#!/bin/sh
set -e

. /usr/share/debconf/confmodule

INTERFACES=$(grep : /proc/net/dev | cut -d':' -f1 | sort | sed -e 's/ *//' | grep -E '^(en|eth|nas|tap|nic-)')
db_get ppp/interface
PPPOE="$RET"
db_capb backup

log() {
	logger -t DEBUG:ppp-udeb $*
}

fail() {
	logger -t FAIL:ppp-udeb $*
}

ppp_concentrator_on() {
	db_subst ppp/detect_progress IFACE "${1}" || true
	if [ -z "$(ip link show $1 up)" ]; then
		log "$1 was not configured. ppp-udeb will bring it up"
		PPPUP=yes
		ip link set $1 up
	else
		log "$1 was already up"
		PPPUP=no
	fi
	MAXWAIT=20; IW=5; TOTWAIT=$(($MAXWAIT + $MAXWAIT + $IW))
	R=0
	db_progress START 0 $TOTWAIT ppp/detect_progress
	for P in "" "-U" ; do
		rm -f /tmp/probe-finished /tmp/ppp-errors
		( R=$(pppoe-discovery -A $P -I $1 2>/tmp/ppp-errors | \
			grep AC | wc -l)
		  echo $R > /tmp/probe-finished ) &
		WAIT=0
		TO=0

		while [ ! -f /tmp/probe-finished ]; do
			log "Timeout detected $TO"
			sleep 1
			db_progress STEP 1
			WAIT=$(($WAIT + 1))
			if [ $WAIT -ge $MAXWAIT ]; then
				touch /tmp/probe-finished
			fi
			TO=$(grep Timeout /tmp/ppp-errors 2>/dev/null | wc -l || true)
			if [ $TO -eq 1 ]; then
				touch /tmp/probe-finished
				break
			fi
			log "pppoe probe output size: $(cat /tmp/probe-finished 2> /dev/null)"
		done
		R=$(cat /tmp/probe-finished 2>/dev/null || true)
		if [ -n "$R" -a 1$R -ne 10 ]; then
			break
		fi
		if [ -z "$P" ]; then
			sleep $IW
			db_progress STEP $IW
		fi
	done

	PROCESS=$(ps -A | grep pppoe-discovery | sed s:^[[:space:]]::g | \
		  cut -f1 -d' ' || true)
	if [ $TO -ne 1 -a "$PROCESS" ]; then
		kill $PROCESS
	fi
	rm -f /tmp/probe-finished /tmp/ppp-errors
	db_progress STOP

	if [ -n "$R" -a 1$R -ne 10 ]; then
		return 0
	else
		return 1
	fi
}

reset_if_needed() {
	# Bring down an earlier pppoe connection, if there is one
	if [ -e $PIDF ]
	then
		PID=$(cat $PIDF)
		log "found PID file $PIDF which refers to process $PID; searching for the pppd process"
		if [ -z "$(ps | grep "^\s*$PID" | sed "s/^\s*$PID\s.*$/$PID/")" ]
		then
			log "$PID not found; removing pid file"
		else
			log "$PID found; killing it and removing pid file"
			kill $PID || true
		fi
		rm -f $PIDF
	fi

	# Bring down previously raised interface
	if [ "$PPPOE" != "_" ]; then
		ip link set "$PPPOE" down
		db_set ppp/interface "_"
	fi
}

valid_hostname() {
	if [ $(echo -n "$1" | wc -c) -lt 2 ] ||
	   [ $(echo -n "$1" | wc -c) -gt 63 ] ||
	   [ "$(echo -n "$1" | sed 's/[^-\.[:alnum:]]//g')" != "$1" ] ||
	   [ "$(echo -n "$1" | grep "\(^-\|-$\)")" ]; then
		return 1
	fi
	return 0
}

# Sanity check: we rely on some netcfg functionality but cannot depend on it;
# netcfg should always be present, but bail out if it is not
if [ ! -e /bin/netcfg ]; then
	fail "required package netcfg is not installed"
	exit 1
fi

# Bring up the loopback interface
if [ -z "$(ip link show lo up)" ]; then
	ip link set lo up
	ip addr flush dev lo
	ip addr add 127.0.0.1/8 dev lo
fi

if [ -z "$INTERFACES" ]; then
	fail "no Ethernet interfaces detected"
	db_input critical ppp/detect_failed || true
	db_go || true
	exit 1
fi

PIDF=/var/run/ppp-udeb.pid
reset_if_needed

# Test each of the interfaces for a concentrator; stop when one is found
for IFACE in $INTERFACES; do
	if ppp_concentrator_on $IFACE; then
		log "setting pppoe connection on $IFACE"
		db_set ppp/interface $IFACE
		break
	else
		if [ "$PPPUP" = yes ]; then
			log "no concentrator found on $IFACE; will bring the interface back down"
			ip link set $IFACE down
		else
			log "ppp-udeb no concentrator found on $IFACE"
		fi
		IFACE=''
	fi
done

if [ -z "$IFACE" ]; then
	fail "no concentrators detected"
	db_input critical ppp/no_concentrators || true
	db_go || true
	exit 1
fi

db_input high ppp/username || true
db_go || exit 10
db_get ppp/username
USERNAME="$RET"

db_input high ppp/password || true
db_go || exit 10
db_get ppp/password
PASSWORD="$RET"

