xref: /csrg-svn/sys/netns/spp_usrreq.c (revision 34486)
1 /*
2  * Copyright (c) 1984, 1985, 1986, 1987 Regents of the University of California.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms are permitted
6  * provided that this notice is preserved and that due credit is given
7  * to the University of California at Berkeley. The name of the University
8  * may not be used to endorse or promote products derived from this
9  * software without specific prior written permission. This software
10  * is provided ``as is'' without express or implied warranty.
11  *
12  *      @(#)spp_usrreq.c	7.7 (Berkeley) 05/25/88
13  */
14 
15 #include "param.h"
16 #include "systm.h"
17 #include "dir.h"
18 #include "user.h"
19 #include "mbuf.h"
20 #include "protosw.h"
21 #include "socket.h"
22 #include "socketvar.h"
23 #include "errno.h"
24 
25 #include "../net/if.h"
26 #include "../net/route.h"
27 #include "../netinet/tcp_fsm.h"
28 
29 #include "ns.h"
30 #include "ns_pcb.h"
31 #include "idp.h"
32 #include "idp_var.h"
33 #include "ns_error.h"
34 #include "sp.h"
35 #include "spidp.h"
36 #include "spp_timer.h"
37 #include "spp_var.h"
38 #include "spp_debug.h"
39 
40 /*
41  * SP protocol implementation.
42  */
43 spp_init()
44 {
45 
46 	spp_iss = 1; /* WRONG !! should fish it out of TODR */
47 }
48 struct spidp spp_savesi;
49 int traceallspps = 0;
50 extern int sppconsdebug;
51 int spp_hardnosed;
52 int spp_use_delack = 0;
53 
54 /*ARGSUSED*/
55 spp_input(m, nsp, ifp)
56 	register struct mbuf *m;
57 	register struct nspcb *nsp;
58 	struct ifnet *ifp;
59 {
60 	register struct sppcb *cb;
61 	register struct spidp *si = mtod(m, struct spidp *);
62 	register struct socket *so;
63 	short ostate;
64 	int dropsocket = 0;
65 
66 
67 	sppstat.spps_rcvtotal++;
68 	if (nsp == 0) {
69 		panic("No nspcb in spp_input\n");
70 		return;
71 	}
72 
73 	cb = nstosppcb(nsp);
74 	if (cb == 0) goto bad;
75 
76 	if (m->m_len < sizeof(*si)) {
77 		if ((m = m_pullup(m, sizeof(*si))) == 0) {
78 			sppstat.spps_rcvshort++;
79 			return;
80 		}
81 		si = mtod(m, struct spidp *);
82 	}
83 	si->si_seq = ntohs(si->si_seq);
84 	si->si_ack = ntohs(si->si_ack);
85 	si->si_alo = ntohs(si->si_alo);
86 
87 	so = nsp->nsp_socket;
88 	if (so->so_options & SO_DEBUG || traceallspps) {
89 		ostate = cb->s_state;
90 		spp_savesi = *si;
91 	}
92 	if (so->so_options & SO_ACCEPTCONN) {
93 		struct sppcb *ocb = cb;
94 
95 		so = sonewconn(so);
96 		if (so == 0) {
97 			goto drop;
98 		}
99 		/*
100 		 * This is ugly, but ....
101 		 *
102 		 * Mark socket as temporary until we're
103 		 * committed to keeping it.  The code at
104 		 * ``drop'' and ``dropwithreset'' check the
105 		 * flag dropsocket to see if the temporary
106 		 * socket created here should be discarded.
107 		 * We mark the socket as discardable until
108 		 * we're committed to it below in TCPS_LISTEN.
109 		 */
110 		dropsocket++;
111 		nsp = (struct nspcb *)so->so_pcb;
112 		nsp->nsp_laddr = si->si_dna;
113 		cb = nstosppcb(nsp);
114 		cb->s_mtu = ocb->s_mtu;		/* preserve sockopts */
115 		cb->s_flags = ocb->s_flags;	/* preserve sockopts */
116 		cb->s_state = TCPS_LISTEN;
117 	}
118 
119 	/*
120 	 * Packet received on connection.
121 	 * reset idle time and keep-alive timer;
122 	 */
123 	cb->s_idle = 0;
124 	cb->s_timer[SPPT_KEEP] = SPPTV_KEEP;
125 
126 	switch (cb->s_state) {
127 
128 	case TCPS_LISTEN:{
129 		struct mbuf *am;
130 		register struct sockaddr_ns *sns;
131 		struct ns_addr laddr;
132 
133 		/*
134 		 * If somebody here was carying on a conversation
135 		 * and went away, and his pen pal thinks he can
136 		 * still talk, we get the misdirected packet.
137 		 */
138 		if (spp_hardnosed && (si->si_did != 0 || si->si_seq != 0)) {
139 			spp_istat.gonawy++;
140 			goto dropwithreset;
141 		}
142 		am = m_get(M_DONTWAIT, MT_SONAME);
143 		if (am == NULL)
144 			goto drop;
145 		am->m_len = sizeof (struct sockaddr_ns);
146 		sns = mtod(am, struct sockaddr_ns *);
147 		sns->sns_family = AF_NS;
148 		sns->sns_addr = si->si_sna;
149 		laddr = nsp->nsp_laddr;
150 		if (ns_nullhost(laddr))
151 			nsp->nsp_laddr = si->si_dna;
152 		if (ns_pcbconnect(nsp, am)) {
153 			nsp->nsp_laddr = laddr;
154 			(void) m_free(am);
155 			spp_istat.noconn++;
156 			goto drop;
157 		}
158 		(void) m_free(am);
159 		spp_template(cb);
160 		dropsocket = 0;		/* committed to socket */
161 		cb->s_did = si->si_sid;
162 		cb->s_rack = si->si_ack;
163 		cb->s_ralo = si->si_alo;
164 #define THREEWAYSHAKE
165 #ifdef THREEWAYSHAKE
166 		cb->s_state = TCPS_SYN_RECEIVED;
167 		cb->s_force = 1 + SPPT_KEEP;
168 		sppstat.spps_accepts++;
169 		cb->s_timer[SPPT_KEEP] = SPPTV_KEEP;
170 		}
171 		break;
172 	/*
173 	 * This state means that we have heard a response
174 	 * to our acceptance of their connection
175 	 * It is probably logically unnecessary in this
176 	 * implementation.
177 	 */
178 	 case TCPS_SYN_RECEIVED: {
179 		if (si->si_did!=cb->s_sid) {
180 			spp_istat.wrncon++;
181 			goto drop;
182 		}
183 #endif
184 		nsp->nsp_fport =  si->si_sport;
185 		cb->s_timer[SPPT_REXMT] = 0;
186 		cb->s_timer[SPPT_KEEP] = SPPTV_KEEP;
187 		soisconnected(so);
188 		cb->s_state = TCPS_ESTABLISHED;
189 		sppstat.spps_accepts++;
190 		}
191 		break;
192 
193 	/*
194 	 * This state means that we have gotten a response
195 	 * to our attempt to establish a connection.
196 	 * We fill in the data from the other side,
197 	 * telling us which port to respond to, instead of the well-
198 	 * known one we might have sent to in the first place.
199 	 * We also require that this is a response to our
200 	 * connection id.
