update for 2.3.11
[ppp.git] / linux / ppp.c
1 /*  PPP for Linux
2  *
3  *  Michael Callahan <callahan@maths.ox.ac.uk>
4  *  Al Longyear <longyear@netcom.com>
5  *  Extensively rewritten by Paul Mackerras <paulus@cs.anu.edu.au>
6  *
7  *  ==FILEVERSION 990910==
8  *
9  *  NOTE TO MAINTAINERS:
10  *     If you modify this file at all, please set the number above to the
11  *     date of the modification as YYMMDD (year month day).
12  *     ppp.c is shipped with a PPP distribution as well as with the kernel;
13  *     if everyone increases the FILEVERSION number above, then scripts
14  *     can do the right thing when deciding whether to install a new ppp.c
15  *     file.  Don't change the format of that line otherwise, so the
16  *     installation script can recognize it.
17  */
18
19 /*
20    Sources:
21
22    slip.c
23
24    RFC1331: The Point-to-Point Protocol (PPP) for the Transmission of
25    Multi-protocol Datagrams over Point-to-Point Links
26
27    RFC1332: IPCP
28
29    ppp-2.0
30
31    Flags for this module (any combination is acceptable for testing.):
32
33    OPTIMIZE_FLAG_TIME - Number of jiffies to force sending of leading flag
34                         character. This is normally set to ((HZ * 3) / 2).
35                         This is 1.5 seconds. If zero then the leading
36                         flag is always sent.
37
38    CHECK_CHARACTERS   - Enable the checking on all received characters for
39                         8 data bits, no parity. This adds a small amount of
40                         processing for each received character.
41 */
42
43 #define OPTIMIZE_FLAG_TIME      ((HZ * 3)/2)
44 #define CHECK_CHARACTERS        1
45
46 #define PPP_MAX_RCV_QLEN        32      /* max # frames we queue up for pppd */
47
48 /* $Id: ppp.c,v 1.33 1999/12/23 01:48:45 paulus Exp $ */
49
50 #include <linux/version.h>
51 #include <linux/config.h>
52 #include <linux/module.h>
53 #include <linux/kernel.h>
54 #include <linux/sched.h>
55 #include <linux/types.h>
56 #include <linux/fcntl.h>
57 #include <linux/interrupt.h>
58 #include <linux/ptrace.h>
59
60 /* a macro to generate linux version number codes */
61 #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
62
63 #if LINUX_VERSION_CODE < VERSION(2,1,14)
64 #include <linux/ioport.h>
65 #endif
66
67 #if LINUX_VERSION_CODE >= VERSION(2,1,23)
68 #include <linux/poll.h>
69 #endif
70
71 #include <linux/in.h>
72 #include <linux/malloc.h>
73 #include <linux/tty.h>
74 #include <linux/errno.h>
75 #include <linux/sched.h>        /* to get the struct task_struct */
76 #include <linux/string.h>       /* used in new tty drivers */
77 #include <linux/signal.h>       /* used in new tty drivers */
78 #include <asm/system.h>
79 #include <asm/bitops.h>
80 #include <linux/if.h>
81 #include <linux/if_ether.h>
82 #include <linux/netdevice.h>
83 #include <linux/skbuff.h>
84 #include <linux/inet.h>
85 #include <linux/ioctl.h>
86 #include <linux/ip.h>
87 #include <linux/tcp.h>
88 #include <linux/if_arp.h>
89 #include <net/slhc_vj.h>
90
91 #define fcstab  ppp_crc16_table         /* Name of the table in the kernel */
92 #include <linux/ppp_defs.h>
93
94 #include <linux/socket.h>
95 #include <linux/if_ppp.h>
96 #include <linux/if_pppvar.h>
97 #include <linux/ppp-comp.h>
98
99 #ifdef CONFIG_KMOD
100 #include <linux/kmod.h>
101 #endif
102 #ifdef CONFIG_KERNELD
103 #include <linux/kerneld.h>
104 #endif
105
106 #undef PPP_VERSION
107 #define PPP_VERSION     "2.3.11"
108
109 #if LINUX_VERSION_CODE >= VERSION(2,1,4)
110
111 #if LINUX_VERSION_CODE >= VERSION(2,1,5)
112 #include <asm/uaccess.h>
113 #else
114 #include <asm/segment.h>
115 #endif
116
117 #define GET_USER        get_user
118 #define PUT_USER        put_user
119 #define COPY_FROM_USER  copy_from_user
120 #define COPY_TO_USER    copy_to_user
121
122 #else  /* 2.0.x and 2.1.x before 2.1.4 */
123
124 #define GET_USER(val, src)      \
125         (verify_area(VERIFY_READ, src, sizeof(*src))? -EFAULT: \
126          ((val) = get_user(src), 0))
127 #define PUT_USER(val, dst)      \
128         (verify_area(VERIFY_WRITE, dst, sizeof(*dst))? -EFAULT: \
129          (put_user(val, dst), 0))
130 #define COPY_FROM_USER(dst, src, size)  \
131         (verify_area(VERIFY_READ, src, size)? -EFAULT: \
132          (memcpy_fromfs(dst, src, size), 0))
133 #define COPY_TO_USER(dst, src, size)    \
134         (verify_area(VERIFY_WRITE, dst, size)? -EFAULT: \
135          (memcpy_tofs(dst, src, size), 0))
136
137 #endif /* < 2.1.4 */
138
139 #if LINUX_VERSION_CODE < VERSION(2,1,37)
140 #define test_and_set_bit(nr, addr)      set_bit(nr, addr)
141 #endif
142
143 #if LINUX_VERSION_CODE < VERSION(2,1,25)
144 #define net_device_stats        enet_statistics
145 #endif
146
147 #if LINUX_VERSION_CODE < VERSION(2,1,57)
148 #define signal_pending(tsk)     ((tsk)->signal & ~(tsk)->blocked)
149 #endif
150
151 #if LINUX_VERSION_CODE < VERSION(2,1,60)
152 typedef int             rw_ret_t;
153 typedef unsigned int    rw_count_t;
154 #else
155 typedef ssize_t         rw_ret_t;
156 typedef size_t          rw_count_t;
157 #endif
158
159 #if LINUX_VERSION_CODE < VERSION(2,1,86)
160 #define KFREE_SKB(s)    dev_kfree_skb((s), FREE_WRITE)
161 #else
162 #define KFREE_SKB(s)    kfree_skb(s)
163 #endif
164
165 #if LINUX_VERSION_CODE < VERSION(2,1,15)
166 #define LIBERATE_SKB(s) ((s)->free = 1)
167 #else
168 #define LIBERATE_SKB(s) do { } while (0)
169 #endif
170
171 #if LINUX_VERSION_CODE < VERSION(2,1,95)
172 #define SUSER()         suser()
173 #else
174 #define SUSER()         capable(CAP_NET_ADMIN)
175 #endif
176
177 #if LINUX_VERSION_CODE < VERSION(2,2,0)
178 #define wmb()           mb()
179 #endif
180
181 /*
182  * Local functions
183  */
184
185 static int ppp_register_compressor (struct compressor *cp);
186 static void ppp_unregister_compressor (struct compressor *cp);
187
188 static void ppp_async_init(struct ppp *ppp);
189 static void ppp_async_release(struct ppp *ppp);
190 static int ppp_tty_sync_push(struct ppp *ppp);
191 static int ppp_tty_push(struct ppp *ppp);
192 static int ppp_async_encode(struct ppp *ppp);
193 static int ppp_async_send(struct ppp *, struct sk_buff *);
194 static int ppp_sync_send(struct ppp *, struct sk_buff *);
195 static void ppp_tty_flush_output(struct ppp *);
196
197 static int ppp_ioctl(struct ppp *, unsigned int, unsigned long);
198 static int ppp_set_compression (struct ppp *ppp, struct ppp_option_data *odp);
199 static void ppp_proto_ccp(struct ppp *ppp, __u8 *dp, int len, int rcvd);
200 static void ppp_ccp_closed(struct ppp *ppp);
201 static int ppp_receive_frame(struct ppp *, struct sk_buff *);
202 static void ppp_receive_error(struct ppp *ppp);
203 static void ppp_output_wakeup(struct ppp *ppp);
204 static void ppp_send_ctrl(struct ppp *ppp, struct sk_buff *skb);
205 static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
206 static void ppp_send_frames(struct ppp *ppp);
207 static struct sk_buff *ppp_vj_compress(struct ppp *ppp, struct sk_buff *skb);
208
209 static struct ppp *ppp_find (int pid_value);
210 static struct ppp *ppp_alloc (void);
211 static void ppp_generic_init(struct ppp *ppp);
212 static void ppp_release(struct ppp *ppp);
213 static void ppp_print_buffer (const char *, const __u8 *, int);
214 static struct compressor *find_compressor (int type);
215
216 #ifndef OPTIMIZE_FLAG_TIME
217 #define OPTIMIZE_FLAG_TIME      0
218 #endif
219
220 /*
221  * Parameters which may be changed via insmod.
222  */
223
224 static int  flag_time = OPTIMIZE_FLAG_TIME;
225 #if LINUX_VERSION_CODE >= VERSION(2,1,19) 
226 MODULE_PARM(flag_time, "i");
227 #endif
228
229 #define CHECK_PPP_MAGIC(ppp)    do { \
230         if (ppp->magic != PPP_MAGIC) { \
231                 printk(ppp_magic_warn, ppp, __FILE__, __LINE__); \
232         } \
233 } while (0)
234 #define CHECK_PPP(a)    do { \
235         CHECK_PPP_MAGIC(ppp); \
236         if (!ppp->inuse) { \
237                 printk(ppp_warning, __LINE__); \
238                 return a; \
239         } \
240 } while (0)
241 #define CHECK_PPP_VOID() do { \
242         CHECK_PPP_MAGIC(ppp); \
243         if (!ppp->inuse) { \
244                 printk(ppp_warning, __LINE__); \
245                 return; \
246         } \
247 } while (0)
248
249 #define tty2ppp(tty)    ((struct ppp *) ((tty)->disc_data))
250 #define dev2ppp(dev)    ((struct ppp *) ((dev)->priv))
251 #define ppp2tty(ppp)    ((ppp)->tty)
252 #define ppp2dev(ppp)    (&(ppp)->dev)
253
254 static struct ppp *ppp_list = NULL;
255 static struct ppp *ppp_last = NULL;
256
257 /* Define these strings only once for all macro invocations */
258 static char ppp_warning[] = KERN_WARNING "PPP: ALERT! not INUSE! %d\n";
259 static char ppp_magic_warn[] = KERN_WARNING "bad magic for ppp %p at %s:%d\n";
260
261 static char szVersion[]         = PPP_VERSION;
262
263 #if LINUX_VERSION_CODE < VERSION(2,1,18)
264 static struct symbol_table ppp_syms = {
265 #include <linux/symtab_begin.h>
266         X(ppp_register_compressor),
267         X(ppp_unregister_compressor),
268 #include <linux/symtab_end.h>
269 };
270 #else
271 EXPORT_SYMBOL(ppp_register_compressor);
272 EXPORT_SYMBOL(ppp_unregister_compressor);
273 #endif
274
275 /*************************************************************
276  * LINE DISCIPLINE SUPPORT
277  *    The following code implements the PPP line discipline
278  *    and supports using PPP on an async serial line.
