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4377. [bug] Don't reuse zero TTL responses beyond the current

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client set (excludes ANY/SIG/RRSIG queries).
                        [RT #42142]
This commit is contained in:
Mark Andrews
2016-05-27 09:59:46 +10:00
parent 6c2a76b3e2
commit aabcb1fde0
5 changed files with 164 additions and 0 deletions
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4
CHANGES
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@@ -1,3 +1,7 @@
4377. [bug] Don't reuse zero TTL responses beyond the current
client set (excludes ANY/SIG/RRSIG queries).
[RT #42142]
4376. [experimental] Added support for Catalog Zones, a new method for
provisioning secondary servers in which a list of
zones to be served is stored in a DNS zone and can

64
bin/named/query.c
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@@ -8065,6 +8065,38 @@ query_find(ns_client_t *client, dns_fetchevent_t *event, dns_rdatatype_t qtype)
goto cleanup;
case DNS_R_CNAME:
/*
* If we have a zero ttl from the cache refetch it.
*/
if (!is_zone && event == NULL && rdataset->ttl == 0 &&
RECURSIONOK(client))
{
if (dns_rdataset_isassociated(rdataset))
dns_rdataset_disassociate(rdataset);
if (sigrdataset != NULL &&
dns_rdataset_isassociated(sigrdataset))
dns_rdataset_disassociate(sigrdataset);
if (node != NULL)
dns_db_detachnode(db, &node);
INSIST(!REDIRECT(client));
result = query_recurse(client, qtype,
client->query.qname,
NULL, NULL, resuming);
if (result == ISC_R_SUCCESS) {
client->query.attributes |=
NS_QUERYATTR_RECURSING;
if (dns64)
client->query.attributes |=
NS_QUERYATTR_DNS64;
if (dns64_exclude)
client->query.attributes |=
NS_QUERYATTR_DNS64EXCLUDE;
} else
RECURSE_ERROR(result);
goto cleanup;
}
/*
* Keep a copy of the rdataset. We have to do this because
* query_addrrset may clear 'rdataset' (to prevent the
@@ -8505,6 +8537,38 @@ query_find(ns_client_t *client, dns_fetchevent_t *event, dns_rdatatype_t qtype)
* we know the answer.
*/
/*
* If we have a zero ttl from the cache refetch it.
*/
if (!is_zone && event == NULL && rdataset->ttl == 0 &&
RECURSIONOK(client))
{
if (dns_rdataset_isassociated(rdataset))
dns_rdataset_disassociate(rdataset);
if (sigrdataset != NULL &&
dns_rdataset_isassociated(sigrdataset))
dns_rdataset_disassociate(sigrdataset);
if (node != NULL)
dns_db_detachnode(db, &node);
INSIST(!REDIRECT(client));
result = query_recurse(client, qtype,
client->query.qname,
NULL, NULL, resuming);
if (result == ISC_R_SUCCESS) {
client->query.attributes |=
NS_QUERYATTR_RECURSING;
if (dns64)
client->query.attributes |=
NS_QUERYATTR_DNS64;
if (dns64_exclude)
client->query.attributes |=
NS_QUERYATTR_DNS64EXCLUDE;
} else
RECURSE_ERROR(result);
goto cleanup;
}
#ifdef ALLOW_FILTER_AAAA
/*
* Optionally hide AAAAs from IPv4 clients if there is an A.

81
bin/tests/system/zero/ans5/ans.pl Normal file
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@@ -0,0 +1,81 @@
#!/usr/bin/perl -w
#
# Copyright (C) 2015 Internet Systems Consortium, Inc. ("ISC")
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
# OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.
#
# Don't respond if the "norespond" file exists; otherwise respond to
# any A or AAAA query.
#
use IO::File;
use IO::Socket;
use Net::DNS;
use Net::DNS::Packet;
my $sock = IO::Socket::INET->new(LocalAddr => "10.53.0.5",
LocalPort => 5300, Proto => "udp") or die "$!";
my $pidf = new IO::File "ans.pid", "w" or die "cannot open pid file: $!";
print $pidf "$$\n" or die "cannot write pid file: $!";
$pidf->close or die "cannot close pid file: $!";
sub rmpid { unlink "ans.pid"; exit 1; };
$SIG{INT} = \&rmpid;
$SIG{TERM} = \&rmpid;
my $octet = 0;
for (;;) {
$sock->recv($buf, 512);
print "**** request from " , $sock->peerhost, " port ", $sock->peerport, "\n";
my $packet;
if ($Net::DNS::VERSION > 0.68) {
$packet = new Net::DNS::Packet(\$buf, 0);
$@ and die $@;
} else {
my $err;
($packet, $err) = new Net::DNS::Packet(\$buf, 0);
$err and die $err;
}
print "REQUEST:\n";
$packet->print;
$packet->header->qr(1);
my @questions = $packet->question;
my $qname = $questions[0]->qname;
my $qtype = $questions[0]->qtype;
$packet->header->aa(1);
if ($qtype eq "A") {
$packet->push("answer",
new Net::DNS::RR($qname .
" 0 A 192.0.2." . $octet));
$octet = $octet + 1;
} elsif ($qtype eq "AAAA") {
$packet->push("answer",
new Net::DNS::RR($qname .
" 300 AAAA 2001:db8:beef::1"));
}
$sock->send($packet->data);
print "RESPONSE:\n";
$packet->print;
print "\n";
}

2
bin/tests/system/zero/ns1/root.db
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@@ -22,3 +22,5 @@ example. NS ns2.example.
ns2.example. A 10.53.0.2
example. NS ns4.example.
ns4.example. A 10.53.0.4
increment. NS incrementns.
incrementns A 10.53.0.5

13
bin/tests/system/zero/tests.sh
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@@ -44,5 +44,18 @@ done
if [ $ret != 0 ]; then echo "I:failed"; fi
status=`expr $status + $ret`
echo "I:check repeated recursive lookups of non recurring zero ttl responses get new values"
count=`(
dig +short -p 5300 @10.53.0.3 foo.increment
dig +short -p 5300 @10.53.0.3 foo.increment
dig +short -p 5300 @10.53.0.3 foo.increment
dig +short -p 5300 @10.53.0.3 foo.increment
dig +short -p 5300 @10.53.0.3 foo.increment
dig +short -p 5300 @10.53.0.3 foo.increment
dig +short -p 5300 @10.53.0.3 foo.increment
) | sort -u | wc -l `
if [ $count -ne 7 ] ; then echo "I:failed (count=$count)"; ret=1; fi
status=`expr $status + $ret`
echo "I:exit status: $status"
exit $status