xref: /csrg-svn/sys/deprecated/netimp/if_imp.c (revision 23166)
1 /*
2  * Copyright (c) 1982 Regents of the University of California.
3  * All rights reserved.  The Berkeley software License Agreement
4  * specifies the terms and conditions for redistribution.
5  *
6  *	@(#)if_imp.c	6.6 (Berkeley) 06/08/85
7  */
8 
9 #include "imp.h"
10 #if NIMP > 0
11 /*
12  * ARPANET IMP interface driver.
13  *
14  * The IMP-host protocol is handled here, leaving
15  * hardware specifics to the lower level interface driver.
16  */
17 #include "../machine/pte.h"
18 
19 #include "param.h"
20 #include "systm.h"
21 #include "mbuf.h"
22 #include "buf.h"
23 #include "protosw.h"
24 #include "socket.h"
25 #include "vmmac.h"
26 #include "time.h"
27 #include "kernel.h"
28 #include "errno.h"
29 #include "ioctl.h"
30 
31 #include "../vax/cpu.h"
32 #include "../vax/mtpr.h"
33 #include "../vaxuba/ubareg.h"
34 #include "../vaxuba/ubavar.h"
35 
36 #include "../net/if.h"
37 #include "../net/route.h"
38 
39 #include "../net/netisr.h"
40 #include "../netinet/in.h"
41 #include "../netinet/in_systm.h"
42 #include "../netinet/in_var.h"
43 #include "../netinet/ip.h"
44 #include "../netinet/ip_var.h"
45 /* define IMPLEADERS here to get leader printing code */
46 #include "if_imp.h"
47 #include "if_imphost.h"
48 
49 /*
50  * IMP software status per interface.
51  * (partially shared with the hardware specific module)
52  *
53  * Each interface is referenced by a network interface structure,
54  * imp_if, which the routing code uses to locate the interface.
55  * This structure contains the output queue for the interface, its
56  * address, ...  IMP specific structures used in connecting the
57  * IMP software modules to the hardware specific interface routines
58  * are stored here.  The common structures are made visible to the
59  * interface driver by passing a pointer to the hardware routine
60  * at "attach" time.
61  *
62  * NOTE: imp_if and imp_cb are assumed adjacent in hardware code.
63  */
64 struct imp_softc {
65 	struct	ifnet imp_if;		/* network visible interface */
66 	struct	impcb imp_cb;		/* hooks to hardware module */
67 	u_char	imp_state;		/* current state of IMP */
68 	char	imp_dropcnt;		/* used during initialization */
69 } imp_softc[NIMP];
70 
71 /*
72  * Messages from IMP regarding why
73  * it's going down.
74  */
75 static char *impmessage[] = {
76 	"in 30 seconds",
77 	"for hardware PM",
78 	"to reload software",
79 	"for emergency reset"
80 };
81 
82 #define HOSTDEADTIMER	10		/* How long to wait when down */
83 
84 int	impdown(), impinit(), impioctl(), impoutput();
85 
86 /*
87  * IMP attach routine.  Called from hardware device attach routine
88  * at configuration time with a pointer to the UNIBUS device structure.
89  * Sets up local state and returns pointer to base of ifnet+impcb
90  * structures.  This is then used by the device's attach routine
91  * set up its back pointers.
92  */
93 impattach(ui, reset)
94 	struct uba_device *ui;
95 	int (*reset)();
96 {
97 	struct imp_softc *sc = &imp_softc[ui->ui_unit];
98 	register struct ifnet *ifp = &sc->imp_if;
99 
100 	/* UNIT COULD BE AMBIGUOUS */
101 	ifp->if_unit = ui->ui_unit;
102 	ifp->if_name = "imp";
103 	ifp->if_mtu = IMPMTU - sizeof(struct imp_leader);
104 	ifp->if_reset = reset;
105 	ifp->if_init = impinit;
106 	ifp->if_ioctl = impioctl;
107 	ifp->if_output = impoutput;
108 	/* reset is handled at the hardware level */
109 	if_attach(ifp);
110 	return ((int)&sc->imp_if);
111 }
112 
113 /*
114  * IMP initialization routine: call hardware module to
115  * setup UNIBUS resources, init state and get ready for
116  * NOOPs the IMP should send us, and that we want to drop.
117  */
118 impinit(unit)
119 	int unit;
120 {
121 	int s = splimp();
122 	register struct imp_softc *sc = &imp_softc[unit];
123 
124 	if (sc->imp_if.if_addrlist == 0)
125 		return;
126 	if ((*sc->imp_cb.ic_init)(unit) == 0) {
127 		sc->imp_state = IMPS_DOWN;
128 		sc->imp_if.if_flags &= ~IFF_UP;
129 		splx(s);
130 		return;
131 	}
132 	sc->imp_state = IMPS_INIT;
133 	impnoops(sc);
134 	splx(s);
135 }
136 
137 struct sockproto impproto = { PF_IMPLINK };
138 struct sockaddr_in impdst = { AF_IMPLINK };
139 struct sockaddr_in impsrc = { AF_IMPLINK };
140 #ifdef IMPLEADERS
141 int	impprintfs = 0;
142 #endif
143 
144 /*
145  * ARPAnet 1822 input routine.
146  * Called from hardware input interrupt routine to handle 1822
147  * IMP-host messages.  Type 0 messages (non-control) are
148  * passed to higher level protocol processors on the basis
149  * of link number.  Other type messages (control) are handled here.
150  */
151 impinput(unit, m)
152 	int unit;
153 	register struct mbuf *m;
154 {
155 	register struct imp_leader *ip;
156 	register struct imp_softc *sc = &imp_softc[unit];
157 	register struct host *hp;
158 	register struct ifqueue *inq;
159 	struct control_leader *cp;
160 	struct in_addr addr;
161 	struct mbuf *next;
162 	struct sockaddr_in *sin;
163 
164 	/* verify leader length. */
165 	if (m->m_len < sizeof(struct control_leader) &&
166 	    (m = m_pullup(m, sizeof(struct control_leader))) == 0)
167 		return;
168 	cp = mtod(m, struct control_leader *);
169 	if (cp->dl_mtype == IMPTYPE_DATA)
170 		if (m->m_len < sizeof(struct imp_leader) &&
171 		    (m = m_pullup(m, sizeof(struct imp_leader))) == 0)
172 			return;
173 	ip = mtod(m, struct imp_leader *);
174 #ifdef IMPLEADERS
175 	if (impprintfs)
176 		printleader("impinput", ip);
177 #endif
178 
179 	/* check leader type */
180 	if (ip->il_format != IMP_NFF) {
181 		sc->imp_if.if_collisions++;	/* XXX */
182 		goto drop;
183 	}
184 
185 	if (ip->il_mtype != IMPTYPE_DATA) {
186 		/* If not data packet, build IP addr from leader (BRL) */
187 		imp_leader_to_addr(&addr, ip, &sc->imp_if);
188 	}
189 	switch (ip->il_mtype) {
190 
191 	case IMPTYPE_DATA:
192 		break;
193 
194 	/*
195 	 * IMP leader error.  Reset the IMP and discard the packet.
196 	 */
197 	case IMPTYPE_BADLEADER:
198 		/*
199 		 * According to 1822 document, this message
200 		 * will be generated in response to the
201 		 * first noop sent to the IMP after
202 		 * the host resets the IMP interface.
203 		 */
204 		if (sc->imp_state != IMPS_INIT) {
205 			impmsg(sc, "leader error");
206 			hostreset(((struct in_ifaddr *)&sc->imp_if.if_addrlist)->ia_net);
207 			impnoops(sc);
208 		}
209 		goto drop;
210 
211 	/*
212 	 * IMP going down.  Print message, and if not immediate,
213 	 * set off a timer to insure things will be reset at the
214 	 * appropriate time.
215 	 */
216 	case IMPTYPE_DOWN:
217 		if (sc->imp_state < IMPS_INIT)
218 			goto drop;
219 		if ((ip->il_link & IMP_DMASK) == 0) {
220 			sc->imp_state = IMPS_GOINGDOWN;
221 			timeout(impdown, (caddr_t)sc, 30 * hz);
222 		}
223 		impmsg(sc, "going down %s",
224 			(u_int)impmessage[ip->il_link&IMP_DMASK]);
225 		goto drop;
226 
227 	/*
228 	 * A NOP usually seen during the initialization sequence.
229 	 * Compare the local address with that in the message.
230 	 * Reset the local address notion if it doesn't match.
