dnsmasq: add match_tag for --dhcp-host

A set of tags can be specified for --dhcp-host option to restrict the
assignment to the requests which match all the tags.

Example usage:

config vendorclass
        option networkid 'udhcp'
        option vendorclass 'udhcp'

config host
        option mac '*:*:*:*:*:*'
        list match_tag 'switch.10'
        list match_tag 'udhcp'
        option ip '192.168.25.10'

Signed-off-by: Paul Fertser <fercerpav@gmail.com>

package/network/services/dnsmasq/files/dnsmasq.init

@@ -332,7 +332,7 @@ dhcp_match_add() {
 
 dhcp_host_add() {
 	local cfg="$1"
-	local hosttag nametime addrs duids macs tags
+	local hosttag nametime addrs duids macs tags mtags
 
 	config_get_bool force "$cfg" force 0
 
@@ -357,6 +357,11 @@ dhcp_host_add() {
 	config_get duid "$cfg" duid
 	config_get tag "$cfg" tag
 
+	add_tag() {
+		mtags="${mtags}tag:$1,"
+	}
+	config_list_foreach "$cfg" match_tag add_tag
+
 	if [ -n "$mac" ]; then
 		# --dhcp-host=00:20:e0:3b:13:af,192.168.0.199,lap
 		# many MAC are possible to track a laptop ON/OFF dock
@@ -394,9 +399,9 @@ dhcp_host_add() {
 
 	if [ $DNSMASQ_DHCP_VER -eq 6 ]; then
 		addrs="${ip:+,$ip}${hostid:+,[::$hostid]}"
-		xappend "--dhcp-host=$macs${duids:+,$duids}$hosttag$addrs$nametime"
+		xappend "--dhcp-host=$mtags$macs${duids:+,$duids}$hosttag$addrs$nametime"
 	else
-		xappend "--dhcp-host=$macs$hosttag${ip:+,$ip}$nametime"
+		xappend "--dhcp-host=$mtags$macs$hosttag${ip:+,$ip}$nametime"
 	fi
 }