xref: /netbsd-src/sys/net/if_arcsubr.c (revision e55cffd8e520e9b03f18a1bd98bb04223e79f69f)
1 /*	$NetBSD: if_arcsubr.c,v 1.35 2001/04/13 23:30:12 thorpej Exp $	*/
2 
3 /*
4  * Copyright (c) 1994, 1995 Ignatios Souvatzis
5  * Copyright (c) 1982, 1989, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. All advertising materials mentioning features or use of this software
17  *    must display the following acknowledgement:
18  *	This product includes software developed by the University of
19  *	California, Berkeley and its contributors.
20  * 4. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  * from: NetBSD: if_ethersubr.c,v 1.9 1994/06/29 06:36:11 cgd Exp
37  *       @(#)if_ethersubr.c	8.1 (Berkeley) 6/10/93
38  *
39  */
40 #include "opt_inet.h"
41 
42 #include "bpfilter.h"
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/malloc.h>
48 #include <sys/mbuf.h>
49 #include <sys/protosw.h>
50 #include <sys/socket.h>
51 #include <sys/ioctl.h>
52 #include <sys/errno.h>
53 #include <sys/syslog.h>
54 
55 #include <machine/cpu.h>
56 
57 #include <net/if.h>
58 #include <net/netisr.h>
59 #include <net/route.h>
60 #include <net/if_dl.h>
61 #include <net/if_types.h>
62 #include <net/if_arc.h>
63 #include <net/if_arp.h>
64 #include <net/if_ether.h>
65 
66 #if NBPFILTER > 0
67 #include <net/bpf.h>
68 #endif
69 
70 #ifdef INET
71 #include <netinet/in.h>
72 #include <netinet/in_var.h>
73 #include <netinet/if_inarp.h>
74 #endif
75 
76 #ifdef INET6
77 #ifndef INET
78 #include <netinet/in.h>
79 #endif
80 #include <netinet6/in6_var.h>
81 #include <netinet6/nd6.h>
82 #endif
83 
84 #define ARCNET_ALLOW_BROKEN_ARP
85 
86 #ifndef ARC_IPMTU
87 #define ARC_IPMTU	1500
88 #endif
89 
90 static struct mbuf *arc_defrag __P((struct ifnet *, struct mbuf *));
91 
92 /*
93  * RC1201 requires us to have this configurable. We have it only per
94  * machine at the moment... there is no generic "set mtu" ioctl, AFAICS.
95  * Anyway, it is possible to binpatch this or set it per kernel config
96  * option.
97  */
98 #if ARC_IPMTU > 60480
99 ERROR: The arc_ipmtu is ARC_IPMTU, but must not exceed 60480.
100 #endif
101 int arc_ipmtu = ARC_IPMTU;
102 u_int8_t  arcbroadcastaddr = 0;
103 
104 #define senderr(e) { error = (e); goto bad;}
105 #define SIN(s) ((struct sockaddr_in *)s)
106 
107 static	int arc_output __P((struct ifnet *, struct mbuf *,
108 	    struct sockaddr *, struct rtentry *));
109 static	void arc_input __P((struct ifnet *, struct mbuf *));
110 
111 /*
112  * ARCnet output routine.
113  * Encapsulate a packet of type family for the local net.
114  * Assumes that ifp is actually pointer to arccom structure.
