summaryrefslogtreecommitdiff
path: root/drivers/net/wan/hdlc_ppp.c
blob: e25b2f058d8c972e2807c744d199c16c41c47fb9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Generic HDLC support routines for Linux
 * Point-to-point protocol support
 *
 * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
 */

#include <linux/errno.h>
#include <linux/hdlc.h>
#include <linux/if_arp.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pkt_sched.h>
#include <linux/poll.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#define DEBUG_CP		0 /* also bytes# to dump */
#define DEBUG_STATE		0
#define DEBUG_HARD_HEADER	0

#define HDLC_ADDR_ALLSTATIONS	0xFF
#define HDLC_CTRL_UI		0x03

#define PID_LCP			0xC021
#define PID_IP			0x0021
#define PID_IPCP		0x8021
#define PID_IPV6		0x0057
#define PID_IPV6CP		0x8057

enum {IDX_LCP = 0, IDX_IPCP, IDX_IPV6CP, IDX_COUNT};
enum {CP_CONF_REQ = 1, CP_CONF_ACK, CP_CONF_NAK, CP_CONF_REJ, CP_TERM_REQ,
      CP_TERM_ACK, CP_CODE_REJ, LCP_PROTO_REJ, LCP_ECHO_REQ, LCP_ECHO_REPLY,
      LCP_DISC_REQ, CP_CODES};
#if DEBUG_CP
static const char *const code_names[CP_CODES] = {
	"0", "ConfReq", "ConfAck", "ConfNak", "ConfRej", "TermReq",
	"TermAck", "CodeRej", "ProtoRej", "EchoReq", "EchoReply", "Discard"
};
static char debug_buffer[64 + 3 * DEBUG_CP];
#endif

enum {LCP_OPTION_MRU = 1, LCP_OPTION_ACCM, LCP_OPTION_MAGIC = 5};

struct hdlc_header {
	u8 address;
	u8 control;
	__be16 protocol;
};

struct cp_header {
	u8 code;
	u8 id;
	__be16 len;
};

struct proto {
	struct net_device *dev;
	struct timer_list timer;
	unsigned long timeout;
	u16 pid;		/* protocol ID */
	u8 state;
	u8 cr_id;		/* ID of last Configuration-Request */
	u8 restart_counter;
};

struct ppp {
	struct proto protos[IDX_COUNT];
	spinlock_t lock;
	unsigned long last_pong;
	unsigned int req_timeout, cr_retries, term_retries;
	unsigned int keepalive_interval, keepalive_timeout;
	u8 seq;			/* local sequence number for requests */
	u8 echo_id;		/* ID of last Echo-Request (LCP) */
};

enum {CLOSED = 0, STOPPED, STOPPING, REQ_SENT, ACK_RECV, ACK_SENT, OPENED,
      STATES, STATE_MASK = 0xF};
enum {START = 0, STOP, TO_GOOD, TO_BAD, RCR_GOOD, RCR_BAD, RCA, RCN, RTR, RTA,
      RUC, RXJ_GOOD, RXJ_BAD, EVENTS};
enum {INV = 0x10, IRC = 0x20, ZRC = 0x40, SCR = 0x80, SCA = 0x100,
      SCN = 0x200, STR = 0x400, STA = 0x800, SCJ = 0x1000};

#if DEBUG_STATE
static const char *const state_names[STATES] = {
	"Closed", "Stopped", "Stopping", "ReqSent", "AckRecv", "AckSent",
	"Opened"
};
static const char *const event_names[EVENTS] = {
	"Start", "Stop", "TO+", "TO-", "RCR+", "RCR-", "RCA", "RCN",
	"RTR", "RTA", "RUC", "RXJ+", "RXJ-"
};
#endif

static struct sk_buff_head tx_queue; /* used when holding the spin lock */

static int ppp_ioctl(struct net_device *dev, struct ifreq *ifr);

static inline struct ppp* get_ppp(struct net_device *dev)
{
	return (struct ppp *)dev_to_hdlc(dev)->state;
}

static inline struct proto* get_proto(struct net_device *dev, u16 pid)
{
	struct ppp *ppp = get_ppp(dev);

	switch (pid) {
	case PID_LCP:
		return &ppp->protos[IDX_LCP];
	case PID_IPCP:
		return &ppp->protos[IDX_IPCP];
	case PID_IPV6CP:
		return &ppp->protos[IDX_IPV6CP];
	default:
		return NULL;
	}
}

