feature: support lookup local network host name or ip via mDNS

etc/smartdns/smartdns.conf

@@ -199,7 +199,7 @@ log-level info
 #   g|-group [group]: set server to group, use with nameserver /domain/group.
 #   e|-exclude-default-group: exclude this server from default group.
 #   p|-proxy [proxy-name]: use proxy to connect to server.
-#   -bootstrap-dns: set as bootstrap dns server.
+#   b|-bootstrap-dns: set as bootstrap dns server.
 #   -set-mark: set mark on packets.
 #   -subnet [ip/subnet]: set edns client subnet.
 #   -host-ip [ip]: set dns server host ip.
@@ -307,6 +307,10 @@ log-level info
 # set ddns domain
 # ddns-domain domain
 
+# lookup local network hostname or ip address from mdns
+# mdns-lookup [yes|no]
+# mdns-lookup no
+
 # set domain rules
 # domain-rules /domain/ [-speed-check-mode [...]]
 # rules:

package/luci-compat/files/luci/i18n/smartdns.zh-cn.po

@@ -350,6 +350,9 @@ msgstr "日志数量"
 msgid "Log File"
 msgstr "日志文件路径"
 
+msgid "mDNS Lookup"
+msgstr "mDNS查询"
+
 msgid "Marking Packets"
 msgstr "数据包标记"
 
@@ -434,6 +437,9 @@ msgstr "解析本地主机名"
 msgid "Resolve local hostnames by reading Dnsmasq lease file."
 msgstr "读取Dnsmasq的租约文件解析本地主机名。"
 
+msgid "Resolve local network hostname via mDNS protocol."
+msgstr "使用mDNS协议解析本地网络主机名。"
+
 msgid "Response Mode"
 msgstr "响应模式"
 

package/luci-compat/files/luci/model/cbi/smartdns/smartdns.lua

@@ -239,7 +239,7 @@ o.cfgvalue    = function(...)
     return Flag.cfgvalue(...) or "1"
 end
 
--- cache-size
+-- resolve local hostname
 o = s:taboption("advanced", Flag, "resolve_local_hostnames", translate("Resolve Local Hostnames"), translate("Resolve local hostnames by reading Dnsmasq lease file."))
 o.rmempty     = false
 o.default     = o.enabled
@@ -247,6 +247,14 @@ o.cfgvalue    = function(...)
     return Flag.cfgvalue(...) or "1"
 end
 
+-- resolve local network hostname via mDNS
+o = s:taboption("advanced", Flag, "mdns_lookup", translate("mDNS Lookup"), translate("Resolve local network hostname via mDNS protocol."))
+o.rmempty     = true
+o.default     = o.disabled
+o.cfgvalue    = function(...)
+    return Flag.cfgvalue(...) or "0"
+end
+
 -- Force AAAA SOA
 o = s:taboption("advanced", Flag, "force_aaaa_soa", translate("Force AAAA SOA"), translate("Force AAAA SOA."))
 o.rmempty     = true

package/luci/files/luci/i18n/smartdns.zh-cn.po

@@ -393,6 +393,9 @@ msgstr "日志数量"
 msgid "Log File"
 msgstr "日志文件路径"
 
+msgid "mDNS Lookup"
+msgstr "mDNS查询"
+
 msgid "Marking Packets"
 msgstr "数据包标记"
 
@@ -483,6 +486,9 @@ msgstr "解析本地主机名"
 msgid "Resolve local hostnames by reading Dnsmasq lease file."
 msgstr "读取Dnsmasq的租约文件解析本地主机名。"
 
+msgid "Resolve local network hostname via mDNS protocol."
+msgstr "使用mDNS协议解析本地网络主机名。"
+
 msgid "Response Mode"
 msgstr "响应模式"
 

package/luci/files/root/www/luci-static/resources/view/smartdns/smartdns.js

@@ -311,11 +311,16 @@ return view.extend({
 		o.rmempty = false;
 		o.default = o.enabled;
 
-		// cache-size;
+		// resolve local hostname;
 		o = s.taboption("advanced", form.Flag, "resolve_local_hostnames", _("Resolve Local Hostnames"), _("Resolve local hostnames by reading Dnsmasq lease file."));
 		o.rmempty = false;
 		o.default = o.enabled;
 
+		// resolve local network hostname via mDNS;
+		o = s.taboption("advanced", form.Flag, "mdns_lookup", _("mDNS Lookup"), _("Resolve local network hostname via mDNS protocol."));
+		o.rmempty = true;
+		o.default = o.disabled;
+
 		// Force AAAA SOA
 		o = s.taboption("advanced", form.Flag, "force_aaaa_soa", _("Force AAAA SOA"), _("Force AAAA SOA."));
 		o.rmempty = true;

package/openwrt/files/etc/init.d/smartdns

@@ -644,6 +644,9 @@ load_service()
 	config_get dns64 "$section" "dns64" ""
 	[ -z "$dns64" ] || conf_append "dns64" "$dns64"
 
+	config_get_bool mdns_lookup "$section" "mdns_lookup" "0"
+	[ "$mdns_lookup" = "1" ] && conf_append "mdns-lookup" "yes"
+
 	config_get redirect "$section" "redirect" ""
 	config_get old_port "$section" "old_port" "0"
 	config_get old_enabled "$section" "old_enabled" "0"

src/dns_client.c

@@ -33,7 +33,9 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <ifaddrs.h>
 #include <linux/filter.h>
+#include <net/if.h>
 #include <netdb.h>
 #include <netinet/icmp6.h>
 #include <netinet/ip.h>
@@ -50,6 +52,7 @@
 #include <string.h>
 #include <sys/epoll.h>
 #include <sys/eventfd.h>
+#include <sys/ioctl.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -67,6 +70,9 @@
 #define SOCKET_PRIORITY (6)
 #define SOCKET_IP_TOS (IPTOS_LOWDELAY | IPTOS_RELIABILITY)
 
