1/*
2 * Linux ARCnet driver - RFC1201 (standard) packet encapsulation
3 *
4 * Written 1994-1999 by Avery Pennarun.
5 * Derived from skeleton.c by Donald Becker.
6 *
7 * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
8 * for sponsoring the further development of this driver.
9 *
10 * **********************
11 *
12 * The original copyright of skeleton.c was as follows:
13 *
14 * skeleton.c Written 1993 by Donald Becker.
15 * Copyright 1993 United States Government as represented by the
16 * Director, National Security Agency. This software may only be used
17 * and distributed according to the terms of the GNU General Public License as
18 * modified by SRC, incorporated herein by reference.
19 *
20 * **********************
21 *
22 * For more details, see drivers/net/arcnet.c
23 *
24 * **********************
25 */
26
27#define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
28
29#include <linux/gfp.h>
30#include <linux/module.h>
31#include <linux/init.h>
32#include <linux/if_arp.h>
33#include <linux/netdevice.h>
34#include <linux/skbuff.h>
35
36#include "arcdevice.h"
37
38MODULE_DESCRIPTION("ARCNet packet format (RFC 1201) module");
39MODULE_LICENSE("GPL");
40
41static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
42static void rx(struct net_device *dev, int bufnum,
43 struct archdr *pkthdr, int length);
44static int build_header(struct sk_buff *skb, struct net_device *dev,
45 unsigned short type, uint8_t daddr);
46static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
47 int bufnum);
48static int continue_tx(struct net_device *dev, int bufnum);
49
50static struct ArcProto rfc1201_proto = {
51 .suffix = 'a',
52 .mtu = 1500, /* could be more, but some receivers can't handle it... */
53 .is_ip = 1, /* This is for sending IP and ARP packages */
54 .rx = rx,
55 .build_header = build_header,
56 .prepare_tx = prepare_tx,
57 .continue_tx = continue_tx,
58 .ack_tx = NULL
59};
60
61static int __init arcnet_rfc1201_init(void)
62{
63 pr_info("%s\n", "RFC1201 \"standard\" (`a') encapsulation support loaded");
64
65 arc_proto_map[ARC_P_IP]
66 = arc_proto_map[ARC_P_IPV6]
67 = arc_proto_map[ARC_P_ARP]
68 = arc_proto_map[ARC_P_RARP]
69 = arc_proto_map[ARC_P_IPX]
70 = arc_proto_map[ARC_P_NOVELL_EC]
71 = &rfc1201_proto;
72
73 /* if someone else already owns the broadcast, we won't take it */
74 if (arc_bcast_proto == arc_proto_default)
75 arc_bcast_proto = &rfc1201_proto;
76
77 return 0;
78}
79
80static void __exit arcnet_rfc1201_exit(void)
81{
82 arcnet_unregister_proto(proto: &rfc1201_proto);
83}
84
85module_init(arcnet_rfc1201_init);
86module_exit(arcnet_rfc1201_exit);
87
88/* Determine a packet's protocol ID.
89 *
90 * With ARCnet we have to convert everything to Ethernet-style stuff.
