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Merge branch '3678-serve-stale-servfailing-unexpectedly' into 'main'

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Resolve "stale-serve and RPZ put in SERVFAIL cache unexpected record"

Closes #3678

See merge request isc-projects/bind9!7096
This commit is contained in:
Arаm Sаrgsyаn
2022-12-06 14:53:16 +00:00
parent 84a7be327e 5b5f3a0ea7
commit 629f66ea8e
4 changed files with 111 additions and 0 deletions
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5
CHANGES
View File

@@ -1,3 +1,8 @@
6038. [bug] In some serve stale scenarios, like when following an
expired CNAME record, named could return SERVFAIL if the
previous request wasn't successful. Consider non-stale
data when in serve-stale mode. [GL #3678]
6037. [func] Reject zones which have DS records not at delegation
points. [GL #3697]

24
bin/tests/system/serve-stale/ans2/ans.pl
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@@ -58,6 +58,8 @@ my $CAA = "othertype.example 2 IN CAA 0 issue \"ca1.example.net\"";
my $negSOA = "example 2 IN SOA . . 0 0 0 0 300";
my $CNAME = "cname.example 7 IN CNAME target.example";
my $TARGET = "target.example 9 IN A $localaddr";
my $SHORTCNAME = "shortttl.cname.example 1 IN CNAME longttl.target.example";
my $LONGTARGET = "longttl.target.example 600 IN A $localaddr";
sub reply_handler {
my ($qname, $qclass, $qtype) = @_;
@@ -166,6 +168,28 @@ sub reply_handler {
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "shortttl.cname.example") {
if ($qtype eq "A") {
my $rr = new Net::DNS::RR($SHORTCNAME);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "longttl.target.example") {
if ($slow_response) {
print " Sleeping 3 seconds\n";
sleep(3);
}
if ($qtype eq "A") {
my $rr = new Net::DNS::RR($LONGTARGET);
push @ans, $rr;
} else {
my $rr = new Net::DNS::RR($negSOA);
push @auth, $rr;
}
$rcode = "NOERROR";
} elsif ($qname eq "longttl.example") {
if ($qtype eq "TXT") {
my $rr = new Net::DNS::RR($LONGTXT);

74
bin/tests/system/serve-stale/tests.sh
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@@ -1829,6 +1829,80 @@ grep "data\.example\..*[12].*IN.*TXT.*A text record with a 2 second ttl" dig.out
if [ $ret != 0 ]; then echo_i "failed"; fi
status=$((status+ret))
##############################################################
# Test for stale-answer-client-timeout off and CNAME record. #
##############################################################
echo_i "test stale-answer-client-timeout (0) and CNAME record"
n=$((n+1))
echo_i "prime cache shortttl.cname.example (stale-answer-client-timeout off) ($n)"
ret=0
$DIG -p ${PORT} @10.53.0.3 shortttl.cname.example A > dig.out.test$n
grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
grep "ANSWER: 2," dig.out.test$n > /dev/null || ret=1
grep "shortttl\.cname\.example\..*1.*IN.*CNAME.*longttl\.target\.example\." dig.out.test$n > /dev/null || ret=1
grep "longttl\.target\.example\..*600.*IN.*A.*10\.53\.0\.2" dig.out.test$n > /dev/null || ret=1
if [ $ret != 0 ]; then echo_i "failed"; fi
status=$((status+ret))
# Allow RRset to become stale.
sleep 1
n=$((n+1))
echo_i "disable responses from authoritative server ($n)"
ret=0
$DIG -p ${PORT} @10.53.0.2 txt disable > dig.out.test$n
grep "ANSWER: 1," dig.out.test$n > /dev/null || ret=1
grep "TXT.\"0\"" dig.out.test$n > /dev/null || ret=1
if [ $ret != 0 ]; then echo_i "failed"; fi
status=$((status+ret))
n=$((n+1))
ret=0
echo_i "check stale shortttl.cname.example comes from cache (stale-answer-client-timeout off) ($n)"
nextpart ns3/named.run > /dev/null
$DIG -p ${PORT} @10.53.0.3 shortttl.cname.example A > dig.out.test$n
wait_for_log 5 "shortttl.cname.example A resolver failure, stale answer used" ns3/named.run || ret=1
grep "status: NOERROR" dig.out.test$n > /dev/null || ret=1
grep "EDE: 3 (Stale Answer): (resolver failure)" dig.out.test$n > /dev/null || ret=1
grep "ANSWER: 2," dig.out.test$n > /dev/null || ret=1
grep "shortttl\.cname\.example\..*3.*IN.*CNAME.*longttl\.target\.example\." dig.out.test$n > /dev/null || ret=1
# We can't reliably test the TTL of the longttl.target.example A record.
grep "longttl\.target\.example\..*IN.*A.*10\.53\.0\.2" dig.out.test$n > /dev/null || ret=1
if [ $ret != 0 ]; then echo_i "failed"; fi
status=$((status+ret))
n=$((n+1))
echo_i "enable responses from authoritative server ($n)"
ret=0
$DIG -p ${PORT} @10.53.0.2 txt enable > dig.out.test$n
grep "ANSWER: 1," dig.out.test$n > /dev/null || ret=1
grep "TXT.\"1\"" dig.out.test$n > /dev/null || ret=1
if [ $ret != 0 ]; then echo_i "failed"; fi
status=$((status+ret))
n=$((n+1))
echo_i "check server is alive or restart ($n)"
ret=0
$RNDCCMD 10.53.0.3 status > rndc.out.test$n 2>&1 || ret=1
if [ $ret != 0 ]; then
echo_i "failed"
echo_i "restart ns3"
start_server --noclean --restart --port ${PORT} serve-stale ns3
fi
status=$((status+ret))
n=$((n+1))
echo_i "check server is alive or restart ($n)"
ret=0
$RNDCCMD 10.53.0.3 status > rndc.out.test$n 2>&1 || ret=1
if [ $ret != 0 ]; then
echo_i "failed"
echo_i "restart ns3"
start_server --noclean --restart --port ${PORT} serve-stale ns3
fi
status=$((status+ret))
#############################################
# Test for stale-answer-client-timeout 0. #
#############################################

8
lib/ns/query.c
View File

@@ -5960,6 +5960,13 @@ query_lookup(query_ctx_t *qctx) {
dns_cache_updatestats(qctx->view->cache, result);
}
if (dns_rdataset_isassociated(qctx->rdataset) &&
dns_rdataset_count(qctx->rdataset) > 0 && !STALE(qctx->rdataset))
{
/* Found non-stale usable rdataset. */
goto gotanswer;
}
/*
* If DNS_DBFIND_STALEOK is set this means we are dealing with a
* lookup following a failed lookup and it is okay to serve a stale
@@ -6131,6 +6138,7 @@ query_lookup(query_ctx_t *qctx) {
qctx->rdataset->attributes |= DNS_RDATASETATTR_STALE_ADDED;
}
gotanswer:
result = query_gotanswer(qctx, result);
cleanup: