Re: Intercept Outgoing Port 80 - C# Discussion Boards

13-Jun-07 11:00

I would like to intercept outgoing port 80 connections, redirect the http request, and inject the response back into the stream as if it had never been redirected.

Each time a user desires a web page, he transmits a request to a web server, and the web server transmits a response back to the user. Let us assume that user A is only able to access the IP address of user B, but user B is able to access the IP addresses of everybody. If user A desires a web page from someone other than user B, he will be unable to. The solution is as follows.

When user A requests a web page, instead of sending the request directly to the web server, the request is sent to user B. User B then requests the same request from the web server, and receives the corresponding response. That response is then sent back to user A.

To user A, it appears as if the request and response were completed with out having to send packets to user B. This is because all of the tunneling work goes on in the background. User A does not need to configure his web browser to connect to a certain proxy. Instead, when user A requests a certain page from a web server, a program running on user A's computer intercepts that request, does the necessary tunneling to user B, and finally injects the response back into user A's tcp stack, as if user A had himself contacted the web server.

I do not want to use a normal proxy. This all needs to occur in the background. The problem is implementing the previous paragraph. How do I tap into the windows tcp stack like that? I know that Google Desktop does it to modify search results, so it is definitely possible.

How do I do this? Sample code anyone? Sample projects? Any articles that have been written on this? Any help is welcomed.

Jason Donenfeld
ZX2C4 Software

Not Active13-Jun-07 11:06

13-Jun-07 11:06

only two letters away from being an asset

zx2c413-Jun-07 11:08

13-Jun-07 11:08

Real answers would be appreciated.

Please note -- this is not for any malicious purpose. This is for a legit project. Look at Google's use of this idea, for example.

Not Active13-Jun-07 13:59

13-Jun-07 13:59

Please explain how and where google has used this idea. I don't remember allowing any components to be installed on my system from the google website.

only two letters away from being an asset

zx2c413-Jun-07 14:02

13-Jun-07 14:02

Things are slightly different but essentially the same in theory.

When you install google desktop and make a search on google.com, the following happens:

You contact google.com and ask for search results. Google sends you an http response. Before returning to your browser, google desktop running on your system MODIFIES the response to add possible local queries and a link on the top that says "Desktop" (next to images groups etc).

Not Active13-Jun-07 14:06

13-Jun-07 14:06

Oh Google Desktop. That is certainly different than Google, the website. Guess it pays to clarify your post.

Sorry, don't use it.

only two letters away from being an asset

zx2c413-Jun-07 14:07

13-Jun-07 14:07

Any ideas how I can accomplish the task at hand?

Colin Angus Mackay13-Jun-07 23:52

Colin Angus Mackay

13-Jun-07 23:52

I've done this once before by writing an NDIS Driver. That was many years ago and it certainly isn't possible in C#

The basic idea of an NDIS Driver is that it sits and monitors raw packets as they go to and from your network card and allows you an opportunity to drop, modify or permit the packet through. It operates at a very low level and you MUST understand how individual packets are stitched together at the network level (lower level than TCP or IP) because that is all you will see. You will not see a nice stream of data for one connection, you will see everything regardless of how fragmented it is.

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Member 368719016-Jul-09 23:05

Member 3687190

16-Jul-09 23:05

Hi I have exactly the same problem. Have you find any answer

open text file in a textbox and print it

Colin Angus Mackay17-Jul-09 1:33

Colin Angus Mackay

17-Jul-09 1:33

Write an NDIS driver to intercept the data at the packet level. You cannot do that in C# tho'

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GDI+ Text Rendering

Akin Ocal13-Jun-07 10:55

Akin Ocal

13-Jun-07 10:55

Hello , i have some problems when i am in fullscreen. First text was good in quality but it had problems in characters' edges , so i looked for GDI+ info and found this :

g.TextRenderingHint= System.Drawing.Text.TextRenderingHint.AntiAlias ;

Antialising made it better in edges , but it looked worse this time , it looked fogged ( i am not sure that it is the correct word)

How can i fix it ?
The code is below :

public StringFormat GetStringFormat()
{
int numChars = m_String.Length;
CharacterRange[] characterRanges = new CharacterRange[numChars];
Region[] stringRegions = new Region[numChars];
for (int i = 0; i < numChars; i++)
characterRanges[i] = new CharacterRange(i, 1);
StringFormat stringFormat = new StringFormat();
stringFormat.FormatFlags = StringFormatFlags.NoClip;
stringFormat.SetMeasurableCharacterRanges(characterRanges);
return stringFormat;
}

public void DrawText(double SampleTime, IntPtr pBuffer, int BufferLen)
{
Rectangle rec = this.ClientRectangle;

g = Graphics.FromImage(bitmapOverlay);
g.Clear(Color.Transparent);

g.SmoothingMode = SmoothingMode.HighQuality ;
g.TextRenderingHint= System.Drawing.Text.TextRenderingHint.AntiAlias ;

d = g.MeasureString(m_String, fontOverlay);

if (boolshadow == true)
{
SolidBrush myBrush = new SolidBrush (Color.Black );
g.DrawString(m_String, fontOverlay, myBrush, stringXPos + strshadow, stringYPos + strshadow);// System.Drawing.StringFormat.GenericTypographic

