/*
 * Copyright (c) 1984, 1985, 1986 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 *
 *	@(#)spp_usrreq.c	7.1 (Berkeley) 6/5/86
 */

#include "param.h"
#include "dir.h"
#include "user.h"
#include "mbuf.h"
#include "protosw.h"
#include "socket.h"
#include "socketvar.h"
#include "errno.h"

#include "../net/if.h"
#include "../net/route.h"
#include "../netinet/tcp_fsm.h"
#include "../netinet/tcp_timer.h"

#include "ns.h"
#include "ns_pcb.h"
#include "idp.h"
#include "idp_var.h"
#include "ns_error.h"
#include "sp.h"
#include "spidp.h"
#include "spp_var.h"
#include "spp_debug.h"

/*
 * SP protocol implementation.
 */
spp_init()
{

	spp_iss = 1; /* WRONG !! should fish it out of TODR */
}
struct spidp spp_savesi;
int traceallspps = 0;
extern int sppconsdebug;
int spp_hardnosed;
int spp_use_delack = 0;

/*ARGSUSED*/
spp_input(m, nsp, ifp)
	register struct mbuf *m;
	register struct nspcb *nsp;
	struct ifnet *ifp;
{
	register struct sppcb *cb;
	register struct spidp *si = mtod(m, struct spidp *);
	register struct socket *so;
	short ostate;
	int dropsocket = 0;


	if (nsp == 0) {
		panic("No nspcb in spp_input\n");
		return;
	}

	cb = nstosppcb(nsp);
	if (cb == 0) goto bad;

	if (m->m_len < sizeof(*si)) {
		if ((m = m_pullup(m, sizeof(*si))) == 0) {
			spp_istat.hdrops++;
			return;
		}
		si = mtod(m, struct spidp *);
	}
	si->si_seq = ntohs(si->si_seq);
	si->si_ack = ntohs(si->si_ack);
	si->si_alo = ntohs(si->si_alo);

	so = nsp->nsp_socket;
	if (so->so_options & SO_DEBUG || traceallspps) {
		ostate = cb->s_state;
		spp_savesi = *si;
	}
	if (so->so_options & SO_ACCEPTCONN) {
		so = sonewconn(so);
		if (so == 0) {
			spp_istat.nonucn++;
			goto drop;
		}
		/*
		 * This is ugly, but ....
		 *
		 * Mark socket as temporary until we're
		 * committed to keeping it.  The code at
		 * ``drop'' and ``dropwithreset'' check the
		 * flag dropsocket to see if the temporary
		 * socket created here should be discarded.
		 * We mark the socket as discardable until
		 * we're committed to it below in TCPS_LISTEN.
		 */
		dropsocket++;
		nsp = (struct nspcb *)so->so_pcb;
		nsp->nsp_laddr = si->si_dna;
		cb = nstosppcb(nsp);
		cb->s_state = TCPS_LISTEN;
	}

	/*
	 * Packet received on connection.
	 * reset idle time and keep-alive timer;
	 */
	cb->s_idle = 0;
	cb->s_timer[TCPT_KEEP] = TCPTV_KEEP;

	switch (cb->s_state) {

	case TCPS_LISTEN:{
		struct mbuf *am;
		register struct sockaddr_ns *sns;
		struct ns_addr laddr;

		/*
		 * If somebody here was carying on a conversation
		 * and went away, and his pen pal thinks he can
		 * still talk, we get the misdirected packet.
		 */
		if (spp_hardnosed && (si->si_did != 0 || si->si_seq != 0)) {
			spp_istat.gonawy++;
			goto dropwithreset;
		}
		am = m_get(M_DONTWAIT, MT_SONAME);
		if (am == NULL)
			goto drop;
		am->m_len = sizeof (struct sockaddr_ns);
		sns = mtod(am, struct sockaddr_ns *);
		sns->sns_family = AF_NS;
		sns->sns_addr = si->si_sna;
		laddr = nsp->nsp_laddr;
		if (ns_nullhost(laddr))
			nsp->nsp_laddr = si->si_dna;
		if (ns_pcbconnect(nsp, am)) {
			nsp->nsp_laddr = laddr;
			(void) m_free(am);
			spp_istat.noconn++;
			goto drop;
		}
		(void) m_free(am);
		spp_template(cb);
		dropsocket = 0;		/* committed to socket */
		cb->s_did = si->si_sid;
		cb->s_rack = si->si_ack;
		cb->s_ralo = si->si_alo;
#define THREEWAYSHAKE
#ifdef THREEWAYSHAKE
		cb->s_state = TCPS_SYN_RECEIVED;
		cb->s_force = 1 + TCPT_REXMT;
		cb->s_timer[TCPT_REXMT] = 2 * TCPTV_MIN;
		}
		break;
	/*
	 * This state means that we have heard a response
	 * to our acceptance of their connection
	 * It is probably logically unnecessary in this
	 * implementation.
	 */
	 case TCPS_SYN_RECEIVED:
		if (si->si_did!=cb->s_sid) {
			spp_istat.wrncon++;
			goto drop;
		}
#endif
		nsp->nsp_fport =  si->si_sport;
		cb->s_timer[TCPT_REXMT] = 0;
		cb->s_timer[TCPT_KEEP] = TCPTV_KEEP;
		soisconnected(so);
		cb->s_state = TCPS_ESTABLISHED;
		break;