91 */
92static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
93{
94 struct archdr *pkt = (struct archdr *)skb->data;
95 struct arc_rfc1201 *soft = &pkt->soft.rfc1201;
96 int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;
97
98 /* Pull off the arcnet header. */
99 skb_reset_mac_header(skb);
100 skb_pull(skb, len: hdr_size);
101
102 if (pkt->hard.dest == 0) {
103 skb->pkt_type = PACKET_BROADCAST;
104 } else if (dev->flags & IFF_PROMISC) {
105 /* if we're not sending to ourselves :) */
106 if (pkt->hard.dest != dev->dev_addr[0])
107 skb->pkt_type = PACKET_OTHERHOST;
108 }
109 /* now return the protocol number */
110 switch (soft->proto) {
111 case ARC_P_IP:
112 return htons(ETH_P_IP);
113 case ARC_P_IPV6:
114 return htons(ETH_P_IPV6);
115 case ARC_P_ARP:
116 return htons(ETH_P_ARP);
117 case ARC_P_RARP:
118 return htons(ETH_P_RARP);
119
120 case ARC_P_IPX:
121 case ARC_P_NOVELL_EC:
122 return htons(ETH_P_802_3);
123 default:
124 dev->stats.rx_errors++;
125 dev->stats.rx_crc_errors++;
126 return 0;
127 }
128
129 return htons(ETH_P_IP);
130}
131
132/* packet receiver */
133static void rx(struct net_device *dev, int bufnum,
134 struct archdr *pkthdr, int length)
135{
136 struct arcnet_local *lp = netdev_priv(dev);
137 struct sk_buff *skb;
138 struct archdr *pkt = pkthdr;
139 struct arc_rfc1201 *soft = &pkthdr->soft.rfc1201;
140 int saddr = pkt->hard.source, ofs;
141 struct Incoming *in = &lp->rfc1201.incoming[saddr];
142
143 arc_printk(D_DURING, dev, "it's an RFC1201 packet (length=%d)\n",
144 length);
145
146 if (length >= MinTU)
147 ofs = 512 - length;
148 else
149 ofs = 256 - length;
150
151 if (soft->split_flag == 0xFF) { /* Exception Packet */
152 if (length >= 4 + RFC1201_HDR_SIZE) {
153 arc_printk(D_DURING, dev, "compensating for exception packet\n");
154 } else {
155 arc_printk(D_EXTRA, dev, "short RFC1201 exception packet from %02Xh",
156 saddr);
157 return;
158 }
159
160 /* skip over 4-byte junkola */
161 length -= 4;
162 ofs += 4;
163 lp->hw.copy_from_card(dev, bufnum, 512 - length,
164 soft, sizeof(pkt->soft));
165 }
166 if (!soft->split_flag) { /* not split */
167 arc_printk(D_RX, dev, "incoming is not split (splitflag=%d)\n",
168 soft->split_flag);
169
170 if (in->skb) { /* already assembling one! */
171 arc_printk(D_EXTRA, dev, "aborting assembly (seq=%d) for unsplit packet (splitflag=%d, seq=%d)\n",
172 in->sequence, soft->split_flag,
173 soft->sequence);
174 lp->rfc1201.aborted_seq = soft->sequence;
175 dev_kfree_skb_irq(skb: in->skb);
176 dev->stats.rx_errors++;
177 dev->stats.rx_missed_errors++;
178 in->skb = NULL;
179 }
180 in->sequence = soft->sequence;
181
182 skb = alloc_skb(size: length + ARC_HDR_SIZE, GFP_ATOMIC);
183 if (!skb) {
184 dev->stats.rx_dropped++;
185 return;
186 }
187 skb_put(skb, len: length + ARC_HDR_SIZE);
188 skb->dev = dev;
189
190 pkt = (struct archdr *)skb->data;
191 soft = &pkt->soft.rfc1201;
192
193 /* up to sizeof(pkt->soft) has already
194 * been copied from the card
195 */
196 memcpy(pkt, pkthdr, sizeof(struct archdr));
197 if (length > sizeof(pkt->soft))
198 lp->hw.copy_from_card(dev, bufnum,
199 ofs + sizeof(pkt->soft),
200 pkt->soft.raw + sizeof(pkt->soft),
201 length - sizeof(pkt->soft));
202
203 /* ARP packets have problems when sent from some DOS systems:
204 * the source address is always 0!
205 * So we take the hardware source addr (which is impossible
206 * to fumble) and insert it ourselves.
207 */
208 if (soft->proto == ARC_P_ARP) {
209 struct arphdr *arp = (struct arphdr *)soft->payload;
210
211 /* make sure addresses are the right length */
212 if (arp->ar_hln == 1 && arp->ar_pln == 4) {
213 uint8_t *cptr = (uint8_t *)arp + sizeof(struct arphdr);
214
215 if (!*cptr) { /* is saddr = 00? */
216 arc_printk(D_EXTRA, dev,
217 "ARP source address was 00h, set to %02Xh\n",
218 saddr);
219 dev->stats.rx_crc_errors++;
220 *cptr = saddr;
221 } else {
222 arc_printk(D_DURING, dev, "ARP source address (%Xh) is fine.\n",
223 *cptr);
224 }
225 } else {
226 arc_printk(D_NORMAL, dev, "funny-shaped ARP packet. (%Xh, %Xh)\n",
227 arp->ar_hln, arp->ar_pln);
228 dev->stats.rx_errors++;
229 dev->stats.rx_crc_errors++;
230 }
231 }
232 if (BUGLVL(D_SKB))
233 arcnet_dump_skb(dev, skb, desc: "rx");
234
235 skb->protocol = type_trans(skb, dev);
236 netif_rx(skb);
237 } else { /* split packet */
238 /* NOTE: MSDOS ARP packet correction should only need to
239 * apply to unsplit packets, since ARP packets are so short.
