xref: /netbsd-src/sys/net/if_arcsubr.c (revision 89c5a767f8fc7a4633b2d409966e2becbb98ff92)
1 /*	$NetBSD: if_arcsubr.c,v 1.29 1999/12/20 20:27:14 frueauf 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 <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
45 #include <sys/malloc.h>
46 #include <sys/mbuf.h>
47 #include <sys/protosw.h>
48 #include <sys/socket.h>
49 #include <sys/ioctl.h>
50 #include <sys/errno.h>
51 #include <sys/syslog.h>
52 
53 #include <machine/cpu.h>
54 
55 #include <net/if.h>
56 #include <net/netisr.h>
57 #include <net/route.h>
58 #include <net/if_dl.h>
59 #include <net/if_types.h>
60 #include <net/if_arc.h>
61 #include <net/if_arp.h>
62 #include <net/if_ether.h>
63 
64 #ifdef INET
65 #include <netinet/in.h>
66 #include <netinet/in_var.h>
67 #include <netinet/if_inarp.h>
68 #endif
69 
70 #ifdef INET6
71 #ifndef INET
72 #include <netinet/in.h>
73 #endif
74 #include <netinet6/in6_var.h>
75 #include <netinet6/nd6.h>
76 #include <netinet6/in6_ifattach.h>
77 #endif
78 
79 #define ARCNET_ALLOW_BROKEN_ARP
80 
81 #ifndef ARC_IPMTU
82 #define ARC_IPMTU	1500
83 #endif
84 
85 static struct mbuf *arc_defrag __P((struct ifnet *, struct mbuf *));
86 
87 /*
88  * RC1201 requires us to have this configurable. We have it only per
89  * machine at the moment... there is no generic "set mtu" ioctl, AFAICS.
90  * Anyway, it is possible to binpatch this or set it per kernel config
91  * option.
92  */
93 #if ARC_IPMTU > 60480
94 ERROR: The arc_ipmtu is ARC_IPMTU, but must not exceed 60480.
95 #endif
96 int arc_ipmtu = ARC_IPMTU;
97 u_int8_t  arcbroadcastaddr = 0;
98 
99 #define senderr(e) { error = (e); goto bad;}
100 #define SIN(s) ((struct sockaddr_in *)s)
101 
102 static	int arc_output __P((struct ifnet *, struct mbuf *,
103 	    struct sockaddr *, struct rtentry *));
104 static	void arc_input __P((struct ifnet *, struct mbuf *));
105 
106 /*
107  * ARCnet output routine.
108  * Encapsulate a packet of type family for the local net.
109  * Assumes that ifp is actually pointer to arccom structure.
110  */
111 static int
112 arc_output(ifp, m0, dst, rt0)
113 	register struct ifnet *ifp;
114 	struct mbuf *m0;
115 	struct sockaddr *dst;
116 	struct rtentry *rt0;
117 {
118 	struct mbuf		*m, *m1, *mcopy;
119 	struct rtentry		*rt;
120 	struct arccom		*ac;
121 	struct arc_header	*ah;
122 	struct arphdr		*arph;
123 	int			s, error, newencoding;
124 	u_int8_t		atype, adst, myself;
125 	int			tfrags, sflag, fsflag, rsflag;
126 
127 	if ((ifp->if_flags & (IFF_UP|IFF_RUNNING)) != (IFF_UP|IFF_RUNNING))
128 		return(ENETDOWN); /* m, m1 aren't initialized yet */
129 
130 	error = newencoding = 0;
131 	ac = (struct arccom *)ifp;
132 	m = m0;
133 	mcopy = m1 = NULL;
134 
