xref: /netbsd-src/sys/net/if_arcsubr.c (revision 1ca5c1b28139779176bd5c13ad7c5f25c0bcd5f8)
1 /*	$NetBSD: if_arcsubr.c,v 1.38 2001/11/12 23:49:35 lukem 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 
41 #include <sys/cdefs.h>
42 __KERNEL_RCSID(0, "$NetBSD: if_arcsubr.c,v 1.38 2001/11/12 23:49:35 lukem Exp $");
43 
44 #include "opt_inet.h"
45 
46 #include "bpfilter.h"
47 
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/kernel.h>
51 #include <sys/malloc.h>
52 #include <sys/mbuf.h>
53 #include <sys/protosw.h>
54 #include <sys/socket.h>
55 #include <sys/ioctl.h>
56 #include <sys/errno.h>
57 #include <sys/syslog.h>
58 
59 #include <machine/cpu.h>
60 
61 #include <net/if.h>
62 #include <net/netisr.h>
63 #include <net/route.h>
64 #include <net/if_dl.h>
65 #include <net/if_types.h>
66 #include <net/if_arc.h>
67 #include <net/if_arp.h>
68 #include <net/if_ether.h>
69 
70 #if NBPFILTER > 0
71 #include <net/bpf.h>
72 #endif
73 
74 #ifdef INET
75 #include <netinet/in.h>
76 #include <netinet/in_var.h>
77 #include <netinet/if_inarp.h>
78 #endif
79 
80 #ifdef INET6
81 #ifndef INET
82 #include <netinet/in.h>
83 #endif
84 #include <netinet6/in6_var.h>
85 #include <netinet6/nd6.h>
86 #endif
87 
88 #define ARCNET_ALLOW_BROKEN_ARP
89 
90 #ifndef ARC_IPMTU
91 #define ARC_IPMTU	1500
92 #endif
93 
94 static struct mbuf *arc_defrag __P((struct ifnet *, struct mbuf *));
95 
96 /*
97  * RC1201 requires us to have this configurable. We have it only per
98  * machine at the moment... there is no generic "set mtu" ioctl, AFAICS.
99  * Anyway, it is possible to binpatch this or set it per kernel config
100  * option.
101  */
102 #if ARC_IPMTU > 60480
103 ERROR: The arc_ipmtu is ARC_IPMTU, but must not exceed 60480.
104 #endif
105 int arc_ipmtu = ARC_IPMTU;
106 u_int8_t  arcbroadcastaddr = 0;
107 
108 #define senderr(e) { error = (e); goto bad;}
109 #define SIN(s) ((struct sockaddr_in *)s)
110 
111 static	int arc_output __P((struct ifnet *, struct mbuf *,
112 	    struct sockaddr *, struct rtentry *));
113 static	void arc_input __P((struct ifnet *, struct mbuf *));
114 
115 /*
116  * ARCnet output routine.
117  * Encapsulate a packet of type family for the local net.
118  * Assumes that ifp is actually pointer to arccom structure.
