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From: Bob Walsh <walsh@bbn-labs-b>
Newsgroups: net.unix-wizards
Subject: Re: 4.2 ip source route bug?
Message-ID: <7672@brl-tgr.ARPA>
Date: Thu, 24-Jan-85 09:24:16 EST
Article-I.D.: brl-tgr.7672
Posted: Thu Jan 24 09:24:16 1985
Date-Received: Mon, 28-Jan-85 06:57:37 EST
Sender: news@brl-tgr.ARPA
Organization: Ballistic Research Lab
Lines: 28


The distributed 4.2 source routing is not properly done.  A source
routed packet looks like:

	IP header
			dst	128.11.1.1
	---------------------------------------
	IP options
				8.7.0.2
				9.9.9.9  <-
				192.23.2.1

The if_ifwithaddr() check should see if the IP header destination field
is on the current host.  It improperly checks to see if the next hop is
the current host.  It should:

		Is the current host 128.11.1.1 => if_ifwithaddr(128.11.1.1)

No, and strict source routing => ICMP error message
No, and loose source routing  => forward packet

Yes.  IP dst gets 9.9.9.9.  Store outgoing interface where 9.9.9.9 was.
Bump option pointer up by sizeof(struct in_addr).  If we're not on the
network of the new destination and it's a strictly source routed packet,
then generate an ICMP error message.  Otherwise, forward it.


bob walsh