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Re: [hybi] Review of draft-ietf-hybi-thewebsocketprotocol-13

Tobias Oberstein <tobias.oberstein@tavendo.de> Tue, 06 September 2011 14:57 UTC

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From: Tobias Oberstein <tobias.oberstein@tavendo.de>
To: "Richard L. Barnes" <rbarnes@bbn.com>, Iñaki Baz Castillo <ibc@aliax.net>
Date: Tue, 06 Sep 2011 07:58:34 -0700
Thread-Topic: [hybi] Review of draft-ietf-hybi-thewebsocketprotocol-13
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Cc: General Area Review Team <gen-art@ietf.org>, "hybi@ietf.org" <hybi@ietf.org>
Subject: Re: [hybi] Review of draft-ietf-hybi-thewebsocketprotocol-13
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> In contrast, *not* requiring breaking at UTF-8 code points means that clients
> can't do any meaningful validation on text frames.  Which means you might
> as well get rid of text frames entirely.

Why?

You can do streaming validation of UTF-8 without requiring frame boundaries to
observe UTF-8 code point boundaries.

In Python you can do that i.e. using

codecs.getincrementaldecoder('utf-8')()

When a frame does not end on code point boundary, one needs to remember
at most 3 bytes to continue validation on next frame.

It would make sense that a peer SHOULD fail a connection upon invalid UTF-8
as soon as it is possible - that means with at most 1 frame delay upon the
start of the byte sequence that was invalid UTF-8.

Anyway: what's the advantage of such an requirement?

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