231 	 */
232 	case IMPTYPE_NOOP:
233 		if (sc->imp_state == IMPS_DOWN) {
234 			sc->imp_state = IMPS_INIT;
235 			sc->imp_dropcnt = IMP_DROPCNT;
236 		}
237 		if (sc->imp_state == IMPS_INIT && --sc->imp_dropcnt > 0)
238 			goto drop;
239 		sin = (struct sockaddr_in *)&sc->imp_if.if_addrlist->ifa_addr;
240 		if (ip->il_imp != 0) {	/* BRL */
241 			struct in_addr leader_addr;
242 			imp_leader_to_addr(&leader_addr, ip, &sc->imp_if);
243 			if (sin->sin_addr.s_addr != leader_addr.s_addr) {
244 				impmsg(sc, "address reset to x%x (%d/%d)",
245 					htonl(leader_addr.s_addr),
246 					(u_int)ip->il_host,
247 					htons(ip->il_imp));
248 				sin->sin_addr.s_addr = leader_addr.s_addr;
249 			}
250 		}
251 		sc->imp_state = IMPS_UP;
252 		sc->imp_if.if_flags |= IFF_UP;
253 		goto drop;
254 
255 	/*
256 	 * RFNM or INCOMPLETE message, send next
257 	 * message on the q.  We could pass incomplete's
258 	 * up to the next level, but this currently isn't
259 	 * needed.
260 	 */
261 	case IMPTYPE_RFNM:
262 	case IMPTYPE_INCOMPLETE:
263 		if (hp = hostlookup(addr)) {
264 			if (hp->h_rfnm == 0)
265 				hp->h_flags &= ~HF_INUSE;
266 			else if (next = hostdeque(hp))
267 				(void) impsnd(&sc->imp_if, next);
268 		}
269 		goto drop;
270 
271 	/*
272 	 * Host or IMP can't be reached.  Flush any packets
273 	 * awaiting transmission and release the host structure.
274 	 */
275 	case IMPTYPE_HOSTDEAD:
276 	case IMPTYPE_HOSTUNREACH:
277 		impnotify((int)ip->il_mtype, (struct control_leader *)ip,
278 		    hostlookup(addr), &sc->imp_if);
279 		goto rawlinkin;
280 
281 	/*
282 	 * Error in data.  Clear RFNM status for this host and send
283 	 * noops to the IMP to clear the interface.
284 	 */
285 	case IMPTYPE_BADDATA:
286 		impmsg(sc, "data error");
287 		if (hp = hostlookup(addr))
288 			hp->h_rfnm = 0;
289 		impnoops(sc);
290 		goto drop;
291 
292 	/*
293 	 * Interface reset.
294 	 */
295 	case IMPTYPE_RESET:
296 		impmsg(sc, "interface reset");
297 		/* clear RFNM counts */
298 		hostreset(((struct in_ifaddr *)&sc->imp_if.if_addrlist)->ia_net);
299 		impnoops(sc);
300 		goto drop;
301 
302 	default:
303 		sc->imp_if.if_collisions++;		/* XXX */
304 		goto drop;
305 	}
306 
307 	/*
308 	 * Data for a protocol.  Dispatch to the appropriate
309 	 * protocol routine (running at software interrupt).
310 	 * If this isn't a raw interface, advance pointer
311 	 * into mbuf past leader.
312 	 */
313 	switch (ip->il_link) {
314 
315 #ifdef INET
316 	case IMPLINK_IP:
317 		m->m_len -= sizeof(struct imp_leader);
318 		m->m_off += sizeof(struct imp_leader);
319 		schednetisr(NETISR_IP);
320 		inq = &ipintrq;
321 		break;
322 #endif
323 
324 	default:
325 	rawlinkin:
326 		impproto.sp_protocol = ip->il_link;
327 		sin = (struct sockaddr_in *)&sc->imp_if.if_addrlist->ifa_addr;
328 		impdst.sin_addr = sin->sin_addr;
329 		imp_leader_to_addr(&impsrc.sin_addr, ip, &sc->imp_if);
330 		raw_input(m, &impproto, (struct sockaddr *)&impsrc,
331 		  (struct sockaddr *)&impdst);
332 		return;
333 	}
334 	if (IF_QFULL(inq)) {
335 		IF_DROP(inq);
336 		goto drop;
337 	}
338 	IF_ENQUEUE(inq, m);
339 	return;
340 
341 drop:
342 	m_freem(m);
343 }
344 
345 /*
346  * Bring the IMP down after notification.
