dnsmasq: change 'add_local_hostname' to use dnsmasq '--interface-name'

'add_local_hostname' previous implementation may drop some addresses.
Soft addition of IP6 addresses may not cause a reload or restart event.
dnsmasq '--interface-name' robustly applies DNS to all addresses per
interface (except fe80::/10).

Change UCI 'add_local_hostname' to expand during each interface assignement
during add_dhcp().
Assign '<iface>.<host>.<domain>' as true name (reflexive A, AAAA, and PTR).
Assign '<host>.<domain>' and '<host>' as convinience aliases (no PTR, not
technically CNAME).
This is accomplished with the '--interface-name' order, first is PTR.
We could also assign each <ip4/6>.<iface>.<host>.<domain> to the respective
dual stack on the interface.
That seemed excessive so it was skipped (/4 or /6 suffix to the interface).
Add UCI 'add_wan_hostname' similar to 'add_local_hostname' function for
external WAN.

WAN IP4 are less often named by the ISP and rarely WAN IP6 due to complexity.
For logs, LuCI connection graph, and other uses assigning a WAN name is desired.
'add_local_hostname' only applies with DHCP and 'add_wam_hostname' only applies
without DHCP. Common residential users will want to set both options TRUE.
Businesses will probably have global DNS, static IP, and 'add_wan_hostname' FALSE.

Signed-off-by: Eric Luehrsen <ericluehrsen@hotmail.com>

package/network/services/dnsmasq/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=dnsmasq
 PKG_VERSION:=2.76
-PKG_RELEASE:=6
+PKG_RELEASE:=7
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=http://thekelleys.org.uk/dnsmasq

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

@@ -8,6 +8,7 @@ PROG=/usr/sbin/dnsmasq
 
 ADD_LOCAL_DOMAIN=1
 ADD_LOCAL_HOSTNAME=1
+ADD_WAN_HOSTNAME=0
 
 BASECONFIGFILE="/var/etc/dnsmasq.conf"
 BASEHOSTFILE="/tmp/hosts/dhcp"
@@ -293,6 +294,26 @@ dhcp_host_add() {
 	xappend "--dhcp-host=$macs${duid:+,id:$duid}${networkid:+,net:$networkid}${broadcast:+,set:needs-broadcast}${tag:+,set:$tag}${ip:+,$ip${hostid:+,[::$hostid]}}${name:+,$name}${leasetime:+,$leasetime}"
 }
 
+dhcp_this_host_add() {
+	# TODO: case-in do/not short-host or FQDN; UCI already intended ...
+	local ifname="$1"
+	local do_enable="$2"
+	local routerstub routername ifdashname
+
+
+	if [ "$do_enable" -gt 0 ] ; then
+		# All IP addresses discovered by dnsmasq will be labeled robustly (except fe80::)
+		ifdashname="${ifname//./-}"
+		routerstub="$( md5sum /etc/os-release )"
+		routerstub="router-${routerstub// */}"
+		routername="$( uci_get system @system[0] hostname $routerstub )"
+
+		xappend "--interface-name=$ifdashname.$routername.$DOMAIN,$ifname"
+		xappend "--interface-name=$routername.$DOMAIN,$ifname"
+		xappend "--interface-name=$routername,$ifname"
+	fi
+}
+
 dhcp_tag_add() {
 	local cfg="$1"
 
@@ -363,7 +384,11 @@ dhcp_add() {
 		DNS_SERVERS="$DNS_SERVERS $dnsserver"
 	}
 
-	append_bool "$cfg" ignore "--no-dhcp-interface=$ifname" && return 0
+	append_bool "$cfg" ignore "--no-dhcp-interface=$ifname" && {
+		# Many ISP do not have useful names for DHCP customers (your WAN).
+		dhcp_this_host_add $ifname $ADD_WAN_HOSTNAME
+		return 0
+	}
 
 	# Do not support non-static interfaces for now
 	[ static = "$proto" ] || return 0
@@ -381,6 +406,9 @@ dhcp_add() {
 	config_get options "$cfg" options
 	config_get_bool dynamicdhcp "$cfg" dynamicdhcp 1
 
+	# Put the router host name on this DHCP served interface address(es)
+	dhcp_this_host_add $ifname $ADD_LOCAL_HOSTNAME
+
 	leasetime="${leasetime:-12h}"
 	start="$(dhcp_calc "${start:-100}")"
 	limit="${limit:-150}"
@@ -605,6 +633,7 @@ dnsmasq_start()
 
 	config_get_bool ADD_LOCAL_DOMAIN "$cfg" add_local_domain 1
 	config_get_bool ADD_LOCAL_HOSTNAME "$cfg" add_local_hostname 1
+	config_get_bool ADD_WAN_HOSTNAME "$cfg" add_wan_hostname 0
 
 	config_get_bool readethers "$cfg" readethers
 	[ "$readethers" = "1" -a \! -e "/etc/ethers" ] && touch /etc/ethers
@@ -702,27 +731,6 @@ dnsmasq_start()
 	config_foreach filter_dnsmasq hostrecord dhcp_hostrecord_add "$cfg"
 	config_foreach filter_dnsmasq relay dhcp_relay_add "$cfg"
 
-	# add own hostname
-	[ $ADD_LOCAL_HOSTNAME -eq 1 ] && {
-		local lanaddr lanaddr6
-		local ulaprefix="$(uci_get network @globals[0] ula_prefix)"
-		local hostname="$(uci_get system @system[0] hostname Lede)"
-
-		network_get_ipaddr lanaddr "lan" && {
-			dhcp_domain_add "" "$hostname" "$lanaddr"
-		}
-
-		[ -n "$ulaprefix" ] && network_get_ipaddrs6 lanaddr6 "lan" && {
-			for lanaddr6 in $lanaddr6; do
-				case "$lanaddr6" in
-					"${ulaprefix%%:/*}"*)
-						dhcp_domain_add "" "$hostname" "$lanaddr6"
-					;;
-				esac
-			done
-		}
-	}
-
 	echo >> $CONFIGFILE_TMP
 	config_foreach filter_dnsmasq srvhost dhcp_srv_add "$cfg"
 	config_foreach filter_dnsmasq mxhost dhcp_mx_add "$cfg"