18778176494c228fbd4f3f9dba7f43cc37726fdd
[akaros.git] / kern / src / net / ethermedium.c
1 #include "u.h"
2 #include "../port/lib.h"
3 #include "mem.h"
4 #include "dat.h"
5 #include "fns.h"
6 #include "../port/error.h"
7
8 #include "ip.h"
9 #include "ipv6.h"
10 #include "kernel.h"
11
12 typedef struct Etherhdr Etherhdr;
13 struct Etherhdr
14 {
15         uchar   d[6];
16         uchar   s[6];
17         uchar   t[2];
18 };
19
20 static uchar ipbroadcast[IPaddrlen] = {
21         0xff,0xff,0xff,0xff,  
22         0xff,0xff,0xff,0xff,  
23         0xff,0xff,0xff,0xff,  
24         0xff,0xff,0xff,0xff,
25 };
26
27 static uchar etherbroadcast[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
28
29 static void     etherread4(void *a);
30 static void     etherread6(void *a);
31 static void     etherbind(Ipifc *ifc, int argc, char **argv);
32 static void     etherunbind(Ipifc *ifc);
33 static void     etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip);
34 static void     etheraddmulti(Ipifc *ifc, uchar *a, uchar *ia);
35 static void     etherremmulti(Ipifc *ifc, uchar *a, uchar *ia);
36 static Block*   multicastarp(Fs *f, Arpent *a, Medium*, uchar *mac);
37 static void     sendarp(Ipifc *ifc, Arpent *a);
38 static void     sendgarp(Ipifc *ifc, uchar*);
39 static int      multicastea(uchar *ea, uchar *ip);
40 static void     recvarpproc(void*);
41 static void     resolveaddr6(Ipifc *ifc, Arpent *a);
42 static void     etherpref2addr(uchar *pref, uchar *ea);
43
44 Medium ethermedium =
45 {
46 .name=          "ether",
47 .hsize=         14,
48 .mintu=         60,
49 .maxtu=         1514,
50 .maclen=        6,
51 .bind=          etherbind,
52 .unbind=        etherunbind,
53 .bwrite=        etherbwrite,
54 .addmulti=      etheraddmulti,
55 .remmulti=      etherremmulti,
56 .ares=          arpenter,
57 .areg=          sendgarp,
58 .pref2addr=     etherpref2addr,
59 };
60
61 Medium gbemedium =
62 {
63 .name=          "gbe",
64 .hsize=         14,
65 .mintu=         60,
66 .maxtu=         9014,
67 .maclen=        6,
68 .bind=          etherbind,
69 .unbind=        etherunbind,
70 .bwrite=        etherbwrite,
71 .addmulti=      etheraddmulti,
72 .remmulti=      etherremmulti,
73 .ares=          arpenter,
74 .areg=          sendgarp,
75 .pref2addr=     etherpref2addr,
76 };
77
78 typedef struct  Etherrock Etherrock;
79 struct Etherrock
80 {
81         Fs      *f;             /* file system we belong to */
82         Proc    *arpp;          /* arp process */
83         Proc    *read4p;        /* reading process (v4)*/
84         Proc    *read6p;        /* reading process (v6)*/
85         Chan    *mchan4;        /* Data channel for v4 */
86         Chan    *achan;         /* Arp channel */
87         Chan    *cchan4;        /* Control channel for v4 */
88         Chan    *mchan6;        /* Data channel for v6 */
89         Chan    *cchan6;        /* Control channel for v6 */
90 };
91
92 /*
93  *  ethernet arp request
94  */
95 enum
96 {
97         ETARP           = 0x0806,
98         ETIP4           = 0x0800,
99         ETIP6           = 0x86DD,
100         ARPREQUEST      = 1,
101         ARPREPLY        = 2,
102 };
103
104 typedef struct Etherarp Etherarp;
105 struct Etherarp
106 {
107         uchar   d[6];
108         uchar   s[6];
109         uchar   type[2];
110         uchar   hrd[2];
111         uchar   pro[2];
112         uchar   hln;
113         uchar   pln;
114         uchar   op[2];
115         uchar   sha[6];
116         uchar   spa[4];
117         uchar   tha[6];
118         uchar   tpa[4];
119 };
120
121 static char *nbmsg = "nonblocking";
122
123 /*
124  *  called to bind an IP ifc to an ethernet device
125  *  called with ifc wlock'd
126  */
127 static void
128 etherbind(Ipifc *ifc, int argc, char **argv)
129 {
130         Chan *mchan4, *cchan4, *achan, *mchan6, *cchan6;
131         char addr[Maxpath];     //char addr[2*KNAMELEN];
132         char dir[Maxpath];      //char dir[2*KNAMELEN];
133         char *buf;
134         int fd, cfd, n;
135         char *ptr;
136         Etherrock *er;
137
138         if(argc < 2)
139                 error(Ebadarg);
140
141         mchan4 = cchan4 = achan = mchan6 = cchan6 = nil;
142         buf = nil;
143         if(waserror()){
144                 if(mchan4 != nil)
145                         cclose(mchan4);
146                 if(cchan4 != nil)
147                         cclose(cchan4);
148                 if(achan != nil)
149                         cclose(achan);
150                 if(mchan6 != nil)
151                         cclose(mchan6);
152                 if(cchan6 != nil)
153                         cclose(cchan6);
154                 if(buf != nil)
155                         free(buf);
156                 nexterror(); 
157         }
158
159         /*
160          *  open ip converstation
161          *
162          *  the dial will fail if the type is already open on
163          *  this device.