115  */
116 static int
117 arc_output(ifp, m0, dst, rt0)
118 	struct ifnet *ifp;
119 	struct mbuf *m0;
120 	struct sockaddr *dst;
121 	struct rtentry *rt0;
122 {
123 	struct mbuf		*m, *m1, *mcopy;
124 	struct rtentry		*rt;
125 	struct arccom		*ac;
126 	struct arc_header	*ah;
127 	struct arphdr		*arph;
128 	int			s, error, newencoding;
129 	u_int8_t		atype, adst, myself;
130 	int			tfrags, sflag, fsflag, rsflag;
131 
132 	if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
133 		return(ENETDOWN); /* m, m1 aren't initialized yet */
134 
135 	error = newencoding = 0;
136 	ac = (struct arccom *)ifp;
137 	m = m0;
138 	mcopy = m1 = NULL;
139 
140 	myself = *LLADDR(ifp->if_sadl);
141 
142 	ifp->if_lastchange = time;
143 	if ((rt = rt0)) {
144 		if ((rt->rt_flags & RTF_UP) == 0) {
145 			if ((rt0 = rt = rtalloc1(dst, 1)))
146 				rt->rt_refcnt--;
147 			else
148 				senderr(EHOSTUNREACH);
149 		}
150 		if (rt->rt_flags & RTF_GATEWAY) {
151 			if (rt->rt_gwroute == 0)
152 				goto lookup;
153 			if (((rt = rt->rt_gwroute)->rt_flags & RTF_UP) == 0) {
154 				rtfree(rt); rt = rt0;
155 			lookup: rt->rt_gwroute = rtalloc1(rt->rt_gateway, 1);
156 				if ((rt = rt->rt_gwroute) == 0)
157 					senderr(EHOSTUNREACH);
158 			}
159 		}
160 		if (rt->rt_flags & RTF_REJECT)
161 			if (rt->rt_rmx.rmx_expire == 0 ||
162 			    time.tv_sec < rt->rt_rmx.rmx_expire)
163 				senderr(rt == rt0 ? EHOSTDOWN : EHOSTUNREACH);
164 	}
165 
166 	switch (dst->sa_family) {
167 #ifdef INET
168 	case AF_INET:
169 
170 		/*
171 		 * For now, use the simple IP addr -> ARCnet addr mapping
172 		 */
173 		if (m->m_flags & (M_BCAST|M_MCAST))
174 			adst = arcbroadcastaddr; /* ARCnet broadcast address */
175 		else if (ifp->if_flags & IFF_NOARP)
176 			adst = ntohl(SIN(dst)->sin_addr.s_addr) & 0xFF;
177 		else if (!arpresolve(ifp, rt, m, dst, &adst))
178 			return 0;	/* not resolved yet */
179 
180 		/* If broadcasting on a simplex interface, loopback a copy */
181 		if ((m->m_flags & (M_BCAST|M_MCAST)) &&
182 		    (ifp->if_flags & IFF_SIMPLEX))
183 			mcopy = m_copy(m, 0, (int)M_COPYALL);
184 		if (ifp->if_flags & IFF_LINK0) {
185 			atype = ARCTYPE_IP;
186 			newencoding = 1;
187 		} else {
188 			atype = ARCTYPE_IP_OLD;
189 			newencoding = 0;
190 		}
191 		break;
192 
193 	case AF_ARP:
194 		arph = mtod(m, struct arphdr *);
195 		if (m->m_flags & M_BCAST)
196 			adst = arcbroadcastaddr;
197 		else
198 			adst = *ar_tha(arph);
199 
200 		arph->ar_hrd = htons(ARPHRD_ARCNET);
201 
202 		switch(ntohs(arph->ar_op)) {
203 
204 		case ARPOP_REVREQUEST:
205 		case ARPOP_REVREPLY:
206 			if (!(ifp->if_flags & IFF_LINK0)) {
207 				printf("%s: can't handle af%d\n",
208 				    ifp->if_xname, dst->sa_family);
209 				senderr(EAFNOSUPPORT);
210 			}
211 
212 			atype = htons(ARCTYPE_REVARP);
213 			newencoding = 1;
214 			break;
215 
216 		case ARPOP_REQUEST:
217 		case ARPOP_REPLY:
218 		default:
219 			if (ifp->if_flags & IFF_LINK0) {
220 				atype = htons(ARCTYPE_ARP);
221 				newencoding = 1;
222 			} else {
223 				atype = htons(ARCTYPE_ARP_OLD);
224 				newencoding = 0;
225 			}
226 		}
227 #ifdef ARCNET_ALLOW_BROKEN_ARP
228 		/*
229 		 * XXX It's not clear per RFC826 if this is needed, but
230 		 * "assigned numbers" say this is wrong.
231 		 * However, e.g., AmiTCP 3.0Beta used it... we make this
232 		 * switchable for emergency cases. Not perfect, but...
