xref: /netbsd-src/sys/net/if_arcsubr.c (revision 3b01aba77a7a698587faaae455bbfe740923c1f5)
1 /*	$NetBSD: if_arcsubr.c,v 1.36 2001/06/14 05:44:23 itojun 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 	if ((rt = rt0)) {
143 		if ((rt->rt_flags & RTF_UP) == 0) {
144 			if ((rt0 = rt = rtalloc1(dst, 1)))
145 				rt->rt_refcnt--;
146 			else
147 				senderr(EHOSTUNREACH);
148 		}
149 		if (rt->rt_flags & RTF_GATEWAY) {
150 			if (rt->rt_gwroute == 0)
151 				goto lookup;
152 			if (((rt = rt->rt_gwroute)->rt_flags & RTF_UP) == 0) {
153 				rtfree(rt); rt = rt0;
154 			lookup: rt->rt_gwroute = rtalloc1(rt->rt_gateway, 1);
155 				if ((rt = rt->rt_gwroute) == 0)
156 					senderr(EHOSTUNREACH);
157 			}
158 		}
159 		if (rt->rt_flags & RTF_REJECT)
160 			if (rt->rt_rmx.rmx_expire == 0 ||
161 			    time.tv_sec < rt->rt_rmx.rmx_expire)
162 				senderr(rt == rt0 ? EHOSTDOWN : EHOSTUNREACH);
163 	}
164 
165 	switch (dst->sa_family) {
166 #ifdef INET
167 	case AF_INET:
168 
169 		/*
170 		 * For now, use the simple IP addr -> ARCnet addr mapping
171 		 */
172 		if (m->m_flags & (M_BCAST|M_MCAST))
173 			adst = arcbroadcastaddr; /* ARCnet broadcast address */
174 		else if (ifp->if_flags & IFF_NOARP)
175 			adst = ntohl(SIN(dst)->sin_addr.s_addr) & 0xFF;
176 		else if (!arpresolve(ifp, rt, m, dst, &adst))
177 			return 0;	/* not resolved yet */
178 
179 		/* If broadcasting on a simplex interface, loopback a copy */
180 		if ((m->m_flags & (M_BCAST|M_MCAST)) &&
181 		    (ifp->if_flags & IFF_SIMPLEX))
182 			mcopy = m_copy(m, 0, (int)M_COPYALL);
183 		if (ifp->if_flags & IFF_LINK0) {
184 			atype = ARCTYPE_IP;
185 			newencoding = 1;
186 		} else {
187 			atype = ARCTYPE_IP_OLD;
188 			newencoding = 0;
189 		}
190 		break;
191 
192 	case AF_ARP:
193 		arph = mtod(m, struct arphdr *);
194 		if (m->m_flags & M_BCAST)
195 			adst = arcbroadcastaddr;
196 		else
197 			adst = *ar_tha(arph);
198 
199 		arph->ar_hrd = htons(ARPHRD_ARCNET);
200 
201 		switch(ntohs(arph->ar_op)) {
202 
203 		case ARPOP_REVREQUEST:
204 		case ARPOP_REVREPLY:
205 			if (!(ifp->if_flags & IFF_LINK0)) {
206 				printf("%s: can't handle af%d\n",
207 				    ifp->if_xname, dst->sa_family);
208 				senderr(EAFNOSUPPORT);
209 			}
210 
211 			atype = htons(ARCTYPE_REVARP);
212 			newencoding = 1;
213 			break;
214 
215 		case ARPOP_REQUEST:
216 		case ARPOP_REPLY:
217 		default:
218 			if (ifp->if_flags & IFF_LINK0) {
219 				atype = htons(ARCTYPE_ARP);
220 				newencoding = 1;
221 			} else {
222 				atype = htons(ARCTYPE_ARP_OLD);
223 				newencoding = 0;
224 			}
225 		}
226 #ifdef ARCNET_ALLOW_BROKEN_ARP
227 		/*
228 		 * XXX It's not clear per RFC826 if this is needed, but
229 		 * "assigned numbers" say this is wrong.
230 		 * However, e.g., AmiTCP 3.0Beta used it... we make this
231 		 * switchable for emergency cases. Not perfect, but...