279  *************************************************************/
280
281 #define in_xmap(ppp,c)  (ppp->xmit_async_map[(c) >> 5] & (1 << ((c) & 0x1f)))
282 #define in_rmap(ppp,c)  ((((unsigned int) (__u8) (c)) < 0x20) && \
283                         ppp->recv_async_map & (1 << (c)))
284
285 /*
286  * TTY callbacks
287  */
288
289 static rw_ret_t ppp_tty_read(struct tty_struct *, struct file *, __u8 *,
290                              rw_count_t);
291 static rw_ret_t ppp_tty_write(struct tty_struct *, struct file *, const __u8 *,
292                               rw_count_t);
293 static int ppp_tty_ioctl(struct tty_struct *, struct file *, unsigned int,
294                          unsigned long);
295 #if LINUX_VERSION_CODE < VERSION(2,1,23)
296 static int ppp_tty_select(struct tty_struct *tty, struct inode *inode,
297                         struct file *filp, int sel_type, select_table * wait);
298 #else
299 static unsigned int ppp_tty_poll(struct tty_struct *tty, struct file *filp,
300                                  poll_table * wait);
301 #endif
302 static int ppp_tty_open (struct tty_struct *);
303 static void ppp_tty_close (struct tty_struct *);
304 static int ppp_tty_room (struct tty_struct *tty);
305 static void ppp_tty_receive (struct tty_struct *tty, const __u8 * cp,
306                              char *fp, int count);
307 static void ppp_tty_wakeup (struct tty_struct *tty);
308
309 __u16 ppp_crc16_table[256] =
310 {
311         0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
312         0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
313         0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
314         0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
315         0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
316         0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
317         0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
318         0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
319         0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
320         0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
321         0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
322         0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
323         0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
324         0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
325         0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
326         0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
327         0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
328         0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
329         0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
330         0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
331         0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
332         0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
333         0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
334         0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
335         0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
336         0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
337         0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
338         0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
339         0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
340         0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
341         0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
342         0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
343 };
344 #if LINUX_VERSION_CODE >= VERSION(2,1,18)
345 EXPORT_SYMBOL(ppp_crc16_table);
346 #endif
347
348 #ifdef CHECK_CHARACTERS
349 static __u32 paritytab[8] =
350 {
351         0x96696996, 0x69969669, 0x69969669, 0x96696996,
352         0x69969669, 0x96696996, 0x96696996, 0x69969669
353 };
354 #endif
355
356 /*
357  * This procedure is called at initialization time to register
358  * the PPP line discipline.
359  */
360 static int
361 ppp_first_time(void)
362 {
363         static struct tty_ldisc ppp_ldisc;
364         int    status;
365
366         printk(KERN_INFO
367                "PPP: version %s (demand dialling)"
368                "\n", szVersion);
369
370 #ifndef MODULE /* slhc module logic has its own copyright announcement */
371         printk(KERN_INFO
372                "TCP compression code copyright 1989 Regents of the "
373                "University of California\n");
374 #endif
375
376         /*
377          * Register the tty discipline
378          */
379         (void) memset (&ppp_ldisc, 0, sizeof (ppp_ldisc));
380         ppp_ldisc.magic         = TTY_LDISC_MAGIC;
381 #if LINUX_VERSION_CODE >= VERSION(2,1,28)
382         ppp_ldisc.name          = "ppp";
383 #endif
384         ppp_ldisc.open          = ppp_tty_open;
385         ppp_ldisc.close         = ppp_tty_close;
386         ppp_ldisc.read          = ppp_tty_read;
387         ppp_ldisc.write         = ppp_tty_write;
388         ppp_ldisc.ioctl         = ppp_tty_ioctl;
389 #if LINUX_VERSION_CODE < VERSION(2,1,23)
390         ppp_ldisc.select        = ppp_tty_select;
391 #else
392         ppp_ldisc.poll          = ppp_tty_poll;
393 #endif
394         ppp_ldisc.receive_room  = ppp_tty_room;
395         ppp_ldisc.receive_buf   = ppp_tty_receive;
396         ppp_ldisc.write_wakeup  = ppp_tty_wakeup;
397
398         status = tty_register_ldisc (N_PPP, &ppp_ldisc);
399         if (status == 0)
400                 printk(KERN_INFO "PPP line discipline registered.\n");
401         else
402                 printk(KERN_ERR "error registering line discipline: %d\n",
403                        status);
404         return status;
405 }
406
407
408 #ifndef MODULE
409 /*
410  * Called at boot time if the PPP driver is compiled into the kernel.
411  */
412 int
413 ppp_init(struct device *dev)
414 {
415         static int first_time = 1;
416         int    answer = 0;
417
418         if (first_time) {
419                 first_time = 0;
420                 answer     = ppp_first_time();
421 #if LINUX_VERSION_CODE < VERSION(2,1,18)
422                 if (answer == 0)
423                         (void) register_symtab(&ppp_syms);
424 #endif
425         }
426         if (answer == 0)
427                 answer = -ENODEV;
428         return answer;
429 }
430 #endif
431
432 /*
433  * Initialize the async-specific parts of the ppp structure.
434  */
435 static void
436 ppp_async_init(struct ppp *ppp)
437 {
438         ppp->escape = 0;
439         ppp->toss   = 0xE0;
440         ppp->tty_pushing = 0;
441
442         memset (ppp->xmit_async_map, 0, sizeof (ppp->xmit_async_map));
443         ppp->xmit_async_map[0] = 0xffffffff;
444         ppp->xmit_async_map[3] = 0x60000000;
445         ppp->recv_async_map    = 0xffffffff;
446
447         ppp->tpkt = NULL;
448         ppp->tfcs = PPP_INITFCS;
449         ppp->optr = ppp->obuf;
450         ppp->olim = ppp->obuf;
451
452         ppp->rpkt = NULL;
453         ppp->rfcs = PPP_INITFCS;
454
455         ppp->tty  = NULL;
456         ppp->backup_tty = NULL;
457
458         ppp->bytes_sent = 0;
459         ppp->bytes_rcvd = 0;
460 }
461
462 /*
463  * Clean up the async-specific parts of the ppp structure.
464  */
465 static void
466 ppp_async_release(struct ppp *ppp)
467 {
468         struct sk_buff *skb;
469
470         if ((skb = ppp->rpkt) != NULL)
471                 KFREE_SKB(skb);
472         ppp->rpkt = NULL;
473         if ((skb = ppp->tpkt) != NULL)
474                 KFREE_SKB(skb);
475         ppp->tpkt = NULL;
476 }
477
478 /*
479  * TTY callback.
480  *
481  * Called when the tty discipline is switched to PPP.
482  */
483
484 static int
485 ppp_tty_open (struct tty_struct *tty)
486 {
487         struct ppp *ppp;
488
489         /*
490          * Allocate a ppp structure to use.
491          */
492         tty->disc_data = NULL;
493         ppp = ppp_find(current->pid);
494         if (ppp != NULL) {
495                 /*
496                  * If we are taking over a ppp unit which is currently
497                  * connected to a loopback pty, there's not much to do.
498                  */
499                 CHECK_PPP(-EINVAL);
500
501         } else {
502                 ppp = ppp_alloc();
503                 if (ppp == NULL) {
504                         printk(KERN_ERR "ppp_alloc failed\n");
505                         return -ENFILE;
506                 }
507
508                 /*
509                  * Initialize the control block
510                  */
511                 ppp_generic_init(ppp);
512                 ppp_async_init(ppp);
513
514                 MOD_INC_USE_COUNT;
515         }
516
517         tty->disc_data = ppp;
518         ppp->tty       = tty;
519
520         /*
521          * Flush any pending characters in the driver
522          */
523         if (tty->driver.flush_buffer)
524                 tty->driver.flush_buffer (tty);
525
526         return ppp->line;
527 }
528
529 /*
530  * TTY callback.
531  *
532  * Called when the line discipline is changed to something
533  * else, the tty is closed, or the tty detects a hangup.
534  */
535
536 static void
537 ppp_tty_close (struct tty_struct *tty)
538 {
539         struct ppp *ppp = tty2ppp(tty);
540
541         if (ppp == NULL)
542                 return;
543         tty->disc_data = NULL;
544         if (ppp->magic != PPP_MAGIC) {
545                 printk(KERN_WARNING "ppp_tty_close: bogus\n");
546                 return;
547         }
548         if (!ppp->inuse) {
549                 printk(KERN_WARNING "ppp_tty_close: not inuse\n");
550                 ppp->tty = ppp->backup_tty = 0;
551                 return;
552         }
553         if (tty == ppp->backup_tty)
554                 ppp->backup_tty = 0;
555         if (tty != ppp->tty)
556                 return;
557         if (ppp->backup_tty) {
558                 ppp->tty = ppp->backup_tty;
559                 if (ppp_tty_push(ppp))
560                         ppp_output_wakeup(ppp);
561                 wake_up_interruptible(&ppp->read_wait);
562         } else {
563                 ppp->tty = 0;
564                 ppp->sc_xfer = 0;
565                 if (ppp->flags & SC_DEBUG)
566                         printk(KERN_INFO "ppp: channel %s closing.\n",
567                                ppp2dev(ppp)->name);
568
569                 ppp_async_release(ppp);
570                 ppp_release(ppp);
571                 MOD_DEC_USE_COUNT;
572         }
573 }
574
575 /*
576  * Read a PPP frame from the rcv_q list,
577  * waiting if necessary
578  */
579 static rw_ret_t
580 ppp_tty_read(struct tty_struct *tty, struct file *file, __u8 * buf,
581              rw_count_t nr)
582 {
583         struct ppp *ppp = tty2ppp (tty);
584         struct sk_buff *skb;
585         rw_ret_t len, err;
586
587         /*
588          * Validate the pointers
589          */
590         if (!ppp)
591                 return -EIO;
592         CHECK_PPP(-ENXIO);
593
594         /*
595          * Before we attempt to write the frame to the user, ensure that the
596          * user has access to the pages for the total buffer length.
597          */
598         err = verify_area(VERIFY_WRITE, buf, nr);
599         if (err != 0)
600                 return (err);
601
602         /*
603          * Wait for a frame to arrive if necessary.
604          * We increment the module use count so that the module
605          * can't go away while we're sleeping.
606          */
607         MOD_INC_USE_COUNT;
608         skb = NULL;
609         for (;;) {
610                 ppp = tty2ppp(tty);
611                 err = 0;
612                 if (!ppp || ppp->magic != PPP_MAGIC || !ppp->inuse
613                     || tty != ppp->tty)
614                         break;
615
616                 skb = skb_dequeue(&ppp->rcv_q);
617                 if (skb != 0)
618                         break;
619
620                 /*
621                  * If no frame is available, return -EAGAIN or wait.
622                  */
623                 err = -EAGAIN;
624                 if (file->f_flags & O_NONBLOCK)
625                         break;
626
627                 interruptible_sleep_on(&ppp->read_wait);
628                 err = -EINTR;
629                 if (signal_pending(current))
630                         break;
631         }
632         MOD_DEC_USE_COUNT;
633         if (skb == 0)
634                 return err;
635
636         /*
637          * Ensure that the frame will fit within the caller's buffer.
638          * If not, just discard the frame.
639          */
640         len = skb->len;
641         if (len > nr) {
642                 if (ppp->flags & SC_DEBUG)
643                         printk(KERN_DEBUG
644                                "ppp: read of %lu bytes too small for %ld "
645                                "frame\n", (unsigned long) nr, (long) len);
646                 ppp->stats.ppp_ierrors++;
647                 err = -EOVERFLOW;
648                 goto out;
649         }
650
651         /*
652          * Copy the received data from the buffer to the caller's area.
