Hi All,
As discussed below

> Via:    \r\n
>         SIP/2.0    \r\n
>                          /[transport]
[local_ip]:[local_port];branch=[branch]\r\n

is valid as per ABNF. What is the reasoning behind defining CRLF as part of
HCOLON ? Why it is allow by rfc 3261 to send someone **via** like above
with CRLFs ? Please share any usecase scenario.

Thanks & Regards,
Sachin Rastogi






On Mon, Apr 15, 2013 at 4:36 PM, Brett Tate <[email protected]> wrote:

> > Is the below message correct or not?
>
> Yes.  HCOLON and SLASH accommodate the atypical useless line wrapping and
> tabs of your example.
>
>
> > Via:    \r\n
> >         SIP/2.0    \r\n
> >                          /[transport]
> [local_ip]:[local_port];branch=[branch]\r\n
>
> <snip>
>
> > From the above syntax it seems that CRLF is possible
> > in the above syntax of Via message header after the ":".
> > Is my understanding correct or is there some error in
> > understanding the ABNF grammer ?
>
> Yes; you are correct as the RFC 3261 ABNF and text indicates.
>
>  "To separate the header name from the rest of value, a colon is used,
>   which, by the above rule, allows whitespace before, but no line
>   break, and whitespace after, including a linebreak.  The HCOLON
>   defines this construct."
>
>   Via  =  ( "Via" / "v" ) HCOLON via-parm *(COMMA via-parm)
>   HCOLON  =  *( SP / HTAB ) ":" SWS
>
>
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