+#define DNS_MDNS_IP "224.0.0.251"
+#define DNS_MDNS_PORT 5353
+
 /* ECS info */
 struct dns_client_ecs {
 	int enable;
@@ -400,6 +406,42 @@ int dns_client_get_server_port(struct dns_server_info *server_info)
 	return server_info->port;
 }
 
+static inline void _dns_server_inc_server_num(struct dns_server_info *server_info)
+{
+	if (server_info->type == DNS_SERVER_MDNS) {
+		return;
+	}
+
+	atomic_inc(&client.dns_server_num);
+}
+
+static inline void _dns_server_dec_server_num(struct dns_server_info *server_info)
+{
+	if (server_info->type == DNS_SERVER_MDNS) {
+		return;
+	}
+
+	atomic_dec(&client.dns_server_num);
+}
+
+static inline void _dns_server_inc_prohibit_server_num(struct dns_server_info *server_info)
+{
+	if (server_info->type == DNS_SERVER_MDNS) {
+		return;
+	}
+
+	atomic_inc(&client.dns_server_prohibit_num);
+}
+
+static inline void _dns_server_dec_prohibit_server_num(struct dns_server_info *server_info)
+{
+	if (server_info->type == DNS_SERVER_MDNS) {
+		return;
+	}
+
+	atomic_dec(&client.dns_server_prohibit_num);
+}
+
 dns_server_type_t dns_client_get_server_type(struct dns_server_info *server_info)
 {
 	if (server_info == NULL) {
@@ -426,6 +468,9 @@ static const char *_dns_server_get_type_string(dns_server_type_t type)
 	case DNS_SERVER_HTTPS:
 		type_str = "https";
 		break;
+	case DNS_SERVER_MDNS:
+		type_str = "mdns";
+		break;
 	default:
 		break;
 	}
@@ -760,8 +805,7 @@ int dns_client_add_group(const char *group_name)
 	}
 
 	if (_dns_client_get_group(group_name) != NULL) {
-		tlog(TLOG_ERROR, "add group %s failed, group already exists", group_name);
-		return -1;
+		return 0;
 	}
 
 	group = malloc(sizeof(*group));
@@ -872,6 +916,8 @@ static char *_dns_client_server_get_tls_host_verify(struct dns_server_info *serv
 	} break;
 	case DNS_SERVER_TCP:
 		break;
+	case DNS_SERVER_MDNS:
+		break;
 	default:
 		return NULL;
 		break;
@@ -905,6 +951,8 @@ static char *_dns_client_server_get_spki(struct dns_server_info *server_info, in
 	} break;
 	case DNS_SERVER_TCP:
 		break;
+	case DNS_SERVER_MDNS:
+		break;
 	default:
 		return NULL;
 		break;
@@ -1064,6 +1112,11 @@ static int _dns_client_server_add(char *server_ip, char *server_host, int port,
 	case DNS_SERVER_TCP:
 		sock_type = SOCK_STREAM;
 		break;
+	case DNS_SERVER_MDNS: {
+		struct client_dns_server_flag_mdns *flag_mdns = &flags->mdns;
+		safe_strncpy(flag_mdns->ifname, server_host, DNS_MAX_CNAME_LEN);
+		sock_type = SOCK_DGRAM;
+	} break;
 	default:
 		return -1;
 		break;
@@ -1168,9 +1221,8 @@ static int _dns_client_server_add(char *server_ip, char *server_host, int port,
 	list_add(&server_info->list, &client.dns_server_list);
 	pthread_mutex_unlock(&client.server_list_lock);
 
-	atomic_inc(&client.dns_server_num);
+	_dns_server_inc_server_num(server_info);
 	freeaddrinfo(gai);
-
 	tlog(TLOG_INFO, "add server %s:%d, type: %s", server_ip, port, _dns_server_get_type_string(server_info->type));
 
 	return 0;
@@ -1250,6 +1302,8 @@ static void _dns_client_shutdown_socket(struct dns_server_info *server_info)
 			shutdown(server_info->fd, SHUT_RDWR);
 		}
 		break;
+	case DNS_SERVER_MDNS:
+		break;
 	default:
 		break;
 	}
@@ -1312,8 +1366,8 @@ static int _dns_client_server_remove(char *server_ip, int port, dns_server_type_
 		_dns_client_server_close(server_info);
 		pthread_mutex_unlock(&client.server_list_lock);
 		_dns_client_remove_server_from_groups(server_info);
+		_dns_server_dec_server_num(server_info);
 		free(server_info);
-		atomic_dec(&client.dns_server_num);
 		return 0;
 	}
 	pthread_mutex_unlock(&client.server_list_lock);
@@ -1585,7 +1639,7 @@ static void _dns_client_check_tcp(void)
 	pthread_mutex_lock(&client.server_list_lock);
 	list_for_each_entry(server_info, &client.dns_server_list, list)
 	{
-		if (server_info->type == DNS_SERVER_UDP) {
+		if (server_info->type == DNS_SERVER_UDP || server_info->type == DNS_SERVER_MDNS) {
 			/* no need to check udp server */
 			continue;
 		}
@@ -1929,6 +1983,74 @@ errout:
 	return -1;
 }
 