201 	 */
202 	case TCPS_SYN_SENT:
203 		if (si->si_did!=cb->s_sid) {
204 			spp_istat.notme++;
205 			goto drop;
206 		}
207 		sppstat.spps_connects++;
208 		cb->s_did = si->si_sid;
209 		cb->s_rack = si->si_ack;
210 		cb->s_ralo = si->si_alo;
211 		cb->s_dport = nsp->nsp_fport =  si->si_sport;
212 		cb->s_timer[SPPT_REXMT] = 0;
213 		cb->s_flags |= SF_ACKNOW;
214 		soisconnected(so);
215 		cb->s_state = TCPS_ESTABLISHED;
216 		/* Use roundtrip time of connection request for initial rtt */
217 		if (cb->s_rtt) {
218 			cb->s_srtt = cb->s_rtt << 3;
219 			cb->s_rttvar = cb->s_rtt << 1;
220 			SPPT_RANGESET(cb->s_rxtcur,
221 			    ((cb->s_srtt >> 2) + cb->s_rttvar) >> 1,
222 			    SPPTV_MIN, SPPTV_REXMTMAX);
223 			    cb->s_rtt = 0;
224 		}
225 	}
226 	if (so->so_options & SO_DEBUG || traceallspps)
227 		spp_trace(SA_INPUT, (u_char)ostate, cb, &spp_savesi, 0);
228 
229 	m->m_len -= sizeof (struct idp);
230 	m->m_off += sizeof (struct idp);
231 
232 	if (spp_reass(cb, si)) {
233 		(void) m_freem(m);
234 	}
235 	if (cb->s_force || (cb->s_flags & (SF_ACKNOW|SF_WIN|SF_RXT)))
236 		(void) spp_output(cb, (struct mbuf *)0);
237 	cb->s_flags &= ~(SF_WIN|SF_RXT);
238 	return;
239 
240 dropwithreset:
241 	if (dropsocket)
242 		(void) soabort(so);
243 	si->si_seq = ntohs(si->si_seq);
244 	si->si_ack = ntohs(si->si_ack);
245 	si->si_alo = ntohs(si->si_alo);
246 	ns_error(dtom(si), NS_ERR_NOSOCK, 0);
247 	if (cb->s_nspcb->nsp_socket->so_options & SO_DEBUG || traceallspps)
248 		spp_trace(SA_DROP, (u_char)ostate, cb, &spp_savesi, 0);
249 	return;
250 
251 drop:
252 bad:
253 	if (cb == 0 || cb->s_nspcb->nsp_socket->so_options & SO_DEBUG ||
254             traceallspps)
255 		spp_trace(SA_DROP, (u_char)ostate, cb, &spp_savesi, 0);
256 	m_freem(m);
257 }
258 
259 int spprexmtthresh = 3;
260 
261 /*
262  * This is structurally similar to the tcp reassembly routine
263  * but its function is somewhat different:  It merely queues
264  * packets up, and suppresses duplicates.
265  */
266 spp_reass(cb, si)
267 register struct sppcb *cb;
268 register struct spidp *si;
269 {
270 	register struct spidp_q *q;
271 	register struct mbuf *m;
272 	register struct socket *so = cb->s_nspcb->nsp_socket;
273 	char packetp = cb->s_flags & SF_HI;
274 	int incr;
275 	char wakeup = 0;
276 
277 	if (si == SI(0))
278 		goto present;
279 	/*
280 	 * Update our news from them.
281 	 */
282 	if (si->si_cc & SP_SA)
283 		cb->s_flags |= (spp_use_delack ? SF_DELACK : SF_ACKNOW);
284 	if (SSEQ_GT(si->si_alo, cb->s_ralo))
285 		cb->s_flags |= SF_WIN;
286 	if (SSEQ_LEQ(si->si_ack, cb->s_rack)) {
287 		if ((si->si_cc & SP_SP) && cb->s_rack != (cb->s_smax + 1)) {
288 			sppstat.spps_rcvdupack++;
289 			/*
290 			 * If this is a completely duplicate ack
291 			 * and other conditions hold, we assume
292 			 * a packet has been dropped and retransmit
293 			 * it exactly as in tcp_input().
294 			 */
295 			if (si->si_ack != cb->s_rack ||
296 			    si->si_alo != cb->s_ralo)
297 				cb->s_dupacks = 0;
298 			else if (++cb->s_dupacks == spprexmtthresh) {
299 				u_short onxt = cb->s_snxt;
300 				int cwnd = cb->s_cwnd;
301 
302 				cb->s_snxt = si->si_ack;
303 				cb->s_cwnd = CUNIT;
304 				cb->s_force = 1 + SPPT_REXMT;
305 				(void) spp_output(cb, (struct mbuf *)0);
306 				cb->s_timer[SPPT_REXMT] = cb->s_rxtcur;
307 				cb->s_rtt = 0;
308 				if (cwnd >= 4 * CUNIT)
309 					cb->s_cwnd = cwnd / 2;
310 				if (SSEQ_GT(onxt, cb->s_snxt))
311 					cb->s_snxt = onxt;
312 				return (1);
313 			}
314 		} else
315 			cb->s_dupacks = 0;
316 		goto update_window;
317 	}
318 	cb->s_dupacks = 0;
319 	/*
320 	 * If our correspondent acknowledges data we haven't sent
321 	 * TCP would drop the packet after acking.  We'll be a little
322 	 * more permissive
323 	 */
324 	if (SSEQ_GT(si->si_ack, (cb->s_smax + 1))) {
325 		sppstat.spps_rcvacktoomuch++;
326 		si->si_ack = cb->s_smax + 1;
327 	}
328 	sppstat.spps_rcvackpack++;
329 	/*
330 	 * If transmit timer is running and timed sequence
331 	 * number was acked, update smoothed round trip time.
332 	 * See discussion of algorithm in tcp_input.c
333 	 */
334 	if (cb->s_rtt && SSEQ_GT(si->si_ack, cb->s_rtseq)) {
335 		sppstat.spps_rttupdated++;
336 		if (cb->s_srtt != 0) {
337 			register short delta;
338 			delta = cb->s_rtt - (cb->s_srtt >> 3);
339 			if ((cb->s_srtt += delta) <= 0)
340 				cb->s_srtt = 1;
341 			if (delta < 0)
342 				delta = -delta;
343 			delta -= (cb->s_rttvar >> 2);
344 			if ((cb->s_rttvar += delta) <= 0)
345 				cb->s_rttvar = 1;
346 		} else {
347 			/*
348 			 * No rtt measurement yet
349 			 */
350 			cb->s_srtt = cb->s_rtt << 3;
351 			cb->s_rttvar = cb->s_rtt << 1;
352 		}
353 		cb->s_rtt = 0;
354 		cb->s_rxtshift = 0;
355 		SPPT_RANGESET(cb->s_rxtcur,
356 			((cb->s_srtt >> 2) + cb->s_rttvar) >> 1,
357 			SPPTV_MIN, SPPTV_REXMTMAX);
358 	}
359 	/*
360 	 * If all outstanding data is acked, stop retransmit
361 	 * timer and remember to restart (more output or persist).
362 	 * If there is more data to be acked, restart retransmit
363 	 * timer, using current (possibly backed-off) value;
364 	 */
365 	if (si->si_ack == cb->s_smax + 1) {
366 		cb->s_timer[SPPT_REXMT] = 0;
367 		cb->s_flags |= SF_RXT;
368 	} else if (cb->s_timer[SPPT_PERSIST] == 0)
369 		cb->s_timer[SPPT_REXMT] = cb->s_rxtcur;
370 	/*
371 	 * When new data is acked, open the congestion window.
372 	 * If the window gives us less than ssthresh packets
373 	 * in flight, open exponentially (maxseg at a time).
374 	 * Otherwise open linearly (maxseg^2 / cwnd at a time).
375 	 */
376 	incr = CUNIT;
377 	if (cb->s_cwnd > cb->s_ssthresh)
378 		incr = MAX(incr * incr / cb->s_cwnd, 1);
379 	cb->s_cwnd = MIN(cb->s_cwnd + incr, cb->s_cwmx);
380 	/*
381 	 * Trim Acked data from output queue.
