#!/bin/sh -e

. /usr/share/debconf/confmodule
test $DEBIAN_SCRIPT_DEBUG && set -v -x


# List all the interfaces which are UP in the system
list_interfaces() {
    interface_list=""
    if [ -x "$(command -v ip)" ] ; then
        interface_list=`LC_ALL=C ip link show | grep -E '^[0-9]*: ' | grep -v LOOPBACK | grep UP | awk -F: '{print $2}' | sed "s/ //g"`
    else
        if [ -n "$(command -v ifconfig)" ] ; then
            interface_list=`LC_ALL=C ifconfig -a | grep -E '^[a-z0-9]*:' | grep -v LOOPBACK | grep UP | awk -F: '{print $1}' `
        fi
    fi
    # Return with error if the interface list is empty
    if [ -z "$interface_list" ] ; then
        return 1
    fi
    # convert into space separated
    interface_list=`echo $interface_list | sed 's/^\|$//g'` 
    echo $interface_list
    return 0
}


# Count how many interfaces are in the interface_list
count_interfaces() {
    interface_list=$1
    count=`echo $interface_list | sed -e 's/ /\n/g' | wc -l`
    echo $count
    return 0
}

check_interfaces() {
# Check the interface status, abort with error if one is configured but it
# is not available
      interface_list=$1
      [ -z "$interface_list" ] && return 0
      for iface in $interface_list; do
	      if [ -z "`LC_ALL=C ip link show $iface | grep UP`" ]; then
		      return 1
	     fi
      done
      return 0
}



if [ -r /etc/snort/snort.debian.conf ] ; then
    . /etc/snort/snort.debian.conf
    # Set the variables in debconf using the configuration values 
    # (if defined)
    [ -n "$DEBIAN_SNORT_STARTUP" ] && { db_set snort/startup "$DEBIAN_SNORT_STARTUP"; db_fset snort/startup seen true ; }
    [ -n "$DEBIAN_SNORT_HOME_NET" ] && { db_set snort/address_range "$DEBIAN_SNORT_HOME_NET"; db_fset snort/address_range seen true ; }
    if [ ! -z "$DEBIAN_SNORT_OPTIONS" ] ; then
        # Remove the -p option wich is added in postinst due to the 'DISABLE_PROMISCUOUS' debconf option
        DEBIAN_SNORT_OPTIONS=`echo "$DEBIAN_SNORT_OPTIONS" | sed -e 's/ -p$//'`

        db_set snort/options "$DEBIAN_SNORT_OPTIONS" 
        db_fset snort/options seen true 
    fi
    [ -n "$DEBIAN_SNORT_SEND_STATS" ] && { db_set snort/send_stats "$DEBIAN_SNORT_SEND_STATS"; db_fset snort/send_stats seen true ; }
    [ -n "$DEBIAN_SNORT_STATS_RCPT" ] && { db_set snort/stats_rcpt "$DEBIAN_SNORT_STATS_RCPT" ; db_fset snort/stats_rcpt  seen true ; }
    [ -n "$DEBIAN_SNORT_STATS_THRESHOLD" ] && { db_set snort/stats_treshold "$DEBIAN_SNORT_STATS_THRESHOLD"; db_fset snort/stats_treshold seen true ; }
fi

INTERFACES=""
# Interface default in case the configuration file does not exist
# The default is to select all the interfaces which are UP in the system
if [ -z "$DEBIAN_SNORT_INTERFACE" ] ; then
    INTERFACES=$(list_interfaces)
    echo "Snort configuration: interface default not set, using '$INTERFACES'"
# Set eth0 as default if no interfaces are found, this raise the
# priority of the question as the interface is actually not found
    if [ -z "$INTERFACES" ] ; then
        INTERFACES=eth0 
        echo "Snort configuration: WARN: No network interface found, using $INTERFACES as default"
    fi
else 
    INTERFACES="$DEBIAN_SNORT_INTERFACE"
    echo "Snort configuration: interface default set, using $INTERFACES"
fi
[ -n "$INTERFACES" ] && { db_set snort/interface "$INTERFACES"; db_fset snort/interface seen true ; }

db_input low snort/startup || true
db_go

# /etc/ppp/ip-up.d/snort is called with interface and IP number
db_get snort/startup
if [ "x$RET" = "xdialup" ]; then
  db_set snort/interface ""
  db_set snort/address_range ""
  db_set snort/disable_promiscuous true
else

  db_beginblock

  # Ask for a valid set of interfaces
  ok=''
  count=0
  while [ ! "$ok" ] && [ "$count" -lt 2 ]; do
  # Depending on whether the default interface is up or down we set the
  # question priority
        priority='medium'
	if ! check_interfaces "$INTERFACES"
	then
            echo "Snort configuration: WARN: One of the interfaces is not UP in the system, raising question priority"
	    priority='high'
	    db_fset snort/interface seen false 
	fi
  # Raise the priority if there are multiple interfaces which are 
  # active in the system
	if [ $(count_interfaces "$INTERFACES") -gt 1 ]  
	then
	    priority='high'
	fi
	set +e
	db_input $priority snort/interface
        if [ $? -eq 30 ]; then
	# User is not being shown the question, break out
	     break
	fi
	set -e
	db_go || true
   # Check the interfaces
	db_get snort/interface
	INTERFACES=$RET
	if ! check_interfaces "$INTERFACES" ; then
          echo "Snort configuration: WARNING: The interfaces configured are not valid"
	  db_fset snort/invalid_interface seen false 
	  db_input critical snort/invalid_interface
	else
	  ok='yes'
        fi
	# Increment the count, we only go through this two times
	count=$(($count+1))
  done

  db_input high snort/address_range || true
  db_input low snort/disable_promiscuous || true
  db_endblock
  db_go
fi

db_beginblock
db_input low snort/options || true
db_endblock
db_go

db_beginblock
db_input low snort/send_stats || true
db_go

db_get snort/send_stats
if [ "x$RET" = "xtrue" ]; then
# TODO: This values should not be empty (even
# if we default to 'root' and '1' in the scripts)
# so the config script should check wether the 
# values here are legitimate.
	db_beginblock
	db_input medium snort/stats_rcpt || true
	db_input low snort/stats_treshold || true
	db_endblock
	db_go
fi

DEFAULT=/etc/default/snort
PARAMETERS=/etc/snort/snort.common.parameters
if [ -e "$DEFAULT" ] && [ -e "$PARAMETERS" ] ; then
	db_beginblock
	db_input high snort/config_parameters || true
	db_endblock
	db_go
fi

db_get snort/startup
if [ "x$RET" = "xmanual" ]; then
	db_beginblock
	db_input medium snort/please_restart_manually || true
	db_endblock
	db_go
fi

db_stop