Bill,
IMHO, it is a bad idea to ignore malformed ICMP extension structures without
discarding the entire ICMP message.
In the following cases, the recipient of a malformed message would respond to a
request without having completely understood it:
*
ICMP Echo Request
*
ICMP Extended Echo Request
In ICMP, as in life, this is risky business.
In all other cases, the recipient of the malformed ICMP message might inform
its client that it received a malformed ICMP message. However, it would be
unwise for the client to act upon incomplete information that it can glean from
the malformed message.
Ron
Juniper Business Use Only
________________________________
From: Bill Fenner <fen...@fenron.com>
Sent: Wednesday, August 13, 2025 7:08 PM
To: Ron Bonica <rbonica=40juniper....@dmarc.ietf.org>
Cc: The IESG <i...@ietf.org>; Gorry Fairhurst <go...@erg.abdn.ac.uk>;
draft-ietf-intarea-icmp-exten-hdr-...@ietf.org
<draft-ietf-intarea-icmp-exten-hdr-...@ietf.org>; intarea-cha...@ietf.org
<intarea-cha...@ietf.org>; int-area@ietf.org <int-area@ietf.org>
Subject: Re: [Int-area] Re: Gorry Fairhurst's Discuss on
draft-ietf-intarea-icmp-exten-hdr-len-05: (with DISCUSS and COMMENT)
[External Email. Be cautious of content]
On Wed, Aug 13, 2025 at 3:13 PM Ron Bonica
<rbonica=40juniper....@dmarc.ietf.org<mailto:40juniper....@dmarc.ietf.org>>
wrote:
(4) Please specify what the *receiver* action should be if the new length field
does not equal the sum of component objects. Is this malformed message
to be sliently discarded, the extension to be ignored (and what about
any following extensions), or something else?
(The TSV-ART review has more text that might be useful background).
[RB] I have added the following text:
[RB] The receiver MUST silently discard an ICMP message in the following
conditions:
Can we instead just pretend the ICMP extension isn't present if it's malformed,
but allow processing the ICMP message? If someone has a bug in their extension
generation, that'd be a bummer to completely prevent traceroute or path-MTU
discovery from working.
Thanks,
Bill
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