#!/bin/sh

[ "$VERBOSITY" = 1 ] && set -x

sysfs()
{
	# Called with :
	# $1 = value to write. Won't write if $1 is empty.
	# $2 = basename of the file in bonding/ to write to.
	if [ "$1" ] ; then
		echo "$1" > "/sys/class/net/$IFACE/master/bonding/$2"
		return $?
	fi
	return 0
}

# If the stanza bond-give-a-chance is set for a slave interface,
# then force $IFACE to be the primary for some time, then restore primary to it previous value.

# This stanza is designed to workaround a bug in wpa_supplicant, when used with bonding :

# wpa_supplicant expect wifi authentication packets on the bond interface, but also send wifi authentication packets on the bond interface.
# If the active interface is not the wifi interface at the time wpa_supplicant try to authenticate, the wifi AP won't receive anything, causing the authentication to fail.

# In order for the wifi authentication to succeed, one need to give a chance to the wifi interface to send authentication packets.
# "bond-give-a-chance 10" will set the wifi interface as the primary interface for 10 seconds, then restore the previous primary interface.
# This is supposed to be enought to give a chance to wifi to authenticate properly.

if [ "$IF_BOND_GIVE_A_CHANCE" ] ; then
	read primary < "/sys/class/net/$IFACE/master/bonding/primary"
	# Set the temporary primary.
	sysfs "$IFACE" primary

	# Wait for the link to be setup, but not longer that $IF_BOND_GIVE_A_CHANGE seconds.
	while [ "$IF_BOND_GIVE_A_CHANCE" -gt 0 ] ; do
		if ip link show $IFACE | grep -sq 'state UP'; then
			break
		fi
		sleep 1
		IF_BOND_GIVE_A_CHANCE=`expr $IF_BOND_GIVE_A_CHANCE - 1`
	done
		
	# Restore the previous primary.
	sysfs "$primary" primary
fi