240 *
241 * My interpretation of the RFC1201 document is that if a
242 * packet is received out of order, the entire assembly
243 * process should be aborted.
244 *
245 * The RFC also mentions "it is possible for successfully
246 * received packets to be retransmitted." As of 0.40 all
247 * previously received packets are allowed, not just the
248 * most recent one.
249 *
250 * We allow multiple assembly processes, one for each
251 * ARCnet card possible on the network.
252 * Seems rather like a waste of memory, but there's no
253 * other way to be reliable.
254 */
255
256 arc_printk(D_RX, dev, "packet is split (splitflag=%d, seq=%d)\n",
257 soft->split_flag, in->sequence);
258
259 if (in->skb && in->sequence != soft->sequence) {
260 arc_printk(D_EXTRA, dev, "wrong seq number (saddr=%d, expected=%d, seq=%d, splitflag=%d)\n",
261 saddr, in->sequence, soft->sequence,
262 soft->split_flag);
263 dev_kfree_skb_irq(skb: in->skb);
264 in->skb = NULL;
265 dev->stats.rx_errors++;
266 dev->stats.rx_missed_errors++;
267 in->lastpacket = in->numpackets = 0;
268 }
269 if (soft->split_flag & 1) { /* first packet in split */
270 arc_printk(D_RX, dev, "brand new splitpacket (splitflag=%d)\n",
271 soft->split_flag);
272 if (in->skb) { /* already assembling one! */
273 arc_printk(D_EXTRA, dev, "aborting previous (seq=%d) assembly (splitflag=%d, seq=%d)\n",
274 in->sequence, soft->split_flag,
275 soft->sequence);
276 dev->stats.rx_errors++;
277 dev->stats.rx_missed_errors++;
278 dev_kfree_skb_irq(skb: in->skb);
279 }
280 in->sequence = soft->sequence;
281 in->numpackets = ((unsigned)soft->split_flag >> 1) + 2;
282 in->lastpacket = 1;
283
284 if (in->numpackets > 16) {
285 arc_printk(D_EXTRA, dev, "incoming packet more than 16 segments; dropping. (splitflag=%d)\n",
286 soft->split_flag);
287 lp->rfc1201.aborted_seq = soft->sequence;
288 dev->stats.rx_errors++;
289 dev->stats.rx_length_errors++;
290 return;
291 }
292 in->skb = skb = alloc_skb(size: 508 * in->numpackets + ARC_HDR_SIZE,
293 GFP_ATOMIC);
294 if (!skb) {
295 arc_printk(D_NORMAL, dev, "(split) memory squeeze, dropping packet.\n");
296 lp->rfc1201.aborted_seq = soft->sequence;
297 dev->stats.rx_dropped++;
298 return;
299 }
300 skb->dev = dev;
301 pkt = (struct archdr *)skb->data;
302 soft = &pkt->soft.rfc1201;
303
304 memcpy(pkt, pkthdr, ARC_HDR_SIZE + RFC1201_HDR_SIZE);
305 skb_put(skb, ARC_HDR_SIZE + RFC1201_HDR_SIZE);
306
307 soft->split_flag = 0; /* end result won't be split */
308 } else { /* not first packet */
309 int packetnum = ((unsigned)soft->split_flag >> 1) + 1;
310
311 /* if we're not assembling, there's no point trying to
312 * continue.
