dnsmasq: Invoke new ipcalc with CIDR notation

The new rewritten ipcalc.sh understands 3 notations:

ipaddr/prefix ...
ipaddr/dotted-netmask ...
ipaddr dotted-netmask ...

meaning that the previous 4th non-standard notation of "ipaddr prefix"
will be dropped, alas that's the notation that dnsmasq currently uses.

This change has us using the first notation which is the most common.

This behavior came in as
eda27e8382
a long time ago.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>

package/network/services/dnsmasq/Makefile

@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 PKG_NAME:=dnsmasq
 PKG_UPSTREAM_VERSION:=2.89
 PKG_VERSION:=$(subst test,~~test,$(subst rc,~rc,$(PKG_UPSTREAM_VERSION)))
-PKG_RELEASE:=6
+PKG_RELEASE:=7
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_UPSTREAM_VERSION).tar.xz
 PKG_SOURCE_URL:=https://thekelleys.org.uk/dnsmasq/

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

@@ -539,8 +539,13 @@ dhcp_add() {
 	# Do not support non-static interfaces for now
 	[ static = "$proto" ] || return 0
 
+	ipaddr="${subnet%%/*}"
+	prefix_or_netmask="${subnet##*/}"
+
 	# Override interface netmask with dhcp config if applicable
-	config_get netmask "$cfg" netmask "${subnet##*/}"
+	config_get netmask "$cfg" netmask
+
+	[ -n "$netmask" ] && prefix_or_netmask="$netmask"
 
 	#check for an already active dhcp server on the interface, unless 'force' is set
 	config_get_bool force "$cfg" force 0
@@ -583,7 +588,7 @@ dhcp_add() {
 	nettag="${networkid:+set:${networkid},}"
 
 	# make sure the DHCP range is not empty
-	if [ "$dhcpv4" != "disabled" ] && ipcalc "${subnet%%/*}" "$netmask" "$start" "$limit" ; then
+	if [ "$dhcpv4" != "disabled" ] && ipcalc "$ipaddr/$prefix_or_netmask" "$start" "$limit" ; then
 		[ "$dynamicdhcpv4" = "0" ] && END="static"
 
 		xappend "--dhcp-range=$tags$nettag$START,$END,$NETMASK,$leasetime${options:+ $options}"