	/*
	 * This state means that we have gotten a response
	 * to our attempt to establish a connection.
	 * We fill in the data from the other side,
	 * telling us which port to respond to, instead of the well-
	 * known one we might have sent to in the first place.
	 * We also require that this is a response to our
	 * connection id.
	 */
	case TCPS_SYN_SENT:
		if (si->si_did!=cb->s_sid) {
			spp_istat.notme++;
			goto drop;
		}
		cb->s_did = si->si_sid;
		cb->s_rack = si->si_ack;
		cb->s_ralo = si->si_alo;
		cb->s_dport = nsp->nsp_fport =  si->si_sport;
		cb->s_timer[TCPT_REXMT] = 0;
		cb->s_flags |= SF_AK;
		soisconnected(so);
		cb->s_state = TCPS_ESTABLISHED;
	}
	if (so->so_options & SO_DEBUG || traceallspps)
		spp_trace(SA_INPUT, (u_char)ostate, cb, &spp_savesi, 0);

	m->m_len -= sizeof (struct idp);
	m->m_off += sizeof (struct idp);

	if (spp_reass(cb, si)) {
		m_freem(m);
	}
	(void) spp_output(cb, (struct mbuf *)0);
	return;

dropwithreset:
	if (dropsocket)
		(void) soabort(so);
	si->si_seq = ntohs(si->si_seq);
	si->si_ack = ntohs(si->si_ack);
	si->si_alo = ntohs(si->si_alo);
	ns_error(dtom(si), NS_ERR_NOSOCK, 0);
	if (cb->s_nspcb->nsp_socket->so_options & SO_DEBUG || traceallspps)
		spp_trace(SA_DROP, (u_char)ostate, cb, &spp_savesi, 0);
	return;

drop:
bad:
	if (cb == 0 || cb->s_nspcb->nsp_socket->so_options & SO_DEBUG || traceallspps)
		spp_trace(SA_DROP, (u_char)ostate, cb, &spp_savesi, 0);
	m_freem(m);
}

/*
 * This is structurally similar to the tcp reassembly routine
 * but its function is somewhat different:  It merely queues
 * packets up, and suppresses duplicates.
 */
spp_reass(cb, si)
register struct sppcb *cb;
register struct spidp *si;
{
	register struct spidp_q *q;
	register struct mbuf *m;
	struct socket *so = cb->s_nspcb->nsp_socket;
	struct sockbuf *sb = & (so->so_rcv);
	char packetp = cb->s_flags & SF_HI;
	char wakeup = 0;


	if (si == SI(0))
		goto present;
	/*
	 * Update our news from them.
	 */
	if (si->si_cc & SP_SA)
		cb->s_flags |= (spp_use_delack ? SF_DELACK : SF_AK);
	if (SSEQ_GT(si->si_ack, cb->s_rack)) {
		cb->s_rack = si->si_ack;
		/*
		 * If there are other packets outstanding,
		 * restart the timer for them.
		 */
		if (SSEQ_GEQ(cb->s_snt, si->si_ack)) {
			TCPT_RANGESET(cb->s_timer[TCPT_REXMT],
				tcp_beta * cb->s_srtt, TCPTV_MIN,
				TCPTV_MAX);
			cb->s_rxtshift = 0;
		} else
			cb->s_timer[TCPT_REXMT] = 0;
		/*
		 * If transmit timer is running and timed sequence
		 * number was acked, update smoothed round trip time.
		 */
		if (cb->s_rtt && SSEQ_GT(si->si_ack, cb->s_rtseq)) {
			if (cb->s_srtt == 0)
				cb->s_srtt = cb->s_rtt;
			else
				cb->s_srtt =
				    tcp_alpha * cb->s_srtt +
				    (1 - tcp_alpha) * cb->s_rtt;
			cb->s_rtt = 0;
		}
	}
	if (SSEQ_GT(si->si_alo, cb->s_ralo)) {
		cb->s_ralo = si->si_alo;
		cb->s_timer[TCPT_PERSIST] = 0;
	}
	/*
	 * If this is a system packet, we don't need to
	 * queue it up, and won't update acknowledge #
	 */
	if (si->si_cc & SP_SP) {
		m_freem(dtom(si));
		return (0);
	}

	/*
	 * If this packet number has a sequence number less
	 * than that of the first packet not yet seen coming
	 * from them, this must be a duplicate, so drop.
	 */
	if (SSEQ_LT(si->si_seq, cb->s_ack)) {
		spp_istat.bdreas++;
		if (si->si_seq == cb->s_ack-1)
			spp_istat.lstdup++;
		return (1);
	}
	/*
	 * If this packet number is higher than that which
	 * we have allocated refuse it, unless urgent
	 */
	if (SSEQ_GT(si->si_seq, cb->s_alo)) {
		if (si->si_cc & SP_OB) {
			if (SSEQ_GT(si->si_seq, cb->s_alo + 60)) {
				ns_error(dtom(si), NS_ERR_FULLUP, 0);
				return (0);
			} /* else queue this packet; */
		} else {
			spp_istat.notyet++;
			return (1);
		}
	}