+#include <net/if.h>
+#include <sys/ioctl.h>
+
+static int _dns_client_create_socket_udp_mdns(struct dns_server_info *server_info)
+{
+	int fd = 0;
+	struct epoll_event event;
+	const int on = 1;
+	const int val = 1;
+	const int priority = SOCKET_PRIORITY;
+	const int ip_tos = SOCKET_IP_TOS;
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0) {
+		tlog(TLOG_ERROR, "create socket failed, %s", strerror(errno));
+		goto errout;
+	}
+
+	if (set_fd_nonblock(fd, 1) != 0) {
+		tlog(TLOG_ERROR, "set socket non block failed, %s", strerror(errno));
+		goto errout;
+	}
+
+	struct ifreq ifr;
+	memset(&ifr, 0, sizeof(struct ifreq));
+	safe_strncpy(ifr.ifr_name, server_info->flags.mdns.ifname, sizeof(ifr.ifr_name));
+	ioctl(fd, SIOCGIFINDEX, &ifr);
+	if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(struct ifreq)) < 0) {
+		tlog(TLOG_ERROR, "bind socket to device %s failed, %s\n", ifr.ifr_name, strerror(errno));
+		goto errout;
+	}
+
+	server_info->fd = fd;
+	server_info->status = DNS_SERVER_STATUS_CONNECTIONLESS;
+
+	memset(&event, 0, sizeof(event));
+	event.events = EPOLLIN;
+	event.data.ptr = server_info;
+	if (epoll_ctl(client.epoll_fd, EPOLL_CTL_ADD, fd, &event) != 0) {
+		tlog(TLOG_ERROR, "epoll ctl failed.");
+		return -1;
+	}
+
+	setsockopt(server_info->fd, IPPROTO_IP, IP_RECVTTL, &on, sizeof(on));
+	setsockopt(server_info->fd, SOL_IP, IP_TTL, &val, sizeof(val));
+	setsockopt(server_info->fd, SOL_SOCKET, SO_PRIORITY, &priority, sizeof(priority));
+	setsockopt(server_info->fd, IPPROTO_IP, IP_TOS, &ip_tos, sizeof(ip_tos));
+	setsockopt(server_info->fd, IPPROTO_IP, IP_MULTICAST_TTL, &val, sizeof(val));
+	if (server_info->ai_family == AF_INET6) {
+		/* for receiving ip ttl value */
+		setsockopt(server_info->fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &on, sizeof(on));
+		setsockopt(server_info->fd, IPPROTO_IPV6, IPV6_2292HOPLIMIT, &on, sizeof(on));
+		setsockopt(server_info->fd, IPPROTO_IPV6, IPV6_HOPLIMIT, &on, sizeof(on));
+		setsockopt(server_info->fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
+	}
+
+	return 0;
+errout:
+	if (fd > 0) {
+		close(fd);
+	}
+
+	server_info->fd = -1;
+	server_info->status = DNS_SERVER_STATUS_DISCONNECTED;
+
+	return -1;
+}
+
 static int _DNS_client_create_socket_tcp(struct dns_server_info *server_info)
 {
 	int fd = 0;
@@ -2171,6 +2293,8 @@ static int _dns_client_create_socket(struct dns_server_info *server_info)
 
 	if (server_info->type == DNS_SERVER_UDP) {
 		return _dns_client_create_socket_udp(server_info);
+	} else if (server_info->type == DNS_SERVER_MDNS) {
+		return _dns_client_create_socket_udp_mdns(server_info);
 	} else if (server_info->type == DNS_SERVER_TCP) {
 		return _DNS_client_create_socket_tcp(server_info);
 	} else if (server_info->type == DNS_SERVER_TLS) {
@@ -2556,6 +2680,8 @@ static int _dns_client_socket_send(struct dns_server_info *server_info)
 			}
 		}
 		return ret;
+	} else if (server_info->type == DNS_SERVER_MDNS) {
+		return -1;
 	} else {
 		return -1;
 	}
@@ -2579,6 +2705,8 @@ static int _dns_client_socket_recv(struct dns_server_info *server_info)
 		}
 
 		return ret;
+	} else if (server_info->type == DNS_SERVER_MDNS) {
+		return -1;
 	} else {
 		return -1;
 	}
@@ -3181,7 +3309,7 @@ static int _dns_client_process(struct dns_server_info *server_info, struct epoll
 		}
 	}
 
-	if (server_info->type == DNS_SERVER_UDP) {
+	if (server_info->type == DNS_SERVER_UDP || server_info->type == DNS_SERVER_MDNS) {
 		/* receive from udp */
 		return _dns_client_process_udp(server_info, event, now);
 	} else if (server_info->type == DNS_SERVER_TCP) {
@@ -3261,6 +3389,27 @@ errout:
 	return -1;
 }
 
+static int _dns_client_send_udp_mdns(struct dns_server_info *server_info, void *packet, int len)
+{
+	int send_len = 0;
+	const struct sockaddr *addr = &server_info->addr;
+	socklen_t addrlen = server_info->ai_addrlen;
+
+	if (server_info->fd <= 0) {
+		return -1;
+	}
+
+	send_len = sendto(server_info->fd, packet, len, 0, addr, addrlen);
+	if (send_len != len) {
+		goto errout;
+	}
+
+	return 0;
+
+errout:
+	return -1;
+}
+
 static int _dns_client_send_data_to_buffer(struct dns_server_info *server_info, void *packet, int len)
 {
 	struct epoll_event event;
@@ -3483,7 +3632,7 @@ static int _dns_client_setup_server_packet(struct dns_server_info *server_info,
 		dns_set_OPT_option(packet, DNS_OPT_FLAG_DO);
 	}
 