119  */
120 static int
121 arc_output(ifp, m0, dst, rt0)
122 	struct ifnet *ifp;
123 	struct mbuf *m0;
124 	struct sockaddr *dst;
125 	struct rtentry *rt0;
126 {
127 	struct mbuf		*m, *m1, *mcopy;
128 	struct rtentry		*rt;
129 	struct arccom		*ac;
130 	struct arc_header	*ah;
131 	struct arphdr		*arph;
132 	int			s, error, newencoding;
133 	u_int8_t		atype, adst, myself;
134 	int			tfrags, sflag, fsflag, rsflag;
135 
136 	if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
137 		return(ENETDOWN); /* m, m1 aren't initialized yet */
138 
139 	error = newencoding = 0;
140 	ac = (struct arccom *)ifp;
141 	m = m0;
142 	mcopy = m1 = NULL;
143 
144 	myself = *LLADDR(ifp->if_sadl);
145 
146 	if ((rt = rt0)) {
147 		if ((rt->rt_flags & RTF_UP) == 0) {
148 			if ((rt0 = rt = rtalloc1(dst, 1)))
149 				rt->rt_refcnt--;
150 			else
151 				senderr(EHOSTUNREACH);
152 		}
153 		if (rt->rt_flags & RTF_GATEWAY) {
154 			if (rt->rt_gwroute == 0)
155 				goto lookup;
156 			if (((rt = rt->rt_gwroute)->rt_flags & RTF_UP) == 0) {
157 				rtfree(rt); rt = rt0;
158 			lookup: rt->rt_gwroute = rtalloc1(rt->rt_gateway, 1);
159 				if ((rt = rt->rt_gwroute) == 0)
160 					senderr(EHOSTUNREACH);
161 			}
162 		}
163 		if (rt->rt_flags & RTF_REJECT)
164 			if (rt->rt_rmx.rmx_expire == 0 ||
165 			    time.tv_sec < rt->rt_rmx.rmx_expire)
166 				senderr(rt == rt0 ? EHOSTDOWN : EHOSTUNREACH);
167 	}
168 
169 	switch (dst->sa_family) {
170 #ifdef INET
171 	case AF_INET:
172 
173 		/*
174 		 * For now, use the simple IP addr -> ARCnet addr mapping
175 		 */
176 		if (m->m_flags & (M_BCAST|M_MCAST))
177 			adst = arcbroadcastaddr; /* ARCnet broadcast address */
178 		else if (ifp->if_flags & IFF_NOARP)
179 			adst = ntohl(SIN(dst)->sin_addr.s_addr) & 0xFF;
180 		else if (!arpresolve(ifp, rt, m, dst, &adst))
181 			return 0;	/* not resolved yet */
182 
183 		/* If broadcasting on a simplex interface, loopback a copy */
184 		if ((m->m_flags & (M_BCAST|M_MCAST)) &&
185 		    (ifp->if_flags & IFF_SIMPLEX))
186 			mcopy = m_copy(m, 0, (int)M_COPYALL);
187 		if (ifp->if_flags & IFF_LINK0) {
188 			atype = ARCTYPE_IP;
189 			newencoding = 1;
190 		} else {
191 			atype = ARCTYPE_IP_OLD;
192 			newencoding = 0;
193 		}
194 		break;
195 
196 	case AF_ARP:
197 		arph = mtod(m, struct arphdr *);
198 		if (m->m_flags & M_BCAST)
199 			adst = arcbroadcastaddr;
200 		else
201 			adst = *ar_tha(arph);
202 
203 		arph->ar_hrd = htons(ARPHRD_ARCNET);
204 
205 		switch(ntohs(arph->ar_op)) {
206 
207 		case ARPOP_REVREQUEST:
208 		case ARPOP_REVREPLY:
209 			if (!(ifp->if_flags & IFF_LINK0)) {
210 				printf("%s: can't handle af%d\n",
211 				    ifp->if_xname, dst->sa_family);
212 				senderr(EAFNOSUPPORT);
213 			}
214 
215 			atype = htons(ARCTYPE_REVARP);
216 			newencoding = 1;
217 			break;
218 
219 		case ARPOP_REQUEST:
220 		case ARPOP_REPLY:
221 		default:
222 			if (ifp->if_flags & IFF_LINK0) {
223 				atype = htons(ARCTYPE_ARP);
224 				newencoding = 1;
225 			} else {
226 				atype = htons(ARCTYPE_ARP_OLD);
227 				newencoding = 0;
228 			}
229 		}
230 #ifdef ARCNET_ALLOW_BROKEN_ARP
231 		/*
232 		 * XXX It's not clear per RFC826 if this is needed, but
233 		 * "assigned numbers" say this is wrong.
234 		 * However, e.g., AmiTCP 3.0Beta used it... we make this
235 		 * switchable for emergency cases. Not perfect, but...
