[PATCH] dns: Delete dnsNode objects when they are empty

[Kai Blin]

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 at samba.org>
---
 python/samba/tests/dns.py      | 117 +++++++++++++++++++++++++++++++++++++++++
 source4/dns_server/dns_utils.c |   8 ++-
 2 files changed, 124 insertions(+), 1 deletion(-)

diff --git a/python/samba/tests/dns.py b/python/samba/tests/dns.py
index 15672a0..0ac9cf4 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 21c7f5a..72782cf 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) {
-- 
1.8.1.2