382 	 */
383 	while ((m = so->so_snd.sb_mb) != NULL) {
384 		if (SSEQ_LT((mtod(m, struct spidp *))->si_seq, si->si_ack))
385 			sbdroprecord(&so->so_snd);
386 		else
387 			break;
388 	}
389 	if ((so->so_snd.sb_flags & SB_WAIT) || so->so_snd.sb_sel)
390 		 sowwakeup(so);
391 	cb->s_rack = si->si_ack;
392 update_window:
393 	if (SSEQ_LT(cb->s_snxt, cb->s_rack))
394 		cb->s_snxt = cb->s_rack;
395 	if (SSEQ_LT(cb->s_swl1, si->si_seq) || cb->s_swl1 == si->si_seq &&
396 	    (SSEQ_LT(cb->s_swl2, si->si_ack) ||
397 	     cb->s_swl2 == si->si_ack && SSEQ_LT(cb->s_ralo, si->si_alo))) {
398 		/* keep track of pure window updates */
399 		if ((si->si_cc & SP_SP) && cb->s_swl2 == si->si_ack
400 		    && SSEQ_LT(cb->s_ralo, si->si_alo)) {
401 			sppstat.spps_rcvwinupd++;
402 			sppstat.spps_rcvdupack--;
403 		}
404 		cb->s_ralo = si->si_alo;
405 		cb->s_swl1 = si->si_seq;
406 		cb->s_swl2 = si->si_ack;
407 		cb->s_swnd = (1 + si->si_alo - si->si_ack);
408 		if (cb->s_swnd > cb->s_smxw)
409 			cb->s_smxw = cb->s_swnd;
410 		cb->s_flags |= SF_WIN;
411 	}
412 	/*
413 	 * If this packet number is higher than that which
414 	 * we have allocated refuse it, unless urgent
415 	 */
416 	if (SSEQ_GT(si->si_seq, cb->s_alo)) {
417 		if (si->si_cc & SP_SP) {
418 			sppstat.spps_rcvwinprobe++;
419 			return (1);
420 		} else
421 			sppstat.spps_rcvpackafterwin++;
422 		if (si->si_cc & SP_OB) {
423 			if (SSEQ_GT(si->si_seq, cb->s_alo + 60)) {
424 				ns_error(dtom(si), NS_ERR_FULLUP, 0);
425 				return (0);
426 			} /* else queue this packet; */
427 		} else {
428 			/*register struct socket *so = cb->s_nspcb->nsp_socket;
429 			if (so->so_state && SS_NOFDREF) {
430 				ns_error(dtom(si), NS_ERR_NOSOCK, 0);
431 				(void)spp_close(cb);
432 			} else
433 				       would crash system*/
434 			spp_istat.notyet++;
435 			ns_error(dtom(si), NS_ERR_FULLUP, 0);
436 			return (0);
437 		}
438 	}
439 	/*
440 	 * If this is a system packet, we don't need to
441 	 * queue it up, and won't update acknowledge #
442 	 */
443 	if (si->si_cc & SP_SP) {
444 		return (1);
445 	}
446 	/*
447 	 * We have already seen this packet, so drop.
448 	 */
449 	if (SSEQ_LT(si->si_seq, cb->s_ack)) {
450 		spp_istat.bdreas++;
451 		sppstat.spps_rcvduppack++;
452 		if (si->si_seq == cb->s_ack - 1)
453 			spp_istat.lstdup++;
454 		return (1);
455 	}
456 	/*
457 	 * Loop through all packets queued up to insert in
458 	 * appropriate sequence.
459 	 */
460 	for (q = cb->s_q.si_next; q!=&cb->s_q; q = q->si_next) {
461 		if (si->si_seq == SI(q)->si_seq) {
462 			sppstat.spps_rcvduppack++;
463 			return (1);
464 		}
465 		if (SSEQ_LT(si->si_seq, SI(q)->si_seq)) {
466 			sppstat.spps_rcvoopack++;
467 			break;
468 		}
469 	}
470 	insque(si, q->si_prev);
471 	/*
472 	 * If this packet is urgent, inform process
473 	 */
474 	if (si->si_cc & SP_OB) {
475 		cb->s_iobc = ((char *)si)[1 + sizeof(*si)];
476 		sohasoutofband(so);
477 		cb->s_oobflags |= SF_IOOB;
478 	}
479 present:
480 #define SPINC sizeof(struct sphdr)
481 	/*
482 	 * Loop through all packets queued up to update acknowledge
483 	 * number, and present all acknowledged data to user;
484 	 * If in packet interface mode, show packet headers.
485 	 */
486 	for (q = cb->s_q.si_next; q!=&cb->s_q; q = q->si_next) {
487 		  if (SI(q)->si_seq == cb->s_ack) {
488 			cb->s_ack++;
489 			m = dtom(q);
490 			if (SI(q)->si_cc & SP_OB) {
491 				cb->s_oobflags &= ~SF_IOOB;
492 				if (so->so_rcv.sb_cc)
493 					so->so_oobmark = so->so_rcv.sb_cc;
494 				else
495 					so->so_state |= SS_RCVATMARK;
496 			}
497 			q = q->si_prev;
498 			remque(q->si_next);
499 			wakeup = 1;
500 			sppstat.spps_rcvpack++;
501 			if (packetp) {
502 				sbappendrecord(&so->so_rcv, m);
503 			} else {
504 				cb->s_rhdr = *mtod(m, struct sphdr *);
505 				m->m_off += SPINC;
506 				m->m_len -= SPINC;
507 				sbappend(&so->so_rcv, m);
508 			}
509 		  } else
510 			break;
511 	}
512 	if (wakeup) sorwakeup(so);
513 	return (0);
514 }
515 
516 spp_ctlinput(cmd, arg)
517 	int cmd;
518 	caddr_t arg;
519 {
520 	struct ns_addr *na;
521 	extern u_char nsctlerrmap[];
522 	extern spp_abort(), spp_quench();
523 	extern struct nspcb *idp_drop();
524 	struct ns_errp *errp;
525 	struct nspcb *nsp;
526 	struct sockaddr_ns *sns;
527 	int type;
528 
529 	if (cmd < 0 || cmd > PRC_NCMDS)
530 		return;
531 	type = NS_ERR_UNREACH_HOST;
532 
533 	switch (cmd) {
534 
535 	case PRC_ROUTEDEAD:
536 		return;
537 
538 	case PRC_IFDOWN:
539 	case PRC_HOSTDEAD:
540 	case PRC_HOSTUNREACH:
541 		sns = (struct sockaddr_ns *)arg;
542 		if (sns->sns_family != AF_NS)
543 			return;
544 		na = &sns->sns_addr;
545 		break;
546 
547 	default:
548 		errp = (struct ns_errp *)arg;
549 		na = &errp->ns_err_idp.idp_dna;
550 		type = errp->ns_err_num;
551 		type = ntohs((u_short)type);
552 	}
553 	switch (type) {
554 
555 	case NS_ERR_UNREACH_HOST:
556 		ns_pcbnotify(na, (int)nsctlerrmap[cmd], spp_abort, (long) 0);
557 		break;
558 
559 	case NS_ERR_TOO_BIG:
560 	case NS_ERR_NOSOCK:
561 		nsp = ns_pcblookup(na, errp->ns_err_idp.idp_sna.x_port,
562 			NS_WILDCARD);
563 		if (nsp) {
564 			if(nsp->nsp_pcb)
565 				(void) spp_drop((struct sppcb *)nsp->nsp_pcb,
566 						(int)nsctlerrmap[cmd]);
567 			else
568 				(void) idp_drop(nsp, (int)nsctlerrmap[cmd]);
569 		}
570 		break;
571 
572 	case NS_ERR_FULLUP:
573 		ns_pcbnotify(na, 0, spp_quench, (long) 0);
574 	}
575 }
576 /*
577  * When a source quench is received, close congestion window
578  * to one packet.  We will gradually open it again as we proceed.
579  */
580 spp_quench(nsp)
581 	struct nspcb *nsp;
582 {
583 	struct sppcb *cb = nstosppcb(nsp);
584 
585 	if (cb)
586 		cb->s_cwnd = CUNIT;
587 }
588 
589 #ifdef notdef
590 int
591 spp_fixmtu(nsp)
592 register struct nspcb *nsp;
593 {
594 	register struct sppcb *cb = (struct sppcb *)(nsp->nsp_pcb);
595 	register struct mbuf *m;
596 	register struct spidp *si;
597 	struct ns_errp *ep;
598 	struct sockbuf *sb;
599 	int badseq, len;
600 	struct mbuf *firstbad, *m0;
601 
602 	if (cb) {
603 		/*
604 		 * The notification that we have sent
605 		 * too much is bad news -- we will
606 		 * have to go through queued up so far
607 		 * splitting ones which are too big and
608 		 * reassigning sequence numbers and checksums.
609 		 * we should then retransmit all packets from
610 		 * one above the offending packet to the last one
611 		 * we had sent (or our allocation)
612 		 * then the offending one so that the any queued
613 		 * data at our destination will be discarded.