232 		 */
233 		if (ifp->if_flags & IFF_LINK2)
234 			arph->ar_pro = atype - 1;
235 #endif
236 		break;
237 #endif
238 #ifdef INET6
239 	case AF_INET6:
240 #ifdef OLDIP6OUTPUT
241 		if (!nd6_resolve(ifp, rt, m, dst, (u_char *)&adst))
242 			return(0);	/* if not yet resolves */
243 #else
244 		if (!nd6_storelladdr(ifp, rt, m, dst, (u_char *)&adst))
245 			return(0); /* it must be impossible, but... */
246 #endif /* OLDIP6OUTPUT */
247 		atype = htons(ARCTYPE_INET6);
248 		newencoding = 1;
249 		break;
250 #endif
251 
252 	case AF_UNSPEC:
253 		ah = (struct arc_header *)dst->sa_data;
254  		adst = ah->arc_dhost;
255 		atype = ah->arc_type;
256 		break;
257 
258 	default:
259 		printf("%s: can't handle af%d\n", ifp->if_xname,
260 		    dst->sa_family);
261 		senderr(EAFNOSUPPORT);
262 	}
263 
264 	if (mcopy)
265 		(void) looutput(ifp, mcopy, dst, rt);
266 
267 	/*
268 	 * Add local net header.  If no space in first mbuf,
269 	 * allocate another.
270 	 *
271 	 * For ARCnet, this is just symbolic. The header changes
272 	 * form and position on its way into the hardware and out of
273 	 * the wire.  At this point, it contains source, destination and
274 	 * packet type.
275 	 */
276 	if (newencoding) {
277 		++ac->ac_seqid; /* make the seqid unique */
278 
279 		tfrags = (m->m_pkthdr.len + 503) / 504;
280 		fsflag = 2 * tfrags - 3;
281 		sflag = 0;
282 		rsflag = fsflag;
283 
284 		while (sflag < fsflag) {
285 			/* we CAN'T have short packets here */
286 			m1 = m_split(m, 504, M_DONTWAIT);
287 			if (m1 == 0)
288 				senderr(ENOBUFS);
289 
290 			M_PREPEND(m, ARC_HDRNEWLEN, M_DONTWAIT);
291 			if (m == 0)
292 				senderr(ENOBUFS);
293 			ah = mtod(m, struct arc_header *);
294 			ah->arc_type = atype;
295 			ah->arc_dhost = adst;
296 			ah->arc_shost = myself;
297 			ah->arc_flag = rsflag;
298 			ah->arc_seqid = ac->ac_seqid;
299 
300 			s = splnet();
301 			/*
302 			 * Queue message on interface, and start output if
303 			 * interface not yet active.
304 			 */
305 			if (IF_QFULL(&ifp->if_snd)) {
306 				IF_DROP(&ifp->if_snd);
307 				splx(s);
308 				senderr(ENOBUFS);
309 			}
310 			ifp->if_obytes += m->m_pkthdr.len;
311 			IF_ENQUEUE(&ifp->if_snd, m);
312 			if ((ifp->if_flags & IFF_OACTIVE) == 0)
313 				(*ifp->if_start)(ifp);
314 			splx(s);
315 
316 			m = m1;
317 			sflag += 2;
318 			rsflag = sflag;
319 		}
320 		m1 = NULL;
321 
322 
323 		/* here we can have small, especially forbidden packets */
324 
325 		if ((m->m_pkthdr.len >=
326 		    ARC_MIN_FORBID_LEN - ARC_HDRNEWLEN + 2) &&
327 		    (m->m_pkthdr.len <=
328 		    ARC_MAX_FORBID_LEN - ARC_HDRNEWLEN + 2)) {
329 
330 			M_PREPEND(m, ARC_HDRNEWLEN_EXC, M_DONTWAIT);
331 			if (m == 0)
332 				senderr(ENOBUFS);
333 			ah = mtod(m, struct arc_header *);
334 			ah->arc_flag = 0xFF;
335 			ah->arc_seqid = 0xFFFF;
336 			ah->arc_type2 = atype;
337 			ah->arc_flag2 = sflag;
338 			ah->arc_seqid2 = ac->ac_seqid;
339 		} else {
340 			M_PREPEND(m, ARC_HDRNEWLEN, M_DONTWAIT);
341 			if (m == 0)
342 				senderr(ENOBUFS);
343 			ah = mtod(m, struct arc_header *);
344 			ah->arc_flag = sflag;
345 			ah->arc_seqid = ac->ac_seqid;
346 		}
347 
348 		ah->arc_dhost = adst;
349 		ah->arc_shost = myself;
350 		ah->arc_type = atype;
351 	} else {
352 		M_PREPEND(m, ARC_HDRLEN, M_DONTWAIT);
353 		if (m == 0)
354 			senderr(ENOBUFS);
355 		ah = mtod(m, struct arc_header *);
356 		ah->arc_type = atype;
357 		ah->arc_dhost = adst;
358 		ah->arc_shost = myself;
359 	}
360 	s = splnet();
361 	/*
362 	 * Queue message on interface, and start output if interface
363 	 * not yet active.