135 	myself = *LLADDR(ifp->if_sadl);
136 
137 	ifp->if_lastchange = time;
138 	if ((rt = rt0)) {
139 		if ((rt->rt_flags & RTF_UP) == 0) {
140 			if ((rt0 = rt = rtalloc1(dst, 1)))
141 				rt->rt_refcnt--;
142 			else
143 				senderr(EHOSTUNREACH);
144 		}
145 		if (rt->rt_flags & RTF_GATEWAY) {
146 			if (rt->rt_gwroute == 0)
147 				goto lookup;
148 			if (((rt = rt->rt_gwroute)->rt_flags & RTF_UP) == 0) {
149 				rtfree(rt); rt = rt0;
150 			lookup: rt->rt_gwroute = rtalloc1(rt->rt_gateway, 1);
151 				if ((rt = rt->rt_gwroute) == 0)
152 					senderr(EHOSTUNREACH);
153 			}
154 		}
155 		if (rt->rt_flags & RTF_REJECT)
156 			if (rt->rt_rmx.rmx_expire == 0 ||
157 			    time.tv_sec < rt->rt_rmx.rmx_expire)
158 				senderr(rt == rt0 ? EHOSTDOWN : EHOSTUNREACH);
159 	}
160 
161 	switch (dst->sa_family) {
162 #ifdef INET
163 	case AF_INET:
164 
165 		/*
166 		 * For now, use the simple IP addr -> ARCnet addr mapping
167 		 */
168 		if (m->m_flags & (M_BCAST|M_MCAST))
169 			adst = arcbroadcastaddr; /* ARCnet broadcast address */
170 		else if (ifp->if_flags & IFF_NOARP)
171 			adst = ntohl(SIN(dst)->sin_addr.s_addr) & 0xFF;
172 		else if (!arpresolve(ifp, rt, m, dst, &adst))
173 			return 0;	/* not resolved yet */
174 
175 		/* If broadcasting on a simplex interface, loopback a copy */
176 		if ((m->m_flags & (M_BCAST|M_MCAST)) &&
177 		    (ifp->if_flags & IFF_SIMPLEX))
178 			mcopy = m_copy(m, 0, (int)M_COPYALL);
179 		if (ifp->if_flags & IFF_LINK0) {
180 			atype = ARCTYPE_IP;
181 			newencoding = 1;
182 		} else {
183 			atype = ARCTYPE_IP_OLD;
184 			newencoding = 0;
185 		}
186 		break;
187 
188 	case AF_ARP:
189 		arph = mtod(m, struct arphdr *);
190 		if (m->m_flags & M_BCAST)
191 			adst = arcbroadcastaddr;
192 		else
193 			adst = *ar_tha(arph);
194 
195 		arph->ar_hrd = htons(ARPHRD_ARCNET);
196 
197 		switch(ntohs(arph->ar_op)) {
198 
199 		case ARPOP_REVREQUEST:
200 		case ARPOP_REVREPLY:
201 			if (!(ifp->if_flags & IFF_LINK0)) {
202 				printf("%s: can't handle af%d\n",
203 				    ifp->if_xname, dst->sa_family);
204 				senderr(EAFNOSUPPORT);
205 			}
206 
207 			atype = htons(ARCTYPE_REVARP);
208 			newencoding = 1;
209 			break;
210 
211 		case ARPOP_REQUEST:
212 		case ARPOP_REPLY:
213 		default:
214 			if (ifp->if_flags & IFF_LINK0) {
215 				atype = htons(ARCTYPE_ARP);
216 				newencoding = 1;
217 			} else {
218 				atype = htons(ARCTYPE_ARP_OLD);
219 				newencoding = 0;
220 			}
221 		}
222 #ifdef ARCNET_ALLOW_BROKEN_ARP
223 		/*
224 		 * XXX It's not clear per RFC826 if this is needed, but
225 		 * "assigned numbers" say this is wrong.
226 		 * However, e.g., AmiTCP 3.0Beta used it... we make this
227 		 * switchable for emergency cases. Not perfect, but...