614 		 */
615 		 ep = (struct ns_errp *)nsp->nsp_notify_param;
616 		 sb = &nsp->nsp_socket->so_snd;
617 		 cb->s_mtu = ep->ns_err_param;
618 		 badseq = SI(&ep->ns_err_idp)->si_seq;
619 		 for (m = sb->sb_mb; m; m = m->m_act) {
620 			si = mtod(m, struct spidp *);
621 			if (si->si_seq == badseq)
622 				break;
623 		 }
624 		 if (m == 0) return;
625 		 firstbad = m;
626 		 /*for (;;) {*/
627 			/* calculate length */
628 			for (m0 = m, len = 0; m ; m = m->m_next)
629 				len += m->m_len;
630 			if (len > cb->s_mtu) {
631 			}
632 		/* FINISH THIS
633 		} */
634 	}
635 }
636 #endif
637 
638 spp_output(cb, m0)
639 	register struct sppcb *cb;
640 	struct mbuf *m0;
641 {
642 	struct socket *so = cb->s_nspcb->nsp_socket;
643 	register struct mbuf *m;
644 	register struct spidp *si = (struct spidp *) 0;
645 	register struct sockbuf *sb = &so->so_snd;
646 	int len = 0, win, rcv_win;
647 	short span, off;
648 	u_short alo;
649 	int error = 0, sendalot;
650 #ifdef notdef
651 	int idle;
652 #endif
653 	struct mbuf *mprev;
654 	extern int idpcksum;
655 
656 	if (m0) {
657 		int mtu = cb->s_mtu;
658 		int datalen;
659 		/*
660 		 * Make sure that packet isn't too big.
661 		 */
662 		for (m = m0; m ; m = m->m_next) {
663 			mprev = m;
664 			len += m->m_len;
665 		}
666 		datalen = (cb->s_flags & SF_HO) ?
667 				len - sizeof (struct sphdr) : len;
668 		if (datalen > mtu) {
669 			if (cb->s_flags & SF_PI) {
670 				m_freem(m0);
671 				return (EMSGSIZE);
672 			} else {
673 				int oldEM = cb->s_cc & SP_EM;
674 
675 				cb->s_cc &= ~SP_EM;
676 				while (len > mtu) {
677 					m = m_copy(m0, 0, mtu);
678 					if (m == NULL) {
679 						error = ENOBUFS;
680 						goto bad_copy;
681 					}
682 					error = spp_output(cb, m);
683 					if (error) {
684 					bad_copy:
685 						cb->s_cc |= oldEM;
686 						m_freem(m0);
687 						return(error);
688 					}
689 					m_adj(m0, mtu);
690 					len -= mtu;
691 				}
692 				cb->s_cc |= oldEM;
693 			}
694 		}
695 		/*
696 		 * Force length even, by adding a "garbage byte" if
697 		 * necessary.
698 		 */
699 		if (len & 1) {
700 			m = mprev;
701 			if (m->m_len + m->m_off < MMAXOFF)
702 				m->m_len++;
703 			else {
704 				struct mbuf *m1 = m_get(M_DONTWAIT, MT_DATA);
705 
706 				if (m1 == 0) {
707 					m_freem(m0);
708 					return (ENOBUFS);
709 				}
710 				m1->m_len = 1;
711 				m1->m_off = MMAXOFF - 1;
712 				m->m_next = m1;
713 			}
714 		}
715 		m = m_get(M_DONTWAIT, MT_HEADER);
716 		if (m == 0) {
717 			m_freem(m0);
718 			return (ENOBUFS);
719 		}
720 		/*
721 		 * Fill in mbuf with extended SP header
722 		 * and addresses and length put into network format.
723 		 * Long align so prepended ip headers will work on Gould.
724 		 */
725 		m->m_off = MMAXOFF - sizeof (struct spidp) - 2;
726 		m->m_len = sizeof (struct spidp);
727 		m->m_next = m0;
728 		si = mtod(m, struct spidp *);
729 		si->si_i = *cb->s_idp;
730 		si->si_s = cb->s_shdr;
731 		if ((cb->s_flags & SF_PI) && (cb->s_flags & SF_HO)) {
732 			register struct sphdr *sh;
733 			if (m0->m_len < sizeof (*sh)) {
734 				if((m0 = m_pullup(m0, sizeof(*sh))) == NULL) {
735 					(void) m_free(m);
736 					m_freem(m0);
737 					return (EINVAL);
738 				}
739 				m->m_next = m0;
740 			}
741 			sh = mtod(m0, struct sphdr *);
742 			si->si_dt = sh->sp_dt;
743 			si->si_cc |= sh->sp_cc & SP_EM;
744 			m0->m_len -= sizeof (*sh);
745 			m0->m_off += sizeof (*sh);
746 			len -= sizeof (*sh);
747 		}
748 		len += sizeof(*si);
749 		if (cb->s_oobflags & SF_SOOB) {
750 			/*
751 			 * Per jqj@cornell:
752 			 * make sure OB packets convey exactly 1 byte.
753 			 * If the packet is 1 byte or larger, we
754 			 * have already guaranted there to be at least
755 			 * one garbage byte for the checksum, and
756 			 * extra bytes shouldn't hurt!
757 			 */
758 			if (len > sizeof(*si)) {
759 				si->si_cc |= SP_OB;
760 				len = (1 + sizeof(*si));
761 			}
762 		}
763 		si->si_len = htons((u_short)len);
764 		/*
765 		 * queue stuff up for output
766 		 */
767 		sbappendrecord(sb, m);
768 		cb->s_seq++;
769 	}
770 #ifdef notdef
771 	idle = (cb->s_smax == (cb->s_rack - 1));
772 #endif
773 again:
774 	sendalot = 0;
775 	off = cb->s_snxt - cb->s_rack;
776 	win = MIN(cb->s_swnd, (cb->s_cwnd/CUNIT));
777 
778 	/*
779 	 * If in persist timeout with window of 0, send a probe.
780 	 * Otherwise, if window is small but nonzero
781 	 * and timer expired, send what we can and go into
782 	 * transmit state.
783 	 */
784 	if (cb->s_force == 1 + SPPT_PERSIST) {
785 		if (win != 0) {
786 			cb->s_timer[SPPT_PERSIST] = 0;
787 			cb->s_rxtshift = 0;
788 		}
789 	}
790 	span = cb->s_seq - cb->s_rack;
791 	len = MIN(span, win) - off;
792 
793 	if (len < 0) {
794 		/*
795 		 * Window shrank after we went into it.
796 		 * If window shrank to 0, cancel pending
797 		 * restransmission and pull s_snxt back
798 		 * to (closed) window.  We will enter persist
799 		 * state below.  If the widndow didn't close completely,
800 		 * just wait for an ACK.
801 		 */
802 		len = 0;
803 		if (win == 0) {
804 			cb->s_timer[SPPT_REXMT] = 0;
805 			cb->s_snxt = cb->s_rack;
806 		}
807 	}
808 	if (len > 1)
809 		sendalot = 1;
810 	rcv_win = sbspace(&so->so_rcv);
811 
812 	/*
813 	 * Send if we owe peer an ACK.
814 	 */
815 	if (cb->s_oobflags & SF_SOOB) {
816 		/*
817 		 * must transmit this out of band packet
818 		 */
819 		cb->s_oobflags &= ~ SF_SOOB;
820 		sendalot = 1;
821 		sppstat.spps_sndurg++;
822 		goto found;
823 	}
824 	if (cb->s_flags & SF_ACKNOW)
825 		goto send;
826 	if (cb->s_state < TCPS_ESTABLISHED)
827 		goto send;
828 	/*
829 	 * Silly window can't happen in spp.
830 	 * Code from tcp deleted.
831 	 */
832 	if (len)
833 		goto send;
834 	/*
835 	 * Compare available window to amount of window
836 	 * known to peer (as advertised window less
837 	 * next expected input.)  If the difference is at least two
838 	 * packets or at least 35% of the mximum possible window,
839 	 * then want to send a window update to peer.
840 	 */
841 	if (rcv_win > 0) {
842 		u_short delta =  1 + cb->s_alo - cb->s_ack;
843 		int adv = rcv_win - (delta * cb->s_mtu);
844 
845 		if ((so->so_rcv.sb_cc == 0 && adv >= (2 * cb->s_mtu)) ||
846 		    (100 * adv / so->so_rcv.sb_hiwat >= 35)) {
847 			sppstat.spps_sndwinup++;
848 			cb->s_flags |= SF_ACKNOW;
849 			goto send;
850 		}
851 
852 	}
853 	/*
854 	 * Many comments from tcp_output.c are appropriate here
855 	 * including . . .