164          */
165         snprint(addr, sizeof(addr), "%s!0x800", argv[2]);
166         fd = kdial(addr, nil, dir, &cfd);
167         if(fd < 0)
168                 errorf("dial 0x800 failed: %s", up->env->errstr);
169         mchan4 = commonfdtochan(fd, ORDWR, 0, 1);
170         cchan4 = commonfdtochan(cfd, ORDWR, 0, 1);
171         kclose(fd);
172         kclose(cfd);
173
174         /*
175          *  make it non-blocking
176          */
177         devtab[cchan4->type]->write(cchan4, nbmsg, strlen(nbmsg), 0);
178
179         /*
180          *  get mac address and speed
181          */
182         snprint(addr, sizeof(addr), "%s/stats", dir);
183         fd = kopen(addr, OREAD);
184         if(fd < 0)
185                 errorf("can't open ether stats: %s", up->env->errstr);
186
187         buf = smalloc(512);
188         n = kread(fd, buf, 511);
189         kclose(fd);
190         if(n <= 0)
191                 error(Eio);
192         buf[n] = 0;
193
194         ptr = strstr(buf, "addr: ");
195         if(!ptr)
196                 error(Eio);
197         ptr += 6;
198         parsemac(ifc->mac, ptr, 6);
199
200         ptr = strstr(buf, "mbps: ");
201         if(ptr){
202                 ptr += 6;
203                 ifc->mbps = atoi(ptr);
204         } else
205                 ifc->mbps = 100;
206
207         /*
208          *  open arp conversation
209          */
210         snprint(addr, sizeof(addr), "%s!0x806", argv[2]);
211         fd = kdial(addr, nil, nil, nil);
212         if(fd < 0)
213                 errorf("dial 0x806 failed: %s", up->env->errstr);
214         achan = commonfdtochan(fd, ORDWR, 0, 1);
215         kclose(fd);
216
217         /*
218          *  open ip conversation
219          *
220          *  the dial will fail if the type is already open on
221          *  this device.