-	if (server_info->type != DNS_SERVER_UDP) {
+	if (server_info->type != DNS_SERVER_UDP && server_info->type != DNS_SERVER_MDNS) {
 		dns_add_OPT_TCP_KEEPALIVE(packet, 6000);
 	}
 
@@ -3549,7 +3698,7 @@ static int _dns_client_send_packet(struct dns_query_struct *query, void *packet,
 			if (server_info->prohibit) {
 				if (server_info->is_already_prohibit == 0) {
 					server_info->is_already_prohibit = 1;
-					atomic_inc(&client.dns_server_prohibit_num);
+					_dns_server_inc_prohibit_server_num(server_info);
 					time(&server_info->last_send);
 					time(&server_info->last_recv);
 					tlog(TLOG_INFO, "server %s not alive, prohibit", server_info->ip);
@@ -3563,7 +3712,7 @@ static int _dns_client_send_packet(struct dns_query_struct *query, void *packet,
 				}
 				server_info->prohibit = 0;
 				server_info->is_already_prohibit = 0;
-				atomic_dec(&client.dns_server_prohibit_num);
+				_dns_server_dec_prohibit_server_num(server_info);
 				if (now - 60 > server_info->last_send) {
 					_dns_client_close_socket(server_info);
 				}
@@ -3609,6 +3758,11 @@ static int _dns_client_send_packet(struct dns_query_struct *query, void *packet,
 				ret = _dns_client_send_https(server_info, packet_data, packet_data_len);
 				send_err = errno;
 				break;
+			case DNS_SERVER_MDNS:
+				/* mdns query */
+				ret = _dns_client_send_udp_mdns(server_info, packet_data, packet_data_len);
+				send_err = errno;
+				break;
 			default:
 				/* unsupported query type */
 				ret = -1;
@@ -4440,6 +4594,78 @@ static void _dns_client_do_wakeup_event(void)
 	unused = write(client.fd_wakeup, &val, sizeof(val));
 }
 
+static int _dns_client_add_mdns_server(void)
+{
+	struct client_dns_server_flags server_flags;
+	int ret = 0;
+	struct ifaddrs *ifaddr = NULL;
+	struct ifaddrs *ifa = NULL;
+
+	if (dns_conf_mdns_lookup != 1) {
+		return 0;
+	}
+
+	memset(&server_flags, 0, sizeof(server_flags));
+	server_flags.server_flag |= SERVER_FLAG_EXCLUDE_DEFAULT | DOMAIN_FLAG_IPSET_IGN | DOMAIN_FLAG_NFTSET_INET_IGN;
+
+	if (dns_client_add_group(DNS_SERVER_GROUP_MDNS) != 0) {
+		tlog(TLOG_ERROR, "add default server group failed.");
+		goto errout;
+	}
+
+	if (getifaddrs(&ifaddr) == -1) {
+		goto errout;
+	}
+
+	for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
+		const unsigned char *addr = NULL;
+		int addr_len = 0;
+
+		if (ifa->ifa_addr == NULL) {
+			continue;
+		}
+
+		if (AF_INET != ifa->ifa_addr->sa_family) {
+			continue;
+		}
+
+		addr = (const unsigned char *)&((struct sockaddr_in *)ifa->ifa_addr)->sin_addr;
+		addr_len = sizeof(struct in_addr);
+
+		// Skip the local interface
+		if (strcmp(ifa->ifa_name, "lo") == 0 || strcmp(ifa->ifa_name, "localhost") == 0) {
+			continue;
+		}
+
+		if (is_private_addr(addr, addr_len) == 0) {
+			continue;
+		}
+
+		ret = _dns_client_server_add(DNS_MDNS_IP, ifa->ifa_name, DNS_MDNS_PORT, DNS_SERVER_MDNS, &server_flags);
+		if (ret != 0) {
+			tlog(TLOG_ERROR, "add mdns server failed.");
+			goto errout;
+		}
+
+		if (dns_client_add_to_group(DNS_SERVER_GROUP_MDNS, DNS_MDNS_IP, DNS_MDNS_PORT, DNS_SERVER_MDNS,
+									&server_flags) != 0) {
+			tlog(TLOG_ERROR, "add mdns server to group failed.");
+			goto errout;
+		}
+	}
+
+	freeifaddrs(ifaddr);
+
+	return 0;
+
+errout:
+	if (ifaddr) {
+		freeifaddrs(ifaddr);
+	}
+
+	return -1;
+}
+
 int dns_client_init(void)
 {
 	pthread_attr_t attr;
@@ -4480,6 +4706,11 @@ int dns_client_init(void)
 		goto errout;
 	}
 
