Munin contributed plugins

#!/bin/sh

: << =cut

=head1 NAME

wireless_signal_noise_ - Show signal strength and noise for all connected peers of wifi interface

=head1 APPLICABLE SYSTEMS

This plugin is suitable for wifi interfaces with a stable selection of peers (e.g. infrastructure).

It is probably not useful for hotspot-like scenarios.

Information is parsed from the output of the tool "iwinfo" (OpenWrt) or "iw" (most systems,

incomplete information).

=head1 CONFIGURATION

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

Root permissions are probably required for accessing "iw".

  [wireless_signal_noise_*]

  user root

=head1 VERSION

  1.1

=head1 AUTHOR

Lars Kruse <devel@sumpfralle.de>

=head1 LICENSE

GPLv3 or above

=head1 MAGIC MARKERS

  #%# family=auto

  #%# capabilities=autoconf suggest

=cut

set -eu

SCRIPT_PREFIX="wireless_signal_noise_"

# 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

if which arp >/dev/null; then

	# openwrt does not provide 'arp' by default

	get_arp() { arp -n; }

else

	get_arp() { cat /proc/net/arp; }

fi

clean_fieldname() {

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

}

get_ip_for_mac() {

	local ip

	ip=$(get_arp | 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 "$0" | sed "s/^$SCRIPT_PREFIX//")

	for real_dev in $(get_wifi_interfaces); do

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

	done | head -1

}

do_config() {

	local wifi

	wifi=$(get_wifi_device_from_suffix)

	[ -z "$wifi" ] && echo >&2 "Missing wifi: $wifi" && return 1

	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 -r 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

}

do_fetch() {

	local wifi

	local peer_data

	local noise

	wifi=$(get_wifi_device_from_suffix)

	[ -z "$wifi" ] && echo >&2 "Missing wifi: $wifi" && return 1

	peer_data=$(get_wifi_peers "$wifi")

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

		# ignore empty datasets

		[ -z "$signal" ] && continue

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

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

	done

	noise=$(get_wifi_noise "$wifi")

	echo "noise.value ${noise:-U}"

}

ACTION="${1:-}"

case "$ACTION" in

	config)

		do_config || exit 1

		if [ "${MUNIN_CAP_DIRTYCONFIG:-0}" = "1" ]; then do_fetch; fi

		;;

	autoconf)

		if [ -z "$(get_wifi_interfaces)" ]; then

			echo "no (no wifi interfaces found)"

		else

			echo "yes"

		fi

		;;

	suggest)

		get_wifi_interfaces | while read -r ifname; do

			clean_fieldname "$ifname"

		done

		;;

	"")

		do_fetch

		;;

	*)

		echo >&2 "Invalid action (valid: config / suggest / autoconf / <empty>)"

		echo >&2

		exit 2

		;;

esac