653          */
654         err = len;
655         if (COPY_TO_USER(buf, skb->data, len))
656                 err = -EFAULT;
657
658 out:
659         KFREE_SKB(skb);
660         return err;
661 }
662
663 /*
664  * Writing to a tty in ppp line discipline sends a PPP frame.
665  * Used by pppd to send control packets (LCP, etc.).
666  */
667 static rw_ret_t
668 ppp_tty_write(struct tty_struct *tty, struct file *file, const __u8 * data,
669               rw_count_t count)
670 {
671         struct ppp *ppp = tty2ppp (tty);
672         __u8 *new_data;
673         struct sk_buff *skb;
674
675         /*
676          * Verify the pointers.
677          */
678         if (!ppp)
679                 return -EIO;
680
681         if (ppp->magic != PPP_MAGIC)
682                 return -EIO;
683
684         CHECK_PPP(-ENXIO);
685
686         /*
687          * Ensure that the caller does not wish to send too much.
688          */
689         if (count > PPP_MTU + PPP_HDRLEN) {
690                 if (ppp->flags & SC_DEBUG)
691                         printk(KERN_WARNING
692                                "ppp_tty_write: truncating user packet "
693                                "from %lu to mtu %d\n", (unsigned long) count,
694                                PPP_MTU + PPP_HDRLEN);
695                 count = PPP_MTU + PPP_HDRLEN;
696         }
697
698         /*
699          * Allocate a buffer for the data and fetch it from the user space.
700          */
701         skb = alloc_skb(count, GFP_KERNEL);
702         if (skb == NULL) {
703                 printk(KERN_ERR "ppp_tty_write: no memory\n");
704                 return 0;
705         }
706         LIBERATE_SKB(skb);
707         new_data = skb_put(skb, count);
708
709         /*
710          * Retrieve the user's buffer
711          */
712         if (COPY_FROM_USER(new_data, data, count)) {
713                 KFREE_SKB(skb);
714                 return -EFAULT;
715         }
716
717         /*
718          * Send the frame
719          */
720         ppp_send_ctrl(ppp, skb);
721
722         return (rw_ret_t) count;
723 }
724
725 /*
726  * Process the IOCTL call for the tty device.
727  * Only the ioctls that relate to using ppp on async serial lines
728  * are processed here; the rest are handled by ppp_ioctl.
729  */
730 static int
731 ppp_tty_ioctl (struct tty_struct *tty, struct file * file,
732                unsigned int param2, unsigned long param3)
733 {
734         struct ppp *ppp = tty2ppp (tty);
735         register int temp_i = 0;
736         int error = -EFAULT;
737
738         /*
739          * Verify the status of the PPP device.
740          */
741         if (!ppp || ppp->magic != PPP_MAGIC || !ppp->inuse)
742                 return -ENXIO;
743
744         /*
745          * The user must have an euid of root to do these requests.
746          */
747         if (!SUSER())
748                 return -EPERM;
749
750         switch (param2) {
751         case PPPIOCGASYNCMAP:
752                 /*
753                  * Retrieve the transmit async map
754                  */
755                 if (PUT_USER(ppp->xmit_async_map[0], (int *) param3))
756                         break;
757                 error = 0;
758                 break;
759
760         case PPPIOCSASYNCMAP:
761                 /*
762                  * Set the transmit async map
763                  */
764                 if (GET_USER(temp_i, (int *) param3))
765                         break;
766                 ppp->xmit_async_map[0] = temp_i;
767                 if (ppp->flags & SC_DEBUG)
768                         printk(KERN_INFO
769                                "ppp_tty_ioctl: set xmit asyncmap %x\n",
770                                ppp->xmit_async_map[0]);
771                 error = 0;
772                 break;
773
774         case PPPIOCSRASYNCMAP:
775                 /*
776                  * Set the receive async map
777                  */
778                 if (GET_USER(temp_i, (int *) param3))
779                         break;
780                 ppp->recv_async_map = temp_i;
781                 if (ppp->flags & SC_DEBUG)
782                         printk(KERN_INFO
783                                "ppp_tty_ioctl: set rcv asyncmap %x\n",
784                                ppp->recv_async_map);
785                 error = 0;
786                 break;
787
788         case PPPIOCGXASYNCMAP:
789                 /*
790                  * Get the map of characters to be escaped on transmission.
791                  */
792                 if (COPY_TO_USER((void *) param3, ppp->xmit_async_map,
793                                  sizeof (ppp->xmit_async_map)))
794                         break;
795                 error = 0;
796                 break;
797
798         case PPPIOCSXASYNCMAP:
799                 /*
800                  * Set the map of characters to be escaped on transmission.
801                  */
802                 {
803                         __u32 temp_tbl[8];
804
805                         if (COPY_FROM_USER(temp_tbl, (void *) param3,
806                                            sizeof (temp_tbl)))
807                                 break;
808
809                         temp_tbl[1]  =  0x00000000;
810                         temp_tbl[2] &= ~0x40000000;
811                         temp_tbl[3] |=  0x60000000;
812
813                         memcpy(ppp->xmit_async_map, temp_tbl,
814                                sizeof (ppp->xmit_async_map));
815
816                         if (ppp->flags & SC_DEBUG)
817                                 printk(KERN_INFO
818                                        "ppp_tty_ioctl: set xasyncmap\n");
819                         error = 0;
820                 }
821                 break;
822
823         case PPPIOCXFERUNIT:
824                 /*
825                  * Set up this PPP unit to be used next time this
826                  * process sets a tty to PPP line discipline.
827                  */
828                 ppp->backup_tty = tty;
829                 ppp->sc_xfer = current->pid;
830                 error = 0;
831                 break;
832
833         case TCGETS:
834         case TCGETA:
835                 /*
836                  * Allow users to read, but not set, the serial port parameters
837                  */
838                 error = n_tty_ioctl (tty, file, param2, param3);
839                 break;
840
841         case TCFLSH:
842                 /*
843                  * Flush our buffers, then call the generic code to
844                  * flush the serial port's buffer.
845                  */
846                 if (param3 == TCIFLUSH || param3 == TCIOFLUSH) {
847                         struct sk_buff *skb;
848                         while ((skb = skb_dequeue(&ppp->rcv_q)) != NULL)
849                                 KFREE_SKB(skb);
850                 }
851                 if (param3 == TCIOFLUSH || param3 == TCOFLUSH)
852                         ppp_tty_flush_output(ppp);
853                 error = n_tty_ioctl (tty, file, param2, param3);
854                 break;
855
856         case FIONREAD:
857                 /*
858                  * Returns how many bytes are available for a read().
859                  */
860                 {
861                         unsigned long flags;
862                         struct sk_buff *skb;
863                         int count = 0;
864
865                         save_flags(flags);
866                         cli();
867                         skb = skb_peek(&ppp->rcv_q);
868                         if (skb != 0)
869                                 count = skb->len;
870                         restore_flags(flags);
871                         if (PUT_USER(count, (int *) param3))
872                                 break;
873                         error = 0;
874                 }
875                 break;
876
877         default:
878                 /*
879                  *  All other ioctl() events will come here.
880                  */
881                 error = ppp_ioctl(ppp, param2, param3);
882                 break;
883         }
884         return error;
885 }
886
887 /*
888  * TTY callback.
889  *
890  * Process the select() or poll() statement for the PPP device.
891  */
892
893 #if LINUX_VERSION_CODE < VERSION(2,1,23)
894 static int
895 ppp_tty_select(struct tty_struct *tty, struct inode *inode,
896                struct file *filp, int sel_type, select_table * wait)
897 {
898         struct ppp *ppp = tty2ppp(tty);
899         int result = 1;
900
901         /*
902          * Verify the status of the PPP device.
903          */
904         if (!ppp || tty != ppp->tty)
905                 return -EBADF;
906
907         CHECK_PPP(-EBADF);
908
909         switch (sel_type) {
910         case SEL_IN:
911                 /* The fd is readable if the receive queue isn't empty. */
912                 if (skb_peek(&ppp->rcv_q) != NULL)
913                         break;
914                 /* fall through */
915         case SEL_EX:
916                 /* Check for exceptions or read errors. */
917                 /* Is this a pty link and the remote disconnected? */
918                 if (tty->flags & (1 << TTY_OTHER_CLOSED))
919                         break;
920
921                 /* Is this a local link and the modem disconnected? */
922                 if (tty_hung_up_p (filp))
923                         break;
924
925                 select_wait(&ppp->read_wait, wait);
926                 result = 0;
927                 break;
928
929         case SEL_OUT:
930                 /* The fd is always writable. */
931                 break;
932         }
933         return result;
934 }
935
936 #else   /* 2.1.23 or later */
937
938 static unsigned int
939 ppp_tty_poll(struct tty_struct *tty, struct file *filp, poll_table * wait)
940 {
941         struct ppp *ppp = tty2ppp(tty);
942         unsigned int mask = 0;
943
944         if (ppp && ppp->magic == PPP_MAGIC && tty == ppp->tty) {
945                 CHECK_PPP(0);
946
947                 poll_wait(filp, &ppp->read_wait, wait);
948
949                 if (skb_peek(&ppp->rcv_q) != NULL)
950                         mask |= POLLIN | POLLRDNORM;
951                 if (tty->flags & (1 << TTY_OTHER_CLOSED)
952                     || tty_hung_up_p(filp))
953                         mask |= POLLHUP;
954                 mask |= POLLOUT | POLLWRNORM;
955         }
956         return mask;
957 }
958 #endif  /* >= 2.1.23 */
959
960 /*
961  * This function is called by the tty driver when the transmit buffer has
962  * additional space. It is used by the ppp code to continue to transmit
963  * the current buffer should the buffer have been partially sent.
964  */
965 static void
966 ppp_tty_wakeup (struct tty_struct *tty)
967 {
968         struct ppp *ppp = tty2ppp (tty);
969
970         tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
971         if (!ppp)
972                 return;
973         CHECK_PPP_VOID();
974         if (tty != ppp->tty)
975                 return;
976
977         if (ppp_tty_push(ppp))
978                 ppp_output_wakeup(ppp);
979 }
980
981 /*
982  * Send a packet to the peer over a synchronous tty line.
983  * All encoding and FCS are handled by hardware.
984  * Addr/Ctrl and Protocol field compression implemented.
985  * Returns -1 iff the packet could not be accepted at present,
986  * 0 if the packet was accepted but we can't accept another yet, or
987  * 1 if we can accept another packet immediately.
988  * If this procedure returns 0, ppp_output_wakeup will be called
989  * exactly once.
990  */
991 static int
992 ppp_sync_send(struct ppp *ppp, struct sk_buff *skb)
993 {
994         unsigned char *data;
995         int islcp;
996         
997         CHECK_PPP(0);
998
999         if (ppp->tpkt != NULL)
1000                 return -1;
1001         ppp->tpkt = skb;
1002
1003         data = ppp->tpkt->data;
1004         
1005         /*
1006          * LCP packets with code values between 1 (configure-reqest)
1007          * and 7 (code-reject) must be sent as though no options
1008          * had been negotiated.
