#!/bin/bash

# Scriptname:       network-discovery
# Intention:		Try to find some kind of network connection providing a link to
#					the internet. For this a list of wired interfaces is checked first.
#					Afterwards a list of wireless devices is checked whereas a list of 
#					provided ESSIDs is prefered for the connection. 
#					Optionally the script also tries to connect to whatever ESSID it can find
#					to get a connection (-> ESSID 'any' ).
# Version:			0.1		(3.11.2007)
# 					0.2		(5.11.2007)
#						- added several sleeps
#						- implemented 5 retries to get the interface up with ifconfig $IF up
#						- added a complete shutdown of all involved network interfaces at startup to get a clean start


#####################
# open improvements #
#####################

# FIXME Log error/status messages via syslog --> logger
# FIXME Trying DHCP on a network without DHCP takes an awfully long time until it aborts
# FIXME Think of something better to test network connectivity 
# FIXME Add generic VPN support
# FIXME check if the tun module is loaded when using VPN
# FIXME Check if all used tools are installed before starting anything
# FIXME Add static configuration support
# FIXME Check output of dhclient for what really happened 
#		success + received ip:
#			DHCPACK from 192.168.0.2
#			bound to 192.168.0.245 -- renewal in 1636 seconds.
#		no success:
#			No DHCPOFFERS received.
# FIXME dhclient processes stay in background after trying to get an ip unsuccessfully (-> quick solution: killall at the end of the file)
# FIXME hidden ESSIDs are not reconized (-> fix: first set the adapter's ESSID then scan for it)


####################
# global variables #
####################

# config for wired network interface
IF_WIRED_LIST="eth0"


# config for wireless network interface
IF_WIRELESS_LIST="ath0"
#IF_WIRELESS_ESSID_LIST="FAU-VPN HOME any"		# adding 'any' to the list also tries to connect through other WLANs in range
IF_WIRELESS_ESSID_LIST="FAU-VPN HOME"		# adding 'any' to the list also tries to connect through other WLANs in range

# OpenVPN config for FAU-VPN
FAU_VPN_PATH="/root/scripts/network/RRZE"


# set delimiter to \n
#IFS="\n"
IFS=" "



#############
# functions #
#############

# test routine for network/internet setup
function check_network_connection {
	echo -ne "\t\tChecking for a working internet connection ... "

	host -W1 google.com 1>/dev/null 2>&1
	EXIT_STATUS=$?

	if ( test $EXIT_STATUS = 127 )
	then
		# command not found
		echo -ne "error\n\t\tCommand 'host' was not found.\nExiting.\n"
		exit 127
	fi

	if ( test $EXIT_STATUS = 1 )
	then
		# no connectivity -> do nothing
		echo -ne "none found.\n"
	fi

	if ( test $EXIT_STATUS = 0 )
	then
		# YEEHA! - got a connection
		echo -ne "OK\n\nSuccess.\n"
		exit 0
	fi
}


##########
# script #
##########

# do a pre-check
#echo -ne "--> Pre-check\n\to connectivity\n"
#check_network_connection;



# FIXME
# shutdown all network related stuff
for IF in $IF_WIRED_LIST
do
	ifconfig $IF down 1>/dev/null 2>&1
done

for IF in $IF_WIRELESS_LIST
do
	ifconfig $IF down 1>/dev/null 2>&1
done

killall dhclient 1>/dev/null 2>&1
killall openvpn 1>/dev/null 2>&1



###### WIRED INTERFACES
echo -ne "\n### WIRED INTERFACES ###\n"
for IF_WIRED in $IF_WIRED_LIST
do
	# check cable connections first
	echo -ne "\n--> Trying interface ${IF_WIRED} ...\n"

	# check if interface exists
	echo -ne "\to existence\n"
	if !( test -e /sys/class/net/${IF_WIRED} ) 
	then
		# interface does not exist -> skip
		echo -ne "\t\tInterface ${IF_WIRED} not found- skipping\n"
		continue
	fi
	echo -ne "\t\tOK\n"


	# check interface state (up/down)
	echo -ne "\to state\n"
	IF_OPERSTATE=`cat /sys/class/net/${IF_WIRED}/operstate`
	echo -ne "\t\t/sys/class/net/${IF_WIRED}/operstate: ${IF_OPERSTATE}\n"
	if ( test "${IF_OPERSTATE}" = "down" )
	then
		# interface is down
		echo -ne "\t\tTrying to 'ifconfig ${IF_WIRED} up' ... "
		
		for i in 1 2 3 4 5
		do 
			echo -ne "#${i} "
			ifconfig ${IF_WIRED} up 1>/dev/null 2>&1
			sleep 1
			IF_OPERSTATE=`cat /sys/class/net/${IF_WIRED}/operstate`
			if ( test "${IF_OPERSTATE}" != "down" )
			then
				break
			fi
			ifconfig ${IF_WIRED} down 1>/dev/null 2>&1
		done
		
		if ( test "${IF_OPERSTATE}" = "down" )
		then
			# trying to bring up the interface didn't work -> skip
			echo -ne "still down - skipping\n"
			ifconfig ${IF_WIRED} down
			continue
		fi

		echo -ne "OK\n"
	fi
	echo -ne "\t\tOK\n"

