dns_server: fix cname loop issue.

Author: pymumu

src/dns_server.c

@@ -5957,6 +5957,14 @@ static int _dns_server_process_cname(struct dns_request *request)
 		check_request = check_request->parent_request;
 	}
 
+	/* query cname domain  */
+	if (child_request->has_cname_loop == 1 && strncasecmp(request->domain, cname->cname, DNS_MAX_CNAME_LEN) == 0) {
+		request->has_cname_loop = 0;
+		request->domain_rule.rules[DOMAIN_RULE_CNAME] = NULL;
+		tlog(TLOG_DEBUG, "query cname domain %s", request->domain);
+		goto out;
+	}
+
 	child_group_name = _dns_server_get_request_server_groupname(child_request);
 	if (child_group_name) {
 		/* reset dns group and setup child request domain group again when do query.*/
@@ -5975,13 +5983,21 @@ static int _dns_server_process_cname(struct dns_request *request)
 	return 1;
 
 errout:
-
 	if (child_request) {
 		request->child_request = NULL;
 		_dns_server_request_release(child_request);
 	}
 
 	return -1;
+
+out:
+	if (child_request) {
+		child_request->parent_request = NULL;
+		request->child_request = NULL;
+		_dns_server_request_release(child_request);
+		_dns_server_request_release(request);
+	}
+	return 0;
 }
 
 static enum DNS_CHILD_POST_RESULT

test/cases/test-cname.cc

@@ -161,3 +161,35 @@ server 127.0.0.1:61053
 	EXPECT_EQ(client.GetAnswer()[0].GetData(), "c.a.com.");
 	EXPECT_EQ(client.GetAnswer()[1].GetData(), "4.5.6.7");
 }
+
+TEST_F(Cname, query_cname)
+{
+	smartdns::MockServer server_upstream;
+	smartdns::Server server;
+
+	server_upstream.Start("udp://0.0.0.0:61053", [](struct smartdns::ServerRequestContext *request) {
+		if (request->qtype != DNS_T_A) {
+			return smartdns::SERVER_REQUEST_SOA;
+		}
+
+		if (request->domain == "s.a.com") {
+			smartdns::MockServer::AddIP(request, request->domain.c_str(), "4.5.6.7", 700);
+			return smartdns::SERVER_REQUEST_OK;
+		}
+
+		smartdns::MockServer::AddIP(request, request->domain.c_str(), "1.2.3.4", 611);
+		return smartdns::SERVER_REQUEST_OK;
+	});
+
+	server.Start(R"""(bind [::]:60053
+cname /a.com/s.a.com
+server 127.0.0.1:61053
+)""");
+	smartdns::Client client;
+	ASSERT_TRUE(client.Query("s.a.com", 60053));
+	std::cout << client.GetResult() << std::endl;
+	ASSERT_EQ(client.GetAnswerNum(), 1);
+	EXPECT_EQ(client.GetStatus(), "NOERROR");
+	EXPECT_EQ(client.GetAnswer()[0].GetName(), "s.a.com");
+	EXPECT_EQ(client.GetAnswer()[0].GetData(), "4.5.6.7");
+}