notes.txt

Vovida 社区开源的 SIP 协议源码

$Id: NOTES.txt,v 1.4.2.1 2003/03/28 05:25:57 bko Exp $

Technical information and notes on the SIP stack.


Known issues

1.  Quoted strings are not translated to users that is, users are
expected to pass quoted values to the system, e.g.

	 SipFrom from;

	 // note -- the next line is enough quotation to form the
	 // literal string \"SecondQuote\"
	 
	 from.setDisplayName("\\\"SecondQuote\\\"");


will produce the text

     From: \"SecondQuote\"

on encoding as the display-name.  this is in opposition to an
"idealized" system where the need to quote would be caught
automatically, and this would work:

	 // note -- the next line is enough quotation to form the
	 // literal string "SecondQuote" -- note there is no '\'
	 // character explicitly added to the text here.
	 
	 from.setDisplayName("\"SecondQuote\"");

producing the text

    From: \"SecondQuote\"

as the display name, but, when the user gets the display name for
printing, or something, they get

         "SecondQuote"

without having to match the \'s.

this isn't entirely needed, but it sure might be nice.

It is, however, needed for translating quoted URLs, e.g.

    sip:[e-mail]

being equal to

    sip:4000@%41%42%43.com



How To Add A New Header

In order to add a new header, you will have to take a few steps:

1.  You must create a new class, which derives publicly from SipHeader
(see SipHeader.hxx).

2.  You need to add a new SipHeaderType for the message.  See
SipHeader.hxx for where this should be done.  Add this in alphabetical
order, or you will have a lot of trouble later.  Make sure that
SIP_UNKNOWN_HDR is last -- sipHeaderNameCount, which sizes these
arrays, is equal to SIP_UNKNOWN_HDR + 1.

3.  You need to add an entry to the sipHeaderTable in SipHeader.cxx .
This is also in alphabetical order.  The entry you add needs to be in
the exact same place as the entry in SipHeaderType.  The
sipHeaderTable is used to populate the sipHeaderNames table, which is
used to determine which type a given sipHeader is.

4.  Fill out decodeHeader so that a new sipHeader can get constructed
based on a SipHeaderType.  If you have a new header named NewHeader,
with SipHeaderType SIP_NEW_HEADER_HDR, and class SipNewHeader, for the
text

    NewHeader: content of the new header

the function decodeHeader will be passed

    decodeHeader( SIP_NEW_HEADER_HDR, Data("content of the new header") );

and will expect back a new SipNewHeader object allocated on the heap.

5.  *IMPORTANT* You also need to fill out the sipHeaderOutputOrder
struct in SipRawHeaderContainer.cxx.  If you do not fill this out,
your header will never be printed.  This header specifies the order in
which the headers will be output when encode() is called.  The headers
which appear first in the sipHeaderOutputOrder will appear first,
while later ones will appear later.  note that sipHeaderOutputOrder
must contain all of the headers to be output -- if the header does not
appear in this struct, it will not be encoded.



======================================================================

Copyright 2000-2003, Cisco Systems, Inc.
THE INFORMATION HEREIN IS PROVIDED ON AN "AS IS" BASIS, WITHOUT ANY
WARRANTIES OR REPRESENTATIONS, EXPRESS, IMPLIED OR STATUTORY, INCLUDING
WITHOUT LIMITATION, WARRANTIES OF NONINFRINGEMENT, MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.

$Id: NOTES.txt,v 1.4.2.1 2003/03/28 05:25:57 bko Exp $