Re: [manet] DLEP-17: Handling of unknown / unexpected messages

["Ratliff, Stanley" <[e-mail]>]

Henning,

As long as the overall message length isn’t screwed up, you’d be OK. Just take that value and “step over” the next <blah> octets in the incoming TCP stream…
that said, I must admit that I don’t like the idea. If the message is that messed up, this probably is the right time for the “nuclear option”. I just think we’ve gone a bit too far with all of the data items.

Regards,
Stan


From: Henning Rogge [mailto:[e-mail]]
Sent: Thursday, December 10, 2015 5:06 AM
To: MATTY, Steven <[e-mail]>
Cc: Stan Ratliff <[e-mail]>; Lou Berger <[e-mail]>; MANET IETF <[e-mail]>; [e-mail]
Subject: Re: [manet] DLEP-17: Handling of unknown / unexpected messages

On Thu, Dec 10, 2015 at 10:58 AM, MATTY, Steven <[e-mail]<mailto:[e-mail]>> wrote:
From: manet [mailto:[e-mail]] On Behalf Of Stan Ratliff

1) My inclination is towards the “Be generous in what you accept” side of things. But there is a trade-off when you
are being a friendly DLEP application that accepts any and all messages versus trying to ensure all DLEP
implementations are compliant. If you tear down the session whenever you get an invalid DLEP message then it
will become VERY obvious, VERY quickly that you are talking with a ‘bad’ implementation. However, let’s say that
this implementation on a router is no longer supported but is actually very useful in everything else it does right.

Would it be an option to introduce an [optional] NACK DLEP message type so that you can report to the sender
“Hey, you sent me this and something was up there” rather than just a silent discard?

The problem is you cannot be sure that the message was not malformed if something goes wrong... which means you don't know where to  start the next message in the incoming TCP stream.

Henning Rogge

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