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21#include <linux/module.h>
22#include <linux/kernel.h>
23#include <linux/skbuff.h>
24#include <linux/tty.h>
25#include <linux/netdevice.h>
26#include <linux/poll.h>
27#include <linux/crc-ccitt.h>
28#include <linux/ppp_defs.h>
29#include <linux/if_ppp.h>
30#include <linux/ppp_channel.h>
31#include <linux/spinlock.h>
32#include <linux/init.h>
33#include <linux/jiffies.h>
34#include <asm/uaccess.h>
35#include <asm/string.h>
36
37#define PPP_VERSION "2.4.2"
38
39#define OBUFSIZE 256
40
41
42struct asyncppp {
43 struct tty_struct *tty;
44 unsigned int flags;
45 unsigned int state;
46 unsigned int rbits;
47 int mru;
48 spinlock_t xmit_lock;
49 spinlock_t recv_lock;
50 unsigned long xmit_flags;
51 u32 xaccm[8];
52 u32 raccm;
53 unsigned int bytes_sent;
54 unsigned int bytes_rcvd;
55
56 struct sk_buff *tpkt;
57 int tpkt_pos;
58 u16 tfcs;
59 unsigned char *optr;
60 unsigned char *olim;
61 unsigned long last_xmit;
62
63 struct sk_buff *rpkt;
64 int lcp_fcs;
65 struct sk_buff_head rqueue;
66
67 struct tasklet_struct tsk;
68
69 atomic_t refcnt;
70 struct semaphore dead_sem;
71 struct ppp_channel chan;
72 unsigned char obuf[OBUFSIZE];
73};
74
75
76#define XMIT_WAKEUP 0
77#define XMIT_FULL 1
78#define XMIT_BUSY 2
79
80
81#define SC_TOSS 1
82#define SC_ESCAPE 2
83#define SC_PREV_ERROR 4
84
85
86#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
87
88static int flag_time = HZ;
89module_param(flag_time, int, 0);
90MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)");
91MODULE_LICENSE("GPL");
92MODULE_ALIAS_LDISC(N_PPP);
93
94
95
96
97static int ppp_async_encode(struct asyncppp *ap);
98static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb);
99static int ppp_async_push(struct asyncppp *ap);
100static void ppp_async_flush_output(struct asyncppp *ap);
101static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
102 char *flags, int count);
103static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd,
104 unsigned long arg);
105static void ppp_async_process(unsigned long arg);
106
107static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
108 int len, int inbound);
109
110static struct ppp_channel_ops async_ops = {
111 ppp_async_send,
112 ppp_async_ioctl
113};
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131static DEFINE_RWLOCK(disc_data_lock);
132
133static struct asyncppp *ap_get(struct tty_struct *tty)
134{
135 struct asyncppp *ap;
136
137 read_lock(&disc_data_lock);
138 ap = tty->disc_data;
139 if (ap != NULL)
140 atomic_inc(&ap->refcnt);
141 read_unlock(&disc_data_lock);
142 return ap;
143}
144
145static void ap_put(struct asyncppp *ap)
146{
147 if (atomic_dec_and_test(&ap->refcnt))
148 up(&ap->dead_sem);
149}
150
151
152
153
154
155static int
156ppp_asynctty_open(struct tty_struct *tty)
157{
158 struct asyncppp *ap;
159 int err;
160 int speed;
161
162 if (tty->ops->write == NULL)
163 return -EOPNOTSUPP;
164
165 err = -ENOMEM;
166 ap = kzalloc(sizeof(*ap), GFP_KERNEL);
167 if (!ap)
168 goto out;
169
170
171 ap->tty = tty;
172 ap->mru = PPP_MRU;
173 spin_lock_init(&ap->xmit_lock);
