InetUtils.scala

import java.net.InetAddress
import java.nio.ByteBuffer

object InetUtils {
  private[this] val Radix = 16

  // Fast Hex converters

  private[this] val HexChars: Array[Char] = "0123456789ABCDEF".toCharArray

  // to lowercase hex chars
  @inline def byteToHex(b: Byte): String =
    byteToHexU(new Array[Char](2), 0, b).mkString

  // fill buffer starting with startIndex with two Hex chars
  @inline def byteToHexL(buf: Array[Char], startIndex: Int, b: Byte): Array[Char] = {
    buf(startIndex) = Character.forDigit((b >> 4) & 0x0F, Radix)
    buf(startIndex + 1) = Character.forDigit(b & 0x0F, Radix)
    buf
  }

  // fill buffer starting with startIndex with two Hex chars in UpperCase
  @inline def byteToHexU(buf: Array[Char], startIndex: Int, b: Byte): Array[Char] = {
    buf(startIndex) = HexChars((b >> 4) & 0x0F)
    buf(startIndex + 1) = HexChars(b & 0x0F)
    buf
  }

  @inline def hexToByte(s: String): Byte = (
    (Character.digit(s.charAt(0), Radix) << 4) +
      Character.digit(s.charAt(1), Radix)
    ).toByte

  // IP-address ops

  @inline def ipToInt(ip: String): Int =
    ByteBuffer.wrap(InetAddress.getByName(ip).getAddress).getInt

  @inline def intToIp(ip: Int): String = Seq(
    ((ip >> 24) & 0xFF).toShort,
    ((ip >> 16) & 0xFF).toShort,
    ((ip >> 8) & 0xFF).toShort,
    ((ip >> 0) & 0xFF).toShort
  ).mkString(".")

  // MAC-address ops - MAC TO Long

  @inline def macToLong(mac: String): Long = {
    val bytes = mac.split(":").map(hexToByte)
    val b8 = new Array[Byte](8)
    bytes.copyToArray(b8, Math.max(0, 8 - bytes.length), 8)
    ByteBuffer.wrap(b8).getLong
  }
  
  // MAC-address ops - Long To MAC

  @inline def longToMac(mac: Long): String = longToMac48(mac)

  // Fastest LongToMac-48 version
  @inline def longToMac48(address: Long): String = {
    val buf = new Array[Char](17)
    byteToHexU(buf, 0, ((address >> 40) & 0xFF).toByte)
    buf(2) = ':'
    byteToHexU(buf, 3, ((address >> 32) & 0xFF).toByte)
    buf(5) = ':'
    byteToHexU(buf, 6, ((address >> 24) & 0xFF).toByte)
    buf(8) = ':'
    byteToHexU(buf, 9, ((address >> 16) & 0xFF).toByte)
    buf(11) = ':'
    byteToHexU(buf, 12, ((address >> 8) & 0xFF).toByte)
    buf(14) = ':'
    byteToHexU(buf, 15, ((address >> 0) & 0xFF).toByte)
    new String(buf)
  }

  // Fastest LongToMac-64 version
  @inline def longToMac64(address: Long): String = {
    val buf = new Array[Char](23)
    byteToHexU(buf, 0, ((address >> 56) & 0xFF).toByte)
    buf(2) = ':'
    byteToHexU(buf, 3, ((address >> 48) & 0xFF).toByte)
    buf(5) = ':'
    byteToHexU(buf, 6, ((address >> 40) & 0xFF).toByte)
    buf(8) = ':'
    byteToHexU(buf, 9, ((address >> 32) & 0xFF).toByte)
    buf(11) = ':'
    byteToHexU(buf, 12, ((address >> 24) & 0xFF).toByte)
    buf(14) = ':'
    byteToHexU(buf, 15, ((address >> 16) & 0xFF).toByte)
    buf(17) = ':'
    byteToHexU(buf, 18, ((address >> 8) & 0xFF).toByte)
    buf(20) = ':'
    byteToHexU(buf, 21, ((address >> 0) & 0xFF).toByte)
    new String(buf)
  }
}