On 25/08/2021 13:08, Geoff Back wrote: > 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. >
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. _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss
