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arp: Don't answer announcements from guest or namespace

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Depending on the configuration, the host might have the same address.
Don't answer them to avoid a duplicate IP address detection.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2021-08-19 19:44:31 +02:00
parent 1e49d194d0
commit 2166c5872e
1 changed files with 6 additions and 0 deletions
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6
arp.c
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@ -57,6 +57,12 @@ int arp(struct ctx *c, struct ethhdr *eh, size_t len)
ah->ar_op != htons(ARPOP_REQUEST)) ah->ar_op != htons(ARPOP_REQUEST))
return 1; return 1;
/* Discard announcements (but not 0.0.0.0 "probes"): we might have the
* same IP address, hide that.
*/
if (*((uint32_t *)&am->sip) && !memcmp(am->sip, am->tip, 4))
return 1;
ah->ar_op = htons(ARPOP_REPLY); ah->ar_op = htons(ARPOP_REPLY);
memcpy(am->tha, am->sha, ETH_ALEN); memcpy(am->tha, am->sha, ETH_ALEN);
memcpy(am->sha, c->mac, ETH_ALEN); memcpy(am->sha, c->mac, ETH_ALEN);