* Added a Basic DOS protection container/base object for the most common HTTP Server handlers. XMLRPC Handler, GenericHttpHandler and <Various>StreamHandler

* Applied the XmlRpcBasicDOSProtector.cs to the login service as both an example, and good practice.
* Applied the BaseStreamHandlerBasicDOSProtector.cs to the friends service as an example of the DOS Protector on StreamHandlers
* Added CircularBuffer, used for CPU and Memory friendly rate monitoring.
* DosProtector has 2 states, 1. Just Check for blocked users and check general velocity, 2. Track velocity per user,     It only jumps to 2 if it's getting a lot of requests, and state 1 is about as resource friendly as if it wasn't even there.

3 files changed, 35 insertions, 3 deletions

diff --git a/OpenSim/Server/Handlers/Asset/AssetServerGetHandler.cs b/OpenSim/Server/Handlers/Asset/AssetServerGetHandler.cs
index 8b23a83..0bd0235 100644
--- a/OpenSim/Server/Handlers/Asset/AssetServerGetHandler.cs
+++ b/OpenSim/Server/Handlers/Asset/AssetServerGetHandler.cs
@@ -42,14 +42,22 @@ using OpenSim.Framework.Servers.HttpServer;
 
 namespace OpenSim.Server.Handlers.Asset
 {
-    public class AssetServerGetHandler : BaseStreamHandler
+    public class AssetServerGetHandler : BaseStreamHandlerBasicDOSProtector
     {
         // private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
 
         private IAssetService m_AssetService;
 
         public AssetServerGetHandler(IAssetService service) :
-                base("GET", "/assets")
+                base("GET", "/assets",new BasicDosProtectorOptions()
+                                          {
+                                              AllowXForwardedFor = true,
+                                              ForgetTimeSpan = TimeSpan.FromSeconds(2),
+                                              MaxRequestsInTimeframe = 5,
+                                              ReportingName = "ASSETGETDOSPROTECTOR",
+                                              RequestTimeSpan = TimeSpan.FromSeconds(5),
+                                              ThrottledAction = ThrottleAction.DoThrottledMethod
+                                          })
         {
             m_AssetService = service;
         }
diff --git a/OpenSim/Server/Handlers/Login/LLLoginHandlers.cs b/OpenSim/Server/Handlers/Login/LLLoginHandlers.cs
index e4a0ffa..f2a5678 100644
--- a/OpenSim/Server/Handlers/Login/LLLoginHandlers.cs
+++ b/OpenSim/Server/Handlers/Login/LLLoginHandlers.cs
@@ -145,6 +145,17 @@ namespace OpenSim.Server.Handlers.Login
             return FailedXMLRPCResponse();
 
         }
+        public XmlRpcResponse HandleXMLRPCLoginBlocked(XmlRpcRequest request, IPEndPoint client)
+        {
+            XmlRpcResponse response = new XmlRpcResponse();
+            Hashtable resp = new Hashtable();
+
+            resp["reason"] = "presence";
+            resp["message"] = "Logins are currently restricted. Please try again later.";
+            resp["login"] = "false";
+            response.Value = resp;
+            return response;
+        }
 
         public XmlRpcResponse HandleXMLRPCSetLoginLevel(XmlRpcRequest request, IPEndPoint remoteClient)
         {
diff --git a/OpenSim/Server/Handlers/Login/LLLoginServiceInConnector.cs b/OpenSim/Server/Handlers/Login/LLLoginServiceInConnector.cs
index 97e8295..f60e892 100644
--- a/OpenSim/Server/Handlers/Login/LLLoginServiceInConnector.cs
+++ b/OpenSim/Server/Handlers/Login/LLLoginServiceInConnector.cs
@@ -44,6 +44,7 @@ namespace OpenSim.Server.Handlers.Login
 
         private ILoginService m_LoginService;
         private bool m_Proxy;
+        private BasicDosProtectorOptions m_DosProtectionOptions;
 
         public LLLoginServiceInConnector(IConfigSource config, IHttpServer server, IScene scene) :
                 base(config, server, String.Empty)
@@ -88,6 +89,16 @@ namespace OpenSim.Server.Handlers.Login
                 throw new Exception(String.Format("No LocalServiceModule for LoginService in config file"));
 
             m_Proxy = serverConfig.GetBoolean("HasProxy", false);
+            m_DosProtectionOptions = new BasicDosProtectorOptions();
+            // Dos Protection Options
+            m_DosProtectionOptions.AllowXForwardedFor = serverConfig.GetBoolean("DOSAllowXForwardedForHeader", false);
+            m_DosProtectionOptions.RequestTimeSpan =
+                TimeSpan.FromMilliseconds(serverConfig.GetInt("DOSRequestTimeFrameMS", 10000));
+            m_DosProtectionOptions.MaxRequestsInTimeframe = serverConfig.GetInt("DOSMaxRequestsInTimeFrame", 5);
+            m_DosProtectionOptions.ForgetTimeSpan =
+                TimeSpan.FromMilliseconds(serverConfig.GetInt("DOSForgiveClientAfterMS", 120000));
+            m_DosProtectionOptions.ReportingName = "LOGINDOSPROTECTION";
+            
 
             return loginService;
         }
@@ -95,7 +106,9 @@ namespace OpenSim.Server.Handlers.Login
         private void InitializeHandlers(IHttpServer server)
         {
             LLLoginHandlers loginHandlers = new LLLoginHandlers(m_LoginService, m_Proxy);
-            server.AddXmlRPCHandler("login_to_simulator", loginHandlers.HandleXMLRPCLogin, false);
+            server.AddXmlRPCHandler("login_to_simulator", 
+                new XmlRpcBasicDOSProtector(loginHandlers.HandleXMLRPCLogin,loginHandlers.HandleXMLRPCLoginBlocked,
+                    m_DosProtectionOptions).Process, false);
             server.AddXmlRPCHandler("set_login_level", loginHandlers.HandleXMLRPCSetLoginLevel, false);
             server.SetDefaultLLSDHandler(loginHandlers.HandleLLSDLogin);
             server.AddWebSocketHandler("/WebSocket/GridLogin", loginHandlers.HandleWebSocketLoginEvents);