/* tcp_usrreq.c 1.1 81/10/14 */
#include "../h/param.h"
#include "../bbnnet/net.h"
#include "../bbnnet/tcp.h"
#include "../bbnnet/ip.h"
#include "../bbnnet/imp.h"
#include "../bbnnet/ucb.h"
#include "../bbnnet/fsm.h"
#include "../bbnnet/tcp_pred.h"

lis_cls(wp)             /* passive open (1) */
struct work *wp;
{
	
COUNT(LIS_CLS);
	t_open(wp->w_tcb, PASSIVE);

	return(LISTEN);
}

sys_cls(wp)             /* active open (6) */
register struct work *wp;
{

COUNT(SYS_CLS);
	t_open(wp->w_tcb, ACTIVE);
	send_ctl(wp->w_tcb);            /* send SYN */

	return(SYN_SENT);
}

cls_opn(wp)             /* close request before receiving foreign SYN (10) */
struct work *wp;                           
{

COUNT(CLS_OPN);
	t_close(wp->w_tcb, UCLOSED);

	return(CLOSED);
}

cl2_clw(wp)             /* close request after receiving foreign FIN (13) */
struct work *wp;
{
	register struct tcb *tp;

COUNT(CL2_CLW);
	tp = wp->w_tcb;

	tp->snd_fin = TRUE;             /* send our own FIN */
	send_ctl(tp);                   
	tp->usr_closed = TRUE;

	return(CLOSING2);
}

cls_rwt(wp)             /* rcv request after foreign close (20) */
struct work *wp;
{
	register struct tcb *tp;

COUNT(CLS_RWT);
	tp = wp->w_tcb;

	present_data(tp);       /* present any remaining data */

	if (rcv_empty(tp)) {
        	t_close(tp, UCLOSED);
         	return(CLOSED);
	} else
		return(RCV_WAIT);

}

fw1_syr(wp)             /* close request on synced connection (24,25) */
struct work *wp;
{
	register struct tcb *tp;

COUNT(FW1_SYR);
	tp = wp->w_tcb;

	tp->snd_fin = TRUE;                     /* send FIN */
	send_ctl(tp);
	tp->usr_closed = TRUE;

	return(FIN_W1);
}

sss_syn(wp)             /* incoming seq on open connection (39) */
struct work *wp;
{
	register struct tcb *tp;

COUNT(SSS_SYN);
	tp = wp->w_tcb;

	rcv_data(tp, wp->w_dat);
	present_data(tp);

	return(SAME);
}

sss_snd(wp)             /* send request on open connection (40,41) */
struct work *wp;
{
	register struct tcb *tp;
	register struct mbuf *m, *n;
	register struct ucb *up;
	register off;
	sequence last;

COUNT(SSS_SND);
	tp = wp->w_tcb;
	up = tp->t_ucb;

	last = tp->snd_off;

	/* count number of mbufs in send data */

	for (m = n = (struct mbuf *)wp->w_dat; m != NULL; m = m->m_next) {
		up->uc_ssize++;
		last += m->m_len;
	}

	/* find end of send buffer and append data */

	if ((m = up->uc_sbuf) != NULL) {        /* something in send buffer */
		while (m->m_next != NULL) {             /* find the end */
			m = m->m_next;
			last += m->m_len;
		}
		last += m->m_len;

		/* if there's room in old buffer for new data, consolidate */

		off = m->m_off + m->m_len;
		while (n != NULL && (MSIZE - off) >= n->m_len) {
			bcopy((caddr_t)((int)n + n->m_off), 
			      (caddr_t)((int)m + off), n->m_len);
			m->m_len += n->m_len;
			off += n->m_len;
			up->uc_ssize--;
			n = m_free(n);
		}
		m->m_next = n;

	} else                                  /* nothing in send buffer */
		up->uc_sbuf = n;

	if (up->uc_flags & UEOL) {               /* set EOL */
		tp->snd_end = last;
	}

	if (up->uc_flags & UURG) {              /* urgent data */
		tp->snd_urp = last+1;
		tp->snd_urg = TRUE;
	} 

	send(tp);

	return(SAME);
}

sss_rcv(wp)             /* rcv request on open connection (42) */
struct work *wp;
{
	register struct tcb *tp;