222          */
223         snprint(addr, sizeof(addr), "%s!0x86DD", argv[2]);
224         fd = kdial(addr, nil, dir, &cfd);
225         if(fd < 0)
226                 errorf("dial 0x86DD failed: %s", up->env->errstr);
227         mchan6 = commonfdtochan(fd, ORDWR, 0, 1);
228         cchan6 = commonfdtochan(cfd, ORDWR, 0, 1);
229         kclose(fd);
230         kclose(cfd);
231
232         /*
233          *  make it non-blocking
234          */
235         devtab[cchan6->type]->write(cchan6, nbmsg, strlen(nbmsg), 0);
236
237         er = smalloc(sizeof(*er));
238         er->mchan4 = mchan4;
239         er->cchan4 = cchan4;
240         er->achan = achan;
241         er->mchan6 = mchan6;
242         er->cchan6 = cchan6;
243         er->f = ifc->conv->p->f;
244         ifc->arg = er;
245
246         free(buf);
247         poperror();
248
249         kproc("etherread4", etherread4, ifc, 0);
250         kproc("recvarpproc", recvarpproc, ifc, 0);
251         kproc("etherread6", etherread6, ifc, 0);
252 }
253
254 /*
255  *  called with ifc wlock'd
256  */
257 static void
258 etherunbind(Ipifc *ifc)
259 {
260         Etherrock *er = ifc->arg;
261
262         if(er->read4p)
263                 postnote(er->read4p, 1, "unbind", 0);
264         if(er->read6p)
265                 postnote(er->read6p, 1, "unbind", 0);
266         if(er->arpp)
267                 postnote(er->arpp, 1, "unbind", 0);
268
269         /* wait for readers to die */
270         while(er->arpp != 0 || er->read4p != 0 || er->read6p != 0)
271                 tsleep(&up->sleep, return0, 0, 300);
272
273         if(er->mchan4 != nil)
274                 cclose(er->mchan4);
275         if(er->achan != nil)
276                 cclose(er->achan);
277         if(er->cchan4 != nil)
278                 cclose(er->cchan4);
279         if(er->mchan6 != nil)
280                 cclose(er->mchan6);
281         if(er->cchan6 != nil)
282                 cclose(er->cchan6);
283
284         free(er);
285 }
286
287 /*
288  *  called by ipoput with a single block to write with ifc rlock'd
289  */
290 static void
291 etherbwrite(Ipifc *ifc, Block *bp, int version, uchar *ip)
292 {
293         Etherhdr *eh;
294         Arpent *a;
295         uchar mac[6];
296         Etherrock *er = ifc->arg;
297
298         /* get mac address of destination */
299         a = arpget(er->f->arp, bp, version, ifc, ip, mac);
300         if(a){
301                 /* check for broadcast or multicast */
302                 bp = multicastarp(er->f, a, ifc->m, mac);
303                 if(bp==nil){
304                         switch(version){
305                         case V4:
306                                 sendarp(ifc, a);
307                                 break;
308                         case V6: 
309                                 resolveaddr6(ifc, a);
310                                 break;
311                         default:
312                                 panic("etherbwrite: version %d", version);
313                         }
314                         return;
315                 }
316         }
317
318         /* make it a single block with space for the ether header */
319         bp = padblock(bp, ifc->m->hsize);
320         if(bp->next)
321                 bp = concatblock(bp);
322         if(BLEN(bp) < ifc->mintu)
323                 bp = adjustblock(bp, ifc->mintu);
324         eh = (Etherhdr*)bp->rp;
325
326         /* copy in mac addresses and ether type */
327         memmove(eh->s, ifc->mac, sizeof(eh->s));
328         memmove(eh->d, mac, sizeof(eh->d));
329
330         switch(version){
331         case V4:
332                 eh->t[0] = 0x08;
333                 eh->t[1] = 0x00;
334                 devtab[er->mchan4->type]->bwrite(er->mchan4, bp, 0);
335                 break;
336         case V6:
337                 eh->t[0] = 0x86;
338                 eh->t[1] = 0xDD;
339                 devtab[er->mchan6->type]->bwrite(er->mchan6, bp, 0);
340                 break;
341         default:
342                 panic("etherbwrite2: version %d", version);
343         }
344         ifc->out++;
345 }
346
347
348 /*
349  *  process to read from the ethernet
350  */
351 static void
352 etherread4(void *a)
353 {
354         Ipifc *ifc;
355         Block *bp;
356         Etherrock *er;
357
358         ifc = a;
359         er = ifc->arg;
360         er->read4p = up;        /* hide identity under a rock for unbind */
361         if(waserror()){
362                 er->read4p = 0;
363                 pexit("hangup", 1);
364         }
365         for(;;){
366                 bp = devtab[er->mchan4->type]->bread(er->mchan4, ifc->maxtu, 0);
