#ifndef	_TCP_H
#define	_TCP_H

/* TCP implementation. Follows RFC 793 as closely as possible */
#ifndef	_GLOBAL_H
#include "global.h"
#endif

#ifndef	_MBUF_H
#include "mbuf.h"
#endif

#ifndef	_IFACE_H
#include "iface.h"
#endif

#ifndef	_INTERNET_H
#include "internet.h"
#endif

#ifndef _IP_H
#include "ip.h"
#endif

#ifndef	_NETUSER_H
#include "netuser.h"
#endif

#ifndef	_TIMER_H
#include "timer.h"
#endif

#define	DEF_MSS	512	/* Default maximum segment size */
#define	DEF_WND	2048	/* Default receiver window */
#define	RTTCACHE 16	/* # of TCP round-trip-time cache entries */
#define	DEF_RTT	5000	/* Initial guess at round trip time (5 sec) */
#define	MSL2	30	/* Guess at two maximum-segment lifetimes */
#define	MIN_RTO	500L	/* Minimum timeout, milliseconds */

#define	geniss()	((int32)msclock() << 12) /* Increment clock at 4 MB/sec */

/* Number of consecutive duplicate acks to trigger fast recovery */
#define	TCPDUPACKS	3

/* Round trip timing parameters */
#define	AGAIN	8	/* Average RTT gain = 1/8 */
#define	LAGAIN	3	/* Log2(AGAIN) */
#define	DGAIN	4	/* Mean deviation gain = 1/4 */
#define	LDGAIN	2	/* log2(DGAIN) */

/* TCP segment header -- internal representation
 * Note that this structure is NOT the actual header as it appears on the
 * network (in particular, the offset field is missing).
 * All that knowledge is in the functions ntohtcp() and htontcp() in tcpsubr.c
 */
#define TCPLEN		20	/* Minimum Header length, bytes */
#define	TCP_MAXOPT	40	/* Largest option field, bytes */
struct tcp {
	int16 source;	/* Source port */
	int16 dest;	/* Destination port */
	int32 seq;	/* Sequence number */
	int32 ack;	/* Acknowledgment number */
	int16 wnd;			/* Receiver flow control window */
	int16 checksum;			/* Checksum */
	int16 up;			/* Urgent pointer */
	int16 mss;			/* Optional max seg size */
	struct {
		char congest;	/* Echoed IP congestion experienced bit */
		char urg;
		char ack;
		char psh;
		char rst;
		char syn;
		char fin;
	} flags;
	char optlen;			/* Length of options field, bytes */
	char options[TCP_MAXOPT];	/* Options field */
};
/* TCP options */
#define	EOL_KIND	0
#define	NOOP_KIND	1
#define	MSS_KIND	2
#define	MSS_LENGTH	4

/* Resequencing queue entry */
struct reseq {
	struct reseq *next;	/* Linked-list pointer */
	struct tcp seg;		/* TCP header */
	struct mbuf *bp;	/* data */
	int16 length;		/* data length */
	char tos;		/* Type of service */
};
#define	NULLRESEQ	(struct reseq *)0

/* TCP connection control block */
struct tcb {
	struct tcb *next;	/* Linked list pointer */

	struct connection conn;

	char state;	/* Connection state */

/* These numbers match those defined in the MIB for TCP connection state */
#define	TCP_CLOSED		1
#define	TCP_LISTEN		2
#define	TCP_SYN_SENT		3
#define	TCP_SYN_RECEIVED	4
#define	TCP_ESTABLISHED		5
#define	TCP_FINWAIT1		6
#define	TCP_FINWAIT2		7
#define	TCP_CLOSE_WAIT		8
#define	TCP_LAST_ACK		9
#define	TCP_CLOSING		10
#define	TCP_TIME_WAIT		11

	char reason;		/* Reason for closing */
#define	NORMAL		0	/* Normal close */
#define	RESET		1	/* Reset by other end */
#define	TIMEOUT		2	/* Excessive retransmissions */
#define	NETWORK		3	/* Network problem (ICMP message) */

