Bug #122808 for Net-DNS: Net::DNS::Resolver 1.11 cannot get a reply once udppacketsize is set to 512 (PACKETSZ)

Tue Aug 15 11:35:53 2017 nick [...] cpanel.net - Ticket created

Subject:

Net::DNS::Resolver 1.11 cannot get a reply once udppacketsize is set to 512 (PACKETSZ)

In the below example after setting udppacketsize to 512 (PACKETSZ) a response is no longer possible. #!/usr/bin/env perl # use strict; use warnings; use Net::DNS 1.11 (); use Net::DNS::Resolver (); use Test::More tests => 3; my $domain_that_requires_noedns = 'boarderhouse.ch'; # dig boarderhouse.ch @dns1.mhs.ch +noedns +short ok my $resolver = Net::DNS::Resolver->new(); $resolver->recurse(0); $resolver->usevc(0); $resolver->nameservers('213.188.32.64'); my $reply_before = $resolver->query( $domain_that_requires_noedns, 'A' ); ok( $reply_before, "Reply received when udppacketsize unset" ); $resolver->udppacketsize(0); my $reply_after_zero_packet_size = $resolver->query( $domain_that_requires_noedns, 'A' ); ok( $reply_after_zero_packet_size, "Reply received when udppacketsize set to 0" ); $resolver->udppacketsize( Net::DNS::Resolver::Base::PACKETSZ() ); my $reply_after_packetsz_packet_size = $resolver->query( $domain_that_requires_noedns, 'A' ); ok( $reply_after_packetsz_packet_size, "Reply received when udppacketsize set to PACKETSZ (512)" );

Tue Aug 15 11:41:01 2017 nick [...] cpanel.net - Correspondence added

Also this is a regression from 1.08 as this code works as expected on 1.08

Tue Aug 15 11:51:55 2017 nick [...] cpanel.net - Correspondence added

It appears EDNS is set in the packet when its set to 512

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Tue Aug 15 11:57:11 2017 nick [...] cpanel.net - Correspondence added

Net/DNS/RR/OPT.pm This appears to resolve the problem: -return $UDP_size < 512 ? 512 : ( $_ = $UDP_size ) unless $_; +return $UDP_size <= 512 ? 512 : ( $_ = $UDP_size ) unless $_;

Wed Aug 16 10:12:03 2017 rwfranks [...] acm.org - Correspondence added

From:

rwfranks [...] acm.org

On Tue Aug 15 11:57:11 2017, bdraco wrote: Show quoted text

> > Net/DNS/RR/OPT.pm > > This appears to resolve the problem: > > -return $UDP_size < 512 ? 512 : ( $_ = $UDP_size ) unless $_; > +return $UDP_size <= 512 ? 512 : ( $_ = $UDP_size ) unless $_;

But it does not. It just reintroduces problem RT#122138.

Wed Aug 16 10:12:04 2017 The RT System itself - Status changed from 'new' to 'open'

Wed Aug 16 10:30:46 2017 rwfranks [...] acm.org - Correspondence added

From:

rwfranks [...] acm.org

On Tue Aug 15 11:35:53 2017, bdraco wrote: Show quoted text

> In the below example after setting udppacketsize to 512 (PACKETSZ) a > response is no longer possible.

The size of udppacketsize is immaterial. Your nameserver returns FORMERR indicating lack of support for EDNS as required by RFC6891. $ cat RT122808.pl #!/usr/bin/perl # use Net::DNS; my $resolver = new Net::DNS::Resolver( nameserver => 'dns2.mhs.ch', udppacketsize => 1280 ); $resolver->debug(1); my $reply = $resolver->send( 'mhs.ch', 'SOA' ); __END__ $ perl RT122808.pl ;; udp send [213.188.32.64]:53 ;; answer from [213.188.32.64] 12 bytes ;; HEADER SECTION ;; id = 31776 ;; qr = 1 aa = 0 tc = 0 rd = 1 opcode = QUERY ;; ra = 0 z = 0 ad = 0 cd = 0 rcode = FORMERR ;; qdcount = 0 ancount = 0 nscount = 0 arcount = 0 ;; do = 0 ;; QUESTION SECTION (0 records) ;; ANSWER SECTION (0 records) ;; AUTHORITY SECTION (0 records) ;; ADDITIONAL SECTION (0 records) ;; errorstring: FORMERR

