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Re: [MMUSIC] RFC 5245: ice-ufrags of length 256 vs stun maximum username length of 512 bytes

Philipp Hancke <fippo@goodadvice.pages.de> Fri, 16 August 2013 07:48 UTC

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Date: Fri, 16 Aug 2013 09:48:27 +0200
From: Philipp Hancke <fippo@goodadvice.pages.de>
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Subject: Re: [MMUSIC] RFC 5245: ice-ufrags of length 256 vs stun maximum username length of 512 bytes
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On Wed, 14 Aug 2013, Martin Thomson wrote:
> On 14 August 2013 07:54, Philipp Hancke <fippo@goodadvice.pages.de> wrote:
>>
>> Off by one?
>
> Maybe.  It certainly looks like an off-by-one error in the specs,
> though you could technically argue that both sets of length
> restrictions apply, since they are independent.  After all, not all
> users of the STUN username attribute are also doing ICE.

Right. I'd actually hope that implementations don't send anything longer 
than 512 bytes. I am not so sure about the comparison on the receiving 
end.
It's probably a good idea to mention this explicitly in 5245bis or
draft-ietf-mmusic-ice-sip-sdp though.

>> For ice-pwd this isn't a problem, right?
>
> This doesn't transit the network in STUN packets.  In SDP, the maximum
> size is 256 characters, but that's not a limit that other signaling
> protocols need to respect.

phew :-)

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