276 lines
12 KiB
C#
276 lines
12 KiB
C#
/*
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* Copyright (c) Contributors, http://opensimulator.org/
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* See CONTRIBUTORS.TXT for a full list of copyright holders.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the OpenSimulator Project nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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using System;
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using System.Collections.Generic;
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using System.Reflection;
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using log4net;
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namespace OpenSim.Framework
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{
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public class BasicDOSProtector
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{
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public enum ThrottleAction
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{
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DoThrottledMethod,
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DoThrow
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}
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private readonly CircularBuffer<int> _generalRequestTimes; // General request checker
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private readonly BasicDosProtectorOptions _options;
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private readonly Dictionary<string, CircularBuffer<int>> _deeperInspection; // per client request checker
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private readonly Dictionary<string, int> _tempBlocked; // blocked list
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private readonly Dictionary<string, int> _sessions;
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private readonly System.Timers.Timer _forgetTimer; // Cleanup timer
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private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
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private readonly System.Threading.ReaderWriterLockSlim _blockLockSlim = new System.Threading.ReaderWriterLockSlim();
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private readonly System.Threading.ReaderWriterLockSlim _sessionLockSlim = new System.Threading.ReaderWriterLockSlim();
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public BasicDOSProtector(BasicDosProtectorOptions options)
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{
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_generalRequestTimes = new CircularBuffer<int>(options.MaxRequestsInTimeframe + 1, true);
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_generalRequestTimes.Put(0);
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_options = options;
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_deeperInspection = new Dictionary<string, CircularBuffer<int>>();
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_tempBlocked = new Dictionary<string, int>();
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_sessions = new Dictionary<string, int>();
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_forgetTimer = new System.Timers.Timer();
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_forgetTimer.Elapsed += delegate
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{
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_forgetTimer.Enabled = false;
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List<string> removes = new List<string>();
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_blockLockSlim.EnterReadLock();
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foreach (string str in _tempBlocked.Keys)
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{
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if (
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Util.EnvironmentTickCountSubtract(Util.EnvironmentTickCount(),
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_tempBlocked[str]) > 0)
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removes.Add(str);
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}
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_blockLockSlim.ExitReadLock();
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lock (_deeperInspection)
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{
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_blockLockSlim.EnterWriteLock();
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for (int i = 0; i < removes.Count; i++)
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{
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_tempBlocked.Remove(removes[i]);
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_deeperInspection.Remove(removes[i]);
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_sessions.Remove(removes[i]);
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}
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_blockLockSlim.ExitWriteLock();
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}
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foreach (string str in removes)
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{
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m_log.InfoFormat("[{0}] client: {1} is no longer blocked.",
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_options.ReportingName, str);
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}
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_blockLockSlim.EnterReadLock();
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if (_tempBlocked.Count > 0)
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_forgetTimer.Enabled = true;
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_blockLockSlim.ExitReadLock();
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};
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_forgetTimer.Interval = _options.ForgetTimeSpan.TotalMilliseconds;
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}
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/// <summary>
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/// Given a string Key, Returns if that context is blocked
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/// </summary>
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/// <param name="key">A Key identifying the context</param>
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/// <returns>bool Yes or No, True or False for blocked</returns>
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public bool IsBlocked(string key)
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{
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bool ret = false;
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_blockLockSlim.EnterReadLock();
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ret = _tempBlocked.ContainsKey(key);
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_blockLockSlim.ExitReadLock();
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return ret;
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}
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/// <summary>
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/// Process the velocity of this context
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/// </summary>
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/// <param name="key"></param>
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/// <param name="endpoint"></param>
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/// <returns></returns>
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public bool Process(string key, string endpoint)
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{
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if (_options.MaxRequestsInTimeframe < 1 || _options.RequestTimeSpan.TotalMilliseconds < 1)
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return true;
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string clientstring = key;
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_blockLockSlim.EnterReadLock();
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if (_tempBlocked.ContainsKey(clientstring))
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{
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_blockLockSlim.ExitReadLock();
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if (_options.ThrottledAction == ThrottleAction.DoThrottledMethod)
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return false;
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else
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throw new System.Security.SecurityException("Throttled");
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}
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_blockLockSlim.ExitReadLock();
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lock (_generalRequestTimes)
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_generalRequestTimes.Put(Util.EnvironmentTickCount());
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if (_options.MaxConcurrentSessions > 0)
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{
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int sessionscount = 0;
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_sessionLockSlim.EnterReadLock();
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if (_sessions.ContainsKey(key))
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sessionscount = _sessions[key];
