Netmask to bits & bits to netmask

networking.sh

#!/usr/bin/env bash
#shellcheck disable=SC2206,SC2207

ipv4_netmask() {
  local IFS='.' netmask=() rest_bits tmp_netmask=0
  local -r bits="${1:-0}"

  if [[ $bits -lt 0 || $bits -gt 32 ]]; then
    echo "Error: IPv4 netmask should be between 0 and 32" 1>&2
    return 1
  fi

  local -r complete=$(( bits / 8 ))
  rest_bits=$(( bits % 8 ))

  until [[ ${#netmask[@]} -eq $complete ]]; do
    netmask+=("255")
  done

  if [[ $rest -lt 8 ]]; then
    while [[ $rest_bits -gt 0 ]]; do
      tmp_netmask=$(( ( 2 ** ( 8 - rest_bits ) ) + tmp_netmask ))
      rest_bits=$(( rest_bits - 1 ))
    done
    netmask+=("$tmp_netmask")
  fi

  while [[ ${#netmask[@]} -lt 4 ]]; do
    netmask+=("0")
  done

  echo "${netmask[*]}"
}

ipv4_wildcard() {
  local IFS='.' netmask=() i
  local -r bits="${1:-0}"

  netmask=(${1:-0})

  if [[ ${#netmask[@]} -eq 1 ]]; then
    netmask=($(ipv4_netmask "${1:-0}"))
  fi

  for i in "${!netmask[@]}"; do
    if [[ ${netmask[$i]} -lt 0 || ${netmask[$i]} -gt 255 ]]; then
      echo "Network mask should not have any octet lower than 0 and greater than 255" 1>&2
      return 1
    fi
    netmask["$i"]=$(( 255 - netmask[i] ))
  done

  echo "${netmask[*]}"
}

ipv4_bits_to_mask() {
  local mask=0 bits="${1:-0}"

  if [[ $bits -lt 0 || $bits -gt 8 ]]; then
    echo "Invalid number of bits"
    return 1
  fi

  while [[ $bits -gt 0 ]]; do
    mask=$(( ( 2 ** ( 8 - bits ) ) + mask ))
    bits=$(( bits - 1 ))

    if [[ $mask -lt 0 ]]; then
      echo "Invalid mask?" 1>&2
      return 1
    fi
  done

  echo "$mask"
}

ipv4_mask_to_bits() {
  local bits=0 mask="${1:-0}"
  if [[ $mask -gt 255 || $mask -lt 0 ]]; then
    echo "Octet should be between 0 and 255" 1>&2
    return 1
  fi

  while [[ $mask -gt 0 ]]; do
    bits=$(( bits + 1 ))
    mask=$(( mask - ( 2 ** ( 8 - bits ) ) ))

    if [[ $mask -lt 0 ]]; then
      echo "Invalid mask" 1>&2
      return 1
    fi
  done

  echo "$bits"
}

ipv4_bits() {
  local IFS='.' bits=0 total_bits=0 netmask

  netmask=(${1:-0.0.0.0})

  if [[ ${#netmask[@]} -eq 1 && ${netmask[0]} -ge 0 && ${netmask[0]} -le 32 ]]; then
    echo "${1:-0}"
    return
  elif [[ ${#netmask[@]} -ne 4 ]]; then
    echo "Network mask should have 4 octetts" 1>&2
    return 1
  fi

  for i in "${!netmask[@]}"; do
    if [[ ${netmask[$i]} -lt 0 || ${netmask[$i]} -gt 255 ]]; then
      echo "Network mask should not have any octet lower than 0 and greater than 255" 1>&2
      return 1
    fi
    bits=0

    while [[ ${netmask[$i]} -gt 0 ]]; do
      bits=$(( bits + 1))
      netmask[$i]=$(( netmask[i] - ( 2 ** ( 8 - bits ) ) ))
      
      if [[ netmask[$i] -lt 0 ]]; then
        echo "Invalid mask" 1>&2
        return 1
      fi
    done
    total_bits=$(( total_bits + bits ))
  done

  echo "$total_bits"
}

validate_ip_cidr() {
  [[ $1 =~ ^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\/(3[0-2]|[0-2]?[0-9]{1})$ ]] ||
    [[ $1 =~ ^([0-9a-fA-F]{0,4}:){1,7}[0-9a-fA-F]{0,4}\/(12[0-8]|1[0-1][0-9]|[0-9]?[0-9]{1})$ ]]
}

validate_ip() {
  [[ "$1" =~ ^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$ ]] ||
    [[ $1 =~ ^([0-9a-fA-F]{0,4}:){1,7}[0-9a-fA-F]{0,4}$ ]]
}

ipGetMask() {
  local bits
  bits="$(echo "$1" | grep -E -o "(\/(3[0-2]|[0-2]?[0-9]{1})?)$" || echo "/-1")"
  bits="${bits:1}"

  if [[ $bits -ge 0 && $bits -le 32 ]]; then
    echo "$bits"
  fi
}

ipv4_netmask 24
ipv4_wildcard 24
ipv4_wildcard 255.128.0.0
ipv4_bits 255.255.128.0
ipv4_bits_to_mask 2
ipv4_mask_to_bits 192