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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/net/ppp_async.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'drivers/net/ppp_async.c')
-rw-r--r--drivers/net/ppp_async.c1033
1 files changed, 1033 insertions, 0 deletions
diff --git a/drivers/net/ppp_async.c b/drivers/net/ppp_async.c
new file mode 100644
index 000000000000..33b9d79b1aad
--- /dev/null
+++ b/drivers/net/ppp_async.c
@@ -0,0 +1,1033 @@
1/*
2 * PPP async serial channel driver for Linux.
3 *
4 * Copyright 1999 Paul Mackerras.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * This driver provides the encapsulation and framing for sending
12 * and receiving PPP frames over async serial lines. It relies on
13 * the generic PPP layer to give it frames to send and to process
14 * received frames. It implements the PPP line discipline.
15 *
16 * Part of the code in this driver was inspired by the old async-only
17 * PPP driver, written by Michael Callahan and Al Longyear, and
18 * subsequently hacked by Paul Mackerras.
19 */
20
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 <asm/uaccess.h>
34
35#define PPP_VERSION "2.4.2"
36
37#define OBUFSIZE 256
38
39/* Structure for storing local state. */
40struct asyncppp {
41 struct tty_struct *tty;
42 unsigned int flags;
43 unsigned int state;
44 unsigned int rbits;
45 int mru;
46 spinlock_t xmit_lock;
47 spinlock_t recv_lock;
48 unsigned long xmit_flags;
49 u32 xaccm[8];
50 u32 raccm;
51 unsigned int bytes_sent;
52 unsigned int bytes_rcvd;
53
54 struct sk_buff *tpkt;
55 int tpkt_pos;
56 u16 tfcs;
57 unsigned char *optr;
58 unsigned char *olim;
59 unsigned long last_xmit;
60
61 struct sk_buff *rpkt;
62 int lcp_fcs;
63 struct sk_buff_head rqueue;
64
65 struct tasklet_struct tsk;
66
67 atomic_t refcnt;
68 struct semaphore dead_sem;
69 struct ppp_channel chan; /* interface to generic ppp layer */
70 unsigned char obuf[OBUFSIZE];
71};
72
73/* Bit numbers in xmit_flags */
74#define XMIT_WAKEUP 0
75#define XMIT_FULL 1
76#define XMIT_BUSY 2
77
78/* State bits */
79#define SC_TOSS 1
80#define SC_ESCAPE 2
81#define SC_PREV_ERROR 4
82
83/* Bits in rbits */
84#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
85
86static int flag_time = HZ;
87module_param(flag_time, int, 0);
88MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)");
89MODULE_LICENSE("GPL");
90MODULE_ALIAS_LDISC(N_PPP);
91
92/*
93 * Prototypes.
94 */
95static int ppp_async_encode(struct asyncppp *ap);
96static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb);
97static int ppp_async_push(struct asyncppp *ap);
98static void ppp_async_flush_output(struct asyncppp *ap);
99static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
100 char *flags, int count);
101static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd,
102 unsigned long arg);
103static void ppp_async_process(unsigned long arg);
104
105static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
106 int len, int inbound);
107
108static struct ppp_channel_ops async_ops = {
109 ppp_async_send,
110 ppp_async_ioctl
111};
112
113/*
114 * Routines implementing the PPP line discipline.
115 */
116
117/*
118 * We have a potential race on dereferencing tty->disc_data,
119 * because the tty layer provides no locking at all - thus one
120 * cpu could be running ppp_asynctty_receive while another
121 * calls ppp_asynctty_close, which zeroes tty->disc_data and
122 * frees the memory that ppp_asynctty_receive is using. The best
123 * way to fix this is to use a rwlock in the tty struct, but for now
124 * we use a single global rwlock for all ttys in ppp line discipline.
125 *
126 * FIXME: this is no longer true. The _close path for the ldisc is
127 * now guaranteed to be sane.
