IPMask.java

/*
 *    This file is part of ReadonlyREST.
 *
 *    ReadonlyREST is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    ReadonlyREST is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with ReadonlyREST.  If not, see http://www.gnu.org/licenses/
 */

package org.elasticsearch.plugin.readonlyrest.acl.domain;

import java.net.Inet4Address;
import java.net.InetAddress;
import java.net.UnknownHostException;

/**
 * Represents an IP range based on an address/mask.
 *
 * @author Scott Plante, using code snippets by John Kugelman.
 */
public class IPMask {
  private Inet4Address i4addr;
  private byte maskCtr;

  private int addrInt;
  private int maskInt;

  public IPMask(Inet4Address i4addr, byte mask) {
    this.i4addr = i4addr;
    this.maskCtr = mask;

    this.addrInt = addrToInt(i4addr);
    this.maskInt = ~((1 << (32 - maskCtr)) - 1);
  }

  /**
   * IPMask factory method.
   *
   * @param addrSlashMask IP/Mask String in format "nnn.nnn.nnn.nnn/mask". If
   *                      the "/mask" is omitted, "/32" (just the single address) is assumed.
   * @return a new IPMask
   * @throws UnknownHostException if address part cannot be parsed by
   *                              InetAddress
   */
  public static IPMask getIPMask(String addrSlashMask)
      throws UnknownHostException {
    int pos = addrSlashMask.indexOf('/');
    String addr;
    byte maskCtr;
    if (pos == -1) {
      addr = addrSlashMask;
      maskCtr = 32;
    }
    else {
      addr = addrSlashMask.substring(0, pos);
      maskCtr = Byte.parseByte(addrSlashMask.substring(pos + 1));
    }
    return new IPMask((Inet4Address) InetAddress.getByName(addr), maskCtr);
  }

  /**
   * Converts IPv4 address to integer representation.
   */
  private static int addrToInt(Inet4Address i4addr) {
    byte[] ba = i4addr.getAddress();
    return (ba[0] << 24)
        | ((ba[1] & 0xFF) << 16)
        | ((ba[2] & 0xFF) << 8)
        | (ba[3] & 0xFF);
  }

  /**
   * Test given IPv4 address against this IPMask object.
   *
   * @param testAddr address to check.
   * @return true if address is in the IP Mask range, false if not.
   */
  public boolean matches(Inet4Address testAddr) {
    int testAddrInt = addrToInt(testAddr);
    // Always allow 0.0.0.0/0 as a wild card
    if (maskInt == -1 && addrInt == 0) {
      return true;
    }
    return (addrInt & maskInt) == (testAddrInt & maskInt);
  }

  /**
   * Convenience method that converts String host to IPv4 address.
   *
   * @param addr IP address to match in nnn.nnn.nnn.nnn format or hostname.
   * @return true if address is in the IP Mask range, false if not.
   * @throws UnknownHostException if the string cannot be decoded.
   */
  public boolean matches(String addr)
      throws UnknownHostException {
    return matches((Inet4Address) InetAddress.getByName(addr));
  }

  @Override
  public String toString() {
    return "IPMask(" + i4addr.getHostAddress() + "/" + maskCtr + ")";
  }

  @Override
  public boolean equals(Object obj) {
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    final IPMask that = (IPMask) obj;
    return this.addrInt == that.addrInt && this.maskInt == that.maskInt;
  }

  @Override
  public int hashCode() {
    return this.maskInt + this.addrInt;
  }

}