	/*
	 * Loop through all packets queued up to insert in
	 * appropriate sequence.
	 */

	for (q = cb->s_q.si_next; q!=&cb->s_q; q = q->si_next) {
	    if (si->si_seq == SI(q)->si_seq) return (1); /*duplicate */
	    if (SSEQ_LT(si->si_seq, SI(q)->si_seq)) break;
	}
	insque(si, q->si_prev);
	/*
	 * If this packet is urgent, inform process
	 */
	if (si->si_cc & SP_OB) {
		cb->s_iobc = ((char *)si)[1 + sizeof(*si)];
		sohasoutofband(so);
		cb->s_oobflags |= SF_IOOB;
	}
present:
#define SPINC sizeof(struct sphdr)
	/*
	 * Loop through all packets queued up to update acknowledge
	 * number, and present all acknowledged data to user;
	 * If in packet interface mode, show packet headers.
	 */
	for (q = cb->s_q.si_next; q!=&cb->s_q; q = q->si_next) {
		  if (SI(q)->si_seq == cb->s_ack) {
			cb->s_ack++;
			m = dtom(q);
			if (SI(q)->si_cc & SP_OB) {
				cb->s_oobflags &= ~SF_IOOB;
				if (sb->sb_cc)
					so->so_oobmark = sb->sb_cc;
				else
					so->so_state |= SS_RCVATMARK;
			}
			q = q->si_prev;
			remque(q->si_next);
			wakeup = 1;
			if (packetp) {
				sbappendrecord(sb, m);
			} else {
				cb->s_rhdr = *mtod(m, struct sphdr *);
				m->m_off += SPINC;
				m->m_len -= SPINC;
				sbappend(sb, m);
			}
		  } else
			break;
	}
	if (wakeup) sorwakeup(so);
	return (0);
}

spp_ctlinput(cmd, arg)
	int cmd;
	caddr_t arg;
{
	struct ns_addr *na;
	extern u_char nsctlerrmap[];
	extern spp_abort();
	extern struct nspcb *idp_drop();
	struct ns_errp *errp;
	struct nspcb *nsp;
	struct sockaddr_ns *sns;
	int type;

	if (cmd < 0 || cmd > PRC_NCMDS)
		return;
	type = NS_ERR_UNREACH_HOST;

	switch (cmd) {

	case PRC_ROUTEDEAD:
	case PRC_QUENCH:
		break;

	case PRC_IFDOWN:
	case PRC_HOSTDEAD:
	case PRC_HOSTUNREACH:
		sns = (struct sockaddr_ns *)arg;
		if (sns->sns_family != AF_NS)
			return;
		na = &sns->sns_addr;
		break;

	default:
		errp = (struct ns_errp *)arg;
		na = &errp->ns_err_idp.idp_dna;
		type = errp->ns_err_num;
		type = ntohs((u_short)type);
	}
	switch (type) {

	case NS_ERR_UNREACH_HOST:
		ns_pcbnotify(na, (int)nsctlerrmap[cmd], spp_abort, (long) 0);
		break;

	case NS_ERR_TOO_BIG:
	case NS_ERR_NOSOCK:
		nsp = ns_pcblookup(na, errp->ns_err_idp.idp_sna.x_port,
			NS_WILDCARD);
		if (nsp) {
			if(nsp->nsp_pcb)
				(void) spp_drop((struct sppcb *)nsp->nsp_pcb,
						(int)nsctlerrmap[cmd]);
			else
				(void) idp_drop(nsp, (int)nsctlerrmap[cmd]);
		}
	}
}

#ifdef notdef
int
spp_fixmtu(nsp)
register struct nspcb *nsp;
{
	register struct sppcb *cb = (struct sppcb *)(nsp->nsp_pcb);
	register struct mbuf *m;
	register struct spidp *si;
	struct ns_errp *ep;
	struct sockbuf *sb;
	int badseq, len;
	struct mbuf *firstbad, *m0;

	if (cb) {
		/* 
		 * The notification that we have sent
		 * too much is bad news -- we will
		 * have to go through queued up so far
		 * splitting ones which are too big and
		 * reassigning sequence numbers and checksums.
		 * we should then retransmit all packets from
		 * one above the offending packet to the last one
		 * we had sent (or our allocation)
		 * then the offending one so that the any queued
		 * data at our destination will be discarded.
		 */
		 ep = (struct ns_errp *)nsp->nsp_notify_param;
		 sb = &nsp->nsp_socket->so_snd;
		 cb->s_mtu = ep->ns_err_param;
		 badseq = SI(&ep->ns_err_idp)->si_seq;
		 for (m = sb->sb_mb; m; m = m->m_act) {
			si = mtod(m, struct spidp *);
			if (si->si_seq == badseq)
				break;
		 }
		 if (m == 0) return;
		 firstbad = m;
		 /*for (;;) {*/
			/* calculate length */
			for (m0 = m, len = 0; m ; m = m->m_next)
				len += m->m_len;
			if (len > cb->s_mtu) {
			}
		/* FINISH THIS
		} */
	}
}
#endif

int spp_output_cnt = 0;

spp_output(cb, m0)
	register struct sppcb *cb;
	struct mbuf *m0;
{
	struct socket *so = cb->s_nspcb->nsp_socket;
	register struct mbuf *m;
	register struct spidp *si = (struct spidp *) 0;
	register struct sockbuf *sb = &(so->so_snd);
	register int len = 0;
	int error = 0;
	u_short lookfor = 0;
	struct mbuf *mprev;
	extern int idpcksum;

