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How to create a simple proxy in Managed C++

, 20 Apr 2002
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How to create a simple proxy to parse HTTP to another server using Managed C++
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Introduction

Many people have been asking me about a how to create a proxy. Actually is very simple to do in Managed C++. This article is made very simple, you can add as much as you want at the base class we can call it CHttpProxy

I'll be using the known class  TcpClient.

// Header File
// CHttpProxy.h 
__gc class CHttpProxy 
{ 
public: 
    CHttpProxy(String __gc *szHost, int port); 
    String __gc *m_host; 
    int m_port; 
    unsigned char SendToServer(unsigned char Packet __gc[]) __gc[]; 
};

// CHttpProxy.cpp
#using <mscorlib.dll>
#using <SYSTEM.DLL>
using namespace System;
using System::Net::Sockets::TcpClient;
using System::String;
using System::Exception;
using System::Net::Sockets::NetworkStream;
#include "httpproxy.h"

#include <stdio.h>

CHttpProxy::CHttpProxy(String __gc *szHost, int port)
{
    m_host = szHost;
    m_port = port;
    
}

unsigned char CHttpProxy::SendToServer(unsigned char    Packet __gc[]) __gc[]
{
    TcpClient * tcpclnt = new TcpClient();
    unsigned char bytes __gc[];  

    try
    {
        tcpclnt->Connect(m_host,m_port); 
    }

    catch (Exception  * e )
    {
        Console::WriteLine(e->ToString());
          return NULL;
    }

    // Send it
    if ( tcpclnt )
    {
        NetworkStream * networkStream =  tcpclnt->GetStream();

        int size = Packet->get_Length();        
        networkStream->Write(Packet, 0, size);

        bytes = new unsigned char __gc[tcpclnt->ReceiveBufferSize];
    
        networkStream->Read(bytes, 0, (int) tcpclnt->ReceiveBufferSize);

        return (bytes);
    }

    return (NULL);
}

Simple isn't it? This class creates a connection to the "real" IIS server.

So(...) How to use it now? Simpler than bowling water, you may remember this part of the code from my previous article:

TcpListener * pTcpListener;
TcpListener = new TcpListener(80);
TcpListener->Start(); 
TcpClient * pTcpClient; 
unsigned char  sendbytes __gc[];
pTcpClient = m_TcpListener->AcceptTcpClient();
NetworkStream * networkStream = pTcpClient->GetStream();
bytes = new unsigned char __gc[tcpCl->ReceiveBufferSize];
networkStream->Read(bytes, 0, (int) tcpCl->ReceiveBufferSize);

// Now we got the request
Console::WriteLine(S"Packet Received");            
CHttpProxy    *pProxy; 
pProxy    = new CHttpProxy(S"www.codeproject.com", 80);    // Goes somewhere else!
sendbytes = pProxy->SendToServer(bytes);
networkStream->Write(sendbytes, 0 , sendbytes->get_Length());
networkStream->Close();

We listen on port 80 for any connection. Anything that comes in that port is re-directed to www.codeproject.com It's actually a pretty easy concept. The most interesting part comes when you get the buffer. You got the control to remove images from the HTML or change the content on the fly.

In my next article will look into those possibilities.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

About the Author

Albert Pascual
Web Developer
United States United States
Al is just another Software Engineer working in C++, ASp.NET and C#. Enjoys snowboarding in Big Bear, and wait patiently for his daughters to be old enough to write code and snowboard.
 
Al is a Microsoft ASP.NET MVP
 
Blog

Comments and Discussions

 
GeneralMy vote of 2 PinmemberMember 911174714-Jun-12 10:38 
QuestionDownload link PinmemberKishan Hathiwala11-Jul-08 2:36 
GeneralVery good sample PinmemberMember 14036344-Jun-08 8:21 
QuestionSimpler than bowling water? Pinmembercoolman545329-Mar-07 2:35 
QuestionC# Example? Pinmemberplehxp15-Dec-05 23:35 
AnswerRe: C# Example? Pinmembersf4all19-May-06 9:25 
QuestionMain Class? Pinmembervalente1-Nov-03 11:22 
QuestionFor VC++? PinmemberKasper B5-May-02 11:53 
AnswerRe: For VC++? PinmemberAlbert Pascual6-May-02 6:00 

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