Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * PPP synchronous tty channel driver for Linux. | |
3 | * | |
4 | * This is a ppp channel driver that can be used with tty device drivers | |
5 | * that are frame oriented, such as synchronous HDLC devices. | |
6 | * | |
7 | * Complete PPP frames without encoding/decoding are exchanged between | |
8 | * the channel driver and the device driver. | |
6aa20a22 | 9 | * |
1da177e4 LT |
10 | * The async map IOCTL codes are implemented to keep the user mode |
11 | * applications happy if they call them. Synchronous PPP does not use | |
12 | * the async maps. | |
13 | * | |
14 | * Copyright 1999 Paul Mackerras. | |
15 | * | |
16 | * Also touched by the grubby hands of Paul Fulghum paulkf@microgate.com | |
17 | * | |
18 | * This program is free software; you can redistribute it and/or | |
19 | * modify it under the terms of the GNU General Public License | |
20 | * as published by the Free Software Foundation; either version | |
21 | * 2 of the License, or (at your option) any later version. | |
22 | * | |
23 | * This driver provides the encapsulation and framing for sending | |
24 | * and receiving PPP frames over sync serial lines. It relies on | |
25 | * the generic PPP layer to give it frames to send and to process | |
26 | * received frames. It implements the PPP line discipline. | |
27 | * | |
28 | * Part of the code in this driver was inspired by the old async-only | |
29 | * PPP driver, written by Michael Callahan and Al Longyear, and | |
30 | * subsequently hacked by Paul Mackerras. | |
31 | * | |
32 | * ==FILEVERSION 20040616== | |
33 | */ | |
34 | ||
35 | #include <linux/module.h> | |
36 | #include <linux/kernel.h> | |
37 | #include <linux/skbuff.h> | |
38 | #include <linux/tty.h> | |
39 | #include <linux/netdevice.h> | |
40 | #include <linux/poll.h> | |
41 | #include <linux/ppp_defs.h> | |
42 | #include <linux/if_ppp.h> | |
43 | #include <linux/ppp_channel.h> | |
44 | #include <linux/spinlock.h> | |
45 | #include <linux/init.h> | |
46 | #include <asm/uaccess.h> | |
47 | #include <asm/semaphore.h> | |
48 | ||
49 | #define PPP_VERSION "2.4.2" | |
50 | ||
51 | /* Structure for storing local state. */ | |
52 | struct syncppp { | |
53 | struct tty_struct *tty; | |
54 | unsigned int flags; | |
55 | unsigned int rbits; | |
56 | int mru; | |
57 | spinlock_t xmit_lock; | |
58 | spinlock_t recv_lock; | |
59 | unsigned long xmit_flags; | |
60 | u32 xaccm[8]; | |
61 | u32 raccm; | |
62 | unsigned int bytes_sent; | |
63 | unsigned int bytes_rcvd; | |
64 | ||
65 | struct sk_buff *tpkt; | |
66 | unsigned long last_xmit; | |
67 | ||
68 | struct sk_buff_head rqueue; | |
69 | ||
70 | struct tasklet_struct tsk; | |
71 | ||
72 | atomic_t refcnt; | |
73 | struct semaphore dead_sem; | |
74 | struct ppp_channel chan; /* interface to generic ppp layer */ | |
75 | }; | |
76 | ||
77 | /* Bit numbers in xmit_flags */ | |
78 | #define XMIT_WAKEUP 0 | |
79 | #define XMIT_FULL 1 | |
80 | ||
81 | /* Bits in rbits */ | |
82 | #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP) | |
83 | ||
84 | #define PPPSYNC_MAX_RQLEN 32 /* arbitrary */ | |
85 | ||
86 | /* | |