856 	 * If send window is too small, there is data to transmit, and no
857 	 * retransmit or persist is pending, then go to persist state.
858 	 * If nothing happens soon, send when timer expires:
859 	 * if window is nonzero, transmit what we can,
860 	 * otherwise send a probe.
861 	 */
862 	if (so->so_snd.sb_cc && cb->s_timer[SPPT_REXMT] == 0 &&
863 		cb->s_timer[SPPT_PERSIST] == 0) {
864 			cb->s_rxtshift = 0;
865 			spp_setpersist(cb);
866 	}
867 	/*
868 	 * No reason to send a packet, just return.
869 	 */
870 	cb->s_outx = 1;
871 	return (0);
872 
873 send:
874 	/*
875 	 * Find requested packet.
876 	 */
877 	si = 0;
878 	if (len > 0) {
879 		cb->s_want = cb->s_snxt;
880 		for (m = sb->sb_mb; m; m = m->m_act) {
881 			si = mtod(m, struct spidp *);
882 			if (SSEQ_LEQ(cb->s_snxt, si->si_seq))
883 				break;
884 		}
885 	found:
886 		if (si) {
887 			if (si->si_seq == cb->s_snxt)
888 					cb->s_snxt++;
889 				else
890 					sppstat.spps_sndvoid++, si = 0;
891 		}
892 	}
893 	/*
894 	 * update window
895 	 */
896 	if (rcv_win < 0)
897 		rcv_win = 0;
898 	alo = cb->s_ack - 1 + (rcv_win / ((short)cb->s_mtu));
899 	if (SSEQ_LT(alo, cb->s_alo))
900 		alo = cb->s_alo;
901 
902 	if (si) {
903 		/*
904 		 * must make a copy of this packet for
905 		 * idp_output to monkey with
906 		 */
907 		m = m_copy(dtom(si), 0, (int)M_COPYALL);
908 		if (m == NULL) {
909 			return (ENOBUFS);
910 		}
911 		m0 = m;
912 		si = mtod(m, struct spidp *);
913 		if (SSEQ_LT(si->si_seq, cb->s_smax))
914 			sppstat.spps_sndrexmitpack++;
915 		else
916 			sppstat.spps_sndpack++;
917 	} else if (cb->s_force || cb->s_flags & SF_ACKNOW) {
918 		/*
919 		 * Must send an acknowledgement or a probe
920 		 */
921 		if (cb->s_force)
922 			sppstat.spps_sndprobe++;
923 		if (cb->s_flags & SF_ACKNOW)
924 			sppstat.spps_sndacks++;
925 		m = m_get(M_DONTWAIT, MT_HEADER);
926 		if (m == 0) {
927 			return (ENOBUFS);
928 		}
929 		/*
930 		 * Fill in mbuf with extended SP header
931 		 * and addresses and length put into network format.
932 		 * Allign beginning of packet to long to prepend
933 		 * ifp's on loopback, or NSIP encaspulation for fussy cpu's.
934 		 */
935 		m->m_off = MMAXOFF - sizeof (struct spidp) - 2;
936 		m->m_len = sizeof (*si);
937 		m->m_next = 0;
938 		si = mtod(m, struct spidp *);
939 		si->si_i = *cb->s_idp;
940 		si->si_s = cb->s_shdr;
941 		si->si_seq = cb->s_smax + 1;
942 		si->si_len = htons(sizeof (*si));
943 		si->si_cc |= SP_SP;
944 	} else {
945 		cb->s_outx = 3;
946 		if (so->so_options & SO_DEBUG || traceallspps)
947 			spp_trace(SA_OUTPUT, cb->s_state, cb, si, 0);
948 		return (0);
949 	}
950 	/*
951 	 * Stuff checksum and output datagram.
952 	 */
953 	if ((si->si_cc & SP_SP) == 0) {
954 		if (cb->s_force != (1 + SPPT_PERSIST) ||
955 		    cb->s_timer[SPPT_PERSIST] == 0) {
956 			/*
957 			 * If this is a new packet and we are not currently
958 			 * timing anything, time this one.
959 			 */
960 			if (SSEQ_LT(cb->s_smax, si->si_seq)) {
961 				cb->s_smax = si->si_seq;
962 				if (cb->s_rtt == 0) {
963 					sppstat.spps_segstimed++;
964 					cb->s_rtseq = si->si_seq;
965 					cb->s_rtt = 1;
966 				}
967 			}
968 			/*
969 			 * Set rexmt timer if not currently set,
970 			 * Initial value for retransmit timer is smoothed
971 			 * round-trip time + 2 * round-trip time variance.
972 			 * Initialize shift counter which is used for backoff
973 			 * of retransmit time.
974 			 */
975 			if (cb->s_timer[SPPT_REXMT] == 0 &&
976 			    cb->s_snxt != cb->s_rack) {
977 				cb->s_timer[SPPT_REXMT] = cb->s_rxtcur;
978 				if (cb->s_timer[SPPT_PERSIST]) {
979 					cb->s_timer[SPPT_PERSIST] = 0;
980 					cb->s_rxtshift = 0;
981 				}
982 			}
983 		} else if (SSEQ_LT(cb->s_smax, si->si_seq)) {
984 			cb->s_smax = si->si_seq;
985 		}
986 	} else if (cb->s_state < TCPS_ESTABLISHED) {
987 		if (cb->s_rtt == 0)
988 			cb->s_rtt = 1; /* Time initial handshake */
989 		if (cb->s_timer[SPPT_REXMT] == 0)
990 			cb->s_timer[SPPT_REXMT] = cb->s_rxtcur;
991 	}
992 	{
993 		/*
994 		 * Do not request acks when we ack their data packets or
995 		 * when we do a gratuitous window update.
996 		 */
997 		if (((si->si_cc & SP_SP) == 0) || cb->s_force)
998 				si->si_cc |= SP_SA;
999 		si->si_seq = htons(si->si_seq);
1000 		si->si_alo = htons(alo);
1001 		si->si_ack = htons(cb->s_ack);
1002 
1003 		if (idpcksum) {
1004 			si->si_sum = 0;
1005 			len = ntohs(si->si_len);
1006 			if (len & 1)
1007 				len++;
1008 			si->si_sum = ns_cksum(dtom(si), len);
1009 		} else
1010 			si->si_sum = 0xffff;
1011 
1012 		cb->s_outx = 4;
1013 		if (so->so_options & SO_DEBUG || traceallspps)
1014 			spp_trace(SA_OUTPUT, cb->s_state, cb, si, 0);
1015 
1016 		if (so->so_options & SO_DONTROUTE)
1017 			error = ns_output(m, (struct route *)0, NS_ROUTETOIF);
1018 		else
1019 			error = ns_output(m, &cb->s_nspcb->nsp_route, 0);
1020 	}
1021 	if (error) {
1022 		return (error);
1023 	}
1024 	sppstat.spps_sndtotal++;
1025 	/*
1026 	 * Data sent (as far as we can tell).
1027 	 * If this advertises a larger window than any other segment,
1028 	 * then remember the size of the advertized window.
1029 	 * Any pending ACK has now been sent.
1030 	 */
1031 	cb->s_force = 0;
1032 	cb->s_flags &= ~(SF_ACKNOW|SF_DELACK);
1033 	if (SSEQ_GT(alo, cb->s_alo))
1034 		cb->s_alo = alo;
1035 	if (sendalot)
1036 		goto again;
1037 	cb->s_outx = 5;
1038 	return (0);
1039 }
1040 
1041 int spp_do_persist_panics = 0;
1042 
1043 spp_setpersist(cb)
1044 	register struct sppcb *cb;
1045 {
1046 	register t = ((cb->s_srtt >> 2) + cb->s_rttvar) >> 1;
1047 	extern int spp_backoff[];
1048 
1049 	if (cb->s_timer[SPPT_REXMT] && spp_do_persist_panics)
1050 		panic("spp_output REXMT");
1051 	/*
1052 	 * Start/restart persistance timer.
