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/*
* proxyarp.c - set up or clear proxyarp routing on a device.
*
* This code was taken from pppd-2.2.0e, with some revisions copied
* from pppd-2.2.0f.
*
* Copyright (c) 1989 Carnegie Mellon University.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by Carnegie Mellon University. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include "diald.h"
/* This is in netdevice.h. However, this compile will fail miserably if
you attempt to include netdevice.h because it has so many references
to __memcpy functions which it should not attempt to do. So, since I
really don't use it, but it must be defined, define it now. */
#ifndef MAX_ADDR_LEN
#define MAX_ADDR_LEN 7
#endif
#include <net/if.h>
#include <net/if_arp.h>
/* #include <net/route.h> */
#define MAX_IFS 100
#define FLAGS_GOOD (IFF_UP | IFF_BROADCAST)
#define FLAGS_MASK (IFF_UP | IFF_BROADCAST | \
IFF_POINTOPOINT | IFF_LOOPBACK | IFF_NOARP)
/*
* SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
* if it exists.
*/
#define SET_SA_FAMILY(addr, family) \
memset ((char *) &(addr), '\0', sizeof(addr)); \
addr.sa_family = (family);
/*
* Make a string representation of a network IP address.
*/
char * ip_ntoa(unsigned int ipaddr)
{
static char b[64];
ipaddr = ntohl(ipaddr);
sprintf(b, "%d.%d.%d.%d",
(u_char)(ipaddr >> 24),
(u_char)(ipaddr >> 16),
(u_char)(ipaddr >> 8),
(u_char)(ipaddr));
return b;
}
/*
* get_ether_addr - get the hardware address of an interface on the
* the same subnet as ipaddr.
*/
static int get_ether_addr (unsigned int ipaddr, struct sockaddr *hwaddr)
{
struct ifreq *ifr, *ifend;
unsigned int ina, mask;
struct ifreq ifreq;
struct ifconf ifc;
struct ifreq ifs[MAX_IFS];
ifc.ifc_len = sizeof(ifs);
ifc.ifc_req = ifs;
if (ioctl(sockfd, SIOCGIFCONF, &ifc) < 0)
{
mon_syslog(LOG_ERR, "ioctl(SIOCGIFCONF): %m");
return 0;
}
if (debug&DEBUG_PROXYARP)
mon_syslog(LOG_INFO, "proxy arp: scanning %d interfaces for IP %s",
ifc.ifc_len / sizeof(struct ifreq), ip_ntoa(ipaddr));
/*
* Scan through looking for an interface with an Internet
* address on the same subnet as `ipaddr'.
*/
ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
for (ifr = ifc.ifc_req; ifr < ifend; ifr++)
{
if (ifr->ifr_addr.sa_family == AF_INET)
{
ina = ((struct sockaddr_in *) &ifr->ifr_addr)->sin_addr.s_addr;
strncpy(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name));
if (debug&DEBUG_PROXYARP)
mon_syslog(LOG_INFO, "proxy arp: examining interface %s",
ifreq.ifr_name);
/*
* Check that the interface is up, and not point-to-point
* nor loopback.
*/
if (ioctl(sockfd, SIOCGIFFLAGS, &ifreq) < 0)
{
continue;
}
if (((ifreq.ifr_flags ^ FLAGS_GOOD) & FLAGS_MASK) != 0)
{
continue;
}
/*
* Get its netmask and check that it's on the right subnet.
*/
if (ioctl(sockfd, SIOCGIFNETMASK, &ifreq) < 0)
{
continue;
}
mask = ((struct sockaddr_in *) &ifreq.ifr_addr)->sin_addr.s_addr;
if (debug&DEBUG_PROXYARP)
mon_syslog(LOG_INFO, "proxy arp: interface addr %s mask %lx",
ip_ntoa(ina), ntohl(mask));
if (((ipaddr ^ ina) & mask) != 0)
{
continue;
}
break;
}
}
if (ifr >= ifend)
{
return 0;
}
mon_syslog(LOG_INFO, "found interface %s for proxy arp", ifreq.ifr_name);
/*
* Now get the hardware address.
*/
memset (&ifreq.ifr_hwaddr, 0, sizeof (struct sockaddr));
if (ioctl (sockfd, SIOCGIFHWADDR, &ifreq) < 0)
{
mon_syslog(LOG_ERR, "SIOCGIFHWADDR(%s): %m", ifreq.ifr_name);
return 0;
}
memcpy (hwaddr,
&ifreq.ifr_hwaddr,
sizeof (struct sockaddr));
if (debug&DEBUG_PROXYARP)
mon_syslog(LOG_DEBUG,
"proxy arp: found hwaddr %02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x",
(int) ((unsigned char *) &hwaddr->sa_data)[0],
(int) ((unsigned char *) &hwaddr->sa_data)[1],
(int) ((unsigned char *) &hwaddr->sa_data)[2],
(int) ((unsigned char *) &hwaddr->sa_data)[3],
(int) ((unsigned char *) &hwaddr->sa_data)[4],
(int) ((unsigned char *) &hwaddr->sa_data)[5],
(int) ((unsigned char *) &hwaddr->sa_data)[6],
(int) ((unsigned char *) &hwaddr->sa_data)[7]);
return 1;
}
/*
* set_proxyarp - Make a proxy ARP entry for the peer.
*/
int set_proxyarp (unsigned int his_adr)
{
struct arpreq arpreq;
memset (&arpreq, '\0', sizeof(arpreq));
/*
* Get the hardware address of an interface on the same subnet
* as our local address.
*/
if (!get_ether_addr(his_adr, &arpreq.arp_ha)) {
mon_syslog(LOG_ERR, "Cannot determine ethernet address for proxy ARP");
return 0;
}
SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
((struct sockaddr_in *) &arpreq.arp_pa)->sin_addr.s_addr = his_adr;
arpreq.arp_flags = ATF_PERM | ATF_PUBL;
if (ioctl(sockfd, SIOCSARP, (caddr_t)&arpreq) < 0) {
mon_syslog(LOG_ERR, "ioctl(SIOCSARP): %m");
return 0;
}
return 1;
}
/*
* clear_proxyarp - Delete the proxy ARP entry for the peer.
*/
int clear_proxyarp (unsigned int his_adr)
{
struct arpreq arpreq;
memset (&arpreq, '\0', sizeof(arpreq));
SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
arpreq.arp_flags = ATF_PERM | ATF_PUBL;
((struct sockaddr_in *) &arpreq.arp_pa)->sin_addr.s_addr = his_adr;
if (ioctl(sockfd, SIOCDARP, (caddr_t)&arpreq) < 0) {
mon_syslog(LOG_WARNING, "ioctl(SIOCDARP): %m");
return 0;
}
return 1;
}
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