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Do not treat a referral with a non-empty ANSWER section as an error

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As part of resquery_response() refactoring [1], a goto statement was
replaced [2] with a call to a new function - originally called
rctx_delegation(), now folded into rctx_answer_none() - extracted from
existing code.  However, one call site of that refactored function does
not reset the "result" variable, causing a referral with a non-empty
ANSWER section to be inadvertently treated as an error, which prevents
resolution of names reliant on servers sending such responses.  Fix by
resetting the "result" variable to ISC_R_SUCCESS when a response
containing a non-empty ANSWER section can be treated as a delegation.

[1] see RT #45362

[2] see commit e1380a16741a3b4a57e54d7a9ce09dd12691522f
This commit is contained in:
Michał Kępień 2018-08-22 10:12:53 +02:00
parent 3596bad5ce
commit 24b9ec555a
4 changed files with 18 additions and 1 deletions
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4
bin/tests/system/resolver/ans2/ans.pl
View file

@ -107,6 +107,10 @@ for (;;) {
# expected to be accepted regardless of the filter setting.
$packet->push("authority", new Net::DNS::RR("sub.example.org 300 NS ns.sub.example.org"));
$packet->push("additional", new Net::DNS::RR("ns.sub.example.org 300 A 10.53.0.3"));
} elsif ($qname =~ /glue-in-answer\.example\.org/) {
$packet->push("answer", new Net::DNS::RR("ns.glue-in-answer.example.org 300 A 10.53.0.3"));
$packet->push("authority", new Net::DNS::RR("glue-in-answer.example.org 300 NS ns.glue-in-answer.example.org"));
$packet->push("additional", new Net::DNS::RR("ns.glue-in-answer.example.org 300 A 10.53.0.3"));
} elsif ($qname =~ /\.broken/ || $qname =~ /^broken/) {
# Delegation to broken TLD.
$packet->push("authority", new Net::DNS::RR("broken 300 NS ns.broken"));

2
bin/tests/system/resolver/ans3/ans.pl
View file

@ -107,6 +107,8 @@ for (;;) {
} elsif ($qname eq "www.ok.sub.example.org") {
$packet->push("answer",
new Net::DNS::RR($qname . " 300 A 192.0.2.1"));
} elsif ($qname eq "foo.glue-in-answer.example.org") {
$packet->push("answer", new Net::DNS::RR($qname . " 300 A 192.0.2.1"));
} else {
$packet->push("answer", new Net::DNS::RR("www.example.com 300 A 1.2.3.4"));
}

9
bin/tests/system/resolver/tests.sh
View file

@ -247,6 +247,15 @@ if [ -x ${RESOLVE} ] ; then
status=`expr $status + $ret`
fi
n=`expr $n + 1`
echo_i "check that the resolver accepts a referral response with a non-empty ANSWER section ($n)"
ret=0
$DIG $DIGOPTS @10.53.0.1 foo.glue-in-answer.example.org. A > dig.ns1.out.${n} || ret=1
grep "status: NOERROR" dig.ns1.out.${n} > /dev/null || ret=1
grep "foo.glue-in-answer.example.org.*192.0.2.1" dig.ns1.out.${n} > /dev/null || ret=1
if [ $ret != 0 ]; then echo_i "failed"; fi
status=`expr $status + $ret`
n=`expr $n + 1`
echo_i "RT21594 regression test check setup ($n)"
ret=0

4
lib/dns/resolver.c
View file

@ -7881,7 +7881,9 @@ rctx_answer(respctx_t *rctx) {
}
}
if (result != DNS_R_DELEGATION) {
if (result == DNS_R_DELEGATION) {
result = ISC_R_SUCCESS;
} else {
/*
* At this point, AA is not set, the response
* is not a referral, and the server is not a