[SIPForum-discussion] help:Header Field Format?

Herve Jourdain herve.jourdain at mstarsemi.com
Sat Dec 22 12:30:48 UTC 2007


Hi,

 

Sorry to answer quite late, hope it still can help…

 

For the colon(“:”), it’s a HCOLON, defined as:

HCOLON = *(SP / HTAB) “:” SWS

SWS = [LWS]

LWS = [*WSP CRLF] 1*WSP

 

So basically, the “whitespace” BEFORE the actual colon can be any amount
of SP or HTAB (or a combination), but NO CRLF.

And the “whitespace” AFTER the column can be any amount of SP or HTAB or
CRLF (or a combination), up to the point where you get a “whitespace” (SP
or HTAB) not followed by CRLF or another WSP…

 

For your other question, I tried to answer in another email.

 

Regards,

 

Herve

 

  _____  

From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of ? ?
Sent: mercredi 19 décembre 2007 14:55
To: discussion at sipforum.org
Subject: [SIPForum-discussion] help:Header Field Format?

 

Hi, all

Now , I meet a big problem in the SIP message parsing―the structure of
header field:

 

1.  field-name :  field-value

on either side of the colon(":"), the arbitrary amount of whitespace is
unlimited in theory. So what does the “whitespace” mean? a SP or HTAB?

 

2. a folding field-value

   If the SIP header field values be folded onto multiple lines. 

For instance,

   Subject: This is a test    =>     Subject: This
                                        is a test
 
So on the two lines, which kind of character will follow the word “This"
and "test"as an end of each line?
Is there still a CRLF? before interpreting the field value of “Subject”,
should I use a single SP instead of  all the special spaces between “This”
and “is”?
 
Moreover, is there any possible that these following fields to be split into
a multiple line representation? 
          Call-ID, CSeq, From, Context-Type

 

Merry Christmas!

 

Nora

 

  

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