128 */
129static DEFINE_RWLOCK(disc_data_lock);
130
131static struct asyncppp *ap_get(struct tty_struct *tty)
132{
133 struct asyncppp *ap;
134
135 read_lock(&disc_data_lock);
136 ap = tty->disc_data;
137 if (ap != NULL)
138 atomic_inc(&ap->refcnt);
139 read_unlock(&disc_data_lock);
140 return ap;
141}
142
143static void ap_put(struct asyncppp *ap)
144{
145 if (atomic_dec_and_test(&ap->refcnt))
146 up(&ap->dead_sem);
147}
148
149/*
150 * Called when a tty is put into PPP line discipline. Called in process
151 * context.
152 */
153static int
154ppp_asynctty_open(struct tty_struct *tty)
155{
156 struct asyncppp *ap;
157 int err;
158
159 err = -ENOMEM;
160 ap = kmalloc(sizeof(*ap), GFP_KERNEL);
161 if (ap == 0)
162 goto out;
163
164 /* initialize the asyncppp structure */
165 memset(ap, 0, sizeof(*ap));
166 ap->tty = tty;
167 ap->mru = PPP_MRU;
168 spin_lock_init(&ap->xmit_lock);
169 spin_lock_init(&ap->recv_lock);
170 ap->xaccm[0] = ~0U;
171 ap->xaccm[3] = 0x60000000U;
172 ap->raccm = ~0U;
173 ap->optr = ap->obuf;
174 ap->olim = ap->obuf;
175 ap->lcp_fcs = -1;
176
177 skb_queue_head_init(&ap->rqueue);
178 tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap);
179
180 atomic_set(&ap->refcnt, 1);
181 init_MUTEX_LOCKED(&ap->dead_sem);
182
183 ap->chan.private = ap;
184 ap->chan.ops = &async_ops;
185 ap->chan.mtu = PPP_MRU;
186 err = ppp_register_channel(&ap->chan);
187 if (err)
188 goto out_free;
189
190 tty->disc_data = ap;
191
192 return 0;
193
194 out_free:
195 kfree(ap);
196 out:
197 return err;
198}
199
200/*
201 * Called when the tty is put into another line discipline
202 * or it hangs up. We have to wait for any cpu currently
203 * executing in any of the other ppp_asynctty_* routines to
204 * finish before we can call ppp_unregister_channel and free
205 * the asyncppp struct. This routine must be called from
206 * process context, not interrupt or softirq context.
207 */
208static void
209ppp_asynctty_close(struct tty_struct *tty)
210{
211 struct asyncppp *ap;
212
213 write_lock_irq(&disc_data_lock);
214 ap = tty->disc_data;
215 tty->disc_data = NULL;
216 write_unlock_irq(&disc_data_lock);
217 if (ap == 0)
218 return;
219
220 /*
221 * We have now ensured that nobody can start using ap from now
222 * on, but we have to wait for all existing users to finish.
223 * Note that ppp_unregister_channel ensures that no calls to
224 * our channel ops (i.e. ppp_async_send/ioctl) are in progress
225 * by the time it returns.
226 */
227 if (!atomic_dec_and_test(&ap->refcnt))
228 down(&ap->dead_sem);
229 tasklet_kill(&ap->tsk);
230
231 ppp_unregister_channel(&ap->chan);
232 if (ap->rpkt != 0)
233 kfree_skb(ap->rpkt);
234 skb_queue_purge(&ap->rqueue);
235 if (ap->tpkt != 0)
236 kfree_skb(ap->tpkt);
237 kfree(ap);
238}
239
240/*
241 * Called on tty hangup in process context.
242 *
243 * Wait for I/O to driver to complete and unregister PPP channel.
244 * This is already done by the close routine, so just call that.
245 */
246static int ppp_asynctty_hangup(struct tty_struct *tty)
247{
248 ppp_asynctty_close(tty);
249 return 0;
250}
251
252/*
253 * Read does nothing - no data is ever available this way.
254 * Pppd reads and writes packets via /dev/ppp instead.