1009          */
1010         islcp = PPP_PROTOCOL(data) == PPP_LCP
1011                 && 1 <= data[PPP_HDRLEN] && data[PPP_HDRLEN] <= 7;
1012
1013         /* only reset idle time for data packets */
1014         if (PPP_PROTOCOL(data) < 0x8000)
1015                 ppp->last_xmit = jiffies;
1016         ++ppp->stats.ppp_opackets;
1017         ppp->stats.ppp_ooctects += ppp->tpkt->len;
1018
1019         if ( !(data[2]) && (ppp->flags & SC_COMP_PROT) ) {
1020                 /* compress protocol field */
1021                 data[2] = data[1];
1022                 data[1] = data[0];
1023                 skb_pull(ppp->tpkt,1);
1024                 data = ppp->tpkt->data;
1025         }
1026         
1027         /*
1028          * Do address/control compression
1029          */
1030         if ((ppp->flags & SC_COMP_AC) && !islcp
1031             && PPP_ADDRESS(data) == PPP_ALLSTATIONS
1032             && PPP_CONTROL(data) == PPP_UI) {
1033                 /* strip addr and control field */
1034                 skb_pull(ppp->tpkt,2);
1035         }
1036
1037         return ppp_tty_sync_push(ppp);
1038 }
1039
1040 /*
1041  * Push a synchronous frame out to the tty.
1042  * Returns 1 if frame accepted (or discarded), 0 otherwise.
1043  */
1044 static int
1045 ppp_tty_sync_push(struct ppp *ppp)
1046 {
1047         int sent;
1048         struct tty_struct *tty = ppp2tty(ppp);
1049         unsigned long flags;
1050                 
1051         CHECK_PPP(0);
1052
1053         if (ppp->tpkt == NULL)
1054                 return 0;
1055                 
1056         /* prevent reentrancy with tty_pushing flag */          
1057         save_flags(flags);
1058         cli();
1059         if (ppp->tty_pushing) {
1060                 /* record wakeup attempt so we don't lose */
1061                 /* a wakeup call while doing push processing */
1062                 ppp->woke_up=1;
1063                 restore_flags(flags);
1064                 return 0;
1065         }
1066         ppp->tty_pushing = 1;
1067         restore_flags(flags);
1068         
1069         if (tty == NULL || tty->disc_data != (void *) ppp)
1070                 goto flush;
1071                 
1072         for(;;){
1073                 ppp->woke_up=0;
1074                 
1075                 /* Note: Sync driver accepts complete frame or nothing */
1076                 tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
1077                 sent = tty->driver.write(tty, 0, ppp->tpkt->data, ppp->tpkt->len);
1078                 if (sent < 0) {
1079                         /* write error (possible loss of CD) */
1080                         /* record error and discard current packet */
1081                         ppp->stats.ppp_oerrors++;
1082                         break;
1083                 }
1084                 ppp->stats.ppp_obytes += sent;
1085                 if (sent < ppp->tpkt->len) {
1086                         /* driver unable to accept frame just yet */
1087                         save_flags(flags);
1088                         cli();
1089                         if (ppp->woke_up) {
1090                                 /* wake up called while processing */
1091                                 /* try to send the frame again */
1092                                 restore_flags(flags);
1093                                 continue;
1094                         }
1095                         /* wait for wakeup callback to try send again */
1096                         ppp->tty_pushing = 0;
1097                         restore_flags(flags);
1098                         return 0;
1099                 }
1100                 break;
1101         }
1102 flush:  
1103         /* done with current packet (sent or discarded) */
1104         KFREE_SKB(ppp->tpkt);
1105         ppp->tpkt = 0;
1106         ppp->tty_pushing = 0;
1107         return 1;
1108 }
1109
1110 /*
1111  * Send a packet to the peer over an async tty line.
1112  * Returns -1 iff the packet could not be accepted at present,
1113  * 0 if the packet was accepted but we can't accept another yet, or
1114  * 1 if we can accept another packet immediately.
1115  * If this procedure returns 0, ppp_output_wakeup will be called
1116  * exactly once.
1117  */
1118 static int
1119 ppp_async_send(struct ppp *ppp, struct sk_buff *skb)
1120 {
1121         CHECK_PPP(0);
1122
1123         ppp_tty_push(ppp);
1124
1125         if (ppp->tpkt != NULL)
1126                 return -1;
1127         ppp->tpkt = skb;
1128         ppp->tpkt_pos = 0;
1129
1130         return ppp_tty_push(ppp);
1131 }
1132
1133 /*
1134  * Push as much data as possible out to the tty.
1135  * Returns 1 if we finished encoding the current frame, 0 otherwise.
1136  */
1137 static int
1138 ppp_tty_push(struct ppp *ppp)
1139 {
1140         int avail, sent, done = 0;
1141         struct tty_struct *tty = ppp2tty(ppp);
1142         
1143         if (ppp->flags & SC_SYNC) 
1144                 return ppp_tty_sync_push(ppp);
1145
1146         CHECK_PPP(0);
1147         if (ppp->tty_pushing) {
1148                 ppp->woke_up = 1;
1149                 return 0;
1150         }
1151         if (tty == NULL || tty->disc_data != (void *) ppp)
1152                 goto flush;
1153         while (ppp->optr < ppp->olim || ppp->tpkt != 0) {
1154                 ppp->tty_pushing = 1;
1155                 mb();
1156                 ppp->woke_up = 0;
1157                 avail = ppp->olim - ppp->optr;
1158                 if (avail > 0) {
1159                         tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
1160                         sent = tty->driver.write(tty, 0, ppp->optr, avail);
1161                         if (sent < 0)
1162                                 goto flush;     /* error, e.g. loss of CD */
1163                         ppp->stats.ppp_obytes += sent;
1164                         ppp->optr += sent;
1165                         if (sent < avail) {
1166                                 wmb();
1167                                 ppp->tty_pushing = 0;
1168                                 mb();
1169                                 if (ppp->woke_up)
1170                                         continue;
1171                                 return done;
1172                         }
1173                 }
1174                 if (ppp->tpkt != 0)
1175                         done = ppp_async_encode(ppp);
1176                 wmb();
1177                 ppp->tty_pushing = 0;
1178         }
1179         return done;
1180
1181 flush:
1182         ppp->tty_pushing = 1;
1183         mb();
1184         ppp->stats.ppp_oerrors++;
1185         if (ppp->tpkt != 0) {
1186                 KFREE_SKB(ppp->tpkt);
1187                 ppp->tpkt = 0;
1188                 done = 1;
1189         }
1190         ppp->optr = ppp->olim;
1191         wmb();
1192         ppp->tty_pushing = 0;
1193         return done;
1194 }
1195
1196 /*
1197  * Procedure to encode the data for async serial transmission.
1198  * Does octet stuffing (escaping) and address/control
1199  * and protocol compression.
1200  * Assumes ppp->opkt != 0 on entry.
1201  * Returns 1 if we finished the current frame, 0 otherwise.
1202  */
1203 static int
1204 ppp_async_encode(struct ppp *ppp)
1205 {
1206         int fcs, i, count, c;
1207         unsigned char *buf, *buflim;
1208         unsigned char *data;
1209         int islcp;
1210
1211         CHECK_PPP(0);
1212
1213         buf = ppp->obuf;
1214         ppp->olim = buf;
1215         ppp->optr = buf;
1216         i = ppp->tpkt_pos;
1217         data = ppp->tpkt->data;
1218         count = ppp->tpkt->len;
1219         fcs = ppp->tfcs;
1220
1221         /*
1222          * LCP packets with code values between 1 (configure-reqest)
1223          * and 7 (code-reject) must be sent as though no options
1224          * had been negotiated.
1225          */
1226         islcp = PPP_PROTOCOL(data) == PPP_LCP
1227                 && 1 <= data[PPP_HDRLEN] && data[PPP_HDRLEN] <= 7;
1228
1229         if (i == 0) {
1230                 /*
1231                  * Start of a new packet - insert the leading FLAG
1232                  * character if necessary.
1233                  */
1234                 if (islcp || flag_time == 0
1235                     || jiffies - ppp->last_xmit >= flag_time)
1236                         *buf++ = PPP_FLAG;
1237                 /* only reset idle time for data packets */
1238                 if (PPP_PROTOCOL(data) < 0x8000)
1239                         ppp->last_xmit = jiffies;
1240                 fcs = PPP_INITFCS;
1241                 ++ppp->stats.ppp_opackets;
1242                 ppp->stats.ppp_ooctects += count;
1243
1244                 /*
1245                  * Do address/control compression
1246                  */
1247                 if ((ppp->flags & SC_COMP_AC) != 0 && !islcp
1248                     && PPP_ADDRESS(data) == PPP_ALLSTATIONS
1249                     && PPP_CONTROL(data) == PPP_UI)
1250                         i += 2;
1251         }
1252
1253         /*
1254          * Once we put in the last byte, we need to put in the FCS
1255          * and closing flag, so make sure there is at least 7 bytes
1256          * of free space in the output buffer.
1257          */
1258         buflim = buf + OBUFSIZE - 6;
1259         while (i < count && buf < buflim) {
1260                 c = data[i++];
1261                 if (i == 3 && c == 0 && (ppp->flags & SC_COMP_PROT))
1262                         continue;       /* compress protocol field */
1263                 fcs = PPP_FCS(fcs, c);
1264                 if (in_xmap(ppp, c) || (islcp && c < 0x20)) {
1265                         *buf++ = PPP_ESCAPE;
1266                         c ^= 0x20;
1267                 }
1268                 *buf++ = c;
1269         }
1270
1271         if (i == count) {
1272                 /*
1273                  * We have finished the packet.  Add the FCS and flag.
1274                  */
1275                 fcs = ~fcs;
1276                 c = fcs & 0xff;
1277                 if (in_xmap(ppp, c) || (islcp && c < 0x20)) {
1278                         *buf++ = PPP_ESCAPE;
1279                         c ^= 0x20;
1280                 }
1281                 *buf++ = c;
1282                 c = (fcs >> 8) & 0xff;
1283                 if (in_xmap(ppp, c) || (islcp && c < 0x20)) {
1284                         *buf++ = PPP_ESCAPE;
1285                         c ^= 0x20;
1286                 }
1287                 *buf++ = c;
1288                 *buf++ = PPP_FLAG;
1289                 ppp->olim = buf;
1290
1291                 KFREE_SKB(ppp->tpkt);
1292                 ppp->tpkt = 0;
1293                 return 1;
1294         }
1295
1296         /*
1297          * Remember where we are up to in this packet.
1298          */
1299         ppp->olim = buf;
1300         ppp->tpkt_pos = i;
1301         ppp->tfcs = fcs;
1302         return 0;
1303 }
1304
1305 /*
1306  * Flush output from our internal buffers.
1307  * Called for the TCFLSH ioctl.
1308  */
1309 static void
1310 ppp_tty_flush_output(struct ppp *ppp)
1311 {
1312         struct sk_buff *skb;
1313         int done = 0;
1314
1315         while ((skb = skb_dequeue(&ppp->xmt_q)) != NULL)
1316                 KFREE_SKB(skb);
1317         ppp->tty_pushing = 1;
1318         mb();
1319         ppp->optr = ppp->olim;
1320         if (ppp->tpkt != NULL) {
1321                 KFREE_SKB(ppp->tpkt);
1322                 ppp->tpkt = 0;
1323                 done = 1;
1324         }
1325         wmb();
1326         ppp->tty_pushing = 0;
1327         if (done)
1328                 ppp_output_wakeup(ppp);
1329 }
1330
1331 /*
1332  * Callback function from tty driver. Return the amount of space left
1333  * in the receiver's buffer to decide if remote transmitter is to be
1334  * throttled.
1335  */
1336 static int
1337 ppp_tty_room (struct tty_struct *tty)
1338 {
1339         return 65536;       /* We can handle an infinite amount of data. :-) */
1340 }
1341
1342 /*
1343  * Callback function when data is available at the tty driver.