367                 if(!canrlock(ifc)){
368                         freeb(bp);
369                         continue;
370                 }
371                 if(waserror()){
372                         runlock(ifc);
373                         nexterror();
374                 }
375                 ifc->in++;
376                 bp->rp += ifc->m->hsize;
377                 if(ifc->lifc == nil)
378                         freeb(bp);
379                 else
380                         ipiput4(er->f, ifc, bp);
381                 runlock(ifc);
382                 poperror();
383         }
384 }
385
386
387 /*
388  *  process to read from the ethernet, IPv6
389  */
390 static void
391 etherread6(void *a)
392 {
393         Ipifc *ifc;
394         Block *bp;
395         Etherrock *er;
396
397         ifc = a;
398         er = ifc->arg;
399         er->read6p = up;        /* hide identity under a rock for unbind */
400         if(waserror()){
401                 er->read6p = 0;
402                 pexit("hangup", 1);
403         }
404         for(;;){
405                 bp = devtab[er->mchan6->type]->bread(er->mchan6, ifc->maxtu, 0);
406                 if(!canrlock(ifc)){
407                         freeb(bp);
408                         continue;
409                 }
410                 if(waserror()){
411                         runlock(ifc);
412                         nexterror();
413                 }
414                 ifc->in++;
415                 bp->rp += ifc->m->hsize;
416                 if(ifc->lifc == nil)
417                         freeb(bp);
418                 else
419                         ipiput6(er->f, ifc, bp);
420                 runlock(ifc);
421                 poperror();
422         }
423 }
424
425 static void
426 etheraddmulti(Ipifc *ifc, uchar *a, uchar *)
427 {
428         uchar mac[6];
429         char buf[64];
430         Etherrock *er = ifc->arg;
431         int version;
432
433         version = multicastea(mac, a);
434         sprint(buf, "addmulti %E", mac);
435         switch(version){
436         case V4:
437                 devtab[er->cchan4->type]->write(er->cchan4, buf, strlen(buf), 0);
438                 break;
439         case V6:
440                 devtab[er->cchan6->type]->write(er->cchan6, buf, strlen(buf), 0);
441                 break;
442         default:
443                 panic("etheraddmulti: version %d", version);
444         }
445 }
446
447 static void
448 etherremmulti(Ipifc *ifc, uchar *a, uchar *)
449 {
450         uchar mac[6];
451         char buf[64];
452         Etherrock *er = ifc->arg;
453         int version;
454
455         version = multicastea(mac, a);
456         sprint(buf, "remmulti %E", mac);
457         switch(version){
458         case V4:
459                 devtab[er->cchan4->type]->write(er->cchan4, buf, strlen(buf), 0);
460                 break;
461         case V6:
462                 devtab[er->cchan6->type]->write(er->cchan6, buf, strlen(buf), 0);
463                 break;
464         default:
465                 panic("etherremmulti: version %d", version);
466         }
467 }
468
469 /*
470  *  send an ethernet arp
471  *  (only v4, v6 uses the neighbor discovery, rfc1970)
472  */
473 static void
474 sendarp(Ipifc *ifc, Arpent *a)
475 {
476         int n;
477         Block *bp;
478         Etherarp *e;
479         Etherrock *er = ifc->arg;
480
481         /* don't do anything if it's been less than a second since the last */
482         if(NOW - a->ctime < 1000){
483                 arprelease(er->f->arp, a);
484                 return;
485         }
486
487         /* remove all but the last message */
488         while((bp = a->hold) != nil){
489                 if(bp == a->last)
490                         break;
491                 a->hold = bp->list;
492                 freeblist(bp);
493         }
494
495         /* try to keep it around for a second more */
496         a->ctime = NOW;
497         arprelease(er->f->arp, a);
498
499         n = sizeof(Etherarp);
500         if(n < a->type->mintu)
501                 n = a->type->mintu;
502         bp = allocb(n);
503         memset(bp->rp, 0, n);
504         e = (Etherarp*)bp->rp;
505         memmove(e->tpa, a->ip+IPv4off, sizeof(e->tpa));
506         ipv4local(ifc, e->spa);
507         memmove(e->sha, ifc->mac, sizeof(e->sha));
508         memset(e->d, 0xff, sizeof(e->d));               /* ethernet broadcast */
509         memmove(e->s, ifc->mac, sizeof(e->s));
510
511         hnputs(e->type, ETARP);
512         hnputs(e->hrd, 1);
513         hnputs(e->pro, ETIP4);
514         e->hln = sizeof(e->sha);