255 */
256static ssize_t
257ppp_asynctty_read(struct tty_struct *tty, struct file *file,
258 unsigned char __user *buf, size_t count)
259{
260 return -EAGAIN;
261}
262
263/*
264 * Write on the tty does nothing, the packets all come in
265 * from the ppp generic stuff.
266 */
267static ssize_t
268ppp_asynctty_write(struct tty_struct *tty, struct file *file,
269 const unsigned char *buf, size_t count)
270{
271 return -EAGAIN;
272}
273
274/*
275 * Called in process context only. May be re-entered by multiple
276 * ioctl calling threads.
277 */
278
279static int
280ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file,
281 unsigned int cmd, unsigned long arg)
282{
283 struct asyncppp *ap = ap_get(tty);
284 int err, val;
285 int __user *p = (int __user *)arg;
286
287 if (ap == 0)
288 return -ENXIO;
289 err = -EFAULT;
290 switch (cmd) {
291 case PPPIOCGCHAN:
292 err = -ENXIO;
293 if (ap == 0)
294 break;
295 err = -EFAULT;
296 if (put_user(ppp_channel_index(&ap->chan), p))
297 break;
298 err = 0;
299 break;
300
301 case PPPIOCGUNIT:
302 err = -ENXIO;
303 if (ap == 0)
304 break;
305 err = -EFAULT;
306 if (put_user(ppp_unit_number(&ap->chan), p))
307 break;
308 err = 0;
309 break;
310
311 case TCGETS:
312 case TCGETA:
313 err = n_tty_ioctl(tty, file, cmd, arg);
314 break;
315
316 case TCFLSH:
317 /* flush our buffers and the serial port's buffer */
318 if (arg == TCIOFLUSH || arg == TCOFLUSH)
319 ppp_async_flush_output(ap);
320 err = n_tty_ioctl(tty, file, cmd, arg);
321 break;
322
323 case FIONREAD:
324 val = 0;
325 if (put_user(val, p))
326 break;
327 err = 0;
328 break;
329
330 default:
331 err = -ENOIOCTLCMD;
332 }
333
334 ap_put(ap);
335 return err;
336}
337
338/* No kernel lock - fine */
339static unsigned int
340ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
341{
342 return 0;
343}
344
345static int
346ppp_asynctty_room(struct tty_struct *tty)
347{
348 return 65535;
349}
350
351/*
352 * This can now be called from hard interrupt level as well
353 * as soft interrupt level or mainline.
354 */
355static void
356ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
357 char *cflags, int count)
358{
359 struct asyncppp *ap = ap_get(tty);
360 unsigned long flags;
361
362 if (ap == 0)
363 return;
364 spin_lock_irqsave(&ap->recv_lock, flags);
365 ppp_async_input(ap, buf, cflags, count);
366 spin_unlock_irqrestore(&ap->recv_lock, flags);
367 if (skb_queue_len(&ap->rqueue))
368 tasklet_schedule(&ap->tsk);
369 ap_put(ap);
370 if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
371 && tty->driver->unthrottle)
372 tty->driver->unthrottle(tty);
373}
374
375static void
376ppp_asynctty_wakeup(struct tty_struct *tty)
377{
378 struct asyncppp *ap = ap_get(tty);
379
380 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
381 if (ap == 0)
382 return;
383 set_bit(XMIT_WAKEUP, &ap->xmit_flags);
384 tasklet_schedule(&ap->tsk);
385 ap_put(ap);
386}
387
388
389static struct tty_ldisc ppp_ldisc = {
390 .owner = THIS_MODULE,
391 .magic = TTY_LDISC_MAGIC,
392 .name = "ppp",
393 .open = ppp_asynctty_open,
394 .close = ppp_asynctty_close,
395 .hangup = ppp_asynctty_hangup,
396 .read = ppp_asynctty_read,
397 .write = ppp_asynctty_write,
398 .ioctl = ppp_asynctty_ioctl,
399 .poll = ppp_asynctty_poll,
400 .receive_room = ppp_asynctty_room,
401 .receive_buf = ppp_asynctty_receive,
402 .write_wakeup = ppp_asynctty_wakeup,
403};
404
405static int __init
406ppp_async_init(void)
407{
408 int err;
409
410 err = tty_register_ldisc(N_PPP, &ppp_ldisc);
411 if (err != 0)
412 printk(KERN_ERR "PPP_async: error %d registering line disc.\n",
413 err);
414 return err;
415}
416
417/*
418 * The following routines provide the PPP channel interface.