233 		 */
234 		if (ifp->if_flags & IFF_LINK2)
235 			arph->ar_pro = atype - 1;
236 #endif
237 		break;
238 #endif
239 #ifdef INET6
240 	case AF_INET6:
241 #ifdef OLDIP6OUTPUT
242 		if (!nd6_resolve(ifp, rt, m, dst, (u_char *)&adst))
243 			return(0);	/* if not yet resolves */
244 #else
245 		if (!nd6_storelladdr(ifp, rt, m, dst, (u_char *)&adst))
246 			return(0); /* it must be impossible, but... */
247 #endif /* OLDIP6OUTPUT */
248 		atype = htons(ARCTYPE_INET6);
249 		newencoding = 1;
250 		break;
251 #endif
252 
253 	case AF_UNSPEC:
254 		ah = (struct arc_header *)dst->sa_data;
255  		adst = ah->arc_dhost;
256 		atype = ah->arc_type;
257 		break;
258 
259 	default:
260 		printf("%s: can't handle af%d\n", ifp->if_xname,
261 		    dst->sa_family);
262 		senderr(EAFNOSUPPORT);
263 	}
264 
265 	if (mcopy)
266 		(void) looutput(ifp, mcopy, dst, rt);
267 
268 	/*
269 	 * Add local net header.  If no space in first mbuf,
270 	 * allocate another.
271 	 *
272 	 * For ARCnet, this is just symbolic. The header changes
273 	 * form and position on its way into the hardware and out of
274 	 * the wire.  At this point, it contains source, destination and
275 	 * packet type.
276 	 */
277 	if (newencoding) {
278 		++ac->ac_seqid; /* make the seqid unique */
279 
280 		tfrags = (m->m_pkthdr.len + 503) / 504;
281 		fsflag = 2 * tfrags - 3;
282 		sflag = 0;
283 		rsflag = fsflag;
284 
285 		while (sflag < fsflag) {
286 			/* we CAN'T have short packets here */
287 			m1 = m_split(m, 504, M_DONTWAIT);
288 			if (m1 == 0)
289 				senderr(ENOBUFS);
290 
291 			M_PREPEND(m, ARC_HDRNEWLEN, M_DONTWAIT);
292 			if (m == 0)
293 				senderr(ENOBUFS);
294 			ah = mtod(m, struct arc_header *);
295 			ah->arc_type = atype;
296 			ah->arc_dhost = adst;
297 			ah->arc_shost = myself;
298 			ah->arc_flag = rsflag;
299 			ah->arc_seqid = ac->ac_seqid;
300 
301 			s = splnet();
302 			/*
303 			 * Queue message on interface, and start output if
304 			 * interface not yet active.
305 			 */
306 			if (IF_QFULL(&ifp->if_snd)) {
307 				IF_DROP(&ifp->if_snd);
308 				splx(s);
309 				senderr(ENOBUFS);
310 			}
311 			ifp->if_obytes += m->m_pkthdr.len;
312 			IF_ENQUEUE(&ifp->if_snd, m);
313 			if ((ifp->if_flags & IFF_OACTIVE) == 0)
314 				(*ifp->if_start)(ifp);
315 			splx(s);
316 
317 			m = m1;
318 			sflag += 2;
319 			rsflag = sflag;
320 		}
321 		m1 = NULL;
322 
323 
324 		/* here we can have small, especially forbidden packets */
325 
326 		if ((m->m_pkthdr.len >=
327 		    ARC_MIN_FORBID_LEN - ARC_HDRNEWLEN + 2) &&
328 		    (m->m_pkthdr.len <=
329 		    ARC_MAX_FORBID_LEN - ARC_HDRNEWLEN + 2)) {
330 
331 			M_PREPEND(m, ARC_HDRNEWLEN_EXC, M_DONTWAIT);
332 			if (m == 0)
333 				senderr(ENOBUFS);
334 			ah = mtod(m, struct arc_header *);
335 			ah->arc_flag = 0xFF;
336 			ah->arc_seqid = 0xFFFF;
337 			ah->arc_type2 = atype;
338 			ah->arc_flag2 = sflag;
339 			ah->arc_seqid2 = ac->ac_seqid;
340 		} else {
341 			M_PREPEND(m, ARC_HDRNEWLEN, M_DONTWAIT);
342 			if (m == 0)
343 				senderr(ENOBUFS);
344 			ah = mtod(m, struct arc_header *);
345 			ah->arc_flag = sflag;
346 			ah->arc_seqid = ac->ac_seqid;
347 		}
348 
349 		ah->arc_dhost = adst;
350 		ah->arc_shost = myself;
351 		ah->arc_type = atype;
352 	} else {
353 		M_PREPEND(m, ARC_HDRLEN, M_DONTWAIT);
354 		if (m == 0)
355 			senderr(ENOBUFS);
356 		ah = mtod(m, struct arc_header *);
357 		ah->arc_type = atype;
358 		ah->arc_dhost = adst;
359 		ah->arc_shost = myself;
360 	}
361 	s = splnet();
362 	/*
363 	 * Queue message on interface, and start output if interface
364 	 * not yet active.