+	if (_dns_client_add_mdns_server() != 0) {
+		tlog(TLOG_ERROR, "add mdns server failed.");
+		goto errout;
+	}
+
 	client.default_group = _dns_client_get_group(DNS_SERVER_GROUP_DEFAULT);
 	client.epoll_fd = epollfd;
 	atomic_set(&client.run, 1);

src/dns_client.h

@@ -27,12 +27,15 @@ extern "C" {
 
 #define DNS_SERVER_SPKI_LEN 64
 #define DNS_SERVER_GROUP_DEFAULT "default"
+#define DNS_SERVER_GROUP_MDNS "mdns"
+#define DNS_SERVER_GROUP_LOCAL "local"
 
 typedef enum {
 	DNS_SERVER_UDP,
 	DNS_SERVER_TCP,
 	DNS_SERVER_TLS,
 	DNS_SERVER_HTTPS,
+	DNS_SERVER_MDNS,
 	DNS_SERVER_TYPE_END,
 } dns_server_type_t;
 
@@ -90,6 +93,10 @@ struct client_dns_server_flag_udp {
 	int ttl;
 };
 
+struct client_dns_server_flag_mdns {
+	char ifname[DNS_MAX_CNAME_LEN];
+};
+
 struct client_dns_server_flag_tls {
 	char spki[DNS_SERVER_SPKI_LEN];
 	int spi_len;
@@ -129,6 +136,7 @@ struct client_dns_server_flags {
 		struct client_dns_server_flag_udp udp;
 		struct client_dns_server_flag_tls tls;
 		struct client_dns_server_flag_https https;
+		struct client_dns_server_flag_mdns mdns;
 	};
 };
 

src/dns_conf.c

@@ -162,6 +162,7 @@ struct dns_ipset_names dns_conf_ipset_no_speed;
 int dns_conf_nftset_timeout_enable;
 struct dns_nftset_names dns_conf_nftset_no_speed;
 int dns_conf_nftset_debug_enable;
+int dns_conf_mdns_lookup;
 
 char dns_conf_user[DNS_CONF_USERNAME_LEN];
 
@@ -3967,16 +3968,15 @@ static struct dns_hosts *_dns_conf_get_hosts(const char *hostname, int dns_type)
 {
 	uint32_t key = 0;
 	struct dns_hosts *host = NULL;
-	char hostname_lower[DNS_MAX_CNAME_LEN];
 
-	key = hash_string(to_lower_case(hostname_lower, hostname, DNS_MAX_CNAME_LEN));
+	key = hash_string_case(hostname);
 	key = jhash(&dns_type, sizeof(dns_type), key);
 	hash_for_each_possible(dns_hosts_table.hosts, host, node, key)
 	{
 		if (host->dns_type != dns_type) {
 			continue;
 		}
-		if (strncmp(host->domain, hostname_lower, DNS_MAX_CNAME_LEN) != 0) {
+		if (strncasecmp(host->domain, hostname, DNS_MAX_CNAME_LEN) != 0) {
 			continue;
 		}
 
@@ -3988,7 +3988,7 @@ static struct dns_hosts *_dns_conf_get_hosts(const char *hostname, int dns_type)
 		goto errout;
 	}
 
-	safe_strncpy(host->domain, hostname_lower, DNS_MAX_CNAME_LEN);
+	safe_strncpy(host->domain, hostname, DNS_MAX_CNAME_LEN);
 	host->dns_type = dns_type;
 	host->is_soa = 1;
 	hash_add(dns_hosts_table.hosts, &host->node, key);
@@ -4275,6 +4275,15 @@ static void _config_setup_smartdns_domain(void)
 	_config_domain_rule_flag_set("smartdns", DOMAIN_FLAG_SMARTDNS_DOMAIN, 0);
 }
 
+static int _dns_conf_setup_mdns(void)
+{
+	if (dns_conf_mdns_lookup != 1) {
+		return 0;
+	}
+
+	return _conf_domain_rule_nameserver(DNS_SERVER_GROUP_LOCAL, DNS_SERVER_GROUP_MDNS);
+}
+
 static struct config_item _config_item[] = {
 	CONF_STRING("server-name", (char *)dns_conf_server_name, DNS_MAX_SERVER_NAME_LEN),
 	CONF_YESNO("resolv-hostname", &dns_conf_resolv_hostname),
@@ -4289,6 +4298,7 @@ static struct config_item _config_item[] = {
 	CONF_CUSTOM("server-tcp", _config_server_tcp, NULL),
 	CONF_CUSTOM("server-tls", _config_server_tls, NULL),
 	CONF_CUSTOM("server-https", _config_server_https, NULL),
+	CONF_YESNO("mdns-lookup", &dns_conf_mdns_lookup),
 	CONF_CUSTOM("nameserver", _config_nameserver, NULL),
 	CONF_YESNO("expand-ptr-from-address", &dns_conf_expand_ptr_from_address),
 	CONF_CUSTOM("address", _config_address, NULL),
@@ -4728,6 +4738,8 @@ static int _dns_conf_load_post(void)
 
 	_dns_conf_auto_set_cache_size();
 
+	_dns_conf_setup_mdns();
+
 	if (dns_conf_cachesize == 0 && dns_conf_response_mode == DNS_RESPONSE_MODE_FASTEST_RESPONSE) {
 		dns_conf_response_mode = DNS_RESPONSE_MODE_FASTEST_IP;
 		tlog(TLOG_WARN, "force set response to %s as cache size is 0",

src/dns_conf.h

@@ -578,6 +578,7 @@ extern int dns_conf_ipset_timeout_enable;
 extern int dns_conf_nftset_timeout_enable;
 extern int dns_conf_nftset_debug_enable;
 extern int dns_conf_local_ttl;
+extern int dns_conf_mdns_lookup;
 
 extern int dns_conf_force_no_cname;
 

src/dns_server.c

@@ -280,6 +280,8 @@ struct dns_request {
 	int has_soa;
 	int force_soa;
 
