[Dnsmasq-discuss] libidn2 issues with underscores on FreeBSD?

Discussion:

Matthias Andree

2017-07-06 20:51:34 UTC

Simon,

with the release of v2.77, I have switched the FreeBSD port from IDN
(which was used up to and including 2.76) to IDN2, and have just
received a bug report where SRV records that use underscores are no
longer recognized, and the reporter states that disabling the IDN2
option reinstates the expected operation:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=220521

Could you check that?

It appears we're using libidn2 v2.0.2 in FreeBSD, and previously used
libidn 1.33.

Thanks.

Best regards,
Matthias

Petr Menšík

2017-07-07 14:12:47 UTC

Permalink

Hi, I was the original contributor of IDN2 support.
I have to agree IDN2 does filter underscores out.

On Fedora 25:

$ idn2 --version
idn2 (libidn2) 2.0.2

$ idn2 -l _xmpp-server._tcp.domain.com
xmpp-server.tcp.domain.com

Not even transitional mode helps

$ idn2 -T _xmpp-server._tcp.domain.com
xmpp-server.tcp.domain.com

But older IDN works fine

$ idn --version
idn (GNU Libidn) 1.33

$ idn _xmpp-server._tcp.domain.com
_xmpp-server._tcp.domain.com

I will have have to ask why would it do that.

Another question is whether SRV records should be formatted by libidn2
when they will not be displayed to the user. I think it should affect
only logs but not served names themselves.

Post by Matthias Andree
Simon,
with the release of v2.77, I have switched the FreeBSD port from IDN
(which was used up to and including 2.76) to IDN2, and have just
received a bug report where SRV records that use underscores are no
longer recognized, and the reporter states that disabling the IDN2
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=220521
Could you check that?
It appears we're using libidn2 v2.0.2 in FreeBSD, and previously used
libidn 1.33.
Thanks.
Best regards,
Matthias
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Simon Kelley

2017-07-08 20:27:33 UTC

Permalink

I considered not passing SRV record names to IDN, but I can forsee
more subtle problems (We allow _ in hostnames, for instance.) So I've
fixed this, for some value of "fixed", by not passing any domain name
being parsed, which has one or more underscores, to IDN.

That seems a reasonable solution.

http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=69a815aa8f4b91570b562a54b43c3d44ac533e06

Cheers,

Simon

Post by Petr MenÅ¡Ãk
Hi, I was the original contributor of IDN2 support.
I have to agree IDN2 does filter underscores out.
$ idn2 --version
idn2 (libidn2) 2.0.2
$ idn2 -l _xmpp-server._tcp.domain.com
xmpp-server.tcp.domain.com
Not even transitional mode helps
$ idn2 -T _xmpp-server._tcp.domain.com
xmpp-server.tcp.domain.com
But older IDN works fine
$ idn --version
idn (GNU Libidn) 1.33
$ idn _xmpp-server._tcp.domain.com
_xmpp-server._tcp.domain.com
I will have have to ask why would it do that.
Another question is whether SRV records should be formatted by libidn2
when they will not be displayed to the user. I think it should affect
only logs but not served names themselves.

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Petr Menšík

2017-08-09 20:28:02 UTC

Permalink

Hi Simon,

this issue was fixed in libidn2 release of version 2.0.3. You workaround
could be disabled for releases with IDN2_VERSION_NUMBER >= 0x02000003.

Attaching small example patch.

Cheers,
Petr

Post by Simon Kelley
I considered not passing SRV record names to IDN, but I can forsee
more subtle problems (We allow _ in hostnames, for instance.) So I've
fixed this, for some value of "fixed", by not passing any domain name
being parsed, which has one or more underscores, to IDN.
That seems a reasonable solution.
http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=69a815aa8f4b91570b562a54b43c3d44ac533e06
Cheers,
Simon

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--
Petr MenÅ¡Ãk
Software Engineer
Red Hat, http://www.redhat.com/
email: ***@redhat.com PGP: 65C6C973

Matthias Andree

2017-08-17 18:38:19 UTC

Permalink

Post by Petr MenÅ¡Ãk
Hi Simon,
this issue was fixed in libidn2 release of version 2.0.3. You workaround
could be disabled for releases with IDN2_VERSION_NUMBER >= 0x02000003.
Attaching small example patch.
Cheers,
Petr

Hi everybody,

FreeBSD's ports of libidn2 (head, and the "2017Q3" quarterly branch) are
now updated to libidn2 v2.0.3, and I have not touched the dnsmasq
package for FreeBSD.
I believe that should fix the issues on a fully updated FreeBSD system
within a week or so.

Petr, thank you for all this information, most useful.

Cheers,
Matthias

Simon Kelley

2017-09-25 15:56:18 UTC

Permalink

Patch tweaked so it's not active with IDN1 either, and applied. Thanks.

Simon.

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