feature: add expand ptr from address feature

etc/smartdns/smartdns.conf

@@ -236,6 +236,9 @@ log-level info
 # nameserver /www.example.com/office, Set the domain name to use the appropriate server group.
 # nameserver /www.example.com/-, ignore this domain
 
+# expand ptr record from address record
+# expand-ptr-from-address yes
+
 # specific address to domain
 # address /domain/[ip|-|-4|-6|#|#4|#6]
 # address /www.example.com/1.2.3.4, return ip 1.2.3.4 to client

src/dns_conf.c

@@ -140,6 +140,8 @@ int dns_conf_dualstack_ip_selection = 1;
 int dns_conf_dualstack_ip_allow_force_AAAA;
 int dns_conf_dualstack_ip_selection_threshold = 10;
 
+int dns_conf_expand_ptr_from_address = 0;
+
 /* TTL */
 int dns_conf_rr_ttl;
 int dns_conf_rr_ttl_reply_max;
@@ -167,6 +169,7 @@ struct dns_edns_client_subnet dns_conf_ipv6_ecs;
 char dns_conf_sni_proxy_ip[DNS_MAX_IPLEN];
 
 static int _conf_domain_rule_nameserver(char *domain, const char *group_name);
+static int _conf_ptr_add(const char *hostname, const char *ip, int is_dynamic);
 
 static void *_new_dns_rule(enum domain_rule domain_rule)
 {
@@ -1575,6 +1578,11 @@ static int _conf_domain_rule_address(char *domain, const char *domain_address)
 		default:
 			goto errout;
 		}
+
+		/* add PTR */
+		if (dns_conf_expand_ptr_from_address == 1 && _conf_ptr_add(domain, ip, 0) != 0) {
+			goto errout;
+		}
 	}
 
 	/* add domain to ART-tree */
@@ -2790,6 +2798,7 @@ static struct dns_ptr *_dns_conf_get_ptr(const char *ptr_domain)
 
 	safe_strncpy(ptr->ptr_domain, ptr_domain, DNS_MAX_PTR_LEN);
 	hash_add(dns_ptr_table.ptr, &ptr->node, key);
+	ptr->is_soa = 1;
 
 	return ptr;
 errout:
@@ -2800,7 +2809,7 @@ errout:
 	return NULL;
 }
 
-static int _conf_ptr_add(const char *hostname, const char *ip)
+static int _conf_ptr_add(const char *hostname, const char *ip, int is_dynamic)
 {
 	struct dns_ptr *ptr = NULL;
 	struct sockaddr_storage addr;
@@ -2852,6 +2861,13 @@ static int _conf_ptr_add(const char *hostname, const char *ip)
 		goto errout;
 	}
 
+	if (is_dynamic == 1 && ptr->is_soa == 0 && ptr->is_dynamic == 0) {
+		/* already set fix PTR, skip */
+		return 0;
+	}
+
+	ptr->is_dynamic = is_dynamic;
+	ptr->is_soa = 0;
 	safe_strncpy(ptr->hostname, hostname, DNS_MAX_CNAME_LEN);
 
 	return 0;
@@ -2860,7 +2876,7 @@ errout:
 	return -1;
 }
 
-static void _config_ptr_table_destroy(void)
+static void _config_ptr_table_destroy(int only_dynamic)
 {
 	struct dns_ptr *ptr = NULL;
 	struct hlist_node *tmp = NULL;
@@ -2868,6 +2884,10 @@ static void _config_ptr_table_destroy(void)
 
 	hash_for_each_safe(dns_ptr_table.ptr, i, tmp, ptr, node)
 	{
+		if (only_dynamic != 0 && ptr->is_dynamic == 0) {
+			continue;
+		}
+
 		hlist_del_init(&ptr->node);
 		free(ptr);
 	}
@@ -2912,7 +2932,7 @@ errout:
 	return NULL;
 }
 