1053 	 */
1054 	SPPT_RANGESET(cb->s_timer[SPPT_PERSIST],
1055 	    t*spp_backoff[cb->s_rxtshift],
1056 	    SPPTV_PERSMIN, SPPTV_PERSMAX);
1057 	if (cb->s_rxtshift < SPP_MAXRXTSHIFT)
1058 		cb->s_rxtshift++;
1059 }
1060 /*ARGSUSED*/
1061 spp_ctloutput(req, so, level, name, value)
1062 	int req;
1063 	struct socket *so;
1064 	int name;
1065 	struct mbuf **value;
1066 {
1067 	register struct mbuf *m;
1068 	struct nspcb *nsp = sotonspcb(so);
1069 	register struct sppcb *cb;
1070 	int mask, error = 0;
1071 
1072 	if (level != NSPROTO_SPP) {
1073 		/* This will have to be changed when we do more general
1074 		   stacking of protocols */
1075 		return (idp_ctloutput(req, so, level, name, value));
1076 	}
1077 	if (nsp == NULL) {
1078 		error = EINVAL;
1079 		goto release;
1080 	} else
1081 		cb = nstosppcb(nsp);
1082 
1083 	switch (req) {
1084 
1085 	case PRCO_GETOPT:
1086 		if (value == NULL)
1087 			return (EINVAL);
1088 		m = m_get(M_DONTWAIT, MT_DATA);
1089 		if (m == NULL)
1090 			return (ENOBUFS);
1091 		switch (name) {
1092 
1093 		case SO_HEADERS_ON_INPUT:
1094 			mask = SF_HI;
1095 			goto get_flags;
1096 
1097 		case SO_HEADERS_ON_OUTPUT:
1098 			mask = SF_HO;
1099 		get_flags:
1100 			m->m_len = sizeof(short);
1101 			m->m_off = MMAXOFF - sizeof(short);
1102 			*mtod(m, short *) = cb->s_flags & mask;
1103 			break;
1104 
1105 		case SO_MTU:
1106 			m->m_len = sizeof(u_short);
1107 			m->m_off = MMAXOFF - sizeof(short);
1108 			*mtod(m, short *) = cb->s_mtu;
1109 			break;
1110 
1111 		case SO_LAST_HEADER:
1112 			m->m_len = sizeof(struct sphdr);
1113 			m->m_off = MMAXOFF - sizeof(struct sphdr);
1114 			*mtod(m, struct sphdr *) = cb->s_rhdr;
1115 			break;
1116 
1117 		case SO_DEFAULT_HEADERS:
1118 			m->m_len = sizeof(struct spidp);
1119 			m->m_off = MMAXOFF - sizeof(struct sphdr);
1120 			*mtod(m, struct sphdr *) = cb->s_shdr;
1121 			break;
1122 
1123 		default:
1124 			error = EINVAL;
1125 		}
1126 		*value = m;
1127 		break;
1128 
1129 	case PRCO_SETOPT:
1130 		if (value == 0 || *value == 0) {
1131 			error = EINVAL;
1132 			break;
1133 		}
1134 		switch (name) {
1135 			int *ok;
1136 
1137 		case SO_HEADERS_ON_INPUT:
1138 			mask = SF_HI;
1139 			goto set_head;
1140 
1141 		case SO_HEADERS_ON_OUTPUT:
1142 			mask = SF_HO;
1143 		set_head:
1144 			if (cb->s_flags & SF_PI) {
1145 				ok = mtod(*value, int *);
1146 				if (*ok)
1147 					cb->s_flags |= mask;
1148 				else
1149 					cb->s_flags &= ~mask;
1150 			} else error = EINVAL;
1151 			break;
1152 
1153 		case SO_MTU:
1154 			cb->s_mtu = *(mtod(*value, u_short *));
1155 			break;
1156 
1157 		case SO_DEFAULT_HEADERS:
1158 			{
1159 				register struct sphdr *sp
1160 						= mtod(*value, struct sphdr *);
1161 				cb->s_dt = sp->sp_dt;
1162 				cb->s_cc = sp->sp_cc & SP_EM;
1163 			}
1164 			break;
1165 
1166 		default:
1167 			error = EINVAL;
1168 		}
1169 		m_freem(*value);
1170 		break;
1171 	}
1172 	release:
1173 		return (error);
1174 }
1175 
1176 /*ARGSUSED*/
1177 spp_usrreq(so, req, m, nam, rights)
1178 	struct socket *so;
1179 	int req;
1180 	struct mbuf *m, *nam, *rights;
1181 {
1182 	struct nspcb *nsp = sotonspcb(so);
1183 	register struct sppcb *cb;
1184 	int s = splnet();
1185 	int error = 0, ostate;
1186 	struct mbuf *mm;
1187 	register struct sockbuf *sb;
1188 
1189 	if (req == PRU_CONTROL)
1190                 return (ns_control(so, (int)m, (caddr_t)nam,
1191 			(struct ifnet *)rights));
1192 	if (rights && rights->m_len) {
1193 		error = EINVAL;
1194 		goto release;
1195 	}
1196 	if (nsp == NULL) {
1197 		if (req != PRU_ATTACH) {
1198 			error = EINVAL;
1199 			goto release;
1200 		}
1201 	} else
1202 		cb = nstosppcb(nsp);
1203 
1204 	ostate = cb ? cb->s_state : 0;
1205 
1206 	switch (req) {
1207 
1208 	case PRU_ATTACH:
1209 		if (nsp != NULL) {
1210 			error = EISCONN;
1211 			break;
1212 		}
1213 		error = ns_pcballoc(so, &nspcb);
1214 		if (error)
1215 			break;
1216 		if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
1217 			error = soreserve(so, (u_long) 3072, (u_long) 3072);
1218 			if (error)
1219 				break;
1220 		}
1221 		nsp = sotonspcb(so);
1222 
1223 		mm = m_getclr(M_DONTWAIT, MT_PCB);
1224 		sb = &so->so_snd;
1225 
1226 		if (mm == NULL) {
1227 			error = ENOBUFS;
1228 			break;
1229 		}
1230 		cb = mtod(mm, struct sppcb *);
1231 		mm = m_getclr(M_DONTWAIT, MT_HEADER);
1232 		if (mm == NULL) {
1233 			(void) m_free(dtom(m));
1234 			error = ENOBUFS;
1235 			break;
1236 		}
1237 		cb->s_idp = mtod(mm, struct idp *);
1238 		cb->s_state = TCPS_LISTEN;
1239 		cb->s_smax = -1;
1240 		cb->s_swl1 = -1;
1241 		cb->s_q.si_next = cb->s_q.si_prev = &cb->s_q;
1242 		cb->s_nspcb = nsp;
1243 		cb->s_mtu = 576 - sizeof (struct spidp);
1244 		cb->s_cwnd = sbspace(sb) * CUNIT / cb->s_mtu;
1245 		cb->s_ssthresh = cb->s_cwnd;
1246 		cb->s_cwmx = sb->sb_mbmax * CUNIT /
1247 				(2 * sizeof (struct spidp));
1248 		/* Above is recomputed when connecting to account
1249 		   for changed buffering or mtu's */
1250 		cb->s_rtt = SPPTV_SRTTBASE;
1251 		cb->s_rttvar = SPPTV_SRTTDFLT << 2;
1252 		SPPT_RANGESET(cb->s_rxtcur,
1253 		    ((SPPTV_SRTTBASE >> 2) + (SPPTV_SRTTDFLT << 2)) >> 1,
1254 		    SPPTV_MIN, SPPTV_REXMTMAX);
1255 		nsp->nsp_pcb = (caddr_t) cb;
1256 		break;
1257 
1258 	case PRU_DETACH:
1259 		if (nsp == NULL) {
1260 			error = ENOTCONN;
1261 			break;
1262 		}
1263 		if (cb->s_state > TCPS_LISTEN)
1264 			cb = spp_disconnect(cb);
1265 		else
1266 			cb = spp_close(cb);
1267 		break;
1268 
1269 	case PRU_BIND:
1270 		error = ns_pcbbind(nsp, nam);
1271 		break;
1272 
1273 	case PRU_LISTEN:
1274 		if (nsp->nsp_lport == 0)
1275 			error = ns_pcbbind(nsp, (struct mbuf *)0);
1276 		if (error == 0)
1277 			cb->s_state = TCPS_LISTEN;
1278 		break;
1279 
1280 	/*
1281 	 * Initiate connection to peer.
1282 	 * Enter SYN_SENT state, and mark socket as connecting.