	# check if the interface is actually connected to a network
	echo -ne "\to carrier\n"
	IF_CARRIER=`cat /sys/class/net/${IF_WIRED}/carrier`
	EXIT_STATUS=$?

	if ( test $EXIT_STATUS != 0 )
	then
		# if the interface is down reading from /sys/class/net/${IF_WIRED}/carrier results in an error
		echo -ne "\t\tThis is weird. Could not read /sys/class/net/${IF_WIRED}/carrier - skipping\n"
		continue
	fi

	echo -ne "\t\t/sys/class/net/${IF_WIRED}/carrier: ${IF_CARRIER}\n"
	if ( test $IF_CARRIER = 0 ) 
	then
		# device is not connected to a network
		echo -ne "\t\tInterface ${IF_WIRED} is not connected to a network - skipping\n"
		ifconfig ${IF_WIRED} down
		continue
	fi
	echo -ne "\t\tOK\n"


	# try to setup a working network connection
	echo -ne "\to setup\n"


	# try to setup the interface through DHCP
	echo -ne "\t\tTrying 'dhclient ${IF_WIRED}' ... "
	dhclient ${IF_WIRED} 1>/dev/null 2>&1
	EXIT_STATUS=$?

	if ( test $EXIT_STATUS = 0 )
	then
		echo -ne "OK\n"
	else
		echo -ne "error (code ${EXIT_STATUS}) - skipping\n"
		continue
	fi
	
	check_network_connection;
	
	# FIXME
	# if we get to this point there was no connection found so we shut down the tried interface again
	ifconfig ${IF_WIRED} down
	killall dhclient
done



###### WIRELESS INTERFACES
echo -ne "\n### WIRELESS INTERFACES ###\n"
for IF_WIRELESS in $IF_WIRELESS_LIST
do

	echo -ne "\n--> Trying interface ${IF_WIRELESS} ...\n"

	# check if interface exists
	echo -ne "\to existence\n"
	if !( test -e /sys/class/net/${IF_WIRELESS} ) 
	then
		# interface does not exist -> skip
		echo -ne "\t\tInterface ${IF_WIRELESS} not found - skipping\n"
		continue
	fi
	echo -ne "\t\tOK\n"


	# check interface state (up/down)
	echo -ne "\to state\n"
	IF_OPERSTATE=`cat /sys/class/net/${IF_WIRELESS}/operstate`
	echo -ne "\t\t/sys/class/net/${IF_WIRELESS}/operstate: ${IF_OPERSTATE}\n"
	if ( test "${IF_OPERSTATE}" = "down" )
	then
		# interface is down
		echo -ne "\t\tTrying to 'ifconfig ${IF_WIRELESS} up' ... "
		
		for i in 1 2 3 4 5
		do 
			echo -ne "#${i} "
			ifconfig ${IF_WIRELESS} up 1>/dev/null 2>&1
			sleep 1
			IF_OPERSTATE=`cat /sys/class/net/${IF_WIRELESS}/operstate`
			if ( test "${IF_OPERSTATE}" != "down" )
			then
				break
			fi
			ifconfig ${IF_WIRELESS} down 1>/dev/null 2>&1
		done
		
		IF_OPERSTATE=`cat /sys/class/net/${IF_WIRELESS}/operstate`
		if ( test "${IF_OPERSTATE}" = "down" )
		then
			# trying to bring up the interface didn't work -> skip
			echo -ne "still down - skipping\n"
			continue
		fi

		echo -ne "OK\n"
	fi
	echo -ne "\t\tOK\n"


	# get list of available unique ESSIDs
	echo -ne "\to Scan\n"
	echo -ne "\t\tScanning ... "
	ESSID_LIST=`iwlist ath0 scan | grep ESSID | awk -F '"' '{print $2}' | tr '\n' ' ' 2>/dev/null`
	sleep 2
	EXIT_STATUS=$?
	if ( test $EXIT_STATUS = 0 )
	then
		echo -ne "OK\n"	
	else
		echo -ne "error (code ${EXIT_STATUS}) - skipping\n"
		continue
	fi

	IF_WIRELESS_ESSIDs_IN_RANGE=""
	for i in $ESSID_LIST
	do
		DUPLICATE_FOUND=0
		for j in $IF_WIRELESS_ESSIDs_IN_RANGE
		do
			if ( test "$i" = "$j" )
			then
				DUPLICATE_FOUND=1
				break
			fi
		done
		
		if ( test $DUPLICATE_FOUND = 0 )
		then
			if ( test "$IF_WIRELESS_ESSIDs_IN_RANGE" = "")
			then
				IF_WIRELESS_ESSIDs_IN_RANGE="${i}"
			else
				IF_WIRELESS_ESSIDs_IN_RANGE="${IF_WIRELESS_ESSIDs_IN_RANGE} ${i}"
			fi
		fi
	done
	echo -ne "\t\tFound unique ESSIDs: '${IF_WIRELESS_ESSIDs_IN_RANGE}'\n"
	echo -ne "\n"

