Munin contributed plugins

#!/bin/sh

#

# Monitor the wifi channel occupation (taken from "iw dev wlan0 survey dump").

#

# Symlink this plugin with the name of the wifi interface added (e.g. "wlan0").

#

#

# Copyright (C) 2015 Lars Kruse <devel@sumpfralle.de>

#

#    This program is free software: you can redistribute it and/or modify

#    it under the terms of the GNU General Public License as published by

#    the Free Software Foundation, either version 3 of the License, or

#    (at your option) any later version.

#

#    This program is distributed in the hope that it will be useful,

#    but WITHOUT ANY WARRANTY; without even the implied warranty of

#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

#    GNU General Public License for more details.

#

#    You should have received a copy of the GNU General Public License

#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

#

# Magic markers

#%# capabilities=autoconf suggest

#%# family=auto

set -eu

SCRIPT_PREFIX="wireless_channel_occupation_"

clean_fieldname() {

	echo "$1" | sed 's/^\([^A-Za-z_]\)/_\1/; s/[^A-Za-z0-9_]/_/g'

}

get_wifi_devices() {

	iw dev | grep Interface | awk '{print $2}'

}

get_wifi_device_from_suffix() {

	local suffix

	local called

	called=$(basename "$0")

	suffix="${called#$SCRIPT_PREFIX}"

	# empty result if the prefix did not match (and was not removed)

	[ "$suffix" = "$0" ] && echo "" || echo "$suffix"

}

if [ "${1:-}" = "autoconf" ]; then

	if which iw 2>/dev/null; then

		if [ -n "$(get_wifi_devices)" ]; then

			echo "yes"

		else

			echo "no (missing wifi devices)"

		fi

	else

		echo "no (missing 'iw' dependency)"

	fi

elif [ "${1:-}" = "suggest" ]; then

	get_wifi_devices

elif [ "${1:-}" = "config" ]; then

	device=$(get_wifi_device_from_suffix)

	[ -z "$device" ] && echo >&2 "Invalid wifi device name given" && exit 1

	echo "graph_title Channel Occupation of $device"

	echo "graph_vlabel %"

	echo "graph_category wireless"

	echo "graph_args --base 1000 -r --lower-limit 0 --upper-limit 100"

	dev_field=$(clean_fieldname "$device")

	# active: listening time on this channel (usually: 5 minutes = 300000ms)

	echo "${dev_field}_active.label Transmit"

	echo "${dev_field}_active.type DERIVE"

	echo "${dev_field}_active.graph no"

	# busy = receive + transmit + unknown

	echo "${dev_field}_busy.label unknown"

	echo "${dev_field}_busy.type DERIVE"

	echo "${dev_field}_busy.draw AREA"

	echo "${dev_field}_busy.cdef 100,1,${dev_field}_active,${dev_field}_busy,${dev_field}_receive,${dev_field}_transmit,+,-,/,/,*"

	# receive: this radio receives traffic for itself

	echo "${dev_field}_receive.label Receive"

	echo "${dev_field}_receive.type DERIVE"

	echo "${dev_field}_receive.draw STACK"

	echo "${dev_field}_receive.cdef 100,${dev_field}_receive,${dev_field}_active,/,*"

	# transmit: this radio transmits traffic

	echo "${dev_field}_transmit.label Transmit"

	echo "${dev_field}_transmit.type DERIVE"

	echo "${dev_field}_transmit.draw STACK"

	echo "${dev_field}_transmit.cdef 100,${dev_field}_transmit,${dev_field}_active,/,*"

else

	device=$(get_wifi_device_from_suffix)

	[ -z "$device" ] && echo >&2 "Invalid wifi device name given" && exit 1

	iw dev "$device" survey dump \

		| grep -F -A 5 "[in use]" \

		| grep -E "channel (busy|receive|transmit|active) time:" \

		| awk '{print "'${device}_'"$2"'.value'",$4}'

fi

exit 0