/* If reason == NETWORK, the ICMP type and code values are stored here */
	char type;
	char code;

	/* Send sequence variables */
	struct {
		int32 una;	/* First unacknowledged sequence number */
		int32 nxt;	/* Next sequence num to be sent for the first time */
		int32 ptr;	/* Working transmission pointer */
		int32 wl1;	/* Sequence number used for last window update */
		int32 wl2;	/* Ack number used for last window update */
		int16 wnd;	/* Other end's offered receive window */
		int16 up;	/* Send urgent pointer */
	} snd;
	int32 iss;		/* Initial send sequence number */
	int32 resent;		/* Count of bytes retransmitted */
	int16 cwind;		/* Congestion window */
	int16 ssthresh;		/* Slow-start threshold */
	int dupacks;		/* Count of duplicate (do-nothing) ACKs */

	/* Receive sequence variables */
	struct {
		int32 nxt;	/* Incoming sequence number expected next */
		int16 wnd;	/* Our offered receive window */
		int16 up;	/* Receive urgent pointer */
	} rcv;
	int32 irs;		/* Initial receive sequence number */
	int32 rerecv;		/* Count of duplicate bytes received */
	int16 mss;		/* Maximum segment size */

	int16 window;		/* Receiver window and send queue limit */
	int16 limit;		/* Send queue limit */

	void (*r_upcall) __ARGS((struct tcb *tcb,int cnt));
		/* Call when "significant" amount of data arrives */
	void (*t_upcall) __ARGS((struct tcb *tcb,int cnt));
		/* Call when ok to send more data */
	void (*s_upcall) __ARGS((struct tcb *tcb,int old,int new));
		/* Call when connection state changes */
	struct {		/* Control flags */
		char force;	/* We owe the other end an ACK or window update */
		char clone;	/* Server-type TCB, cloned on incoming SYN */
		char retran;	/* A retransmission has occurred */
		char active;	/* TCB created with an active open */
		char synack;	/* Our SYN has been acked */
		char rtt_run;	/* We're timing a segment */
		char congest;	/* Copy of last IP congest bit received */
	} flags;
	char tos;		/* Type of service (for IP) */
	int backoff;		/* Backoff interval */

	struct mbuf *rcvq;	/* Receive queue */
	struct mbuf *sndq;	/* Send queue */
	int16 rcvcnt;		/* Count of items on rcvq */
	int16 sndcnt;		/* Number of unacknowledged sequence numbers on
				 * sndq. NB: includes SYN and FIN, which don't
				 * actually appear on sndq!
				 */

	struct reseq *reseq;	/* Out-of-order segment queue */
	struct timer timer;	/* Retransmission timer */
	int32 rtt_time;		/* Stored clock values for RTT */
	int32 rttseq;		/* Sequence number being timed */
	int32 srtt;		/* Smoothed round trip time, milliseconds */
	int32 mdev;		/* Mean deviation, milliseconds */
	int32 lastactive;	/* Clock time when xmtr last active */

	int user;		/* User parameter (e.g., for mapping to an
				 * application control block
				 */
};
#define	NULLTCB	(struct tcb *)0
/* TCP round-trip time cache */
struct tcp_rtt {
	int32 addr;		/* Destination IP address */
	int32 srtt;		/* Most recent SRTT */
	int32 mdev;		/* Most recent mean deviation */
};
#define	NULLRTT	(struct tcp_rtt *)0
extern struct tcp_rtt Tcp_rtt[];

