#!/bin/sh
#
# Check if this system (still) should be an active B.A.T.M.A.N. gateway
# and update gw_mode accordingly if necessary (Salt managed)
#
# Rewritten by: Maximilian Wilhelm <max@sdn.clinic>
#  -- Sat, 07 Mar 2015 23:21:53 +0100
#

node_status_file="/etc/freifunk/status"

# Default to "off"
new_state="off"
force_offline="false"

#
# If the status of this machine is not 'active', we should not
# be an active gateway.
if [ -f "${node_status_file}" ]; then
	status=$(cat "${node_status_file}")
	if [ "${status}" != "active" ]; then
		force_offline="true"
	fi
fi

#
# If there is no DHCP server running here, we should not be an
# active gateway.
if ! systemctl status isc-dhcp-server >/dev/null 2>&1; then
	force_offline="true"
fi

#
# 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

#
# Forcefully offline?
if [ "${force_offline}" = "true" ]; then
	new_state="off"
fi

#
# Compatiblity glue: Newer versions of batctl print a deprecation
# warning when called with -m <batif>. Avoid spamming the log and
# producting SPAM by silently handling this here.
mesh_if_param="-m"
if batctl -h 2>&1 | grep -q "meshif"; then
	mesh_if_param="meshif"
fi

#
# Let's check the interfaces
for iface in $(ip -br l | awk '/^bat-/ { print $1 }'); do
	# Ignore any external BATMAN instance, if present
	if echo "${iface}" | grep -q '-ext$'; then
		continue
	fi

	old_state="$(batctl "${mesh_if_param}" "${iface}" gw_mode | awk '{ print $1 }')"
	if [ "$old_state" = "$new_state" ]; then
		# Nothing to do here, carry on
		continue
	fi

	# Set new values
	batctl "${mesh_if_param}" "${iface}" gw_mode "${new_state}"
	logger "B.A.T.M.A.N. gateway mode changed from ${old_state} to ${new_state} on ${iface}"
done