Path: utzoo!attcan!uunet!husc6!ukma!rutgers!ucsd!ucbvax!VAX.FTP.COM!jbvb
From: jbvb@VAX.FTP.COM (James Van Bokkelen)
Newsgroups: comp.protocols.tcp-ip.ibmpc
Subject: Re: Packet Driver questions
Message-ID: <8807251433.AA17741@vax.ftp.com>
Date: 25 Jul 88 14:33:16 GMT
References: <1221@sun.soe.clarkson.edu>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 21

if_number is somewhat of an appendix.  Due to other aspects of the design
(no handle on the send_pkt call), the only reasonable value is 0.

access_type() can return BAD_HANDLE when out of handles.  TYPE_INUSE is
intended for just that situation: someone else has already claimed either
the type specified or some superset of it.  NO_SPACE is intended for any
kind of resource exhaustion that makes the access_type() fail.

typelen is a parameter to allow for situations (802.2 packet headers is the
only case I can think of at the moment) where the match length varies.  With
802.2 headers, one application might want all packets with SSAP 1, and another
might want SSAP = 1, DSAP = 2, etc.  In conventional Blue-Book Ethernet,
typelen is effectively a constant, 2.

I hadn't throught about terminate() much.  Seems like a good idea to release
the handle, whether or not the call succeeds.  This would allow an application
to attempt to free up all memory by closing all its handles that way (although
if this succeeded, the packet driver would need to be re-started before another
network program could run).

jbvb