}
g.DrawString(m_String, fontOverlay, brush, stringXPos, stringYPos, System.Drawing.StringFormat.GenericDefault);

if (logo != null)
{
int xpos = (int)logoXPos;
int ypos = (int)logoYPos;
Rectangle dstRect = new Rectangle(xpos, ypos, logo.Width, logo.Height);

Rectangle r = Screen.PrimaryScreen.WorkingArea;
//MessageBox.Show(r.Width.ToString());
//MessageBox.Show(r.Height.ToString());

g.DrawImage(logo, dstRect,0,0, logo.Width, logo.Height, GraphicsUnit.Pixel, attr);
}
bitmapOverlay.RotateFlip(RotateFlipType.RotateNoneFlipY);
Bitmap v = new Bitmap(lWidth, lHeight, videoStride, System.Drawing.Imaging.PixelFormat.Format32bppPArgb, pBuffer);
g = Graphics.FromImage(v);
g.DrawImage(bitmapOverlay, 0, 0, lWidth, lHeight);
g.Dispose();
v.Dispose();
}

merwa13-Jun-07 9:06

merwa

13-Jun-07 9:06

hi all
Can any one tell me how to open a text file in a text box and print the file contant

merwa

Re: open text file in a textbox and print it

Not Active13-Jun-07 11:21

13-Jun-07 11:21

using(TextReader reader = new StreamReader("myfile.txt"))<br />
{<br />
  textbox.text = reader.ReadToEnd();<br />
}

Printing is a little more involved. You need to have a PrintDocument and handle the PrintPage event.

http://msdn2.microsoft.com/en-us/library/system.drawing.printing.printdocument.aspx[^]

only two letters away from being an asset

Good C# Language Book

DVeit13-Jun-07 8:54

DVeit

13-Jun-07 8:54

Haven't had much luck searching for this in the forums or online. I've done some programming in VB.NET and want to make the jump to C#. A lot of the beginning C# books are a little too introductory. I'm wondering if anyone has a recommendation for a book that is more focused on learning the language, syntax, and features of the language rather than a ground up intro to the .Net framework, OOP, etc... Any insight/recommendations would be greatly appreciated.

MatrixCoder13-Jun-07 9:22

MatrixCoder

13-Jun-07 9:22

Illustrated C# 2005 or any Apress books are good.

Trinity: Neo... nobody has ever done this before.
Neo: That's why it's going to work.

DVeit14-Jun-07 4:07

DVeit

14-Jun-07 4:07

Thank you, this looks like just the type of book I was looking for. Ended up picking up this as well as Windows Forms Programming in C#. Thank you all for the help.

MidwestLimey13-Jun-07 9:26

MidwestLimey

13-Jun-07 9:26

If in doubt use {}, end everything with ; and never ever captilize the first letter, ever Wink | ;)

Seriously though, if you're comfortable and familiar with the framework and concepts of OO it won't be that hard.

I have an idea to help though. The following is a pretty good code converter, try writing VB stuff and see how it looks in C#:

http://www.carlosag.net/Tools/CodeTranslator/Default.aspx[^]

Doesn't do generics though.

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I'm largely language agnostic -

After a while they all bug me WTF | :WTF:

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Luc Pattyn13-Jun-07 9:53

Luc Pattyn

13-Jun-07 9:53

MidwestLimey wrote:
never ever captilize the first letter

you may need an Application, a Form, a Console, and many more Controls... Laugh | :laugh:

Luc Pattyn

[My Articles] [Forum Guidelines]

MidwestLimey13-Jun-07 9:59

MidwestLimey

13-Jun-07 9:59

addendum:
Use capitals only when forced to by the bloody framework and never make clear in 5 lines that which can be in-lined in one Big Grin | :-D

Welcome to the C# club.

------------------------------------------------
I'm largely language agnostic -

After a while they all bug me WTF | :WTF:

------------------------------------------------

leckey13-Jun-07 10:42

leckey

13-Jun-07 10:42

Starting out with C++ by Tony Gaddis ISBN 9780321409393

This is what we used in college and has nothing about .NET and such (at least the older version anyhow. We used the 3rd edition but I know there has been at least one more edition since then.)

This is a great book for anyone who has little to no programming experience.

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Giorgi Dalakishvili13-Jun-07 11:03

Giorgi Dalakishvili

13-Jun-07 11:03

C#: The Complete Reference by Herbert Schildt[^]

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