364 	 */
365 	if (IF_QFULL(&ifp->if_snd)) {
366 		IF_DROP(&ifp->if_snd);
367 		splx(s);
368 		senderr(ENOBUFS);
369 	}
370 	ifp->if_obytes += m->m_pkthdr.len;
371 	IF_ENQUEUE(&ifp->if_snd, m);
372 	if ((ifp->if_flags & IFF_OACTIVE) == 0)
373 		(*ifp->if_start)(ifp);
374 	splx(s);
375 
376 	return (error);
377 
378 bad:
379 	if (m1)
380 		m_freem(m1);
381 	if (m)
382 		m_freem(m);
383 	return (error);
384 }
385 
386 /*
387  * Defragmenter. Returns mbuf if last packet found, else
388  * NULL. frees imcoming mbuf as necessary.
389  */
390 
391 __inline struct mbuf *
392 arc_defrag(ifp, m)
393 	struct ifnet *ifp;
394 	struct mbuf *m;
395 {
396 	struct arc_header *ah, *ah1;
397 	struct arccom *ac;
398 	struct ac_frag *af;
399 	struct mbuf *m1;
400 	char *s;
401 	int newflen;
402 	u_char src,dst,typ;
403 
404 	ac = (struct arccom *)ifp;
405 
406 	if (m->m_len < ARC_HDRNEWLEN) {
407 		m = m_pullup(m, ARC_HDRNEWLEN);
408 		if (m == NULL) {
409 			++ifp->if_ierrors;
410 			return NULL;
411 		}
412 	}
413 
414 	ah = mtod(m, struct arc_header *);
415 	typ = ah->arc_type;
416 
417 	if (!arc_isphds(typ))
418 		return m;
419 
420 	src = ah->arc_shost;
421 	dst = ah->arc_dhost;
422 
423 	if (ah->arc_flag == 0xff) {
424 		m_adj(m, 4);
425 
426 		if (m->m_len < ARC_HDRNEWLEN) {
427 			m = m_pullup(m, ARC_HDRNEWLEN);
428 			if (m == NULL) {
429 				++ifp->if_ierrors;
430 				return NULL;
431 			}
432 		}
433 
434 		ah = mtod(m, struct arc_header *);
435 	}
436 
437 	af = &ac->ac_fragtab[src];
438 	m1 = af->af_packet;
439 	s = "debug code error";
440 
441 	if (ah->arc_flag & 1) {
442 		/*
443 		 * first fragment. We always initialize, which is
444 		 * about the right thing to do, as we only want to
445 		 * accept one fragmented packet per src at a time.
