* Move the BasicDOSProtector.cs to OpenSim.Framework (all useful classes belong there.....)

* Add an IsBlocked(string Key) method so it can be used more generically.   (think..   if we want to rate limit login failures, we could have a call in the Login Service to IsBlocked(uuid.ToString()) and ignore the connection if it returns true, if IsBlocked returns false, we could run the login information and if the login fails we could run the Process method to count the login failures.

1 files changed, 209 insertions, 0 deletions

diff --git a/OpenSim/Framework/BasicDOSProtector.cs b/OpenSim/Framework/BasicDOSProtector.cs
new file mode 100644
index 0000000..b470161
--- /dev/null
+++ b/OpenSim/Framework/BasicDOSProtector.cs
@@ -0,0 +1,209 @@
+/*
+ * 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 log4net;
+
+namespace OpenSim.Framework
+{
+   
+    public class BasicDOSProtector
+    {
+        public enum ThrottleAction
+        {
+            DoThrottledMethod,
+            DoThrow
+        }
+        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 BasicDOSProtector(BasicDosProtectorOptions options)
+        {
+            _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;
+        }
+
+        /// <summary>
+        /// Given a string Key, Returns if that context is blocked
+        /// </summary>
+        /// <param name="key">A Key identifying the context</param>
+        /// <returns>bool Yes or No, True or False for blocked</returns>
+        public bool IsBlocked(string key)
+        {
+            bool ret = false;
+             _lockSlim.EnterReadLock();
+            ret = _tempBlocked.ContainsKey(key);
+            _lockSlim.ExitReadLock();
+            return ret;
+        }
+
+        /// <summary>
+        /// Process the velocity of this context
+        /// </summary>
+        /// <param name="key"></param>
+        /// <param name="endpoint"></param>
+        /// <returns></returns>
+        public bool Process(string key, string endpoint)
+        {
+            if (_options.MaxRequestsInTimeframe < 1 || _options.RequestTimeSpan.TotalMilliseconds < 1)
+                return true;
+
+            string clientstring = key;
+
+            _lockSlim.EnterReadLock();
+            if (_tempBlocked.ContainsKey(clientstring))
+            {
+                _lockSlim.ExitReadLock();
+
+                if (_options.ThrottledAction == ThrottleAction.DoThrottledMethod)
+                    return false;
+                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(key, endpoint))
+                    return true;
+                if (_options.ThrottledAction == ThrottleAction.DoThrottledMethod)
+                    return false;
+                else
+                    throw new System.Security.SecurityException("Throttled");
+            }
+            return true;
+        }
+
+        /// <summary>
+        /// At this point, the rate limiting code needs to track 'per user' velocity.
+        /// </summary>
+        /// <param name="key">Context Key, string representing a rate limiting context</param>
+        /// <param name="endpoint"></param>
+        /// <returns></returns>
+        private bool DeeperInspection(string key, string endpoint)
+        {
+            lock (_deeperInspection)
+            {
+                string clientstring = key;
+
+
+                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, endpoint);
+
+                        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;
+        }
+
+    }
+
+
+    public class BasicDosProtectorOptions
+    {
+        public int MaxRequestsInTimeframe;
+        public TimeSpan RequestTimeSpan;
+        public TimeSpan ForgetTimeSpan;
+        public bool AllowXForwardedFor;
+        public string ReportingName = "BASICDOSPROTECTOR";
+        public BasicDOSProtector.ThrottleAction ThrottledAction = BasicDOSProtector.ThrottleAction.DoThrottledMethod;
+    }
+}