347  */
348 impdown(sc)
349 	struct imp_softc *sc;
350 {
351 	int s = splimp();
352 
353 	sc->imp_state = IMPS_DOWN;
354 	impmsg(sc, "marked down");
355 	hostreset(((struct in_ifaddr *)&sc->imp_if.if_addrlist)->ia_net);
356 	if_down(&sc->imp_if);
357 	splx(s);
358 }
359 
360 /*VARARGS*/
361 impmsg(sc, fmt, a1, a2, a3)
362 	struct imp_softc *sc;
363 	char *fmt;
364 	u_int a1;
365 {
366 
367 	printf("imp%d: ", sc->imp_if.if_unit);
368 	printf(fmt, a1, a2, a3);
369 	printf("\n");
370 }
371 
372 /*
373  * Process an IMP "error" message, passing this
374  * up to the higher level protocol.
375  */
376 impnotify(what, cp, hp, ifp)
377 	int what;
378 	struct control_leader *cp;
379 	struct host *hp;
380 	struct ifnet *ifp;		/* BRL */
381 {
382 	struct in_addr in;
383 
384 	imp_leader_to_addr(&in, (struct imp_leader *)cp, ifp);  /* BRL */
385 
386 	if (cp->dl_link != IMPLINK_IP)
387 		raw_ctlinput(what, (caddr_t)&in);
388 	else
389 		pfctlinput(what, (caddr_t)&in);
390 	if (hp) {
391 		hp->h_flags |= (1 << what);
392 		hostfree(hp);
393 		hp->h_timer = HOSTDEADTIMER;
394 	}
395 }
396 
397 /*
398  * ARPAnet 1822 output routine.
399  * Called from higher level protocol routines to set up messages for
400  * transmission to the imp.  Sets up the header and calls impsnd to
401  * enqueue the message for this IMP's hardware driver.
402  */
403 impoutput(ifp, m0, dst)
404 	register struct ifnet *ifp;
405 	struct mbuf *m0;
406 	struct sockaddr *dst;
407 {
408 	register struct imp_leader *imp;
409 	register struct mbuf *m = m0;
410 	int dlink, len;
411 	int error = 0;
412 
413 	/*
414 	 * Don't even try if the IMP is unavailable.
415 	 */
416 	if (imp_softc[ifp->if_unit].imp_state != IMPS_UP) {
417 		error = ENETDOWN;
418 		goto drop;
419 	}
420 
421 	switch (dst->sa_family) {
422 
423 #ifdef INET
424 	case AF_INET: {
425 		struct ip *ip = mtod(m0, struct ip *);
426 		struct sockaddr_in *sin = (struct sockaddr_in *)dst;
427 
428 		dlink = IMPLINK_IP;
429 		len = ntohs((u_short)ip->ip_len);
430 		break;
431 	}
432 #endif
433 	case AF_IMPLINK:
434 		goto leaderexists;
435 
436 	default:
437 		printf("imp%d: can't handle af%d\n", ifp->if_unit,
438 			dst->sa_family);
439 		error = EAFNOSUPPORT;
440 		goto drop;
441 	}
442 
443 	/*
444 	 * Add IMP leader.  If there's not enough space in the
445 	 * first mbuf, allocate another.  If that should fail, we
446 	 * drop this sucker.
447 	 */
448 	if (m->m_off > MMAXOFF ||
449 	    MMINOFF + sizeof(struct imp_leader) > m->m_off) {
450 		m = m_get(M_DONTWAIT, MT_HEADER);
451 		if (m == 0) {
452 			error = ENOBUFS;
453 			goto drop;
454 		}
455 		m->m_next = m0;
456 		m->m_len = sizeof(struct imp_leader);
457 	} else {
458 		m->m_off -= sizeof(struct imp_leader);
459 		m->m_len += sizeof(struct imp_leader);
460 	}
461 	imp = mtod(m, struct imp_leader *);
462 	imp->il_format = IMP_NFF;
463 	imp->il_mtype = IMPTYPE_DATA;
464 	imp_addr_to_leader(imp,
465 		((struct sockaddr_in *)dst)->sin_addr.s_addr); /* BRL */
466 	imp->il_length = htons((u_short)len << 3);		/* BRL */
467 	imp->il_link = dlink;
468 	imp->il_flags = imp->il_htype = imp->il_subtype = 0;
469 
470 leaderexists:
471 	return (impsnd(ifp, m));
472 drop:
473 	m_freem(m0);
474 	return (error);
475 }
476 
477 /*
478  * Put a message on an interface's output queue.