446 		 */
447 		if (m1 != NULL)
448 			m_freem(m1);
449 
450 		af->af_packet = m;
451 		m1 = m;
452 		af->af_maxflag = ah->arc_flag;
453 		af->af_lastseen = 0;
454 		af->af_seqid = ah->arc_seqid;
455 
456 		return NULL;
457 		/* notreached */
458 	} else {
459 		/* check for unfragmented packet */
460 		if (ah->arc_flag == 0)
461 			return m;
462 
463 		/* do we have a first packet from that src? */
464 		if (m1 == NULL) {
465 			s = "no first frag";
466 			goto outofseq;
467 		}
468 
469 		ah1 = mtod(m1, struct arc_header *);
470 
471 		if (ah->arc_seqid != ah1->arc_seqid) {
472 			s = "seqid differs";
473 			goto outofseq;
474 		}
475 
476 		if (typ != ah1->arc_type) {
477 			s = "type differs";
478 			goto outofseq;
479 		}
480 
481 		if (dst != ah1->arc_dhost) {
482 			s = "dest host differs";
483 			goto outofseq;
484 		}
485 
486 		/* typ, seqid and dst are ok here. */
487 
488 		if (ah->arc_flag == af->af_lastseen) {
489 			m_freem(m);
490 			return NULL;
491 		}
492 
493 		if (ah->arc_flag == af->af_lastseen + 2) {
494 			/* ok, this is next fragment */
495 			af->af_lastseen = ah->arc_flag;
496 			m_adj(m,ARC_HDRNEWLEN);
497 
498 			/*
499 			 * m_cat might free the first mbuf (with pkthdr)
500 			 * in 2nd chain; therefore:
501 			 */
502 
503 			newflen = m->m_pkthdr.len;
504 
505 			m_cat(m1,m);
506 
507 			m1->m_pkthdr.len += newflen;
508 
509 			/* is it the last one? */
510 			if (af->af_lastseen > af->af_maxflag) {
511 				af->af_packet = NULL;
512 				return(m1);
513 			} else
514 				return NULL;
515 		}
516 		s = "other reason";
517 		/* if all else fails, it is out of sequence, too */
518 	}
519 outofseq:
520 	if (m1) {
521 		m_freem(m1);
522 		af->af_packet = NULL;
523 	}
524 
525 	if (m)
526 		m_freem(m);
527 
528 	log(LOG_INFO,"%s: got out of seq. packet: %s\n",
529 	    ifp->if_xname, s);
530 
531 	return NULL;
532 }
533 
534 /*
535  * return 1 if Packet Header Definition Standard, else 0.
536  * For now: old IP, old ARP aren't obviously. Lacking correct information,
537  * we guess that besides new IP and new ARP also IPX and APPLETALK are PHDS.
538  * (Apple and Novell corporations were involved, among others, in PHDS work).
539  * Easiest is to assume that everybody else uses that, too.
540  */
541 int
542 arc_isphds(type)
543 	u_int8_t type;
544 {
545 	return (type != ARCTYPE_IP_OLD &&
546 		type != ARCTYPE_ARP_OLD &&
547 		type != ARCTYPE_DIAGNOSE);
548 }
549 
550 /*
551  * Process a received Arcnet packet;
552  * the packet is in the mbuf chain m with
553  * the ARCnet header.
554  */
555 static void
556 arc_input(ifp, m)
557 	struct ifnet *ifp;
558 	struct mbuf *m;
559 {
560 	struct arc_header *ah;
561 	struct ifqueue *inq;
562 	u_int8_t atype;
563 	int s;
564 	struct arphdr *arph;
565 
566 	if ((ifp->if_flags & IFF_UP) == 0) {
567 		m_freem(m);
568 		return;
569 	}
570 
571 	/* possibly defragment: */
572 	m = arc_defrag(ifp, m);
573 	if (m == NULL)
574 		return;
575 
576 	ah = mtod(m, struct arc_header *);
577 
578 	ifp->if_ibytes += m->m_pkthdr.len;
579 
580 	if (arcbroadcastaddr == ah->arc_dhost) {