419 */
420static int
421ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
422{
423 struct asyncppp *ap = chan->private;
424 void __user *argp = (void __user *)arg;
425 int __user *p = argp;
426 int err, val;
427 u32 accm[8];
428
429 err = -EFAULT;
430 switch (cmd) {
431 case PPPIOCGFLAGS:
432 val = ap->flags | ap->rbits;
433 if (put_user(val, p))
434 break;
435 err = 0;
436 break;
437 case PPPIOCSFLAGS:
438 if (get_user(val, p))
439 break;
440 ap->flags = val & ~SC_RCV_BITS;
441 spin_lock_irq(&ap->recv_lock);
442 ap->rbits = val & SC_RCV_BITS;
443 spin_unlock_irq(&ap->recv_lock);
444 err = 0;
445 break;
446
447 case PPPIOCGASYNCMAP:
448 if (put_user(ap->xaccm[0], (u32 __user *)argp))
449 break;
450 err = 0;
451 break;
452 case PPPIOCSASYNCMAP:
453 if (get_user(ap->xaccm[0], (u32 __user *)argp))
454 break;
455 err = 0;
456 break;
457
458 case PPPIOCGRASYNCMAP:
459 if (put_user(ap->raccm, (u32 __user *)argp))
460 break;
461 err = 0;
462 break;
463 case PPPIOCSRASYNCMAP:
464 if (get_user(ap->raccm, (u32 __user *)argp))
465 break;
466 err = 0;
467 break;
468
469 case PPPIOCGXASYNCMAP:
470 if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
471 break;
472 err = 0;
473 break;
474 case PPPIOCSXASYNCMAP:
475 if (copy_from_user(accm, argp, sizeof(accm)))
476 break;
477 accm[2] &= ~0x40000000U; /* can't escape 0x5e */
478 accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */
479 memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
480 err = 0;
481 break;
482
483 case PPPIOCGMRU:
484 if (put_user(ap->mru, p))
485 break;
486 err = 0;
487 break;
488 case PPPIOCSMRU:
489 if (get_user(val, p))
490 break;
491 if (val < PPP_MRU)
492 val = PPP_MRU;
493 ap->mru = val;
494 err = 0;
495 break;
496
497 default:
498 err = -ENOTTY;
499 }
500
501 return err;
502}
503
504/*
505 * This is called at softirq level to deliver received packets
506 * to the ppp_generic code, and to tell the ppp_generic code
507 * if we can accept more output now.
508 */
509static void ppp_async_process(unsigned long arg)
510{
511 struct asyncppp *ap = (struct asyncppp *) arg;
512 struct sk_buff *skb;
513
514 /* process received packets */
515 while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
516 if (skb->cb[0])
517 ppp_input_error(&ap->chan, 0);
518 ppp_input(&ap->chan, skb);
519 }
520
521 /* try to push more stuff out */
522 if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_async_push(ap))
523 ppp_output_wakeup(&ap->chan);
524}
525
526/*
527 * Procedures for encapsulation and framing.
528 */
529
530/*
531 * Procedure to encode the data for async serial transmission.
532 * Does octet stuffing (escaping), puts the address/control bytes
533 * on if A/C compression is disabled, and does protocol compression.
534 * Assumes ap->tpkt != 0 on entry.
535 * Returns 1 if we finished the current frame, 0 otherwise.
