Bash variables and types

Question

I'm making a script that validate an IP address. I do this:

read pool
checkIp()
{
    local  ip=$1
    local  stat=1

    if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        OIFS=$IFS
        IFS='.'
        ip=($ip)
        IFS=$OIFS
        [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 && ${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
        stat=$?

    fi
    return $stat
}

checkIp $pool
if [ $? -eq 0 ]
    then
        echo "valid"
    else
        echo "invalid"
fi

The problem is that now the requirement is to valid that from the 2nd octet the input can contain the wildcard "*" (i think is better to use CIDR notation but is not the case), and now i can't use -le because if there is not a number, it fails.

I'd tried some forms but all conversions fails.

Answer 1

With a little additional rewrite. (As you use Bash-specific regular expression, just populate the BASH_REMATCH array instead of manipulating a word splitting.)

checkIp()
{
  local ip="$1"

  if [[ "$ip" =~ ^([0-9]{1,3})\.([0-9]{1,3}|\*)\.([0-9]{1,3}|\*)\.([0-9]{1,3}|\*)$ ]]; then
    for ((i=1;i<=4;i++)); do
      [[ "${BASH_REMATCH[i]}" == '*' || "${BASH_REMATCH[i]}" -le 255 ]] || return 1
    done

    return 0
  fi

  return 1
}

Update according to owner's comment to disallow numbers after “*”:

checkIp()
{
  local ip="$1"
  local asterisk=''

  if [[ "$ip" =~ ^([0-9]{1,3})\.([0-9]{1,3}|\*)\.([0-9]{1,3}|\*)\.([0-9]{1,3}|\*)$ ]]; then
    for ((i=1;i<=4;i++)); do
      [[ "${BASH_REMATCH[i]}" == '*' || ( ! "$asterisk" && "${BASH_REMATCH[i]}" -le 255 ) ]] || return 1
      [[ "${BASH_REMATCH[i]}" == '*' ]] && asterisk='1'
    done

    return 0
  fi

  return 1
}

Answer 2

For the record, with zsh, you could write it:

[[ $ip = <0-255>.(<0-255>|"*").(<0-255>|"*").(<0-255>|"*") ]]

Note that it allows 000001.0000255.*.0, but not 0377.1.1.1 (even though 0377 as taken as an octal number is within range), because it only considers decimal numbers.