Hi, according to BNF syntax the following From is invalid since "tag" param 
must be a 'token' and not a 'quoted-string':

  From: <sip:al...@domain>;tag="invalid-quoted-string"

But SIP BNF grammar also states that header parameters can include hexadecimal 
escaping ( tag == t%61g ), so the following will be also invalid:

  From: <sip:al...@domain>;t%61g="invalid-quoted-string"


Ok, I'm building a parser and I am strict in the first case but implementing 
the second case is really a pain for any parser! I'm sure that no parser in 
the world would set as invalid the second case (instead it would 
assume "t%61g" is a generic extension parameter so it allows 'token' 
or 'quoted-string' as value).

I really wonder why hexadecimal escaping is allowed in *core* header 
parameters (as "From" tag). Any useful reason?

Thanks.


-- 
Iñaki Baz Castillo

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