[Dnsmasq-discuss] [PATCH] Offered IPv4 DHCP address ping fix

[Petr Menšík]

Hi Simon and others,

I am debugging strange issue, which happens inside OpenStack in certain
situations. It seems under not precisely defined conditions dnsmasq
returns "no address available" error even in situation, when not yet all
leases are used.

It seems do_icmp_ping is responsible for ruling out recently tried IP
addresses. It seems a bit weird address allocation happens only for
addresses recently not pinged. I have found another place which does
do_icmp_ping, but does not use hash value computed from hardware
address. Even when it is already known at that time. First patch
attached adds hash also to second place. That should mean single address
would use shared ping. The second patch simplifies a bit do_icmp_patch
and its return value. Instead of artificially ensuring hash would match,
just return correct value when hash matches. The second change is just
optional optimization.

Few details are at RH bug #2028704 [1]. Original tested version 2.79 did
not contain commit 0669ee7a69a
<http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=0669ee7a69a004ce34fed41e50aa575f8e04427b>
[2], which improves the situation. But I think there remain cases when
ping is not accepted when it should be. Testing with latest release did
not work according to report. I think the first patch may fix still
missing part.

Cheers,
Petr

1. https://bugzilla.redhat.com/show_bug.cgi?id=2028704
2.
http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=0669ee7a69a004ce34fed41e50aa575f8e04427b

-- 
Petr Menšík
Software Engineer
Red Hat, http://www.redhat.com/
email: pemensik at redhat.com
PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB
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