174 spin_lock_init(&ap->recv_lock);
175 ap->xaccm[0] = ~0U;
176 ap->xaccm[3] = 0x60000000U;
177 ap->raccm = ~0U;
178 ap->optr = ap->obuf;
179 ap->olim = ap->obuf;
180 ap->lcp_fcs = -1;
181
182 skb_queue_head_init(&ap->rqueue);
183 tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap);
184
185 atomic_set(&ap->refcnt, 1);
186 init_MUTEX_LOCKED(&ap->dead_sem);
187
188 ap->chan.private = ap;
189 ap->chan.ops = &async_ops;
190 ap->chan.mtu = PPP_MRU;
191 speed = tty_get_baud_rate(tty);
192 ap->chan.speed = speed;
193 err = ppp_register_channel(&ap->chan);
194 if (err)
195 goto out_free;
196
197 tty->disc_data = ap;
198 tty->receive_room = 65536;
199 return 0;
200
201 out_free:
202 kfree(ap);
203 out:
204 return err;
205}
206
207
208
209
210
211
212
213
214
215static void
216ppp_asynctty_close(struct tty_struct *tty)
217{
218 struct asyncppp *ap;
219
220 write_lock_irq(&disc_data_lock);
221 ap = tty->disc_data;
222 tty->disc_data = NULL;
223 write_unlock_irq(&disc_data_lock);
224 if (!ap)
225 return;
226
227
228
229
230
231
232
233
234 if (!atomic_dec_and_test(&ap->refcnt))
235 down(&ap->dead_sem);
236 tasklet_kill(&ap->tsk);
237
238 ppp_unregister_channel(&ap->chan);
239 kfree_skb(ap->rpkt);
240 skb_queue_purge(&ap->rqueue);
241 kfree_skb(ap->tpkt);
242 kfree(ap);
243}
244
245
246
247
248
249
250
251static int ppp_asynctty_hangup(struct tty_struct *tty)
252{
253 ppp_asynctty_close(tty);
254 return 0;
255}
256
257
258
259
260
261static ssize_t
262ppp_asynctty_read(struct tty_struct *tty, struct file *file,
263 unsigned char __user *buf, size_t count)
264{
265 return -EAGAIN;
266}
267
268
269
270
271
272static ssize_t
273ppp_asynctty_write(struct tty_struct *tty, struct file *file,
274 const unsigned char *buf, size_t count)
275{
276 return -EAGAIN;
277}
278
279
280
281
282
283
284static int
285ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file,
286 unsigned int cmd, unsigned long arg)
287{
288 struct asyncppp *ap = ap_get(tty);
289 int err, val;
290 int __user *p = (int __user *)arg;
291
292 if (!ap)
293 return -ENXIO;
294 err = -EFAULT;
295 switch (cmd) {
296 case PPPIOCGCHAN:
297 err = -EFAULT;
298 if (put_user(ppp_channel_index(&ap->chan), p))
299 break;
300 err = 0;
301 break;
302
303 case PPPIOCGUNIT:
304 err = -EFAULT;
305 if (put_user(ppp_unit_number(&ap->chan), p))
306 break;
307 err = 0;
308 break;
309
310 case TCFLSH:
311
312 if (arg == TCIOFLUSH || arg == TCOFLUSH)
313 ppp_async_flush_output(ap);
314 err = tty_perform_flush(tty, arg);
315 break;
316
317 case FIONREAD:
318 val = 0;
319 if (put_user(val, p))
320 break;
321 err = 0;
322 break;
323
324 default:
325
326 err = tty_mode_ioctl(tty, file, cmd, arg);
327 }
328
329 ap_put(ap);
330 return err;
331}
332
333
334static unsigned int
335ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
336{
337 return 0;
338}
339
340
341
342
343
344static void
345ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
346 char *cflags, int count)
347{
348 struct asyncppp *ap = ap_get(tty);
349 unsigned long flags;
350
351 if (!ap)
352 return;
353 spin_lock_irqsave(&ap->recv_lock, flags);
354 ppp_async_input(ap, buf, cflags, count);