Wed Aug 16 10:40:20 2017 nick [...] cpanel.net - Correspondence added

Hi Dick, This is mostly a problem when we change the udppacketsize to a defined value, and than want to restore the default behavior. Since udppacketsize is 0 inside the object, can we safely assume that $resolver->udppacketsize(0); will restore the default behavior and not break in the future? The current method we are using is to set it to PACKETSZ. On Tue Aug 15 11:35:53 2017, bdraco wrote: Show quoted text

> In the below example after setting udppacketsize to 512 (PACKETSZ) a > response is no longer possible. > > > #!/usr/bin/env perl > # > use strict; > use warnings; > > use Net::DNS 1.11 (); > use Net::DNS::Resolver (); > use Test::More tests => 3; > > my $domain_that_requires_noedns = 'boarderhouse.ch'; # dig > boarderhouse.ch @dns1.mhs.ch +noedns +short ok > my $resolver = Net::DNS::Resolver->new(); > > $resolver->recurse(0); > $resolver->usevc(0); > $resolver->nameservers('213.188.32.64'); > > my $reply_before = $resolver->query( $domain_that_requires_noedns, 'A' > ); > ok( $reply_before, "Reply received when udppacketsize unset" ); > > $resolver->udppacketsize(0); > > my $reply_after_zero_packet_size = $resolver->query( > $domain_that_requires_noedns, 'A' ); > ok( $reply_after_zero_packet_size, "Reply received when udppacketsize > set to 0" ); > > $resolver->udppacketsize( Net::DNS::Resolver::Base::PACKETSZ() ); > > my $reply_after_packetsz_packet_size = $resolver->query( > $domain_that_requires_noedns, 'A' ); > ok( $reply_after_packetsz_packet_size, "Reply received when > udppacketsize set to PACKETSZ (512)" );

Wed Aug 16 11:07:26 2017 rwfranks [...] acm.org - Correspondence added

From:

rwfranks [...] acm.org

On Wed Aug 16 10:40:20 2017, bdraco wrote: Show quoted text

> Hi Dick, > > This is mostly a problem when we change the udppacketsize to a defined > value, and than want to restore the default behavior. > > Since udppacketsize is 0 inside the object, can we safely assume that > > $resolver->udppacketsize(0); > > will restore the default behavior and not break in the future? > > The current method we are using is to set it to PACKETSZ. >

udppacketsize advertises a characteristic of the local IP infrastructure, which does not change on a per-transaction basis. Your nameserver does not understand EDNS, so it is meaningless to specify the maximum size of packet it can send back to you.

Wed Aug 16 11:11:37 2017 nick [...] cpanel.net - Correspondence added

Thanks. We will move forward with that solution. On Wed Aug 16 11:07:26 2017, rwfranks@acm.org wrote: Show quoted text

> On Wed Aug 16 10:40:20 2017, bdraco wrote:

> > Hi Dick, > > > > This is mostly a problem when we change the udppacketsize to a > > defined > > value, and than want to restore the default behavior. > > > > Since udppacketsize is 0 inside the object, can we safely assume that > > > > $resolver->udppacketsize(0); > > > > will restore the default behavior and not break in the future? > > > > The current method we are using is to set it to PACKETSZ. > >

> > udppacketsize advertises a characteristic of the local IP > infrastructure, which does not change on a per-transaction basis. > > Your nameserver does not understand EDNS, so it is meaningless to > specify the maximum size of packet it can send back to you.

Wed Aug 23 05:40:39 2017 NLNETLABS [...] cpan.org - Status changed from 'open' to 'rejected'