228 		 */
229 		if (ifp->if_flags & IFF_LINK2)
230 			arph->ar_pro = atype - 1;
231 #endif
232 		break;
233 #endif
234 #ifdef INET6
235 	case AF_INET6:
236 #ifdef OLDIP6OUTPUT
237 		if (!nd6_resolve(ifp, rt, m, dst, (u_char *)&adst))
238 			return(0);	/* if not yet resolves */
239 #else
240 		if (!nd6_storelladdr(ifp, rt, m, dst, (u_char *)&adst))
241 			return(0); /* it must be impossible, but... */
242 #endif /* OLDIP6OUTPUT */
243 		atype = htons(ARCTYPE_INET6);
244 		newencoding = 1;
245 		break;
246 #endif
247 
248 	case AF_UNSPEC:
249 		ah = (struct arc_header *)dst->sa_data;
250  		adst = ah->arc_dhost;
251 		atype = ah->arc_type;
252 		break;
253 
254 	default:
255 		printf("%s: can't handle af%d\n", ifp->if_xname,
256 		    dst->sa_family);
257 		senderr(EAFNOSUPPORT);
258 	}
259 
260 	if (mcopy)
261 		(void) looutput(ifp, mcopy, dst, rt);
262 
263 	/*
264 	 * Add local net header.  If no space in first mbuf,
265 	 * allocate another.
266 	 *
267 	 * For ARCnet, this is just symbolic. The header changes
268 	 * form and position on its way into the hardware and out of
269 	 * the wire.  At this point, it contains source, destination and
270 	 * packet type.
271 	 */
272 	if (newencoding) {
273 		++ac->ac_seqid; /* make the seqid unique */
274 
275 		tfrags = (m->m_pkthdr.len + 503) / 504;
276 		fsflag = 2 * tfrags - 3;
277 		sflag = 0;
278 		rsflag = fsflag;
279 
280 		while (sflag < fsflag) {
281 			/* we CAN'T have short packets here */
282 			m1 = m_split(m, 504, M_DONTWAIT);
283 			if (m1 == 0)
284 				senderr(ENOBUFS);
285 
286 			M_PREPEND(m, ARC_HDRNEWLEN, M_DONTWAIT);
287 			if (m == 0)
288 				senderr(ENOBUFS);
289 			ah = mtod(m, struct arc_header *);
290 			ah->arc_type = atype;
291 			ah->arc_dhost = adst;
292 			ah->arc_shost = myself;
293 			ah->arc_flag = rsflag;
294 			ah->arc_seqid = ac->ac_seqid;
295 
296 			s = splimp();
297 			/*
298 			 * Queue message on interface, and start output if
299 			 * interface not yet active.
300 			 */
301 			if (IF_QFULL(&ifp->if_snd)) {
302 				IF_DROP(&ifp->if_snd);
303 				splx(s);
304 				senderr(ENOBUFS);
305 			}
306 			ifp->if_obytes += m->m_pkthdr.len;
307 			IF_ENQUEUE(&ifp->if_snd, m);
308 			if ((ifp->if_flags & IFF_OACTIVE) == 0)
309 				(*ifp->if_start)(ifp);
310 			splx(s);
311 
312 			m = m1;
313 			sflag += 2;
314 			rsflag = sflag;
315 		}
316 		m1 = NULL;
317 
318 
319 		/* here we can have small, especially forbidden packets */
320 
321 		if ((m->m_pkthdr.len >=
322 		    ARC_MIN_FORBID_LEN - ARC_HDRNEWLEN + 2) &&
323 		    (m->m_pkthdr.len <=
324 		    ARC_MAX_FORBID_LEN - ARC_HDRNEWLEN + 2)) {
325 
326 			M_PREPEND(m, ARC_HDRNEWLEN_EXC, M_DONTWAIT);
327 			if (m == 0)
328 				senderr(ENOBUFS);
329 			ah = mtod(m, struct arc_header *);
330 			ah->arc_flag = 0xFF;
331 			ah->arc_seqid = 0xFFFF;
332 			ah->arc_type2 = atype;
333 			ah->arc_flag2 = sflag;
334 			ah->arc_seqid2 = ac->ac_seqid;
335 		} else {
336 			M_PREPEND(m, ARC_HDRNEWLEN, M_DONTWAIT);
337 			if (m == 0)
338 				senderr(ENOBUFS);
339 			ah = mtod(m, struct arc_header *);
340 			ah->arc_flag = sflag;
341 			ah->arc_seqid = ac->ac_seqid;
342 		}
343 
344 		ah->arc_dhost = adst;
345 		ah->arc_shost = myself;
346 		ah->arc_type = atype;
347 	} else {
348 		M_PREPEND(m, ARC_HDRLEN, M_DONTWAIT);
349 		if (m == 0)
350 			senderr(ENOBUFS);
351 		ah = mtod(m, struct arc_header *);
352 		ah->arc_type = atype;
353 		ah->arc_dhost = adst;
354 		ah->arc_shost = myself;
355 	}
356 	s = splimp();
357 	/*
358 	 * Queue message on interface, and start output if interface
359 	 * not yet active.