365 	 */
366 	if (IF_QFULL(&ifp->if_snd)) {
367 		IF_DROP(&ifp->if_snd);
368 		splx(s);
369 		senderr(ENOBUFS);
370 	}
371 	ifp->if_obytes += m->m_pkthdr.len;
372 	IF_ENQUEUE(&ifp->if_snd, m);
373 	if ((ifp->if_flags & IFF_OACTIVE) == 0)
374 		(*ifp->if_start)(ifp);
375 	splx(s);
376 
377 	return (error);
378 
379 bad:
380 	if (m1)
381 		m_freem(m1);
382 	if (m)
383 		m_freem(m);
384 	return (error);
385 }
386 
387 /*
388  * Defragmenter. Returns mbuf if last packet found, else
389  * NULL. frees imcoming mbuf as necessary.
390  */
391 
392 __inline struct mbuf *
393 arc_defrag(ifp, m)
394 	struct ifnet *ifp;
395 	struct mbuf *m;
396 {
397 	struct arc_header *ah, *ah1;
398 	struct arccom *ac;
399 	struct ac_frag *af;
400 	struct mbuf *m1;
401 	char *s;
402 	int newflen;
403 	u_char src,dst,typ;
404 
405 	ac = (struct arccom *)ifp;
406 
407 	if (m->m_len < ARC_HDRNEWLEN) {
408 		m = m_pullup(m, ARC_HDRNEWLEN);
409 		if (m == NULL) {
410 			++ifp->if_ierrors;
411 			return NULL;
412 		}
413 	}
414 
415 	ah = mtod(m, struct arc_header *);
416 	typ = ah->arc_type;
417 
418 	if (!arc_isphds(typ))
419 		return m;
420 
421 	src = ah->arc_shost;
422 	dst = ah->arc_dhost;
423 
424 	if (ah->arc_flag == 0xff) {
425 		m_adj(m, 4);
426 
427 		if (m->m_len < ARC_HDRNEWLEN) {
428 			m = m_pullup(m, ARC_HDRNEWLEN);
429 			if (m == NULL) {
430 				++ifp->if_ierrors;
431 				return NULL;
432 			}
433 		}
434 
435 		ah = mtod(m, struct arc_header *);
436 	}
437 
438 	af = &ac->ac_fragtab[src];
439 	m1 = af->af_packet;
440 	s = "debug code error";
441 
442 	if (ah->arc_flag & 1) {
443 		/*
444 		 * first fragment. We always initialize, which is
445 		 * about the right thing to do, as we only want to
446 		 * accept one fragmented packet per src at a time.
