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s4 dns: Correctly handle A questions for CNAMEs

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When an A/AAAA lookup is made for a name that actually is a CNAME
record, we need to return the CNAME record, and then do the A/AAAA
lookup for the name the CNAME points at.

This still fails for CNAMEs pointing at records for domains we need to
ask our forwarders for.

Autobuild-User: Kai Blin <kai@samba.org>
Autobuild-Date: Wed Jun  6 15:23:55 CEST 2012 on sn-devel-104
This commit is contained in:
Kai Blin
2012-06-01 08:05:54 +02:00
parent 754c60e417
commit f3df2988ba
2 changed files with 132 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
source4/dns_server/dns_query.c
View File

@ -231,11 +231,11 @@ static WERROR handle_question(struct dns_server *dns,
const struct dns_name_question *question,
struct dns_res_rec **answers, uint16_t *ancount)
{
struct dns_res_rec *ans;
struct dns_res_rec *ans = *answers;
WERROR werror;
unsigned int ri;
struct dnsp_DnssrvRpcRecord *recs;
uint16_t rec_count, ai = 0;
uint16_t rec_count, ai = *ancount;
struct ldb_dn *dn = NULL;
werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
@ -244,16 +244,67 @@ static WERROR handle_question(struct dns_server *dns,
werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
W_ERROR_NOT_OK_RETURN(werror);
ans = talloc_zero_array(mem_ctx, struct dns_res_rec, rec_count);
W_ERROR_HAVE_NO_MEMORY(ans);
ans = talloc_realloc(mem_ctx, ans, struct dns_res_rec, rec_count + ai);
if (ans == NULL) {
return WERR_NOMEM;
}
for (ri = 0; ri < rec_count; ri++) {
if ((recs[ri].wType == DNS_TYPE_CNAME) &&
((question->question_type == DNS_QTYPE_A) ||
(question->question_type == DNS_QTYPE_AAAA))) {
struct dns_name_question *new_q =
talloc(mem_ctx, struct dns_name_question);
if (new_q == NULL) {
return WERR_NOMEM;
}
/* We reply with one more record, so grow the array */
ans = talloc_realloc(mem_ctx, ans, struct dns_res_rec,
rec_count + 1);
if (ans == NULL) {
TALLOC_FREE(new_q);
return WERR_NOMEM;
}
/* First put in the CNAME record */
werror = create_response_rr(question, &recs[ri], &ans, &ai);
if (!W_ERROR_IS_OK(werror)) {
return werror;
}
/* And then look up the name it points at.. */
/* First build up the new question */
new_q->question_type = question->question_type;
new_q->question_class = question->question_class;
if (new_q->question_type == DNS_QTYPE_A) {
new_q->name = talloc_strdup(new_q, recs[ri].data.ipv4);
} else if (new_q->question_type == DNS_QTYPE_AAAA) {
new_q->name = talloc_strdup(new_q, recs[ri].data.ipv6);
}
if (new_q->name == NULL) {
TALLOC_FREE(new_q);
return WERR_NOMEM;
}
/* and then call the lookup again */
werror = handle_question(dns, mem_ctx, new_q, &ans, &ai);
if (!W_ERROR_IS_OK(werror)) {
return werror;
}
continue;
}
if ((question->question_type != DNS_QTYPE_ALL) &&
(recs[ri].wType != question->question_type)) {
continue;
}
werror = create_response_rr(question, &recs[ri], &ans, &ai);
W_ERROR_NOT_OK_RETURN(werror);
if (!W_ERROR_IS_OK(werror)) {
return werror;
}
}
if (ai == 0) {

76
source4/scripting/python/samba/tests/dns.py
View File

@ -469,6 +469,82 @@ class TestDNSUpdates(DNSTest):
self.assert_dns_rcode_equals(response, dns.DNS_RCODE_NXDOMAIN)
class TestComplexQueries(DNSTest):
def setUp(self):
super(TestComplexQueries, self).setUp()
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 = "cname_test.%s" % self.get_dns_domain()
r.rr_type = dns.DNS_QTYPE_CNAME
r.rr_class = dns.DNS_QCLASS_IN
r.ttl = 900
r.length = 0xffff
r.rdata = "%s.%s" % (os.getenv('DC_SERVER'), self.get_dns_domain())
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)
def tearDown(self):
super(TestComplexQueries, self).tearDown()
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 = "cname_test.%s" % self.get_dns_domain()
r.rr_type = dns.DNS_QTYPE_CNAME
r.rr_class = dns.DNS_QCLASS_NONE
r.ttl = 0
r.length = 0xffff
r.rdata = "%s.%s" % (os.getenv('DC_SERVER'), self.get_dns_domain())
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)
def test_one_a_query(self):
"create a query packet containing one query record"
p = self.make_name_packet(dns.DNS_OPCODE_QUERY)
questions = []
name = "cname_test.%s" % self.get_dns_domain()
q = self.make_name_question(name, dns.DNS_QTYPE_A, 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, 2)
self.assertEquals(response.answers[0].rr_type, dns.DNS_QTYPE_CNAME)
self.assertEquals(response.answers[0].rdata, "%s.%s" %
(os.getenv('DC_SERVER'), self.get_dns_domain()))
self.assertEquals(response.answers[1].rr_type, dns.DNS_QTYPE_A)
self.assertEquals(response.answers[1].rdata,
os.getenv('DC_SERVER_IP'))
if __name__ == "__main__":
import unittest
unittest.main()