1344  */
1345 static void
1346 ppp_tty_receive (struct tty_struct *tty, const __u8 * data,
1347                  char *flags, int count)
1348 {
1349         register struct ppp *ppp = tty2ppp (tty);
1350         struct sk_buff *skb;
1351         int chr, flg;
1352         unsigned char *p;
1353
1354         if (ppp != 0)
1355                 CHECK_PPP_VOID();
1356         /*
1357          * This can happen if stuff comes in on the backup tty.
1358          */
1359         if (ppp == 0 || tty != ppp->tty)
1360                 return;
1361         /*
1362          * Verify the table pointer and ensure that the line is
1363          * still in PPP discipline.
1364          */
1365         if (ppp->magic != PPP_MAGIC) {
1366                 if (ppp->flags & SC_DEBUG)
1367                         printk(KERN_DEBUG
1368                                "PPP: tty_receive called but couldn't find "
1369                                "PPP struct.\n");
1370                 return;
1371         }
1372         /*
1373          * Print the buffer if desired
1374          */
1375         if (ppp->flags & SC_LOG_RAWIN)
1376                 ppp_print_buffer ("receive buffer", data, count);
1377
1378         ppp->stats.ppp_ibytes += count;
1379         skb = ppp->rpkt;
1380         
1381         if ( ppp->flags & SC_SYNC ) {
1382                 /* synchronous mode */
1383                 
1384                 if (ppp->toss==0xE0) {
1385                         /* this is the 1st frame, reset vj comp */
1386                         ppp_receive_error(ppp);
1387                         ppp->toss = 0;
1388                 }
1389                 
1390                 /*
1391                  * Allocate an skbuff for frame.
1392                  * The 128 is room for VJ header expansion.
1393                  */
1394                 
1395                 if (skb == NULL)
1396                         skb = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
1397                         
1398                 if (skb == NULL) {
1399                         if (ppp->flags & SC_DEBUG)
1400                                 printk(KERN_DEBUG "couldn't "
1401                                        "alloc skb for recv\n");
1402                 } else {
1403                         LIBERATE_SKB(skb);
1404                         /*
1405                          * Decompress A/C and protocol compression here.
1406                          */
1407                         p = skb_put(skb, 2);
1408                         p[0] = PPP_ALLSTATIONS;
1409                         p[1] = PPP_UI;
1410                         if (*data == PPP_ALLSTATIONS) {
1411                                 data += 2;
1412                                 count -= 2;
1413                         }
1414                         if ((*data & 1) != 0) {
1415                                 p = skb_put(skb, 1);
1416                                 p[0] = 0;
1417                         }
1418
1419                         /* copy frame to socket buffer */
1420                         p = skb_put(skb, count);
1421                         memcpy(p,data,count);
1422                         
1423                         /*
1424                          * Check if we've overflowed the MRU
1425                          */
1426                         if (skb->len >= ppp->mru + PPP_HDRLEN + 2
1427                             || skb_tailroom(skb) <= 0) {
1428                                 ++ppp->estats.rx_length_errors;
1429                                 if (ppp->flags & SC_DEBUG)
1430                                         printk(KERN_DEBUG "rcv frame too long: "
1431                                                "len=%d mru=%d hroom=%d troom=%d\n",
1432                                                skb->len, ppp->mru, skb_headroom(skb),
1433                                                skb_tailroom(skb));
1434                         } else {
1435                                 if (!ppp_receive_frame(ppp, skb)) {
1436                                         KFREE_SKB(skb);
1437                                         ppp_receive_error(ppp);
1438                                 }
1439                         }
1440                 
1441                         /* Reset for the next frame */
1442                         skb = NULL;
1443                 }
1444                 ppp->rpkt = skb;
1445                 return;
1446         }
1447         
1448         while (count-- > 0) {
1449                 /*
1450                  * Collect the character and error condition for the character.
1451                  * Set the toss flag for the first character error.
1452                  */
1453                 chr = *data++;
1454                 if (flags) {
1455                         flg = *flags++;
1456                         if (flg) {
1457                                 if (ppp->toss == 0)
1458                                         ppp->toss = flg;
1459                                 switch (flg) {
1460                                 case TTY_OVERRUN:
1461                                         ++ppp->estats.rx_fifo_errors;
1462                                         break;
1463                                 case TTY_FRAME:
1464                                 case TTY_BREAK:
1465                                         ++ppp->estats.rx_frame_errors;
1466                                         break;
1467                                 }
1468                                 continue;
1469                         }
1470                 }
1471
1472                 /*
1473                  * Set the flags for d7 being 0/1 and parity being
1474                  * even/odd so that the normal processing would have
1475                  * all flags set at the end of the session.  A
1476                  * missing flag bit indicates an error condition.
1477                  */
1478
1479 #ifdef CHECK_CHARACTERS
1480                 if (chr & 0x80)
1481                         ppp->flags |= SC_RCV_B7_1;
1482                 else
1483                         ppp->flags |= SC_RCV_B7_0;
1484
1485                 if (paritytab[chr >> 5] & (1 << (chr & 0x1F)))
1486                         ppp->flags |= SC_RCV_ODDP;
1487                 else
1488                         ppp->flags |= SC_RCV_EVNP;
1489 #endif
1490
1491                 if (chr == PPP_FLAG) {
1492                         /*
1493                          * FLAG. This is the end of the block. If the block
1494                          * ends with ESC FLAG, then the block is to be ignored.
1495                          */
1496                         if (ppp->escape)
1497                                 ppp->toss |= 0x80;
1498                         /*
1499                          * Process the frame if it was received correctly.
1500                          * If there was an error, let the VJ decompressor know.
1501                          * There are 4 cases here:
1502                          * skb != NULL, toss != 0: error in frame
1503                          * skb != NULL, toss == 0: frame ok
1504                          * skb == NULL, toss != 0: very first frame,
1505                          *      error on 1st char, or alloc_skb failed
1506                          * skb == NULL, toss == 0: empty frame (~~)
1507                          */
1508                         if (ppp->toss || !ppp_receive_frame(ppp, skb)) {
1509                                 if (ppp->toss && (ppp->flags & SC_DEBUG))
1510                                         printk(KERN_DEBUG
1511                                                "ppp: tossing frame (%x)\n",
1512                                                ppp->toss);
1513                                 if (skb != NULL)
1514                                         KFREE_SKB(skb);
1515                                 if (!(ppp->toss == 0xE0 || ppp->toss == 0x80))
1516                                         ++ppp->stats.ppp_ierrors;
1517                                 ppp_receive_error(ppp);
1518                         }
1519                         /*
1520                          * Reset for the next frame.
1521                          */
1522                         skb = NULL;
1523                         ppp->rfcs = PPP_INITFCS;
1524                         ppp->escape = 0;
1525                         ppp->toss = 0;
1526                         continue;
1527                 }
1528
1529                 /* If we're tossing, look no further. */
1530                 if (ppp->toss != 0)
1531                         continue;
1532
1533                 /* If this is a control char to be ignored, do so */
1534                 if (in_rmap(ppp, chr))
1535                         continue;
1536
1537                 /*
1538                  * Modify the next character if preceded by escape.
1539                  * The escape character (0x7d) could be an escaped
1540                  * 0x5d, if it follows an escape :-)
1541                  */
1542                 if (ppp->escape) {
1543                         chr ^= PPP_TRANS;
1544                         ppp->escape = 0;
1545                 } else if (chr == PPP_ESCAPE) {
1546                         ppp->escape = PPP_TRANS;
1547                         continue;
1548                 }
1549
1550                 /*
1551                  * Allocate an skbuff on the first character received.
1552                  * The 128 is room for VJ header expansion and FCS.
1553                  */
1554                 if (skb == NULL) {
1555                         skb = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
1556                         if (skb == NULL) {
1557                                 if (ppp->flags & SC_DEBUG)
1558                                         printk(KERN_DEBUG "couldn't "
1559                                                "alloc skb for recv\n");
1560                                 ppp->toss = 1;
1561                                 continue;
1562                         }
1563                         LIBERATE_SKB(skb);
1564                 }
1565
1566                 /*
1567                  * Decompress A/C and protocol compression here.
1568                  */
1569                 if (skb->len == 0 && chr != PPP_ALLSTATIONS) {
1570                         p = skb_put(skb, 2);
1571                         p[0] = PPP_ALLSTATIONS;
1572                         p[1] = PPP_UI;
1573                 }
1574                 if (skb->len == 2 && (chr & 1) != 0) {
1575                         p = skb_put(skb, 1);
1576                         p[0] = 0;
1577                 }
1578
1579                 /*
1580                  * Check if we've overflowed the MRU
1581                  */
1582                 if (skb->len >= ppp->mru + PPP_HDRLEN + 2
1583                     || skb_tailroom(skb) <= 0) {
1584                         ++ppp->estats.rx_length_errors;
1585                         ppp->toss = 0xC0;
1586                         if (ppp->flags & SC_DEBUG)
1587                                 printk(KERN_DEBUG "rcv frame too long: "
1588                                        "len=%d mru=%d hroom=%d troom=%d\n",
1589                                        skb->len, ppp->mru, skb_headroom(skb),
1590                                        skb_tailroom(skb));
1591                         continue;
1592                 }
1593
1594                 /*
1595                  * Store the character and update the FCS.
1596                  */
1597                 p = skb_put(skb, 1);
1598                 *p = chr;
1599                 ppp->rfcs = PPP_FCS(ppp->rfcs, chr);
1600         }
1601         ppp->rpkt = skb;
1602 }
1603
1604 /*************************************************************
1605  * PPP NETWORK INTERFACE SUPPORT
1606  *      The following code implements the PPP network
1607  *      interface device and handles those parts of
1608  *      the PPP processing which are independent of the
1609  *      type of hardware link being used, including
1610  *      VJ and packet compression.
1611  *************************************************************/
1612
1613 /*
1614  * Network device driver callback routines
1615  */
1616
1617 static int ppp_init_dev(struct device *dev);
1618 static int ppp_dev_open(struct device *);
1619 static int ppp_dev_ioctl(struct device *dev, struct ifreq *ifr, int cmd);
1620 static int ppp_dev_close(struct device *);
1621 static int ppp_dev_xmit(struct sk_buff *, struct device *);
1622 static struct net_device_stats *ppp_dev_stats (struct device *);
1623
1624 #if LINUX_VERSION_CODE < VERSION(2,1,15)
1625 static int ppp_dev_header(struct sk_buff *, struct device *, __u16,
1626                           void *, void *, unsigned int);
1627 static int ppp_dev_rebuild(void *eth, struct device *dev,
1628                            unsigned long raddr, struct sk_buff *skb);
1629 #endif
1630
1631 /*
1632  * Information for the protocol decoder
1633  */
1634
1635 typedef int (*pfn_proto)  (struct ppp *, struct sk_buff *);
1636
1637 typedef struct ppp_proto_struct {
1638         int             proto;
1639         pfn_proto       func;
1640 } ppp_proto_type;
1641
1642 static int rcv_proto_ip         (struct ppp *, struct sk_buff *);
1643 static int rcv_proto_ipv6       (struct ppp *, struct sk_buff *);
1644 static int rcv_proto_ipx        (struct ppp *, struct sk_buff *);
1645 static int rcv_proto_at         (struct ppp *, struct sk_buff *);
1646 static int rcv_proto_vjc_comp   (struct ppp *, struct sk_buff *);
1647 static int rcv_proto_vjc_uncomp (struct ppp *, struct sk_buff *);
1648 static int rcv_proto_ccp        (struct ppp *, struct sk_buff *);
1649 static int rcv_proto_unknown    (struct ppp *, struct sk_buff *);
1650
1651 static
1652 ppp_proto_type proto_list[] = {
1653         { PPP_IP,         rcv_proto_ip         },
1654         { PPP_IPV6,       rcv_proto_ipv6       },
1655         { PPP_IPX,        rcv_proto_ipx        },
1656         { PPP_AT,         rcv_proto_at         },
1657         { PPP_VJC_COMP,   rcv_proto_vjc_comp   },
1658         { PPP_VJC_UNCOMP, rcv_proto_vjc_uncomp },
1659         { PPP_CCP,        rcv_proto_ccp        },
1660         { 0,              rcv_proto_unknown    }  /* !!! MUST BE LAST !!! */
1661 };
1662
1663 /*
1664  * Called when the PPP network interface device is actually created.
