Bug #132921 for Net-DNS: EDNS OPT handling

Wed Jul 01 09:19:55 2020 ray [...] isc.org - Ticket created

Subject:	EDNS OPT handling
Date:	Wed, 1 Jul 2020 13:59:53 +0100
To:	bug-Net-DNS [...] rt.cpan.org
From:	Ray Bellis <ray [...] isc.org>

With latest (1.25) explicitly setting the `edns->version()` on a packet is unsufficient to trigger adding an OPT RR. To resolve this, the "version" property should be added to the list of fields checked in the `_specified` method of Net::DNS::RR:OPT. A further confusion arises from the use of `packet->edns->size()` which is ignored when you pass a packet to Net::DNS::Resolver.send() and is promptly overwritten by the Resolver object's own `udppacketsize` property. I'm unsure of the right fix, but I'd suggest that if the packet's EDNS size has been explicitly specified that it shouldn't then get overwritten internally within Net::DNS. If I pass a packet to `send()` I'd rather hope that that's the packet that actually gets sent! :) cheers, Ray

Fri Jul 03 13:48:15 2020 rwfranks [...] acm.org - Correspondence added

On Wed Jul 01 09:19:55 2020, ray@isc.org wrote: Show quoted text

> With latest (1.25) explicitly setting the `edns->version()` on a packet > is unsufficient to trigger adding an OPT RR.

This is not peculiar to 1.25. OPT has never been added into a query by setting $packet->edns->version(1) alone. Prior to 1.21, it was not possible to specify the version at all. Show quoted text

> To resolve this, the "version" property should be added to the list of > fields checked in the `_specified` method of Net::DNS::RR:OPT.

The version in an EDNS OPT RR advertises the capabilities of the implementation that created it. With that world view, setting edns->version makes little sense in general. Neither is this essential for creating a test query to elicit a BADVERS error response from a nameserver. my $query = new Net::DNS::Packet( "example.com.", "SOA" ); $query->edns->version(1); $query->edns->option(65500 => 1); # ignored per RFC6891 6.1.2 Show quoted text

> A further confusion arises from the use of `packet->edns->size()` which > is ignored when you pass a packet to Net::DNS::Resolver.send() and is > promptly overwritten by the Resolver object's `udppacketsize` property.

The present code regards EDNS packet size as a resolver configuration attribute and fails to recognise that this might be specified in a query. Show quoted text

> If I pass a packet to `send()` I'd rather hope that that's the packet > that actually gets sent! :)

Agree

Fri Jul 03 13:48:16 2020 The RT System itself - Status changed from 'new' to 'open'

Tue Jul 28 13:35:15 2020 rwfranks [...] acm.org - Fixed in 1.25_01 added

Wed Sep 02 03:46:54 2020 NLNETLABS [...] cpan.org - Correspondence added

Resolved in Net::DNS 1.26

Wed Sep 02 03:46:56 2020 NLNETLABS [...] cpan.org - Status changed from 'open' to 'resolved'