87 | * Prototypes. | |
88 | */ | |
89 | static struct sk_buff* ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *); | |
90 | static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb); | |
91 | static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, | |
92 | unsigned long arg); | |
93 | static void ppp_sync_process(unsigned long arg); | |
94 | static int ppp_sync_push(struct syncppp *ap); | |
95 | static void ppp_sync_flush_output(struct syncppp *ap); | |
96 | static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf, | |
97 | char *flags, int count); | |
98 | ||
99 | static struct ppp_channel_ops sync_ops = { | |
100 | ppp_sync_send, | |
101 | ppp_sync_ioctl | |
102 | }; | |
103 | ||
104 | /* | |
105 | * Utility procedures to print a buffer in hex/ascii | |
106 | */ | |
107 | static void | |
108 | ppp_print_hex (register __u8 * out, const __u8 * in, int count) | |
109 | { | |
110 | register __u8 next_ch; | |
f71e1309 | 111 | static const char hex[] = "0123456789ABCDEF"; |
1da177e4 LT |
112 | |
113 | while (count-- > 0) { | |
114 | next_ch = *in++; | |
115 | *out++ = hex[(next_ch >> 4) & 0x0F]; | |
116 | *out++ = hex[next_ch & 0x0F]; | |
117 | ++out; | |
118 | } | |
119 | } | |
120 | ||
121 | static void | |
122 | ppp_print_char (register __u8 * out, const __u8 * in, int count) | |
123 | { | |
124 | register __u8 next_ch; | |
125 | ||
126 | while (count-- > 0) { | |
127 | next_ch = *in++; | |
128 | ||
129 | if (next_ch < 0x20 || next_ch > 0x7e) | |
130 | *out++ = '.'; | |
131 | else { | |
132 | *out++ = next_ch; | |
133 | if (next_ch == '%') /* printk/syslogd has a bug !! */ | |
134 | *out++ = '%'; | |
135 | } | |
136 | } | |
137 | *out = '\0'; | |
138 | } | |
139 | ||
140 | static void | |
141 | ppp_print_buffer (const char *name, const __u8 *buf, int count) | |
142 | { | |
143 | __u8 line[44]; | |
144 | ||
145 | if (name != NULL) | |
146 | printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count); | |
147 | ||
148 | while (count > 8) { | |
149 | memset (line, 32, 44); | |
150 | ppp_print_hex (line, buf, 8); | |
151 | ppp_print_char (&line[8 * 3], buf, 8); | |
152 | printk(KERN_DEBUG "%s\n", line); | |
153 | count -= 8; | |
154 | buf += 8; | |
155 | } | |
156 | ||
157 | if (count > 0) { | |
158 | memset (line, 32, 44); | |
159 | ppp_print_hex (line, buf, count); | |
160 | ppp_print_char (&line[8 * 3], buf, count); | |
161 | printk(KERN_DEBUG "%s\n", line); | |
162 | } | |
163 | } | |
164 | ||
165 | ||
166 | /* | |
167 | * Routines implementing the synchronous PPP line discipline. | |
168 | */ | |
169 | ||
170 | /* | |
171 | * We have a potential race on dereferencing tty->disc_data, | |
172 | * because the tty layer provides no locking at all - thus one | |
173 | * cpu could be running ppp_synctty_receive while another | |
174 | * calls ppp_synctty_close, which zeroes tty->disc_data and | |
175 | * frees the memory that ppp_synctty_receive is using. The best | |
176 | * way to fix this is to use a rwlock in the tty struct, but for now | |
177 | * we use a single global rwlock for all ttys in ppp line discipline. | |
178 | * | |
179 | * FIXME: Fixed in tty_io nowdays. | |
180 | */ | |
