t_cancel.h

Go to the documentation of this file.

/*
 * $Id: t_cancel.h 4518 2008-07-28 15:39:28Z henningw $
 *
 * Copyright (C) 2001-2003 FhG Fokus
 *
 * This file is part of Kamailio, a free SIP server.
 *
 * Kamailio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 * Kamailio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License 
 * along with this program; if not, write to the Free Software 
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * History:
 * ---------
 *  2004-02-11  FIFO/CANCEL + alignments (hash=f(callid,cseq)) (uli+jiri)
 */

/*! \file
 * \brief TM :: CANCEL handling
 *
 * \ingroup tm
 * - Module: \ref tm
 */

#ifndef _CANCEL_H
#define _CANCEL_H

/*! \brief
   A buffer is empty but cannot be used by anyone else

   particularly, we use this value in the buffer pointer
   in local_buffer to tell "a process is already scheduled
   to generate a CANCEL, other processes are not supposed to"
   (which might happen if for example in a three-branch forking,
   two 200 would enter separate processes and compete for
   canceling the third branch); note that to really avoid
   race conditions, the value must be set in REPLY_LOCK
*/
#define BUSY_BUFFER ((char *)-1)

void which_cancel( struct cell *t, branch_bm_t *cancel_bm );
void cancel_uacs( struct cell *t, branch_bm_t cancel_bm );
void cancel_branch( struct cell *t, int branch );

int unixsock_uac_cancel(str* msg);

unsigned int t_uac_cancel(str *headers,str *body,
   unsigned int cancelledIdx,unsigned int cancelledLabel,
   transaction_cb cb, void* cbp);
typedef unsigned int (*tuaccancel_f)( str *headers,str *body,
   unsigned int cancelledIdx,unsigned int cancelledLabel,
   transaction_cb cb, void* cbp);

char *build_cancel(struct cell *Trans,unsigned int branch,
   unsigned int *len );

inline static short should_cancel_branch( struct cell *t, int b )
{
   int last_received;

   last_received = t->uac[b].last_received;
   /* cancel only if provisional received and no one else
      attempted to cancel yet */
   if ( t->uac[b].local_cancel.buffer.s==NULL ) {
      if ( last_received>=100 && last_received<200 ) {
         /* we'll cancel -- label it so that no one else
         (e.g. another 200 branch) will try to do the same */
         t->uac[b].local_cancel.buffer.s=BUSY_BUFFER;
         return 1;
      } else if (last_received==0) {
         /* set flag to catch the delaied replies */
         t->uac[b].flags |= T_UAC_TO_CANCEL_FLAG;
      }
   }
   return 0;
}


#endif