2-in-1 problem: Stream access and access violation


I'm trying to write a HTTP tunnel. My idea is to let a browser connect to a blocking serversocket, and administrate all data from the browser to the host in the thread, that is beeing spawned.

In the thread, I create a new TThread. This thread will then manage all responses from the proxy/HTTP server back to the browser.

In the TServerClientThread I create a new blocking socket (to connect to the HTTP/proxy server), but sometimes i get an access violation the setting Active:=True. Why?

Error is: Project nnnn raised exception class EAccessViolation with message 'Access Violation at address C000013C. Read of address C000013C'. ...

I also get '... 'Access Violation at address 00000000. Read of address 00000000'. ...

In the TServerClientThread I also create two WinSocketStream. One is beeing read from the TServerClientThread (HTTP requests) and written from the TThread (Answers from the HTTP/proxy server), and the other Stream works the otherway around.

Is this ok to do, without making any kind of mutual exclution? If not - how should this be done?
(I have not had any errors so far, but ...)

Hope to hear from you soon guys!


BTW: If anybody has some Delphi sourcecode for a network tunnel, I would really appreciate it.
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jeurkConnect With a Mentor Commented:
I suggest you take a look at the winshoes components.
They have the components you need :
tunnel master, and tunnel slave. they
is also a demo that show how to use things.
Get them on http://www.pbe.com/Winshoes
it's free and open source...

Let me know, if they is a problem...

As for Q1: Most likely the object has not been created, or it has been freed...


I have done something similar to what you want, but i found it was easier to use NonBlocking.
Regarding Q1 : I'm using TServerSocket (NonBlocking) and i remember that some "socket.close" commands actually close all open treads. Maybe something similar happen in your program.

Good luck
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jpvjAuthor Commented:
To Jeurk:

Hi again!

The Winshoes package looks very impressing, except for the (lack of) documentation!

Could you please explain, how the tunnel demo works?

Thanks in advance!

listening :-)
Where is a lack documentation ? ;)
ok. I agree.
This so well written that you don't need documentation.
You was trying to do some tunneling stuff, so you should understand what is going on ? no ?
To make the demo work : launch the server...
he will start to listen on host port 21.

After that, start a client, change th ip to, start it. The serveur will show you a connexion.
You cannot start more then on client on the same machine.

This how to do it the hard way. If you look at the components, you will see that they is a TMasterTunnel and a TSlaveTunnel.
They encapsulate all the fonctions you need...
jpvjAuthor Commented:
Hi Again!

Sorry for the long delay, but ... :-)

If have use the WinshoeMappedPort instead, and it work fine!

Thanks for your help!

jpvjAuthor Commented:
Comment accepted as answer
Glad I could help.
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