/*
    * Copyright 2002-2016 the original author or authors.
    *
    * 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.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.
   *
   * Retrieved on 8-March-2018 from https://raw.githubusercontent.com/spring-projects/spring-security/f221920a1990f458b26b185c8fbe5b3623dbd8c1/web/src/main/java/org/springframework/security/web/util/matcher/IpAddressMatcher.java
   */
  package com.atlassian.httpclient.apache.httpcomponents;
  
  import org.apache.commons.lang3.StringUtils;
  
  import javax.servlet.http.HttpServletRequest;
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  import java.util.Arrays;
  
  /**
   * Matches a request based on IP Address or subnet mask matching against the remote
   * address.
   * <p>
   * Both IPv6 and IPv4 addresses are supported, but a matcher which is configured with an
   * IPv4 address will never match a request which returns an IPv6 address, and vice-versa.
   *
   * @author Luke Taylor
   * @since 3.0.2
   */
  public final class IpAddressMatcher {
  
      private final int nMaskBits;
      private final InetAddress requiredAddress;
  
      /**
       * Takes a specific IP address or a range specified using the IP/Netmask (e.g.
       * 192.168.1.0/24 or 202.24.0.0/14).
       *
       * @param ipAddress the address or range of addresses from which the request must
       *                  come.
       */
      public IpAddressMatcher(String ipAddress) {
          if (ipAddress.indexOf('/') > 0) {
              String[] addressAndMask = StringUtils.split(ipAddress, "/");
              ipAddress = addressAndMask[0];
              nMaskBits = Integer.parseInt(addressAndMask[1]);
          } else {
              nMaskBits = -1;
          }
          requiredAddress = parseAddress(ipAddress);
      }
  
      public boolean matches(HttpServletRequest request) {
          return matches(request.getRemoteAddr());
      }
  
      public boolean matches(String address) {
          InetAddress remoteAddress = parseAddress(address);
  
          if (!requiredAddress.getClass().equals(remoteAddress.getClass())) {
              return false;
          }
  
          if (nMaskBits < 0) {
              return remoteAddress.equals(requiredAddress);
          }
  
          byte[] remAddr = remoteAddress.getAddress();
          byte[] reqAddr = requiredAddress.getAddress();
  
          int oddBits = nMaskBits % 8;
          int nMaskBytes = nMaskBits / 8 + (oddBits == 0 ? 0 : 1);
          byte[] mask = new byte[nMaskBytes];
  
          Arrays.fill(mask, 0, oddBits == 0 ? mask.length : mask.length - 1, (byte) 0xFF);
  
          if (oddBits != 0) {
              int finalByte = (1 << oddBits) - 1;
              finalByte <<= 8 - oddBits;
              mask[mask.length - 1] = (byte) finalByte;
          }
  
          for (int i = 0; i < mask.length; i++) {
              if ((remAddr[i] & mask[i]) != (reqAddr[i] & mask[i])) {
                  return false;
              }
          }
  
          return true;
      }
  
      private InetAddress parseAddress(String address) {
         try {
             return InetAddress.getByName(address);
         } catch (UnknownHostException e) {
             throw new IllegalArgumentException("Failed to parse address" + address, e);
         }
     }
 }