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commit 524f5c0d8fa5bd55c98243be889528f48437a2f7
Author: Mark Andrews <marka@isc.org>
Date: Fri Dec 9 12:50:18 2016 +1100
4530. [bug] Change 4489 broke the handling of CNAME -> DNAME
in responses resulting in SERVFAIL being returned.
[RT #43779]
(cherry picked from commit 60cb462c56536f307fac4db8bdebf1247e2b5f66)
diff --git a/bin/tests/system/dname/ns2/example.db b/bin/tests/system/dname/ns2/example.db
index ece3506..4289134 100644
--- a/bin/tests/system/dname/ns2/example.db
+++ b/bin/tests/system/dname/ns2/example.db
@@ -29,4 +29,6 @@ a.short A 10.0.0.1
short-dname DNAME short
a.longlonglonglonglonglonglonglonglonglonglonglonglong A 10.0.0.2
long-dname DNAME longlonglonglonglonglonglonglonglonglonglonglonglong
-;
+cname CNAME a.cnamedname
+cnamedname DNAME target
+a.target A 10.0.0.3
diff --git a/bin/tests/system/dname/tests.sh b/bin/tests/system/dname/tests.sh
index d22f54b..04bfcb2 100644
--- a/bin/tests/system/dname/tests.sh
+++ b/bin/tests/system/dname/tests.sh
@@ -63,6 +63,24 @@ grep "status: YXDOMAIN" dig.out.ns4.toolong > /dev/null || ret=1
if [ $ret != 0 ]; then echo "I:failed"; fi
status=`expr $status + $ret`
+echo "I:checking cname to dname from authoritative"
+ret=0
+$DIG cname.example @10.53.0.2 a -p 5300 > dig.out.ns2.cname
+grep "status: NOERROR" dig.out.ns2.cname > /dev/null || ret=1
+if [ $ret != 0 ]; then echo "I:failed"; fi
+status=`expr $status + $ret`
+
+echo "I:checking cname to dname from recursive"
+ret=0
+$DIG cname.example @10.53.0.4 a -p 5300 > dig.out.ns4.cname
+grep "status: NOERROR" dig.out.ns4.cname > /dev/null || ret=1
+grep '^cname.example.' dig.out.ns4.cname > /dev/null || ret=1
+grep '^cnamedname.example.' dig.out.ns4.cname > /dev/null || ret=1
+grep '^a.cnamedname.example.' dig.out.ns4.cname > /dev/null || ret=1
+grep '^a.target.example.' dig.out.ns4.cname > /dev/null || ret=1
+if [ $ret != 0 ]; then echo "I:failed"; fi
+status=`expr $status + $ret`
+
echo "I:exit status: $status"
exit $status
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 4bef072..de80928 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -6463,7 +6463,7 @@ static isc_result_t
answer_response(fetchctx_t *fctx) {
isc_result_t result;
dns_message_t *message;
- dns_name_t *name, *dname = NULL, *qname, *dqname, tname, *ns_name;
+ dns_name_t *name, *dname = NULL, *qname, tname, *ns_name;
dns_name_t *cname = NULL;
dns_rdataset_t *rdataset, *ns_rdataset;
isc_boolean_t done, external, chaining, aa, found, want_chaining;
@@ -6471,7 +6471,7 @@ answer_response(fetchctx_t *fctx) {
isc_boolean_t wanted_chaining;
unsigned int aflag;
dns_rdatatype_t type;
- dns_fixedname_t fdname, fqname, fqdname;
+ dns_fixedname_t fdname, fqname;
dns_view_t *view;
FCTXTRACE("answer_response");
@@ -6495,13 +6495,12 @@ answer_response(fetchctx_t *fctx) {
aa = ISC_TRUE;
else
aa = ISC_FALSE;
- dqname = qname = &fctx->name;
+ qname = &fctx->name;
type = fctx->type;
view = fctx->res->view;
- dns_fixedname_init(&fqdname);
result = dns_message_firstname(message, DNS_SECTION_ANSWER);
while (!done && result == ISC_R_SUCCESS) {
- dns_namereln_t namereln, dnamereln;
+ dns_namereln_t namereln;
int order;
unsigned int nlabels;
@@ -6509,8 +6508,6 @@ answer_response(fetchctx_t *fctx) {
dns_message_currentname(message, DNS_SECTION_ANSWER, &name);
external = ISC_TF(!dns_name_issubdomain(name, &fctx->domain));
namereln = dns_name_fullcompare(qname, name, &order, &nlabels);
- dnamereln = dns_name_fullcompare(dqname, name, &order,
- &nlabels);
if (namereln == dns_namereln_equal) {
wanted_chaining = ISC_FALSE;
for (rdataset = ISC_LIST_HEAD(name->list);
@@ -6763,11 +6760,24 @@ answer_response(fetchctx_t *fctx) {
return (DNS_R_FORMERR);
}
- if (dnamereln != dns_namereln_subdomain) {
+ /*
+ * If DNAME + synthetic CNAME then the
+ * namereln is dns_namereln_subdomain.
+ *
+ * If synthetic CNAME + DNAME then the
+ * namereln is dns_namereln_commonancestor
+ * and the number of label must match the
+ * DNAME. This order is not RFC compliant.
+ */
+
+ if (namereln != dns_namereln_subdomain &&
+ (namereln != dns_namereln_commonancestor ||
+ nlabels != dns_name_countlabels(name)))
+ {
char qbuf[DNS_NAME_FORMATSIZE];
char obuf[DNS_NAME_FORMATSIZE];
- dns_name_format(dqname, qbuf,
+ dns_name_format(qname, qbuf,
sizeof(qbuf));
dns_name_format(name, obuf,
sizeof(obuf));
@@ -6782,7 +6792,7 @@ answer_response(fetchctx_t *fctx) {
want_chaining = ISC_TRUE;
POST(want_chaining);
aflag = DNS_RDATASETATTR_ANSWER;
- result = dname_target(rdataset, dqname,
+ result = dname_target(rdataset, qname,
nlabels, &fdname);
if (result == ISC_R_NOSPACE) {
/*
@@ -6799,13 +6809,11 @@ answer_response(fetchctx_t *fctx) {
dname = dns_fixedname_name(&fdname);
if (!is_answertarget_allowed(view,
- dqname, rdataset->type,
+ qname, rdataset->type,
dname, &fctx->domain))
{
return (DNS_R_SERVFAIL);
}
- dqname = dns_fixedname_name(&fqdname);
- dns_name_copy(dname, dqname, NULL);
} else {
/*
* We've found a signature that
@@ -6951,7 +6959,8 @@ answer_response(fetchctx_t *fctx) {
rdataset->trust =
dns_trust_additional;
- if (rdataset->type == dns_rdatatype_ns) {
+ if (rdataset->type == dns_rdatatype_ns)
+ {
ns_name = name;
ns_rdataset = rdataset;
}