Munin contributed plugins

#!/bin/sh

#

# Show current signal strength and noise for all connected peers of wifi devices.

# This plugin is suitable for wifi interfaces with a stable selection of peers

# (e.g. infrastructure).

# Author: Lars Kruse, devel@sumpfralle.de

# License: GPL v3 or later

#

# Requirements:

#  * "iwinfo" tool (alternatively: fall back to "iw" - with incomplete data)

#  * root privileges (for "iw" and "iwinfo")

#

# Magic markers

#%# capabilities=autoconf suggest

#%# family=auto

set -eu

# prefer "iwinfo" for information retrieval, if it is available

if which iwinfo >/dev/null; then

	# "iwinfo" has a stable output format but is only available on openwrt

	get_wifi_interfaces() { iwinfo | grep "^[a-zA-Z]" | awk '{print $1}'; }

	# return MAC of peer and the signal strength

	get_wifi_peers() { iwinfo "$1" assoclist | grep "^[0-9a-fA-F]" | awk '{print $1,$2}'; }

	# the noise should be the same for all peers

	get_wifi_noise() { iwinfo "$1" info | sed -n 's/^.* Noise: \([0-9-]\+\).*/\1/p'; }

else

	# "iw" is available everywhere - but its output format is not recommended for non-humans

	get_wifi_interfaces() { iw dev | awk '{ if ($1 == "Interface") print $2; }'; }

	get_wifi_peers() { iw dev wlan0 station dump \

		| awk '{ if ($1 == "Station") mac=$2; if (($1 == "signal") && ($2 == "avg:")) print mac,$3}'; }

	# TODO: there seems to be no way to retrieve the noise level via "iw"

	get_wifi_noise() { echo; }

fi

clean_fieldname() {

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

}

get_ip_for_mac() {

	local ip

	ip=$(arp -n | grep -iw "$1$" | awk '{print $1}' | sort | head -1)

	[ -n "$ip" ] && echo "$ip" && return 0

	# no IP found - return MAC instead

	echo "$1"

}

get_wifi_device_from_suffix() {

	local suffix

	local real_dev

	# pick the part after the basename of the real file

	suffix=$(basename "$0" | sed "s/^$(basename "$(readlink "$0")")//")

	for real_dev in $(get_wifi_interfaces); do

		[ "$suffix" != "$(clean_fieldname "$real_dev")" ] || echo "$real_dev"

	done | head -1

}

ACTION="${1:-}"

case "$ACTION" in

	config)

		wifi=$(get_wifi_device_from_suffix)

		echo "graph_title Wireless signal quality - $wifi"

		echo "graph_args --upper-limit 0"

		echo "graph_vlabel Signal and noise [dBm]"

		echo "graph_category network"

		echo "graph_info This graph shows the signal and noise for all wifi peers"

		echo "noise.label Noise floor"

		echo "noise.draw LINE"

		# sub graphs for all peers

		get_wifi_peers "$wifi" | while read mac signal; do

			fieldname=$(clean_fieldname "peer_${mac}")

			peer=$(get_ip_for_mac "$mac")

			echo "signal_${fieldname}.label $peer"

			echo "signal_${fieldname}.draw LINE"

		done

		;;

	autoconf)

		[ -z "$(get_wifi_interfaces)" ] && echo "no (no wifi interfaces found)" && exit 1

		echo "yes"

		;;

	suggest)

		get_wifi_interfaces | while read ifname; do

			clean_fieldname "$ifname"

		done

		;;

	"")

		wifi=$(get_wifi_device_from_suffix)

		peer_data=$(get_wifi_peers "$wifi")

		echo "$peer_data" | while read mac signal; do

			# ignore empty datasets

			[ -z "$signal" ] && continue

			fieldname=$(clean_fieldname "peer_${mac}")

			echo "signal_${fieldname}.value $signal"

		done

		echo "noise.value $(get_wifi_noise "$wifi")"

		;;

	*)

		echo >&2 "Invalid action (valid: config)"

		echo >&2

		;;

esac