447 		 */
448 		if (m1 != NULL)
449 			m_freem(m1);
450 
451 		af->af_packet = m;
452 		m1 = m;
453 		af->af_maxflag = ah->arc_flag;
454 		af->af_lastseen = 0;
455 		af->af_seqid = ah->arc_seqid;
456 
457 		return NULL;
458 		/* notreached */
459 	} else {
460 		/* check for unfragmented packet */
461 		if (ah->arc_flag == 0)
462 			return m;
463 
464 		/* do we have a first packet from that src? */
465 		if (m1 == NULL) {
466 			s = "no first frag";
467 			goto outofseq;
468 		}
469 
470 		ah1 = mtod(m1, struct arc_header *);
471 
472 		if (ah->arc_seqid != ah1->arc_seqid) {
473 			s = "seqid differs";
474 			goto outofseq;
475 		}
476 
477 		if (typ != ah1->arc_type) {
478 			s = "type differs";
479 			goto outofseq;
480 		}
481 
482 		if (dst != ah1->arc_dhost) {
483 			s = "dest host differs";
484 			goto outofseq;
485 		}
486 
487 		/* typ, seqid and dst are ok here. */
488 
489 		if (ah->arc_flag == af->af_lastseen) {
490 			m_freem(m);
491 			return NULL;
492 		}
493 
494 		if (ah->arc_flag == af->af_lastseen + 2) {
495 			/* ok, this is next fragment */
496 			af->af_lastseen = ah->arc_flag;
497 			m_adj(m,ARC_HDRNEWLEN);
498 
499 			/*
500 			 * m_cat might free the first mbuf (with pkthdr)
501 			 * in 2nd chain; therefore:
502 			 */
503 
504 			newflen = m->m_pkthdr.len;
505 
506 			m_cat(m1,m);
507 
508 			m1->m_pkthdr.len += newflen;
509 
510 			/* is it the last one? */
511 			if (af->af_lastseen > af->af_maxflag) {
512 				af->af_packet = NULL;
513 				return(m1);
514 			} else
515 				return NULL;
516 		}
517 		s = "other reason";
518 		/* if all else fails, it is out of sequence, too */
519 	}
520 outofseq:
521 	if (m1) {
522 		m_freem(m1);
523 		af->af_packet = NULL;
524 	}
525 
526 	if (m)
527 		m_freem(m);
528 
529 	log(LOG_INFO,"%s: got out of seq. packet: %s\n",
530 	    ifp->if_xname, s);
531 
532 	return NULL;
533 }
534 
535 /*
536  * return 1 if Packet Header Definition Standard, else 0.
537  * For now: old IP, old ARP aren't obviously. Lacking correct information,
538  * we guess that besides new IP and new ARP also IPX and APPLETALK are PHDS.
539  * (Apple and Novell corporations were involved, among others, in PHDS work).
540  * Easiest is to assume that everybody else uses that, too.
541  */
542 int
543 arc_isphds(type)
544 	u_int8_t type;
545 {
546 	return (type != ARCTYPE_IP_OLD &&
547 		type != ARCTYPE_ARP_OLD &&
548 		type != ARCTYPE_DIAGNOSE);
549 }
550 
551 /*
552  * Process a received Arcnet packet;
553  * the packet is in the mbuf chain m with
554  * the ARCnet header.
555  */
556 static void
557 arc_input(ifp, m)
558 	struct ifnet *ifp;
559 	struct mbuf *m;
560 {
561 	struct arc_header *ah;
562 	struct ifqueue *inq;
563 	u_int8_t atype;
564 	int s;
565 	struct arphdr *arph;
566 
567 	if ((ifp->if_flags & IFF_UP) == 0) {
568 		m_freem(m);
569 		return;
570 	}
571 
572 	/* possibly defragment: */
573 	m = arc_defrag(ifp, m);
574 	if (m == NULL)
575 		return;
576 
577 	ah = mtod(m, struct arc_header *);
578 
579 	ifp->if_lastchange = time;
580 	ifp->if_ibytes += m->m_pkthdr.len;
581 
582 	if (arcbroadcastaddr == ah->arc_dhost) {
