- /* Check if this is a valid ARP request */
-
- if(ntohs(arp->arp_hrd) != ARPHRD_ETHER ||
- ntohs(arp->arp_pro) != ETHERTYPE_IP ||
- (int) (arp->arp_hln) != ETHER_ADDR_LEN ||
- (int) (arp->arp_pln) != 4 ||
- ntohs(arp->arp_op) != ARPOP_REQUEST )
- {
- if(debug_lvl > DEBUG_TRAFFIC)
- {
- syslog(LOG_WARNING, _("Cannot route packet: received unknown type ARP request"));
- }
- return;
- }
-
- /* Check if the IP address exists on the VPN */
-
- subnet = lookup_subnet_ipv4((ipv4_t *)arp->arp_tpa);
-
- if(!subnet)
- {
- if(debug_lvl >= DEBUG_TRAFFIC)
- {
- syslog(LOG_WARNING, _("Cannot route packet: ARP request for unknown address %d.%d.%d.%d"),
- arp->arp_tpa[0], arp->arp_tpa[1], arp->arp_tpa[2], arp->arp_tpa[3]);
- }
-
- return;
- }
-
- /* Check if it is for our own subnet */
-
- if(subnet->owner == myself)
- return; /* silently ignore */
-
- memcpy(packet->data, packet->data + ETHER_ADDR_LEN, ETHER_ADDR_LEN); /* copy destination address */
- packet->data[ETHER_ADDR_LEN*2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
-
- memcpy(ipbuf, arp->arp_tpa, 4); /* save protocol addr */
- memcpy(arp->arp_tpa, arp->arp_spa, 4); /* swap destination and source protocol address */
- memcpy(arp->arp_spa, ipbuf, 4); /* ... */
-
- memcpy(arp->arp_tha, arp->arp_sha, 10); /* set target hard/proto addr */
- memcpy(arp->arp_sha, packet->data + ETHER_ADDR_LEN, ETHER_ADDR_LEN); /* add fake source hard addr */
- arp->arp_op = htons(ARPOP_REPLY);
-
- write_packet(packet);
-cp
-}