236 		 */
237 		if (ifp->if_flags & IFF_LINK2)
238 			arph->ar_pro = atype - 1;
239 #endif
240 		break;
241 #endif
242 #ifdef INET6
243 	case AF_INET6:
244 		if (!nd6_storelladdr(ifp, rt, m, dst, (u_char *)&adst))
245 			return(0); /* it must be impossible, but... */
246 		atype = htons(ARCTYPE_INET6);
247 		newencoding = 1;
248 		break;
249 #endif
250 
251 	case AF_UNSPEC:
252 		ah = (struct arc_header *)dst->sa_data;
253  		adst = ah->arc_dhost;
254 		atype = ah->arc_type;
255 		break;
256 
257 	default:
258 		printf("%s: can't handle af%d\n", ifp->if_xname,
259 		    dst->sa_family);
260 		senderr(EAFNOSUPPORT);
261 	}
262 
263 	if (mcopy)
264 		(void) looutput(ifp, mcopy, dst, rt);
265 
266 	/*
267 	 * Add local net header.  If no space in first mbuf,
268 	 * allocate another.
269 	 *
270 	 * For ARCnet, this is just symbolic. The header changes
271 	 * form and position on its way into the hardware and out of
272 	 * the wire.  At this point, it contains source, destination and
273 	 * packet type.
274 	 */
275 	if (newencoding) {
276 		++ac->ac_seqid; /* make the seqid unique */
277 
278 		tfrags = (m->m_pkthdr.len + 503) / 504;
279 		fsflag = 2 * tfrags - 3;
280 		sflag = 0;
281 		rsflag = fsflag;
282 
283 		while (sflag < fsflag) {
284 			/* we CAN'T have short packets here */
285 			m1 = m_split(m, 504, M_DONTWAIT);
286 			if (m1 == 0)
287 				senderr(ENOBUFS);
288 
289 			M_PREPEND(m, ARC_HDRNEWLEN, M_DONTWAIT);
290 			if (m == 0)
291 				senderr(ENOBUFS);
292 			ah = mtod(m, struct arc_header *);
293 			ah->arc_type = atype;
294 			ah->arc_dhost = adst;
295 			ah->arc_shost = myself;
296 			ah->arc_flag = rsflag;
297 			ah->arc_seqid = ac->ac_seqid;
298 
299 			s = splnet();
300 			/*
301 			 * Queue message on interface, and start output if
302 			 * interface not yet active.
303 			 */
304 			if (IF_QFULL(&ifp->if_snd)) {
305 				IF_DROP(&ifp->if_snd);
306 				splx(s);
307 				senderr(ENOBUFS);
308 			}
309 			ifp->if_obytes += m->m_pkthdr.len;
310 			IF_ENQUEUE(&ifp->if_snd, m);
311 			if ((ifp->if_flags & IFF_OACTIVE) == 0)
312 				(*ifp->if_start)(ifp);
313 			splx(s);
314 
315 			m = m1;
316 			sflag += 2;
317 			rsflag = sflag;
318 		}
319 		m1 = NULL;
320 
321 
322 		/* here we can have small, especially forbidden packets */
323 
324 		if ((m->m_pkthdr.len >=
325 		    ARC_MIN_FORBID_LEN - ARC_HDRNEWLEN + 2) &&
326 		    (m->m_pkthdr.len <=
327 		    ARC_MAX_FORBID_LEN - ARC_HDRNEWLEN + 2)) {
328 
329 			M_PREPEND(m, ARC_HDRNEWLEN_EXC, M_DONTWAIT);
330 			if (m == 0)
331 				senderr(ENOBUFS);
332 			ah = mtod(m, struct arc_header *);
333 			ah->arc_flag = 0xFF;
334 			ah->arc_seqid = 0xFFFF;
335 			ah->arc_type2 = atype;
336 			ah->arc_flag2 = sflag;
337 			ah->arc_seqid2 = ac->ac_seqid;
338 		} else {
339 			M_PREPEND(m, ARC_HDRNEWLEN, M_DONTWAIT);
340 			if (m == 0)
341 				senderr(ENOBUFS);
342 			ah = mtod(m, struct arc_header *);
343 			ah->arc_flag = sflag;
344 			ah->arc_seqid = ac->ac_seqid;
345 		}
346 
347 		ah->arc_dhost = adst;
348 		ah->arc_shost = myself;
349 		ah->arc_type = atype;
350 	} else {
351 		M_PREPEND(m, ARC_HDRLEN, M_DONTWAIT);
352 		if (m == 0)
353 			senderr(ENOBUFS);
354 		ah = mtod(m, struct arc_header *);
355 		ah->arc_type = atype;
356 		ah->arc_dhost = adst;
357 		ah->arc_shost = myself;
358 	}
359 	s = splnet();
360 	/*
361 	 * Queue message on interface, and start output if interface
362 	 * not yet active.
