Bug Report from www.isc.org:

Name: Paul B. Henson
Email: henson@cpp.edu
Software Version: 4.3.3P1
OS: Gentoo Linux
Subject:V6 - dhcpd: Unable to pick client address: no addresses available


Bug Detail
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In a /64 pool with only 5577 addresses allocated, the server says no addresses are available:

dhcpd: Unable to pick client address: no addresses available  - shared
network 2620:df:8000:4701::/64: 4294967296 total, 5577 active,  0 abandoned

It seems with over 4 *billion* to choose from one could be found 8-/. It looks like this issue comes from:

https://github.com/mpalmer/isc-dhcp/blob/6a90108410e9dcf22e458ca950b055e1ece3761
8/server/mdb6.c#L931-L1080                                                      

where it arbitrarily hashes the DUID only 100 times looking for an address to give out before giving up. The comment at the top says "Realistically this will only happen in very full pools", I hereby introduce the author to the difference between statistics and real life ;).

It seems when there are 4 billion free addresses this function should not throw up its hands and give a "no addresses available" error :(.

Thanks...

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