HttpHandlers and HttpModules

Re: Request.Filter

mulisak — Fri, 10 Jul 2009 08:10:31 GMT

I have got it working, see example here:

http://msdn.microsoft.com/en-us/library/system.web.httprequest.filter.aspx

If you need to do filtering in http module, use the code below.

My problem was that before attaching the filter I checked for HttpContext.Current.Request.InputStream.Length > 0 which must have had a side effect of reading the input stream and bypassing filtering.

   public class FilterHttpModule : System.Web.IHttpModule
    {
        void IHttpModule.Dispose()
        {
        }

        void IHttpModule.Init(HttpApplication context)
        {
            context.BeginRequest += this.BeginRequestHandler;
        }

        private void BeginRequestHandler(object sender, EventArgs args)
        {
            HttpContext.Current.Request.Filter = new QQQ1(HttpContext.Current.Request.Filter);
            HttpContext.Current.Request.Filter = new QQQ2(HttpContext.Current.Request.Filter);
        }
    }

Re: Request.Filter

mulisak — Fri, 10 Jul 2009 06:37:52 GMT

I have come across the same problem. Request.Filter is just not working, my custom stream class code is never called, though for Response.Filter it works ok.

Re: Request.Filter

unrealimhere — Thu, 25 Jun 2009 14:33:03 GMT

I was wondering if you have any advice on a problem I am seeing. I am creating an HttpModule where in the OnBeginRequest, I create a wrapper stream passing in the Request.Filter (I tried to pass in the Request.InputStream but when I run my application, I get an HttpException saying The request filter is not valid) into it and then set that wrapper stream as the filter doing something like Request.Filter = myWrapper. In my wrapper class I implement all the Stream methods, with the main one being of course the Read method where I was hoping to grab the bytes that are read and then write them out somewhere else. What is odd is I was expecting that when the InputStream was accessed (which I was doing in my test app in its Application_Begin_Request, it would be indirectly using my filter, but it does not. Is there anything else I need to enable in order for my wrapper class to be enabled as the Filter when InputStream is use on the Request?

Thanks in advance for any advice!

public class RequestLoggingFilter : IHttpModule
        protected void OnBeginRequest(object sender, EventArgs ea) {
            HttpApplication application = (HttpApplication)sender;
            HttpRequestLog httpRequestLog = new HttpRequestLog();
            application.Context.Items.Add("HttpRequestLog", httpRequestLog);
            WrapperInputStream wrapperInputStream = new WrapperInputStream(application.Request.Filter);
            httpRequestLog.WrapperInputStream = wrapperInputStream;
            application.Request.Filter = wrapperInputStream;
        }
.....
}


public class WrapperInputStream : Stream{

        public WrapperInputStream(Stream inputStream) {
            mInputStream = inputStream;
            if (inputStream.Length > 0) {
                mOutputStream = new MemoryStream((int)inputStream.Length);
            }
            else {
                mOutputStream = new MemoryStream();
            }
        }

        public override int Read(byte[] buffer, int offset, int count) {
            int readBytes = mInputStream.Read(buffer, offset, count);
            if (readBytes > 0) {
                mOutputStream.Write(buffer, offset, readBytes);
                mDataCaptureStarted = true;
                if (readBytes == count) {
                    mDataCaptureComplete = true;
                }
            }
            else {
                mDataCaptureComplete = true;
            }
            return readBytes;
        }
...
}

public class Global : System.Web.HttpApplication {
        protected void Application_BeginRequest(object sender, EventArgs e) {
            String mBody = "";
            Stream stream = ((HttpApplication)sender).Request.InputStream;
            int length = (int)stream.Length;
            logger.Info(length);
            try {
                byte[] bytes = new byte[length];
                stream.Read(bytes, 0, length);
                foreach (byte b in bytes) {
                    mBody += (Char)b;
                }
                //StreamReader reader = new StreamReader(((HttpApplication)sender).Request.InputStream);
                //mBody = reader.ReadToEnd();
                //reader.Close();
            }
            catch (Exception ex) {
                mBody = "Error decoding body: " + ex.Message;
            }
            logger.Info(mBody);
        }
...
}

Re: Request.Filter

Nai-Dong Jin - MSFT — Thu, 26 Feb 2009 02:51:15 GMT

Hi,

From your description, you're wanting to do some certain modification on the Request's InputStream and also you found using the Request Filter
HttpModule not worked, yes? If there is anything I misunderstood, please feel free to let me know.

Based on my experience, generally if we'd like to do some general operations on the Request's InputStream, the only way is just the Filter
httpMoudle. But this way may be somewhat complex because that means we need to directly deal with the raw byte stream of the Request. Here are some tech articles on using the HTTPMODULE to generate Fitler:

#Intercepting Filter
http://msdn.microsoft.com/library/en...erceptingFilte
r.asp?frame=true

#Implementing Intercepting Filter in ASP.NET Using HTTP Module
http://msdn.microsoft.com/library/en...erceptingFilte
rInASP.asp?frame=true

#Filtering HTTP Requests with .NET
http://www.ondotnet.com/pub/a/dotnet...ttpfilter.html

#HttpRequest.Filter Property
http://msdn.microsoft.com/library/en...WebHttpRequest
ClassFilterTopic.asp?frame=true

#Build an ASP.NET HttpRequest Log Filter
http://www.eggheadcafe.com/articles/20030813.asp

Request.Filter

k1fathi — Sat, 21 Feb 2009 12:58:14 GMT

Hi,all
I have some problem for changing 'Request.InputStream' with 'Request.Filter' or any other solution
how can I change my Request InputStream ? before sending data to server.

example:I wanna Replace the value "txt1" of asp.net textbox contorl coming from 'Request.InputStream',
by "txt2" that created in HttpModule Begin_Request handler ."txt2" must use instead of "txt1" before sending data to server!
is there any solution to change stream of 'Request.InputStream' by 'Request.Filter'???