a Client connection without Server accept() : possible ?

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2 total messages Started by didier Thu, 01 Jun 2006 12:29

#2278

Author: didier
Date: Thu, 01 Jun 2006 12:29

35 lines
2027 bytes

Hello everybody,

As guys here seem smart, is there any explanation to this fact :

1- I launch a TCP server (socket(AF_INET, SOCK_STREAM, 0)
+ bind + listen) and break my prog immediately AFTER completion
of listen(). So, the server is stopped here and shall NEVER 
accept() any connection.
NOTA : the server is programmed with VisualC++2005 (8.0)

2- I launch a TCP client (socket) 
NOTA : the client is programmed with Borland C++ 6.0 with the
VCL Lib (ClientSocket).

3- I press a button which sets the ClientSocket->Active flag
to "true". This is the only thing I do with this VCL component
to connect a client to a server (as far as I know).

RESULT : The client tells that the connection has been 
successfully established with the server. I verify this with
the flag ClientSocket->Socket->Connected = true !

The weird thing is that the server is breaked : which mechanism
has accepted the client socket connection ? Not the server !

I cannot find any explanation. It changes my view of the listen
function : it does not work as I believe... I thought that only
the accept() function validates the client connection request...

Any idea of test(s) to understand this behavior ?

Thanks.

didier

Re: a Client connection without Server accept() : possible ?

#2279

Author: Remy Lebeau (TeamB)
Date: Thu, 01 Jun 2006 17:44

25 lines
2044 bytes

"didier" <jehanno@lal.in2p3.fr> wrote in message
news:447eddb9$1@newsgroups.borland.com...

> RESULT : The client tells that the connection has been
> successfully established with the server. I verify this with
> the flag ClientSocket->Socket->Connected = true !

The Connected property is set to true as soon as the WinSock API connect()
function completes its work.

> I cannot find any explanation. It changes my view of the listen
> function : it does not work as I believe... I thought that only
> the accept() function validates the client connection request...

accept() provides a SOCKET handle to the server code to access the
connection.  The only explanation for what you see is that the connection
itself has been established when it is placed in the server socket's queue
that was created by listen().  The server socket knows the connection it
there, it just hasn't retreived it from the queue yet.  In the meantime,
listen() returned a response back to the client to let it know that the
connection was acknowledged.


Gambit

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