common.sh

#!/bin/sh

>&2 echo -e "- using \e[31mwg${WGID}\e[0m on network \e[32m${IP_FIRST}/${MASK}\e[0m -"
>&2 echo 

dec2ip() {
  # itoa
  # returns the dotted-decimal ascii form of an IP arg passed in integer format
  echo -n $(($((${1}/16777216))%256)).
  echo -n $(($((${1}/65536))%256)).
  echo -n $(($((${1}/256))%256)).
  echo $((${1}%256))
}

ip2dec() {
  # atoi
  # Returns the integer representation of an IP arg, passed in ascii dotted-decimal notation (x.x.x.x)
  local a b c d ip=$1
  IFS=. read -r a b c d <<< "$ip"
  echo $((a * 256 ** 3 + b * 256 ** 2 + c * 256 + d))
}

# get IP count - 1 in mask
# 32 => 1,  31 => 2
# 30 => 4,  29 => 8
# 28 => 16, 27 => 32 ...
maskSize() { echo $((2 ** (32 - $1) )); }

# translatre IP
# $1 IP base but use global $IP_FIRST
# $2 offsettrIP
trIP() {
  DEC=$(ip2dec $IP_FIRST)
  DEC=$(($DEC+$2))
  echo $(dec2ip $DEC)
}

# translatre IP
# $1 IP base but use global $IP_FIRST
# $2 selected IP
getIPOffset() {
  FROM=$(ip2dec $IP_FIRST)
  TO=$(ip2dec $2)
  DIFF=$(($TO-$FROM))
  echo $DIFF
}