dns: Delete dnsNode objects when they are empty

If an update leaves the dnsNode without any entries, the dnsNode object
should be deleted. Thanks to Günter Kukkukk for his excellent debugging
work on this one.

This should fix bug #9559

Signed-off-by: Kai Blin <kai@samba.org>

Reviewed-by: Andrew Bartlett <abartlet@samba.org>

2 files changed, 124 insertions, 1 deletions

diff --git a/python/samba/tests/dns.py b/python/samba/tests/dns.py
index 15672a0b00..0ac9cf4b8b 100644
--- a/python/samba/tests/dns.py
+++ b/python/samba/tests/dns.py
@@ -534,6 +534,123 @@ class TestDNSUpdates(DNSTest):
         response = self.dns_transaction_udp(p)
         self.assert_dns_rcode_equals(response, dns.DNS_RCODE_NXDOMAIN)
 
+    def test_readd_record(self):
+        "Test if adding, deleting and then readding a records works"
+
+        NAME = "readdrec.%s" % self.get_dns_domain()
+
+        # Create the record
+        p = self.make_name_packet(dns.DNS_OPCODE_UPDATE)
+        updates = []
+
+        name = self.get_dns_domain()
+
+        u = self.make_name_question(name, dns.DNS_QTYPE_SOA, dns.DNS_QCLASS_IN)
+        updates.append(u)
+        self.finish_name_packet(p, updates)
+
+        updates = []
+        r = dns.res_rec()
+        r.name = NAME
+        r.rr_type = dns.DNS_QTYPE_TXT
+        r.rr_class = dns.DNS_QCLASS_IN
+        r.ttl = 900
+        r.length = 0xffff
+        rdata = dns.txt_record()
+        rdata.txt = '"This is a test"'
+        r.rdata = rdata
+        updates.append(r)
+        p.nscount = len(updates)
+        p.nsrecs = updates
+
+        response = self.dns_transaction_udp(p)
+        self.assert_dns_rcode_equals(response, dns.DNS_RCODE_OK)
+
+        # Now check the record is around
+        p = self.make_name_packet(dns.DNS_OPCODE_QUERY)
+        questions = []
+        q = self.make_name_question(NAME, dns.DNS_QTYPE_TXT, dns.DNS_QCLASS_IN)
+        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)
+
+        # Now delete the record
+        p = self.make_name_packet(dns.DNS_OPCODE_UPDATE)
+        updates = []
+
+        name = self.get_dns_domain()
+
+        u = self.make_name_question(name, dns.DNS_QTYPE_SOA, dns.DNS_QCLASS_IN)
+        updates.append(u)
+        self.finish_name_packet(p, updates)
+
+        updates = []
+        r = dns.res_rec()
+        r.name = NAME
+        r.rr_type = dns.DNS_QTYPE_TXT
+        r.rr_class = dns.DNS_QCLASS_NONE
+        r.ttl = 0
+        r.length = 0xffff
+        rdata = dns.txt_record()
+        rdata.txt = '"This is a test"'
+        r.rdata = rdata
+        updates.append(r)
+        p.nscount = len(updates)
+        p.nsrecs = updates
+
+        response = self.dns_transaction_udp(p)
+        self.assert_dns_rcode_equals(response, dns.DNS_RCODE_OK)
+
+        # check it's gone
+        p = self.make_name_packet(dns.DNS_OPCODE_QUERY)
+        questions = []
+
+        q = self.make_name_question(NAME, dns.DNS_QTYPE_TXT, dns.DNS_QCLASS_IN)
+        questions.append(q)
+
+        self.finish_name_packet(p, questions)
+        response = self.dns_transaction_udp(p)
+        self.assert_dns_rcode_equals(response, dns.DNS_RCODE_NXDOMAIN)
+
+        # recreate the record
+        p = self.make_name_packet(dns.DNS_OPCODE_UPDATE)
+        updates = []
+
+        name = self.get_dns_domain()
+
+        u = self.make_name_question(name, dns.DNS_QTYPE_SOA, dns.DNS_QCLASS_IN)
+        updates.append(u)
+        self.finish_name_packet(p, updates)
+
+        updates = []
+        r = dns.res_rec()
+        r.name = NAME
+        r.rr_type = dns.DNS_QTYPE_TXT
+        r.rr_class = dns.DNS_QCLASS_IN
+        r.ttl = 900
+        r.length = 0xffff
+        rdata = dns.txt_record()
+        rdata.txt = '"This is a test"'
+        r.rdata = rdata
+        updates.append(r)
+        p.nscount = len(updates)
+        p.nsrecs = updates
+
+        response = self.dns_transaction_udp(p)
+        self.assert_dns_rcode_equals(response, dns.DNS_RCODE_OK)
+
+        # Now check the record is around
+        p = self.make_name_packet(dns.DNS_OPCODE_QUERY)
+        questions = []
+        q = self.make_name_question(NAME, dns.DNS_QTYPE_TXT, dns.DNS_QCLASS_IN)
+        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)
+
     def test_update_add_mx_record(self):
         "test adding MX records works"
         p = self.make_name_packet(dns.DNS_OPCODE_UPDATE)
diff --git a/source4/dns_server/dns_utils.c b/source4/dns_server/dns_utils.c
index 21c7f5a680..72782cf450 100644
--- a/source4/dns_server/dns_utils.c
+++ b/source4/dns_server/dns_utils.c
@@ -276,7 +276,13 @@ WERROR dns_replace_records(struct dns_server *dns,
 		if (needs_add) {
 			return WERR_OK;
 		}
-		/* TODO: Delete object? */
+		/* No entries left, delete the dnsNode object */
+		ret = ldb_delete(dns->samdb, msg->dn);
+		if (ret != LDB_SUCCESS) {
+			DEBUG(0, ("Deleting record failed; %d\n", ret));
+			return DNS_ERR(SERVER_FAILURE);
+		}
+		return WERR_OK;
 	}
 
 	if (needs_add) {