#!/bin/bash
#
# Check if this system (still) is a gateway and update mesh mode if necessary (Salt managed)
#
# Rewritten by: Maximilian Wilhelm <max@rfc2324.org>
#  -- Sat, 07 Mar 2015 23:21:53 +0100
#

# Default to "off"
new_state="off"

#
# If there is a default route via an IP from our address space
# we assume that this gateway has an internet connection. As a
# default route would be propagated in via iBGP and/or OSPF it
# will only be present if at least one border router has an up
# and running connection to AS201701.
if ip route show | grep "^default via 10.132." -q; then
        new_state="server"
fi

# Make sure the following glob isn't interpreted as a literal string if there isn't
# any meshable interface.
shopt -s nullglob
for mesh_int in /sys/class/net/*/mesh; do
	ifname=$(IFS="/";set -- ${mesh_int};printf "$5\n")
	# Ignore any external BATMAN instance, if present
	if echo "${ifname}" | grep -q '-ext$'; then
		continue
	fi

	if [ "${new_state}" == "off" -a "$(tail -n 1 /sys/kernel/debug/batman_adv/${ifname}/gateways)" == "No gateways in range ..." ] ; then
		logger "No other B.A.T.M.A.N. gateways present, forcing gateway mode to server on ${ifname}"
		new_state="server"
	fi

	old_state="$(cat ${mesh_int}/gw_mode)"
	[ "$old_state" == "$new_state" ] && continue

	echo "${new_state}"  > "${mesh_int}/gw_mode"
	echo "54MBit/54MBit" > "${mesh_int}/gw_bandwidth"
	logger "B.A.T.M.A.N. gateway mode changed from ${old_state} to ${new_state} on ${ifname}"
done