	if (m0) {
		int mtu = cb->s_mtu;
		int datalen;
		/*
		 * Make sure that packet isn't too big.
		 */
		for (m = m0; m ; m = m->m_next) {
			mprev = m;
			len += m->m_len;
		}
		datalen = (cb->s_flags & SF_HO) ?
				len - sizeof (struct sphdr) : len;
		if (datalen > mtu) {
			if (cb->s_flags & SF_PI) {
				m_freem(m0);
				return (EMSGSIZE);
			} else {
				int off = 0;
				int oldEM = cb->s_cc & SP_EM;

				cb->s_cc &= ~SP_EM;
				while (len > mtu) {
					m = m_copy(m0, off, mtu);
					if (m == NULL) {
						error = ENOBUFS;
						goto bad_copy;
					}
					error = spp_output(cb, m);
					if (error) {
					bad_copy:
						cb->s_cc |= oldEM;
						m_freem(m0);
						return(error);
					}
					m_adj(m0, mtu);
					len -= mtu;
				}
				cb->s_cc |= oldEM;
			}
		}
		/*
		 * Force length even, by adding a "garbage byte" if
		 * necessary.
		 */
		if (len & 1) {
			m = mprev;
			if (m->m_len + m->m_off < MMAXOFF)
				m->m_len++;
			else {
				struct mbuf *m1 = m_get(M_DONTWAIT, MT_DATA);

				if (m1 == 0) {
					m_freem(m0);
					return (ENOBUFS);
				}
				m1->m_len = 1;
				m1->m_off = MMAXOFF - 1;
				m->m_next = m1;
			}
		}
		m = m_get(M_DONTWAIT, MT_HEADER);
		if (m == 0) {
			m_freem(m0);
			return (ENOBUFS);
		}
		/*
		 * Fill in mbuf with extended SP header
		 * and addresses and length put into network format.
		 * Long align so prepended ip headers will work on Gould.
		 */
		m->m_off = MMAXOFF - sizeof (struct spidp) - 2;
		m->m_len = sizeof (struct spidp);
		m->m_next = m0;
		si = mtod(m, struct spidp *);
		*si = cb->s_shdr;
		if ((cb->s_flags & SF_PI) && (cb->s_flags & SF_HO)) {
			register struct sphdr *sh;
			if (m0->m_len < sizeof (*sh)) {
				if((m0 = m_pullup(m0, sizeof(*sh))) == NULL) {
					(void) m_free(m);
					m_freem(m0);
					return (EINVAL);
				}
				m->m_next = m0;
			}
			sh = mtod(m0, struct sphdr *);
			si->si_dt = sh->sp_dt;
			si->si_cc |= sh->sp_cc & SP_EM;
			m0->m_len -= sizeof (*sh);
			m0->m_off += sizeof (*sh);
			len -= sizeof (*sh);
		}
		len += sizeof(*si);
		if (cb->s_oobflags & SF_SOOB) {
			/*
			 * Per jqj@cornell:
			 * make sure OB packets convey exactly 1 byte.
			 * If the packet is 1 byte or larger, we
			 * have already guaranted there to be at least
			 * one garbage byte for the checksum, and
			 * extra bytes shouldn't hurt!
			 */
			if (len > sizeof(*si)) {
				si->si_cc |= SP_OB;
				len = (1 + sizeof(*si));
			}
		}
		si->si_len = htons((u_short)len);
		/*
		 * queue stuff up for output
		 */
		sbappendrecord(sb, m);
		cb->s_seq++;
	}
	/*
	 * update window
	 */
	{
		register struct sockbuf *sb2 = &so->so_rcv;
		int credit = ((((int)sb2->sb_mbmax) - (int)sb2->sb_mbcnt) /
						((short)cb->s_mtu));
		int alo = cb->s_ack + (credit > 0 ? credit : 0) - 1;

		if (cb->s_alo < alo) {
			/* If the amount we are raising the window
			   is more than his remaining headroom, tell
			   him about it.  In particular, if he is at
			   his limit, any amount at all will do! */
			u_short raise = alo - cb->s_alo;
			u_short headroom = 1 + cb->s_alo - cb->s_ack;

			if(SSEQ_LT(headroom, raise))
				cb->s_flags |= SF_AK;
			cb->s_alo = alo;
		}
	}

	if (cb->s_oobflags & SF_SOOB) {
		/*
		 * must transmit this out of band packet
		 */
		cb->s_oobflags &= ~ SF_SOOB;
	} else {
		/*
		 * Decide what to transmit:
		 * If it is time to retransmit a packet,
		 * send that.
		 * If we have a new packet, send that
		 * (So long as it is in our allocation)
		 * Otherwise, see if it time to bang on them
		 * to ask for our current allocation.
		 */
		if (cb->s_force == (1+TCPT_REXMT)) {
			lookfor = cb->s_rack;
		} else if (SSEQ_LT(cb->s_snt, cb->s_ralo)) {
			lookfor = cb->s_snt + 1;
		} else if (SSEQ_LT(cb->s_ralo, cb->s_seq)) {
			lookfor = 0;
			if (cb->s_timer[TCPT_PERSIST] == 0) {
				spp_setpersist(cb);
				/* tcp has cb->s_rxtshift = 0; here */
			}
		}
		m = sb->sb_mb;
		while (m) {
			si = mtod(m, struct spidp *);
			m = m->m_act;
			if (SSEQ_LT(si->si_seq, cb->s_rack)) {
				if ((sb->sb_flags & SB_WAIT)
				     || so->so_snd.sb_sel)
					 sowwakeup(so);
				sbdroprecord(sb);
				si = 0;
				continue;
			} 
			if (SSEQ_LT(si->si_seq, lookfor))
				continue;
			break;
		}
		if (si && (si->si_seq != lookfor))
			si = 0;
	}
	cb->s_want = lookfor;