536 */
537
538#define PUT_BYTE(ap, buf, c, islcp) do { \
539 if ((islcp && c < 0x20) || (ap->xaccm[c >> 5] & (1 << (c & 0x1f)))) {\
540 *buf++ = PPP_ESCAPE; \
541 *buf++ = c ^ 0x20; \
542 } else \
543 *buf++ = c; \
544} while (0)
545
546static int
547ppp_async_encode(struct asyncppp *ap)
548{
549 int fcs, i, count, c, proto;
550 unsigned char *buf, *buflim;
551 unsigned char *data;
552 int islcp;
553
554 buf = ap->obuf;
555 ap->olim = buf;
556 ap->optr = buf;
557 i = ap->tpkt_pos;
558 data = ap->tpkt->data;
559 count = ap->tpkt->len;
560 fcs = ap->tfcs;
561 proto = (data[0] << 8) + data[1];
562
563 /*
564 * LCP packets with code values between 1 (configure-reqest)
565 * and 7 (code-reject) must be sent as though no options
566 * had been negotiated.
567 */
568 islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
569
570 if (i == 0) {
571 if (islcp)
572 async_lcp_peek(ap, data, count, 0);
573
574 /*
575 * Start of a new packet - insert the leading FLAG
576 * character if necessary.
577 */
578 if (islcp || flag_time == 0
579 || jiffies - ap->last_xmit >= flag_time)
580 *buf++ = PPP_FLAG;
581 ap->last_xmit = jiffies;
582 fcs = PPP_INITFCS;
583
584 /*
585 * Put in the address/control bytes if necessary
586 */
587 if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
588 PUT_BYTE(ap, buf, 0xff, islcp);
589 fcs = PPP_FCS(fcs, 0xff);
590 PUT_BYTE(ap, buf, 0x03, islcp);
591 fcs = PPP_FCS(fcs, 0x03);
592 }
593 }
594
595 /*
596 * Once we put in the last byte, we need to put in the FCS
597 * and closing flag, so make sure there is at least 7 bytes
598 * of free space in the output buffer.
599 */
600 buflim = ap->obuf + OBUFSIZE - 6;
601 while (i < count && buf < buflim) {
602 c = data[i++];
603 if (i == 1 && c == 0 && (ap->flags & SC_COMP_PROT))
604 continue; /* compress protocol field */
605 fcs = PPP_FCS(fcs, c);
606 PUT_BYTE(ap, buf, c, islcp);
607 }
608
609 if (i < count) {
610 /*
611 * Remember where we are up to in this packet.
612 */
613 ap->olim = buf;
614 ap->tpkt_pos = i;
615 ap->tfcs = fcs;
616 return 0;
617 }
618
619 /*
620 * We have finished the packet. Add the FCS and flag.
621 */
622 fcs = ~fcs;
623 c = fcs & 0xff;
624 PUT_BYTE(ap, buf, c, islcp);
625 c = (fcs >> 8) & 0xff;
626 PUT_BYTE(ap, buf, c, islcp);
627 *buf++ = PPP_FLAG;
628 ap->olim = buf;
629
630 kfree_skb(ap->tpkt);
631 ap->tpkt = NULL;
632 return 1;
633}
634
635/*
636 * Transmit-side routines.
637 */
638
639/*
640 * Send a packet to the peer over an async tty line.
641 * Returns 1 iff the packet was accepted.
642 * If the packet was not accepted, we will call ppp_output_wakeup
643 * at some later time.
644 */
645static int
646ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb)
647{
648 struct asyncppp *ap = chan->private;
649
650 ppp_async_push(ap);
651
652 if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
653 return 0; /* already full */
654 ap->tpkt = skb;
655 ap->tpkt_pos = 0;
656
657 ppp_async_push(ap);
658 return 1;
659}
660
661/*
662 * Push as much data as possible out to the tty.
663 */
664static int
665ppp_async_push(struct asyncppp *ap)
666{
667 int avail, sent, done = 0;
668 struct tty_struct *tty = ap->tty;
669 int tty_stuffed = 0;
670
671 /*
672 * We can get called recursively here if the tty write
673 * function calls our wakeup function. This can happen
674 * for example on a pty with both the master and slave
675 * set to PPP line discipline.