+	int is_mdns_lookup;
+
 	struct dns_srv_records *srv_records;
 
 	atomic_t notified;
@@ -365,6 +367,7 @@ static int _dns_server_do_query(struct dns_request *request, int skip_notify_eve
 static int _dns_request_post(struct dns_server_post_context *context);
 static int _dns_server_reply_all_pending_list(struct dns_request *request, struct dns_server_post_context *context);
 static void *_dns_server_get_dns_rule(struct dns_request *request, enum domain_rule rule);
+static int _dns_server_get_local_ttl(struct dns_request *request);
 static const char *_dns_server_get_request_groupname(struct dns_request *request);
 static int _dns_server_tcp_socket_send(struct dns_server_conn_tcp_client *tcp_client, void *data, int data_len);
 static int _dns_server_update_request_connection_timeout(struct dns_server_conn_head *conn, int timeout);
@@ -761,8 +764,8 @@ static void _dns_server_audit_log(struct dns_server_post_context *context)
 					continue;
 				}
 
-				if (strncmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
-					strncmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
+				if (strncasecmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
+					strncasecmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
 					continue;
 				}
 
@@ -782,8 +785,8 @@ static void _dns_server_audit_log(struct dns_server_post_context *context)
 					continue;
 				}
 
-				if (strncmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
-					strncmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
+				if (strncasecmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
+					strncasecmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
 					continue;
 				}
 
@@ -1559,7 +1562,7 @@ static int _dns_cache_cname_packet(struct dns_server_post_context *context)
 					continue;
 				}
 
-				if (strncmp(request->cname, name, DNS_MAX_CNAME_LEN - 1) != 0) {
+				if (strncasecmp(request->cname, name, DNS_MAX_CNAME_LEN - 1) != 0) {
 					continue;
 				}
 
@@ -1575,7 +1578,7 @@ static int _dns_cache_cname_packet(struct dns_server_post_context *context)
 					continue;
 				}
 
-				if (strncmp(request->cname, name, DNS_MAX_CNAME_LEN - 1) != 0) {
+				if (strncasecmp(request->cname, name, DNS_MAX_CNAME_LEN - 1) != 0) {
 					continue;
 				}
 
@@ -2770,6 +2773,9 @@ static void _dns_server_ping_result(struct ping_host_struct *ping_host, const ch
 	}
 
 	int rtt = tv->tv_sec * 10000 + tv->tv_usec / 100;
+	if (rtt == 0) {
+		rtt = 1;
+	}
 
 	if (result == PING_RESULT_RESPONSE) {
 		tlog(TLOG_DEBUG, "from %s: seq=%d time=%d, lasttime=%d id=%d", host, seqno, rtt, last_rtt, request->id);
@@ -3127,7 +3133,7 @@ static int _dns_server_process_answer_A(struct dns_rrs *rrs, struct dns_request
 	tlog(TLOG_DEBUG, "domain: %s TTL: %d IP: %d.%d.%d.%d", name, ttl, addr[0], addr[1], addr[2], addr[3]);
 
 	/* if domain is not match */
-	if (strncmp(name, domain, DNS_MAX_CNAME_LEN) != 0 && strncmp(cname, name, DNS_MAX_CNAME_LEN) != 0) {
+	if (strncasecmp(name, domain, DNS_MAX_CNAME_LEN) != 0 && strncasecmp(cname, name, DNS_MAX_CNAME_LEN) != 0) {
 		return -1;
 	}
 
@@ -3214,7 +3220,7 @@ static int _dns_server_process_answer_AAAA(struct dns_rrs *rrs, struct dns_reque
 		 addr[11], addr[12], addr[13], addr[14], addr[15]);
 
 	/* if domain is not match */
-	if (strncmp(name, domain, DNS_MAX_CNAME_LEN) != 0 && strncmp(cname, name, DNS_MAX_CNAME_LEN) != 0) {
+	if (strncasecmp(name, domain, DNS_MAX_CNAME_LEN) != 0 && strncasecmp(cname, name, DNS_MAX_CNAME_LEN) != 0) {
 		return -1;
 	}
 
@@ -3338,8 +3344,8 @@ static int _dns_server_process_answer(struct dns_request *request, const char *d
 				char domain_name[DNS_MAX_CNAME_LEN] = {0};
 				char domain_cname[DNS_MAX_CNAME_LEN] = {0};
 				dns_get_CNAME(rrs, domain_name, DNS_MAX_CNAME_LEN, &ttl, domain_cname, DNS_MAX_CNAME_LEN);
-				if (strncmp(domain_name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
-					strncmp(domain_name, cname, DNS_MAX_CNAME_LEN - 1) != 0) {
+				if (strncasecmp(domain_name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
+					strncasecmp(domain_name, cname, DNS_MAX_CNAME_LEN - 1) != 0) {
 					continue;
 				}
 				safe_strncpy(cname, domain_cname, DNS_MAX_CNAME_LEN);
@@ -3431,7 +3437,8 @@ static int _dns_server_passthrough_rule_check(struct dns_request *request, const
 				dns_get_A(rrs, name, DNS_MAX_CNAME_LEN, &ttl_tmp, addr);
 