/* TCP statistics counters */
struct tcp_stat {
	int16 runt;		/* Smaller than minimum size */
	int16 checksum;		/* TCP header checksum errors */
	int16 conout;		/* Outgoing connection attempts */
	int16 conin;		/* Incoming connection attempts */
	int16 resets;		/* Resets generated */
	int16 bdcsts;		/* Bogus broadcast packets */
};
extern struct mib_entry Tcp_mib[];
#define	tcpRtoAlgorithm	Tcp_mib[1].value.integer
#define	tcpRtoMin	Tcp_mib[2].value.integer
#define	tcpRtoMax	Tcp_mib[3].value.integer
#define	tcpMaxConn	Tcp_mib[4].value.integer
#define	tcpActiveOpens	Tcp_mib[5].value.integer
#define tcpPassiveOpens	Tcp_mib[6].value.integer
#define	tcpAttemptFails	Tcp_mib[7].value.integer
#define	tcpEstabResets	Tcp_mib[8].value.integer
#define	tcpCurrEstab	Tcp_mib[9].value.integer
#define	tcpInSegs	Tcp_mib[10].value.integer
#define	tcpOutSegs	Tcp_mib[11].value.integer
#define	tcpRetransSegs	Tcp_mib[12].value.integer
#define	tcpInErrs	Tcp_mib[14].value.integer
#define	tcpOutRsts	Tcp_mib[15].value.integer
#define	NUMTCPMIB	15

extern struct tcb *Tcbs;
extern char *Tcpstates[];
extern char *Tcpreasons[];

/* In tcpcmd.c: */
extern int32 Tcp_irtt;
extern int16 Tcp_limit;
extern int16 Tcp_mss;
extern int Tcp_syndata;
extern int Tcp_trace;
extern int16 Tcp_window;

void st_tcp __ARGS((struct tcb *tcb));

/* In tcphdr.c: */
struct mbuf *htontcp __ARGS((struct tcp *tcph,struct mbuf *data,
	struct pseudo_header *ph));
int ntohtcp __ARGS((struct tcp *tcph,struct mbuf **bpp));

/* In tcpin.c: */
void reset __ARGS((struct ip *ip,struct tcp *seg));
void send_syn __ARGS((struct tcb *tcb));
void tcp_input __ARGS((struct iface *iface,struct ip *ip,struct mbuf *bp,
	int rxbroadcast));
void tcp_icmp __ARGS((int32 icsource,int32 source,int32 dest,
	char type,char code,struct mbuf **bpp));

/* In tcpsubr.c: */
void close_self __ARGS((struct tcb *tcb,int reason));
struct tcb *create_tcb __ARGS((struct connection *conn));
struct tcb *lookup_tcb __ARGS((struct connection *conn));
void rtt_add __ARGS((int32 addr,int32 rtt));
struct tcp_rtt *rtt_get __ARGS((int32 addr));
int seq_ge __ARGS((int32 x,int32 y));
int seq_gt __ARGS((int32 x,int32 y));
int seq_le __ARGS((int32 x,int32 y));
int seq_lt __ARGS((int32 x,int32 y));
int seq_within __ARGS((int32 x,int32 low,int32 high));
void setstate __ARGS((struct tcb *tcb,int newstate));
void tcp_garbage __ARGS((int red));

/* In tcpout.c: */
void tcp_output __ARGS((struct tcb *tcb));

/* In tcptimer.c: */
int32 backoff __ARGS((int n));
void tcp_timeout __ARGS((void *p));

/* In tcpuser.c: */
int close_tcp __ARGS((struct tcb *tcb));
int del_tcp __ARGS((struct tcb *tcb));
int kick __ARGS((int32 addr));
int kick_tcp __ARGS((struct tcb *tcb));
struct tcb *open_tcp __ARGS((struct socket *lsocket,struct socket *fsocket,
	int mode,int16 window,
	void (*r_upcall) __ARGS((struct tcb *tcb,int cnt)),
	void (*t_upcall) __ARGS((struct tcb *tcb,int cnt)),
	void (*s_upcall) __ARGS((struct tcb *tcb,int old,int new)),
	int tos,int user));
int recv_tcp __ARGS((struct tcb *tcb,struct mbuf **bpp,int16 cnt));
void reset_all __ARGS((void));
void reset_tcp __ARGS((struct tcb *tcb));
int send_tcp __ARGS((struct tcb *tcb,struct mbuf *bp));
char *tcp_port __ARGS((int16 n));
int tcpval __ARGS((struct tcb *tcb));

#endif	/* _TCP_H */