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_sessionLockSlim.ExitReadLock();
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if (sessionscount > _options.MaxConcurrentSessions)
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{
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// Add to blocking and cleanup methods
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lock (_deeperInspection)
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{
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_blockLockSlim.EnterWriteLock();
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if (!_tempBlocked.ContainsKey(clientstring))
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{
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_tempBlocked.Add(clientstring,
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Util.EnvironmentTickCount() +
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(int) _options.ForgetTimeSpan.TotalMilliseconds);
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_forgetTimer.Enabled = true;
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m_log.WarnFormat("[{0}]: client: {1} is blocked for {2} milliseconds based on concurrency, X-ForwardedForAllowed status is {3}, endpoint:{4}", _options.ReportingName, clientstring, _options.ForgetTimeSpan.TotalMilliseconds, _options.AllowXForwardedFor, endpoint);
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}
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else
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_tempBlocked[clientstring] = Util.EnvironmentTickCount() +
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(int) _options.ForgetTimeSpan.TotalMilliseconds;
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_blockLockSlim.ExitWriteLock();
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}
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}
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else
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ProcessConcurrency(key, endpoint);
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}
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if (_generalRequestTimes.Size == _generalRequestTimes.Capacity &&
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(Util.EnvironmentTickCountSubtract(Util.EnvironmentTickCount(), _generalRequestTimes.Get()) <
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_options.RequestTimeSpan.TotalMilliseconds))
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{
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//Trigger deeper inspection
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if (DeeperInspection(key, endpoint))
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return true;
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if (_options.ThrottledAction == ThrottleAction.DoThrottledMethod)
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return false;
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else
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throw new System.Security.SecurityException("Throttled");
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}
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return true;
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}
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private void ProcessConcurrency(string key, string endpoint)
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{
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_sessionLockSlim.EnterWriteLock();
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if (_sessions.ContainsKey(key))
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_sessions[key] = _sessions[key] + 1;
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else
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_sessions.Add(key,1);
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_sessionLockSlim.ExitWriteLock();
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}
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public void ProcessEnd(string key, string endpoint)
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{
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_sessionLockSlim.EnterWriteLock();
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if (_sessions.ContainsKey(key))
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{
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_sessions[key]--;
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if (_sessions[key] <= 0)
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_sessions.Remove(key);
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}
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else
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_sessions.Add(key, 1);
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_sessionLockSlim.ExitWriteLock();
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}
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/// <summary>
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/// At this point, the rate limiting code needs to track 'per user' velocity.
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/// </summary>
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/// <param name="key">Context Key, string representing a rate limiting context</param>
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/// <param name="endpoint"></param>
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/// <returns></returns>
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private bool DeeperInspection(string key, string endpoint)
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{
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lock (_deeperInspection)
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{
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string clientstring = key;
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if (_deeperInspection.ContainsKey(clientstring))
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{
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_deeperInspection[clientstring].Put(Util.EnvironmentTickCount());
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if (_deeperInspection[clientstring].Size == _deeperInspection[clientstring].Capacity &&
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(Util.EnvironmentTickCountSubtract(Util.EnvironmentTickCount(), _deeperInspection[clientstring].Get()) <
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_options.RequestTimeSpan.TotalMilliseconds))
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{
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//Looks like we're over the limit
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_blockLockSlim.EnterWriteLock();
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if (!_tempBlocked.ContainsKey(clientstring))
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_tempBlocked.Add(clientstring, Util.EnvironmentTickCount() + (int)_options.ForgetTimeSpan.TotalMilliseconds);
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else
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_tempBlocked[clientstring] = Util.EnvironmentTickCount() + (int)_options.ForgetTimeSpan.TotalMilliseconds;
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_blockLockSlim.ExitWriteLock();
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m_log.WarnFormat("[{0}]: client: {1} is blocked for {2} milliseconds, X-ForwardedForAllowed status is {3}, endpoint:{4}", _options.ReportingName, clientstring, _options.ForgetTimeSpan.TotalMilliseconds, _options.AllowXForwardedFor, endpoint);
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return false;
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}
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//else
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// return true;
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}
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else
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{
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_deeperInspection.Add(clientstring, new CircularBuffer<int>(_options.MaxRequestsInTimeframe + 1, true));
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_deeperInspection[clientstring].Put(Util.EnvironmentTickCount());
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_forgetTimer.Enabled = true;
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}
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}
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return true;
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}
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}
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public class BasicDosProtectorOptions
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{
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public int MaxRequestsInTimeframe;
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public TimeSpan RequestTimeSpan;
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public TimeSpan ForgetTimeSpan;
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public bool AllowXForwardedFor;
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public string ReportingName = "BASICDOSPROTECTOR";
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public BasicDOSProtector.ThrottleAction ThrottledAction = BasicDOSProtector.ThrottleAction.DoThrottledMethod;
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public int MaxConcurrentSessions;
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}
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}
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