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From: ktk@nas.nasa.gov (Katy T. Kislitzin)
Newsgroups: comp.unix.wizards
Subject: Looking for a piece of code which sets IP level options
Message-ID: <1991Apr30.010753.28400@nas.nasa.gov>
Date: 30 Apr 91 01:07:53 GMT
Sender: news@nas.nasa.gov
Organization: NAS Program, NASA Ames Research Center, Moffett Field, CA
Lines: 59

Hello--

I would like to see an example of a piece of code which constructs the
options field in the IP header.  I was under the impression that
traceroute had a "source route" option, but the version that I have
does not have such an option, nor does it seem to contain an example
of what I seek.  The version I have is from ftp.ee.lbl.gov:

#ifndef lint
static char *rcsid =
	"@(#)$Header: traceroute.c,v 1.17 89/02/28 21:01:13 van Exp $ (LBL)";
#endif

My understanding is that you do something like the following:

	char buf[OPTLEN + FUDGE];
	int s;

	if ( (s = socket(AF_INET, SOCK_RAW, proto) ) < 0 ){
		perror("socket");
		exit(1);
	}
	construct_options(buf);

	setsockopt(s, IPPROTO_IP, IP_OPTIONS, buf, sizeof(buf) );

What I am wondering is:
	
a) is the above the basic idea?

b) what do I put in buf?  

For concreteness, suppose I want to set a two hop loose source
route with myself as 1.1.1.1, the next hop as 2.2.2.2 and the
destination as 3.3.3.3.  I would infer that buf must contain the
following:

type len pointer route
 131  16    4    1.1.1.1 2.2.2.2 3.3.3.3

Is that correct?

Finally, does anyone know if IP_OPTIONS is supported under UNICOS 6.0?
The man pages have not proven illuminating.

Thanks in advance,

--kt

PS I am not really sure what group this belongs in.  It's a unix
question, not a tcp/ip question, so not comp.protocols.tcp-ip, but not
comp.unix.internals since I don't want to get inside the kernel, but
last time I posted this sort of question to comp.unix.programmers it
was like spitting in the wind.
--
Katy Kislitzin, ktk@nas.nasa.gov, ...!{ames, uunet}!nas.nasa.gov!ktk

[Moffett Field is in Mt. View California.  I live in the Santa Cruz
Mtns, approx 37deg08'N, 121deg59'W, 550m ]