/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project licenses this file to you 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.apache.org/licenses/LICENSE-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 org.jboss.netty.handler.ipfilter;
  
  import java.net.Inet4Address;
  import java.net.Inet6Address;
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  import java.util.StringTokenizer;
  
  /**
   */
  public abstract class CIDR implements Comparable<CIDR> {
      /** The base address of the CIDR notation */
      protected InetAddress baseAddress;
  
      /** The mask used in the CIDR notation */
      protected int cidrMask;
  
      /**
       * Create CIDR using the CIDR Notation
       *
       * @return the generated CIDR
       */
      public static CIDR newCIDR(InetAddress baseAddress, int cidrMask) throws UnknownHostException {
          if (cidrMask < 0) {
              throw new UnknownHostException("Invalid mask length used: " + cidrMask);
          }
          if (baseAddress instanceof Inet4Address) {
              if (cidrMask > 32) {
                  throw new UnknownHostException("Invalid mask length used: " + cidrMask);
              }
              return new CIDR4((Inet4Address) baseAddress, cidrMask);
          }
          // IPv6.
          if (cidrMask > 128) {
              throw new UnknownHostException("Invalid mask length used: " + cidrMask);
          }
          return new CIDR6((Inet6Address) baseAddress, cidrMask);
      }
  
      /**
       * Create CIDR using the normal Notation
       *
       * @return the generated CIDR
       */
      public static CIDR newCIDR(InetAddress baseAddress, String scidrMask) throws UnknownHostException {
          int cidrMask = getNetMask(scidrMask);
          if (cidrMask < 0) {
              throw new UnknownHostException("Invalid mask length used: " + cidrMask);
          }
          if (baseAddress instanceof Inet4Address) {
              if (cidrMask > 32) {
                  throw new UnknownHostException("Invalid mask length used: " + cidrMask);
              }
              return new CIDR4((Inet4Address) baseAddress, cidrMask);
          }
          cidrMask += 96;
          // IPv6.
          if (cidrMask > 128) {
              throw new UnknownHostException("Invalid mask length used: " + cidrMask);
          }
          return new CIDR6((Inet6Address) baseAddress, cidrMask);
      }
  
      /**
       * Create CIDR using the CIDR or normal Notation<BR>
       * i.e.:
       * CIDR  subnet = newCIDR ("10.10.10.0/24"); or
       * CIDR  subnet = newCIDR ("1fff:0:0a88:85a3:0:0:ac1f:8001/24"); or
       * CIDR  subnet = newCIDR ("10.10.10.0/255.255.255.0");
       *
       * @return the generated CIDR
       */
      public static CIDR newCIDR(String cidr) throws UnknownHostException {
          int p = cidr.indexOf('/');
          if (p < 0) {
              throw new UnknownHostException("Invalid CIDR notation used: " + cidr);
          }
          String addrString = cidr.substring(0, p);
          String maskString = cidr.substring(p + 1);
          InetAddress addr = addressStringToInet(addrString);
          int mask;
          if (maskString.indexOf('.') < 0) {
              mask = parseInt(maskString, -1);
          } else {
             mask = getNetMask(maskString);
             if (addr instanceof Inet6Address) {
                 mask += 96;
             }
         }
         if (mask < 0) {
             throw new UnknownHostException("Invalid mask length used: " + maskString);
         }
         return newCIDR(addr, mask);
     }
 
     /** @return the baseAddress of the CIDR block. */
     public InetAddress getBaseAddress() {
         return baseAddress;
     }
 
     /** @return the Mask length. */
     public int getMask() {
         return cidrMask;
     }
 
     /** @return the textual CIDR notation. */
     @Override
     public String toString() {
         return baseAddress.getHostAddress() + '/' + cidrMask;
     }
 
     /** @return the end address of this block. */
     public abstract InetAddress getEndAddress();
 
     /**
      * Compares the given InetAddress against the CIDR and returns true if
      * the ip is in the subnet-ip-range and false if not.
      *
      * @return returns true if the given IP address is inside the currently
      *         set network.
      */
     public abstract boolean contains(InetAddress inetAddress);
 
     @Override
     public boolean equals(Object o) {
         if (!(o instanceof CIDR)) {
             return false;
         }
         return compareTo((CIDR) o) == 0;
     }
 
     @Override
     public int hashCode() {
         return baseAddress.hashCode();
     }
 
     /**
      * Convert an IPv4 or IPv6 textual representation into an
      * InetAddress.
      *
      * @return the created InetAddress
      */
     private static InetAddress addressStringToInet(String addr) throws UnknownHostException {
         return InetAddress.getByName(addr);
     }
 
     /**
      * Get the Subnet's Netmask in Decimal format.<BR>
      * i.e.: getNetMask("255.255.255.0") returns the integer CIDR mask
      *
      * @param netMask a network mask
      * @return the integer CIDR mask
      */
     private static int getNetMask(String netMask) {
         StringTokenizer nm = new StringTokenizer(netMask, ".");
         int i = 0;
         int[] netmask = new int[4];
         while (nm.hasMoreTokens()) {
             netmask[i] = Integer.parseInt(nm.nextToken());
             i++;
         }
         int mask1 = 0;
         for (i = 0; i < 4; i++) {
             mask1 += Integer.bitCount(netmask[i]);
         }
         return mask1;
     }
 
     /**
      * @param intstr a string containing an integer.
      * @param def    the default if the string does not contain a valid
      *               integer.
      * @return the inetAddress from the integer
      */
     private static int parseInt(String intstr, int def) {
         Integer res;
         if (intstr == null) {
             return def;
         }
         try {
             res = Integer.decode(intstr);
         } catch (Exception e) {
             res = def;
         }
         return res.intValue();
     }
 
     /**
      * Compute a byte representation of IpV4 from a IpV6
      *
      * @return the byte representation
      * @throws IllegalArgumentException if the IpV6 cannot be mapped to IpV4
      */
     public static byte[] getIpV4FromIpV6(Inet6Address address) {
         byte[] baddr = address.getAddress();
         for (int i = 0; i < 9; i++) {
             if (baddr[i] != 0) {
                 throw new IllegalArgumentException("This IPv6 address cannot be used in IPv4 context");
             }
         }
         if (baddr[10] != 0 && baddr[10] != 0xFF || baddr[11] != 0 && baddr[11] != 0xFF) {
             throw new IllegalArgumentException("This IPv6 address cannot be used in IPv4 context");
         }
         return new byte[]
                 {baddr[12], baddr[13], baddr[14], baddr[15]};
     }
 
     /**
      * Compute a byte representation of IpV6 from a IpV4
      *
      * @return the byte representation
      * @throws IllegalArgumentException if the IpV6 cannot be mapped to IpV4
      */
     public static byte[] getIpV6FromIpV4(Inet4Address address) {
         byte[] baddr = address.getAddress();
         return new byte[]
                 {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, baddr[0], baddr[1], baddr[2], baddr[3]};
     }
 }