#!/bin/sh
#
#   FILE: wlanscanner
# AUTHOR: Adalbert Prokop <adalbert.prokop@gmx.de>
#   DATE: 25. August 2007
#
# Copyright (C) 2005 Adalbert Prokop <adalbert.prokop@gmx.de>
# All rights reserved.
#
# 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 2 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, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#set -x # debug

if [ $UID != 0 ]; then
	/usr/bin/sudo /usr/local/bin/$(basename $0) "$@"
	exit $?
fi
PATH=/sbin:/bin:/usr/bin:/usr/sbin:/usr/local/sbin:/usr/local/bin:$PATH
LANG=C
export PATH LANG

# date >> /tmp/wlanscanner # debug

declare -i i
declare -i max
declare -i len
declare -i DEBUG
declare -a ADDRESS
declare -a ESSID
declare -a MODE
declare -a LEVEL
declare -a ENC

POSSIBLE_IFACES="ath0 wlan0 eth1"
IFACE=
USERSEL=
PREF_WLAN=
PREF_NETS=/etc/sysconfig/preferred_wlans
WIRELESSOPTS=/etc/pcmcia/wireless.opts
LOGFILE=/var/log/wlanscanner.log
DEBUG=0

function usage() {
	cat <<EOF
Usage: $(basename $0) [{-i|--interface} <interface>] <network>

This script scans for available wireless networks, chooses one with strongest
signal from a list of preferred networks. If the optional parameter <network> is
given, the magic of autodetection is not performed. Instead the given <network>
will be set. This is useful for weak network, ad-hoc networks in presence of
other wireless networks or "hidden" networks, which are not broadcasting their
ESSID.

Options:
	-i, --interface
	All scanning will happen on this interface. If ommited, the first active
	interfaces among $POSSIBLE_IFACES will be used.

<network> is a network definition as given in $WIRELESSOPTS. If not given,
the air is scanned for available networks and the strongest one specified in
$PREF_NETS will be used.

FILES
	$PREF_NETS
	A list with known, preferred wireless network ESSIDs, one per line.

	$WIRELESSOPTS
	This file will be sourced. It contains specifications for each wireless
	network. The name of the configuration section may differ from the
	ESSID, but only for those network which will be selected manually.
	It has the form "name,MAC"

	Format:
	case "\$PREF_WLAN" in
	
	MyWLAN,*)
	INFO="Test net"
	ESSID="testnet"
	MODE="Managed"
	KEY="s:1111111111111"
	;;
	
	...
	...
	...
	esac

EOF
}

# parse command line args
eval set -- $(getopt -o i: -l interface: -- "$@")
if [ "$?" -ne 0 ]; then
        usage
        echo "Exiting because of previous errors." >&2
        exit 1
fi

while [ "$1" != "--" ]; do
        case "$1" in
                -i|--interface)
			IFACE="$2"
                        shift 2
                        ;;
	esac
done
shift

USERSEL="$1"

if [ $DEBUG != 0 ]; then
	exec 3>>$LOGFILE
	exec 1>&3
	exec 2>&3
	date
	echo "$@"
	echo ---
	env
	echo ---
	which iwconfig
	which iwlist
	which sudo
	echo ---
	cat $PREF_NETS
	echo ---
	cat $WIRELESSOPTS
	echo ---
	set -x
fi

if [ ! -f $PREF_NETS ]; then
	echo "Es gibt keine Datei $PREF_NETS mit bevorzugten Netzen!"
	exit 1
fi

if [ ! -f $WIRELESSOPTS ]; then
	echo "Es gibt keine Datei $WIRELESSOPTS mit Netzwerkparametern!"
	exit 1
fi

if [ -n "$HAL_PROP_NET_INTERFACE" ]; then
	# we are called from HAL!
	IFACE=$HAL_PROP_NET_INTERFACE
fi

if [ -z "$IFACE" ]; then
	echo -n "No network interface given. "
	IPSHOW="$(ip link show)"
	for if in $POSSIBLE_IFACES; do
		if echo "$IPSHOW" | grep -q "\<${if}\>"; then
			IFACE=$if
			echo "Interface set to $IFACE"
			break
		fi
	done
fi

# activate interface before scanning
ifconfig $IFACE up

# scan three times and wait three seconds between each scan
SCAN_RESULT=
i=0
while [ $i -lt 3 -a -z "$SCAN_RESULT" ]; do
	sleep 3 # be nice...
	SCAN_RESULT="$(iwlist $IFACE scanning|grep -v "No scan results")"
	i=$(($i+1))
done