479  * Perform RFNM counting: no more than 8 message may be
480  * in flight to any one host.
481  */
482 impsnd(ifp, m)
483 	struct ifnet *ifp;
484 	struct mbuf *m;
485 {
486 	register struct imp_leader *ip;
487 	register struct host *hp;
488 	struct impcb *icp;
489 	int s, error;
490 
491 	ip = mtod(m, struct imp_leader *);
492 
493 	/*
494 	 * Do RFNM counting for data messages
495 	 * (no more than 8 outstanding to any host)
496 	 */
497 	s = splimp();
498 	if (ip->il_mtype == IMPTYPE_DATA) {
499 		struct in_addr addr;
500 
501 		imp_leader_to_addr(&addr, ip, ifp);	/* BRL */
502 		if ((hp = hostlookup(addr)) == 0)
503 			hp = hostenter(addr);
504 		if (hp && (hp->h_flags & (HF_DEAD|HF_UNREACH))) {
505 			error = hp->h_flags&HF_DEAD ? EHOSTDOWN : EHOSTUNREACH;
506 			hp->h_timer = HOSTDEADTIMER;
507 			hp->h_flags &= ~HF_INUSE;
508 			goto bad;
509 		}
510 
511 		/*
512 		 * If IMP would block, queue until RFNM
513 		 */
514 		if (hp) {
515 #ifndef NORFNM					/* BRL */
516 			if (hp->h_rfnm < 8)
517 #endif
518 			{
519 				hp->h_rfnm++;
520 				goto enque;
521 			}
522 			if (hp->h_qcnt < 8) {	/* high water mark */
523 				HOST_ENQUE(hp, m);
524 				goto start;
525 			}
526 		}
527 		error = ENOBUFS;
528 		goto bad;
529 	}
530 enque:
531 	if (IF_QFULL(&ifp->if_snd)) {
532 		IF_DROP(&ifp->if_snd);
533 		error = ENOBUFS;
534 bad:
535 		m_freem(m);
536 		splx(s);
537 		return (error);
538 	}
539 	IF_ENQUEUE(&ifp->if_snd, m);
540 start:
541 	icp = &imp_softc[ifp->if_unit].imp_cb;
542 	if (icp->ic_oactive == 0)
543 		(*icp->ic_start)(ifp->if_unit);
544 	splx(s);
545 	return (0);
546 }
547 
548 /*
549  * Put three 1822 NOOPs at the head of the output queue.
550  * Part of host-IMP initialization procedure.
551  * (Should return success/failure, but noone knows
552  * what to do with this, so why bother?)
553  * This routine is always called at splimp, so we don't
554  * protect the call to IF_PREPEND.
555  */
556 impnoops(sc)
557 	register struct imp_softc *sc;
558 {
559 	register i;
560 	register struct mbuf *m;
561 	register struct control_leader *cp;
562 
563 	sc->imp_dropcnt = IMP_DROPCNT;
564 	for (i = 0; i < IMP_DROPCNT + 1; i++) {
565 		if ((m = m_getclr(M_DONTWAIT, MT_HEADER)) == 0)
566 			return;
567 		m->m_len = sizeof(struct control_leader);
568 		cp = mtod(m, struct control_leader *);
569 		cp->dl_format = IMP_NFF;
570                 cp->dl_link = i;
571                 cp->dl_mtype = IMPTYPE_NOOP;
572 		IF_PREPEND(&sc->imp_if.if_snd, m);
573 	}
574 	if (sc->imp_cb.ic_oactive == 0)
575 		(*sc->imp_cb.ic_start)(sc->imp_if.if_unit);
576 }
577 
578 /*
579  * Process an ioctl request.
