Hi Pavitra,
Yes this is an ambiguity. However this is clarified in RFC-2616's (HTTP) section on
the accept-params. The media range params and the accept params are seperated by the
q parameter.
Cheers,
Prasanna
----- Original Message -----
From: Pavitra Krishnaswamy <[EMAIL PROTECTED]>
Date: Wednesday, September 17, 2003 8:51 am
Subject: [Sip] Ambiguity in the SIP ABNF
> Hi,
>
> There seems to be an ambiguity in the SIP ABNF
>
> See grammar below:
>
> ----------------------------------------------------------------
> accept-range = media-range *(SEMI accept-param)
> media-range = ( "*/*
> / ( m-type SLASH "*" )
> / ( m-type SLASH m-subtype )
> ) *( SEMI m-parameter )
>
> m-parameter = m-attribute EQUAL m-value
> m-attribute = token
> m-value = token / quoted-string
>
> accept-param = ("q" EQUAL qvalue) / generic-param
> qvalue = ( "0" [ "." 0*3DIGIT ] )
> / ( "1" [ "." 0*3("0") ] )
>
> generic-param = token [ EQUAL gen-value ]
> gen-value = token / host / quoted-string
>
> ----------------------------------------------------------------
>
>
> An instance of ambiguity is when the accept-range construct has the
> following structure -
>
> */*;abc=10;abc=10
>
> In the above text string, "*/*" is the first part of media-range.
>
> But what about the text which follows - ";abc=10" ? It conforms to the
> grammar of m-parameter (by the rule "m-attribute EQUAL m-value"
> which can be
> of the type "token EQUAL token"). BUT it also conforms to the
> grammar of
> accept-param (by the rule "generic-param" which can be of the type
> "tokenEQUAL token").
>
> Since *(SEMI m-parameter) as well as *(SEMI accept-param) can be
> optional,which grammar rules do the ";abc=10" texts belong to -
> the *(SEMI
> m-parameter) OR the *(SEMI accept-param)???
>
> One way to get around the ambiguity would be to change the rule for
> media-range as follows -
>
> media-range = ( "*/*
> / ( m-type SLASH "*" )
> / ( m-type SLASH m-subtype )
> ) *( HYPHEN m-parameter )
>
> Has anyone else faced this issue? Any help on this would be
> appreciated.
>
> Thanks,
> pavitra
>
>
>
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