# the magic of autodetection is required if and only if
# - we have a file with preferred nets
# - the user does not select a net manually
if [ -s $PREF_NETS -a -z "$USERSEL" ]; then
	i=-1
	while read line; do
		KEY=$(echo $line|cut -d: -f1)
		case $KEY in
			Cell*)
				i=$(($i+1))
				ADDRESS[$i]=$(echo $line|cut -d: -f 2-|tr -d " ")
				;;
			ESSID)
				eval ESSID[$i]=$(echo $line|cut -d: -f 2) ;;
			Mode)
				MOD=$(echo $line|cut -d: -f 2)
				if [ $MOD == Master ]; then
					MODE[$i]=Managed
				else
					MODE[$i]=$MOD
				fi
				;;
			*"Signal level"*)
				LEVEL[$i]="$(echo "$line"|sed -e 's/.*Signal level=\(-[0-9]\+\).*/\1/g')"
				;;
			Encrypt*)
				ENC[$i]=$(echo $line|cut -d: -f 2) ;;
		esac
	done <<EOF
$SCAN_RESULT
EOF

	# Counter unchanged. No nets found.
	if [ $i == -1 ]; then
		echo "No WLANs found. Exiting."
		exit 0
	fi
	
	i=0
	len=${#ESSID[@]}
	while [ $i -lt $len ]; do
		# mark not matching entries by erasing the ESSID
		grep -q "^${ESSID[$i]}\$" $PREF_NETS || unset ESSID[$i]
		i=$(($i+1))
	done
	
	
	# find maximal strength net
	max=-1
	i=0
	while [ $i -lt $len ]; do
		if [ -n "${ESSID[$i]}" ]; then
			if [ $max == -1 ]; then
				max=$i
			else
				if [ ${LEVEL[$i]} -gt ${LEVEL[$max]} ]; then
					max=$i
				fi
			fi
		fi
		i=$(($i+1))
	done

	if [ $max == -1 ]; then
		echo "No desired WLAN has been found. Exiting."
		exit 0
	fi

	PREF_WLAN="${ESSID[$max]},${ADDRESS[$max]}"
	KEY=${ENC[$max]} 
	# end of magic ;-)
elif [ ! -s $PREF_NETS -a -z "$USERSEL" ]; then
	echo "$PREF_NETS has zero size!"
	exit 1
else
	echo "No auto-detection."
	PREF_WLAN="$USERSEL,"
fi

KEY=
ESSID=
NICK=
MODE=

. $WIRELESSOPTS

if [ -n "$IWPRIV" ]; then
	echo "Setting iwpriv mode for $IFACE to $IWPRIV"
	iwpriv $IFACE $IWPRIV
	sleep 1
fi

echo "Setting WLAN card $IFACE to node $ESSID in $MODE mode."
iwconfig $IFACE essid "$ESSID" ${MODE:+mode $MODE} ${NICK:+ nick $NICK} ${KEY:+key $KEY}

if [ -n "$IWPRIV" ]; then
	iwpriv $IFACE $IWPRIV
fi

if [ "$WPA" = "yes" ]; then
	[ -f /var/run/wpa_supplicant-wlanscanner.pid ] && kill $(cat /var/run/wpa_supplicant-wlanscanner.pid)
	sleep 2
	/usr/sbin/wpa_supplicant -B -w -c /etc/wpa_supplicant/wpa_supplicant.conf -i $IFACE ${WPADRIVER:+-D $WPADRIVER} -P /var/run/wpa_supplicant-wlanscanner.pid 
fi

if [ "$DHCP" == "yes" ]; then
	[ -f /var/run/dhclient-wlanscanner.pid ] && kill $(cat /var/run/dhclient-wlanscanner.pid)
	sleep 2
	dhclient -pf /var/run/dhclient-wlanscanner.pid $IFACE
	DHCP_RETVAL=$?
elif [ -n "$IP" ]; then
	ifconfig $IFACE $IP ${NETMASK:+netmask} $NETMASK $IFCONFIG_OPTS
	[ -n "$GATEWAY" ] && route add -net default gw $GATEWAY dev $IFACE
fi

if [ $DEBUG != 0 ]; then
	exec 3>&-
fi