[Dnsmasq-discuss] Config Parcing Bug

Tasnad Kernetzky tasnadk at gmail.com
Sat Jan 12 00:22:47 GMT 2019


Hi all,

I wanted to report a bug (at least we belieave it is one). We had a
short discussion over at the archlinux bugtracker
(https://bugs.archlinux.org/task/60366).

In short:

> echo 'address=/ab--c.example.com/#' | dnsmasq --test -C -

> dnsmasq: error at line 1 of stdin

Althoug the URL is "forbidden":

> host 'ab--c.example.com'        
> host: 'ab--c.example.com' is not a legal IDNA2008 name (string
contains forbidden two hyphens pattern), use +noidnin

it would be nice to be able to block it. We ended up there, since the
filter list from
https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts started
to include these kinds of URLs.


My feeling is, that parsing the two dashes somehow fails. Interestingly,
adding one more character before the dashes does not trigger the bug:

> echo 'address=/abb--c.example.com/#' | dnsmasq --test -C -

> dnsmasq: syntax check OK.


Escaping (ab\-\-c.example.com) allows dnsmasq to start, but renders the
line ineffective.


Do you know about this and is it intended behaviour?


Regards,

Tasnad


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