COUNT(SSS_RCV);
	tp = wp->w_tcb;

	send_ctl(tp);                   /* send new window */
	present_data(tp);

	return(SAME);
}

cls_nsy(wp)                  /* abort request on unsynced connection (44) */
struct work *wp;
{

COUNT(CLS_NSY);
	t_close(wp->w_tcb, UABORT);

	return(CLOSED);
}

cls_syn(wp)             /* abort request on synced connection (45) */
struct work *wp;
{
	register struct tcb *tp;

COUNT(CLS_SYN);
	tp = wp->w_tcb;

	tp->snd_rst = TRUE;            /* send reset */
	send_null(tp);
	t_close(tp, UABORT);

	return(CLOSED);
}

cls_act(wp)             /* net closing open connection (47) */
struct work *wp;
{

COUNT(CLS_ACT);
	t_close(wp->w_tcb, UNETDWN);

	return(CLOSED);
}

cls_err(wp)             /* invalid user request in closing states */
struct work *wp;
{
COUNT(CLS_ERR);
	to_user(wp->w_tcb->t_ucb, UCLSERR);

	return(SAME);
}

lis_netr(wp)             /* incoming seg in LISTEN (3,4) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(LIS_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	if (!syn_ok(tp, n))             /* must have good SYN */
		return(EFAILEC);

	/* fill in unspecified foreign host address.  get/create entry
	   in foreign host table.  if none available, ignore.  probably
	   should send reset here. */

	if ((tp->t_ucb->uc_host = h_make(&n->t_s)) == NULL)
		return(EFAILEC);

	tp->t_fport = n->t_src;

	rcv_data(tp, n);

	if (!tp->fin_rcvd) {            /* no FIN (4) */

		/* start init timer now that we have foreign host */

		tp->t_init = T_INIT/2;
		return(L_SYN_RCVD);

	} else {                        /* got a FIN, start timer (3) */
        	tp->t_finack = T_2ML;
        	tp->waited_2_ml = FALSE;
		return(CLOSE_WAIT);
	}
}

sys_netr(wp)            /* incoming segment after SYN sent (8,9,11,32) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(SYS_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	if (!syn_ok(tp, n))             /* must have good SYN */
		return(EFAILEC);

	rcv_data(tp, n);

	if (tp->fin_rcvd) {             /* got a FIN */

		/* if good ACK, present any data */

		if (n->t_ack) {

			if (n->t_ackno > tp->iss)       /* 32 */
				present_data(tp);

		} else {                                /* 9 */
                	tp->t_finack = T_2ML;
                	tp->waited_2_ml = FALSE;
		}
		return (CLOSE_WAIT);

	} else                          /* no FIN */

		/* if good ACK, open connection, otherwise wait for one */

		if (n->t_ack) {                         /* 11 */
			present_data(tp);
			return(ESTAB);
		} else
			return(SYN_RCVD);               /* 8 */
}

cl1_netr(wp)            /* incoming seg after we closed (15,18,22,23,30,39) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(CL1_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	if (ack_fin(tp, n))                     /* got ACK of our FIN */

        	if (n->t_fin) {                 /* got for FIN (23) */
        
        		rcv_ctl(tp, n);
                	tp->t_finack = T_2ML;
                	tp->waited_2_ml = FALSE;
                        return(TIME_WAIT);
        	} else {

			/* if wait done, see if any data left for user */

        		if (tp->waited_2_ml)
        
        			if (rcv_empty(tp)) {    /* 15 */
        
        				t_close(tp, UCLOSED);
        				return(CLOSED);
        			} else
        				return(RCV_WAIT);       /* 18 */
        
        		else
        			return(TIME_WAIT);      /* 22 */
		}

	else                            /* our FIN not ACKed yet */

		if (n->t_fin) {                 /* rcvd for FIN (30) */

			rcv_ctl(tp, n);
                	tp->t_finack = T_2ML;
                	tp->waited_2_ml = FALSE;