1283 	 * Start keep-alive timer, setup prototype header,
1284 	 * Send initial system packet requesting connection.
1285 	 */
1286 	case PRU_CONNECT:
1287 		if (nsp->nsp_lport == 0) {
1288 			error = ns_pcbbind(nsp, (struct mbuf *)0);
1289 			if (error)
1290 				break;
1291 		}
1292 		error = ns_pcbconnect(nsp, nam);
1293 		if (error)
1294 			break;
1295 		soisconnecting(so);
1296 		sppstat.spps_connattempt++;
1297 		cb->s_state = TCPS_SYN_SENT;
1298 		cb->s_did = 0;
1299 		spp_template(cb);
1300 		cb->s_timer[SPPT_KEEP] = SPPTV_KEEP;
1301 		cb->s_force = 1 + SPPTV_KEEP;
1302 		/*
1303 		 * Other party is required to respond to
1304 		 * the port I send from, but he is not
1305 		 * required to answer from where I am sending to,
1306 		 * so allow wildcarding.
1307 		 * original port I am sending to is still saved in
1308 		 * cb->s_dport.
1309 		 */
1310 		nsp->nsp_fport = 0;
1311 		error = spp_output(cb, (struct mbuf *) 0);
1312 		break;
1313 
1314 	case PRU_CONNECT2:
1315 		error = EOPNOTSUPP;
1316 		break;
1317 
1318 	/*
1319 	 * We may decide later to implement connection closing
1320 	 * handshaking at the spp level optionally.
1321 	 * here is the hook to do it:
1322 	 */
1323 	case PRU_DISCONNECT:
1324 		cb = spp_disconnect(cb);
1325 		break;
1326 
1327 	/*
1328 	 * Accept a connection.  Essentially all the work is
1329 	 * done at higher levels; just return the address
1330 	 * of the peer, storing through addr.
1331 	 */
1332 	case PRU_ACCEPT: {
1333 		struct sockaddr_ns *sns = mtod(nam, struct sockaddr_ns *);
1334 
1335 		nam->m_len = sizeof (struct sockaddr_ns);
1336 		sns->sns_family = AF_NS;
1337 		sns->sns_addr = nsp->nsp_faddr;
1338 		break;
1339 		}
1340 
1341 	case PRU_SHUTDOWN:
1342 		socantsendmore(so);
1343 		cb = spp_usrclosed(cb);
1344 		if (cb)
1345 			error = spp_output(cb, (struct mbuf *) 0);
1346 		break;
1347 
1348 	/*
1349 	 * After a receive, possibly send acknowledgment
1350 	 * updating allocation.
1351 	 */
1352 	case PRU_RCVD:
1353 		cb->s_flags |= SF_RVD;
1354 		(void) spp_output(cb, (struct mbuf *) 0);
1355 		cb->s_flags &= ~SF_RVD;
1356 		break;
1357 
1358 	case PRU_ABORT:
1359 		(void) spp_drop(cb, ECONNABORTED);
1360 		break;
1361 
1362 	case PRU_SENSE:
1363 	case PRU_CONTROL:
1364 		m = NULL;
1365 		error = EOPNOTSUPP;
1366 		break;
1367 
1368 	case PRU_RCVOOB:
1369 		if ((cb->s_oobflags & SF_IOOB) || so->so_oobmark ||
1370 		    (so->so_state & SS_RCVATMARK)) {
1371 			m->m_len = 1;
1372 			*mtod(m, caddr_t) = cb->s_iobc;
1373 			break;
1374 		}
1375 		error = EINVAL;
1376 		break;
1377 
1378 	case PRU_SENDOOB:
1379 		if (sbspace(&so->so_snd) < -512) {
1380 			error = ENOBUFS;
1381 			break;
1382 		}
1383 		cb->s_oobflags |= SF_SOOB;
1384 		/* fall into */
1385 	case PRU_SEND:
1386 		error = spp_output(cb, m);
1387 		m = NULL;
1388 		break;
1389 
1390 	case PRU_SOCKADDR:
1391 		ns_setsockaddr(nsp, nam);
1392 		break;
1393 
1394 	case PRU_PEERADDR:
1395 		ns_setpeeraddr(nsp, nam);
1396 		break;
1397 
1398 	case PRU_SLOWTIMO:
1399 		cb = spp_timers(cb, (int)nam);
1400 		req |= ((int)nam) << 8;
1401 		break;
1402 
1403 	case PRU_FASTTIMO:
1404 	case PRU_PROTORCV:
1405 	case PRU_PROTOSEND:
1406 		error =  EOPNOTSUPP;
1407 		break;
1408 
1409 	default:
1410 		panic("sp_usrreq");
1411 	}
1412 	if (cb && (so->so_options & SO_DEBUG || traceallspps))
1413 		spp_trace(SA_USER, (u_char)ostate, cb, (struct spidp *)0, req);
1414 release:
1415 	if (m != NULL)
1416 		m_freem(m);
1417 	splx(s);
1418 	return (error);
1419 }
1420 
1421 spp_usrreq_sp(so, req, m, nam, rights)
1422 	struct socket *so;
1423 	int req;
1424 	struct mbuf *m, *nam, *rights;
1425 {
1426 	int error = spp_usrreq(so, req, m, nam, rights);
1427 
1428 	if (req == PRU_ATTACH && error == 0) {
1429 		struct nspcb *nsp = sotonspcb(so);
1430 		((struct sppcb *)nsp->nsp_pcb)->s_flags |=
1431 					(SF_HI | SF_HO | SF_PI);
1432 	}
1433 	return (error);
1434 }
1435 
1436 /*
1437  * Create template to be used to send spp packets on a connection.
1438  * Called after host entry created, fills
1439  * in a skeletal spp header (choosing connection id),
1440  * minimizing the amount of work necessary when the connection is used.
1441  */
1442 spp_template(cb)
1443 	register struct sppcb *cb;
1444 {
1445 	register struct nspcb *nsp = cb->s_nspcb;
1446 	register struct idp *idp = cb->s_idp;
1447 	register struct sockbuf *sb = &(nsp->nsp_socket->so_snd);
1448 
1449 	idp->idp_pt = NSPROTO_SPP;
1450 	idp->idp_sna = nsp->nsp_laddr;
1451 	idp->idp_dna = nsp->nsp_faddr;
1452 	cb->s_sid = htons(spp_iss);
1453 	spp_iss += SPP_ISSINCR/2;
1454 	cb->s_alo = 1;
1455 	cb->s_cwnd = (sbspace(sb) * CUNIT) / cb->s_mtu;
1456 	cb->s_ssthresh = cb->s_cwnd; /* Try to expand fast to full complement
1457 					of large packets */
1458 	cb->s_cwmx = (sb->sb_mbmax * CUNIT) / (2 * sizeof(struct spidp));
1459 	cb->s_cwmx = MAX(cb->s_cwmx, cb->s_cwnd);
1460 		/* But allow for lots of little packets as well */
1461 }
1462 
1463 /*
1464  * Close a SPIP control block:
1465  *	discard spp control block itself
1466  *	discard ns protocol control block
1467  *	wake up any sleepers
1468  */
1469 struct sppcb *
1470 spp_close(cb)
1471 	register struct sppcb *cb;
1472 {
1473 	register struct spidp_q *s;
1474 	struct nspcb *nsp = cb->s_nspcb;
1475 	struct socket *so = nsp->nsp_socket;
1476 	register struct mbuf *m;
1477 
1478 	s = cb->s_q.si_next;
1479 	while (s != &(cb->s_q)) {
1480 		s = s->si_next;
1481 		m = dtom(s->si_prev);
1482 		remque(s->si_prev);
1483 		m_freem(m);
1484 	}
1485 	(void) m_free(dtom(cb->s_idp));
1486 	(void) m_free(dtom(cb));
1487 	nsp->nsp_pcb = 0;
1488 	soisdisconnected(so);
1489 	ns_pcbdetach(nsp);
1490 	sppstat.spps_closed++;
1491 	return ((struct sppcb *)0);
1492 }
1493 /*
1494  *	Someday we may do level 3 handshaking
1495  *	to close a connection or send a xerox style error.
1496  *	For now, just close.