181 | static DEFINE_RWLOCK(disc_data_lock); | |
182 | ||
183 | static struct syncppp *sp_get(struct tty_struct *tty) | |
184 | { | |
185 | struct syncppp *ap; | |
186 | ||
187 | read_lock(&disc_data_lock); | |
188 | ap = tty->disc_data; | |
189 | if (ap != NULL) | |
190 | atomic_inc(&ap->refcnt); | |
191 | read_unlock(&disc_data_lock); | |
192 | return ap; | |
193 | } | |
194 | ||
195 | static void sp_put(struct syncppp *ap) | |
196 | { | |
197 | if (atomic_dec_and_test(&ap->refcnt)) | |
198 | up(&ap->dead_sem); | |
199 | } | |
200 | ||
201 | /* | |
202 | * Called when a tty is put into sync-PPP line discipline. | |
203 | */ | |
204 | static int | |
205 | ppp_sync_open(struct tty_struct *tty) | |
206 | { | |
207 | struct syncppp *ap; | |
208 | int err; | |
209 | ||
dd00cc48 | 210 | ap = kzalloc(sizeof(*ap), GFP_KERNEL); |
1da177e4 | 211 | err = -ENOMEM; |
cd228d54 | 212 | if (!ap) |
1da177e4 LT |
213 | goto out; |
214 | ||
215 | /* initialize the syncppp structure */ | |
1da177e4 LT |
216 | ap->tty = tty; |
217 | ap->mru = PPP_MRU; | |
218 | spin_lock_init(&ap->xmit_lock); | |
219 | spin_lock_init(&ap->recv_lock); | |
220 | ap->xaccm[0] = ~0U; | |
221 | ap->xaccm[3] = 0x60000000U; | |
222 | ap->raccm = ~0U; | |
223 | ||
224 | skb_queue_head_init(&ap->rqueue); | |
225 | tasklet_init(&ap->tsk, ppp_sync_process, (unsigned long) ap); | |
226 | ||
227 | atomic_set(&ap->refcnt, 1); | |
228 | init_MUTEX_LOCKED(&ap->dead_sem); | |
229 | ||
230 | ap->chan.private = ap; | |
231 | ap->chan.ops = &sync_ops; | |
232 | ap->chan.mtu = PPP_MRU; | |
233 | ap->chan.hdrlen = 2; /* for A/C bytes */ | |
234 | err = ppp_register_channel(&ap->chan); | |
235 | if (err) | |
236 | goto out_free; | |
237 | ||
238 | tty->disc_data = ap; | |
33f0f88f | 239 | tty->receive_room = 65536; |
1da177e4 LT |
240 | return 0; |
241 | ||
242 | out_free: | |
243 | kfree(ap); | |
244 | out: | |
245 | return err; | |
246 | } | |
247 | ||
248 | /* | |
249 | * Called when the tty is put into another line discipline | |
250 | * or it hangs up. We have to wait for any cpu currently | |
251 | * executing in any of the other ppp_synctty_* routines to | |
252 | * finish before we can call ppp_unregister_channel and free | |
253 | * the syncppp struct. This routine must be called from | |
254 | * process context, not interrupt or softirq context. | |
255 | */ | |
256 | static void | |
257 | ppp_sync_close(struct tty_struct *tty) | |
258 | { | |
259 | struct syncppp *ap; | |
260 | ||
261 | write_lock_irq(&disc_data_lock); | |
262 | ap = tty->disc_data; | |
263 | tty->disc_data = NULL; | |
264 | write_unlock_irq(&disc_data_lock); | |
cd228d54 | 265 | if (!ap) |
1da177e4 LT |
266 | return; |
267 | ||
268 | /* | |
269 | * We have now ensured that nobody can start using ap from now | |
270 | * on, but we have to wait for all existing users to finish. | |
271 | * Note that ppp_unregister_channel ensures that no calls to | |
272 | * our channel ops (i.e. ppp_sync_send/ioctl) are in progress | |
273 | * by the time it returns. | |
274 | */ | |
275 | if (!atomic_dec_and_test(&ap->refcnt)) | |
276 | down(&ap->dead_sem); | |
277 | tasklet_kill(&ap->tsk); | |
