BaseStreamHandlerBasicDOSProtector.cs

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 * See CONTRIBUTORS.TXT for a full list of copyright holders.
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 * modification, are permitted provided that the following conditions are met:
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 *       derived from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
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using OpenSim.Framework;
using System.IO;

namespace OpenSim.Framework.Servers.HttpServer
{
    public abstract class BaseStreamHandlerBasicDOSProtector : BaseRequestHandler, IStreamedRequestHandler
    {
       
        private readonly BasicDosProtectorOptions _options;
        private readonly BasicDOSProtector _dosProtector;

        protected BaseStreamHandlerBasicDOSProtector(string httpMethod, string path, BasicDosProtectorOptions options) : this(httpMethod, path, null, null, options) {}

        protected BaseStreamHandlerBasicDOSProtector(string httpMethod, string path, string name, string description, BasicDosProtectorOptions options)
            : base(httpMethod, path, name, description)
        {
            _options = options;
            _dosProtector = new BasicDOSProtector(_options);
        }

        public virtual byte[] Handle(
            string path, Stream request, IOSHttpRequest httpRequest, IOSHttpResponse httpResponse)
        {
            byte[] result;
            RequestsReceived++;
            string clientstring = GetClientString(httpRequest);
            string endpoint = GetRemoteAddr(httpRequest);
            if (_dosProtector.Process(clientstring, endpoint))
                result = ProcessRequest(path, request, httpRequest, httpResponse);
            else
                result = ThrottledRequest(path, request, httpRequest, httpResponse);
            if (_options.MaxConcurrentSessions > 0)
                _dosProtector.ProcessEnd(clientstring, endpoint);
            
            RequestsHandled++;

            return result;
        }

        protected virtual byte[] ProcessRequest(
            string path, Stream request, IOSHttpRequest httpRequest, IOSHttpResponse httpResponse)
        {
            return null;
        }

        protected virtual byte[] ThrottledRequest(
            string path, Stream request, IOSHttpRequest httpRequest, IOSHttpResponse httpResponse)
        {
            return new byte[0];
        }

        
        private string GetRemoteAddr(IOSHttpRequest httpRequest)
        {
            string remoteaddr = string.Empty;
            if (httpRequest.Headers["remote_addr"] != null)
                remoteaddr = httpRequest.Headers["remote_addr"];

            return remoteaddr;
        }

        private string GetClientString(IOSHttpRequest httpRequest)
        {
            string clientstring = string.Empty;

            if (_options.AllowXForwardedFor && httpRequest.Headers["x-forwarded-for"] != null)
                clientstring = httpRequest.Headers["x-forwarded-for"];
            else
                clientstring = GetRemoteAddr(httpRequest);

            return clientstring;
           
        }
    }
}