313 */
314 if (!in->skb) {
315 if (lp->rfc1201.aborted_seq != soft->sequence) {
316 arc_printk(D_EXTRA, dev, "can't continue split without starting first! (splitflag=%d, seq=%d, aborted=%d)\n",
317 soft->split_flag,
318 soft->sequence,
319 lp->rfc1201.aborted_seq);
320 dev->stats.rx_errors++;
321 dev->stats.rx_missed_errors++;
322 }
323 return;
324 }
325 in->lastpacket++;
326 /* if not the right flag */
327 if (packetnum != in->lastpacket) {
328 /* harmless duplicate? ignore. */
329 if (packetnum <= in->lastpacket - 1) {
330 arc_printk(D_EXTRA, dev, "duplicate splitpacket ignored! (splitflag=%d)\n",
331 soft->split_flag);
332 dev->stats.rx_errors++;
333 dev->stats.rx_frame_errors++;
334 return;
335 }
336 /* "bad" duplicate, kill reassembly */
337 arc_printk(D_EXTRA, dev, "out-of-order splitpacket, reassembly (seq=%d) aborted (splitflag=%d, seq=%d)\n",
338 in->sequence, soft->split_flag,
339 soft->sequence);
340 lp->rfc1201.aborted_seq = soft->sequence;
341 dev_kfree_skb_irq(skb: in->skb);
342 in->skb = NULL;
343 dev->stats.rx_errors++;
344 dev->stats.rx_missed_errors++;
345 in->lastpacket = in->numpackets = 0;
346 return;
347 }
348 pkt = (struct archdr *)in->skb->data;
349 soft = &pkt->soft.rfc1201;
350 }
351
352 skb = in->skb;
353
354 lp->hw.copy_from_card(dev, bufnum, ofs + RFC1201_HDR_SIZE,
355 skb->data + skb->len,
356 length - RFC1201_HDR_SIZE);
357 skb_put(skb, len: length - RFC1201_HDR_SIZE);
358
359 /* are we done? */
360 if (in->lastpacket == in->numpackets) {
361 in->skb = NULL;
362 in->lastpacket = in->numpackets = 0;
363
364 arc_printk(D_SKB_SIZE, dev, "skb: received %d bytes from %02X (unsplit)\n",
365 skb->len, pkt->hard.source);
366 arc_printk(D_SKB_SIZE, dev, "skb: received %d bytes from %02X (split)\n",
367 skb->len, pkt->hard.source);
368 if (BUGLVL(D_SKB))
369 arcnet_dump_skb(dev, skb, desc: "rx");
370
371 skb->protocol = type_trans(skb, dev);
372 netif_rx(skb);
373 }
374 }
375}
376
377/* Create the ARCnet hard/soft headers for RFC1201. */
378static int build_header(struct sk_buff *skb, struct net_device *dev,
379 unsigned short type, uint8_t daddr)
380{
381 struct arcnet_local *lp = netdev_priv(dev);
382 int hdr_size = ARC_HDR_SIZE + RFC1201_HDR_SIZE;
383 struct archdr *pkt = skb_push(skb, len: hdr_size);
384 struct arc_rfc1201 *soft = &pkt->soft.rfc1201;
385
386 /* set the protocol ID according to RFC1201 */
387 switch (type) {
388 case ETH_P_IP:
389 soft->proto = ARC_P_IP;
390 break;
391 case ETH_P_IPV6:
392 soft->proto = ARC_P_IPV6;
393 break;
394 case ETH_P_ARP:
395 soft->proto = ARC_P_ARP;
396 break;
397 case ETH_P_RARP:
398 soft->proto = ARC_P_RARP;
399 break;
400 case ETH_P_IPX:
401 case ETH_P_802_3:
402 case ETH_P_802_2:
403 soft->proto = ARC_P_IPX;
404 break;
405 case ETH_P_ATALK:
406 soft->proto = ARC_P_ATALK;
407 break;
408 default:
409 arc_printk(D_NORMAL, dev, "RFC1201: I don't understand protocol %d (%Xh)\n",
410 type, type);
411 dev->stats.tx_errors++;
412 dev->stats.tx_aborted_errors++;
413 return 0;
414 }
415
416 /* Set the source hardware address.
417 *
418 * This is pretty pointless for most purposes, but it can help in
419 * debugging. ARCnet does not allow us to change the source address
420 * in the actual packet sent.
421 */
422 pkt->hard.source = *dev->dev_addr;
423
424 soft->sequence = htons(lp->rfc1201.sequence++);
425 soft->split_flag = 0; /* split packets are done elsewhere */
426
427 /* see linux/net/ethernet/eth.c to see where I got the following */
428
429 if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
430 /* FIXME: fill in the last byte of the dest ipaddr here
431 * to better comply with RFC1051 in "noarp" mode.
