classip

#!/usr/bin/env bash
#
# classip :: ipv4 class information
# requires: bash 3.2+

trap 'echo -e "\nSIGINT Received... exiting"; exit 130' SIGINT

err() {
  # send errors to standard error
  echo "[${0##*/}] error: $*" >&2
}

show_help() {
  # help option text
  echo "Usage: ${0##*/} [OPTION]... [IP ADDRESS]..."
  echo "Options:"
  echo "  -h, --help    Show this help menu"
  echo "  -c            Show all IP class ranges"
  echo "  -r            Show all private IP ranges"
  echo "  -s            Show all special IP ranges"
}

_parse_options() {
  # parse arguments and assign variables, arrays

  # check for long "--help"
  if [[ "$1" == "--help" ]]; then
    show_help
    showed_help="1"
    return 0
  fi

  # showed_help, class, private, special - must be declared in main
  local opt=""
  while getopts ":hcrs" opt; do
    case "$opt" in
      h)
        show_help
        showed_help="1"
        return 0
        ;;
      c) class="c" ;;
      r) private="r" ;;
      s) special="s" ;;
      \?)
        err "Invalid option: -$OPTARG"
        show_help
        return 1
        ;;
    esac
  done
}

print_class_info() {
  # message echo'd to the terminal to see classes and ip ranges
  echo "           All IP Ranges"
  echo "------------------------------------"
  echo " Class   Range"
  echo "------------------------------------"
  echo " A       0.0.0.0 - 127.255.255.255"
  echo " B       128.0.0.0 - 191.255.255.255"
  echo " C       192.0.0.0 - 223.168.255.255"
  echo " D       224.0.0.0 - 239.255.255.255"
  echo " E       240.0.0.0 - 255.255.255.255"
  echo ""
}

print_private_info() {
  # message echo'd to the terminal to see private ip ranges
  echo "          Private IP Ranges"
  echo "--------------------------------------"
  echo " Class   Range"
  echo "--------------------------------------"
  echo " A       10.0.0.0 - 10.255.255.255"
  echo " B       172.16.0.0 - 172.31.255.255"
  echo " C       192.168.0.0 - 192.168.255.255"
  echo " D       224.0.0.0 - 239.255.255.255"
  echo " E       240.0.0.0 - 255.255.255.255"
  echo ""
}

print_special_info() {
  # message echo'd to the terminal to see special ip information
  echo "            Special IPv4 Addresses"
  echo "---------------------------------------------------"
  echo " Type                 Range"
  echo "---------------------------------------------------"
  echo " Loopback             127.0.0.1 - 127.255.255.255"
  echo " Link-local / APIPA   169.254.0.0 - 169.254.255.255"
  echo " Multicast (Class D)  224.0.0.0 - 239.255.255.255"
  echo " Reserved (Class E)   240.0.0.0 - 255.255.255.255"
  echo ""
}

option_printer() {
  # print output based on arguments/options
  #
  # ARG $1: options string
  # RET: none, runs print functions based on $1

  [[ "$1" =~ c|r|s ]] && echo ""
  [[ "$1" =~ c ]] && print_class_info
  [[ "$1" =~ r ]] && print_private_info
  [[ "$1" =~ s ]] && print_special_info

  # return passed if no options were requested
  return 0
}

validate_ip_address() {
  # assess if a given ip address is a valid ipv4 address
  #
  # ARG $1: ip address
  # RET: 1 if failed

  if ! [[ "$1" =~ ^([0-9]{1,3}\.){3}[0-9]{1,3}$ ]]; then
    err "\"${1}\" is not a valid IP address!"
    return 1
  fi

  local -a ip_array=()

  # convert ip address to an array
  IFS='.' read -r -a ip_array <<< "$1"

  local octet_value=""
  for octet_value in "${ip_array[@]}"; do
    if [[ "$octet_value" != "0" && "$octet_value" =~ ^0 ]]; then
      err "\"${1}\" is not a valid IP address!"
      return 1
    fi

    if (( octet_value < 0 || octet_value > 255 )); then
      err "\"${1}\" is not a valid IP address!"
      return 1
    fi
  done

  # return - input validation passed
  return 0
}

get_ip_class() {
  # determine the ip class (A, B, C, D, E)
  #
  # ARG $1: ip address
  # RET: ip class

  local ip_first_octet="${1%%\.*}"

  if (( ip_first_octet >= 0 && ip_first_octet <= 127 )); then
    echo -n "A"
  elif (( ip_first_octet >= 128 && ip_first_octet <= 191 )); then
    echo -n "B"
  elif (( ip_first_octet >= 192 && ip_first_octet <= 223 )); then
    echo -n "C"
  elif (( ip_first_octet >= 224 && ip_first_octet <= 239 )); then
    echo -n "D"
  elif (( ip_first_octet >= 240 && ip_first_octet <= 255 )); then
    echo -n "E"
  fi
}

get_ip_pripub() {
  # determine if ip address is private or public
  #
  # ARG $1: ip address
  # RET: private or public

  local -a ip_array=()
  IFS='.' read -r -a ip_array <<< "$1"

  if (( ip_array[0] == 10 )); then
    echo -n "private"
  elif (( ip_array[0] == 169 && ip_array[1] == 254 )); then
    echo -n "private"
  elif (( ip_array[0] == 172 && ip_array[1] >= 16 && ip_array[1] <= 31 )); then
    echo -n "private"
  elif (( ip_array[0] == 192 && ip_array[1] == 168 )); then
    echo -n "private"
  elif (( ip_array[0] >= 224 && ip_array[0] <= 255 )); then
    echo -n "private"
  else
    echo -n "public"
  fi
}

get_ip_special() {
  # determine if an ip address is a special address
  # special addresses: loopback, link-local/apipa, multicast, reserved
  #
  # ARG $1: ip address
  # RET: special ip type, or nothing

  local -a ip_array=()
  IFS='.' read -r -a ip_array <<< "$1"

  if (( ip_array[0] == 127 )); then
    echo -n "loopback"
  elif (( ip_array[0] == 169 && ip_array[1] == 254 )); then
    echo -n "link-local"
  elif (( ip_array[0] >= 224 && ip_array[0] <= 239 )); then
    echo -n "multicast"
  elif (( ip_array[0] >= 240 && ip_array[0] <= 255 )); then
    echo -n "reserved"
  fi
}

main() {
  set -eu

  # define variables that can be assigned in _parse_options
  local showed_help="" class="" private="" special=""
  if [[ $# -gt 0 ]]; then
    _parse_options "$@"
    [[ -n "$showed_help" ]] && exit 0
  else
    err "One argument required: <option> and/or <ip address>"
    echo "---"
    show_help
    exit 1
  fi
  shift $((OPTIND - 1)) # shift $@ past optional flags

  option_printer "${class}${private}${special}"

  local ip_address="" ip_class="" ip_pripub="" ip_special="" write_out=""
  fail_rc="" # if any ip address was invalid; return non-zero rc
  # iterate through ip addresses and gather and print information
  for ip_address in "$@"; do
    if ! validate_ip_address "$ip_address"; then
      fail_rc="1"
      continue
    fi

    ip_class=$(get_ip_class "$ip_address")
    ip_pripub=$(get_ip_pripub "$ip_address")
    ip_special=$(get_ip_special "$ip_address")
    write_out="$ip_address : $ip_class $ip_pripub $ip_special"
    echo "${write_out%"${write_out##*[![:space:]]}"}" # trim trailing whitespace
  done

  [[ -z "$fail_rc" ]] && exit 0
  [[ -n "$fail_rc" ]] && exit 1
}

main "$@"