302 lines
10 KiB
C
302 lines
10 KiB
C
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/* $Id$ */
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/*
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* Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
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* Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef __PJSIP_REPLACES_H__
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#define __PJSIP_REPLACES_H__
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/**
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* @file sip_replaces.h
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* @brief SIP Replaces support (RFC 3891 - SIP "Replaces" Header)
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*/
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#include <pjsip/sip_msg.h>
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/**
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* @defgroup PJSIP_REPLACES SIP Replaces support (RFC 3891 - "Replaces" Header)
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* @ingroup PJSIP_HIGH_UA
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* @brief SIP Replaces support (RFC 3891 - "Replaces" Header)
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* @{
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*
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* This module implements support for Replaces header in PJSIP. The Replaces
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* specification is written in RFC 3891 - The Session Initiation Protocol (SIP)
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* "Replaces" Header, and can be used to enable a variety of features,
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* for example: "Attended Transfer" and "Call Pickup".
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*
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*
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*
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* \section PJSIP_REPLACES_USING_SEC Using PJSIP Replaces Support
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*
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* \subsection PJSIP_REPLACES_INIT_SUBSEC Initialization
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*
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* Application needs to call #pjsip_replaces_init_module() during application
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* initialization stage to register "replaces" support in PJSIP.
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*
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*
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*
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* \subsection PJSIP_REPLACES_UAC_SUBSEC UAC Behavior: Sending a Replaces Header
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*
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* A User Agent that wishes to replace a single existing early or
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* confirmed dialog with a new dialog of its own, MAY send the target
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* User Agent an INVITE request containing a Replaces header field. The
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* User Agent Client (UAC) places the Call-ID, to-tag, and from-tag
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* information for the target dialog in a single Replaces header field
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* and sends the new INVITE to the target.
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*
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* To initiate outgoing INVITE request with Replaces header, application
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* would create the INVITE request with #pjsip_inv_invite(), then adds
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* #pjsip_replaces_hdr instance into the request, filling up the Call-ID,
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* To-tag, and From-tag properties of the header with the identification
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* of the dialog to be replaced. Application may also optionally
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* set the \a early_only property of the header to indicate that it only
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* wants to replace early dialog.
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*
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* Note that when the outgoing INVITE request (with Replaces) is initiated
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* from an incoming REFER request (as in Attended Call Transfer case),
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* this process should be done rather more automatically by PJSIP. Upon
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* receiving incoming incoming REFER request, normally these processes
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* will be performed:
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* - Application finds \a Refer-To header,
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* - Application creates outgoing dialog/invite session, specifying
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* the URI in the \a Refer-To header as the initial remote target,
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* - The URI in the \a Refer-To header may contain header parameters such
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* as \a Replaces and \a Require headers.
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* - The dialog keeps the header fields in the header parameters
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* of the URI, and the invite session would add these headers into
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* the outgoing INVITE request. Because of this, the outgoing
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* INVITE request will contain the \a Replaces and \a Require headers.
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*
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*
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* For more information, please see the implementation of
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* #pjsua_call_xfer_replaces() in \ref PJSUA_LIB source code.
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*
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*
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* \subsection PJSIP_REPLACES_UAS_SUBSEC UAS Behavior: Receiving a Replaces Header
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*
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* The Replaces header contains information used to match an existing
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* SIP dialog (call-id, to-tag, and from-tag). Upon receiving an INVITE
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* with a Replaces header, the User Agent (UA) attempts to match this
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* information with a confirmed or early dialog.
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*
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* In PJSIP, if application wants to process the Replaces header in the
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* incoming INVITE request, it should call #pjsip_replaces_verify_request()
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* before creating the INVITE session. The #pjsip_replaces_verify_request()
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* function checks and verifies the request to see if Replaces request
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* can be processed. To be more specific, it performs the following
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* verification:
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* - checks that Replaces header is present. If not, the function will
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* return PJ_SUCCESS without doing anything.
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* - checks that no duplicate Replaces headers are present, or otherwise
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* it will return 400 "Bad Request" response.
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* - checks for matching dialog and verifies that the invite session has
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* the correct state, and may return 481 "Call/Transaction Does Not Exist",
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* 603 "Declined", or 486 "Busy Here" according to the processing rules
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* specified in RFC 3891.
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* - if matching dialog with correct state is found, it will give PJ_SUCCESS
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* status and return the matching dialog back to the application.
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*
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* The following pseudocode illustrates how application can process the
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* incoming INVITE if it wants to support Replaces extension:
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*
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\code
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// Incoming INVITE request handler
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pj_bool_t on_rx_invite(pjsip_rx_data *rdata)
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{
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pjsip_dialog *dlg, *replaced_dlg;
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pjsip_inv_session *inv;
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pjsip_tx_data *response;
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pj_status_t status;
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// Check whether Replaces header is present in the request and process accordingly.
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//
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status = pjsip_replaces_verify_request(rdata, &replaced_dlg, PJ_FALSE, &response);
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if (status != PJ_SUCCESS) {
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// Something wrong with Replaces request.
