mwan3: prefer default route source address

Prefer the source address from the interface default route before falling
back to the interface address from netifd.

This fixes diagnostics and tracking in setups where the route-selected
source address differs from the interface address.

Fixes: #29055
Signed-off-by: Dharmik Parmar <dharmikparmar2004@yahoo.com>

Author: dhrm1k

net/mwan3/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=mwan3
 PKG_VERSION:=2.12.1
-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

@@ -54,7 +54,7 @@ mwan3_get_true_iface()
 
 mwan3_get_src_ip()
 {
-	local family _src_ip interface true_iface device addr_cmd default_ip IP sed_str
+	local family _src_ip interface true_iface device addr_cmd default_ip IP sed_str route_target
 	interface=$2
 	mwan3_get_true_iface true_iface $interface
 
@@ -64,15 +64,19 @@ mwan3_get_src_ip()
 		addr_cmd='network_get_ipaddr'
 		default_ip="0.0.0.0"
 		sed_str='s/ *inet \([^ \/]*\).*/\1/;T;p;q'
+		route_target="0.0.0.0"
 		IP="$IP4"
 	elif [ "$family" = "ipv6" ]; then
 		addr_cmd='network_get_ipaddr6'
 		default_ip="::"
 		sed_str='s/ *inet6 \([^ \/]*\).* scope.*/\1/;T;p;q'
+		route_target="::"
 		IP="$IP6"
 	fi
 
-	$addr_cmd _src_ip "$true_iface"
+	__network_ifstatus _src_ip "$true_iface" ".route[@.target='$route_target'].source" "" 1
+	[ -n "$_src_ip" ] && _src_ip="${_src_ip%%/*}"
+	[ -z "$_src_ip" ] && $addr_cmd _src_ip "$true_iface"
 	if [ -z "$_src_ip" ]; then
 		if [ "$family" = "ipv6" ]; then
 			# on IPv6-PD interfaces (like PPPoE interfaces) we don't
@@ -98,8 +102,8 @@ mwan3_get_src_ip()
 			fi
 		fi
 		if [ -z "$_src_ip" ]; then
-			network_get_device device $true_iface
-			_src_ip=$($IP address ls dev $device 2>/dev/null | sed -ne "$sed_str")
+			network_get_device device "$true_iface"
+			_src_ip=$($IP address ls dev "$device" 2>/dev/null | sed -ne "$sed_str")
 		fi
 		if [ -n "$_src_ip" ]; then
 			LOG warn "no src $family address found from netifd for interface '$true_iface' dev '$device' guessing $_src_ip"