581 		m->m_flags |= M_BCAST|M_MCAST;
582 		ifp->if_imcasts++;
583 	}
584 
585 	atype = ah->arc_type;
586 	switch (atype) {
587 #ifdef INET
588 	case ARCTYPE_IP:
589 		m_adj(m, ARC_HDRNEWLEN);
590 		schednetisr(NETISR_IP);
591 		inq = &ipintrq;
592 		break;
593 
594 	case ARCTYPE_IP_OLD:
595 		m_adj(m, ARC_HDRLEN);
596 		schednetisr(NETISR_IP);
597 		inq = &ipintrq;
598 		break;
599 
600 	case ARCTYPE_ARP:
601 		m_adj(m, ARC_HDRNEWLEN);
602 		schednetisr(NETISR_ARP);
603 		inq = &arpintrq;
604 #ifdef ARCNET_ALLOW_BROKEN_ARP
605 		mtod(m, struct arphdr *)->ar_pro = htons(ETHERTYPE_IP);
606 #endif
607 		break;
608 
609 	case ARCTYPE_ARP_OLD:
610 		m_adj(m, ARC_HDRLEN);
611 		schednetisr(NETISR_ARP);
612 		inq = &arpintrq;
613 		arph = mtod(m, struct arphdr *);
614 #ifdef ARCNET_ALLOW_BROKEN_ARP
615 		mtod(m, struct arphdr *)->ar_pro = htons(ETHERTYPE_IP);
616 #endif
617 		break;
618 #endif
619 #ifdef INET6
620 	case ARCTYPE_INET6:
621 		m_adj(m, ARC_HDRNEWLEN);
622 		schednetisr(NETISR_IPV6);
623 		inq = &ip6intrq;
624 		break;
625 #endif
626 	default:
627 		m_freem(m);
628 		return;
629 	}
630 
631 	s = splnet();
632 	if (IF_QFULL(inq)) {
633 		IF_DROP(inq);
634 		m_freem(m);
635 	} else
636 		IF_ENQUEUE(inq, m);
637 	splx(s);
638 }
639 
640 /*
641  * Convert Arcnet address to printable (loggable) representation.
642  */
643 static char digits[] = "0123456789abcdef";
644 char *
645 arc_sprintf(ap)
646 	u_int8_t *ap;
647 {
648 	static char arcbuf[3];
649 	char *cp = arcbuf;
650 
651 	*cp++ = digits[*ap >> 4];
652 	*cp++ = digits[*ap++ & 0xf];
653 	*cp   = 0;
654 	return (arcbuf);
655 }
656 
657 /*
658  * Register (new) link level address.
659  */
660 void
661 arc_storelladdr(ifp, lla)
662 	struct ifnet *ifp;
663 	u_int8_t lla;
664 {
665 
666 	*(LLADDR(ifp->if_sadl)) = lla;
667 	ifp->if_mtu = ARC_PHDS_MAXMTU;
668 }
669 
670 /*
671  * Perform common duties while attaching to interface list
672  */
673 void
674 arc_ifattach(ifp, lla)
675 	struct ifnet *ifp;
676 	u_int8_t lla;
677 {
678 	struct arccom *ac;
679 
680 	ifp->if_type = IFT_ARCNET;
681 	ifp->if_addrlen = 1;
682 	ifp->if_hdrlen = ARC_HDRLEN;
683 	ifp->if_dlt = DLT_ARCNET;
684 	if (ifp->if_flags & IFF_BROADCAST)
685 		ifp->if_flags |= IFF_MULTICAST|IFF_ALLMULTI;
686 	if (ifp->if_flags & IFF_LINK0 && arc_ipmtu > ARC_PHDS_MAXMTU)
687 		log(LOG_ERR,
688 		    "%s: arc_ipmtu is %d, but must not exceed %d",
689 		    ifp->if_xname, arc_ipmtu, ARC_PHDS_MAXMTU);
690 
691 	ifp->if_output = arc_output;
692 	ifp->if_input = arc_input;
693 	ac = (struct arccom *)ifp;
694 	ac->ac_seqid = (time.tv_sec) & 0xFFFF; /* try to make seqid unique */
695 	if (lla == 0) {
696 		/* XXX this message isn't entirely clear, to me -- cgd */
697 		log(LOG_ERR,"%s: link address 0 reserved for broadcasts.  Please change it and ifconfig %s down up\n",
698 		   ifp->if_xname, ifp->if_xname);
699 	}
700 	if_attach(ifp);
701 	if_alloc_sadl(ifp);
702 	arc_storelladdr(ifp, lla);
703 
704 	ifp->if_broadcastaddr = &arcbroadcastaddr;
705 
706 #if NBPFILTER > 0
707 	bpfattach(ifp, DLT_ARCNET, ARC_HDRLEN);
708 #endif
709 }
710