static inline const char* proto_name(u16 pid)
{
	switch (pid) {
	case PID_LCP:
		return "LCP";
	case PID_IPCP:
		return "IPCP";
	case PID_IPV6CP:
		return "IPV6CP";
	default:
		return NULL;
	}
}

static __be16 ppp_type_trans(struct sk_buff *skb, struct net_device *dev)
{
	struct hdlc_header *data = (struct hdlc_header*)skb->data;

	if (skb->len < sizeof(struct hdlc_header))
		return htons(ETH_P_HDLC);
	if (data->address != HDLC_ADDR_ALLSTATIONS ||
	    data->control != HDLC_CTRL_UI)
		return htons(ETH_P_HDLC);

	switch (data->protocol) {
	case cpu_to_be16(PID_IP):
		skb_pull(skb, sizeof(struct hdlc_header));
		return htons(ETH_P_IP);

	case cpu_to_be16(PID_IPV6):
		skb_pull(skb, sizeof(struct hdlc_header));
		return htons(ETH_P_IPV6);

	default:
		return htons(ETH_P_HDLC);
	}
}

static int ppp_hard_header(struct sk_buff *skb, struct net_device *dev,
			   u16 type, const void *daddr, const void *saddr,
			   unsigned int len)
{
	struct hdlc_header *data;
#if DEBUG_HARD_HEADER
	printk(KERN_DEBUG "%s: ppp_hard_header() called\n", dev->name);
#endif

	skb_push(skb, sizeof(struct hdlc_header));
	data = (struct hdlc_header*)skb->data;

	data->address = HDLC_ADDR_ALLSTATIONS;
	data->control = HDLC_CTRL_UI;
	switch (type) {
	case ETH_P_IP:
		data->protocol = htons(PID_IP);
		break;
	case ETH_P_IPV6:
		data->protocol = htons(PID_IPV6);
		break;
	case PID_LCP:
	case PID_IPCP:
	case PID_IPV6CP:
		data->protocol = htons(type);
		break;
	default:		/* unknown protocol */
		data->protocol = 0;
	}
	return sizeof(struct hdlc_header);
}

static void ppp_tx_flush(void)
{
	struct sk_buff *skb;
	while ((skb = skb_dequeue(&tx_queue)) != NULL)
		dev_queue_xmit(skb);
}

static void ppp_tx_cp(struct net_device *dev, u16 pid, u8 code,
		      u8 id, unsigned int len, const void *data)
{
	struct sk_buff *skb;
	struct cp_header *cp;
	unsigned int magic_len = 0;
	static u32 magic;

#if DEBUG_CP
	int i;
	char *ptr;
#endif

	if (pid == PID_LCP && (code == LCP_ECHO_REQ || code == LCP_ECHO_REPLY))
		magic_len = sizeof(magic);

	skb = dev_alloc_skb(sizeof(struct hdlc_header) +
			    sizeof(struct cp_header) + magic_len + len);
	if (!skb) {
		netdev_warn(dev, "out of memory in ppp_tx_cp()\n");
		return;
	}
	skb_reserve(skb, sizeof(struct hdlc_header));

	cp = skb_put(skb, sizeof(struct cp_header));
	cp->code = code;
	cp->id = id;
	cp->len = htons(sizeof(struct cp_header) + magic_len + len);

	if (magic_len)
		skb_put_data(skb, &magic, magic_len);
	if (len)
		skb_put_data(skb, data, len);

#if DEBUG_CP
	BUG_ON(code >= CP_CODES);
	ptr = debug_buffer;
	*ptr = '\x0';
	for (i = 0; i < min_t(unsigned int, magic_len + len, DEBUG_CP); i++) {
		sprintf(ptr, " %02X", skb->data[sizeof(struct cp_header) + i]);
		ptr += strlen(ptr);
	}
	printk(KERN_DEBUG "%s: TX %s [%s id 0x%X]%s\n", dev->name,
	       proto_name(pid), code_names[code], id, debug_buffer);
#endif

	ppp_hard_header(skb, dev, pid, NULL, NULL, 0);

	skb->priority = TC_PRIO_CONTROL;
	skb->dev = dev;
	skb->protocol = htons(ETH_P_HDLC);
	skb_reset_network_header(skb);
	skb_queue_tail(&tx_queue, skb);
}

/* State transition table (compare STD-51)
   Events                                   Actions
   TO+  = Timeout with counter > 0          irc = Initialize-Restart-Count
   TO-  = Timeout with counter expired      zrc = Zero-Restart-Count

