Munin contributed plugins

#!/bin/sh

: << =cut

=head1 NAME

wireless_signal_ranges_ - Group and count all connected wifi peers by signal strength ranges

=head1 APPLICABLE SYSTEMS

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

This plugin is suitable for wifi interfaces with a variable selection of peers (e.g. mobile

clients).

=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_ranges_*]

  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_ranges_"

# thresholds for signal quality ranges: ascending values

SIGNAL_THRESHOLDS="-88 -80 -60 0"

# 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 $2}'; }

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 == "signal") && ($2 == "avg:")) print $3}'; }

fi

clean_fieldname() {

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

}

get_level_fieldname() {

	echo "range_${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

	local lower

	wifi=$(get_wifi_device_from_suffix)

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

	echo "graph_title Wireless signal quality ranges - $wifi"

	echo "graph_args --upper-limit 0"

	echo "graph_vlabel Signal ranges"

	echo "graph_category network"

	echo "graph_info This graph shows numbers of peers with defined wifi signal ranges"

	lower="noise"

	for level in $SIGNAL_THRESHOLDS; do

		fieldname=$(get_level_fieldname "$level")

		echo "${fieldname}.label $lower...$level"

		echo "${fieldname}.draw AREASTACK"

		lower="$level"

	done

}

do_fetch() {

	local wifi

	local peer_data

	local previous_count

	local current_count

	local fieldname

	wifi=$(get_wifi_device_from_suffix)

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

	peer_data=$(get_wifi_peers "$wifi")

	previous_count=0

	for level in $SIGNAL_THRESHOLDS; do

		current_count=$(echo "$peer_data" | awk '

			BEGIN { count=0; }

			{ if (($1 != "") && ($1 <= '"$level"')) count++; }

			END { print count; }')

		fieldname=$(get_level_fieldname "$level")

		echo "${fieldname}.value $((current_count - previous_count))"

		previous_count="$current_count"

	done

}

ACTION="${1:-}"

case "$ACTION" in

	config)

		do_config || exit 1

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

		;;

	autoconf)

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

		echo "yes"

		;;

	suggest)

		get_wifi_interfaces | while read -r ifname; do

			clean_fieldname "$ifname"

		done

		;;

	"")

		do_fetch

		;;

	*)

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

		echo >&2

		exit 2

		;;

esac