#! /bin/sh
#
# network-functions: Network functions script for openmamba
#
# Copyright (c) 2003-2005 by Silvan Calarco <silvan.calarco@mambasoft.it>
# Copyright (c) 2003-2005,2011 by Davide Madrisan <davide.madrisan@gmail.com>

. /etc/sysconfig/rc

# ip_check_args()
#
# parameters:
#    $1 : ip/bitmask (like 192.168.0.1/24)  -or-
#    $1 $2 : ip netmask (like 192.168.0.1 255.255.255.0)
# description:
#    This function checks if its first / first two arguments are
#    a valid ipv4 address.
#    If it is a valid one, returns '1' and set the variables
#       $ip        (ip address)
#       $mask_bit  (number of active bits in the maks)
#       $mask      (mask)
#    otherwise returns '0'
ip_check_args ()
{
   local i

   # checks if the first argument is a valid one, that is something
   # like "192.168.0.1" or "192.168.0.1/24"
   if ! echo $1 | grep -Eq "^([0-9]+\.){3}[0-9]+(/[0-9]+){0,1}$"; then
      return 0
   fi
   ip=`echo $1 | cut -f1 -d/`
   for i in `seq 1 4`; do  # check for range in [0..255]
      local byte=`echo $ip | cut -f$i -d.`
      [ $byte -le 255 ] || return 0
   done
   # gets the mask from $1, if $1 is like '192.168.0.1/24',
   # otherwise 'mask_bit' is set to ""
   mask_bits=`echo $1 | cut -f2 -s -d/`
   if [ $mask_bits ]; then  # 'mask_bit' is not ""
      [ $mask_bits -le 32 ] || return 0  # illegal 'mask_bit'
      # set 'mask'. i.e. mask_bits = 24 --> mask = 255.255.255.0
      local mb=$mask_bits
      for i in `seq 1 4`; do
         if [ $mb -ge 8 ]; then
            mask=$mask"255"
            mb=$(($mb - 8))
         else
            mask=$mask$(( 256 - (2 << (7-$mb)) ))
            [ $mb -gt 0 ] && mb=0
         fi
         [ $i -lt 4 ] && mask=$mask"."
      done
   else  # $2 should be a network mask (like 255.255.255.0)
      if ! echo $2 | grep -Eq "^([0-9]+\.){3}[0-9]+$"; then
         return 0
      fi
      mask=$2
      local prev_byte=255
      local prev_bit=1
      mask_bits=0
      for i in `seq 1 4`; do
         local byte=`echo $mask | cut -f$i -d.`
         [ $byte -gt 255 ] && return 0
         # if the previous was < 255, the current one must be 0
         [ $prev_byte -lt 255 -a $byte -ne 0 ] && return 0
         # internal loop to set 'mask_bits'
         for j in `seq 7 0`; do
            local bit_value=$(( ($byte >> j) & 1 ))
            # if the previous bit was '0', the current can't be '1'
            [ $prev_bit -eq 0 -a $bit_value -eq 1 ] && return 0
            [ $bit_value -eq 1 ] && mask_bits=$(( $mask_bits + 1 ))
            prev_bit=$bit_value
         done
         prev_byte=$byte
      done
   fi
   return 1
}

# calculate_ip_parameters()
#
# parameters:
#    $1 : ip
#    $2 : netmask
# description:
#    This function set the variables
#        $network    (network address)
#        $broadcast  (broadcast address)
#        $wildcard   (wildcard mask)
#    calculated using as input the ip/network address $1/$2.
#    If $1/$2 is a valid ipv4 address, returns '0', otherwise
#    returns '1'
calculate_ip_parameters ()
{
   local i
   unset network broadcast wildcard

   ip_check_args $1 $2
   [ $? -eq 0 ] && return 1

   for i in 1 2 3 4; do
      ip_byte=`echo $ip | cut -f$i -d.`
      mask_byte=`echo $mask | cut -f$i -d.`
      ip_and_mask=$(( $ip_byte & $mask_byte ))
      mask_cplm=$(( 255 - $mask_byte ))
      wildcard=$wildcard$mask_cplm
      network=$network$ip_and_mask
      broadcast=$broadcast$((ip_and_mask + mask_cplm))
      if [ $i -lt 4 ]; then
         network=$network"."
         broadcast=$broadcast"."
         wildcard=$wildcard"."
      fi
   done
   return 0
}

# get_interface_parameters()
#
# parameters:
#    $1 : interface name (i.e. eth0)
# description:
#    If no error occurs, this function return '0' and set the variables
#        $int_ip
#        $int_netmask
#        $int_network
#        $int_broadcast
#        $int_static_ip   (0: static IP; 1: dynamic IP (DHCP))
#    to the system values found for interface $1, otherwise returns '1'
get_interface_parameters ()
{
   local int_name="$1"

   [ x"$int_name" != x ] || return 1

   int_ip=`/sbin/ifconfig $int_name 2>/dev/null | \
      sed -n '/inet addr/{s,.*inet addr:\([^ \t]*\).*,\1,;p}'`
   int_broadcast=`/sbin/ifconfig $int_name 2>/dev/null | \
      sed -n '/inet addr:.*Bcast:/{s,.*Bcast:\([^ \t]*\).*,\1,;p}'`
   int_netmask=`/sbin/ifconfig $int_name 2>/dev/null | \
      sed -n '/inet addr:.*Mask:/{s,.*Mask:\([^ \t]*\).*,\1,;p}'`

   # note: loopback interface has null 'int_broadcast' value
   [ -z "$int_ip" -o -z "$int_netmask" ] && return 1

   int_static_ip=1
   # this check was written to avoid backward compatibility issues
   if [ -r $network_devices/ifconfig.$int_name ]; then
      if grep -Eq "^BOOTPROTO=dhcp" $network_devices/ifconfig.$int_name; then
         int_static_ip=0
      fi
   fi

   calculate_ip_parameters "$int_ip" "$int_netmask"
   int_network=$network

   return 0
}