[source] odhcp6c: add workaround for broken extendprefix scenario

[LEDE Commits]

dedeckeh pushed a commit to source.git, branch master:
https://git.lede-project.org/995193ccdb2adb2bfe226965589b5f3db71bdd80

commit 995193ccdb2adb2bfe226965589b5f3db71bdd80
Author: Hans Dedecker <dedeckeh at gmail.com>
AuthorDate: Tue Sep 5 14:33:01 2017 +0200

    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 at gmail.com>
---
 package/network/ipv6/odhcp6c/Makefile            |  6 +++---
 package/network/ipv6/odhcp6c/files/dhcpv6.script | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/package/network/ipv6/odhcp6c/Makefile b/package/network/ipv6/odhcp6c/Makefile
index a95a380..457a871 100644
--- a/package/network/ipv6/odhcp6c/Makefile
+++ b/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 at gmail.com>
 PKG_LICENSE:=GPL-2.0
 
diff --git a/package/network/ipv6/odhcp6c/files/dhcpv6.script b/package/network/ipv6/odhcp6c/files/dhcpv6.script
index ab0b556..03efaf7 100755
--- a/package/network/ipv6/odhcp6c/files/dhcpv6.script
+++ b/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