Add luci for new feature, and fix some bugs

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

@@ -113,11 +113,16 @@ load_server()
 {
 	local section="$1"
 	local ADDITIONAL_ARGS=""
+	config_get_bool "enabled" "$section" "enabled" "1"
 	config_get "port" "$section" "port" "53"
 	config_get "type" "$section" "type" "udp"
 	config_get "ip" "$section" "ip" ""
 	config_get "blacklist_ip" "$section" "blacklist_ip" "0"
 
+	if [ "$enabled" = "0" ]; then
+		return
+	fi
+
 	if [ -z "$port" ] || [ -z "$ip" ] || [ -z "$type" ]; then
 		return
 	fi
@@ -167,6 +172,11 @@ start_service() {
 			conf_append "bind-tcp" ":$port"
 		fi
 	fi
+	config_get "dualstack_ip_selection" "$section" "dualstack_ip_selection" "0"
+	if [ "$dualstack_ip_selection" = "1" ]; then
+		conf_append "dualstack-ip-selection" "yes"
+	fi
+
 	SMARTDNS_PORT="$port"
 
 	mkdir -p $SMARTDNS_CONF_DIR
@@ -215,15 +225,26 @@ start_service() {
 	config_get "old_redirect" "$section" "old_redirect" "none"
 	config_get "old_port" "$section" "old_port" "0"
 
-	if [ "$old_redirect" != "none" ] && [ "$old_port" != "0" ]; then
+	if [ "$old_port" != "$SMARTDNS_PORT" ]; then
 		clear_iptable "$old_port" "$ipv6_server"
-		stop_forward_dnsmasq "$old_port"
+		if [ "$redirect" = "redirect" ]; then
+			set_iptable $ipv6_server $tcp_server
+		fi	
 	fi
 
-	if [ "$redirect" = "redirect" ]; then
-		set_iptable $ipv6_server $tcp_server
-	elif [ "$redirect" = "dnsmasq-upstream" ]; then
-		set_forward_dnsmasq "$SMARTDNS_PORT"
+	if [ "$old_redirect" != "$redirect" ]; then
+		if [ "$old_redirect" != "none" ]; then
+			if [ "$old_port" != "0" ]; then
+				clear_iptable "$old_port" "$ipv6_server"
+			fi
+			stop_forward_dnsmasq "$old_port"
+		fi
+
+		if [ "$redirect" = "redirect" ]; then
+			set_iptable $ipv6_server $tcp_server
+		elif [ "$redirect" = "dnsmasq-upstream" ]; then
+			set_forward_dnsmasq "$SMARTDNS_PORT"
+		fi
 	fi
 
 	uci delete smartdns.@smartdns[0].old_redirect 2>/dev/null