355 spin_unlock_irqrestore(&ap->recv_lock, flags);
356 if (!skb_queue_empty(&ap->rqueue))
357 tasklet_schedule(&ap->tsk);
358 ap_put(ap);
359 tty_unthrottle(tty);
360}
361
362static void
363ppp_asynctty_wakeup(struct tty_struct *tty)
364{
365 struct asyncppp *ap = ap_get(tty);
366
367 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
368 if (!ap)
369 return;
370 set_bit(XMIT_WAKEUP, &ap->xmit_flags);
371 tasklet_schedule(&ap->tsk);
372 ap_put(ap);
373}
374
375
376static struct tty_ldisc_ops ppp_ldisc = {
377 .owner = THIS_MODULE,
378 .magic = TTY_LDISC_MAGIC,
379 .name = "ppp",
380 .open = ppp_asynctty_open,
381 .close = ppp_asynctty_close,
382 .hangup = ppp_asynctty_hangup,
383 .read = ppp_asynctty_read,
384 .write = ppp_asynctty_write,
385 .ioctl = ppp_asynctty_ioctl,
386 .poll = ppp_asynctty_poll,
387 .receive_buf = ppp_asynctty_receive,
388 .write_wakeup = ppp_asynctty_wakeup,
389};
390
391static int __init
392ppp_async_init(void)
393{
394 int err;
395
396 err = tty_register_ldisc(N_PPP, &ppp_ldisc);
397 if (err != 0)
398 printk(KERN_ERR "PPP_async: error %d registering line disc.\n",
399 err);
400 return err;
401}
402
403
404
405
406static int
407ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
408{
409 struct asyncppp *ap = chan->private;
410 void __user *argp = (void __user *)arg;
411 int __user *p = argp;
412 int err, val;
413 u32 accm[8];
414
415 err = -EFAULT;
416 switch (cmd) {
417 case PPPIOCGFLAGS:
418 val = ap->flags | ap->rbits;
419 if (put_user(val, p))
420 break;
421 err = 0;
422 break;
423 case PPPIOCSFLAGS:
424 if (get_user(val, p))
425 break;
426 ap->flags = val & ~SC_RCV_BITS;
427 spin_lock_irq(&ap->recv_lock);
428 ap->rbits = val & SC_RCV_BITS;
429 spin_unlock_irq(&ap->recv_lock);
430 err = 0;
431 break;
432
433 case PPPIOCGASYNCMAP:
434 if (put_user(ap->xaccm[0], (u32 __user *)argp))
435 break;
436 err = 0;
437 break;
438 case PPPIOCSASYNCMAP:
439 if (get_user(ap->xaccm[0], (u32 __user *)argp))
440 break;
441 err = 0;
442 break;
443
444 case PPPIOCGRASYNCMAP:
445 if (put_user(ap->raccm, (u32 __user *)argp))
446 break;
447 err = 0;
448 break;
449 case PPPIOCSRASYNCMAP:
450 if (get_user(ap->raccm, (u32 __user *)argp))
451 break;
452 err = 0;
453 break;
454
455 case PPPIOCGXASYNCMAP:
456 if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
457 break;
458 err = 0;
459 break;
460 case PPPIOCSXASYNCMAP:
461 if (copy_from_user(accm, argp, sizeof(accm)))
462 break;
463 accm[2] &= ~0x40000000U;
464 accm[3] |= 0x60000000U;
465 memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
466 err = 0;
467 break;
468
469 case PPPIOCGMRU:
470 if (put_user(ap->mru, p))
471 break;
472 err = 0;
473 break;
474 case PPPIOCSMRU:
475 if (get_user(val, p))
476 break;
477 if (val < PPP_MRU)
478 val = PPP_MRU;
479 ap->mru = val;
480 err = 0;
481 break;
482
483 default:
484 err = -ENOTTY;
485 }
486
487 return err;
488}
489
490
491
492
493
494
495static void ppp_async_process(unsigned long arg)
496{
497 struct asyncppp *ap = (struct asyncppp *) arg;
498 struct sk_buff *skb;
499
500
501 while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
502 if (skb->cb[0])