676 * We use the XMIT_BUSY bit to detect this and get out,
677 * leaving the XMIT_WAKEUP bit set to tell the other
678 * instance that it may now be able to write more now.
679 */
680 if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
681 return 0;
682 spin_lock_bh(&ap->xmit_lock);
683 for (;;) {
684 if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
685 tty_stuffed = 0;
686 if (!tty_stuffed && ap->optr < ap->olim) {
687 avail = ap->olim - ap->optr;
688 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
689 sent = tty->driver->write(tty, ap->optr, avail);
690 if (sent < 0)
691 goto flush; /* error, e.g. loss of CD */
692 ap->optr += sent;
693 if (sent < avail)
694 tty_stuffed = 1;
695 continue;
696 }
697 if (ap->optr >= ap->olim && ap->tpkt != 0) {
698 if (ppp_async_encode(ap)) {
699 /* finished processing ap->tpkt */
700 clear_bit(XMIT_FULL, &ap->xmit_flags);
701 done = 1;
702 }
703 continue;
704 }
705 /*
706 * We haven't made any progress this time around.
707 * Clear XMIT_BUSY to let other callers in, but
708 * after doing so we have to check if anyone set
709 * XMIT_WAKEUP since we last checked it. If they
710 * did, we should try again to set XMIT_BUSY and go
711 * around again in case XMIT_BUSY was still set when
712 * the other caller tried.
713 */
714 clear_bit(XMIT_BUSY, &ap->xmit_flags);
715 /* any more work to do? if not, exit the loop */
716 if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags)
717 || (!tty_stuffed && ap->tpkt != 0)))
718 break;
719 /* more work to do, see if we can do it now */
720 if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
721 break;
722 }
723 spin_unlock_bh(&ap->xmit_lock);
724 return done;
725
726flush:
727 clear_bit(XMIT_BUSY, &ap->xmit_flags);
728 if (ap->tpkt != 0) {
729 kfree_skb(ap->tpkt);
730 ap->tpkt = NULL;
731 clear_bit(XMIT_FULL, &ap->xmit_flags);
732 done = 1;
733 }
734 ap->optr = ap->olim;
735 spin_unlock_bh(&ap->xmit_lock);
736 return done;
737}
738
739/*
740 * Flush output from our internal buffers.
741 * Called for the TCFLSH ioctl. Can be entered in parallel
742 * but this is covered by the xmit_lock.
743 */
744static void
745ppp_async_flush_output(struct asyncppp *ap)
746{
747 int done = 0;
748
749 spin_lock_bh(&ap->xmit_lock);
750 ap->optr = ap->olim;
751 if (ap->tpkt != NULL) {
752 kfree_skb(ap->tpkt);
753 ap->tpkt = NULL;
754 clear_bit(XMIT_FULL, &ap->xmit_flags);
755 done = 1;
756 }
757 spin_unlock_bh(&ap->xmit_lock);
758 if (done)
759 ppp_output_wakeup(&ap->chan);
760}
761
762/*
763 * Receive-side routines.