583 		m->m_flags |= M_BCAST|M_MCAST;
584 		ifp->if_imcasts++;
585 	}
586 
587 	atype = ah->arc_type;
588 	switch (atype) {
589 #ifdef INET
590 	case ARCTYPE_IP:
591 		m_adj(m, ARC_HDRNEWLEN);
592 		schednetisr(NETISR_IP);
593 		inq = &ipintrq;
594 		break;
595 
596 	case ARCTYPE_IP_OLD:
597 		m_adj(m, ARC_HDRLEN);
598 		schednetisr(NETISR_IP);
599 		inq = &ipintrq;
600 		break;
601 
602 	case ARCTYPE_ARP:
603 		m_adj(m, ARC_HDRNEWLEN);
604 		schednetisr(NETISR_ARP);
605 		inq = &arpintrq;
606 #ifdef ARCNET_ALLOW_BROKEN_ARP
607 		mtod(m, struct arphdr *)->ar_pro = htons(ETHERTYPE_IP);
608 #endif
609 		break;
610 
611 	case ARCTYPE_ARP_OLD:
612 		m_adj(m, ARC_HDRLEN);
613 		schednetisr(NETISR_ARP);
614 		inq = &arpintrq;
615 		arph = mtod(m, struct arphdr *);
616 #ifdef ARCNET_ALLOW_BROKEN_ARP
617 		mtod(m, struct arphdr *)->ar_pro = htons(ETHERTYPE_IP);
618 #endif
619 		break;
620 #endif
621 #ifdef INET6
622 	case ARCTYPE_INET6:
623 		m_adj(m, ARC_HDRNEWLEN);
624 		schednetisr(NETISR_IPV6);
625 		inq = &ip6intrq;
626 		break;
627 #endif
628 	default:
629 		m_freem(m);
630 		return;
631 	}
632 
633 	s = splnet();
634 	if (IF_QFULL(inq)) {
635 		IF_DROP(inq);
636 		m_freem(m);
637 	} else
638 		IF_ENQUEUE(inq, m);
639 	splx(s);
640 }
641 
642 /*
643  * Convert Arcnet address to printable (loggable) representation.
644  */
645 static char digits[] = "0123456789abcdef";
646 char *
647 arc_sprintf(ap)
648 	u_int8_t *ap;
649 {
650 	static char arcbuf[3];
651 	char *cp = arcbuf;
652 
653 	*cp++ = digits[*ap >> 4];
654 	*cp++ = digits[*ap++ & 0xf];
655 	*cp   = 0;
656 	return (arcbuf);
657 }
658 
659 /*
660  * Register (new) link level address.
661  */
662 void
663 arc_storelladdr(ifp, lla)
664 	struct ifnet *ifp;
665 	u_int8_t lla;
666 {
667 
668 	*(LLADDR(ifp->if_sadl)) = lla;
669 	ifp->if_mtu = ARC_PHDS_MAXMTU;
670 }
671 
672 /*
673  * Perform common duties while attaching to interface list
674  */
675 void
676 arc_ifattach(ifp, lla)
677 	struct ifnet *ifp;
678 	u_int8_t lla;
679 {
680 	struct arccom *ac;
681 
682 	ifp->if_type = IFT_ARCNET;
683 	ifp->if_addrlen = 1;
684 	ifp->if_hdrlen = ARC_HDRLEN;
685 	ifp->if_dlt = DLT_ARCNET;
686 	if (ifp->if_flags & IFF_BROADCAST)
687 		ifp->if_flags |= IFF_MULTICAST|IFF_ALLMULTI;
688 	if (ifp->if_flags & IFF_LINK0 && arc_ipmtu > ARC_PHDS_MAXMTU)
689 		log(LOG_ERR,
690 		    "%s: arc_ipmtu is %d, but must not exceed %d",
691 		    ifp->if_xname, arc_ipmtu, ARC_PHDS_MAXMTU);
692 
693 	ifp->if_output = arc_output;
694 	ifp->if_input = arc_input;
695 	ac = (struct arccom *)ifp;
696 	ac->ac_seqid = (time.tv_sec) & 0xFFFF; /* try to make seqid unique */
697 	if (lla == 0) {
698 		/* XXX this message isn't entirely clear, to me -- cgd */
699 		log(LOG_ERR,"%s: link address 0 reserved for broadcasts.  Please change it and ifconfig %s down up\n",
700 		   ifp->if_xname, ifp->if_xname);
701 	}
702 	if_attach(ifp);
703 	if_alloc_sadl(ifp);
704 	arc_storelladdr(ifp, lla);
705 
706 	ifp->if_broadcastaddr = &arcbroadcastaddr;
707 
708 #if NBPFILTER > 0
709 	bpfattach(ifp, DLT_ARCNET, ARC_HDRLEN);
710 #endif
711 }
712