   RCR+ = Receive-Configure-Request (Good)  scr = Send-Configure-Request
   RCR- = Receive-Configure-Request (Bad)
   RCA  = Receive-Configure-Ack             sca = Send-Configure-Ack
   RCN  = Receive-Configure-Nak/Rej         scn = Send-Configure-Nak/Rej

   RTR  = Receive-Terminate-Request         str = Send-Terminate-Request
   RTA  = Receive-Terminate-Ack             sta = Send-Terminate-Ack

   RUC  = Receive-Unknown-Code              scj = Send-Code-Reject
   RXJ+ = Receive-Code-Reject (permitted)
       or Receive-Protocol-Reject
   RXJ- = Receive-Code-Reject (catastrophic)
       or Receive-Protocol-Reject
*/
static int cp_table[EVENTS][STATES] = {
	/* CLOSED     STOPPED STOPPING REQ_SENT ACK_RECV ACK_SENT OPENED
	     0           1         2       3       4      5          6    */
	{IRC|SCR|3,     INV     , INV ,   INV   , INV ,  INV    ,   INV   }, /* START */
	{   INV   ,      0      ,  0  ,    0    ,  0  ,   0     ,    0    }, /* STOP */
	{   INV   ,     INV     ,STR|2,  SCR|3  ,SCR|3,  SCR|5  ,   INV   }, /* TO+ */
	{   INV   ,     INV     ,  1  ,    1    ,  1  ,    1    ,   INV   }, /* TO- */
	{  STA|0  ,IRC|SCR|SCA|5,  2  ,  SCA|5  ,SCA|6,  SCA|5  ,SCR|SCA|5}, /* RCR+ */
	{  STA|0  ,IRC|SCR|SCN|3,  2  ,  SCN|3  ,SCN|4,  SCN|3  ,SCR|SCN|3}, /* RCR- */
	{  STA|0  ,    STA|1    ,  2  ,  IRC|4  ,SCR|3,    6    , SCR|3   }, /* RCA */
	{  STA|0  ,    STA|1    ,  2  ,IRC|SCR|3,SCR|3,IRC|SCR|5, SCR|3   }, /* RCN */
	{  STA|0  ,    STA|1    ,STA|2,  STA|3  ,STA|3,  STA|3  ,ZRC|STA|2}, /* RTR */
	{    0    ,      1      ,  1  ,    3    ,  3  ,    5    ,  SCR|3  }, /* RTA */
	{  SCJ|0  ,    SCJ|1    ,SCJ|2,  SCJ|3  ,SCJ|4,  SCJ|5  ,  SCJ|6  }, /* RUC */
	{    0    ,      1      ,  2  ,    3    ,  3  ,    5    ,    6    }, /* RXJ+ */
	{    0    ,      1      ,  1  ,    1    ,  1  ,    1    ,IRC|STR|2}, /* RXJ- */
};

/* SCA: RCR+ must supply id, len and data
   SCN: RCR- must supply code, id, len and data
   STA: RTR must supply id
   SCJ: RUC must supply CP packet len and data */
static void ppp_cp_event(struct net_device *dev, u16 pid, u16 event, u8 code,
			 u8 id, unsigned int len, const void *data)
{
	int old_state, action;
	struct ppp *ppp = get_ppp(dev);
	struct proto *proto = get_proto(dev, pid);

	old_state = proto->state;
	BUG_ON(old_state >= STATES);
	BUG_ON(event >= EVENTS);

#if DEBUG_STATE
	printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) %s ...\n", dev->name,
	       proto_name(pid), event_names[event], state_names[proto->state]);
#endif

	action = cp_table[event][old_state];

	proto->state = action & STATE_MASK;
	if (action & (SCR | STR)) /* set Configure-Req/Terminate-Req timer */
		mod_timer(&proto->timer, proto->timeout =
			  jiffies + ppp->req_timeout * HZ);
	if (action & ZRC)
		proto->restart_counter = 0;
	if (action & IRC)
		proto->restart_counter = (proto->state == STOPPING) ?
			ppp->term_retries : ppp->cr_retries;

	if (action & SCR)	/* send Configure-Request */
		ppp_tx_cp(dev, pid, CP_CONF_REQ, proto->cr_id = ++ppp->seq,
			  0, NULL);
	if (action & SCA)	/* send Configure-Ack */
		ppp_tx_cp(dev, pid, CP_CONF_ACK, id, len, data);
	if (action & SCN)	/* send Configure-Nak/Reject */
		ppp_tx_cp(dev, pid, code, id, len, data);
	if (action & STR)	/* send Terminate-Request */
		ppp_tx_cp(dev, pid, CP_TERM_REQ, ++ppp->seq, 0, NULL);
	if (action & STA)	/* send Terminate-Ack */
		ppp_tx_cp(dev, pid, CP_TERM_ACK, id, 0, NULL);
	if (action & SCJ)	/* send Code-Reject */
		ppp_tx_cp(dev, pid, CP_CODE_REJ, ++ppp->seq, len, data);

