How to convert IPv6 Addresses to and from BigInteger in Scala

Question

Looking to convert IPv6 Strings (such as 2001:0:4137:9e76:34b7:2e31:3f57:fd9a) to BigInteger and from BigInteger to IPv6 Strings.

Answer 1

import java.math.BigInteger
import java.net.InetAddress
import java.net.Inet6Address
def ipv6ToBigInteger(ipv6 : String) : BigInteger = {
    val ia = InetAddress.getByName(ipv6)
    val byteArr : Array[Byte] = ia.getAddress()
    var ipNumber = new BigInteger("0")
    if (ia.isInstanceOf[Inet6Address]) {
        ipNumber = new BigInteger(1, byteArr)
    }
    return ipNumber
}

def bigIntegerToIPv6(ipv6Num : BigInteger) : String = {
    val ipv6Str = InetAddress.getByAddress(ipv6Num.toByteArray).toString()
    return ipv6Str.replaceFirst("/", "")
}

val ipv6 = "2001:0:4137:9e76:34b7:2e31:3f57:fd9a"
val ipv6Num = ipv6ToBigInteger(ipv6) // ipv6Num: java.math.BigInteger = 42540488182159607633435240198452018586
val ipv6Str = bigIntegerToIPv6(ipv6Num) // ipv6Str: String = 2001:0:4137:9e76:34b7:2e31:3f57:fd9a
ipv6 == ipv6Str // res0: Boolean = true

UPDATE EDIT:

Per a suggested edit from an anonymous user:

"Comment: InetAddress.getByAddress requires a 16-byte array in order to parse an IPv6 address (4-byte array for IPv4). As it was, the code failed for any value that did not result in a 16-byte array when .toByteArray was called on it"

def bigIntToFixedSizeByteArray(n: BigInteger, size: Int = 16): Array[Byte] = {
    val a = n.toByteArray
    val leadingLength = math.max(size - a.length, 0)
    Array.ofDim[Byte](leadingLength) ++ a
}

def bigIntegerToIPv6(ipv6Num : BigInteger) : String = {
    val address = InetAddress.getByAddress(bigIntToFixedSizeByteArray(ipv6Num))  
    address.toString.replaceFirst("/", "")
}