1497  */
1498 struct sppcb *
1499 spp_usrclosed(cb)
1500 	register struct sppcb *cb;
1501 {
1502 	return (spp_close(cb));
1503 }
1504 struct sppcb *
1505 spp_disconnect(cb)
1506 	register struct sppcb *cb;
1507 {
1508 	return (spp_close(cb));
1509 }
1510 /*
1511  * Drop connection, reporting
1512  * the specified error.
1513  */
1514 struct sppcb *
1515 spp_drop(cb, errno)
1516 	register struct sppcb *cb;
1517 	int errno;
1518 {
1519 	struct socket *so = cb->s_nspcb->nsp_socket;
1520 
1521 	/*
1522 	 * someday, in the xerox world
1523 	 * we will generate error protocol packets
1524 	 * announcing that the socket has gone away.
1525 	 */
1526 	if (TCPS_HAVERCVDSYN(cb->s_state)) {
1527 		sppstat.spps_drops++;
1528 		cb->s_state = TCPS_CLOSED;
1529 		/*(void) tcp_output(cb);*/
1530 	} else
1531 		sppstat.spps_conndrops++;
1532 	so->so_error = errno;
1533 	return (spp_close(cb));
1534 }
1535 
1536 spp_abort(nsp)
1537 	struct nspcb *nsp;
1538 {
1539 
1540 	(void) spp_close((struct sppcb *)nsp->nsp_pcb);
1541 }
1542 
1543 int	spp_backoff[SPP_MAXRXTSHIFT+1] =
1544     { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
1545 /*
1546  * Fast timeout routine for processing delayed acks
1547  */
1548 spp_fasttimo()
1549 {
1550 	register struct nspcb *nsp;
1551 	register struct sppcb *cb;
1552 	int s = splnet();
1553 
1554 	nsp = nspcb.nsp_next;
1555 	if (nsp)
1556 	for (; nsp != &nspcb; nsp = nsp->nsp_next)
1557 		if ((cb = (struct sppcb *)nsp->nsp_pcb) &&
1558 		    (cb->s_flags & SF_DELACK)) {
1559 			cb->s_flags &= ~SF_DELACK;
1560 			cb->s_flags |= SF_ACKNOW;
1561 			sppstat.spps_delack++;
1562 			(void) spp_output(cb, (struct mbuf *) 0);
1563 		}
1564 	splx(s);
1565 }
1566 
1567 /*
1568  * spp protocol timeout routine called every 500 ms.
1569  * Updates the timers in all active pcb's and
1570  * causes finite state machine actions if timers expire.
1571  */
1572 spp_slowtimo()
1573 {
1574 	register struct nspcb *ip, *ipnxt;
1575 	register struct sppcb *cb;
1576 	int s = splnet();
1577 	register int i;
1578 
1579 	/*
1580 	 * Search through tcb's and update active timers.
1581 	 */
1582 	ip = nspcb.nsp_next;
1583 	if (ip == 0) {
1584 		splx(s);
1585 		return;
1586 	}
1587 	while (ip != &nspcb) {
1588 		cb = nstosppcb(ip);
1589 		ipnxt = ip->nsp_next;
1590 		if (cb == 0)
1591 			goto tpgone;
1592 		for (i = 0; i < SPPT_NTIMERS; i++) {
1593 			if (cb->s_timer[i] && --cb->s_timer[i] == 0) {
1594 				(void) spp_usrreq(cb->s_nspcb->nsp_socket,
1595 				    PRU_SLOWTIMO, (struct mbuf *)0,
1596 				    (struct mbuf *)i, (struct mbuf *)0);
1597 				if (ipnxt->nsp_prev != ip)
1598 					goto tpgone;
1599 			}
1600 		}
1601 		cb->s_idle++;
1602 		if (cb->s_rtt)
1603 			cb->s_rtt++;
1604 tpgone:
1605 		ip = ipnxt;
1606 	}
1607 	spp_iss += SPP_ISSINCR/PR_SLOWHZ;		/* increment iss */
1608 	splx(s);
1609 }
1610 /*
1611  * SPP timer processing.
1612  */
1613 struct sppcb *
1614 spp_timers(cb, timer)
1615 	register struct sppcb *cb;
1616 	int timer;
1617 {
1618 	long rexmt;
1619 	int win;
1620 
1621 	cb->s_force = 1 + timer;
1622 	switch (timer) {
1623 
1624 	/*
1625 	 * 2 MSL timeout in shutdown went off.  TCP deletes connection
1626 	 * control block.
1627 	 */
1628 	case SPPT_2MSL:
1629 		printf("spp: SPPT_2MSL went off for no reason\n");
1630 		cb->s_timer[timer] = 0;
1631 		break;
1632 
1633 	/*
1634 	 * Retransmission timer went off.  Message has not
1635 	 * been acked within retransmit interval.  Back off
1636 	 * to a longer retransmit interval and retransmit one packet.
1637 	 */
1638 	case SPPT_REXMT:
1639 		if (++cb->s_rxtshift > SPP_MAXRXTSHIFT) {
1640 			cb->s_rxtshift = SPP_MAXRXTSHIFT;
1641 			sppstat.spps_timeoutdrop++;
1642 			cb = spp_drop(cb, ETIMEDOUT);
1643 			break;
1644 		}
1645 		sppstat.spps_rexmttimeo++;
1646 		rexmt = ((cb->s_srtt >> 2) + cb->s_rttvar) >> 1;
1647 		rexmt *= spp_backoff[cb->s_rxtshift];
1648 		SPPT_RANGESET(cb->s_rxtcur, rexmt, SPPTV_MIN, SPPTV_REXMTMAX);
1649 		cb->s_timer[SPPT_REXMT] = cb->s_rxtcur;
1650 		/*
1651 		 * If we have backed off fairly far, our srtt
1652 		 * estimate is probably bogus.  Clobber it
1653 		 * so we'll take the next rtt measurement as our srtt;
1654 		 * move the current srtt into rttvar to keep the current
1655 		 * retransmit times until then.
1656 		 */
1657 		if (cb->s_rxtshift > SPP_MAXRXTSHIFT / 4 ) {
1658 			cb->s_rttvar += (cb->s_srtt >> 2);
1659 			cb->s_srtt = 0;
1660 		}
1661 		cb->s_snxt = cb->s_rack;
1662 		/*
1663 		 * If timing a packet, stop the timer.
1664 		 */
1665 		cb->s_rtt = 0;
1666 		/*
1667 		 * See very long discussion in tcp_timer.c about congestion
1668 		 * window and sstrhesh
1669 		 */
1670 		win = MIN(cb->s_swnd, (cb->s_cwnd/CUNIT)) / 2;
1671 		if (win < 2)
1672 			win = 2;
1673 		cb->s_cwnd = CUNIT;
1674 		cb->s_ssthresh = win * CUNIT;
1675 		(void) spp_output(cb, (struct mbuf *) 0);
1676 		break;
1677 
1678 	/*
1679 	 * Persistance timer into zero window.
1680 	 * Force a probe to be sent.
1681 	 */
1682 	case SPPT_PERSIST:
1683 		sppstat.spps_persisttimeo++;
1684 		spp_setpersist(cb);
1685 		(void) spp_output(cb, (struct mbuf *) 0);
1686 		break;
1687 
1688 	/*
1689 	 * Keep-alive timer went off; send something
1690 	 * or drop connection if idle for too long.
1691 	 */
1692 	case SPPT_KEEP:
1693 		sppstat.spps_keeptimeo++;
1694 		if (cb->s_state < TCPS_ESTABLISHED)
1695 			goto dropit;
1696 		if (cb->s_nspcb->nsp_socket->so_options & SO_KEEPALIVE) {
1697 		    	if (cb->s_idle >= SPPTV_MAXIDLE)
1698 				goto dropit;
1699 			sppstat.spps_keepprobe++;
1700 			(void) spp_output(cb, (struct mbuf *) 0);
1701 		} else
1702 			cb->s_idle = 0;
1703 		cb->s_timer[SPPT_KEEP] = SPPTV_KEEP;
1704 		break;
1705 	dropit:
1706 		sppstat.spps_keepdrops++;
1707 		cb = spp_drop(cb, ETIMEDOUT);
1708 		break;
1709 	}
1710 	return (cb);
1711 }
1712 #ifndef lint
1713 int SppcbSize = sizeof (struct sppcb);
1714 int NspcbSize = sizeof (struct nspcb);
1715 #endif lint
1716