503 ppp_input_error(&ap->chan, 0);
504 ppp_input(&ap->chan, skb);
505 }
506
507
508 if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_async_push(ap))
509 ppp_output_wakeup(&ap->chan);
510}
511
512
513
514
515
516
517
518
519
520
521
522
523
524#define PUT_BYTE(ap, buf, c, islcp) do { \
525 if ((islcp && c < 0x20) || (ap->xaccm[c >> 5] & (1 << (c & 0x1f)))) {\
526 *buf++ = PPP_ESCAPE; \
527 *buf++ = c ^ 0x20; \
528 } else \
529 *buf++ = c; \
530} while (0)
531
532static int
533ppp_async_encode(struct asyncppp *ap)
534{
535 int fcs, i, count, c, proto;
536 unsigned char *buf, *buflim;
537 unsigned char *data;
538 int islcp;
539
540 buf = ap->obuf;
541 ap->olim = buf;
542 ap->optr = buf;
543 i = ap->tpkt_pos;
544 data = ap->tpkt->data;
545 count = ap->tpkt->len;
546 fcs = ap->tfcs;
547 proto = (data[0] << 8) + data[1];
548
549
550
551
552
553
554 islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
555
556 if (i == 0) {
557 if (islcp)
558 async_lcp_peek(ap, data, count, 0);
559
560
561
562
563
564 if (islcp || flag_time == 0
565 || time_after_eq(jiffies, ap->last_xmit + flag_time))
566 *buf++ = PPP_FLAG;
567 ap->last_xmit = jiffies;
568 fcs = PPP_INITFCS;
569
570
571
572
573 if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
574 PUT_BYTE(ap, buf, 0xff, islcp);
575 fcs = PPP_FCS(fcs, 0xff);
576 PUT_BYTE(ap, buf, 0x03, islcp);
577 fcs = PPP_FCS(fcs, 0x03);
578 }
579 }
580
581
582
583
584
585
586 buflim = ap->obuf + OBUFSIZE - 6;
587 while (i < count && buf < buflim) {
588 c = data[i++];
589 if (i == 1 && c == 0 && (ap->flags & SC_COMP_PROT))
590 continue;
591 fcs = PPP_FCS(fcs, c);
592 PUT_BYTE(ap, buf, c, islcp);
593 }
594
595 if (i < count) {
596
597
598
599 ap->olim = buf;
600 ap->tpkt_pos = i;
601 ap->tfcs = fcs;
602 return 0;
603 }
604
605
606
607
608 fcs = ~fcs;
609 c = fcs & 0xff;
610 PUT_BYTE(ap, buf, c, islcp);
611 c = (fcs >> 8) & 0xff;
612 PUT_BYTE(ap, buf, c, islcp);
613 *buf++ = PPP_FLAG;
614 ap->olim = buf;
615
616 kfree_skb(ap->tpkt);
617 ap->tpkt = NULL;
618 return 1;
619}
620
621
622
623
624
625
626
627
628
629
630
631static int
632ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb)
633{
634 struct asyncppp *ap = chan->private;
635
636 ppp_async_push(ap);
637
638 if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
639 return 0;
640 ap->tpkt = skb;
641 ap->tpkt_pos = 0;
642
643 ppp_async_push(ap);
644 return 1;
645}
646
647
648
649
650static int
651ppp_async_push(struct asyncppp *ap)
652{
653 int avail, sent, done = 0;
654 struct tty_struct *tty = ap->tty;
655 int tty_stuffed = 0;
656
657
658
659
660
661
662
663
664
665
666 if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
667 return 0;
668 spin_lock_bh(&ap->xmit_lock);
669 for (;;) {
670 if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
671 tty_stuffed = 0;
672 if (!tty_stuffed && ap->optr < ap->olim) {
673 avail = ap->olim - ap->optr;
674 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
675 sent = tty->ops->write(tty, ap->optr, avail);
676 if (sent < 0)
677 goto flush;
678 ap->optr += sent;
679 if (sent < avail)
680 tty_stuffed = 1;
681 continue;
682 }