	if (si) {
		/*
		 * must make a copy of this packet for
		 * idp_output to monkey with
		 */
		 m = m_copy(dtom(si), 0, (int)M_COPYALL);
		 if (m == NULL)
			return (ENOBUFS);
		 m0 = m;
		 si = mtod(m, struct spidp *);
	} else if (cb->s_force || cb->s_flags & SF_AK) {
		/*
		 * Must send an acknowledgement or a probe
		 */
		m = m_get(M_DONTWAIT, MT_HEADER);
		if (m == 0)
			return (ENOBUFS);
		/*
		 * Fill in mbuf with extended SP header
		 * and addresses and length put into network format.
		 */
		m->m_off = MMAXOFF - sizeof (struct spidp);
		m->m_len = sizeof (*si);
		m->m_next = 0;
		si = mtod(m, struct spidp *);
		*si = cb->s_shdr;
		si->si_seq = cb->s_snt + 1;
		si->si_len = htons(sizeof (*si));
		si->si_cc |= SP_SP;
	}
	/*
	 * Stuff checksum and output datagram.
	 */
	if (si) {
		if (cb->s_flags & (SF_AK|SF_DELACK))
			cb->s_flags &= ~(SF_AK|SF_DELACK);
		/*
		 * If we are almost out of allocation
		 * or one of the timers has gone off
		 * request an ack.
		 */
		if (SSEQ_GEQ(cb->s_seq, cb->s_ralo))
			si->si_cc |= SP_SA;
		if (cb->s_force) {
			si->si_cc |= SP_SA;
			cb->s_force = 0;
		}
		/*
		 * If this is a new packet (and not a system packet),
		 * and we are not currently timing anything,
		 * time this one and ask for an ack.
		 */
		if (SSEQ_LT(cb->s_snt, si->si_seq) && (!(si->si_cc & SP_SP))) {
			cb->s_snt = si->si_seq;
			if (cb->s_rtt == 0) {
				cb->s_rtseq = si->si_seq;
				cb->s_rtt = 1;
				si->si_cc |= SP_SA;
			}
			/*
			 * If the retransmit timer has not been set
			 * and this is a real packet
			 * then start the retransmit timer
			 */
			if (cb->s_timer[TCPT_REXMT] == 0) {
				TCPT_RANGESET(cb->s_timer[TCPT_REXMT],
					tcp_beta * cb->s_srtt, TCPTV_MIN,
					TCPTV_MAX);
				cb->s_rxtshift = 0;
			}
		}
		si->si_seq = htons(si->si_seq);
		si->si_alo = htons(cb->s_alo);
		si->si_ack = htons(cb->s_ack);

		if (idpcksum) {
			si->si_sum = 0;
			len = ntohs(si->si_len);
			if (len & 1)
				len++;
			si->si_sum = ns_cksum(dtom(si), len);
		} else
			si->si_sum = 0xffff;

		if (so->so_options & SO_DEBUG || traceallspps)
			spp_trace(SA_OUTPUT, cb->s_state, cb, si, 0);
		spp_output_cnt++;
		if (so->so_options & SO_DONTROUTE)
			error = ns_output(m, (struct route *)0, NS_ROUTETOIF);
		else
			error = ns_output(m, &cb->s_nspcb->nsp_route, 0);
		if (traceallspps && sppconsdebug) {
			printf("spp_out: %x\n", error);
		}
		if (so->so_options & SO_DEBUG || traceallspps)
			spp_trace(SA_OUTPUT, cb->s_state, cb, si, 0);
	}
	return (error);
}

/*ARGSUSED*/
spp_ctloutput(req, so, level, name, value)
	int req;
	struct socket *so;
	int name;
	struct mbuf **value;
{
	register struct mbuf *m;
	struct nspcb *nsp = sotonspcb(so);
	register struct sppcb *cb;
	int mask, error = 0;

	if (level != NSPROTO_SPP) {
		/* This will have to be changed when we do more general
		   stacking of protocols */
		return (idp_ctloutput(req, so, level, name, value));
	}
	if (nsp == NULL) {
		error = EINVAL;
		goto release;
	} else
		cb = nstosppcb(nsp);

	switch (req) {

	case PRCO_GETOPT:
		if (value == NULL)
			return (EINVAL);
		m = m_get(M_DONTWAIT, MT_DATA);
		if (m == NULL)
			return (ENOBUFS);
		switch (name) {

		case SO_HEADERS_ON_INPUT:
			mask = SF_HI;
			goto get_flags;

		case SO_HEADERS_ON_OUTPUT:
			mask = SF_HO;
		get_flags:
			m->m_len = sizeof(short);
			m->m_off = MMAXOFF - sizeof(short);
			*mtod(m, short *) = cb->s_flags & mask;
			break;

		case SO_MTU:
			m->m_len = sizeof(u_short);
			m->m_off = MMAXOFF - sizeof(short);
			*mtod(m, short *) = cb->s_mtu;
			break;