		} else {                        /* no FIN, just proc new data (39) */

        		rcv_data(tp, n);
        		present_data(tp);
		}

	return(SAME);
}

cl2_netr(wp)            /* incoming seg after foreign close (16,19,31,39) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(CL2_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	if (ack_fin(tp, n)) {                   /* this is ACK of our fin */

		/* if no data left for user, close; otherwise wait */

		if (rcv_empty(tp)) {                            /* 16 */
			 
			t_close(tp, UCLOSED);
			return(CLOSED);
		} else                                          /* 19 */
			return(RCV_WAIT);

	} else                                  /* no ACK of our FIN */

		/* duplicate FIN or data */

		if (n->t_fin)                                   /* 31 */
			send_ctl(tp);           /* ACK duplicate FIN */

		else {                                          /* 39 */
			rcv_data(tp, n);                         
			present_data(tp);
		}

	return(SAME);
}

fw1_netr(wp)            /* incoming seg after user close (26,27,28,39) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(FW1_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	/* process any incoming data, since we closed but they didn't */

	rcv_data(tp, n);
	present_data(tp);

	if (ack_fin(tp, n))                     /* our FIN got ACKed */

		if (tp->fin_rcvd) {                     /* got for FIN (28) */
                	tp->t_finack = T_2ML;
                	tp->waited_2_ml = FALSE;
			return(TIME_WAIT);
		} else                                  /* no FIN, wait (27) */
			return(FIN_W2);

	else                                    /* no ACK of FIN */

		if (tp->fin_rcvd) {                     /* got for FIN (26) */
                	tp->t_finack = T_2ML;
                	tp->waited_2_ml = FALSE;
			return(CLOSING1);
                } 

	return(SAME);                                   /* 39 */
}

syr_netr(wp)             /* incoming seg after SYN rcvd (5,33) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(SYR_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	if (!n->t_ack || (n->t_ack && n->t_ackno <= tp->iss))  /* must have ACK of our SYN */
		return(EFAILEC);

	rcv_data(tp, n);
	present_data(tp);

	/* if no FIN, open connection, otherwise wait for user close */

	if (tp->fin_rcvd)                               /* 33 */
		return(CLOSE_WAIT);
	else                                            /* 5 */
		return(ESTAB);

}

est_netr(wp)            /* incoming seg on open connection (12,39) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(EST_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	rcv_data(tp, n);
	present_data(tp);

	/* if no FIN, remain open, otherwise wait for user close */

	if (tp->fin_rcvd)                       /* 12 */
		return(CLOSE_WAIT);
	else                                    /* 39 */
        	return(SAME);
}

fw2_netr(wp)            /* incoming seg while waiting for for FIN (12,39) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(FW2_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	/* process data since we closed, but they may not have */

	rcv_data(tp, n);
	present_data(tp);

	/* if we get the FIN, start the finack timer, else keep waiting */

	if (tp->fin_rcvd) {                     /* got for FIN (29) */
		tp->t_finack = T_2ML;
		tp->waited_2_ml = FALSE;
		return(TIME_WAIT);
	} else                                  /* 39 */
        	return(SAME);
}

cwt_netr(wp)            /* incoming seg after exchange of FINs (30,31,39) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(CWT_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	/* either duplicate FIN or data */

	if (n->t_fin) {

		if (n->t_ack && n->t_ackno <= tp->seq_fin) {    /* dup ACK (30) */

                	rcv_ctl(tp, n);
                	tp->t_finack = T_2ML;
                	tp->waited_2_ml = FALSE;
		} else                                          /* 31 */
			send_ctl(tp);

	} else {                /* duplicate data (39) */

		rcv_data(tp, n);
		present_data(tp);
	}

	return(SAME);
}

rwt_netr(wp)            /* incoming seg while waiting for user rcv (30,21) */
struct work *wp;
{
	register struct tcb *tp;
	register struct th *n;

COUNT(RWT_NETR);
	tp = wp->w_tcb;
	n = (struct th *)wp->w_dat;