360 	 */
361 	if (IF_QFULL(&ifp->if_snd)) {
362 		IF_DROP(&ifp->if_snd);
363 		splx(s);
364 		senderr(ENOBUFS);
365 	}
366 	ifp->if_obytes += m->m_pkthdr.len;
367 	IF_ENQUEUE(&ifp->if_snd, m);
368 	if ((ifp->if_flags & IFF_OACTIVE) == 0)
369 		(*ifp->if_start)(ifp);
370 	splx(s);
371 
372 	return (error);
373 
374 bad:
375 	if (m1)
376 		m_freem(m1);
377 	if (m)
378 		m_freem(m);
379 	return (error);
380 }
381 
382 /*
383  * Defragmenter. Returns mbuf if last packet found, else
384  * NULL. frees imcoming mbuf as necessary.
385  */
386 
387 __inline struct mbuf *
388 arc_defrag(ifp, m)
389 	struct ifnet *ifp;
390 	struct mbuf *m;
391 {
392 	struct arc_header *ah, *ah1;
393 	struct arccom *ac;
394 	struct ac_frag *af;
395 	struct mbuf *m1;
396 	char *s;
397 	int newflen;
398 	u_char src,dst,typ;
399 
400 	ac = (struct arccom *)ifp;
401 
402 	if (m->m_len < ARC_HDRNEWLEN) {
403 		m = m_pullup(m, ARC_HDRNEWLEN);
404 		if (m == NULL) {
405 			++ifp->if_ierrors;
406 			return NULL;
407 		}
408 	}
409 
410 	ah = mtod(m, struct arc_header *);
411 	typ = ah->arc_type;
412 
413 	if (!arc_isphds(typ))
414 		return m;
415 
416 	src = ah->arc_shost;
417 	dst = ah->arc_dhost;
418 
419 	if (ah->arc_flag == 0xff) {
420 		m_adj(m, 4);
421 
422 		if (m->m_len < ARC_HDRNEWLEN) {
423 			m = m_pullup(m, ARC_HDRNEWLEN);
424 			if (m == NULL) {
425 				++ifp->if_ierrors;
426 				return NULL;
427 			}
428 		}
429 
430 		ah = mtod(m, struct arc_header *);
431 	}
432 
433 	af = &ac->ac_fragtab[src];
434 	m1 = af->af_packet;
435 	s = "debug code error";
436 
437 	if (ah->arc_flag & 1) {
438 		/*
439 		 * first fragment. We always initialize, which is
440 		 * about the right thing to do, as we only want to
441 		 * accept one fragmented packet per src at a time.