1665  */
1666 static int
1667 ppp_init_dev (struct device *dev)
1668 {
1669         dev->hard_header_len  = PPP_HDRLEN;
1670 #if LINUX_VERSION_CODE < VERSION(2,1,15)
1671         dev->hard_header      = ppp_dev_header;
1672         dev->rebuild_header   = ppp_dev_rebuild;
1673 #endif
1674
1675         /* device INFO */
1676         dev->mtu              = PPP_MTU;
1677         dev->hard_start_xmit  = ppp_dev_xmit;
1678         dev->open             = ppp_dev_open;
1679         dev->stop             = ppp_dev_close;
1680         dev->get_stats        = ppp_dev_stats;
1681         dev->do_ioctl         = ppp_dev_ioctl;
1682         dev->addr_len         = 0;
1683         dev->tx_queue_len     = 10;
1684         dev->type             = ARPHRD_PPP;
1685
1686 #if LINUX_VERSION_CODE < VERSION(2,1,20)
1687         {
1688                 int    indx;
1689
1690                 for (indx = 0; indx < DEV_NUMBUFFS; indx++)
1691                         skb_queue_head_init (&dev->buffs[indx]);
1692         }
1693 #else
1694         dev_init_buffers(dev);
1695 #endif
1696
1697         dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
1698
1699         return 0;
1700 }
1701
1702 /*
1703  * Callback from the network layer when the device goes up.
1704  */
1705
1706 static int
1707 ppp_dev_open (struct device *dev)
1708 {
1709         struct ppp *ppp = dev2ppp(dev);
1710
1711         if (!ppp->inuse || ppp2tty(ppp) == NULL) {
1712                 printk(KERN_ERR "ppp: %s not active\n", dev->name);
1713                 return -ENXIO;
1714         }
1715
1716         MOD_INC_USE_COUNT;
1717
1718         return 0;
1719 }
1720
1721 /*
1722  * Callback from the network layer when the ppp device goes down.
1723  */
1724
1725 static int
1726 ppp_dev_close (struct device *dev)
1727 {
1728         struct ppp *ppp = dev2ppp (dev);
1729
1730         CHECK_PPP_MAGIC(ppp);
1731
1732         MOD_DEC_USE_COUNT;
1733
1734         return 0;
1735 }
1736
1737 static inline void
1738 get_vj_stats(struct vjstat *vj, struct slcompress *slc)
1739 {
1740         vj->vjs_packets    = slc->sls_o_compressed + slc->sls_o_uncompressed;
1741         vj->vjs_compressed = slc->sls_o_compressed;
1742         vj->vjs_searches   = slc->sls_o_searches;
1743         vj->vjs_misses     = slc->sls_o_misses;
1744         vj->vjs_errorin    = slc->sls_i_error;
1745         vj->vjs_tossed     = slc->sls_i_tossed;
1746         vj->vjs_uncompressedin = slc->sls_i_uncompressed;
1747         vj->vjs_compressedin   = slc->sls_i_compressed;
1748 }
1749
1750 /*
1751  * Callback from the network layer to process the sockioctl functions.
1752  */
1753 static int
1754 ppp_dev_ioctl (struct device *dev, struct ifreq *ifr, int cmd)
1755 {
1756         struct ppp *ppp = dev2ppp(dev);
1757         int nb;
1758         union {
1759                 struct ppp_stats stats;
1760                 struct ppp_comp_stats cstats;
1761                 char vers[32];
1762         } u;
1763
1764         CHECK_PPP_MAGIC(ppp);
1765
1766         memset(&u, 0, sizeof(u));
1767         switch (cmd) {
1768         case SIOCGPPPSTATS:
1769                 u.stats.p = ppp->stats;
1770                 if (ppp->slcomp != NULL)
1771                         get_vj_stats(&u.stats.vj, ppp->slcomp);
1772                 nb = sizeof(u.stats);
1773                 break;
1774
1775         case SIOCGPPPCSTATS:
1776                 if (ppp->sc_xc_state != NULL)
1777                         (*ppp->sc_xcomp->comp_stat)
1778                                 (ppp->sc_xc_state, &u.cstats.c);
1779                 if (ppp->sc_rc_state != NULL)
1780                         (*ppp->sc_rcomp->decomp_stat)
1781                                 (ppp->sc_rc_state, &u.cstats.d);
1782                 nb = sizeof(u.cstats);
1783                 break;
1784
1785         case SIOCGPPPVER:
1786                 strcpy(u.vers, szVersion);
1787                 nb = strlen(u.vers) + 1;
1788                 break;
1789
1790         default:
1791                 return -EINVAL;
1792         }
1793
1794         if (COPY_TO_USER((void *) ifr->ifr_ifru.ifru_data, &u, nb))
1795                 return -EFAULT;
1796         return 0;
1797 }
1798
1799 /*
1800  * Process the generic PPP ioctls, i.e. those which are not specific
1801  * to any particular type of hardware link.
1802  */
1803 static int
1804 ppp_ioctl(struct ppp *ppp, unsigned int param2, unsigned long param3)
1805 {
1806         register int temp_i = 0, oldflags;
1807         int error = -EFAULT;
1808         unsigned long flags;
1809         struct ppp_idle cur_ddinfo;
1810         struct npioctl npi;
1811
1812         CHECK_PPP(-ENXIO);
1813
1814         /*
1815          * The user must have an euid of root to do these requests.
1816          */
1817         if (!SUSER())
1818                 return -EPERM;
1819
1820         switch (param2) {
1821         case PPPIOCSMRU:
1822                 /*
1823                  * Set the MRU value
1824                  */
1825                 if (GET_USER(temp_i, (int *) param3))
1826                         break;
1827                 if (temp_i < PPP_MRU)
1828                         temp_i = PPP_MRU;
1829                 ppp->mru = temp_i;
1830                 if (ppp->flags & SC_DEBUG)
1831                         printk(KERN_INFO
1832                                "ppp_ioctl: set mru to %x\n", temp_i);
1833                 error = 0;
1834                 break;
1835
1836         case PPPIOCGFLAGS:
1837                 /*
1838                  * Fetch the current flags
1839                  */
1840                 temp_i = ppp->flags & SC_MASK;
1841 #ifndef CHECK_CHARACTERS /* Don't generate errors if we don't check chars. */
1842                 temp_i |= SC_RCV_B7_1 | SC_RCV_B7_0 |
1843                           SC_RCV_ODDP | SC_RCV_EVNP;
1844 #endif
1845                 if (PUT_USER(temp_i, (int *) param3))
1846                         break;
1847                 error = 0;
1848                 break;
1849
1850         case PPPIOCSFLAGS:
1851                 /*
1852                  * Set the flags for the various options
1853                  */
1854                 if (GET_USER(temp_i, (int *) param3))
1855                         break;
1856
1857                 if (ppp->flags & ~temp_i & SC_CCP_OPEN)
1858                         ppp_ccp_closed(ppp);
1859
1860                 save_flags(flags);
1861                 cli();
1862                 oldflags = ppp->flags;
1863                 temp_i = (temp_i & SC_MASK) | (oldflags & ~SC_MASK);
1864                 ppp->flags = temp_i;
1865                 restore_flags(flags);
1866
1867                 if ((oldflags | temp_i) & SC_DEBUG)
1868                         printk(KERN_INFO
1869                                "ppp_ioctl: set flags to %x\n", temp_i);
1870                 error = 0;
1871                 break;
1872
1873         case PPPIOCSCOMPRESS:
1874                 /*
1875                  * Set the compression mode
1876                  */
1877                 error = ppp_set_compression
1878                         (ppp, (struct ppp_option_data *) param3);
1879                 break;
1880
1881         case PPPIOCGUNIT:
1882                 /*
1883                  * Obtain the unit number for this device.
1884                  */
1885                 if (PUT_USER(ppp->line, (int *) param3))
1886                         break;
1887                 if (ppp->flags & SC_DEBUG)
1888                         printk(KERN_INFO
1889                                "ppp_ioctl: get unit: %d\n", ppp->line);
1890                 error = 0;
1891                 break;
1892
1893         case PPPIOCSDEBUG:
1894                 /*
1895                  * Set the debug level
1896                  */
1897                 if (GET_USER(temp_i, (int *) param3))
1898                         break;
1899                 temp_i = (temp_i & 0x1F) << 16;
1900
1901                 if ((ppp->flags | temp_i) & SC_DEBUG)
1902                         printk(KERN_INFO
1903                                "ppp_ioctl: set dbg flags to %x\n", temp_i);
1904
1905                 save_flags(flags);
1906                 cli();
1907                 ppp->flags = (ppp->flags & ~0x1F0000) | temp_i;
1908                 restore_flags(flags);
1909                 error = 0;
1910                 break;
1911
1912         case PPPIOCGDEBUG:
1913                 /*
1914                  * Get the debug level
1915                  */
1916                 temp_i = (ppp->flags >> 16) & 0x1F;
1917                 if (PUT_USER(temp_i, (int *) param3))
1918                         break;
1919                 error = 0;
1920                 break;
1921
1922         case PPPIOCGIDLE:
1923                 /*
1924                  * Get the times since the last send/receive frame operation
1925                  */
1926                 /* change absolute times to relative times. */
1927                 cur_ddinfo.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
1928                 cur_ddinfo.recv_idle = (jiffies - ppp->last_recv) / HZ;
1929                 if (COPY_TO_USER((void *) param3, &cur_ddinfo,
1930                                  sizeof (cur_ddinfo)))
1931                         break;
1932                 error = 0;
1933                 break;
1934
1935         case PPPIOCSMAXCID:
1936                 /*
1937                  * Set the maximum VJ header compression slot number.
1938                  */
1939                 if (GET_USER(temp_i, (int *) param3))
1940                         break;
1941                 error = -EINVAL;
1942                 if (temp_i < 2 || temp_i > 255)
1943                         break;
1944                 ++temp_i;
1945                 if (ppp->flags & SC_DEBUG)
1946                         printk(KERN_INFO "ppp_ioctl: set maxcid to %d\n",
1947                                temp_i);
1948                 if (ppp->slcomp != NULL)
1949                         slhc_free(ppp->slcomp);
1950                 ppp->slcomp = slhc_init(16, temp_i);
1951
1952                 error = -ENOMEM;
1953                 if (ppp->slcomp == NULL) {
1954                         printk(KERN_ERR "ppp: no memory for VJ compression\n");
1955                         break;
1956                 }
1957                 error = 0;
1958                 break;
1959
1960         case PPPIOCGNPMODE:
1961         case PPPIOCSNPMODE:
1962                 if (COPY_FROM_USER(&npi, (void *) param3, sizeof(npi)))
1963                         break;
1964
1965                 switch (npi.protocol) {
1966                 case PPP_IPV6:
1967                         npi.protocol = NP_IPV6;
1968                         break;
1969                 case PPP_IP:
1970                         npi.protocol = NP_IP;
1971                         break;
1972                 case PPP_IPX:
1973                         npi.protocol = NP_IPX;
1974                         break;
1975                 case PPP_AT:
1976                         npi.protocol = NP_AT;
1977                         break;
1978                 default:
1979                         if (ppp->flags & SC_DEBUG)
1980                                 printk(KERN_DEBUG "pppioc[gs]npmode: "
1981                                        "invalid proto %d\n", npi.protocol);
1982                         error = -EINVAL;
1983                         goto out;
1984                 }
1985
1986                 if (param2 == PPPIOCGNPMODE) {
1987                         npi.mode = ppp->sc_npmode[npi.protocol];
1988                         if (COPY_TO_USER((void *) param3, &npi, sizeof(npi)))
1989                                 break;
1990                 } else {
1991                         ppp->sc_npmode[npi.protocol] = npi.mode;
1992                         if (ppp->flags & SC_DEBUG)
1993                                 printk(KERN_DEBUG "ppp: set np %d to %d\n",
1994                                        npi.protocol, npi.mode);
1995                         mark_bh(NET_BH);
1996                 }
1997                 error = 0;
1998                 break;
1999
2000         default:
2001                 /*
2002                  *  All other ioctl() events will come here.
