/*
 * Active Router Transport Protocol (ARTP) implementation
 * Copyright (c) 2004, Tomas Rebok
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the "BSD License" which is
 * distributed with the software in the file LICENSE.
 *
 * This program 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 BSD
 * License for more details.
 */

/** @file
 * @c ARTP structures for storing session information.
 * @author Tomas Rebok
 * @date 2004
 */
 

#ifndef ARTP_STRUCTS_H
#define ARTP_STRUCTS_H   1


#include <sys/socket.h>
#include <sys/types.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <pthread.h>
#include "types.h"
#include "net.h"
#include "options.h"


/** Enumeration of available session status states.
 */
enum Tsession_status { 
	/** connection lives */ LIVE, 
	/** connection lost  */ DEAD 
};


/** Enumeration of available session types */
enum Tsession_type { 
	/** non-established session */ NON_EST, 
	/** established session     */ EST 
};


/** Structure for undeliverable sessions.
 * This structure is used to store sessions whose initial packets cannot be
 * delivered.
 */
struct dead_zero_sessions
{
	/** session identification number */
    SID_TYPE sid; 

	/** session's receiver */
	union artp_receiver receiver;

	/** slipper sign */
	int invalid;

	/** next item in this structure */
	struct dead_zero_sessions *next;
};


/** Structure for storing session information.
 */
struct session_item
{
	/** session identification number */
    SID_TYPE session_sid;

	/** session's receiver */
	union artp_receiver session_receiver;

	/** next packet sequence number */
	SEQ_TYPE current_seq;

	/** the identification number of session buffers */
	int buffers_id;

	/** session status */
	enum Tsession_status session_status;

	/** session type */
	enum Tsession_type session_type;
	
	/** options which this session sends */
	void *options[OPTIONS_COUNT];

	/** options which this session receives */
	void *partner_options[OPTIONS_COUNT];

	/** session congestion window size */
	unsigned long int cwnd;
	
	/** the size of unacknowledged packets for this session */
	unsigned long int flight;

	/** current maximal segment size */
	MSS_TYPE mss;

	/** current maximal acks count */
	unsigned int max_acks_count;
	
	/** current maximal send buffer size */
	unsigned long int sbuffer_max_size;
	
	/** current maximal receive buffer size */
	unsigned long int rbuffer_max_size;
	
	/** current R.E.D. limit */
	unsigned long int rbuffer_red_limit;
	
	/** current R.E.D. dropping probability */
	int rbuffer_red_prob;
	
	/** current session round trip time */
	double rtt;

	/** current sessin smooth round trip time */
	double srtt;

	/** current retransmit timeout */
	double rto;

	/** current difference between session's time and its partner's time */
	double ts_delta;

	/** maximal retries timeout for session */
	RETR_TIMEOUT_TYPE retries_timeout;

	/** packets expiration time that belong to this session */
	TS_TYPE expiration_time;

	/** last link activity time */
	double last_send_time;

	/** session reference counter */
	unsigned int ref_counter;

	/** mutex used for mutual exclusion of threads changing reference counter */
	pthread_mutex_t ref_counter_mutex;

	/** mutex used for mutual exclusion of threads changing some session 
	 * critical parameters.
	 */
	pthread_mutex_t session_mutex;
};


#endif

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