363 	 */
364 	if (IF_QFULL(&ifp->if_snd)) {
365 		IF_DROP(&ifp->if_snd);
366 		splx(s);
367 		senderr(ENOBUFS);
368 	}
369 	ifp->if_obytes += m->m_pkthdr.len;
370 	IF_ENQUEUE(&ifp->if_snd, m);
371 	if ((ifp->if_flags & IFF_OACTIVE) == 0)
372 		(*ifp->if_start)(ifp);
373 	splx(s);
374 
375 	return (error);
376 
377 bad:
378 	if (m1)
379 		m_freem(m1);
380 	if (m)
381 		m_freem(m);
382 	return (error);
383 }
384 
385 /*
386  * Defragmenter. Returns mbuf if last packet found, else
387  * NULL. frees imcoming mbuf as necessary.
388  */
389 
390 __inline struct mbuf *
391 arc_defrag(ifp, m)
392 	struct ifnet *ifp;
393 	struct mbuf *m;
394 {
395 	struct arc_header *ah, *ah1;
396 	struct arccom *ac;
397 	struct ac_frag *af;
398 	struct mbuf *m1;
399 	char *s;
400 	int newflen;
401 	u_char src,dst,typ;
402 
403 	ac = (struct arccom *)ifp;
404 
405 	if (m->m_len < ARC_HDRNEWLEN) {
406 		m = m_pullup(m, ARC_HDRNEWLEN);
407 		if (m == NULL) {
408 			++ifp->if_ierrors;
409 			return NULL;
410 		}
411 	}
412 
413 	ah = mtod(m, struct arc_header *);
414 	typ = ah->arc_type;
415 
416 	if (!arc_isphds(typ))
417 		return m;
418 
419 	src = ah->arc_shost;
420 	dst = ah->arc_dhost;
421 
422 	if (ah->arc_flag == 0xff) {
423 		m_adj(m, 4);
424 
425 		if (m->m_len < ARC_HDRNEWLEN) {
426 			m = m_pullup(m, ARC_HDRNEWLEN);
427 			if (m == NULL) {
428 				++ifp->if_ierrors;
429 				return NULL;
430 			}
431 		}
432 
433 		ah = mtod(m, struct arc_header *);
434 	}
435 
436 	af = &ac->ac_fragtab[src];
437 	m1 = af->af_packet;
438 	s = "debug code error";
439 
440 	if (ah->arc_flag & 1) {
441 		/*
442 		 * first fragment. We always initialize, which is
443 		 * about the right thing to do, as we only want to
444 		 * accept one fragmented packet per src at a time.