2003                  */
2004                 if (ppp->flags & SC_DEBUG)
2005                         printk(KERN_ERR
2006                                "ppp_ioctl: invalid ioctl: %x, addr %lx\n",
2007                                param2, param3);
2008
2009                 error = -ENOIOCTLCMD;
2010                 break;
2011         }
2012 out:
2013         return error;
2014 }
2015
2016 /*
2017  * Process the set-compression ioctl.
2018  */
2019 static int
2020 ppp_set_compression (struct ppp *ppp, struct ppp_option_data *odp)
2021 {
2022         struct compressor *cp;
2023         int error, nb;
2024         unsigned long flags;
2025         __u8 *ptr;
2026         __u8 ccp_option[CCP_MAX_OPTION_LENGTH];
2027         struct ppp_option_data data;
2028
2029         /*
2030          * Fetch the compression parameters
2031          */
2032         error = -EFAULT;
2033         if (COPY_FROM_USER(&data, odp, sizeof (data)))
2034                 goto out;
2035
2036         nb  = data.length;
2037         ptr = data.ptr;
2038         if ((unsigned) nb >= CCP_MAX_OPTION_LENGTH)
2039                 nb = CCP_MAX_OPTION_LENGTH;
2040
2041         if (COPY_FROM_USER(ccp_option, ptr, nb))
2042                 goto out;
2043
2044         error = -EINVAL;
2045         if (ccp_option[1] < 2)  /* preliminary check on the length byte */
2046                 goto out;
2047
2048         save_flags(flags);
2049         cli();
2050         ppp->flags &= ~(data.transmit? SC_COMP_RUN: SC_DECOMP_RUN);
2051         restore_flags(flags);
2052
2053         cp = find_compressor (ccp_option[0]);
2054 #if defined(CONFIG_KMOD) || defined(CONFIG_KERNELD)
2055         if (cp == NULL) {
2056                 char modname[32];
2057                 sprintf(modname, "ppp-compress-%d", ccp_option[0]);
2058                 request_module(modname);
2059                 cp = find_compressor(ccp_option[0]);
2060         }
2061 #endif /* CONFIG_KMOD */
2062
2063         if (cp == NULL) {
2064                 if (ppp->flags & SC_DEBUG)
2065                         printk(KERN_DEBUG
2066                                "%s: no compressor for [%x %x %x], %x\n",
2067                                ppp->name, ccp_option[0], ccp_option[1],
2068                                ccp_option[2], nb);
2069                 goto out;               /* compressor not loaded */
2070         }
2071
2072         /*
2073          * Found a handler for the protocol - try to allocate
2074          * a compressor or decompressor.
2075          */
2076         error = 0;
2077         if (data.transmit) {
2078                 if (ppp->sc_xc_state != NULL)
2079                         (*ppp->sc_xcomp->comp_free)(ppp->sc_xc_state);
2080                 ppp->sc_xc_state = NULL;
2081
2082                 ppp->sc_xcomp    = cp;
2083                 ppp->sc_xc_state = cp->comp_alloc(ccp_option, nb);
2084                 if (ppp->sc_xc_state == NULL) {
2085                         if (ppp->flags & SC_DEBUG)
2086                                 printk(KERN_DEBUG "%s: comp_alloc failed\n",
2087                                        ppp->name);
2088                         error = -ENOBUFS;
2089                 }
2090         } else {
2091                 if (ppp->sc_rc_state != NULL)
2092                         (*ppp->sc_rcomp->decomp_free)(ppp->sc_rc_state);
2093                 ppp->sc_rc_state = NULL;
2094
2095                 ppp->sc_rcomp    = cp;
2096                 ppp->sc_rc_state = cp->decomp_alloc(ccp_option, nb);
2097                 if (ppp->sc_rc_state == NULL) {
2098                         if (ppp->flags & SC_DEBUG)
2099                                 printk(KERN_DEBUG "%s: decomp_alloc failed\n",
2100                                        ppp->name);
2101                         error = -ENOBUFS;
2102                 }
2103         }
2104 out:
2105         return error;
2106 }
2107
2108 /*
2109  * Handle a CCP packet.
2110  *
2111  * The CCP packet is passed along to the pppd process just like any
2112  * other PPP frame. The difference is that some processing needs to be
2113  * immediate or the compressors will become confused on the peer.
2114  */
2115
2116 static void ppp_proto_ccp(struct ppp *ppp, __u8 *dp, int len, int rcvd)
2117 {
2118         int slen    = CCP_LENGTH(dp);
2119         __u8 *opt = dp   + CCP_HDRLEN;
2120         int opt_len = slen - CCP_HDRLEN;
2121         unsigned long flags;
2122
2123         if (slen > len)
2124                 return;
2125
2126         if (ppp->flags & SC_DEBUG)
2127                 printk(KERN_DEBUG "ppp_proto_ccp rcvd=%d code=%x flags=%x\n",
2128                        rcvd, CCP_CODE(dp), ppp->flags);
2129         save_flags(flags);
2130         switch (CCP_CODE(dp)) {
2131         case CCP_CONFREQ:
2132         case CCP_TERMREQ:
2133         case CCP_TERMACK:
2134                 /*
2135                  * CCP must be going down - disable compression
2136                  */
2137                 if (ppp->flags & SC_CCP_UP) {
2138                         cli();
2139                         ppp->flags &= ~(SC_CCP_UP   |
2140                                         SC_COMP_RUN |
2141                                         SC_DECOMP_RUN);
2142                 }
2143                 break;
2144
2145         case CCP_CONFACK:
2146                 if ((ppp->flags & SC_CCP_OPEN) == 0)
2147                         break;
2148                 if (ppp->flags & SC_CCP_UP)
2149                         break;
2150                 if (slen < (CCP_HDRLEN + CCP_OPT_MINLEN))
2151                         break;
2152                 if (slen < (CCP_OPT_LENGTH (opt) + CCP_HDRLEN))
2153                         break;
2154                 if (!rcvd) {
2155                         /*
2156                          * we're agreeing to send compressed packets.
2157                          */
2158                         if (ppp->sc_xc_state == NULL)
2159                                 break;
2160
2161                         if ((*ppp->sc_xcomp->comp_init)
2162                             (ppp->sc_xc_state,
2163                              opt, opt_len,
2164                              ppp->line, 0, ppp->flags & SC_DEBUG)) {
2165                                 if (ppp->flags & SC_DEBUG)
2166                                         printk(KERN_DEBUG "%s: comp running\n",
2167                                                ppp->name);
2168                                 cli();
2169                                 ppp->flags |= SC_COMP_RUN;
2170                         }
2171                         break;
2172                 }
2173
2174                 /*
2175                  * peer is agreeing to send compressed packets.
2176                  */
2177                 if (ppp->sc_rc_state == NULL)
2178                         break;
2179
2180                 if ((*ppp->sc_rcomp->decomp_init)
2181                     (ppp->sc_rc_state,
2182                      opt, opt_len,
2183                      ppp->line, 0, ppp->mru, ppp->flags & SC_DEBUG)) {
2184                         if (ppp->flags & SC_DEBUG)
2185                                 printk(KERN_DEBUG "%s: decomp running\n",
2186                                        ppp->name);
2187                         cli();
2188                         ppp->flags |= SC_DECOMP_RUN;
2189                         ppp->flags &= ~(SC_DC_ERROR | SC_DC_FERROR);
2190                 }
2191                 break;
2192
2193         case CCP_RESETACK:
2194                 /*
2195                  * CCP Reset-ack resets compressors and decompressors
2196                  * as it passes through.
2197                  */
2198                 if ((ppp->flags & SC_CCP_UP) == 0)
2199                         break;
2200
2201                 if (!rcvd) {
2202                         if (ppp->sc_xc_state && (ppp->flags & SC_COMP_RUN)) {
2203                                 (*ppp->sc_xcomp->comp_reset)(ppp->sc_xc_state);
2204                                 if (ppp->flags & SC_DEBUG)
2205                                         printk(KERN_DEBUG "%s: comp reset\n",
2206                                                ppp->name);
2207                         }
2208                 } else {
2209                         if (ppp->sc_rc_state && (ppp->flags & SC_DECOMP_RUN)) {
2210                               (*ppp->sc_rcomp->decomp_reset)(ppp->sc_rc_state);
2211                               if (ppp->flags & SC_DEBUG)
2212                                         printk(KERN_DEBUG "%s: decomp reset\n",
2213                                                ppp->name);
2214                               cli();
2215                               ppp->flags &= ~SC_DC_ERROR;
2216                         }
2217                 }
2218                 break;
2219         }
2220         restore_flags(flags);
2221 }
2222
2223 /*
2224  * CCP is down; free (de)compressor state if necessary.
2225  */
2226
2227 static void
2228 ppp_ccp_closed(struct ppp *ppp)
2229 {
2230         unsigned long flags;
2231
2232         save_flags(flags);
2233         cli();
2234         ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP | SC_COMP_RUN | SC_DECOMP_RUN);
2235         restore_flags(flags);
2236         if (ppp->flags & SC_DEBUG)
2237                 printk(KERN_DEBUG "%s: ccp closed\n", ppp->name);
2238         if (ppp->sc_xc_state) {
2239                 (*ppp->sc_xcomp->comp_free) (ppp->sc_xc_state);
2240                 ppp->sc_xc_state = NULL;
2241         }
2242
2243         if (ppp->sc_rc_state) {
2244                 (*ppp->sc_rcomp->decomp_free) (ppp->sc_rc_state);
2245                 ppp->sc_rc_state = NULL;
2246         }
2247 }
2248
2249 /*************************************************************
2250  * RECEIVE-SIDE ROUTINES
2251  *************************************************************/
2252
2253 /*
2254  * On entry, a received frame is in skb.
2255  * Check it and dispose as appropriate.
2256  */
2257 static int
2258 ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb)
2259 {
2260         __u8    *data;
2261         int     count;
2262         int     proto;
2263         int     new_count;
2264         struct sk_buff *new_skb;
2265         ppp_proto_type  *proto_ptr;
2266
2267         /*
2268          * An empty frame is ignored. This occurs if the FLAG sequence
2269          * precedes and follows each frame.
2270          */
2271         if (skb == NULL)
2272                 return 1;
2273         if (skb->len == 0) {
2274                 KFREE_SKB(skb);
2275                 return 1;
2276         }
2277         data = skb->data;
2278         count = skb->len;
2279
2280         /*
2281          * Generate an error if the frame is too small.