 				/* if domain is not match */
-				if (strncmp(name, domain, DNS_MAX_CNAME_LEN) != 0 && strncmp(cname, name, DNS_MAX_CNAME_LEN) != 0) {
+				if (strncasecmp(name, domain, DNS_MAX_CNAME_LEN) != 0 &&
+					strncasecmp(cname, name, DNS_MAX_CNAME_LEN) != 0) {
 					_dns_server_request_release(request);
 					continue;
 				}
@@ -3470,7 +3477,8 @@ static int _dns_server_passthrough_rule_check(struct dns_request *request, const
 				dns_get_AAAA(rrs, name, DNS_MAX_CNAME_LEN, &ttl_tmp, addr);
 
 				/* if domain is not match */
-				if (strncmp(name, domain, DNS_MAX_CNAME_LEN) != 0 && strncmp(cname, name, DNS_MAX_CNAME_LEN) != 0) {
+				if (strncasecmp(name, domain, DNS_MAX_CNAME_LEN) != 0 &&
+					strncasecmp(cname, name, DNS_MAX_CNAME_LEN) != 0) {
 					_dns_server_request_release(request);
 					continue;
 				}
@@ -3552,8 +3560,8 @@ static int _dns_server_get_answer(struct dns_server_post_context *context)
 				/* get A result */
 				dns_get_A(rrs, name, DNS_MAX_CNAME_LEN, &ttl, addr);
 
-				if (strncmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
-					strncmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
+				if (strncasecmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
+					strncasecmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
 					continue;
 				}
 
@@ -3584,8 +3592,8 @@ static int _dns_server_get_answer(struct dns_server_post_context *context)
 				}
 				dns_get_AAAA(rrs, name, DNS_MAX_CNAME_LEN, &ttl, addr);
 
-				if (strncmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
-					strncmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
+				if (strncasecmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
+					strncasecmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
 					continue;
 				}
 
@@ -3619,8 +3627,8 @@ static int _dns_server_get_answer(struct dns_server_post_context *context)
 
 				dns_get_CNAME(rrs, name, DNS_MAX_CNAME_LEN, &ttl, cname, DNS_MAX_CNAME_LEN);
 				tlog(TLOG_DEBUG, "name: %s, ttl: %d, cname: %s\n", name, ttl, cname);
-				if (strncmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
-					strncmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
+				if (strncasecmp(name, request->domain, DNS_MAX_CNAME_LEN - 1) != 0 &&
+					strncasecmp(name, request->cname, DNS_MAX_CNAME_LEN - 1) != 0) {
 					continue;
 				}
 
@@ -3698,6 +3706,13 @@ static void _dns_server_query_end(struct dns_request *request)
 	int ip_num = 0;
 	int request_wait = 0;
 
+	/* if mdns request timeout */
+	if (request->is_mdns_lookup == 1 && request->rcode == DNS_RC_SERVFAIL) {
+		request->rcode = DNS_RC_NOERROR;
+		request->force_soa = 1;
+		request->ip_ttl = _dns_server_get_local_ttl(request);
+	}
+
 	pthread_mutex_lock(&request->ip_map_lock);
 	ip_num = atomic_read(&request->ip_map_num);
 	request_wait = request->request_wait;
@@ -4100,7 +4115,7 @@ static int _dns_server_process_local_ptr(struct dns_request *request)
 	}
 
 	/* Determine if the smartdns service is in effect. */
-	if (found == 0 && strncmp(request->domain, "smartdns", sizeof("smartdns")) == 0) {
+	if (found == 0 && strncasecmp(request->domain, "smartdns", sizeof("smartdns")) == 0) {
 		found = 1;
 	}
 
@@ -4179,6 +4194,15 @@ static int _dns_server_get_local_ttl(struct dns_request *request)
 	return DNS_SERVER_ADDR_TTL;
 }
 
+static void _dns_server_set_request_mdns(struct dns_request *request)
+{
+	if (dns_conf_mdns_lookup != 1) {
+		return;
+	}
+
+	request->is_mdns_lookup = 1;
+}
+
 static int _dns_server_process_private_ptr(struct dns_request *request)
 {
 	int a, b, c, d;
@@ -4188,9 +4212,12 @@ static int _dns_server_process_private_ptr(struct dns_request *request)
 	}
 
 	if (d == 10 || (d == 172 && c >= 16 && c <= 31) || (d == 192 && c == 168)) {
-		request->has_soa = 1;
-		_dns_server_setup_soa(request);
-		return 0;
+		if (dns_conf_mdns_lookup == 0) {
+			request->has_soa = 1;
+			_dns_server_setup_soa(request);
+			return 0;
+		}
+		_dns_server_set_request_mdns(request);
 	}
 
 	return -1;
@@ -4253,7 +4280,7 @@ static int _dns_server_process_srv(struct dns_request *request)
 
 static int _dns_server_process_svcb(struct dns_request *request)
 {
-	if (strncmp("_dns.resolver.arpa", request->domain, DNS_MAX_CNAME_LEN) == 0) {
+	if (strncasecmp("_dns.resolver.arpa", request->domain, DNS_MAX_CNAME_LEN) == 0) {
 		return _dns_server_process_DDR(request);
 	}
 