515         e->pln = sizeof(e->spa);
516         hnputs(e->op, ARPREQUEST);
517         bp->wp += n;
518
519         n = devtab[er->achan->type]->bwrite(er->achan, bp, 0);
520         if(n < 0)
521                 print("arp: send: %r\n");
522 }
523
524 static void
525 resolveaddr6(Ipifc *ifc, Arpent *a)
526 {
527         int sflag;
528         Block *bp;
529         Etherrock *er = ifc->arg;
530         uchar ipsrc[IPaddrlen];
531
532         /* don't do anything if it's been less than a second since the last */
533         if(NOW - a->ctime < ReTransTimer){
534                 arprelease(er->f->arp, a);
535                 return;
536         }
537
538         /* remove all but the last message */
539         while((bp = a->hold) != nil){
540                 if(bp == a->last)
541                         break;
542                 a->hold = bp->list;
543                 freeblist(bp);
544         }
545
546         /* try to keep it around for a second more */
547         a->ctime = NOW;
548         a->rtime = NOW + ReTransTimer;
549         if(a->rxtsrem <= 0) {
550                 arprelease(er->f->arp, a);
551                 return;
552         }
553
554         a->rxtsrem--;
555         arprelease(er->f->arp, a);
556
557         if(sflag = ipv6anylocal(ifc, ipsrc)) 
558                 icmpns(er->f, ipsrc, sflag, a->ip, TARG_MULTI, ifc->mac);
559 }
560
561 /*
562  *  send a gratuitous arp to refresh arp caches
563  */
564 static void
565 sendgarp(Ipifc *ifc, uchar *ip)
566 {
567         int n;
568         Block *bp;
569         Etherarp *e;
570         Etherrock *er = ifc->arg;
571
572         /* don't arp for our initial non address */
573         if(ipcmp(ip, IPnoaddr) == 0)
574                 return;
575
576         n = sizeof(Etherarp);
577         if(n < ifc->m->mintu)
578                 n = ifc->m->mintu;
579         bp = allocb(n);
580         memset(bp->rp, 0, n);
581         e = (Etherarp*)bp->rp;
582         memmove(e->tpa, ip+IPv4off, sizeof(e->tpa));
583         memmove(e->spa, ip+IPv4off, sizeof(e->spa));
584         memmove(e->sha, ifc->mac, sizeof(e->sha));
585         memset(e->d, 0xff, sizeof(e->d));               /* ethernet broadcast */
586         memmove(e->s, ifc->mac, sizeof(e->s));
587
588         hnputs(e->type, ETARP);
589         hnputs(e->hrd, 1);
590         hnputs(e->pro, ETIP4);
591         e->hln = sizeof(e->sha);
592         e->pln = sizeof(e->spa);
593         hnputs(e->op, ARPREQUEST);
594         bp->wp += n;
595
596         n = devtab[er->achan->type]->bwrite(er->achan, bp, 0);
597         if(n < 0)
598                 print("garp: send: %r\n");
599 }
600
601 static void
602 recvarp(Ipifc *ifc)
603 {
604         int n;
605         Block *ebp, *rbp;
606         Etherarp *e, *r;
607         uchar ip[IPaddrlen];
608         static uchar eprinted[4];
609         Etherrock *er = ifc->arg;
610
611         ebp = devtab[er->achan->type]->bread(er->achan, ifc->maxtu, 0);
612         if(ebp == nil) {
613                 print("arp: rcv: %r\n");
614                 return;
615         }
616
617         e = (Etherarp*)ebp->rp;
618         switch(nhgets(e->op)) {
619         default:
620                 break;
621
622         case ARPREPLY:
623                 /* check for machine using my ip address */
624                 v4tov6(ip, e->spa);
625                 if(iplocalonifc(ifc, ip) || ipproxyifc(er->f, ifc, ip)){
626                         if(memcmp(e->sha, ifc->mac, sizeof(e->sha)) != 0){
627                                 print("arprep: 0x%E/0x%E also has ip addr %V\n",
628                                         e->s, e->sha, e->spa);
629                                 break;
630                         }
631                 }
632
633                 /* make sure we're not entering broadcast addresses */
634                 if(ipcmp(ip, ipbroadcast) == 0 ||
635                         !memcmp(e->sha, etherbroadcast, sizeof(e->sha))){
636                         print("arprep: 0x%E/0x%E cannot register broadcast address %I\n",
637                                 e->s, e->sha, e->spa);
638                         break;
639                 }
640
641                 arpenter(er->f, V4, e->spa, e->sha, sizeof(e->sha), 0);
642                 break;
643
644         case ARPREQUEST:
645                 /* don't answer arps till we know who we are */
646                 if(ifc->lifc == 0)
647                         break;
648
649                 /* check for machine using my ip or ether address */
650                 v4tov6(ip, e->spa);
651                 if(iplocalonifc(ifc, ip) || ipproxyifc(er->f, ifc, ip)){