278 | ||
279 | ppp_unregister_channel(&ap->chan); | |
280 | skb_queue_purge(&ap->rqueue); | |
cd228d54 | 281 | if (ap->tpkt) |
1da177e4 LT |
282 | kfree_skb(ap->tpkt); |
283 | kfree(ap); | |
284 | } | |
285 | ||
286 | /* | |
287 | * Called on tty hangup in process context. | |
288 | * | |
289 | * Wait for I/O to driver to complete and unregister PPP channel. | |
290 | * This is already done by the close routine, so just call that. | |
291 | */ | |
292 | static int ppp_sync_hangup(struct tty_struct *tty) | |
293 | { | |
294 | ppp_sync_close(tty); | |
295 | return 0; | |
296 | } | |
297 | ||
298 | /* | |
299 | * Read does nothing - no data is ever available this way. | |
300 | * Pppd reads and writes packets via /dev/ppp instead. | |
301 | */ | |
302 | static ssize_t | |
303 | ppp_sync_read(struct tty_struct *tty, struct file *file, | |
304 | unsigned char __user *buf, size_t count) | |
305 | { | |
306 | return -EAGAIN; | |
307 | } | |
308 | ||
309 | /* | |
310 | * Write on the tty does nothing, the packets all come in | |
311 | * from the ppp generic stuff. | |
312 | */ | |
313 | static ssize_t | |
314 | ppp_sync_write(struct tty_struct *tty, struct file *file, | |
315 | const unsigned char *buf, size_t count) | |
316 | { | |
317 | return -EAGAIN; | |
318 | } | |
319 | ||
320 | static int | |
321 | ppp_synctty_ioctl(struct tty_struct *tty, struct file *file, | |
322 | unsigned int cmd, unsigned long arg) | |
323 | { | |
324 | struct syncppp *ap = sp_get(tty); | |
325 | int __user *p = (int __user *)arg; | |
326 | int err, val; | |
327 | ||
cd228d54 | 328 | if (!ap) |
1da177e4 LT |
329 | return -ENXIO; |
330 | err = -EFAULT; | |
331 | switch (cmd) { | |
332 | case PPPIOCGCHAN: | |
333 | err = -ENXIO; | |
cd228d54 | 334 | if (!ap) |
1da177e4 LT |
335 | break; |
336 | err = -EFAULT; | |
337 | if (put_user(ppp_channel_index(&ap->chan), p)) | |
338 | break; | |
339 | err = 0; | |
340 | break; | |
341 | ||
342 | case PPPIOCGUNIT: | |
343 | err = -ENXIO; | |
cd228d54 | 344 | if (!ap) |
1da177e4 LT |
345 | break; |
346 | err = -EFAULT; | |
347 | if (put_user(ppp_unit_number(&ap->chan), p)) | |
348 | break; | |
349 | err = 0; | |
350 | break; | |
351 | ||
1da177e4 LT |
352 | case TCFLSH: |
353 | /* flush our buffers and the serial port's buffer */ | |
354 | if (arg == TCIOFLUSH || arg == TCOFLUSH) | |
355 | ppp_sync_flush_output(ap); | |
d0127539 | 356 | err = tty_perform_flush(tty, arg); |
1da177e4 LT |
357 | break; |
358 | ||
359 | case FIONREAD: | |
360 | val = 0; | |
361 | if (put_user(val, p)) | |
362 | break; | |
363 | err = 0; | |
364 | break; | |
365 | ||
366 | default: | |
d0127539 AC |
367 | err = tty_mode_ioctl(tty, file, cmd, arg); |
368 | break; | |
1da177e4 LT |
369 | } |
370 | ||
371 | sp_put(ap); | |
372 | return err; | |
373 | } | |
374 | ||
375 | /* No kernel lock - fine */ | |
376 | static unsigned int | |
377 | ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait) | |
378 | { | |
379 | return 0; | |
380 | } | |
381 | ||
1da177e4 LT |
382 | /* |
383 | * This can now be called from hard interrupt level as well | |
384 | * as soft interrupt level or mainline. | |
385 | */ | |
