/* 
 * $Id: OctetConverter.java 5067 2005-03-24 06:10:10Z dfs $
 *
 * Copyright 2004-2005 Daniel F. Savarese
 * Contact Information: http://www.savarese.org/contact.html
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.savarese.org/software/ApacheLicense-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.azib.ipscan.util;

/**
 * OctetConverter is a utility singleton class for converting IP
 * octets to and from other representations.
 *
 * @author <a href="http://www.savarese.org/">Daniel F. Savarese</a>
 */
public final class OctetConverter {
  private OctetConverter() {}

  /**
   * Converts a set of IPv4 octets to a 32-bit word.
   *
   * @param octets A byte array containing the IPv4 octets.
   * @param offset The offset into the array where the octets start.
   * @return The 32-bit word representation of the IPv4 address.
   */
  public static int octetsToInt(byte[] octets, int offset) {
    return (((octets[offset] & 0xff) << 24) |
            ((octets[offset + 1] & 0xff) << 16) |
            ((octets[offset + 2] & 0xff) << 8) |
            (octets[offset + 3] & 0xff));
  }

  /**
   * Same as <code>octetsToInt(octets, 0);</code>
   */
  public static int octetsToInt(byte[] octets) {
    return octetsToInt(octets, 0);
  }

  /**
   * Converts a set of octets to a 64-bit word.
   *
   * @param octets A byte array containing the octets.
   * @param offset The offset into the array where the octets start.
   * @return The 64-bit word representation of the octets.
   */
  public static long octetsToLong(byte[] octets, int offset) {
    return (((octets[offset] & 0xffffL) << 56) |
            ((octets[offset + 1] & 0xffL) << 48) |
            ((octets[offset + 2] & 0xffL) << 40) |
            ((octets[offset + 3] & 0xffL) << 32) |
            ((octets[offset + 4] & 0xffL) << 24) |
            ((octets[offset + 5] & 0xffL) << 16) |
            ((octets[offset + 6] & 0xffL) << 8) |
            (octets[offset + 7] & 0xffL));
  }

  /**
   * Same as <code>octetsToLong(octets, 0);</code>
   */
  public static long octetsToLong(byte[] octets) {
    return octetsToLong(octets, 0);
  }

  /**
   * Converts a set of IPv4 octets to a string representation.
   *
   * @param buffer The StringBuffer to which to append the string.
   * @param octets A byte array containing the IPv4 octets.
   * @param offset The offset into the array where the octets start.
   */
  public static void octetsToString(StringBuffer buffer, byte[] octets, int offset) {
    buffer.append(octets[offset++] & 0xff);
    buffer.append(".");
    buffer.append(octets[offset++] & 0xff);
    buffer.append(".");
    buffer.append(octets[offset++] & 0xff);
    buffer.append(".");
    buffer.append(octets[offset++] & 0xff);
  }

  /**
   * Same as <code>octetsToString(buffer, octets, 0);</code>
   */
  public static void octetsToString(StringBuffer buffer, byte[] octets) {
    octetsToString(buffer, octets, 0);
  }

  /**
   * Converts a 32-bit word representation of an IPv4 address to a
   * string representation.
   *
   * @param buffer The StringBuffer to which to append the string.
   * @param address The 32-bit word representation of the address.
   */
  public static void intToString(StringBuffer buffer, int address) {
    buffer.append(0xff & (address >>> 24));
    buffer.append(".");
    buffer.append(0xff & (address >>> 16));
    buffer.append(".");
    buffer.append(0xff & (address >>> 8));
    buffer.append(".");
    buffer.append(0xff & address);
  }

  /**
   * Converts a 32-bit word representation of an IPv4 address to a
   * byte array of octets.
   *
   * @param address The 32-bit word representation of the IPv4 address.
   * @param octets The byte array in which to store the IPv4 octets.
   * @param offset The offset into the array where the octets start.
   */
  public static void intToOctets(int address, byte[] octets, int offset) {
    octets[offset]     = (byte)(0xff & (address >>> 24));
    octets[offset + 1] = (byte)(0xff & (address >>> 16));
    octets[offset + 2] = (byte)(0xff & (address >>> 8));
    octets[offset + 3] = (byte)(0xff & address);
  }

  /**
   * Same as <code>intToOctets(address, octets, 0);</code>
   */
  public static void intToOctets(int address, byte[] octets) {
    intToOctets(address, octets, 0);
  }

  /**
   * Converts a 64-bit word to a byte array of octets.
   *
   * @param address The 64-bit word.
   * @param octets The byte array in which to store octets.
   * @param offset The offset into the array where the octets start.
   */
  public static void longToOctets(long address, byte[] octets, int offset) {
    octets[offset]     = (byte)(0xffL & (address >>> 56));
    octets[offset + 1] = (byte)(0xffL & (address >>> 48));
    octets[offset + 2] = (byte)(0xffL & (address >>> 40));
    octets[offset + 3] = (byte)(0xffL & (address >>> 32));
    octets[offset + 4] = (byte)(0xffL & (address >>> 24));
    octets[offset + 5] = (byte)(0xffL & (address >>> 16));
    octets[offset + 6] = (byte)(0xffL & (address >>> 8));
    octets[offset + 7] = (byte)(0xffL & address);
  }


  /**
   * Same as <code>longToOctets(address, octets, 0);</code>
   */
  public static void longToOctets(long address, byte[] octets) {
    longToOctets(address, octets, 0);
  }
}