-static int _conf_host_add(const char *hostname, const char *ip, dns_hosts_type host_type)
+static int _conf_host_add(const char *hostname, const char *ip, dns_hosts_type host_type, int is_dynamic)
 {
 	struct dns_hosts *host = NULL;
 	struct dns_hosts *host_other __attribute__((unused));
@@ -2952,9 +2972,14 @@ static int _conf_host_add(const char *hostname, const char *ip, dns_hosts_type h
 		goto errout;
 	}
 
+	if (is_dynamic == 1 && host->is_soa == 0 && host->is_dynamic == 0) {
+		/* already set fixed PTR, skip */
+		return 0;
+	}
+
 	/* add this to return SOA when addr is not exist */
 	host_other = _dns_conf_get_hosts(hostname, dns_type_other);
-
+	host->is_dynamic = is_dynamic;
 	host->host_type = host_type;
 
 	switch (addr.ss_family) {
@@ -3013,12 +3038,12 @@ static int _conf_dhcp_lease_dnsmasq_add(const char *file)
 			continue;
 		}
 
-		ret = _conf_host_add(hostname, ip, DNS_HOST_TYPE_DNSMASQ);
+		ret = _conf_host_add(hostname, ip, DNS_HOST_TYPE_DNSMASQ, 1);
 		if (ret != 0) {
 			tlog(TLOG_WARN, "add host %s/%s at %d failed", hostname, ip, line_no);
 		}
 
-		ret = _conf_ptr_add(hostname, ip);
+		ret = _conf_ptr_add(hostname, ip, 1);
 		if (ret != 0) {
 			tlog(TLOG_WARN, "add ptr %s/%s at %d failed.", hostname, ip, line_no);
 		}
@@ -3055,7 +3080,7 @@ static int _conf_hosts_file(void *data, int argc, char *argv[])
 	return 0;
 }
 
-static void _config_host_table_destroy(void)
+static void _config_host_table_destroy(int only_dynamic)
 {
 	struct dns_hosts *host = NULL;
 	struct hlist_node *tmp = NULL;
@@ -3063,6 +3088,10 @@ static void _config_host_table_destroy(void)
 
 	hash_for_each_safe(dns_hosts_table.hosts, i, tmp, host, node)
 	{
+		if (only_dynamic != 0 && host->is_dynamic == 0) {
+			continue;
+		}
+
 		hlist_del_init(&host->node);
 		free(host);
 	}
@@ -3093,8 +3122,8 @@ int dns_server_check_update_hosts(void)
 		return -1;
 	}
 
-	_config_ptr_table_destroy();
-	_config_host_table_destroy();
+	_config_ptr_table_destroy(1);
+	_config_host_table_destroy(1);
 
 	if (_conf_dhcp_lease_dnsmasq_add(dns_conf_dnsmasq_lease_file) != 0) {
 		return -1;
@@ -3187,6 +3216,7 @@ static struct config_item _config_item[] = {
 	CONF_CUSTOM("server-tls", _config_server_tls, NULL),
 	CONF_CUSTOM("server-https", _config_server_https, NULL),
 	CONF_CUSTOM("nameserver", _config_nameserver, NULL),
+	CONF_YESNO("expand-ptr-from-address", &dns_conf_expand_ptr_from_address),
 	CONF_CUSTOM("address", _config_address, NULL),
 	CONF_CUSTOM("cname", _config_cname, NULL),
 	CONF_CUSTOM("proxy-server", _config_proxy_server, NULL),
@@ -3336,8 +3366,8 @@ void dns_server_load_exit(void)
 	_config_ipset_table_destroy();
 	_config_nftset_table_destroy();
 	_config_group_table_destroy();
-	_config_ptr_table_destroy();
-	_config_host_table_destroy();
+	_config_ptr_table_destroy(0);
+	_config_host_table_destroy(0);
 	_config_qtype_soa_table_destroy();
 	_config_proxy_table_destroy();
 

src/dns_conf.h

@@ -249,6 +249,8 @@ struct dns_ptr {
 	struct hlist_node node;
 	char ptr_domain[DNS_MAX_PTR_LEN];
 	char hostname[DNS_MAX_CNAME_LEN];
+	char is_dynamic;
+	char is_soa;
 };
 
