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    1   /*
    2    *  Licensed to the Apache Software Foundation (ASF) under one
    3    *  or more contributor license agreements.  See the NOTICE file
    4    *  distributed with this work for additional information
    5    *  regarding copyright ownership.  The ASF licenses this file
    6    *  to you under the Apache License, Version 2.0 (the
    7    *  "License"); you may not use this file except in compliance
    8    *  with the License.  You may obtain a copy of the License at
    9    *
    10   *    http://www.apache.org/licenses/LICENSE-2.0
    11   *
    12   *  Unless required by applicable law or agreed to in writing,
    13   *  software distributed under the License is distributed on an
    14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    15   *  KIND, either express or implied.  See the License for the
    16   *  specific language governing permissions and limitations
    17   *  under the License.
    18   *
    19   */
    20  package org.apache.mina.filter.firewall;
    21
    22  import java.net.InetSocketAddress;
    23  import java.net.SocketAddress;
    24  import java.util.Collections;
    25  import java.util.HashMap;
    26  import java.util.Map;
    27
    28  import org.apache.mina.core.filterchain.IoFilter;
    29  import org.apache.mina.core.filterchain.IoFilterAdapter;
    30  import org.apache.mina.core.session.IoSession;
    31  import org.slf4j.Logger;
    32  import org.slf4j.LoggerFactory;
    33
    34  /**
    35   * A {@link IoFilter} which blocks connections from connecting
    36   * at a rate faster than the specified interval.
    37   *
    38   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
    39   */
    40  public class ConnectionThrottleFilter extends IoFilterAdapter {
    41      private static final long DEFAULT_TIME = 1000;
    42
    43      private long allowedInterval;
    44
    45      private final Map<String, Long> clients;
    46
    47      private final static Logger LOGGER = LoggerFactory.getLogger(ConnectionThrottleFilter.class);
    48
    49      /**
    50       * Default constructor.  Sets the wait time to 1 second
    51       */
    52      public ConnectionThrottleFilter() {
    53          this(DEFAULT_TIME);
    54      }
    55
    56      /**
    57       * Constructor that takes in a specified wait time.
    58       *
    59       * @param allowedInterval
    60       *     The number of milliseconds a client is allowed to wait
    61       *     before making another successful connection
    62       *
    63       */
    64      public ConnectionThrottleFilter(long allowedInterval) {
    65          this.allowedInterval = allowedInterval;
    66          clients = Collections.synchronizedMap(new HashMap<String, Long>());
    67      }
    68
    69      /**
    70       * Sets the interval between connections from a client.
    71       * This value is measured in milliseconds.
    72       *
    73       * @param allowedInterval
    74       *     The number of milliseconds a client is allowed to wait
    75       *     before making another successful connection
    76       */
    77      public void setAllowedInterval(long allowedInterval) {
    78          this.allowedInterval = allowedInterval;
    79      }
    80
    81      /**
    82       * Method responsible for deciding if a connection is OK
    83       * to continue
    84       *
    85       * @param session
    86       *     The new session that will be verified
    87       * @return
    88       *     True if the session meets the criteria, otherwise false
    89       */
    90      protected boolean isConnectionOk(IoSession session) {
    91          SocketAddress remoteAddress = session.getRemoteAddress();
    92          if (remoteAddress instanceof InetSocketAddress) {
    93              InetSocketAddress addr = (InetSocketAddress) remoteAddress;
    94              long now = System.currentTimeMillis();
    95
    96              if (clients.containsKey(addr.getAddress().getHostAddress())) {
    97
    98                  LOGGER.debug("This is not a new client");
    99                  Long lastConnTime = clients.get(addr.getAddress().getHostAddress());
    100
    101                 clients.put(addr.getAddress().getHostAddress(), now);
    102
    103                 // if the interval between now and the last connection is
    104                 // less than the allowed interval, return false
    105                 if (now - lastConnTime < allowedInterval) {
    106                     LOGGER.warn("Session connection interval too short");
    107                     return false;
    108                 }
    109
    110                 return true;
    111             }
    112
    113             clients.put(addr.getAddress().getHostAddress(), now);
    114             return true;
    115         }
    116
    117         return false;
    118     }
    119
    120     @Override
    121     public void sessionCreated(NextFilter nextFilter, IoSession session) throws Exception {
    122         if (!isConnectionOk(session)) {
    123             LOGGER.warn("Connections coming in too fast; closing.");
    124             session.close(true);
    125         }
    126         nextFilter.sessionCreated(session);
    127     }
    128 }