[PATCH] bug #10471: Don't respond with NXDOMAIN to records that exist with another type

Kai Blin kai at samba.org
Thu Feb 27 15:52:10 MST 2014


DNS queries for records with the wrong type need to trigger an empty
response with RCODE_OK instead of returning NXDOMAIN.

This adds a test and fixes bug #10471

Signed-off-by: Kai Blin <kai at samba.org>
---
 python/samba/tests/dns.py      | 16 ++++++++++++++++
 source4/dns_server/dns_query.c | 14 ++++++++------
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/python/samba/tests/dns.py b/python/samba/tests/dns.py
index 0ac9cf4..bac8dea 100644
--- a/python/samba/tests/dns.py
+++ b/python/samba/tests/dns.py
@@ -171,6 +171,22 @@ class TestSimpleQueries(DNSTest):
         self.assertEquals(response.answers[0].rdata,
                           os.getenv('SERVER_IP'))
 
+    def test_one_mx_query(self):
+        "create a query packet causing an empty RCODE_OK answer"
+        p = self.make_name_packet(dns.DNS_OPCODE_QUERY)
+        questions = []
+
+        name = "%s.%s" % (os.getenv('SERVER'), self.get_dns_domain())
+        q = self.make_name_question(name, dns.DNS_QTYPE_MX, dns.DNS_QCLASS_IN)
+        print "asking for ", q.name
+        questions.append(q)
+
+        self.finish_name_packet(p, questions)
+        response = self.dns_transaction_udp(p)
+        self.assert_dns_rcode_equals(response, dns.DNS_RCODE_OK)
+        self.assert_dns_opcode_equals(response, dns.DNS_OPCODE_QUERY)
+        self.assertEquals(response.ancount, 0)
+
     def test_two_queries(self):
         "create a query packet containing two query records"
         p = self.make_name_packet(dns.DNS_OPCODE_QUERY)
diff --git a/source4/dns_server/dns_query.c b/source4/dns_server/dns_query.c
index 5414e1d..77f797b 100644
--- a/source4/dns_server/dns_query.c
+++ b/source4/dns_server/dns_query.c
@@ -258,7 +258,7 @@ static WERROR handle_question(struct dns_server *dns,
 			      struct dns_res_rec **answers, uint16_t *ancount)
 {
 	struct dns_res_rec *ans = *answers;
-	WERROR werror;
+	WERROR werror, werror_return;
 	unsigned int ri;
 	struct dnsp_DnssrvRpcRecord *recs;
 	uint16_t rec_count, ai = *ancount;
@@ -275,6 +275,9 @@ static WERROR handle_question(struct dns_server *dns,
 		return WERR_NOMEM;
 	}
 
+	/* Set up for an NXDOMAIN reply if no match is found */
+	werror_return = DNS_ERR(NAME_ERROR);
+
 	for (ri = 0; ri < rec_count; ri++) {
 		if ((recs[ri].wType == DNS_TYPE_CNAME) &&
 		    ((question->question_type == DNS_QTYPE_A) ||
@@ -319,28 +322,27 @@ static WERROR handle_question(struct dns_server *dns,
 			if (!W_ERROR_IS_OK(werror)) {
 				return werror;
 			}
+			werror_return = WERR_OK;
 
 
 			continue;
 		}
 		if ((question->question_type != DNS_QTYPE_ALL) &&
 		    (recs[ri].wType != question->question_type)) {
+			werror_return = WERR_OK;
 			continue;
 		}
 		werror = create_response_rr(question, &recs[ri], &ans, &ai);
 		if (!W_ERROR_IS_OK(werror)) {
 			return werror;
 		}
-	}
-
-	if (ai == 0) {
-		return DNS_ERR(NAME_ERROR);
+		werror_return = WERR_OK;
 	}
 
 	*ancount = ai;
 	*answers = ans;
 
-	return WERR_OK;
+	return werror_return;
 }
 
 static NTSTATUS create_tkey(struct dns_server *dns,
-- 
1.8.1.2



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