# Clear answers in case the script is run a second time
db_unregister ppp/password
db_unregister ppp/username


# Ask for the hostname and domainname to use for the system
# (using the netcfg templates!)
while true; do
	db_input high netcfg/get_hostname || [ $? -eq 30 ]
	db_input high netcfg/get_domain || [ $? -eq 30 ]
	db_go || exit 10
	db_get netcfg/get_hostname
	HOSTNAME="$RET"
	if valid_hostname "$HOSTNAME"; then
		db_get netcfg/get_domain
		DOMAINNAME="$RET"
		break
	else
		db_input high netcfg/invalid_hostname || true
		db_fset netcfg/get_hostname seen false
	fi
done


# FIXME: lo snippet should not be ppp-udeb's job
cat > /etc/network/interfaces <<EOF
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# This configuration stanza prevents ifupdown-aware network daemons
# like NetworkManager from managing the interface which is used for
# the PPPoE connection
iface $IFACE inet manual

# PPPoE connection
auto provider
iface provider inet ppp
	pre-up /bin/ip link set $IFACE up
	provider provider
EOF

# Set hostname and create a basic /etc/hosts file
echo "127.0.0.1	localhost" > /etc/hosts

if [ "$HOSTNAME" ]; then
	echo "$HOSTNAME" >/etc/hostname

	if [ "$DOMAINNAME" ]; then
		echo -e "127.0.1.1\t$HOSTNAME.$DOMAINNAME\t$HOSTNAME" >> /etc/hosts
	else
		echo -e "127.0.1.1\t$HOSTNAME" >> /etc/hosts
	fi
fi

cat >> /etc/hosts <<EOF

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
EOF


cat <<EOF > /etc/ppp/peers/provider
# kernel space PPPoE driver configuration
#
# See the manual page pppd(8) for information on all the options.

# MUST CHANGE: Uncomment the following line, replacing the user@provider.net
# by the DSL user name given to your by your DSL provider.
# There should be a matching entry with the password in /etc/ppp/pap-secrets
# and/or /etc/ppp/chap-secrets.
#user "myusername@myprovider.net"
user "$USERNAME"

#linkname provider
#debug

# Load the pppoe plugin. Change the ethernet interface name if needed.
plugin rp-pppoe.so
$IFACE

# Assumes that your IP address is allocated dynamically by the ISP.
noipdefault
# Try to get the name server addresses from the ISP.
usepeerdns
# Use this connection as the default route.
# Comment out if you already have the correct default route installed.
defaultroute

# Make sure that sensitive data does not get into the logs
hide-password

# Peer should be alive
lcp-echo-interval 20
lcp-echo-failure 3

# Makes pppd "dial again" when the connection is lost.
persist

# Do not ask the remote to authenticate.
noauth

# RFC 2516, paragraph 7 mandates that the following options MUST NOT be
# requested and MUST be rejected if requested by the peer:
# Address-and-Control-Field-Compression (ACFC)
noaccomp
# Asynchronous-Control-Character-Map (ACCM)
default-asyncmap

# Do not try to negotiate other kinds of compression.
nopcomp
noccp
novj
EOF

: > /etc/ppp/pap-secrets
chmod 600 /etc/ppp/pap-secrets
cat <<EOF > /etc/ppp/pap-secrets
#GENERATED-BY-DEBIAN-INSTALLER#
"$USERNAME"	*	"$PASSWORD"
EOF
cp /etc/ppp/pap-secrets /etc/ppp/chap-secrets

log-output -t depmod
log-output -t ppp-udeb modprobe pppoe

log-output -t ppp-udeb pppd call provider
sleep 1 # allow forking
PID=`ps | grep 'call provider' | grep pppd | sed 's:\s*\([0-9]*\).*$:\1:g'`
echo $PID > $PIDF

STEP=0
db_progress START 0 31 ppp/please_wait
log "Waiting for message from pppd[$PID]"
while [ "$STEP" -lt 30 ]
do
	ANSWER=$(grep -E "pppd\[$PID\]:.(PAP|CHAP)\ authentication\ (failed|succeeded)" /var/log/syslog | tail -n 1 | sed -e 's:^.*\(failed\).*$:\1:g' -e 's:^.*\(succeeded\).*$:\1:g')
	if [ "$ANSWER" = "succeeded" ] || [ "$ANSWER" = "failed" ]
	then
		STEP=30
		log "got result: authentication $ANSWER"
	else
		log "Answer unknown"
	fi
	sleep 1
	STEP=$(expr $STEP + 1)
	db_progress STEP 1
done
db_progress STOP

if [ "$ANSWER" = "failed" ]; then
	fail "authentication failed"
	(rm -f $PIDF && kill $PID) || true 2> /dev/null
	db_input critical ppp/wrong_login || true
	db_go || true
	exit 1
elif [ -z "$ANSWER" ] && [ "$STEP" -ge 30 ]; then
	fail "unhandled error detected"
	(rm -f $PIDF && kill $PID) || true 2>/dev/null
	db_input critical ppp/unhandled || true
	db_go || true
	exit 1
else
	# Handle a fallback DNS
	if ! [ -s /etc/resolv.conf ] && db_get netcfg/get_nameservers; then
		for nameserver in $RET; do
			echo "nameserver $nameserver" >>/etc/resolv.conf
		done
	fi
fi

exit 0