445 		 */
446 		if (m1 != NULL)
447 			m_freem(m1);
448 
449 		af->af_packet = m;
450 		m1 = m;
451 		af->af_maxflag = ah->arc_flag;
452 		af->af_lastseen = 0;
453 		af->af_seqid = ah->arc_seqid;
454 
455 		return NULL;
456 		/* notreached */
457 	} else {
458 		/* check for unfragmented packet */
459 		if (ah->arc_flag == 0)
460 			return m;
461 
462 		/* do we have a first packet from that src? */
463 		if (m1 == NULL) {
464 			s = "no first frag";
465 			goto outofseq;
466 		}
467 
468 		ah1 = mtod(m1, struct arc_header *);
469 
470 		if (ah->arc_seqid != ah1->arc_seqid) {
471 			s = "seqid differs";
472 			goto outofseq;
473 		}
474 
475 		if (typ != ah1->arc_type) {
476 			s = "type differs";
477 			goto outofseq;
478 		}
479 
480 		if (dst != ah1->arc_dhost) {
481 			s = "dest host differs";
482 			goto outofseq;
483 		}
484 
485 		/* typ, seqid and dst are ok here. */
486 
487 		if (ah->arc_flag == af->af_lastseen) {
488 			m_freem(m);
489 			return NULL;
490 		}
491 
492 		if (ah->arc_flag == af->af_lastseen + 2) {
493 			/* ok, this is next fragment */
494 			af->af_lastseen = ah->arc_flag;
495 			m_adj(m,ARC_HDRNEWLEN);
496 
497 			/*
498 			 * m_cat might free the first mbuf (with pkthdr)
499 			 * in 2nd chain; therefore:
500 			 */
501 
502 			newflen = m->m_pkthdr.len;
503 
504 			m_cat(m1,m);
505 
506 			m1->m_pkthdr.len += newflen;
507 
508 			/* is it the last one? */
509 			if (af->af_lastseen > af->af_maxflag) {
510 				af->af_packet = NULL;
511 				return(m1);
512 			} else
513 				return NULL;
514 		}
515 		s = "other reason";
516 		/* if all else fails, it is out of sequence, too */
517 	}
518 outofseq:
519 	if (m1) {
520 		m_freem(m1);
521 		af->af_packet = NULL;
522 	}
523 
524 	if (m)
525 		m_freem(m);
526 
527 	log(LOG_INFO,"%s: got out of seq. packet: %s\n",
528 	    ifp->if_xname, s);
529 
530 	return NULL;
531 }
532 
533 /*
534  * return 1 if Packet Header Definition Standard, else 0.
535  * For now: old IP, old ARP aren't obviously. Lacking correct information,
536  * we guess that besides new IP and new ARP also IPX and APPLETALK are PHDS.
537  * (Apple and Novell corporations were involved, among others, in PHDS work).
538  * Easiest is to assume that everybody else uses that, too.
539  */
540 int
541 arc_isphds(type)
542 	u_int8_t type;
543 {
544 	return (type != ARCTYPE_IP_OLD &&
545 		type != ARCTYPE_ARP_OLD &&
546 		type != ARCTYPE_DIAGNOSE);
547 }
548 
549 /*
550  * Process a received Arcnet packet;
551  * the packet is in the mbuf chain m with
552  * the ARCnet header.
553  */
554 static void
555 arc_input(ifp, m)
556 	struct ifnet *ifp;
557 	struct mbuf *m;
558 {
559 	struct arc_header *ah;
560 	struct ifqueue *inq;
561 	u_int8_t atype;
562 	int s;
563 	struct arphdr *arph;
564 
565 	if ((ifp->if_flags & IFF_UP) == 0) {
566 		m_freem(m);
567 		return;
568 	}
569 
570 	/* possibly defragment: */
571 	m = arc_defrag(ifp, m);
572 	if (m == NULL)
573 		return;
574 
575 	ah = mtod(m, struct arc_header *);
576 
577 	ifp->if_ibytes += m->m_pkthdr.len;
578 
579 	if (arcbroadcastaddr == ah->arc_dhost) {
