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<div class="moz-cite-prefix">On 25/08/2021 21:09, Geoff Back wrote:<br>
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cite="mid:ac5c29ad-3c8a-2d29-d5d5-e250050adaf4@demonlair.co.uk">
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On 25/08/2021 15:33, Simon Kelley wrote:
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<pre class="moz-quote-pre" wrap="">On 25/08/2021 13:08, Geoff Back wrote:
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<pre class="moz-quote-pre" wrap="">Good morning,
TL;DR: I need to wildcard-match interface tags and can't see how.
I currently have dnsmasq working on a Linux VPN server to provide DHCP
options to VPN clients by using these config elements to bind only the
vpn interfaces:
====8<==============8<================
interface=ppp*
bind-dynamic
dhcp-range=10.99.0.254,static
dhcp-option=option:router
dhcp-option=6,10.99.0.254
dhcp-option=121,<routes>
dhcp-option=249,<routes>
====8<==============8<================
This works just fine. However, I now need to also run regular DHCP on
other interfaces with different options. Tags seem like the perfect
solution to this.
As I understand it, the interface on which the request is received
becomes a tag, which would seem fine, but as far as I can tell from the
source of version 2.85, the tag:xxx in dhcp-option etc do not support
wildcards like the 'interface' directive, so I cannot use e.g.
dhcp-option=tag:ppp*,option:router
So I figure OK, set another tag based on the interface tag to represent
a "group of interfaces", and I end up with this:
====8<==============8<================
# basic binding settings for all PPP interfaces plus two ethernets.
bind-dynamic
interface=ppp*
interface=lan2
interface=lan3
# Set a tag for all requests on PPP interfaces.
# If I understand correctly requests on ppp2 (for example) set a tag ppp2,
# This should work according to docs but there could be dozens of ppp
# interfaces in use making this really long and adding a lot of checks
to every request.
tag-if=set:ppp,tag:ppp0
tag-if=set:ppp,tag:ppp1
tag-if=set:ppp,tag:ppp2
... repeated as necessary ...
# DHCP for all ppp interfaces
# match using tag set by tag-if above.
dhcp-range=tag:ppp,10.99.0.254,static
dhcp-option=tag:ppp,option:router
dhcp-option=tag:ppp,6,10.99.0.254
dhcp-option=tag:ppp,121,<routes>
dhcp-option=tag:ppp,249,<routes>
# DHCP for lan2
# match to interface tag
dhcp-range=tag:lan2,10.0.0.1,10.0.0.99
dhcp-option=tag:lan2,option:router,10.0.0.254
====8<==============8<================
Instead of having to give large numbers of "tag-if=set:ppp,tag:ppp9"
lines for all the possible ppp interfaces, I would like to do this:
# set 'ppp' tag for all PPP interfaces
tag-if=set:ppp,tag:ppp*
Of course, allowing wildcards on all tag matches would work too, but my
thinking is that restricting wildcards to 'tag-if' avoids the
performance impact of potentially doing wildcard checks on every
'dhcp-option' etc. during DHCP packet processing and instead it gets
done once through 'tag-if'.
Have I missed something and there is already a way to do this?
Or if not, is it something that could be added?
If it's an acceptable add, I can knock up a patch to do it but I'll have
to learn enough of the dnsmasq code first.
Regards,
Geoff.
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Your solution sounds like a good one to me. I'd certainly take a patch,
especially if it updated the man page too.
To get started, look at run_tag_if() and match_netid() in
src/dhcp-common.c match_netid() does the matching and is called all over
the place, so you either need to replace the call to match_netid() in
run_tag_if() with code that implements the wildcard matching, or extend
match_netid to do wildcard matching when the third argument is 2 or
something similar.
Cheers,
Simon.
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Hi Simon,
Attached is a patch against tag v2.86rc1 that implements wildcards in
--tag-if and updates the man page.
Cheers,
Geoff.
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Hi,<br>
<br>
Oops, there's a bug in the patch (which still lets it work in my
test case). Updated patch attached.<br>
Sorry about that.<br>
<br>
Cheers,<br>
<br>
Geoff.
<pre class="moz-signature" cols="72">--
Geoff Back
What if we're all just characters in someone's nightmares?</pre>
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