cname: fix cname rule loop issue.

src/dns_client.c

@@ -2297,7 +2297,7 @@ static int _dns_client_process_udp(struct dns_server_info *server_info, struct e
 			return 0;
 		}
 
-		if (errno == ECONNREFUSED) {
+		if (errno == ECONNREFUSED || errno == ENETUNREACH || errno == EHOSTUNREACH) {
 			tlog(TLOG_DEBUG, "recvfrom %s failed, %s\n", server_info->ip, strerror(errno));
 			goto errout;
 		}
@@ -3568,7 +3568,7 @@ static int _dns_client_send_packet(struct dns_query_struct *query, void *packet,
 		time(&now);
 		if (now - lastlog > 120) {
 			lastlog = now;
-			tlog(TLOG_WARN, "Send query %s to upstream server failed, total server number %d", query->domain,
+			tlog(TLOG_WARN, "send query %s to upstream server failed, total server number %d", query->domain,
 				 total_server);
 		}
 		return -1;

src/dns_server.c

@@ -311,6 +311,8 @@ struct dns_request {
 	int no_select_possible_ip;
 	int no_cache_cname;
 	int no_cache;
+
+	int has_cname_loop;
 };
 
 /* dns server data */
@@ -4228,6 +4230,10 @@ static int _dns_server_process_cname_pre(struct dns_request *request)
 		return 0;
 	}
 
+	if (request->has_cname_loop == 1) {
+		return 0;
+	}
+
 	/* get domain rule flag */
 	rule_flag = _dns_server_get_dns_rule(request, DOMAIN_RULE_FLAGS);
 	if (rule_flag != NULL) {
@@ -4267,6 +4273,10 @@ static int _dns_server_process_cname(struct dns_request *request)
 		return 0;
 	}
 
+	if (request->has_cname_loop == 1) {
+		return 0;
+	}
+
 	/* get domain rule flag */
 	rule_flag = _dns_server_get_dns_rule(request, DOMAIN_RULE_FLAGS);
 	if (rule_flag != NULL) {
@@ -4289,6 +4299,33 @@ static int _dns_server_process_cname(struct dns_request *request)
 		return -1;
 	}
 
+	/* check cname rule loop */
+	struct dns_request *check_request = child_request->parent_request;
+	struct dns_cname_rule *child_cname = _dns_server_get_dns_rule(child_request, DOMAIN_RULE_CNAME);
+
+	/* sub domain rule*/
+	if (child_cname != NULL && strncmp(child_request->domain, child_cname->cname, DNS_MAX_CNAME_LEN) == 0) {
+		child_request->domain_rule.rules[DOMAIN_RULE_CNAME] = NULL;
+		child_request->has_cname_loop = 1;
+	}
+
+	/* loop rule */
+	while (check_request != NULL && child_cname != NULL) {
+		struct dns_cname_rule *check_cname = _dns_server_get_dns_rule(check_request, DOMAIN_RULE_CNAME);
+		if (check_cname == NULL) {
+			break;
+		}
+
+		if (strstr(child_request->domain, check_request->domain) != NULL &&
+			check_request != child_request->parent_request) {
+			child_request->domain_rule.rules[DOMAIN_RULE_CNAME] = NULL;
+			child_request->has_cname_loop = 1;
+			break;
+		}
+
+		check_request = check_request->parent_request;
+	}
+
 	child_group_name = _dns_server_get_request_groupname(child_request);
 	if (child_group_name) {
 		/* reset dns group and setup child request domain group again when do query.*/
@@ -5029,6 +5066,7 @@ static int _dns_server_query_dualstack(struct dns_request *request)
 	safe_strncpy(request_dualstack->domain, request->domain, sizeof(request->domain));
 	request_dualstack->qtype = qtype;
 	request_dualstack->dualstack_selection_query = 1;
+	request_dualstack->has_cname_loop = request->has_cname_loop;
 	request_dualstack->prefetch = request->prefetch;
 	request_dualstack->prefetch_expired_domain = request->prefetch_expired_domain;
 	_dns_server_request_get(request);

test/cases/test-cname.cc

@@ -63,3 +63,117 @@ cache-persist no)""");
 	EXPECT_EQ(client.GetAnswer()[0].GetData(), "b.com.");
 	EXPECT_EQ(client.GetAnswer()[1].GetData(), "1.2.3.4");
 }
+
+TEST_F(Cname, subdomain1)
+{
+	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
+log-num 0
+log-console yes
+log-level debug
+cache-persist no)""");
+	smartdns::Client client;
+	ASSERT_TRUE(client.Query("a.com", 60053));
+	std::cout << client.GetResult() << std::endl;
+	ASSERT_EQ(client.GetAnswerNum(), 2);
+	EXPECT_EQ(client.GetStatus(), "NOERROR");
+	EXPECT_EQ(client.GetAnswer()[0].GetName(), "a.com");
+	EXPECT_EQ(client.GetAnswer()[0].GetData(), "s.a.com.");
+	EXPECT_EQ(client.GetAnswer()[1].GetData(), "4.5.6.7");
+}
+
+TEST_F(Cname, subdomain2)
+{
+	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 == "a.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
+cname /s.a.com/a.s.a.com
+server 127.0.0.1:61053
+log-num 0
+log-console yes
+log-level debug
+cache-persist no)""");
+	smartdns::Client client;
+	ASSERT_TRUE(client.Query("a.com", 60053));
+	std::cout << client.GetResult() << std::endl;
+	ASSERT_EQ(client.GetAnswerNum(), 2);
+	EXPECT_EQ(client.GetStatus(), "NOERROR");
+	EXPECT_EQ(client.GetAnswer()[0].GetName(), "a.com");
+	EXPECT_EQ(client.GetAnswer()[0].GetData(), "s.a.com.");
+	EXPECT_EQ(client.GetAnswer()[1].GetData(), "4.5.6.7");
+}
+
+
+TEST_F(Cname, loop)
+{
+	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/c.a.com
+cname /c.a.com/s.a.com
+server 127.0.0.1:61053
+log-num 0
+log-console yes
+log-level debug
+cache-persist no)""");
+	smartdns::Client client;
+	ASSERT_TRUE(client.Query("a.com", 60053));
+	std::cout << client.GetResult() << std::endl;
+	ASSERT_EQ(client.GetAnswerNum(), 2);
+	EXPECT_EQ(client.GetStatus(), "NOERROR");
+	EXPECT_EQ(client.GetAnswer()[0].GetName(), "a.com");
+	EXPECT_EQ(client.GetAnswer()[0].GetData(), "c.a.com.");
+	EXPECT_EQ(client.GetAnswer()[1].GetData(), "4.5.6.7");
+}