	if (old_state != OPENED && proto->state == OPENED) {
		netdev_info(dev, "%s up\n", proto_name(pid));
		if (pid == PID_LCP) {
			netif_dormant_off(dev);
			ppp_cp_event(dev, PID_IPCP, START, 0, 0, 0, NULL);
			ppp_cp_event(dev, PID_IPV6CP, START, 0, 0, 0, NULL);
			ppp->last_pong = jiffies;
			mod_timer(&proto->timer, proto->timeout =
				  jiffies + ppp->keepalive_interval * HZ);
		}
	}
	if (old_state == OPENED && proto->state != OPENED) {
		netdev_info(dev, "%s down\n", proto_name(pid));
		if (pid == PID_LCP) {
			netif_dormant_on(dev);
			ppp_cp_event(dev, PID_IPCP, STOP, 0, 0, 0, NULL);
			ppp_cp_event(dev, PID_IPV6CP, STOP, 0, 0, 0, NULL);
		}
	}
	if (old_state != CLOSED && proto->state == CLOSED)
		del_timer(&proto->timer);

#if DEBUG_STATE
	printk(KERN_DEBUG "%s: %s ppp_cp_event(%s) ... %s\n", dev->name,
	       proto_name(pid), event_names[event], state_names[proto->state]);
#endif
}

static void ppp_cp_parse_cr(struct net_device *dev, u16 pid, u8 id,
			    unsigned int req_len, const u8 *data)
{
	static u8 const valid_accm[6] = { LCP_OPTION_ACCM, 6, 0, 0, 0, 0 };
	const u8 *opt;
	u8 *out;
	unsigned int len = req_len, nak_len = 0, rej_len = 0;

	if (!(out = kmalloc(len, GFP_ATOMIC))) {
		dev->stats.rx_dropped++;
		return;	/* out of memory, ignore CR packet */
	}

	for (opt = data; len; len -= opt[1], opt += opt[1]) {
		if (len < 2 || opt[1] < 2 || len < opt[1])
			goto err_out;

		if (pid == PID_LCP)
			switch (opt[0]) {
			case LCP_OPTION_MRU:
				continue; /* MRU always OK and > 1500 bytes? */

			case LCP_OPTION_ACCM: /* async control character map */
				if (opt[1] < sizeof(valid_accm))
					goto err_out;
				if (!memcmp(opt, valid_accm,
					    sizeof(valid_accm)))
					continue;
				if (!rej_len) { /* NAK it */
					memcpy(out + nak_len, valid_accm,
					       sizeof(valid_accm));
					nak_len += sizeof(valid_accm);
					continue;
				}
				break;
			case LCP_OPTION_MAGIC:
				if (len < 6)
					goto err_out;
				if (opt[1] != 6 || (!opt[2] && !opt[3] &&
						    !opt[4] && !opt[5]))
					break; /* reject invalid magic number */
				continue;
			}
		/* reject this option */
		memcpy(out + rej_len, opt, opt[1]);
		rej_len += opt[1];
	}

	if (rej_len)
		ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_REJ, id, rej_len, out);
	else if (nak_len)
		ppp_cp_event(dev, pid, RCR_BAD, CP_CONF_NAK, id, nak_len, out);
	else
		ppp_cp_event(dev, pid, RCR_GOOD, CP_CONF_ACK, id, req_len, data);

	kfree(out);
	return;

err_out:
	dev->stats.rx_errors++;
	kfree(out);
}

static int ppp_rx(struct sk_buff *skb)
{
	struct hdlc_header *hdr = (struct hdlc_header*)skb->data;
	struct net_device *dev = skb->dev;
	struct ppp *ppp = get_ppp(dev);
	struct proto *proto;
	struct cp_header *cp;
	unsigned long flags;
	unsigned int len;
	u16 pid;
#if DEBUG_CP
	int i;
	char *ptr;
#endif

