content: /**
   * JBoss, Home of Professional Open Source
   * Copyright Red Hat, Inc., and individual contributors.
   *
   * 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.
   */
  package org.jboss.aerogear.unifiedpush.rest.util;
  
  import javax.servlet.http.HttpServletRequest;
  import java.util.regex.Pattern;
  
  /**
   * Helper for various tasks for working with {@link javax.servlet.http.HttpServletRequest} objects.
   */
  public final class HttpRequestUtil {
  
      private HttpRequestUtil() {
          // no-op
      }
  
      // from JSR 303
      private static final Pattern IP_ADDR_PATTERN = Pattern.compile("^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$");
  
      /**
       * Extracts the IP address from the given {@link javax.servlet.http.HttpServletRequest}.
       *
       * @param request to inspect
       *
       * @return the IP address from the given request
       */
      public static String extractIPAddress(final HttpServletRequest request) {
  
          String ip = request.getHeader("x-forwarded-for");
          if (isIPAdressValid(ip)) {
              return ip;
          }
          ip = request.getHeader("Proxy-Client-IP");
          if (isIPAdressValid(ip)) {
              return ip;
          }
          ip = request.getHeader("WL-Proxy-Client-IP");
          if (isIPAdressValid(ip)) {
              return ip;
          }
          return request.getRemoteAddr();
      }
  
      /**
       * Reads the "aerogear-sender" header to check if an AeroGear Sender client was used. If the header value is NULL
       * the value of the standard "user-agent" header is returned
       *
       * @param request to inspect
       *
       * @return value of header
       */
      public static String extractAeroGearSenderInformation(final HttpServletRequest request) {
          String client = request.getHeader("aerogear-sender");
          if (hasValue(client)) {
              return client;
          }
          // if there was no usage of our custom header, we simply return the user-agent value
          return request.getHeader("user-agent");
      }
  
      /**
       * Simple validation, using java.net.InetAddress.getByName().
       *
       * @param ip the IP address string to check
       *
       * @return true for a valid IP address
       */
      private static boolean isIPAdressValid(final String ip){
  
          // InetAddress.getByName() validates 'null' as a valid IP (localhost).
          // we do not want that
          if (hasValue(ip)) {
              return IP_ADDR_PATTERN.matcher(ip).matches();
          }
          return false;
      }
  
      private static boolean hasValue(final String value) {
          return value != null && !value.isEmpty();
      }
  }
  