I know it's complicated, but scanning text is necessarily part of determining 
which application/something+xml  you have.  I think (but should really check 
before saying this) that XML media type registrations describe what the DOCTYPE 
or XML namespace or root element are, and that, to properly "sniff" them, you'd 
have to scan text. But before you scan text, you have to determine charset.

So if we're going to support sniffing of media types in general, I don't see 
how we can do that without also specifying charset determination.



Larry
]

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of 
Adam Barth
Sent: Sunday, October 23, 2011 8:28 PM
To: Tobias Gondrom
Cc: [email protected]
Subject: Re: [websec] #22: content-type sniffing should include charset sniffing

The charset sniffing is also complicated by the fact that sometimes user agents 
need to parse some of the HTML to find a <meta> element.
In some situations, user agents need to restart the parsing algorithm, which is 
quite delicate and better to describe in the same document as HTML parsing (at 
least for use by HTML processing engines).

Adam


On Sun, Oct 23, 2011 at 8:24 PM, Tobias Gondrom <[email protected]> 
wrote:
> <hat="individual">
> I tend not to agree with that.
>
> The fact that charset sniffing might happen at the same time as 
> mime-sniffing does not seem like a strong argument to include this in 
> the draft.
>
> Furthermore I would rather have these issues separate:
> First you determine the content-type and then after that you may want 
> to determine the charset used within that content-type (if you really 
> have to sniff the charset). I can also imagine that charset sniffing 
> algorithm might be depending on the application identified by the 
> sniffed mime-type, which again would speak against throwing it in together 
> with mime-sniffing....
>
> Kind regards, Tobias
>
>
>
> On 24/10/11 00:55, websec issue tracker wrote:
>>
>> #22: content-type sniffing should include charset sniffing
>>
>>  the HTML5 spec contains some algorithms for sniffing charset, 
>> overriding
>>  labeled charset, etc.
>>
>>  MIME parameters like charset are as much a part of the content-type 
>> as the
>>  base internet media type, and any sniffing of parameters and other
>>  metadata (overriding content-type or guessing where it is not 
>> supplied or
>>  wrong) should be included in this document, since the sniffing will 
>> happen
>>  at the same time.
>>
>
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