	spin_lock_irqsave(&ppp->lock, flags);
	/* Check HDLC header */
	if (skb->len < sizeof(struct hdlc_header))
		goto rx_error;
	cp = skb_pull(skb, sizeof(struct hdlc_header));
	if (hdr->address != HDLC_ADDR_ALLSTATIONS ||
	    hdr->control != HDLC_CTRL_UI)
		goto rx_error;

	pid = ntohs(hdr->protocol);
	proto = get_proto(dev, pid);
	if (!proto) {
		if (ppp->protos[IDX_LCP].state == OPENED)
			ppp_tx_cp(dev, PID_LCP, LCP_PROTO_REJ,
				  ++ppp->seq, skb->len + 2, &hdr->protocol);
		goto rx_error;
	}

	len = ntohs(cp->len);
	if (len < sizeof(struct cp_header) /* no complete CP header? */ ||
	    skb->len < len /* truncated packet? */)
		goto rx_error;
	skb_pull(skb, sizeof(struct cp_header));
	len -= sizeof(struct cp_header);

	/* HDLC and CP headers stripped from skb */
#if DEBUG_CP
	if (cp->code < CP_CODES)
		sprintf(debug_buffer, "[%s id 0x%X]", code_names[cp->code],
			cp->id);
	else
		sprintf(debug_buffer, "[code %u id 0x%X]", cp->code, cp->id);
	ptr = debug_buffer + strlen(debug_buffer);
	for (i = 0; i < min_t(unsigned int, len, DEBUG_CP); i++) {
		sprintf(ptr, " %02X", skb->data[i]);
		ptr += strlen(ptr);
	}
	printk(KERN_DEBUG "%s: RX %s %s\n", dev->name, proto_name(pid),
	       debug_buffer);
#endif

	/* LCP only */
	if (pid == PID_LCP)
		switch (cp->code) {
		case LCP_PROTO_REJ:
			pid = ntohs(*(__be16*)skb->data);
			if (pid == PID_LCP || pid == PID_IPCP ||
			    pid == PID_IPV6CP)
				ppp_cp_event(dev, pid, RXJ_BAD, 0, 0,
					     0, NULL);
			goto out;

		case LCP_ECHO_REQ: /* send Echo-Reply */
			if (len >= 4 && proto->state == OPENED)
				ppp_tx_cp(dev, PID_LCP, LCP_ECHO_REPLY,
					  cp->id, len - 4, skb->data + 4);
			goto out;

		case LCP_ECHO_REPLY:
			if (cp->id == ppp->echo_id)
				ppp->last_pong = jiffies;
			goto out;

		case LCP_DISC_REQ: /* discard */
			goto out;
		}

	/* LCP, IPCP and IPV6CP */
	switch (cp->code) {
	case CP_CONF_REQ:
		ppp_cp_parse_cr(dev, pid, cp->id, len, skb->data);
		break;

	case CP_CONF_ACK:
		if (cp->id == proto->cr_id)
			ppp_cp_event(dev, pid, RCA, 0, 0, 0, NULL);
		break;

	case CP_CONF_REJ:
	case CP_CONF_NAK:
		if (cp->id == proto->cr_id)
			ppp_cp_event(dev, pid, RCN, 0, 0, 0, NULL);
		break;

	case CP_TERM_REQ:
		ppp_cp_event(dev, pid, RTR, 0, cp->id, 0, NULL);
		break;

	case CP_TERM_ACK:
		ppp_cp_event(dev, pid, RTA, 0, 0, 0, NULL);
		break;

	case CP_CODE_REJ:
		ppp_cp_event(dev, pid, RXJ_BAD, 0, 0, 0, NULL);
		break;

	default:
		len += sizeof(struct cp_header);
		if (len > dev->mtu)
			len = dev->mtu;
		ppp_cp_event(dev, pid, RUC, 0, 0, len, cp);
		break;
	}
	goto out;

rx_error:
	dev->stats.rx_errors++;
out:
	spin_unlock_irqrestore(&ppp->lock, flags);
	dev_kfree_skb_any(skb);
	ppp_tx_flush();
	return NET_RX_DROP;
}

static void ppp_timer(struct timer_list *t)
{
	struct proto *proto = from_timer(proto, t, timer);
	struct ppp *ppp = get_ppp(proto->dev);
	unsigned long flags;

