/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Author: Venkata N. Padmanabhan (padmanab@cs.berkeley.edu)
 */

#ifndef _NETINET_TCP_SESSION_H_
#define _NETINET_TCP_SESSION_H_
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>

#include <net/if.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#include <netinet/tcp_debug.h>

#ifdef TCP_STATS
#include <netinet/tcp_stats.h>

extern       struct timeval time;
#endif

extern int tcprexmtthresh;

/* TRUE if TCP session is enabled for this connection */
#define SESSION(tp) ((tp)->t_xflags & TXF_SESSION_ENABLE)
/* TRUE if tcp_output() has been called from session_output() */
#define SESSION_OUTPUT(tp) ((tp)->t_xflags & TXF_SESSION_OUTPUT)
/* TRUE if session cwnd should be incremented each time a new conn is added */
#define SESSION_INCR_CWND(tp) ((tp)->t_xflags & TXF_SESSION_INCR_CWND)
/* all connections between a pair of hosts are in the same session */
#define CONN_IN_SESSION(tp,sp) \
((((sp)->inp_laddr.s_addr == (tp)->t_inpcb->inp_laddr.s_addr) && \
  ((sp)->inp_faddr.s_addr == (tp)->t_inpcb->inp_faddr.s_addr)) ? 1 : 0)
/* make it clear that tcp_output() has been called from session_output() */
#define TCP_OUTPUT(tp) { \
	(tp)->t_xflags |= TXF_SESSION_OUTPUT; \
	tcp_output((tp)); \
	(tp)->t_xflags &= ~TXF_SESSION_OUTPUT; \
}

/* tests for per-session flags */
/* 
 * TRUE if ack is not the next expected in sequence (such as a
 * dupack or a partial ack). In such a case, session_opencwnd()
 * is not called.
 */
#define SESSION_LOSS_SUSPECTED(sp) ((sp)->flags & SSF_LOSS_SUSPECTED)
/*
 * TRUE if multiple losses are detected in a loss window. In such cases,
 * ownd is not adjusted when an ack that doesn't acknowledge any new
 * data (e.g., a dupack) is received.
 */
#define SESSION_DONT_ADJUST_OWND(sp) ((sp)->flags & SSF_DONT_ADJUST_OWND)

/* tests for per-segment flags */
/* TRUE if partial new ack received for this segment */
#define SEG_PARTIALACK(seg) ((seg)->flags & SGF_PARTIALACK)
/* TRUE if this is a retransmission */
#define SEG_RXMITTED(seg)   ((seg)->flags & SGF_RXMITTED)
/* 
 * TRUE if there are at least a threshold number (by default 3) of dupacks/later 
 * acks for this segment 
 */
#define SEG_THRESH_DUPACK(seg) ((seg)->flags & SGF_THRESH_DUPACK)

/* compare timestamps */
#define TSTMP_GT(t1,t2) SEQ_GT(t1,t2)

/*
 * These macros check if a delayed ack is long overdue. The threshold
 * is set to 2*(1/PR_FASTHZ) seconds. However, in general is undesirable 
 * to make any assumptions about the extent to which an ack can get
 * delayed, so this macro is deprecated.
 */
#ifdef FINE_GRAINED_TSTAMP
/* we set delack threshold to 2*200ms = 400ms */
#define DELACK_THRESH_GEQ(t1,t2) \
     ((((u_long) ((t1)-(t2))) >= 2*EXACT_HZ/PR_FASTHZ) ? 1:0)
#else
#define DELACK_THRESH_GEQ(t1,t2) \
     ((((u_long) ((t1)-(t2))) >= 1) ? 1:0)
#endif

#define TIMEOUT 1
#define FAST_REXMT 2
	
struct tcpcb;

/*
 * The TCP session protocol control block. "tp" points to a tcpcb that
 * is used to store certain session-wide state variables (e.g., snd_cwnd,
 * srtt, etc.). "connlist" points to the list of connections in the session.
 * "seglist" points to the list of unacked segments belonging to connections
 * in the session.
 */
struct sessionpcb {
	u_short flags;
#define SSF_LOSS_SUSPECTED 0x0001
#define SSF_DONT_ADJUST_OWND 0x0002
	struct	in_addr inp_faddr;
	struct	in_addr inp_laddr;
	int     numconn;
	int     numseg;
	short   dupack_ok;
	long    ownd;
	long    ownd_correction;
	u_long  highest_echoed_ts;
	tcp_seq session_seqno;
	tcp_seq recover;
	u_long  max_bytes_snd;
	struct tcpcb *tp;
	struct tcpcb *curconn;
	LIST_HEAD(connlist,tcpcb) connlist;
	TAILQ_HEAD(seglist,segment)  seglist;
	LIST_ENTRY(sessionpcb) next_session;
};

/*
 * For each unacked segment in the session, this structure stores its
 * sequence number within its connection, session-wide sequence number,
 * send timestamp, number of dupacks/later acks, and a pointer to its
 * connections tcpcb. All the segments are linked together in a list
 * sorted by the order of transmission.
 */
struct segment {
	u_short flags;
#define SGF_PARTIALACK 0x0001
#define SGF_RXMITTED   0x0002
#define SGF_THRESH_DUPACK 0x0004
	tcp_seq startseq;
	tcp_seq endseq;
	tcp_seq session_seqno;
	u_long  ts;
	short   dupacks;    /* on same connection */
	short   later_acks; /* on other connections */
	struct tcpcb *tp;
	TAILQ_ENTRY(segment) nextseg;
};

/* list of all TCP sessions */
LIST_HEAD(session_list,sessionpcb) session_list;

/* TCP session functions */
void session_init __P(());
struct sessionpcb *
     session_newpcb __P((struct tcpcb *));
struct sessionpcb *
     session_addconn __P((struct tcpcb *));
void session_delconn __P((struct tcpcb *));
void session_opencwnd __P((struct sessionpcb *, int));
void session_closecwnd __P((struct sessionpcb *, int));
void session_adjust_ownd __P((struct sessionpcb *, u_long));
void session_xmit_timer __P((struct tcpcb *, short));
void session_xmit_timer_exact __P((struct tcpcb *, u_long));
struct segment *
     session_rexmt_oneseg __P((struct sessionpcb *, struct segment *));
void session_rexmt __P((struct sessionpcb *));
void session_clean_segs __P((struct sessionpcb *, struct tcpcb *,
			     struct tcpiphdr *, struct tcp_opt_info *, int));
void session_timeout __P((struct sessionpcb *));
struct segment *
     session_output_oneseg __P((struct sessionpcb *, struct tcpcb *, int));
void session_output __P((struct sessionpcb *));
void session_input __P((struct tcpcb *, struct tcpiphdr *, 
			struct tcp_opt_info *, int));
void session_rcvd_syn_ack __P((struct tcpcb *, struct tcpiphdr *));

#endif /* _NETINET_TCP_SESSION_H_ */