 struct dns_ptr_table {
@@ -266,7 +268,8 @@ struct dns_hosts {
 	char domain[DNS_MAX_CNAME_LEN];
 	dns_hosts_type host_type;
 	int dns_type;
-	int is_soa;
+	char is_soa;
+	char is_dynamic;
 	union {
 		unsigned char ipv4_addr[DNS_RR_A_LEN];
 		unsigned char ipv6_addr[DNS_RR_AAAA_LEN];

test/cases/test-address.cc

@@ -161,3 +161,50 @@ cache-persist no)""");
 	EXPECT_EQ(client.GetAnswer()[0].GetType(), "AAAA");
 	EXPECT_EQ(client.GetAnswer()[0].GetData(), "64:ff9b::1010:1010");
 }
+
+TEST_F(Address, ptr)
+{
+	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) {
+			smartdns::MockServer::AddIP(request, request->domain.c_str(), "1.2.3.4", 700);
+			return smartdns::SERVER_REQUEST_OK;
+		} else if (request->qtype == DNS_T_AAAA) {
+			smartdns::MockServer::AddIP(request, request->domain.c_str(), "64:ff9b::102:304", 700);
+			return smartdns::SERVER_REQUEST_OK;
+		}
+		return smartdns::SERVER_REQUEST_SOA;
+	});
+
+	server.Start(R"""(bind [::]:60053
+server 127.0.0.1:61053
+log-num 0
+log-console yes
+log-level debug
+speed-check-mode none
+expand-ptr-from-address yes
+address /a.com/10.11.12.13
+address /a.com/64:ff9b::1010:1010
+cache-persist no)""");
+	smartdns::Client client;
+	ASSERT_TRUE(client.Query("13.12.11.10.in-addr.arpa PTR", 60053));
+	std::cout << client.GetResult() << std::endl;
+	ASSERT_EQ(client.GetAnswerNum(), 1);
+	EXPECT_EQ(client.GetStatus(), "NOERROR");
+	EXPECT_EQ(client.GetAnswer()[0].GetName(), "13.12.11.10.in-addr.arpa");
+	EXPECT_EQ(client.GetAnswer()[0].GetTTL(), 600);
+	EXPECT_EQ(client.GetAnswer()[0].GetType(), "PTR");
+	EXPECT_EQ(client.GetAnswer()[0].GetData(), "a.com.");
+
+	ASSERT_TRUE(client.Query("0.1.0.1.0.1.0.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.b.9.f.f.4.6.0.0.ip6.arpa PTR", 60053));
+	std::cout << client.GetResult() << std::endl;
+	ASSERT_EQ(client.GetAnswerNum(), 1);
+	EXPECT_EQ(client.GetStatus(), "NOERROR");
+	EXPECT_EQ(client.GetAnswer()[0].GetName(),
+			  "0.1.0.1.0.1.0.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.b.9.f.f.4.6.0.0.ip6.arpa");
+	EXPECT_EQ(client.GetAnswer()[0].GetTTL(), 600);
+	EXPECT_EQ(client.GetAnswer()[0].GetType(), "PTR");
+	EXPECT_EQ(client.GetAnswer()[0].GetData(), "a.com.");
+}

test/client.cc

@@ -49,7 +49,18 @@ DNSRecord::~DNSRecord() {}
 
 bool DNSRecord::Parser(const std::string &line)
 {
-	std::vector<std::string> fields = StringSplit(line, '\t');
+	std::vector<std::string> fields_first = StringSplit(line, '\t');
+	std::vector<std::string> fields;
+
+	for (const auto &f : fields_first) {
+		std::vector<std::string> fields_second = StringSplit(f, ' ');
+		for (const auto &s : fields_second) {
+			if (s.length() > 0) {
+				fields.push_back(s);
+			}
+		}
+	}
+
 	if (fields.size() < 3) {
 		std::cerr << "Invalid DNS record: " << line << ", size: " << fields.size() << std::endl;
 		return false;