	spin_lock_irqsave(&ppp->lock, flags);
	/* mod_timer could be called after we entered this function but
	 * before we got the lock.
	 */
	if (timer_pending(&proto->timer)) {
		spin_unlock_irqrestore(&ppp->lock, flags);
		return;
	}
	switch (proto->state) {
	case STOPPING:
	case REQ_SENT:
	case ACK_RECV:
	case ACK_SENT:
		if (proto->restart_counter) {
			ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
				     0, NULL);
			proto->restart_counter--;
		} else if (netif_carrier_ok(proto->dev))
			ppp_cp_event(proto->dev, proto->pid, TO_GOOD, 0, 0,
				     0, NULL);
		else
			ppp_cp_event(proto->dev, proto->pid, TO_BAD, 0, 0,
				     0, NULL);
		break;

	case OPENED:
		if (proto->pid != PID_LCP)
			break;
		if (time_after(jiffies, ppp->last_pong +
			       ppp->keepalive_timeout * HZ)) {
			netdev_info(proto->dev, "Link down\n");
			ppp_cp_event(proto->dev, PID_LCP, STOP, 0, 0, 0, NULL);
			ppp_cp_event(proto->dev, PID_LCP, START, 0, 0, 0, NULL);
		} else {	/* send keep-alive packet */
			ppp->echo_id = ++ppp->seq;
			ppp_tx_cp(proto->dev, PID_LCP, LCP_ECHO_REQ,
				  ppp->echo_id, 0, NULL);
			proto->timer.expires = jiffies +
				ppp->keepalive_interval * HZ;
			add_timer(&proto->timer);
		}
		break;
	}
	spin_unlock_irqrestore(&ppp->lock, flags);
	ppp_tx_flush();
}

static void ppp_start(struct net_device *dev)
{
	struct ppp *ppp = get_ppp(dev);
	int i;

	for (i = 0; i < IDX_COUNT; i++) {
		struct proto *proto = &ppp->protos[i];
		proto->dev = dev;
		timer_setup(&proto->timer, ppp_timer, 0);
		proto->state = CLOSED;
	}
	ppp->protos[IDX_LCP].pid = PID_LCP;
	ppp->protos[IDX_IPCP].pid = PID_IPCP;
	ppp->protos[IDX_IPV6CP].pid = PID_IPV6CP;

	ppp_cp_event(dev, PID_LCP, START, 0, 0, 0, NULL);
}

static void ppp_stop(struct net_device *dev)
{
	ppp_cp_event(dev, PID_LCP, STOP, 0, 0, 0, NULL);
}

static void ppp_close(struct net_device *dev)
{
	ppp_tx_flush();
}

static struct hdlc_proto proto = {
	.start		= ppp_start,
	.stop		= ppp_stop,
	.close		= ppp_close,
	.type_trans	= ppp_type_trans,
	.ioctl		= ppp_ioctl,
	.netif_rx	= ppp_rx,
	.module		= THIS_MODULE,
};

static const struct header_ops ppp_header_ops = {
	.create = ppp_hard_header,
};

static int ppp_ioctl(struct net_device *dev, struct ifreq *ifr)
{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	struct ppp *ppp;
	int result;

	switch (ifr->ifr_settings.type) {
	case IF_GET_PROTO:
		if (dev_to_hdlc(dev)->proto != &proto)
			return -EINVAL;
		ifr->ifr_settings.type = IF_PROTO_PPP;
		return 0; /* return protocol only, no settable parameters */

	case IF_PROTO_PPP:
		if (!capable(CAP_NET_ADMIN))
			return -EPERM;

		if (dev->flags & IFF_UP)
			return -EBUSY;

		/* no settable parameters */

		result = hdlc->attach(dev, ENCODING_NRZ,PARITY_CRC16_PR1_CCITT);
		if (result)
			return result;

		result = attach_hdlc_protocol(dev, &proto, sizeof(struct ppp));
		if (result)
			return result;

		ppp = get_ppp(dev);
		spin_lock_init(&ppp->lock);
		ppp->req_timeout = 2;
		ppp->cr_retries = 10;
		ppp->term_retries = 2;
		ppp->keepalive_interval = 10;
		ppp->keepalive_timeout = 60;

		dev->hard_header_len = sizeof(struct hdlc_header);
		dev->header_ops = &ppp_header_ops;
		dev->type = ARPHRD_PPP;
		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
		netif_dormant_on(dev);
		return 0;
	}

	return -EINVAL;
}

static int __init mod_init(void)
{
	skb_queue_head_init(&tx_queue);
	register_hdlc_protocol(&proto);
	return 0;
}

static void __exit mod_exit(void)
{
	unregister_hdlc_protocol(&proto);
}

module_init(mod_init);
module_exit(mod_exit);

MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
MODULE_DESCRIPTION("PPP protocol support for generic HDLC");
MODULE_LICENSE("GPL v2");