// vim: noet sw=4 ts=4:
/*
==================================================================================
    Copyright (c) 2020 Nokia
    Copyright (c) 2020 AT&T Intellectual Property.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
==================================================================================
*/

/*
**************************************************************************
*  Mnemonic:	SIterm
*  Abstract:	Manage the transport provider block information relating to
*				the need to terminate the session. The block is left in the
*				list; it is unsafe to clean the lsit up outside of the SIwait
*				thread.  When safe, the SIrm_tpb() function can be called to
*				do the rest of the work that was originally done by SIterm.
*
*  Date:     	18 January 1995
*  Author:		E. Scott Daniels
*
**************************************************************************
*/
#include "sisetup.h"     //  get the setup stuff
#include "sitransport.h"


/*
	Abort the connection in such a way that there is no resulting time-wait state.
	This should be used cautiously but is needed for situations like when the Linux
	connect() system call manages to connect us to ourselves through the even number
	port bug.

	This needs a real file desc as there may not yet be a transport block when
	the connection may need to be aborted. For this reason, the function name is
	lower case indicating that user programmes are discouraged from using this
	function directly.
*/
extern void siabort_conn( int fd ) {
	struct linger	opt_val;		// value passed as option to set call

	opt_val.l_onoff = 1;			// MUST set linger on with a zero len timeout
	opt_val.l_linger = 0;

	setsockopt( fd, SOL_SOCKET, SO_LINGER, &opt_val, sizeof( opt_val ) );		// disable linger to prevent time-wait
	CLOSE( fd );			// close will now abort and not result in time-wait (do NOT use shutdown() first!)
}

/*
	Close the FD and mark the transport block as unusable/closed.
	Removal of the block from the list is safe only from the siwait
	thread.  If the abort flag is set in the transport block, then the
	connection is aborted (reset).
*/
extern void SIterm( struct ginfo_blk* gptr, struct tp_blk *tpptr ) {

	if( tpptr != NULL ) {
		if( tpptr->fd >= 0 ) {
			if( tpptr->flags & TPF_ABORT ) {
				siabort_conn( tpptr->fd );
			} else {
				CLOSE( tpptr->fd );
			}

			if( tpptr->fd < MAX_FDS ) {
				gptr->tp_map[tpptr->fd] = NULL;		// drop reference
			}
		}

		tpptr->fd = -1;								// prevent future sends etc.
		tpptr->flags |= TPF_DELETE;					// signal block deletion needed when safe
	}
}

/*
	It is safe to remove the block from the list; if it was in the list
	in the first place.
*/
extern void SIrm_tpb( struct ginfo_blk *gptr, struct tp_blk *tpptr ) {

	if( tpptr != NULL ) {
		if( tpptr->prev != NULL || tpptr->next != NULL ) {	// in the list
			if( tpptr->prev != NULL ) {            //  remove from the list
				tpptr->prev->next = tpptr->next;    //  point previous at the next
			} else {
				gptr->tplist = tpptr->next;        //  this was head, make next new head
			}

			if( tpptr->next != NULL ) {
				tpptr->next->prev = tpptr->prev;  //  point next one back behind this one
			}
		}

		free( tpptr->addr );             //  release the address bufers
		free( tpptr->paddr );
		free( tpptr );                   //  and release the block
	}
}