386 | static void | |
387 | ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf, | |
388 | char *cflags, int count) | |
389 | { | |
390 | struct syncppp *ap = sp_get(tty); | |
391 | unsigned long flags; | |
392 | ||
cd228d54 | 393 | if (!ap) |
1da177e4 LT |
394 | return; |
395 | spin_lock_irqsave(&ap->recv_lock, flags); | |
396 | ppp_sync_input(ap, buf, cflags, count); | |
397 | spin_unlock_irqrestore(&ap->recv_lock, flags); | |
b03efcfb | 398 | if (!skb_queue_empty(&ap->rqueue)) |
1da177e4 LT |
399 | tasklet_schedule(&ap->tsk); |
400 | sp_put(ap); | |
401 | if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) | |
402 | && tty->driver->unthrottle) | |
403 | tty->driver->unthrottle(tty); | |
404 | } | |
405 | ||
406 | static void | |
407 | ppp_sync_wakeup(struct tty_struct *tty) | |
408 | { | |
409 | struct syncppp *ap = sp_get(tty); | |
410 | ||
411 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); | |
cd228d54 | 412 | if (!ap) |
1da177e4 LT |
413 | return; |
414 | set_bit(XMIT_WAKEUP, &ap->xmit_flags); | |
415 | tasklet_schedule(&ap->tsk); | |
416 | sp_put(ap); | |
417 | } | |
418 | ||
419 | ||
420 | static struct tty_ldisc ppp_sync_ldisc = { | |
421 | .owner = THIS_MODULE, | |
422 | .magic = TTY_LDISC_MAGIC, | |
423 | .name = "pppsync", | |
424 | .open = ppp_sync_open, | |
425 | .close = ppp_sync_close, | |
426 | .hangup = ppp_sync_hangup, | |
427 | .read = ppp_sync_read, | |
428 | .write = ppp_sync_write, | |
429 | .ioctl = ppp_synctty_ioctl, | |
430 | .poll = ppp_sync_poll, | |
1da177e4 LT |
431 | .receive_buf = ppp_sync_receive, |
432 | .write_wakeup = ppp_sync_wakeup, | |
433 | }; | |
434 | ||
435 | static int __init | |
436 | ppp_sync_init(void) | |
437 | { | |
438 | int err; | |
439 | ||
440 | err = tty_register_ldisc(N_SYNC_PPP, &ppp_sync_ldisc); | |
441 | if (err != 0) | |
442 | printk(KERN_ERR "PPP_sync: error %d registering line disc.\n", | |
443 | err); | |
444 | return err; | |
445 | } | |
446 | ||
447 | /* | |
448 | * The following routines provide the PPP channel interface. | |
449 | */ | |
450 | static int | |
451 | ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg) | |
452 | { | |
453 | struct syncppp *ap = chan->private; | |
454 | int err, val; | |
455 | u32 accm[8]; | |
456 | void __user *argp = (void __user *)arg; | |
457 | u32 __user *p = argp; | |
458 | ||
459 | err = -EFAULT; | |
460 | switch (cmd) { | |
461 | case PPPIOCGFLAGS: | |
462 | val = ap->flags | ap->rbits; | |
463 | if (put_user(val, (int __user *) argp)) | |
464 | break; | |
465 | err = 0; | |
466 | break; | |
467 | case PPPIOCSFLAGS: | |
468 | if (get_user(val, (int __user *) argp)) | |
469 | break; | |
470 | ap->flags = val & ~SC_RCV_BITS; | |
471 | spin_lock_irq(&ap->recv_lock); | |
472 | ap->rbits = val & SC_RCV_BITS; | |
473 | spin_unlock_irq(&ap->recv_lock); | |
474 | err = 0; | |
475 | break; | |
476 | ||
477 | case PPPIOCGASYNCMAP: | |
478 | if (put_user(ap->xaccm[0], p)) | |
479 | break; | |
480 | err = 0; | |
481 | break; | |
482 | case PPPIOCSASYNCMAP: | |
483 | if (get_user(ap->xaccm[0], p)) | |
484 | break; | |
485 | err = 0; | |
486 | break; | |
487 | ||
488 | case PPPIOCGRASYNCMAP: | |
