diff options
| -rw-r--r-- | net/link_local.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/net/link_local.c b/net/link_local.c index 1ba796e..4152fae 100644 --- a/net/link_local.c +++ b/net/link_local.c @@ -206,6 +206,7 @@ void link_local_receive_arp(struct arp_hdr *arp, int len) { int source_ip_conflict; int target_ip_conflict; + IPaddr_t null_ip = 0; if (state == DISABLED) return; @@ -267,10 +268,18 @@ void link_local_receive_arp(struct arp_hdr *arp, int len) ) { source_ip_conflict = 1; } - if (arp->ar_op == htons(ARPOP_REQUEST) - && memcmp(&arp->ar_tpa, &ip, ARP_PLEN) == 0 - && memcmp(&arp->ar_tha, NetOurEther, ARP_HLEN) != 0 - ) { + + /* + * According to RFC 3927, section 2.2.1: + * Check if packet is an ARP probe by checking for a null source IP + * then check that target IP is equal to ours and source hw addr + * is not equal to ours. This condition should cause a conflict only + * during probe. + */ + if (arp->ar_op == htons(ARPOP_REQUEST) && + memcmp(&arp->ar_spa, &null_ip, ARP_PLEN) == 0 && + memcmp(&arp->ar_tpa, &ip, ARP_PLEN) == 0 && + memcmp(&arp->ar_sha, NetOurEther, ARP_HLEN) != 0) { target_ip_conflict = 1; } |