764 */
765
766/* see how many ordinary chars there are at the start of buf */
767static inline int
768scan_ordinary(struct asyncppp *ap, const unsigned char *buf, int count)
769{
770 int i, c;
771
772 for (i = 0; i < count; ++i) {
773 c = buf[i];
774 if (c == PPP_ESCAPE || c == PPP_FLAG
775 || (c < 0x20 && (ap->raccm & (1 << c)) != 0))
776 break;
777 }
778 return i;
779}
780
781/* called when a flag is seen - do end-of-packet processing */
782static void
783process_input_packet(struct asyncppp *ap)
784{
785 struct sk_buff *skb;
786 unsigned char *p;
787 unsigned int len, fcs, proto;
788
789 skb = ap->rpkt;
790 if (ap->state & (SC_TOSS | SC_ESCAPE))
791 goto err;
792
793 if (skb == NULL)
794 return; /* 0-length packet */
795
796 /* check the FCS */
797 p = skb->data;
798 len = skb->len;
799 if (len < 3)
800 goto err; /* too short */
801 fcs = PPP_INITFCS;
802 for (; len > 0; --len)
803 fcs = PPP_FCS(fcs, *p++);
804 if (fcs != PPP_GOODFCS)
805 goto err; /* bad FCS */
806 skb_trim(skb, skb->len - 2);
807
808 /* check for address/control and protocol compression */
809 p = skb->data;
810 if (p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
811 /* chop off address/control */
812 if (skb->len < 3)
813 goto err;
814 p = skb_pull(skb, 2);
815 }
816 proto = p[0];
817 if (proto & 1) {
818 /* protocol is compressed */
819 skb_push(skb, 1)[0] = 0;
820 } else {
821 if (skb->len < 2)
822 goto err;
823 proto = (proto << 8) + p[1];
824 if (proto == PPP_LCP)
825 async_lcp_peek(ap, p, skb->len, 1);
826 }
827
828 /* queue the frame to be processed */
829 skb->cb[0] = ap->state;
830 skb_queue_tail(&ap->rqueue, skb);
831 ap->rpkt = NULL;
832 ap->state = 0;
833 return;
834
835 err:
836 /* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */
837 ap->state = SC_PREV_ERROR;
838 if (skb)
839 skb_trim(skb, 0);
840}
841
842/* Called when the tty driver has data for us. Runs parallel with the
843 other ldisc functions but will not be re-entered */
844
845static void
846ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
847 char *flags, int count)
848{
849 struct sk_buff *skb;
850 int c, i, j, n, s, f;
851 unsigned char *sp;
852
853 /* update bits used for 8-bit cleanness detection */
854 if (~ap->rbits & SC_RCV_BITS) {
855 s = 0;
856 for (i = 0; i < count; ++i) {
857 c = buf[i];
858 if (flags != 0 && flags[i] != 0)
859 continue;
860 s |= (c & 0x80)? SC_RCV_B7_1: SC_RCV_B7_0;
861 c = ((c >> 4) ^ c) & 0xf;
862 s |= (0x6996 & (1 << c))? SC_RCV_ODDP: SC_RCV_EVNP;
863 }
864 ap->rbits |= s;
865 }
866
867 while (count > 0) {
868 /* scan through and see how many chars we can do in bulk */
869 if ((ap->state & SC_ESCAPE) && buf[0] == PPP_ESCAPE)
870 n = 1;
871 else
872 n = scan_ordinary(ap, buf, count);
873
874 f = 0;
875 if (flags != 0 && (ap->state & SC_TOSS) == 0) {
876 /* check the flags to see if any char had an error */
877 for (j = 0; j < n; ++j)
878 if ((f = flags[j]) != 0)
879 break;
880 }
881 if (f != 0) {
882 /* start tossing */
883 ap->state |= SC_TOSS;
884
885 } else if (n > 0 && (ap->state & SC_TOSS) == 0) {
886 /* stuff the chars in the skb */
887 skb = ap->rpkt;
888 if (skb == 0) {
889 skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
890 if (skb == 0)
891 goto nomem;
892 /* Try to get the payload 4-byte aligned */
893 if (buf[0] != PPP_ALLSTATIONS)
894 skb_reserve(skb, 2 + (buf[0] & 1));
895 ap->rpkt = skb;
896 }
897 if (n > skb_tailroom(skb)) {
898 /* packet overflowed MRU */
899 ap->state |= SC_TOSS;
900 } else {
901 sp = skb_put(skb, n);
902 memcpy(sp, buf, n);
903 if (ap->state & SC_ESCAPE) {
904 sp[0] ^= 0x20;
905 ap->state &= ~SC_ESCAPE;
906 }
907 }
908 }
909
910 if (n >= count)
911 break;
912
913 c = buf[n];
914 if (flags != NULL && flags[n] != 0) {
915 ap->state |= SC_TOSS;
916 } else if (c == PPP_FLAG) {
917 process_input_packet(ap);
918 } else if (c == PPP_ESCAPE) {
919 ap->state |= SC_ESCAPE;
920 } else if (I_IXON(ap->tty)) {
921 if (c == START_CHAR(ap->tty))
922 start_tty(ap->tty);
923 else if (c == STOP_CHAR(ap->tty))
924 stop_tty(ap->tty);
925 }
926 /* otherwise it's a char in the recv ACCM */
927 ++n;
928
929 buf += n;
930 if (flags != 0)
931 flags += n;
932 count -= n;
933 }
934 return;
935
936 nomem:
937 printk(KERN_ERR "PPPasync: no memory (input pkt)\n");
938 ap->state |= SC_TOSS;
939}
940
941/*
942 * We look at LCP frames going past so that we can notice
943 * and react to the LCP configure-ack from the peer.