@@ -4842,7 +4869,7 @@ static int _dns_server_process_cname(struct dns_request *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) {
+	if (child_cname != NULL && strncasecmp(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;
 	}
@@ -5462,13 +5489,12 @@ static int _dns_server_process_host(struct dns_request *request)
 	struct dns_hosts *host = NULL;
 	struct dns_hosts *host_tmp = NULL;
 	int dns_type = request->qtype;
-	char hostname_lower[DNS_MAX_CNAME_LEN];
 
 	if (dns_hosts_record_num <= 0) {
 		return -1;
 	}
 
-	key = hash_string(to_lower_case(hostname_lower, request->domain, DNS_MAX_CNAME_LEN));
+	key = hash_string_case(request->domain);
 	key = jhash(&dns_type, sizeof(dns_type), key);
 	hash_for_each_possible(dns_hosts_table.hosts, host_tmp, node, key)
 	{
@@ -5476,7 +5502,7 @@ static int _dns_server_process_host(struct dns_request *request)
 			continue;
 		}
 
-		if (strncmp(host_tmp->domain, hostname_lower, DNS_MAX_CNAME_LEN) != 0) {
+		if (strncasecmp(host_tmp->domain, request->domain, DNS_MAX_CNAME_LEN) != 0) {
 			continue;
 		}
 
@@ -5536,6 +5562,35 @@ static int _dns_server_setup_query_option(struct dns_request *request, struct dn
 	return 0;
 }
 
+static int _dns_server_mdns_query_setup(struct dns_request *request, const char *group_name, char **request_domain,
+										char *domain_buffer, int domain_buffer_len)
+{
+
+	if (dns_conf_mdns_lookup != 1) {
+		return 0;
+	}
+
+	switch (request->qtype) {
+	case DNS_T_A:
+	case DNS_T_AAAA:
+	case DNS_T_SRV:
+		if (request->domain[0] != '\0' && strstr(request->domain, ".") == NULL) {
+			snprintf(domain_buffer, domain_buffer_len, "%s.%s", request->domain, DNS_SERVER_GROUP_LOCAL);
+			*request_domain = domain_buffer;
+			_dns_server_set_request_mdns(request);
+		}
+
+		if (group_name != NULL && strncmp(group_name, DNS_SERVER_GROUP_MDNS, DNS_GROUP_NAME_LEN) == 0) {
+			_dns_server_set_request_mdns(request);
+		}
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
 static int _dns_server_query_dualstack(struct dns_request *request)
 {
 	int ret = -1;
@@ -5598,6 +5653,8 @@ static int _dns_server_do_query(struct dns_request *request, int skip_notify_eve
 	const char *group_name = NULL;
 	const char *dns_group = NULL;
 	struct dns_query_options options;
+	char *request_domain = request->domain;
+	char domain_buffer[DNS_MAX_CNAME_LEN * 2];
 
 	if (request->conn) {
 		dns_group = request->conn->dns_group;
@@ -5691,10 +5748,19 @@ static int _dns_server_do_query(struct dns_request *request, int skip_notify_eve
 	list_add_tail(&request->list, &server.request_list);
 	pthread_mutex_unlock(&server.request_list_lock);
 
+	if (_dns_server_mdns_query_setup(request, group_name, &request_domain, domain_buffer, sizeof(domain_buffer)) != 0) {
+		goto errout;
+	}
+
+	/* if request MDNS */
+	if (request->is_mdns_lookup) {
+		group_name = DNS_SERVER_GROUP_MDNS;
+	}
+
 	// Get reference for DNS query
 	request->request_wait++;
 	_dns_server_request_get(request);
-	if (dns_client_query(request->domain, request->qtype, dns_server_resolve_callback, request, group_name, &options) !=
+	if (dns_client_query(request_domain, request->qtype, dns_server_resolve_callback, request, group_name, &options) !=
 		0) {
 		request->request_wait--;
 		_dns_server_request_release(request);
@@ -6464,7 +6530,7 @@ static int _dns_server_tcp_process_one_request(struct dns_server_conn_tcp_client
 
 			const char *content_type = http_head_get_fields_value(http_head, "Content-Type");
 			if (content_type == NULL ||
-				strncmp(content_type, "application/dns-message", sizeof("application/dns-message")) != 0) {
+				strncasecmp(content_type, "application/dns-message", sizeof("application/dns-message")) != 0) {
 				tlog(TLOG_DEBUG, "content type not supported, %s", content_type);
 				goto errout;
 			}

src/util.c

@@ -218,6 +218,33 @@ int generate_addr_map(const unsigned char *addr_from, const unsigned char *addr_
 	return 0;
 }
 
+int is_private_addr(const unsigned char *addr, int addr_len)
+{
+	if (addr_len == IPV4_ADDR_LEN) {
+		if (addr[0] == 10) {
+			return 1;
+		}
+
+		if (addr[0] == 172 && addr[1] >= 16 && addr[1] <= 31) {
+			return 1;
+		}
+
+		if (addr[0] == 192 && addr[1] == 168) {
+			return 1;
+		}
+	} else if (addr_len == IPV6_ADDR_LEN) {
+		if (addr[0] == 0xFD) {
+			return 1;
+		}
+
+		if (addr[0] == 0xFE && addr[1] == 0x80) {
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 int getaddr_by_host(const char *host, struct sockaddr *addr, socklen_t *addr_len)
 {
 	struct addrinfo hints;

src/util.h

@@ -64,6 +64,8 @@ int generate_random_addr(unsigned char *addr, int addr_len, int mask);
 int generate_addr_map(const unsigned char *addr_from, const unsigned char *addr_to, unsigned char *addr_out,
 					  int addr_len, int mask);
 
+int is_private_addr(const unsigned char *addr, int addr_len);
+
 int getaddr_by_host(const char *host, struct sockaddr *addr, socklen_t *addr_len);
 
 int getsocket_inet(int fd, struct sockaddr *addr, socklen_t *addr_len);