NetNews Usenet Archive 1992 #18/NN_1992_18.iso/spool/comp/sys/sgi/12730

Internet Message Format | 1992-08-21 | 2.6 KB

Xref: sparky comp.sys.sgi:12730 comp.unix.wizards:3668
Path: sparky!uunet!dtix!darwin.sura.net!jvnc.net!nj.nec.com!cliff
From: [e-mail] (yep just another Xer)
Newsgroups: comp.sys.sgi,comp.unix.wizards
Subject: can you set timeout on portmapper clnt_create() ?
Summary: want to query random hosts with RPC without waiting
Keywords: rpc clnt_create portmap timeout
Message-ID: <[e-mail]>
Date: 21 Aug 92 18:04:43 GMT
Sender: [e-mail]
Organization: NEC Research Institute
Lines: 38
Originator: cliff@magic

hi,
i'm writing some packet analyzer/statistics-gathering code.  i am trying
to identify packet types down to the rpc level (i.e. nfs, ypserv, etc.).
to do this i make a query to the portmapper of each new host that appears
as a source of new packets, and essentially what i want is to call
pmap_getmaps().  however, we have a heterogenous network with some PC's
and Macs on it, and although these machines talk telnet and ftp, they
don't talk rpc (and hence have no portmapper to talk to).  so the program
hangs whenever a PC or Mac sends a packet, because the program tries
to establish a connection with the portmapper on the remote host, which
of course doesn't exist on PC's/Macs.

i know, one way to avoid this is to not make the portmap call to the PC/Mac.
but what i'd really like to do is to be able to just have a timeout (say
just 2 seconds instead of the default 25 [who set *that* value anyway??])
to the call so that if the client doesn't answer, the program can just
ignore that host and continue functioning.  also, i'll need this in case
i get into a situation of trying to contact the portmapper of a UNIX host
that just crashed.

i tried to do this, unsuccessfully, by using the "middle level" of rpc,
with a statement such as cl=clnt_create(argv[1],PMAP_PROG,PMAP_VERS,"udp").
however, i don't see any way to establish a timeout on the initial
client creation.

do i have to go all the way down to XDR (ugh!) or am i already making
the code to complicated?  this is my first time programming RPC, so it's
not too clear if i'm going in the right direction.  i succeeded in writing
a program that duplicates /usr/etc/rpcinfo -p host, but that just uses
the default interface pmap_getmaps().  clnt_create() works fine if the
host has a portmapper, but hangs otherwise.

please route any suggestions to [e-mail].  thanks.
--
--
[e-mail]    609-951-2688    fax [phone]
[Cliff Miller, 80% RA, 20% ESA (research associate & ergodic systems-analyst)]
NEC Research Institute, 4 Independence Way, Princeton NJ 08540