652                         if(memcmp(e->sha, ifc->mac, sizeof(e->sha)) != 0){
653                                 if (memcmp(eprinted, e->spa, sizeof(e->spa))){
654                                         /* print only once */
655                                         print("arpreq: 0x%E also has ip addr %V\n", e->sha, e->spa);
656                                         memmove(eprinted, e->spa, sizeof(e->spa));
657                                 }
658                         }
659                 } else {
660                         if(memcmp(e->sha, ifc->mac, sizeof(e->sha)) == 0){
661                                 print("arpreq: %V also has ether addr %E\n", e->spa, e->sha);
662                                 break;
663                         }
664                 }
665
666                 /* refresh what we know about sender */
667                 arpenter(er->f, V4, e->spa, e->sha, sizeof(e->sha), 1);
668
669                 /* answer only requests for our address or systems we're proxying for */
670                 v4tov6(ip, e->tpa);
671                 if(!iplocalonifc(ifc, ip))
672                 if(!ipproxyifc(er->f, ifc, ip))
673                         break;
674
675                 n = sizeof(Etherarp);
676                 if(n < ifc->mintu)
677                         n = ifc->mintu;
678                 rbp = allocb(n);
679                 r = (Etherarp*)rbp->rp;
680                 memset(r, 0, sizeof(Etherarp));
681                 hnputs(r->type, ETARP);
682                 hnputs(r->hrd, 1);
683                 hnputs(r->pro, ETIP4);
684                 r->hln = sizeof(r->sha);
685                 r->pln = sizeof(r->spa);
686                 hnputs(r->op, ARPREPLY);
687                 memmove(r->tha, e->sha, sizeof(r->tha));
688                 memmove(r->tpa, e->spa, sizeof(r->tpa));
689                 memmove(r->sha, ifc->mac, sizeof(r->sha));
690                 memmove(r->spa, e->tpa, sizeof(r->spa));
691                 memmove(r->d, e->sha, sizeof(r->d));
692                 memmove(r->s, ifc->mac, sizeof(r->s));
693                 rbp->wp += n;
694
695                 n = devtab[er->achan->type]->bwrite(er->achan, rbp, 0);
696                 if(n < 0)
697                         print("arp: write: %r\n");
698         }
699         freeb(ebp);
700 }
701
702 static void
703 recvarpproc(void *v)
704 {
705         Ipifc *ifc = v;
706         Etherrock *er = ifc->arg;
707
708         er->arpp = up;
709         if(waserror()){
710                 er->arpp = 0;
711                 pexit("hangup", 1);
712         }
713         for(;;)
714                 recvarp(ifc);
715 }
716
717 static int
718 multicastea(uchar *ea, uchar *ip)
719 {
720         int x;
721
722         switch(x = ipismulticast(ip)){
723         case V4:
724                 ea[0] = 0x01;
725                 ea[1] = 0x00;
726                 ea[2] = 0x5e;
727                 ea[3] = ip[13] & 0x7f;
728                 ea[4] = ip[14];
729                 ea[5] = ip[15];
730                 break;
731         case V6:
732                 ea[0] = 0x33;
733                 ea[1] = 0x33;
734                 ea[2] = ip[12];
735                 ea[3] = ip[13];
736                 ea[4] = ip[14];
737                 ea[5] = ip[15];
738                 break;
739         }
740         return x;
741 }
742
743 /*
744  *  fill in an arp entry for broadcast or multicast
745  *  addresses.  Return the first queued packet for the
746  *  IP address.
747  */
748 static Block*
749 multicastarp(Fs *f, Arpent *a, Medium *medium, uchar *mac)
750 {
751         /* is it broadcast? */
752         switch(ipforme(f, a->ip)){
753         case Runi:
754                 return nil;
755         case Rbcast:
756                 memset(mac, 0xff, 6);
757                 return arpresolve(f->arp, a, medium, mac);
758         default:
759                 break;
760         }
761
762         /* if multicast, fill in mac */
763         switch(multicastea(mac, a->ip)){
764         case V4:
765         case V6:
766                 return arpresolve(f->arp, a, medium, mac);
767         }
768
769         /* let arp take care of it */
770         return nil;
771 }
772
773 void
774 ethermediumlink(void)
775 {
776         addipmedium(&ethermedium);
777         addipmedium(&gbemedium);
778 }
779
780
781 static void 
782 etherpref2addr(uchar *pref, uchar *ea)
783 {
784         pref[8]  = ea[0] | 0x2;
785         pref[9]  = ea[1];
786         pref[10] = ea[2];
787         pref[11] = 0xFF;
788         pref[12] = 0xFE;
789         pref[13] = ea[3];
790         pref[14] = ea[4];
791         pref[15] = ea[5];
792 }