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//
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if (response) {
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pjsip_endpt_send_response(endpt, rdata, response, NULL, NULL);
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} else {
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// Respond with 500 (Internal Server Error)
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pjsip_endpt_respond_stateless(endpt, rdata, 500, NULL, NULL, NULL);
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}
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}
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// Create UAS Invite session as usual.
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//
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status = pjsip_dlg_create_uas_and_inc_lock(.., rdata, .., &dlg);
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..
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status = pjsip_inv_create_uas(dlg, .., &inv);
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// Send initial 100 "Trying" to the INVITE request
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//
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status = pjsip_inv_initial_answer(inv, rdata, 100, ..., &response);
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if (status == PJ_SUCCESS)
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pjsip_inv_send_msg(inv, response);
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// This is where processing is different between normal call
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// (without Replaces) and call with Replaces.
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//
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if (replaced_dlg) {
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pjsip_inv_session *replaced_inv;
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// Always answer the new INVITE with 200, regardless whether
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// the replaced call is in early or confirmed state.
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//
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status = pjsip_inv_answer(inv, 200, NULL, NULL, &response);
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if (status == PJ_SUCCESS)
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pjsip_inv_send_msg(inv, response);
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// Get the INVITE session associated with the replaced dialog.
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//
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replaced_inv = pjsip_dlg_get_inv_session(replaced_dlg);
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// Disconnect the "replaced" INVITE session.
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//
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status = pjsip_inv_end_session(replaced_inv, PJSIP_SC_GONE, NULL, &tdata);
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if (status == PJ_SUCCESS && tdata)
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status = pjsip_inv_send_msg(replaced_inv, tdata);
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// It's up to application to associate the new INVITE session
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// with the old (now terminated) session. For example, application
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// may assign the same User Interface object for the new INVITE
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// session.
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} else {
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// Process normal INVITE without Replaces.
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...
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}
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}
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\endcode
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*
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*
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* For a complete sample implementation, please see \a pjsua_call_on_incoming()
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* function of \ref PJSUA_LIB in \a pjsua_call.c file.
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*
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*
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* \section PJSIP_REPLACES_REFERENCE References
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*
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* References:
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* - <A HREF="http://www.ietf.org/rfc/rfc3891.txt">RFC 3891: The Session
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* Initiation Protocol (SIP) "Replaces" Header</A>
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* - \ref PJSUA_XFER
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*/
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PJ_BEGIN_DECL
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/**
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* Declaration of SIP Replaces header (RFC 3891).
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*/
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typedef struct pjsip_replaces_hdr
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{
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/** Standard header field. */
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PJSIP_DECL_HDR_MEMBER(struct pjsip_replaces_hdr);
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/** Call-Id */
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pj_str_t call_id;
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/** to-tag */
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pj_str_t to_tag;
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/** from-tag */
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pj_str_t from_tag;
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/** early-only? */
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pj_bool_t early_only;
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/** Other parameters */
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pjsip_param other_param;
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} pjsip_replaces_hdr;
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/**
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* Initialize Replaces support in PJSIP. This would, among other things,
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* register the header parser for Replaces header.
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*
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* @param endpt The endpoint instance.
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*
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* @return PJ_SUCCESS on success.
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*/
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PJ_DECL(pj_status_t) pjsip_replaces_init_module(pjsip_endpoint *endpt);
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/**
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* Create Replaces header.
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*
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* @param pool Pool to allocate the header instance from.
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*
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* @return An empty Replaces header instance.
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*/
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PJ_DECL(pjsip_replaces_hdr*) pjsip_replaces_hdr_create(pj_pool_t *pool);
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/**
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* Verify that incoming request with Replaces header can be processed.
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* This function will perform all necessary checks according to RFC 3891
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* Section 3 "User Agent Server Behavior: Receiving a Replaces Header".
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*
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* @param rdata The incoming request to be verified.
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* @param p_dlg On return, it will be filled with the matching
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* dialog.
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* @param lock_dlg Specifies whether this function should acquire lock
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* to the matching dialog. If yes (and should be yes!),
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* then application will need to release the dialog's
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* lock with #pjsip_dlg_dec_lock() when the function
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* returns PJ_SUCCESS and the \a p_dlg parameter is filled
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* with the dialog instance.
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* @param p_tdata Upon error, it will be filled with the final response
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* to be sent to the request sender.
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*
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* @return The function returns the following:
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* - If the request doesn't contain Replaces header, the
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* function returns PJ_SUCCESS and \a p_dlg parameter
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* will be set to NULL.
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* - If the request contains Replaces header and a valid,
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* matching dialog is found, the function returns
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* PJ_SUCCESS and \a p_dlg parameter will be set to the
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* matching dialog instance.
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* - Upon error condition (as described by RFC 3891), the
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* function returns non-PJ_SUCCESS, and \a p_tdata
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* parameter SHOULD be set with a final response message
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* to be sent to the sender of the request.
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*/
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PJ_DECL(pj_status_t) pjsip_replaces_verify_request(pjsip_rx_data *rdata,
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pjsip_dialog **p_dlg,
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pj_bool_t lock_dlg,
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pjsip_tx_data **p_tdata);
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PJ_END_DECL
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/**
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* @}
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*/
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#endif /* __PJSIP_REPLACES_H__ */
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