432 * For now, always broadcasting will probably at least get
433 * packets sent out :)
434 */
435 pkt->hard.dest = 0;
436 return hdr_size;
437 }
438 /* otherwise, drop in the dest address */
439 pkt->hard.dest = daddr;
440 return hdr_size;
441}
442
443static void load_pkt(struct net_device *dev, struct arc_hardware *hard,
444 struct arc_rfc1201 *soft, int softlen, int bufnum)
445{
446 struct arcnet_local *lp = netdev_priv(dev);
447 int ofs;
448
449 /* assume length <= XMTU: someone should have handled that by now. */
450
451 if (softlen > MinTU) {
452 hard->offset[0] = 0;
453 hard->offset[1] = ofs = 512 - softlen;
454 } else if (softlen > MTU) { /* exception packet - add an extra header */
455 struct arc_rfc1201 excsoft;
456
457 excsoft.proto = soft->proto;
458 excsoft.split_flag = 0xff;
459 excsoft.sequence = htons(0xffff);
460
461 hard->offset[0] = 0;
462 ofs = 512 - softlen;
463 hard->offset[1] = ofs - RFC1201_HDR_SIZE;
464 lp->hw.copy_to_card(dev, bufnum, ofs - RFC1201_HDR_SIZE,
465 &excsoft, RFC1201_HDR_SIZE);
466 } else {
467 hard->offset[0] = ofs = 256 - softlen;
468 }
469
470 lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
471 lp->hw.copy_to_card(dev, bufnum, ofs, soft, softlen);
472
473 lp->lastload_dest = hard->dest;
474}
475
476static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
477 int bufnum)
478{
479 struct arcnet_local *lp = netdev_priv(dev);
480 const int maxsegsize = XMTU - RFC1201_HDR_SIZE;
481 struct Outgoing *out;
482
483 arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
484 lp->next_tx, lp->cur_tx, bufnum);
485
486 /* hard header is not included in packet length */
487 length -= ARC_HDR_SIZE;
488 pkt->soft.rfc1201.split_flag = 0;
489
490 /* need to do a split packet? */
491 if (length > XMTU) {
492 out = &lp->outgoing;
493
494 out->length = length - RFC1201_HDR_SIZE;
495 out->dataleft = lp->outgoing.length;
496 out->numsegs = (out->dataleft + maxsegsize - 1) / maxsegsize;
497 out->segnum = 0;
498
499 arc_printk(D_DURING, dev, "rfc1201 prep_tx: ready for %d-segment split (%d bytes, seq=%d)\n",
500 out->numsegs, out->length,
501 pkt->soft.rfc1201.sequence);
502
503 return 0; /* not done */
504 }
505 /* just load the packet into the buffers and send it off */
506 load_pkt(dev, hard: &pkt->hard, soft: &pkt->soft.rfc1201, softlen: length, bufnum);
507
508 return 1; /* done */
509}
510
511static int continue_tx(struct net_device *dev, int bufnum)
512{
513 struct arcnet_local *lp = netdev_priv(dev);
514 struct Outgoing *out = &lp->outgoing;
515 struct arc_hardware *hard = &out->pkt->hard;
516 struct arc_rfc1201 *soft = &out->pkt->soft.rfc1201, *newsoft;
517 int maxsegsize = XMTU - RFC1201_HDR_SIZE;
518 int seglen;
519
520 arc_printk(D_DURING, dev,
521 "rfc1201 continue_tx: loading segment %d(+1) of %d (seq=%d)\n",
522 out->segnum, out->numsegs, soft->sequence);
523
524 /* the "new" soft header comes right before the data chunk */
525 newsoft = (struct arc_rfc1201 *)
526 (out->pkt->soft.raw + out->length - out->dataleft);
527
528 if (!out->segnum) /* first packet; newsoft == soft */
529 newsoft->split_flag = ((out->numsegs - 2) << 1) | 1;
530 else {
531 newsoft->split_flag = out->segnum << 1;
532 newsoft->proto = soft->proto;
533 newsoft->sequence = soft->sequence;
534 }
535
536 seglen = maxsegsize;
537 if (seglen > out->dataleft)
538 seglen = out->dataleft;
539 out->dataleft -= seglen;
540
541 load_pkt(dev, hard, soft: newsoft, softlen: seglen + RFC1201_HDR_SIZE, bufnum);
542
543 out->segnum++;
544 if (out->segnum >= out->numsegs)
545 return 1;
546 else
547 return 0;
548}
549

source code of linux/drivers/net/arcnet/rfc1201.c