489 | if (put_user(ap->raccm, p)) | |
490 | break; | |
491 | err = 0; | |
492 | break; | |
493 | case PPPIOCSRASYNCMAP: | |
494 | if (get_user(ap->raccm, p)) | |
495 | break; | |
496 | err = 0; | |
497 | break; | |
498 | ||
499 | case PPPIOCGXASYNCMAP: | |
500 | if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm))) | |
501 | break; | |
502 | err = 0; | |
503 | break; | |
504 | case PPPIOCSXASYNCMAP: | |
505 | if (copy_from_user(accm, argp, sizeof(accm))) | |
506 | break; | |
507 | accm[2] &= ~0x40000000U; /* can't escape 0x5e */ | |
508 | accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */ | |
509 | memcpy(ap->xaccm, accm, sizeof(ap->xaccm)); | |
510 | err = 0; | |
511 | break; | |
512 | ||
513 | case PPPIOCGMRU: | |
514 | if (put_user(ap->mru, (int __user *) argp)) | |
515 | break; | |
516 | err = 0; | |
517 | break; | |
518 | case PPPIOCSMRU: | |
519 | if (get_user(val, (int __user *) argp)) | |
520 | break; | |
521 | if (val < PPP_MRU) | |
522 | val = PPP_MRU; | |
523 | ap->mru = val; | |
524 | err = 0; | |
525 | break; | |
526 | ||
527 | default: | |
528 | err = -ENOTTY; | |
529 | } | |
530 | return err; | |
531 | } | |
532 | ||
533 | /* | |
534 | * This is called at softirq level to deliver received packets | |
535 | * to the ppp_generic code, and to tell the ppp_generic code | |
536 | * if we can accept more output now. | |
537 | */ | |
538 | static void ppp_sync_process(unsigned long arg) | |
539 | { | |
540 | struct syncppp *ap = (struct syncppp *) arg; | |
541 | struct sk_buff *skb; | |
542 | ||
543 | /* process received packets */ | |
544 | while ((skb = skb_dequeue(&ap->rqueue)) != NULL) { | |
545 | if (skb->len == 0) { | |
546 | /* zero length buffers indicate error */ | |
547 | ppp_input_error(&ap->chan, 0); | |
548 | kfree_skb(skb); | |
549 | } | |
550 | else | |
551 | ppp_input(&ap->chan, skb); | |
552 | } | |
553 | ||
554 | /* try to push more stuff out */ | |
555 | if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_sync_push(ap)) | |
556 | ppp_output_wakeup(&ap->chan); | |
557 | } | |
558 | ||
559 | /* | |
560 | * Procedures for encapsulation and framing. | |
561 | */ | |
562 | ||
563 | struct sk_buff* | |
564 | ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *skb) | |
565 | { | |
566 | int proto; | |
567 | unsigned char *data; | |
568 | int islcp; | |
569 | ||
570 | data = skb->data; | |
571 | proto = (data[0] << 8) + data[1]; | |
572 | ||
573 | /* LCP packets with codes between 1 (configure-request) | |
574 | * and 7 (code-reject) must be sent as though no options | |
575 | * have been negotiated. | |
576 | */ | |
577 | islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7; | |
578 | ||
579 | /* compress protocol field if option enabled */ | |
580 | if (data[0] == 0 && (ap->flags & SC_COMP_PROT) && !islcp) | |
581 | skb_pull(skb,1); | |
582 | ||
583 | /* prepend address/control fields if necessary */ | |
584 | if ((ap->flags & SC_COMP_AC) == 0 || islcp) { | |
585 | if (skb_headroom(skb) < 2) { | |
586 | struct sk_buff *npkt = dev_alloc_skb(skb->len + 2); | |
587 | if (npkt == NULL) { | |
588 | kfree_skb(skb); | |
589 | return NULL; | |
590 | } | |