		case SO_LAST_HEADER:
			m->m_len = sizeof(struct sphdr);
			m->m_off = MMAXOFF - sizeof(struct sphdr);
			*mtod(m, struct sphdr *) = cb->s_rhdr;
			break;

		case SO_DEFAULT_HEADERS:
			m->m_len = sizeof(struct spidp);
			m->m_off = MMAXOFF - sizeof(struct sphdr);
			*mtod(m, struct sphdr *) = cb->s_shdr.si_s;
			break;

		default:
			error = EINVAL;
		}
		*value = m;
		break;

	case PRCO_SETOPT:
		if (value == 0 || *value == 0) {
			error = EINVAL;
			break;
		}
		switch (name) {
			int *ok;

		case SO_HEADERS_ON_INPUT:
			mask = SF_HI;
			goto set_head;

		case SO_HEADERS_ON_OUTPUT:
			mask = SF_HO;
		set_head:
			if (cb->s_flags & SF_PI) {
				ok = mtod(*value, int *);
				if (*ok)
					cb->s_flags |= mask;
				else
					cb->s_flags &= ~mask;
			} else error = EINVAL;
			break;

		case SO_MTU:
			cb->s_mtu = *(mtod(*value, u_short *));
			break;

		case SO_DEFAULT_HEADERS:
			{
				register struct sphdr *sp
						= mtod(*value, struct sphdr *);
				cb->s_dt = sp->sp_dt;
				cb->s_cc = sp->sp_cc & SP_EM;
			}
			break;

		default:
			error = EINVAL;
		}
		m_freem(*value);
		break;
	}
	release:
		return (error);
}

/*ARGSUSED*/
spp_usrreq(so, req, m, nam, rights)
	struct socket *so;
	int req;
	struct mbuf *m, *nam, *rights;
{
	struct nspcb *nsp = sotonspcb(so);
	register struct sppcb *cb;
	int s = splnet();
	int error = 0, ostate;

	if (req == PRU_CONTROL)
                return (ns_control(so, (int)m, (caddr_t)nam,
			(struct ifnet *)rights));
	if (rights && rights->m_len) {
		error = EINVAL;
		goto release;
	}
	if (nsp == NULL) {
		if (req != PRU_ATTACH) {
			error = EINVAL;
			goto release;
		}
	} else
		cb = nstosppcb(nsp);

	ostate = cb ? cb->s_state : 0;

	switch (req) {

	case PRU_ATTACH:
		if (nsp != NULL) {
			error = EISCONN;
			break;
		}
		error = ns_pcballoc(so, &nspcb);
		if (error)
			break;
		error = soreserve(so, 2048, 2048);
		if (error)
			break;
		nsp = sotonspcb(so);
		{
			struct mbuf *mm = m_getclr(M_DONTWAIT, MT_PCB);

			if (mm == NULL) {
				error = ENOBUFS;
				break;
			}
			cb = mtod(mm, struct sppcb *);
			cb->s_state = TCPS_LISTEN;
			cb->s_snt = -1;
			cb->s_q.si_next = cb->s_q.si_prev = &cb->s_q;
			cb->s_nspcb = nsp;
			nsp->nsp_pcb = (caddr_t) cb; 
		}
		break;

	case PRU_DETACH:
		if (nsp == NULL) {
			error = ENOTCONN;
			break;
		}
		if (cb->s_state > TCPS_LISTEN)
			cb = spp_disconnect(cb);
		else
			cb = spp_close(cb);
		break;

	case PRU_BIND:
		error = ns_pcbbind(nsp, nam);
		break;

	case PRU_LISTEN:
		if (nsp->nsp_lport == 0)
			error = ns_pcbbind(nsp, (struct mbuf *)0);
		if (error == 0)
			cb->s_state = TCPS_LISTEN;
		break;

	/*
	 * Initiate connection to peer.
	 * Enter SYN_SENT state, and mark socket as connecting.
	 * Start keep-alive timer, setup prototype header,
	 * Send initial system packet requesting connection.
	 */
	case PRU_CONNECT:
		if (nsp->nsp_lport == 0) {
			error = ns_pcbbind(nsp, (struct mbuf *)0);
			if (error)
				break;
		}
		error = ns_pcbconnect(nsp, nam);
		if (error)
			break;
		soisconnecting(so);
		cb->s_state = TCPS_SYN_SENT;
		cb->s_did = 0;
		spp_template(cb);
		cb->s_timer[TCPT_KEEP] = TCPTV_KEEP;
		cb->s_force = 1 + TCPTV_KEEP;
		/*
		 * Other party is required to respond to
		 * the port I send from, but he is not
		 * required to answer from where I am sending to,
		 * so allow wildcarding.
		 * original port I am sending to is still saved in
		 * cb->s_dport.
		 */
		nsp->nsp_fport = 0;
		error = spp_output(cb, (struct mbuf *) 0);
		break;

	case PRU_CONNECT2:
		error = EOPNOTSUPP;
		break;

	/*
	 * We may decide later to implement connection closing
	 * handshaking at the spp level optionally.
	 * here is the hook to do it:
	 */
	case PRU_DISCONNECT:
		cb = spp_disconnect(cb);
		break;