	/* handle duplicate ACK of our FIN */

	if (n->t_fin && n->t_ack && n->t_ackno <= tp->seq_fin) {    /* 30 */

        	rcv_ctl(tp, n);
        	tp->t_finack = T_2ML;
        	tp->waited_2_ml = FALSE;
	} 

	return(SAME);
}

timers(wp)              /* timer processor (14,17,34,35,36,37,38) */
struct work *wp;
{
	register struct tcb *tp;
	register type;

COUNT(TIMERS);
	tp = wp->w_tcb;
	type = wp->w_stype;

	switch (type) {

	case TINIT:             /* initialization timer */

		if (!tp->syn_acked) {           /* haven't got ACK of our SYN (35) */

			t_close(tp, UINTIMO);
			return(CLOSED);
		}
		break;

	case TFINACK:           /* fin-ack timer */   

		if (tp->t_state == TIME_WAIT) {

			/* can be sure our ACK of for FIN was rcvd,
			   can close if no data left for user */

			if (rcv_empty(tp)) {            /* 14 */
				t_close(tp, UCLOSED);
				return(CLOSED);
			} else                          /* 17 */
				return(RCV_WAIT);

		} else if (tp->t_state == CLOSING1)     /* 37 */

			/* safe to close */

			tp->waited_2_ml = TRUE;

	        break;

	case TREXMT:            /* retransmission timer */

		/* set up for a retransmission, increase rexmt time
		   in case of multiple retransmissions. */

	        if (tp->t_rexmt_val > tp->snd_una) {   /* 34 */
	        	tp->snd_nxt = tp->snd_una;
	        	tp->rexmt = TRUE;
			tp->t_xmtime = tp->t_xmtime << 1;                  
        		if (tp->t_xmtime > T_REMAX)
        			tp->t_xmtime = T_REMAX;
	        	send(tp);
	        }
		break;

	case TREXMTTL:          /* retransmit too long */

		/* tell user */

        	if (tp->t_rtl_val > tp->snd_una)        /* 36 */
        		to_user(tp->t_ucb, URXTIMO);

		/* if user has already closed, abort the connection */

		if (tp->usr_closed) {
			t_close(tp, URXTIMO);
			return(CLOSED);
		}
		break;

	case TPERSIST:          /* persist timer */

		/* force a byte send through closed window */

        	tp->force_one = TRUE;                   /* 38 */
        	send(tp);
		break;
	}

	return(SAME);
}

netprepr(tp, n)         /* network preproc (66,67,68,69,70,71,72,73,74,75,76) */
register struct tcb *tp;
register struct th *n;
{

COUNT(NETPREPR);
	switch (tp->t_state) {

	case LISTEN:

		if (n->t_ack || !syn_ok(tp, n))
			send_rst(tp, n);
		else if (!n->t_rst)
			return(0);
		break;

	case SYN_SENT:

		if (!ack_ok(tp, n) || !syn_ok(tp, n))

			send_rst(tp, n);        /* 71,72,75 */

		else if (n->t_rst) {

			t_close(tp, URESET);            /* 70 */
			return(CLOSED);
		} else
			return(0);
		break;

	default:

        	if (n->t_rst) {         /* any resets? */
        
        		if (n->t_seq >= tp->rcv_nxt) {  /* good reset */
        
        			if (tp->t_state == L_SYN_RCVD) {

        				if (ack_ok(tp, n)) {    /* 67 */
						t_cancel(tp, TREXMT);
						t_cancel(tp, TREXMTTL);
						t_cancel(tp, TPERSIST);
						h_free(tp->t_ucb->uc_host);
        					return(LISTEN);
					}
        			} else {                        /* 66 */
                        		t_close(tp, URESET);
                			return(CLOSED);
        			}
        		}                               /* else 69 */
        		break;
        	}

	case SYN_RCVD:

		if (ack_ok(tp, n))              /* acceptable ack */

			if (syn_ok(tp, n) && n->t_seq != tp->irs)      

				/* bad syn (73,75,76) */

				send_null(tp);  
			else
				return(0);      /* acceptable segment */
		else
			send_rst(tp, n);        /* bad ack (74) */

	}

	return(-1);     /* tell caller to eat segment (unacceptable) */
}