683 if (ap->optr >= ap->olim && ap->tpkt) {
684 if (ppp_async_encode(ap)) {
685
686 clear_bit(XMIT_FULL, &ap->xmit_flags);
687 done = 1;
688 }
689 continue;
690 }
691
692
693
694
695
696
697
698
699
700 clear_bit(XMIT_BUSY, &ap->xmit_flags);
701
702 if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags)
703 || (!tty_stuffed && ap->tpkt)))
704 break;
705
706 if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
707 break;
708 }
709 spin_unlock_bh(&ap->xmit_lock);
710 return done;
711
712flush:
713 clear_bit(XMIT_BUSY, &ap->xmit_flags);
714 if (ap->tpkt) {
715 kfree_skb(ap->tpkt);
716 ap->tpkt = NULL;
717 clear_bit(XMIT_FULL, &ap->xmit_flags);
718 done = 1;
719 }
720 ap->optr = ap->olim;
721 spin_unlock_bh(&ap->xmit_lock);
722 return done;
723}
724
725
726
727
728
729
730static void
731ppp_async_flush_output(struct asyncppp *ap)
732{
733 int done = 0;
734
735 spin_lock_bh(&ap->xmit_lock);
736 ap->optr = ap->olim;
737 if (ap->tpkt != NULL) {
738 kfree_skb(ap->tpkt);
739 ap->tpkt = NULL;
740 clear_bit(XMIT_FULL, &ap->xmit_flags);
741 done = 1;
742 }
743 spin_unlock_bh(&ap->xmit_lock);
744 if (done)
745 ppp_output_wakeup(&ap->chan);
746}
747
748
749
750
751
752
753static inline int
754scan_ordinary(struct asyncppp *ap, const unsigned char *buf, int count)
755{
756 int i, c;
757
758 for (i = 0; i < count; ++i) {
759 c = buf[i];
760 if (c == PPP_ESCAPE || c == PPP_FLAG
761 || (c < 0x20 && (ap->raccm & (1 << c)) != 0))
762 break;
763 }
764 return i;
765}
766
767
768static void
769process_input_packet(struct asyncppp *ap)
770{
771 struct sk_buff *skb;
772 unsigned char *p;
773 unsigned int len, fcs, proto;
774
775 skb = ap->rpkt;
776 if (ap->state & (SC_TOSS | SC_ESCAPE))
777 goto err;
778
779 if (skb == NULL)
780 return;
781
782
783 p = skb->data;
784 len = skb->len;
785 if (len < 3)
786 goto err;
787 fcs = PPP_INITFCS;
788 for (; len > 0; --len)
789 fcs = PPP_FCS(fcs, *p++);
790 if (fcs != PPP_GOODFCS)
791 goto err;
792 skb_trim(skb, skb->len - 2);
793
794
795 p = skb->data;
796 if (p[0] == PPP_ALLSTATIONS) {
797
798 if (p[1] != PPP_UI || skb->len < 3)
799 goto err;
800 p = skb_pull(skb, 2);
801 }
802 proto = p[0];
803 if (proto & 1) {
804
805 skb_push(skb, 1)[0] = 0;
806 } else {
807 if (skb->len < 2)
808 goto err;
809 proto = (proto << 8) + p[1];
810 if (proto == PPP_LCP)
811 async_lcp_peek(ap, p, skb->len, 1);
812 }
813
814
815 skb->cb[0] = ap->state;
816 skb_queue_tail(&ap->rqueue, skb);
817 ap->rpkt = NULL;
818 ap->state = 0;
819 return;
820
821 err:
822
823 ap->state = SC_PREV_ERROR;
824 if (skb) {
825
826 skb_trim(skb, 0);
827 skb_reserve(skb, - skb_headroom(skb));
828 }
829}
830
831
832
833
834static void
835ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
836 char *flags, int count)
837{
838 struct sk_buff *skb;
839 int c, i, j, n, s, f;
840 unsigned char *sp;
841
842
843 if (~ap->rbits & SC_RCV_BITS) {
844 s = 0;
845 for (i = 0; i < count; ++i) {
846 c = buf[i];
847 if (flags && flags[i] != 0)
848 continue;
849 s |= (c & 0x80)? SC_RCV_B7_1: SC_RCV_B7_0;
850 c = ((c >> 4) ^ c) & 0xf;
851 s |= (0x6996 & (1 << c))? SC_RCV_ODDP: SC_RCV_EVNP;
852 }
853 ap->rbits |= s;