442 		 */
443 		if (m1 != NULL)
444 			m_freem(m1);
445 
446 		af->af_packet = m;
447 		m1 = m;
448 		af->af_maxflag = ah->arc_flag;
449 		af->af_lastseen = 0;
450 		af->af_seqid = ah->arc_seqid;
451 
452 		return NULL;
453 		/* notreached */
454 	} else {
455 		/* check for unfragmented packet */
456 		if (ah->arc_flag == 0)
457 			return m;
458 
459 		/* do we have a first packet from that src? */
460 		if (m1 == NULL) {
461 			s = "no first frag";
462 			goto outofseq;
463 		}
464 
465 		ah1 = mtod(m1, struct arc_header *);
466 
467 		if (ah->arc_seqid != ah1->arc_seqid) {
468 			s = "seqid differs";
469 			goto outofseq;
470 		}
471 
472 		if (typ != ah1->arc_type) {
473 			s = "type differs";
474 			goto outofseq;
475 		}
476 
477 		if (dst != ah1->arc_dhost) {
478 			s = "dest host differs";
479 			goto outofseq;
480 		}
481 
482 		/* typ, seqid and dst are ok here. */
483 
484 		if (ah->arc_flag == af->af_lastseen) {
485 			m_freem(m);
486 			return NULL;
487 		}
488 
489 		if (ah->arc_flag == af->af_lastseen + 2) {
490 			/* ok, this is next fragment */
491 			af->af_lastseen = ah->arc_flag;
492 			m_adj(m,ARC_HDRNEWLEN);
493 
494 			/*
495 			 * m_cat might free the first mbuf (with pkthdr)
496 			 * in 2nd chain; therefore:
497 			 */
498 
499 			newflen = m->m_pkthdr.len;
500 
501 			m_cat(m1,m);
502 
503 			m1->m_pkthdr.len += newflen;
504 
505 			/* is it the last one? */
506 			if (af->af_lastseen > af->af_maxflag) {
507 				af->af_packet = NULL;
508 				return(m1);
509 			} else
510 				return NULL;
511 		}
512 		s = "other reason";
513 		/* if all else fails, it is out of sequence, too */
514 	}
515 outofseq:
516 	if (m1) {
517 		m_freem(m1);
518 		af->af_packet = NULL;
519 	}
520 
521 	if (m)
522 		m_freem(m);
523 
524 	log(LOG_INFO,"%s: got out of seq. packet: %s\n",
525 	    ifp->if_xname, s);
526 
527 	return NULL;
528 }
529 
530 /*
531  * return 1 if Packet Header Definition Standard, else 0.
532  * For now: old IP, old ARP aren't obviously. Lacking correct information,
533  * we guess that besides new IP and new ARP also IPX and APPLETALK are PHDS.
534  * (Apple and Novell corporations were involved, among others, in PHDS work).
535  * Easiest is to assume that everybody else uses that, too.
536  */
537 int
538 arc_isphds(type)
539 	u_int8_t type;
540 {
541 	return (type != ARCTYPE_IP_OLD &&
542 		type != ARCTYPE_ARP_OLD &&
543 		type != ARCTYPE_DIAGNOSE);
544 }
545 
546 /*
547  * Process a received Arcnet packet;
548  * the packet is in the mbuf chain m with
549  * the ARCnet header.
550  */
551 static void
552 arc_input(ifp, m)
553 	struct ifnet *ifp;
554 	struct mbuf *m;
555 {
556 	register struct arc_header *ah;
557 	register struct ifqueue *inq;
558 	u_int8_t atype;
559 	int s;
560 	struct arphdr *arph;
561 
562 	if ((ifp->if_flags & IFF_UP) == 0) {
563 		m_freem(m);
564 		return;
565 	}
566 
567 	/* possibly defragment: */
568 	m = arc_defrag(ifp, m);
569 	if (m == NULL)
570 		return;
571 
572 	ah = mtod(m, struct arc_header *);
573 
574 	ifp->if_lastchange = time;
575 	ifp->if_ibytes += m->m_pkthdr.len;
576 
577 	if (arcbroadcastaddr == ah->arc_dhost) {