580  */
581 impioctl(ifp, cmd, data)
582 	register struct ifnet *ifp;
583 	int cmd;
584 	caddr_t data;
585 {
586 	struct ifaddr *ifa = (struct ifaddr *) data;
587 	int s = splimp(), error = 0;
588 
589 	switch (cmd) {
590 
591 	case SIOCSIFADDR:
592 		if (ifa->ifa_addr.sa_family != AF_INET) {
593 			error = EINVAL;
594 			break;
595 		}
596 		if ((ifp->if_flags & IFF_RUNNING) == 0)
597 			impinit(ifp->if_unit);
598 		break;
599 
600 	default:
601 		error = EINVAL;
602 	}
603 	splx(s);
604 	return (error);
605 }
606 
607 #ifdef IMPLEADERS
608 printleader(routine, ip)
609 	char *routine;
610 	register struct imp_leader *ip;
611 {
612 	printf("%s: ", routine);
613 	printbyte((char *)ip, 12);
614 	printf("<fmt=%x,net=%x,flags=%x,mtype=", ip->il_format, ip->il_network,
615 		ip->il_flags);
616 	if (ip->il_mtype <= IMPTYPE_READY)
617 		printf("%s,", impleaders[ip->il_mtype]);
618 	else
619 		printf("%x,", ip->il_mtype);
620 	printf("htype=%x,host=%x,imp=%x,link=", ip->il_htype, ip->il_host,
621 		ntohs(ip->il_imp));
622 	if (ip->il_link == IMPLINK_IP)
623 		printf("ip,");
624 	else
625 		printf("%x,", ip->il_link);
626 	printf("subtype=%x,len=%x>\n",ip->il_subtype,ntohs(ip->il_length)>>3);
627 }
628 
629 printbyte(cp, n)
630 	register char *cp;
631 	int n;
632 {
633 	register i, j, c;
634 
635 	for (i=0; i<n; i++) {
636 		c = *cp++;
637 		for (j=0; j<2; j++)
638 			putchar("0123456789abcdef"[(c>>((1-j)*4))&0xf]);
639 		putchar(' ');
640 	}
641 	putchar('\n');
642 }
643 #endif
644 
645 /*
646  * Routine to convert from IMP Leader to InterNet Address.
647  *
648  * This procedure is necessary because IMPs may be assigned Class A, B, or C
649  * network numbers, but only have 8 bits in the leader to reflect the
650  * IMP "network number".  The strategy is to take the network number from
651  * the ifnet structure, and blend in the host-on-imp and imp-on-net numbers
652  * from the leader.
653  *
654  * There is no support for "Logical Hosts".
655  *
656  * Class A:	Net.Host.0.Imp
657  * Class B:	Net.net.Host.Imp
658  * Class C:	Net.net.net.(Host4|Imp4)
659  */
660 imp_leader_to_addr(ap, ip, ifp)
661 	struct in_addr *ap;
662 	register struct imp_leader *ip;
663 	struct ifnet *ifp;
664 {
665 	register long final;
666 	struct in_ifaddr *ia;
667 	register struct sockaddr_in *sin;
668 	int imp = htons(ip->il_imp);
669 
670 	sin = (struct sockaddr_in *)(&ifp->if_addrlist->ifa_addr);
671 	final = htonl(sin->sin_addr.s_addr);
672 
673 	if (IN_CLASSA(final)) {
674 		final &= IN_CLASSA_NET;
675 		final |= (imp & 0xFF) | ((ip->il_host & 0xFF)<<16);
676 	} else if (IN_CLASSB(final)) {
677 		final &= IN_CLASSB_NET;
678 		final |= (imp & 0xFF) | ((ip->il_host & 0xFF)<<8);
679 	} else {
680 		final &= IN_CLASSC_NET;
681 		final |= (imp & 0x0F) | ((ip->il_host & 0x0F)<<4);
682 	}
683 	ap->s_addr = htonl(final);
684 }
685 
686 /*
687  * Function to take InterNet address and fill in IMP leader fields.
688  */
689 imp_addr_to_leader(imp, a)
690 	register struct imp_leader *imp;
691 	long a;
692 {
693 	register long addr = htonl(a);		/* host order */
694 
695 	imp->il_network = 0;	/* !! */
696 
697 	if (IN_CLASSA(addr)) {
698 		imp->il_host = ((addr>>16) & 0xFF);
699 		imp->il_imp = addr & 0xFF;
700 	} else if (IN_CLASSB(addr)) {
701 		imp->il_host = ((addr>>8) & 0xFF);
702 		imp->il_imp = addr & 0xFF;
703 	} else {
704 		imp->il_host = ((addr>>4) & 0xF);
705 		imp->il_imp = addr & 0xF;
706 	}
707 	imp->il_imp = htons(imp->il_imp);	/* network order! */
708 }
709 #endif
710