	/*
	 * Accept a connection.  Essentially all the work is
	 * done at higher levels; just return the address
	 * of the peer, storing through addr.
	 */
	case PRU_ACCEPT: {
		struct sockaddr_ns *sns = mtod(nam, struct sockaddr_ns *);

		nam->m_len = sizeof (struct sockaddr_ns);
		sns->sns_family = AF_NS;
		sns->sns_addr = nsp->nsp_faddr;
		break;
		}

	case PRU_SHUTDOWN:
		socantsendmore(so);
		cb = spp_usrclosed(cb);
		if (cb)
			error = spp_output(cb, (struct mbuf *) 0);
		break;

	/*
	 * After a receive, possibly send acknowledgment
	 * updating allocation.
	 */
	case PRU_RCVD:
		(void) spp_output(cb, (struct mbuf *) 0);
		break;

	case PRU_ABORT:
		(void) spp_drop(cb, ECONNABORTED);
		break;

	case PRU_SENSE:
	case PRU_CONTROL:
		m = NULL;
		error = EOPNOTSUPP;
		break;

	case PRU_RCVOOB:
		if ((cb->s_oobflags & SF_IOOB) || so->so_oobmark ||
		    (so->so_state & SS_RCVATMARK)) {
			m->m_len = 1;
			*mtod(m, caddr_t) = cb->s_iobc;
			break;
		}
		error = EINVAL;
		break;

	case PRU_SENDOOB:
		if (sbspace(&so->so_snd) < -512) {
			error = ENOBUFS;
			break;
		}
		cb->s_oobflags |= SF_SOOB;
		/* fall into */
	case PRU_SEND:
		error = spp_output(cb, m);
		m = NULL;
		break;

	case PRU_SOCKADDR:
		ns_setsockaddr(nsp, nam);
		break;

	case PRU_PEERADDR:
		ns_setpeeraddr(nsp, nam);
		break;

	case PRU_SLOWTIMO:
		cb = spp_timers(cb, (int)nam);
		break;

	case PRU_FASTTIMO:
	case PRU_PROTORCV:
	case PRU_PROTOSEND:
		error =  EOPNOTSUPP;
		break;

	default:
		panic("sp_usrreq");
	}
	if (cb && (so->so_options & SO_DEBUG || traceallspps))
		spp_trace(SA_USER, (u_char)ostate, cb, (struct spidp *)0, req);
release:
	if (m != NULL)
		m_freem(m);
	splx(s);
	return (error);
}

spp_usrreq_sp(so, req, m, nam, rights)
	struct socket *so;
	int req;
	struct mbuf *m, *nam, *rights;
{
	int error = spp_usrreq(so, req, m, nam, rights);

	if (req == PRU_ATTACH && error == 0) {
		struct nspcb *nsp = sotonspcb(so);
		((struct sppcb *)nsp->nsp_pcb)->s_flags |=
					(SF_HI | SF_HO | SF_PI);
	}
	return (error);
}

/*
 * Create template to be used to send spp packets on a connection.
 * Called after host entry created, fills
 * in a skeletal spp header (choosing connection id),
 * minimizing the amount of work necessary when the connection is used.
 */
spp_template(cb)
	struct sppcb *cb;
{
	register struct nspcb *nsp = cb->s_nspcb;
	register struct spidp *n = &(cb->s_shdr);

	cb->s_mtu = 576 - sizeof (struct spidp);
	n->si_pt = NSPROTO_SPP;
	n->si_sna = nsp->nsp_laddr;
	n->si_dna = nsp->nsp_faddr;
	n->si_sid = htons(spp_iss);
	spp_iss += SPP_ISSINCR/2;
	n->si_alo = 1;
}

/*
 * Close a SPIP control block:
 *	discard spp control block itself
 *	discard ns protocol control block
 *	wake up any sleepers
 */
struct sppcb *
spp_close(cb)
	register struct sppcb *cb;
{
	register struct spidp_q *s;
	struct nspcb *nsp = cb->s_nspcb;
	struct socket *so = nsp->nsp_socket;
	register struct mbuf *m;

	s = cb->s_q.si_next;
	while (s != &(cb->s_q)) {
		s = s->si_next;
		m = dtom(s->si_prev);
		remque(s->si_prev);
		m_freem(m);
	}
	(void) m_free(dtom(cb));
	nsp->nsp_pcb = 0;
	soisdisconnected(so);
	ns_pcbdetach(nsp);
	return ((struct sppcb *)0);
}
/*
 *	Someday we may do level 3 handshaking
 *	to close a connection or send a xerox style error.
 *	For now, just close.
 */
struct sppcb *
spp_usrclosed(cb)
	register struct sppcb *cb;
{
	return (spp_close(cb));
}
struct sppcb *
spp_disconnect(cb)
	register struct sppcb *cb;
{
	return (spp_close(cb));
}
/*
 * Drop connection, reporting
 * the specified error.
 */
struct sppcb *
spp_drop(cb, errno)
	register struct sppcb *cb;
	int errno;
{
	struct socket *so = cb->s_nspcb->nsp_socket;

