mwan3: strip dead flag from copied routes

The kernel marks routes using no-carrier devices as dead linkdown. mwan3
strips linkdown but passes dead to ip route, which rejects the copied route
and leaves policy tables incomplete.

Strip both flags, including at end of line, and add a runtime test.

Signed-off-by: Gleb Pesin <dormancygrace@gmail.com>

net/mwan3/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=mwan3
 PKG_VERSION:=2.12.2
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_MAINTAINER:=Florian Eckert <fe@dev.tdt.de>
 PKG_LICENSE:=GPL-2.0

net/mwan3/files/lib/mwan3/common.sh

@@ -157,7 +157,7 @@ mwan3_get_mwan3track_status()
 
 mwan3_init()
 {
-	local bitcnt mmdefault source_routing
+	local bitcnt mmdefault route_modifiers source_routing
 
 	config_load mwan3
 
@@ -180,10 +180,14 @@ mwan3_init()
 		LOG debug "Max interface count is ${MWAN3_INTERFACE_MAX}"
 	fi
 
-	# remove "linkdown", expiry and source based routing modifiers from route lines
+	# remove unsupported flags, expiry and source based routing modifiers
 	config_get_bool source_routing globals source_routing 0
 	[ $source_routing -eq 1 ] && unset source_routing
-	MWAN3_ROUTE_LINE_EXP="s/offload//; s/linkdown //; s/expires [0-9]\+sec//; s/error [0-9]\+//; ${source_routing:+s/default\(.*\) from [^ ]*/default\1/;} p"
+	route_modifiers="s/offload//; s/ dead / /; s/ dead$/ /;"
+	route_modifiers="$route_modifiers s/ linkdown / /; s/ linkdown$/ /;"
+	route_modifiers="$route_modifiers s/expires [0-9]\+sec//;"
+	route_modifiers="$route_modifiers s/error [0-9]\+//;"
+	MWAN3_ROUTE_LINE_EXP="$route_modifiers ${source_routing:+s/default\(.*\) from [^ ]*/default\1/;} p"
 
 	# mark mask constants
 	bitcnt=$(mwan3_count_one_bits MMX_MASK)

net/mwan3/test.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+
+# shellcheck shell=busybox
+
+IPKG_INSTROOT=${IPKG_INSTROOT:-}
+export IPKG_INSTROOT
+
+. /lib/functions.sh
+. /lib/mwan3/mwan3.sh
+
+set -e
+
+mwan3_init
+
+sanitize_route()
+{
+	printf '%s\n' "$1" | sed -ne "$MWAN3_ROUTE_LINE_EXP"
+}
+
+expected='192.0.2.0/24 dev eth0 scope link src 192.0.2.1 '
+
+for flags in 'dead linkdown' 'linkdown dead' 'dead' 'linkdown'; do
+	actual=$(sanitize_route "$expected$flags")
+	[ "$actual" = "$expected" ] || {
+		echo "failed to sanitize route flags: $flags" >&2
+		echo "expected: '$expected'" >&2
+		echo "actual:   '$actual'" >&2
+		exit 1
+	}
+done
+
+ipv6_route='fd00:1::/64 via fe80::dead dev eth0 proto static metric 1024 pref medium'
+actual=$(sanitize_route "$ipv6_route")
+[ "$actual" = "$ipv6_route" ] || {
+	echo "failed to preserve an IPv6 address ending in dead" >&2
+	echo "expected: '$ipv6_route'" >&2
+	echo "actual:   '$actual'" >&2
+	exit 1
+}