[Dnsmasq-discuss] Improve DHCP stateless support

Vladislav Grishenko themiron at mail.ru
Sun Oct 14 12:14:43 BST 2012


Hi Simon,

As I wrote bofore, it's impossible to setup dnsmasq to do only DHCPv6
stateless and to not depend on interface/config addresses/prefixes.
DHCPv6 stateless mode should not care about address allocation, but dnsmasq
code enforces it with ra-stateless and even static.
Suggested patch allows to setup DHCPv6 static range up to ::/0, what means
every and any client will be served with stateless options like DNS, etc.

Following example enables DHCPv6 stateless information allocation for any
requesting client (after interface/address filtering, if set), including
DNSv6 derived from current interface address, DNSv6 search list and
information-refresh time to prevent obsolete data usage on clients for the
default time value (86400).
Clients get autonomous prefixes and default route via RA (radvd) with O bit
(AdvOtherConfigFlag) set.
No dnsmasq restart is needed in case of prefixes and listening interface
address changes.

dhcp-range=::,::,static,0
dhcp-option=option6:23,[::]
dhcp-option=option6:24,example.com
dhcp-option=option6:32,600

Known bug: information-request messages handling lacks of full tag support,
including ra-stateless, static ranges.
Only interface name and DHCPv6 tag will be added, whatever they were set for
range. DNSv6 option will be used in any case (if set), but any others with
tags - will not.
Fixing it is highly useful, but is out of the subject scope.
Test case:

dhcp-range=set:lan,::,::,static,0
dhcp-option=tag:lan,option6:23,[::]
dhcp-option=tag:lan,option6:24,example.com
dhcp-option=tag:lan,option6:32,600

Refer patch attached.

Best Regards, Vladislav Grishenko
ICQ: 303357
MSN: themiron at mail.ru
Skype: the.miron

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