xref: /linux/drivers/net/arcnet/rfc1201.c (revision 79790b6818e96c58fe2bffee1b418c16e64e7b80)
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 
38 MODULE_DESCRIPTION("ARCNet packet format (RFC 1201) module");
39 MODULE_LICENSE("GPL");
40 
41 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
42 static void rx(struct net_device *dev, int bufnum,
43 	       struct archdr *pkthdr, int length);
44 static int build_header(struct sk_buff *skb, struct net_device *dev,
45 			unsigned short type, uint8_t daddr);
46 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
47 		      int bufnum);
48 static int continue_tx(struct net_device *dev, int bufnum);
49 
50 static 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 
arcnet_rfc1201_init(void)61 static 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 
arcnet_rfc1201_exit(void)80 static void __exit arcnet_rfc1201_exit(void)
81 {
82 	arcnet_unregister_proto(&rfc1201_proto);
83 }
84 
85 module_init(arcnet_rfc1201_init);
86 module_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  */
type_trans(struct sk_buff * skb,struct net_device * dev)92 static __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, 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 */
rx(struct net_device * dev,int bufnum,struct archdr * pkthdr,int length)133 static 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(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(length + ARC_HDR_SIZE, GFP_ATOMIC);
183 		if (!skb) {
184 			dev->stats.rx_dropped++;
185 			return;
186 		}
187 		skb_put(skb, 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, "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(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(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(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(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, 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, "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. */
build_header(struct sk_buff * skb,struct net_device * dev,unsigned short type,uint8_t daddr)378 static 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, 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 
load_pkt(struct net_device * dev,struct arc_hardware * hard,struct arc_rfc1201 * soft,int softlen,int bufnum)443 static 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 
prepare_tx(struct net_device * dev,struct archdr * pkt,int length,int bufnum)476 static 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, &pkt->hard, &pkt->soft.rfc1201, length, bufnum);
507 
508 	return 1;		/* done */
509 }
510 
continue_tx(struct net_device * dev,int bufnum)511 static 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, newsoft, 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