	# try to find valid ESSIDs in range
	echo -ne "\t\tLooking for valid ESSIDs ...\n"
	TRY_UNKNOWN_ESSIDs=0
	IF_WIRELESS_ESSID_CHECKLIST=""
	for IF_WIRELESS_ESSID in $IF_WIRELESS_ESSID_LIST
	do
		# set a flag if checking unknown ESSIDs is desired
		if ( test "$IF_WIRELESS_ESSID" = "any" )
		then
			TRY_UNKNOWN_ESSIDs=1
			continue
		fi
		
		echo -ne "\t\tChecking ESSID '${IF_WIRELESS_ESSID}' ... "
		IS_IN_RANGE=0

		for i in $IF_WIRELESS_ESSIDs_IN_RANGE
		do
			if ( test "$i" = "$IF_WIRELESS_ESSID" )
			then
				IS_IN_RANGE=1
				break
			fi
		done
		
		if ( test $IS_IN_RANGE = 1 )
		then
			# add found valid ESSID to the 'to-check' - list
			if ( test "$IF_WIRELESS_ESSID_CHECKLIST" = "" ) 
			then
				IF_WIRELESS_ESSID_CHECKLIST="$IF_WIRELESS_ESSID"
			else 
				IF_WIRELESS_ESSID_CHECKLIST="$IF_WIRELESS_ESSID_CHECKLIST $IF_WIRELESS_ESSID"
			fi

			echo -ne "OK\n"
		else
			echo -ne "not in range\n"
		fi
	done

	echo -ne "\n"
	if ( test "$IF_WIRELESS_ESSID_CHECKLIST" = "" ) 
	then
		echo -ne "\t\tNo valid ESSID in range of this interface"
		if ( test $TRY_UNKNOWN_ESSIDs = 0 )
		then
			echo -ne " - skipping\n"
			continue
		else
			echo -ne " - trying unknown ESSIDs\n"	
			
			# add all other ESSIDs in range after the valid ESSIDs to the 'to-check' - list
			for i in $IF_WIRELESS_ESSIDs_IN_RANGE
			do
				for j in $IF_WIRELESS_ESSID_CHECKLIST
				do
					if ( test "$i" = "$j" )
					then
						continue 2	
					fi
				done

				if ( test "$IF_WIRELESS_ESSID_CHECKLIST" = "" ) 
				then
					IF_WIRELESS_ESSID_CHECKLIST="$i"
				else 
					IF_WIRELESS_ESSID_CHECKLIST="$IF_WIRELESS_ESSID_CHECKLIST $i"
				fi
			done
		fi
	fi


	# try to setup a working network connection with one of the found ESSIDs
	echo -ne "\to setup\n"
	for ESSID in $IF_WIRELESS_ESSID_CHECKLIST
	do

		# configure interface for ESSID
		echo -ne "\t\tSwitching interface to ESSID '${ESSID}' ... "
		iwconfig ${IF_WIRELESS} essid ${ESSID}
		EXIT_STATUS=$?
		sleep 2

		if ( test $EXIT_STATUS = 0 )
		then
			echo -ne "OK\n"
		else
			echo -ne "error (code ${EXIT_STATUS}) - skipping\n"
			continue 2
		fi


		# try to setup the interface through DHCP
		echo -ne "\t\tTrying 'dhclient ${IF_WIRELESS}' ... "
		dhclient ${IF_WIRELESS} 1>/dev/null 2>&1
		EXIT_STATUS=$?

		if ( test $EXIT_STATUS = 0 )
		then
			echo -ne "OK\n"
		else
			echo -ne "error (code ${EXIT_STATUS}) - skipping\n"
			continue
		fi
		
		
		# FIXME
		# connect through FAU's OpenVPN tunnel
		if ( test "$ESSID" = "FAU-VPN" )
		then
			echo -ne "\t\tConnecting through FAU's OpenVPN tunnel ... "
			PWD=`pwd`
			cd $FAU_VPN_PATH
			openvpn --config RRZE-full-tunnel.ovpn --auth-user-pass secret --daemon FAU-VPN 1>/dev/null 2>&1
			EXIT_STATUS=$?
			cd $PWD
			if ( test $EXIT_STATUS = 0 )
			then
				echo -ne "OK\n"
			else
					echo -ne "error (code ${EXIT_STATUS}) - skipping\n"
					continue 2
			fi
		fi

		check_network_connection;
		
		echo -ne "\n"
	done

done

# unsuccessful exit
killall dhclient # FIXME
echo -ne "\nGiving up.\n"
exit 1