591 | skb_reserve(npkt,2); | |
d626f62b ACM |
592 | skb_copy_from_linear_data(skb, |
593 | skb_put(npkt, skb->len), skb->len); | |
1da177e4 LT |
594 | kfree_skb(skb); |
595 | skb = npkt; | |
596 | } | |
597 | skb_push(skb,2); | |
598 | skb->data[0] = PPP_ALLSTATIONS; | |
599 | skb->data[1] = PPP_UI; | |
600 | } | |
601 | ||
602 | ap->last_xmit = jiffies; | |
603 | ||
604 | if (skb && ap->flags & SC_LOG_OUTPKT) | |
605 | ppp_print_buffer ("send buffer", skb->data, skb->len); | |
606 | ||
607 | return skb; | |
608 | } | |
609 | ||
610 | /* | |
611 | * Transmit-side routines. | |
612 | */ | |
613 | ||
614 | /* | |
615 | * Send a packet to the peer over an sync tty line. | |
616 | * Returns 1 iff the packet was accepted. | |
617 | * If the packet was not accepted, we will call ppp_output_wakeup | |
618 | * at some later time. | |
619 | */ | |
620 | static int | |
621 | ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb) | |
622 | { | |
623 | struct syncppp *ap = chan->private; | |
624 | ||
625 | ppp_sync_push(ap); | |
626 | ||
627 | if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags)) | |
628 | return 0; /* already full */ | |
629 | skb = ppp_sync_txmunge(ap, skb); | |
630 | if (skb != NULL) | |
631 | ap->tpkt = skb; | |
632 | else | |
633 | clear_bit(XMIT_FULL, &ap->xmit_flags); | |
634 | ||
635 | ppp_sync_push(ap); | |
636 | return 1; | |
637 | } | |
638 | ||
639 | /* | |
640 | * Push as much data as possible out to the tty. | |
641 | */ | |
642 | static int | |
643 | ppp_sync_push(struct syncppp *ap) | |
644 | { | |
645 | int sent, done = 0; | |
646 | struct tty_struct *tty = ap->tty; | |
647 | int tty_stuffed = 0; | |
648 | ||
649 | if (!spin_trylock_bh(&ap->xmit_lock)) | |
650 | return 0; | |
651 | for (;;) { | |
652 | if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags)) | |
653 | tty_stuffed = 0; | |
cd228d54 | 654 | if (!tty_stuffed && ap->tpkt) { |
1da177e4 LT |
655 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
656 | sent = tty->driver->write(tty, ap->tpkt->data, ap->tpkt->len); | |
657 | if (sent < 0) | |
658 | goto flush; /* error, e.g. loss of CD */ | |
659 | if (sent < ap->tpkt->len) { | |
660 | tty_stuffed = 1; | |
661 | } else { | |
662 | kfree_skb(ap->tpkt); | |
663 | ap->tpkt = NULL; | |
664 | clear_bit(XMIT_FULL, &ap->xmit_flags); | |
665 | done = 1; | |
666 | } | |
667 | continue; | |
668 | } | |
669 | /* haven't made any progress */ | |
670 | spin_unlock_bh(&ap->xmit_lock); | |
671 | if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) | |
cd228d54 | 672 | || (!tty_stuffed && ap->tpkt))) |
1da177e4 LT |
673 | break; |
674 | if (!spin_trylock_bh(&ap->xmit_lock)) | |
675 | break; | |
676 | } | |
677 | return done; | |
678 | ||
679 | flush: | |
cd228d54 | 680 | if (ap->tpkt) { |
1da177e4 LT |
681 | kfree_skb(ap->tpkt); |
682 | ap->tpkt = NULL; | |
683 | clear_bit(XMIT_FULL, &ap->xmit_flags); | |
684 | done = 1; | |
685 | } | |
686 | spin_unlock_bh(&ap->xmit_lock); | |
687 | return done; | |
688 | } | |
689 | ||
690 | /* | |
691 | * Flush output from our internal buffers. | |
692 | * Called for the TCFLSH ioctl. | |
693 | */ | |
694 | static void | |
