


   if (addr->sin_family != AF_INET) 
     continue;
   if ( strcmp(ireq->ifr_name, if_name)!=0)
     continue;


  /*
   * interface address 
   */

  memcpy(&(if_info.if_addr), &(addr->sin_addr), sizeof(struct in_addr));


  /*
   * interface netmask
   */

  if (ioctl (ifs, SIOCGIFNETMASK, ireq) !=0)
       log_perror(LOG_NOTICE, "ioctl(SIOCGIFFLAGS)");
  else        
  {
     addr = (struct sockaddr_in*) &ireq->ifr_addr;
     memcpy(&(if_info.if_netmask), &(addr->sin_addr), sizeof(struct in_addr));
  }
  
  /*
   * interface broadcast address
   */

  if (ioctl (ifs, SIOCGIFBRDADDR, ireq) !=0)
     log_perror(LOG_NOTICE, "ioctl(SIOCGIFBRDADDR)");
   else        
   {
     addr = (struct sockaddr_in*) &ireq->ifr_addr;
     memcpy(&(if_info.if_broadcast), &(addr->sin_addr), sizeof(struct in_addr));
   }

  n=0;
  break;

  } while (n< iconf.ifc_len); 
  close(ifs);
  
  return (n == 0) ? &if_info : NULL;
}