	/*
	 * someday, in the xerox world
	 * we will generate error protocol packets
	 * announcing that the socket has gone away.
	 */
	/*if (TCPS_HAVERCVDSYN(tp->t_state)) {
		tp->t_state = TCPS_CLOSED;
		(void) tcp_output(tp);
	}*/
	so->so_error = errno;
	return (spp_close(cb));
}

spp_abort(nsp)
	struct nspcb *nsp;
{

	(void) spp_close((struct sppcb *)nsp->nsp_pcb);
}

spp_setpersist(cb)
	register struct sppcb *cb;
{

	/*if (cb->s_timer[TCPT_REXMT])
		panic("spp_output REXMT");*/
	/*
	 * Start/restart persistance timer.
	 */
	TCPT_RANGESET(cb->s_timer[TCPT_PERSIST],
	    ((int)(tcp_beta * cb->s_srtt)) << cb->s_rxtshift,
	    TCPTV_PERSMIN, TCPTV_MAX);
	cb->s_rxtshift++;
	if (cb->s_rxtshift >= TCP_MAXRXTSHIFT)
		cb->s_rxtshift = 0;
}
/*
 * Fast timeout routine for processing delayed acks
 */
int spp_ftcnt;
spp_fasttimo()
{
	register struct nspcb *nsp;
	register struct sppcb *cb;
	int s = splnet();

	nsp = nspcb.nsp_next;
	spp_ftcnt++;
	if (nsp)
	for (; nsp != &nspcb; nsp = nsp->nsp_next)
		if ((cb = (struct sppcb *)nsp->nsp_pcb) &&
		    (cb->s_flags & SF_DELACK)) {
			cb->s_flags &= ~SF_DELACK;
			cb->s_flags |= SF_AK;
			(void) spp_output(cb, (struct mbuf *) 0);
		}
	splx(s);
}

/*
 * spp protocol timeout routine called every 500 ms.
 * Updates the timers in all active pcb's and
 * causes finite state machine actions if timers expire.
 */
spp_slowtimo()
{
	register struct nspcb *ip, *ipnxt;
	register struct sppcb *cb;
	int s = splnet();
	register int i;

	/*
	 * Search through tcb's and update active timers.
	 */
	ip = nspcb.nsp_next;
	if (ip == 0) {
		splx(s);
		return;
	}
	while (ip != &nspcb) {
		cb = nstosppcb(ip);
		ipnxt = ip->nsp_next;
		if (cb == 0)
			goto tpgone;
		for (i = 0; i < TCPT_NTIMERS; i++) {
			if (cb->s_timer[i] && --cb->s_timer[i] == 0) {
				(void) spp_usrreq(cb->s_nspcb->nsp_socket,
				    PRU_SLOWTIMO, (struct mbuf *)0,
				    (struct mbuf *)i, (struct mbuf *)0);
				if (ipnxt->nsp_prev != ip)
					goto tpgone;
			}
		}
		cb->s_idle++;
		if (cb->s_rtt)
			cb->s_rtt++;
tpgone:
		ip = ipnxt;
	}
	spp_iss += SPP_ISSINCR/PR_SLOWHZ;		/* increment iss */
	splx(s);
}

float	spp_backoff[TCP_MAXRXTSHIFT] =
    { 1.0, 1.2, 1.4, 1.7, 2.0, 3.0, 5.0, 8.0, 16.0, 32.0 };
int sppexprexmtbackoff = 0;
/*
 * SPP timer processing.
 */
struct sppcb *
spp_timers(cb, timer)
	register struct sppcb *cb;
	int timer;
{

	cb->s_force = 1 + timer;
	switch (timer) {

	/*
	 * 2 MSL timeout in shutdown went off.  Delete connection
	 * control block.
	 */
	case TCPT_2MSL:
		cb = spp_close(cb);
		break;

	/*
	 * Retransmission timer went off.  Message has not
	 * been acked within retransmit interval.  Back off
	 * to a longer retransmit interval and retransmit all
	 * unacknowledged messages in the window.
	 */
	case TCPT_REXMT:
		cb->s_rxtshift++;
		if (cb->s_rxtshift > TCP_MAXRXTSHIFT) {
			cb = spp_drop(cb, ETIMEDOUT);
			break;
		}
		(void) spp_output(cb, (struct mbuf *) 0);
		TCPT_RANGESET(cb->s_timer[TCPT_REXMT],
		    (int)cb->s_srtt, TCPTV_MIN, TCPTV_MAX);
		if (sppexprexmtbackoff) {
			TCPT_RANGESET(cb->s_timer[TCPT_REXMT],
			    cb->s_timer[TCPT_REXMT] << cb->s_rxtshift,
			    TCPTV_MIN, TCPTV_MAX);
		} else {
			TCPT_RANGESET(cb->s_timer[TCPT_REXMT],
			    cb->s_timer[TCPT_REXMT] *
			        spp_backoff[cb->s_rxtshift - 1],
			    TCPTV_MIN, TCPTV_MAX);
		}
		break;

	/*
	 * Persistance timer into zero window.
	 * Force a probe to be sent.
	 */
	case TCPT_PERSIST:
		(void) spp_output(cb, (struct mbuf *) 0);
		spp_setpersist(cb);
		break;

	/*
	 * Keep-alive timer went off; send something
	 * or drop connection if idle for too long.
	 */
	case TCPT_KEEP:
		if (cb->s_state < TCPS_ESTABLISHED)
			goto dropit;
		if (cb->s_nspcb->nsp_socket->so_options & SO_KEEPALIVE) {
		    	if (cb->s_idle >= TCPTV_MAXIDLE)
				goto dropit;
			(void) spp_output(cb, (struct mbuf *) 0);
		} else
			cb->s_idle = 0;
		cb->s_timer[TCPT_KEEP] = TCPTV_KEEP;
		break;
	dropit:
		cb = spp_drop(cb, ETIMEDOUT);
		break;
	}
	return (cb);
}