Re: Net::DNS::Resolver::Recurse issue

[parv]

What is the short runnable code that you had tried?

[gtech99]

I might add that indeed, the domain is misconfigured from multiple points of view.

1. Glue is missing

2. The non-glued NS is refusing queries

However, from what I read in the module's code, it should still work around this and circle back to the working NS

Right now my code works only if it falls by chance on the working NS

This is code from the module's source, I actually see it print "recover missing glue for .." in debug mode

sub _recurse {
    my ( $self, $query, $apex ) = @_;
    $self->_diag("using cached nameservers for $apex");
    my $cache  = $self->{persistent}->{$apex};
    my @nslist = keys %$cache;
    my @glue   = grep { $$cache{$_} } @nslist;
    my @noglue = grep { !$$cache{$_} } @nslist;
    my $reply;
    foreach my $ns ( @glue, @noglue ) {
        if ( my $iplist = $$cache{$ns} ) {
            $self->nameservers(@$iplist);
        } else {
            $self->_diag("recover missing glue for $ns");
            next if substr( lc($ns), -length($apex) ) eq $apex;
            my @ip = $self->nameservers($ns);
            $$cache{$ns} = \@ip;
        }
        $query->header->id(undef);
        last if $reply = $self->SUPER::send($query);
        $$cache{$ns} = undef;                # park non-responder
    }
    $self->_callback($reply);
    return unless $reply;
    my $zone = $self->_referral($reply) || return $reply;
    die '_recurse exceeded depth limit' if $self->{recurse_depth}++ > 
+50;
    my $qname  = lc( ( $query->question )[0]->qname );
    my $suffix = substr( $qname, -length($zone) );
    return $zone eq $suffix ? $self->_recurse( $query, $zone ) : undef
+;
}

[gtech99]

Oops, sorry. Really basic stuff. This fails on domains that have listed two nameservers, but only one provides actual answers because the other one is offline or misconfigured.

#!/usr/local/bin/perl

use Net::DNS::Resolver::Recurse;

my $res   = Net::DNS::Resolver::Recurse->new;

my $coderef = sub {
    my $packet = shift;

    printf ";; Received %d bytes from %s\n\n",
            $packet->answersize, $packet->answerfrom;
};

$res->callback($coderef);

$res->debug(0);

        my $reply = $res->query("test.com", "MX");
        if ($reply) {
                foreach $rr (grep { $_->type eq "MX" } $reply->answer)
                {
                        print $rr->exchange, $rr->preference, "\n";
                }
        } else {
                warn "query failed: ", $res->errorstring, "\n";
        }