Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site oddjob.UUCP
Path: utzoo!watmath!clyde!cbosgd!ihnp4!oddjob!matt
From: matt@oddjob.UUCP (Matt Crawford)
Newsgroups: net.unix-wizards,net.lan
Subject: Re: STREAMS query
Message-ID: <995@oddjob.UUCP>
Date: Sat, 12-Oct-85 15:58:30 EDT
Article-I.D.: oddjob.995
Posted: Sat Oct 12 15:58:30 1985
Date-Received: Mon, 14-Oct-85 04:28:57 EDT
References: <471@enmasse.UUCP> <1699@brl-tgr.ARPA> <449@cheviot.uucp> <1542@hammer.UUCP> <2864@sun.uucp> <1554@hammer.UUCP>
Reply-To: matt@oddjob.UUCP (Matt Crawford)
Organization: U. Chicago, Astronomy & Astrophysics
Lines: 36
Xref: watmath net.unix-wizards:15223 net.lan:1088

In article <1554@hammer.UUCP> steveg@hammer.UUCP (Steve Glaser) writes:
>
>Actually, an example of what I had in mind here is the accept sequence
>on a passive open.  In 4.2 (TCP/IP) the syscall sequence in the server
>looks something like:
>	1. socket()	2. bind()	3. listen()	4. accept()
>
>The accept blocks till a connection request is received.  It returns
>new file descriptor representing the *open* connection.  If the server
>didn't really want to talk to somebody (say it only accepts conections
>from specific users), it would have to close the connection.  The
>client side has now seen a "connection succeed" followed by a "close
>connection".
>
>In the ISO transport layer (ISO TP4), the server has the option of
>rejecting the connection *before* the other end has seen its
>"connect()" succeed.  ...
>
>4.2 BSD does not support this cleanly. ...

I betcha two new ioctl's could give 4.2 the above functions.
Do a select() on a socket upon which you are listening and when
a connection is available apply new ioctl #1 to peek at the
address of the pending connection at the head of the listening
socket's so_q.  (Or getpeername() could be extended to provide
this information)  If the process does not want to accept it
can apply the second new ioctl to drop the pending connection.

Note that this will be useless in the INET domain because the
SYNs are ACK'd in tcp_input() whether or not accept() has been
called, so the other side sees it's connect() succeed as long
as the passive side has done a listen() and the queue of pending
connections is not full.
_____________________________________________________
Matt		University	crawford@anl-mcs.arpa
Crawford	of Chicago	ihnp4!oddjob!matt