695 | ppp_sync_flush_output(struct syncppp *ap) | |
696 | { | |
697 | int done = 0; | |
698 | ||
699 | spin_lock_bh(&ap->xmit_lock); | |
700 | if (ap->tpkt != NULL) { | |
701 | kfree_skb(ap->tpkt); | |
702 | ap->tpkt = NULL; | |
703 | clear_bit(XMIT_FULL, &ap->xmit_flags); | |
704 | done = 1; | |
705 | } | |
706 | spin_unlock_bh(&ap->xmit_lock); | |
707 | if (done) | |
708 | ppp_output_wakeup(&ap->chan); | |
709 | } | |
710 | ||
711 | /* | |
712 | * Receive-side routines. | |
713 | */ | |
714 | ||
715 | /* called when the tty driver has data for us. | |
716 | * | |
717 | * Data is frame oriented: each call to ppp_sync_input is considered | |
718 | * a whole frame. If the 1st flag byte is non-zero then the whole | |
719 | * frame is considered to be in error and is tossed. | |
720 | */ | |
721 | static void | |
722 | ppp_sync_input(struct syncppp *ap, const unsigned char *buf, | |
723 | char *flags, int count) | |
724 | { | |
725 | struct sk_buff *skb; | |
726 | unsigned char *p; | |
727 | ||
728 | if (count == 0) | |
729 | return; | |
730 | ||
731 | if (ap->flags & SC_LOG_INPKT) | |
732 | ppp_print_buffer ("receive buffer", buf, count); | |
733 | ||
734 | /* stuff the chars in the skb */ | |
cd228d54 JP |
735 | skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2); |
736 | if (!skb) { | |
1da177e4 LT |
737 | printk(KERN_ERR "PPPsync: no memory (input pkt)\n"); |
738 | goto err; | |
739 | } | |
740 | /* Try to get the payload 4-byte aligned */ | |
741 | if (buf[0] != PPP_ALLSTATIONS) | |
742 | skb_reserve(skb, 2 + (buf[0] & 1)); | |
743 | ||
cd228d54 | 744 | if (flags && *flags) { |
1da177e4 LT |
745 | /* error flag set, ignore frame */ |
746 | goto err; | |
747 | } else if (count > skb_tailroom(skb)) { | |
748 | /* packet overflowed MRU */ | |
749 | goto err; | |
750 | } | |
751 | ||
752 | p = skb_put(skb, count); | |
753 | memcpy(p, buf, count); | |
754 | ||
755 | /* strip address/control field if present */ | |
756 | p = skb->data; | |
757 | if (p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) { | |
758 | /* chop off address/control */ | |
759 | if (skb->len < 3) | |
760 | goto err; | |
761 | p = skb_pull(skb, 2); | |
762 | } | |
763 | ||
764 | /* decompress protocol field if compressed */ | |
765 | if (p[0] & 1) { | |
766 | /* protocol is compressed */ | |
767 | skb_push(skb, 1)[0] = 0; | |
768 | } else if (skb->len < 2) | |
769 | goto err; | |
770 | ||
771 | /* queue the frame to be processed */ | |
772 | skb_queue_tail(&ap->rqueue, skb); | |
773 | return; | |
774 | ||
775 | err: | |
776 | /* queue zero length packet as error indication */ | |
777 | if (skb || (skb = dev_alloc_skb(0))) { | |
778 | skb_trim(skb, 0); | |
779 | skb_queue_tail(&ap->rqueue, skb); | |
780 | } | |
781 | } | |
782 | ||
783 | static void __exit | |
784 | ppp_sync_cleanup(void) | |
785 | { | |
64ccd715 | 786 | if (tty_unregister_ldisc(N_SYNC_PPP) != 0) |
1da177e4 LT |
787 | printk(KERN_ERR "failed to unregister Sync PPP line discipline\n"); |
788 | } | |
789 | ||
790 | module_init(ppp_sync_init); | |
791 | module_exit(ppp_sync_cleanup); | |
792 | MODULE_LICENSE("GPL"); | |
793 | MODULE_ALIAS_LDISC(N_SYNC_PPP); |