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/*
* Copyright (c) Contributors, http://opensimulator.org/
* See CONTRIBUTORS.TXT for a full list of copyright holders.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the OpenSimulator Project nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Net;
using Nwc.XmlRpc;
using OpenSim.Framework;
using log4net;
namespace OpenSim.Framework.Servers.HttpServer
{
public enum ThrottleAction
{
DoThrottledMethod,
DoThrow
}
public class XmlRpcBasicDOSProtector
{
private readonly XmlRpcMethod _normalMethod;
private readonly XmlRpcMethod _throttledMethod;
private readonly CircularBuffer<int> _generalRequestTimes; // General request checker
private readonly BasicDosProtectorOptions _options;
private readonly Dictionary<string, CircularBuffer<int>> _deeperInspection; // per client request checker
private readonly Dictionary<string, int> _tempBlocked; // blocked list
private readonly System.Timers.Timer _forgetTimer; // Cleanup timer
private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
private readonly System.Threading.ReaderWriterLockSlim _lockSlim = new System.Threading.ReaderWriterLockSlim();
public XmlRpcBasicDOSProtector(XmlRpcMethod normalMethod, XmlRpcMethod throttledMethod,BasicDosProtectorOptions options)
{
_normalMethod = normalMethod;
_throttledMethod = throttledMethod;
_generalRequestTimes = new CircularBuffer<int>(options.MaxRequestsInTimeframe + 1,true);
_generalRequestTimes.Put(0);
_options = options;
_deeperInspection = new Dictionary<string, CircularBuffer<int>>();
_tempBlocked = new Dictionary<string, int>();
_forgetTimer = new System.Timers.Timer();
_forgetTimer.Elapsed += delegate
{
_forgetTimer.Enabled = false;
List<string> removes = new List<string>();
_lockSlim.EnterReadLock();
foreach (string str in _tempBlocked.Keys)
{
if (
Util.EnvironmentTickCountSubtract(Util.EnvironmentTickCount(),
_tempBlocked[str]) > 0)
removes.Add(str);
}
_lockSlim.ExitReadLock();
lock (_deeperInspection)
{
_lockSlim.EnterWriteLock();
for (int i = 0; i < removes.Count; i++)
{
_tempBlocked.Remove(removes[i]);
_deeperInspection.Remove(removes[i]);
}
_lockSlim.ExitWriteLock();
}
foreach (string str in removes)
{
m_log.InfoFormat("[{0}] client: {1} is no longer blocked.",
_options.ReportingName, str);
}
_lockSlim.EnterReadLock();
if (_tempBlocked.Count > 0)
_forgetTimer.Enabled = true;
_lockSlim.ExitReadLock();
};
_forgetTimer.Interval = _options.ForgetTimeSpan.TotalMilliseconds;
}
public XmlRpcResponse Process(XmlRpcRequest request, IPEndPoint client)
{
// If these are set like this, this is disabled
if (_options.MaxRequestsInTimeframe < 1 || _options.RequestTimeSpan.TotalMilliseconds < 1)
return _normalMethod(request, client);
string clientstring = GetClientString(request, client);
_lockSlim.EnterReadLock();
if (_tempBlocked.ContainsKey(clientstring))
{
_lockSlim.ExitReadLock();
if (_options.ThrottledAction == ThrottleAction.DoThrottledMethod)
return _throttledMethod(request, client);
else
throw new System.Security.SecurityException("Throttled");
}
_lockSlim.ExitReadLock();
_generalRequestTimes.Put(Util.EnvironmentTickCount());
if (_generalRequestTimes.Size == _generalRequestTimes.Capacity &&
(Util.EnvironmentTickCountSubtract(Util.EnvironmentTickCount(), _generalRequestTimes.Get()) <
_options.RequestTimeSpan.TotalMilliseconds))
{
//Trigger deeper inspection
if (DeeperInspection(request, client))
return _normalMethod(request, client);
if (_options.ThrottledAction == ThrottleAction.DoThrottledMethod)
return _throttledMethod(request, client);
else
throw new System.Security.SecurityException("Throttled");
}
XmlRpcResponse resp = null;
resp = _normalMethod(request, client);
return resp;
}
// If the service is getting more hits per expected timeframe then it starts to separate them out by client
private bool DeeperInspection(XmlRpcRequest request, IPEndPoint client)
{
lock (_deeperInspection)
{
string clientstring = GetClientString(request, client);
if (_deeperInspection.ContainsKey(clientstring))
{
_deeperInspection[clientstring].Put(Util.EnvironmentTickCount());
if (_deeperInspection[clientstring].Size == _deeperInspection[clientstring].Capacity &&
(Util.EnvironmentTickCountSubtract(Util.EnvironmentTickCount(), _deeperInspection[clientstring].Get()) <
_options.RequestTimeSpan.TotalMilliseconds))
{
//Looks like we're over the limit
_lockSlim.EnterWriteLock();
if (!_tempBlocked.ContainsKey(clientstring))
_tempBlocked.Add(clientstring, Util.EnvironmentTickCount() + (int)_options.ForgetTimeSpan.TotalMilliseconds);
else
_tempBlocked[clientstring] = Util.EnvironmentTickCount() + (int)_options.ForgetTimeSpan.TotalMilliseconds;
_lockSlim.ExitWriteLock();
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, client.Address);
return false;
}
//else
// return true;
}
else
{
_deeperInspection.Add(clientstring, new CircularBuffer<int>(_options.MaxRequestsInTimeframe + 1, true));
_deeperInspection[clientstring].Put(Util.EnvironmentTickCount());
_forgetTimer.Enabled = true;
}
}
return true;
}
private string GetClientString(XmlRpcRequest request, IPEndPoint client)
{
string clientstring;
if (_options.AllowXForwardedFor && request.Params.Count > 3)
{
object headerstr = request.Params[3];
if (headerstr != null && !string.IsNullOrEmpty(headerstr.ToString()))
clientstring = request.Params[3].ToString();
else
clientstring = client.Address.ToString();
}
else
clientstring = client.Address.ToString();
return clientstring;
}
}
public class BasicDosProtectorOptions
{
public int MaxRequestsInTimeframe;
public TimeSpan RequestTimeSpan;
public TimeSpan ForgetTimeSpan;
public bool AllowXForwardedFor;
public string ReportingName = "BASICDOSPROTECTOR";
public ThrottleAction ThrottledAction = ThrottleAction.DoThrottledMethod;
}
}
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