diff options
| author | Joe Hershberger <joe.hershberger@ni.com> | 2013-02-08 14:18:53 -0600 |
|---|---|---|
| committer | Joe Hershberger <joe.hershberger@ni.com> | 2013-06-24 19:11:13 -0500 |
| commit | 5da7cf81c8d76c7b5ddf5225224141eae4e706be (patch) | |
| tree | 0ea9ad8019a3840aef63ed0727e0b72413a44463 /net/link_local.c | |
| parent | 62d7dba7be212f9834d4aa8f1920f484dec0075c (diff) | |
net: Correct check for link-local target IP conflict
Make the link-local code conform more completely with the RFC.
This will prevent ARP queries for the target (such as while it is
rebooting) from causing the device to choose a different link-local
address, thinking that its address is in use by another machine.
Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Diffstat (limited to 'net/link_local.c')
| -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 1ba796ebdf..4152fae5ba 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; } |