odhcp6c: add workaround for broken extendprefix scenario

Extendprefix is typically used to extend an IPv6 RA prefix from a mobile
wan link to the LAN; such scenario requires correct RA prefix settings
like the on link flag not being set.
However some mobile manufacter set the RA prefix on link flag which breaks
basic IPv6 routing.
Work around this issue by filtering out the route being equal to the
extended prefix.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

package/network/ipv6/odhcp6c/Makefile

@@ -8,13 +8,13 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=odhcp6c
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=$(LEDE_GIT)/project/odhcp6c.git
-PKG_SOURCE_DATE:=2017-09-02
+PKG_SOURCE_DATE:=2017-09-05
 PKG_SOURCE_VERSION:=51733a6d3bfe0fb9e8c53aea22231e5b8a1f64c3
-PKG_MIRROR_HASH:=7ab8d3755c588b493792110d871c682cdd8e944ae21db64177321c464c104fb3
+PKG_MIRROR_HASH:=fdccfb9a6cb00d6dbf1a3160bd36622ee8e188a9d58bcd282c71a9368972e184
 PKG_MAINTAINER:=Hans Dedecker <dedeckeh@gmail.com>
 PKG_LICENSE:=GPL-2.0
 

package/network/ipv6/odhcp6c/files/dhcpv6.script

@@ -81,6 +81,23 @@ setup_interface () {
 		# RFC 7278
 		if [ "$mask" -eq 64 -a -z "$PREFIXES" -a -n "$EXTENDPREFIX" ]; then
 			proto_add_ipv6_prefix "$addr/$mask,$preferred,$valid"
+
+			local raroutes=""
+			for route in $RA_ROUTES; do
+				local prefix="${route%%/*}"
+				local entry="${route#*/}"
+				local pmask="${entry%%,*}"
+				entry="${entry#*,}"
+				local gw="${entry%%,*}"
+
+				[ -z "$gw" -a "$mask" = "$pmask" ] && {
+					case "$addr" in
+						"${prefix%*::}"*) continue;;
+					esac
+				}
+				raroutes="$raroutes $route"
+			done
+			RA_ROUTES="$raroutes"
 		fi
 	done