578 		m->m_flags |= M_BCAST|M_MCAST;
579 		ifp->if_imcasts++;
580 	}
581 
582 	atype = ah->arc_type;
583 	switch (atype) {
584 #ifdef INET
585 	case ARCTYPE_IP:
586 		m_adj(m, ARC_HDRNEWLEN);
587 		schednetisr(NETISR_IP);
588 		inq = &ipintrq;
589 		break;
590 
591 	case ARCTYPE_IP_OLD:
592 		m_adj(m, ARC_HDRLEN);
593 		schednetisr(NETISR_IP);
594 		inq = &ipintrq;
595 		break;
596 
597 	case ARCTYPE_ARP:
598 		m_adj(m, ARC_HDRNEWLEN);
599 		schednetisr(NETISR_ARP);
600 		inq = &arpintrq;
601 #ifdef ARCNET_ALLOW_BROKEN_ARP
602 		mtod(m, struct arphdr *)->ar_pro = htons(ETHERTYPE_IP);
603 #endif
604 		break;
605 
606 	case ARCTYPE_ARP_OLD:
607 		m_adj(m, ARC_HDRLEN);
608 		schednetisr(NETISR_ARP);
609 		inq = &arpintrq;
610 		arph = mtod(m, struct arphdr *);
611 #ifdef ARCNET_ALLOW_BROKEN_ARP
612 		mtod(m, struct arphdr *)->ar_pro = htons(ETHERTYPE_IP);
613 #endif
614 		break;
615 #endif
616 #ifdef INET6
617 	case ARCTYPE_INET6:
618 		m_adj(m, ARC_HDRNEWLEN);
619 		schednetisr(NETISR_IPV6);
620 		inq = &ip6intrq;
621 		break;
622 #endif
623 	default:
624 		m_freem(m);
625 		return;
626 	}
627 
628 	s = splimp();
629 	if (IF_QFULL(inq)) {
630 		IF_DROP(inq);
631 		m_freem(m);
632 	} else
633 		IF_ENQUEUE(inq, m);
634 	splx(s);
635 }
636 
637 /*
638  * Convert Arcnet address to printable (loggable) representation.
639  */
640 static char digits[] = "0123456789abcdef";
641 char *
642 arc_sprintf(ap)
643 	register u_int8_t *ap;
644 {
645 	static char arcbuf[3];
646 	register char *cp = arcbuf;
647 
648 	*cp++ = digits[*ap >> 4];
649 	*cp++ = digits[*ap++ & 0xf];
650 	*cp   = 0;
651 	return (arcbuf);
652 }
653 
654 /*
655  * Register (new) link level address.
656  */
657 void
658 arc_storelladdr(ifp, lla)
659 	struct ifnet *ifp;
660 	u_int8_t lla;
661 {
662 	register struct sockaddr_dl *sdl;
663 	if ((sdl = ifp->if_sadl) &&
664 	   sdl->sdl_family == AF_LINK) {
665 		sdl->sdl_type = IFT_ARCNET;
666 		sdl->sdl_alen = ifp->if_addrlen;
667 		*(LLADDR(sdl)) = lla;
668 	}
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 	register struct ifnet *ifp;
678 	u_int8_t lla;
679 {
680 	register struct arccom *ac;
681 
682 	ifp->if_type = IFT_ARCNET;
683 	ifp->if_addrlen = 1;
684 	ifp->if_hdrlen = ARC_HDRLEN;
685 	if (ifp->if_flags & IFF_BROADCAST)
686 		ifp->if_flags |= IFF_MULTICAST|IFF_ALLMULTI;
687 	if (ifp->if_flags & IFF_LINK0 && arc_ipmtu > ARC_PHDS_MAXMTU)
688 		log(LOG_ERR,
689 		    "%s: arc_ipmtu is %d, but must not exceed %d",
690 		    ifp->if_xname, arc_ipmtu, ARC_PHDS_MAXMTU);
691 
692 	ifp->if_output = arc_output;
693 	ifp->if_input = arc_input;
694 	ac = (struct arccom *)ifp;
695 	ac->ac_seqid = (time.tv_sec) & 0xFFFF; /* try to make seqid unique */
696 	if (lla == 0) {
697 		/* XXX this message isn't entirely clear, to me -- cgd */
698 		log(LOG_ERR,"%s: link address 0 reserved for broadcasts.  Please change it and ifconfig %s down up\n",
699 		   ifp->if_xname, ifp->if_xname);
700 	}
701 	if_attach(ifp);
702 	arc_storelladdr(ifp, lla);
703 
704 	ifp->if_broadcastaddr = &arcbroadcastaddr;
705 #ifdef INET6
706 	in6_ifattach_getifid(ifp);
707 #endif
708 }
709