854 }
855
856 while (count > 0) {
857
858 if ((ap->state & SC_ESCAPE) && buf[0] == PPP_ESCAPE)
859 n = 1;
860 else
861 n = scan_ordinary(ap, buf, count);
862
863 f = 0;
864 if (flags && (ap->state & SC_TOSS) == 0) {
865
866 for (j = 0; j < n; ++j)
867 if ((f = flags[j]) != 0)
868 break;
869 }
870 if (f != 0) {
871
872 ap->state |= SC_TOSS;
873
874 } else if (n > 0 && (ap->state & SC_TOSS) == 0) {
875
876 skb = ap->rpkt;
877 if (!skb) {
878 skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
879 if (!skb)
880 goto nomem;
881 ap->rpkt = skb;
882 }
883 if (skb->len == 0) {
884
885
886
887
888
889
890 if (buf[0] != PPP_ALLSTATIONS)
891 skb_reserve(skb, 2 + (buf[0] & 1));
892 }
893 if (n > skb_tailroom(skb)) {
894
895 ap->state |= SC_TOSS;
896 } else {
897 sp = skb_put(skb, n);
898 memcpy(sp, buf, n);
899 if (ap->state & SC_ESCAPE) {
900 sp[0] ^= 0x20;
901 ap->state &= ~SC_ESCAPE;
902 }
903 }
904 }
905
906 if (n >= count)
907 break;
908
909 c = buf[n];
910 if (flags != NULL && flags[n] != 0) {
911 ap->state |= SC_TOSS;
912 } else if (c == PPP_FLAG) {
913 process_input_packet(ap);
914 } else if (c == PPP_ESCAPE) {
915 ap->state |= SC_ESCAPE;
916 } else if (I_IXON(ap->tty)) {
917 if (c == START_CHAR(ap->tty))
918 start_tty(ap->tty);
919 else if (c == STOP_CHAR(ap->tty))
920 stop_tty(ap->tty);
921 }
922
923 ++n;
924
925 buf += n;
926 if (flags)
927 flags += n;
928 count -= n;
929 }
930 return;
931
932 nomem:
933 printk(KERN_ERR "PPPasync: no memory (input pkt)\n");
934 ap->state |= SC_TOSS;
935}
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950#define CONFREQ 1
951#define CONFACK 2
952#define LCP_MRU 1
953#define LCP_ASYNCMAP 2
954
955static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
956 int len, int inbound)
957{
958 int dlen, fcs, i, code;
959 u32 val;
960
961 data += 2;
962 len -= 2;
963 if (len < 4)
964 return;
965 code = data[0];
966 if (code != CONFACK && code != CONFREQ)
967 return;
968 dlen = (data[2] << 8) + data[3];
969 if (len < dlen)
970 return;
971
972 if (code == (inbound? CONFACK: CONFREQ)) {
973
974
975
976
977 fcs = PPP_INITFCS;
978 for (i = 1; i < dlen; ++i)
979 fcs = PPP_FCS(fcs, data[i]);
980
981 if (!inbound) {
982
983 ap->lcp_fcs = fcs;
984 return;
985 }
986
987
988 fcs ^= ap->lcp_fcs;
989 ap->lcp_fcs = -1;
990 if (fcs != 0)
991 return;
992 } else if (inbound)
993 return;
994
995
996 data += 4;
997 dlen -= 4;
998
999 while (dlen >= 2 && dlen >= data[1] && data[1] >= 2) {
1000 switch (data[0]) {
1001 case LCP_MRU:
1002 val = (data[2] << 8) + data[3];
1003 if (inbound)
1004 ap->mru = val;
1005 else
1006 ap->chan.mtu = val;
1007 break;
1008 case LCP_ASYNCMAP:
1009 val = (data[2] << 24) + (data[3] << 16)
1010 + (data[4] << 8) + data[5];
1011 if (inbound)
1012 ap->raccm = val;
1013 else
1014 ap->xaccm[0] = val;
1015 break;
1016 }
1017 dlen -= data[1];
1018 data += data[1];
1019 }
1020}
1021
1022static void __exit ppp_async_cleanup(void)
1023{
1024 if (tty_unregister_ldisc(N_PPP) != 0)
1025 printk(KERN_ERR "failed to unregister PPP line discipline\n");
1026}
1027
1028module_init(ppp_async_init);
1029module_exit(ppp_async_cleanup);
1030