TCP connection

[Peter Lameijn]

At the moment I'm implementing a TCP server (DDT) in one of my programs. It needs to communicate with a third party client. (written in VC6). I'm testing at the moment with the echoserv and eclient examples. The problem:
- Eclient -> Echoserv : OK.
- Eclient -> VC6 test TCP server. : OK.
- VC6 client -> VC6 TCP server. : OK.
- VC6 client -> Echoserv : Does not work
VC6 client returns: connection is refused. (application uses Port 21000)

When I look with WinNT's netstat, it says that my TCP server listens on 71.31.1.1:21000 (my primary IP address), while the VC6 TCP server is said to listen on 0.0.0.0:21000 ???

Why???

-------------
Peter.



[This message has been edited by Peter Lameijn (edited June 24, 2000).]

[Peter Lameijn]

I've solved the above problem. It seems that while my TCP server listened on my primary IP address, the client was trying 127.0.0.1 .That raises another question: how do I setup a TCP server, if I don't know which IP address the client will use?
(both programs run on the same machine, and I don't have any influence on the clients IP choice...)

------------------
Peter.
mailto[email protected][email protected]</A>

[Troy King]

With the HOST ADDR statement you can retrieve the ip of the local machine. Then just use that number for both the server and the client. Or am I misunderstanding?

------------------
Troy King
[email protected]

[Florent Heyworth]

Hi Peter

the way to get a server to listen on all IP addresses is to bind() the server socket using %INADDR_ANY which has the value 0L.

All my winsock code uses the winsock api directly so I don't know if it's possible to do it using the PB winsock encapsulation - I suspect not.

Here's an example creating a server socket and binding it to an address:

FUNCTION PassiveSock( szService AS ASCIIZ , szTransport AS ASCIIZ, BYVAL lLen AS LONG) AS LONG
   LOCAL ptServent AS servent PTR
   LOCAL minsock_sa AS sockaddr_in
   LOCAL lSock AS LONG
   LOCAL lSockType AS LONG

   minsock_sa.sin_family = %AF_INET
   minsock_sa.sin_addr.s_addr = %INADDR_ANY

   'map service to port
   ptServent = getservbyname( szService, szTransport )
   IF ISTRUE( ptServent ) THEN
      minsock_sa.sin_port = htons( ntohs( @ptServent.s_port ) )
   ELSE
      minsock_sa.sin_port = htons( BYVAL VAL( szService ) )
      IF ISFALSE( minsock_sa.sin_port ) THEN
         STDOUT "Can't retrieve service: " + szService
         CALL WSACleanup()
         FUNCTION = %INVALID_SOCKET
         EXIT FUNCTION
      END IF
   END IF

   IF UCASE$(szTransport) = "UDP" THEN
      lSockType = %SOCK_DGRAM
   ELSE
      lSockType = %SOCK_STREAM
   END IF

   'socket allocation
   lSock = socket( %PF_INET, lSockType, 0 )

   IF lSock = %INVALID_SOCKET THEN
      STDOUT "Can't create socket"
      FUNCTION = %INVALID_SOCKET
      CALL WSACleanup()
      EXIT FUNCTION
   END IF

   'bind socket
   IF bind( lSock, minsock_sa, SIZEOF( minsock_sa) ) = %SOCKET_ERROR THEN
      STDOUT "Can't bind to port " + szService
      FUNCTION = %INVALID_SOCKET
      CALL WSACleanup()
      EXIT FUNCTION
   END IF

   IF ( lSock = %SOCK_STREAM AND listen( lSock, lLen ) = %SOCKET_ERROR ) THEN
      STDOUT "Can't listen on port: " + szService 
      FUNCTION = %INVALID_SOCKET
      CALL WSACleanup()
      EXIT FUNCTION
   END IF

   FUNCTION = lSock
END FUNCTION

Cheers

Florent



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[Peter Lameijn]

Thanks.

Troy:
I have no influence on the clients IP choice (third party program)
Florent:
I'm using the PB/DLL TCP xx functions, but I also don't know if it's possible this way to listen on all IP Addresses for a given port. If not, i'll have to go the API-way....

------------------
Peter.
mailto[email protected][email protected]</A>

[This message has been edited by Peter Lameijn (edited June 24, 2000).]

[Peter Lameijn]

Does anyone know if it's possible with TCP OPEN SERVER to let it listen for a given port on all IP addresses? (and not just on an address specified with ADDR xxxx)

------------------
Peter.
mailto[email protected][email protected]</A>