580 		m->m_flags |= M_BCAST|M_MCAST;
581 		ifp->if_imcasts++;
582 	}
583 
584 	atype = ah->arc_type;
585 	switch (atype) {
586 #ifdef INET
587 	case ARCTYPE_IP:
588 		m_adj(m, ARC_HDRNEWLEN);
589 		schednetisr(NETISR_IP);
590 		inq = &ipintrq;
591 		break;
592 
593 	case ARCTYPE_IP_OLD:
594 		m_adj(m, ARC_HDRLEN);
595 		schednetisr(NETISR_IP);
596 		inq = &ipintrq;
597 		break;
598 
599 	case ARCTYPE_ARP:
600 		m_adj(m, ARC_HDRNEWLEN);
601 		schednetisr(NETISR_ARP);
602 		inq = &arpintrq;
603 #ifdef ARCNET_ALLOW_BROKEN_ARP
604 		mtod(m, struct arphdr *)->ar_pro = htons(ETHERTYPE_IP);
605 #endif
606 		break;
607 
608 	case ARCTYPE_ARP_OLD:
609 		m_adj(m, ARC_HDRLEN);
610 		schednetisr(NETISR_ARP);
611 		inq = &arpintrq;
612 		arph = mtod(m, struct arphdr *);
613 #ifdef ARCNET_ALLOW_BROKEN_ARP
614 		mtod(m, struct arphdr *)->ar_pro = htons(ETHERTYPE_IP);
615 #endif
616 		break;
617 #endif
618 #ifdef INET6
619 	case ARCTYPE_INET6:
620 		m_adj(m, ARC_HDRNEWLEN);
621 		schednetisr(NETISR_IPV6);
622 		inq = &ip6intrq;
623 		break;
624 #endif
625 	default:
626 		m_freem(m);
627 		return;
628 	}
629 
630 	s = splnet();
631 	if (IF_QFULL(inq)) {
632 		IF_DROP(inq);
633 		m_freem(m);
634 	} else
635 		IF_ENQUEUE(inq, m);
636 	splx(s);
637 }
638 
639 /*
640  * Convert Arcnet address to printable (loggable) representation.
641  */
642 static char digits[] = "0123456789abcdef";
643 char *
644 arc_sprintf(ap)
645 	u_int8_t *ap;
646 {
647 	static char arcbuf[3];
648 	char *cp = arcbuf;
649 
650 	*cp++ = digits[*ap >> 4];
651 	*cp++ = digits[*ap++ & 0xf];
652 	*cp   = 0;
653 	return (arcbuf);
654 }
655 
656 /*
657  * Register (new) link level address.
658  */
659 void
660 arc_storelladdr(ifp, lla)
661 	struct ifnet *ifp;
662 	u_int8_t lla;
663 {
664 
665 	*(LLADDR(ifp->if_sadl)) = lla;
666 	ifp->if_mtu = ARC_PHDS_MAXMTU;
667 }
668 
669 /*
670  * Perform common duties while attaching to interface list
671  */
672 void
673 arc_ifattach(ifp, lla)
674 	struct ifnet *ifp;
675 	u_int8_t lla;
676 {
677 	struct arccom *ac;
678 
679 	ifp->if_type = IFT_ARCNET;
680 	ifp->if_addrlen = 1;
681 	ifp->if_hdrlen = ARC_HDRLEN;
682 	ifp->if_dlt = DLT_ARCNET;
683 	if (ifp->if_flags & IFF_BROADCAST)
684 		ifp->if_flags |= IFF_MULTICAST|IFF_ALLMULTI;
685 	if (ifp->if_flags & IFF_LINK0 && arc_ipmtu > ARC_PHDS_MAXMTU)
686 		log(LOG_ERR,
687 		    "%s: arc_ipmtu is %d, but must not exceed %d",
688 		    ifp->if_xname, arc_ipmtu, ARC_PHDS_MAXMTU);
689 
690 	ifp->if_output = arc_output;
691 	ifp->if_input = arc_input;
692 	ac = (struct arccom *)ifp;
693 	ac->ac_seqid = (time.tv_sec) & 0xFFFF; /* try to make seqid unique */
694 	if (lla == 0) {
695 		/* XXX this message isn't entirely clear, to me -- cgd */
696 		log(LOG_ERR,"%s: link address 0 reserved for broadcasts.  Please change it and ifconfig %s down up\n",
697 		   ifp->if_xname, ifp->if_xname);
698 	}
699 	if_attach(ifp);
700 	if_alloc_sadl(ifp);
701 	arc_storelladdr(ifp, lla);
702 
703 	ifp->if_broadcastaddr = &arcbroadcastaddr;
704 
705 #if NBPFILTER > 0
706 	bpfattach(ifp, DLT_ARCNET, ARC_HDRLEN);
707 #endif
708 }
709