944 * In the situation where the peer has been sent a configure-ack
945 * already, LCP is up once it has sent its configure-ack
946 * so the immediately following packet can be sent with the
947 * configured LCP options. This allows us to process the following
948 * packet correctly without pppd needing to respond quickly.
949 *
950 * We only respond to the received configure-ack if we have just
951 * sent a configure-request, and the configure-ack contains the
952 * same data (this is checked using a 16-bit crc of the data).
953 */
954#define CONFREQ 1 /* LCP code field values */
955#define CONFACK 2
956#define LCP_MRU 1 /* LCP option numbers */
957#define LCP_ASYNCMAP 2
958
959static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
960 int len, int inbound)
961{
962 int dlen, fcs, i, code;
963 u32 val;
964
965 data += 2; /* skip protocol bytes */
966 len -= 2;
967 if (len < 4) /* 4 = code, ID, length */
968 return;
969 code = data[0];
970 if (code != CONFACK && code != CONFREQ)
971 return;
972 dlen = (data[2] << 8) + data[3];
973 if (len < dlen)
974 return; /* packet got truncated or length is bogus */
975
976 if (code == (inbound? CONFACK: CONFREQ)) {
977 /*
978 * sent confreq or received confack:
979 * calculate the crc of the data from the ID field on.
980 */
981 fcs = PPP_INITFCS;
982 for (i = 1; i < dlen; ++i)
983 fcs = PPP_FCS(fcs, data[i]);
984
985 if (!inbound) {
986 /* outbound confreq - remember the crc for later */
987 ap->lcp_fcs = fcs;
988 return;
989 }
990
991 /* received confack, check the crc */
992 fcs ^= ap->lcp_fcs;
993 ap->lcp_fcs = -1;
994 if (fcs != 0)
995 return;
996 } else if (inbound)
997 return; /* not interested in received confreq */
998
999 /* process the options in the confack */
1000 data += 4;
1001 dlen -= 4;
1002 /* data[0] is code, data[1] is length */
1003 while (dlen >= 2 && dlen >= data[1] && data[1] >= 2) {
1004 switch (data[0]) {
1005 case LCP_MRU:
1006 val = (data[2] << 8) + data[3];
1007 if (inbound)
1008 ap->mru = val;
1009 else
1010 ap->chan.mtu = val;
1011 break;
1012 case LCP_ASYNCMAP:
1013 val = (data[2] << 24) + (data[3] << 16)
1014 + (data[4] << 8) + data[5];
1015 if (inbound)
1016 ap->raccm = val;
1017 else
1018 ap->xaccm[0] = val;
1019 break;
1020 }
1021 dlen -= data[1];
1022 data += data[1];
1023 }
1024}
1025
1026static void __exit ppp_async_cleanup(void)
1027{
1028 if (tty_register_ldisc(N_PPP, NULL) != 0)
1029 printk(KERN_ERR "failed to unregister PPP line discipline\n");
1030}
1031
1032module_init(ppp_async_init);
1033module_exit(ppp_async_cleanup);
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-12 07:14:54 -0500