2282          */
2283         if (count < PPP_HDRLEN + 2) {
2284                 if (ppp->flags & SC_DEBUG)
2285                         printk(KERN_DEBUG
2286                                "ppp: got runt ppp frame, %d chars\n", count);
2287                 ++ppp->estats.rx_length_errors;
2288                 return 0;
2289         }
2290
2291         if ( !(ppp->flags & SC_SYNC) ) { 
2292                 /*
2293                  * Verify the FCS of the frame and discard the FCS characters
2294                  * from the end of the buffer.
2295                  */
2296                 if (ppp->rfcs != PPP_GOODFCS) {
2297                         if (ppp->flags & SC_DEBUG) {
2298                                 printk(KERN_DEBUG
2299                                        "ppp: frame with bad fcs, length = %d\n",
2300                                        count);
2301                                 ppp_print_buffer("bad frame", data, count);
2302                         }
2303                         ++ppp->estats.rx_crc_errors;
2304                         return 0;
2305                 }
2306                 count -= 2;             /* ignore the fcs characters */
2307                 skb_trim(skb, count);
2308         }
2309         
2310         /*
2311          * Process the active decompressor.
2312          */
2313         if (ppp->sc_rc_state != NULL &&
2314             (ppp->flags & SC_DECOMP_RUN) &&
2315             ((ppp->flags & (SC_DC_FERROR | SC_DC_ERROR)) == 0)) {
2316                 if (PPP_PROTOCOL(data) == PPP_COMP) {
2317                         /*
2318                          * If the frame is compressed then decompress it.
2319                          */
2320                         new_skb = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
2321                         if (new_skb == NULL) {
2322                                 printk(KERN_ERR "ppp_recv_frame: no memory\n");
2323                                 new_count = DECOMP_ERROR;
2324                         } else {
2325                                 LIBERATE_SKB(new_skb);
2326                                 new_count = (*ppp->sc_rcomp->decompress)
2327                                         (ppp->sc_rc_state, data, count,
2328                                          new_skb->data, ppp->mru + PPP_HDRLEN);
2329                         }
2330                         if (new_count > 0) {
2331                                 /* Frame was decompressed OK */
2332                                 KFREE_SKB(skb);
2333                                 skb = new_skb;
2334                                 count = new_count;
2335                                 data = skb_put(skb, count);
2336
2337                         } else {
2338                                 /*
2339                                  * On a decompression error, we pass the
2340                                  * compressed frame up to pppd as an
2341                                  * error indication.
2342                                  */
2343                                 if (ppp->flags & SC_DEBUG)
2344                                         printk(KERN_INFO "%s: decomp err %d\n",
2345                                                ppp->name, new_count);
2346                                 if (new_skb != 0)
2347                                         KFREE_SKB(new_skb);
2348                                 if (ppp->slcomp != 0)
2349                                         slhc_toss(ppp->slcomp);
2350                                 ++ppp->stats.ppp_ierrors;
2351                                 if (new_count == DECOMP_FATALERROR) {
2352                                         ppp->flags |= SC_DC_FERROR;
2353                                 } else {
2354                                         ppp->flags |= SC_DC_ERROR;
2355                                 }
2356                         }
2357
2358
2359                 } else {
2360                         /*
2361                          * The frame is not compressed. Pass it to the
2362                          * decompression code so it can update its
2363                          * dictionary if necessary.
2364                          */
2365                         (*ppp->sc_rcomp->incomp)(ppp->sc_rc_state,
2366                                                  data, count);
2367                 }
2368         }
2369         else if (PPP_PROTOCOL(data) == PPP_COMP && (ppp->flags & SC_DEBUG))
2370                 printk(KERN_INFO "%s: not decomp, rc_state=%p flags=%x\n",
2371                        ppp->name, ppp->sc_rc_state, ppp->flags);
2372
2373         /*
2374          * Count the frame and print it
2375          */
2376         ++ppp->stats.ppp_ipackets;
2377         ppp->stats.ppp_ioctects += count;
2378         if (ppp->flags & SC_LOG_INPKT)
2379                 ppp_print_buffer ("receive frame", data, count);
2380
2381         /*
2382          * Find the procedure to handle this protocol.
2383          * The last one is marked as protocol 0 which is the 'catch-all'
2384          * to feed it to the pppd daemon.
2385          */
2386         proto = PPP_PROTOCOL(data);
2387         proto_ptr = proto_list;
2388         while (proto_ptr->proto != 0 && proto_ptr->proto != proto)
2389                 ++proto_ptr;
2390
2391         /*
2392          * Update the appropriate statistic counter.
2393          */
2394         if (!(*proto_ptr->func)(ppp, skb)) {
2395                 KFREE_SKB(skb);
2396                 ++ppp->stats.ppp_discards;
2397         }
2398
2399         return 1;
2400 }
2401
2402 /*
2403  * An input error has been detected, so we need to inform
2404  * the VJ decompressor.
2405  */
2406 static void
2407 ppp_receive_error(struct ppp *ppp)
2408 {
2409         CHECK_PPP_VOID();
2410
2411         if (ppp->slcomp != 0)
2412                 slhc_toss(ppp->slcomp);
2413 }
2414
2415 /*
2416  * Put the input frame into the networking system for the indicated protocol
2417  */
2418 static int
2419 ppp_rcv_rx(struct ppp *ppp, __u16 proto, struct sk_buff *skb)
2420 {
2421
2422         /*
2423          * Fill in a few fields of the skb and give it to netif_rx().
2424          */
2425         skb->dev      = ppp2dev(ppp);   /* We are the device */
2426         skb->protocol = htons(proto);
2427         skb_pull(skb, PPP_HDRLEN);      /* pull off ppp header */
2428         skb->mac.raw   = skb->data;
2429         ppp->last_recv = jiffies;
2430         netif_rx (skb);
2431         return 1;
2432 }
2433
2434 /*
2435  * Process the receipt of an IP frame
2436  */
2437 static int
2438 rcv_proto_ip(struct ppp *ppp, struct sk_buff *skb)
2439 {
2440         CHECK_PPP(0);
2441         if ((ppp2dev(ppp)->flags & IFF_UP) && (skb->len > 0)
2442             && ppp->sc_npmode[NP_IP] == NPMODE_PASS)
2443                 return ppp_rcv_rx(ppp, ETH_P_IP, skb);
2444         return 0;
2445 }
2446
2447 /*
2448  * Process the receipt of an IPv6 frame
2449  */
2450 static int
2451 rcv_proto_ipv6(struct ppp *ppp, struct sk_buff *skb)
2452 {
2453         CHECK_PPP(0);
2454         if ((ppp2dev(ppp)->flags & IFF_UP) && (skb->len > 0)
2455             && ppp->sc_npmode[NP_IPV6] == NPMODE_PASS)
2456                 return ppp_rcv_rx(ppp, ETH_P_IPV6, skb);
2457         return 0;
2458 }
2459
2460 /*
2461  * Process the receipt of an IPX frame
2462  */
2463 static int
2464 rcv_proto_ipx(struct ppp *ppp, struct sk_buff *skb)
2465 {
2466         CHECK_PPP(0);
2467         if (((ppp2dev(ppp)->flags & IFF_UP) != 0) && (skb->len > 0)
2468             && ppp->sc_npmode[NP_IPX] == NPMODE_PASS)
2469                 return ppp_rcv_rx(ppp, ETH_P_IPX, skb);
2470         return 0;
2471 }
2472
2473 /*
2474  * Process the receipt of an Appletalk frame
2475  */
2476 static int
2477 rcv_proto_at(struct ppp *ppp, struct sk_buff *skb)
2478 {
2479         CHECK_PPP(0);
2480         if ((ppp2dev(ppp)->flags & IFF_UP) && (skb->len > 0)
2481             && ppp->sc_npmode[NP_AT] == NPMODE_PASS)
2482                 return ppp_rcv_rx(ppp, ETH_P_PPPTALK, skb);
2483         return 0;
2484 }
2485
2486 /*
2487  * Process the receipt of an VJ Compressed frame
2488  */
2489 static int
2490 rcv_proto_vjc_comp(struct ppp *ppp, struct sk_buff *skb)
2491 {
2492         int new_count;
2493
2494         CHECK_PPP(0);
2495         if ((ppp->flags & SC_REJ_COMP_TCP) || ppp->slcomp == NULL)
2496                 return 0;
2497         new_count = slhc_uncompress(ppp->slcomp, skb->data + PPP_HDRLEN,
2498                                     skb->len - PPP_HDRLEN);
2499         if (new_count <= 0) {
2500                 if (ppp->flags & SC_DEBUG)
2501                         printk(KERN_NOTICE
2502                                "ppp: error in VJ decompression\n");
2503                 return 0;
2504         }
2505         new_count += PPP_HDRLEN;
2506         if (new_count > skb->len)
2507                 skb_put(skb, new_count - skb->len);
2508         else
2509                 skb_trim(skb, new_count);
2510         return rcv_proto_ip(ppp, skb);
2511 }
2512
2513 /*
2514  * Process the receipt of an VJ Un-compressed frame
2515  */
2516 static int
2517 rcv_proto_vjc_uncomp(struct ppp *ppp, struct sk_buff *skb)
2518 {
2519         CHECK_PPP(0);
2520         if ((ppp->flags & SC_REJ_COMP_TCP) || ppp->slcomp == NULL)
2521                 return 0;
2522         if (slhc_remember(ppp->slcomp, skb->data + PPP_HDRLEN,
2523                           skb->len - PPP_HDRLEN) <= 0) {
2524                 if (ppp->flags & SC_DEBUG)
2525                         printk(KERN_NOTICE "ppp: error in VJ memorizing\n");
2526                 return 0;
2527         }
2528         return rcv_proto_ip(ppp, skb);
2529 }
2530
2531 static int
2532 rcv_proto_ccp(struct ppp *ppp, struct sk_buff *skb)
2533 {
2534         CHECK_PPP(0);
2535         ppp_proto_ccp (ppp, skb->data + PPP_HDRLEN, skb->len - PPP_HDRLEN, 1);
2536         return rcv_proto_unknown(ppp, skb);
2537 }
2538
2539 /*
2540  * Receive all unclassified protocols.
2541  */
2542 static int
2543 rcv_proto_unknown(struct ppp *ppp, struct sk_buff *skb)
2544 {
2545         CHECK_PPP(0);
2546
2547         /*
2548          * Limit queue length by dropping old frames.
2549          */
2550         skb_queue_tail(&ppp->rcv_q, skb);
2551         while (ppp->rcv_q.qlen > PPP_MAX_RCV_QLEN) {
2552                 struct sk_buff *skb = skb_dequeue(&ppp->rcv_q);
2553                 if (skb)
2554                         KFREE_SKB(skb);
2555         }
2556
2557         wake_up_interruptible (&ppp->read_wait);
2558         if (ppp->tty->fasync != NULL)
2559                 kill_fasync (ppp->tty->fasync, SIGIO);
2560
2561         return 1;
2562 }
2563
2564 /*************************************************************
2565  * TRANSMIT-SIDE ROUTINES
2566  *************************************************************/
2567
2568 /* local function to store a value into the LQR frame */
2569 extern inline __u8 * store_long (register __u8 *p, register int value) {
2570         *p++ = (__u8) (value >> 24);
2571         *p++ = (__u8) (value >> 16);
2572         *p++ = (__u8) (value >>  8);
2573         *p++ = (__u8) value;
2574         return p;
2575 }
2576
2577 /*
2578  * Compress and send an frame to the peer.
2579  * Should be called with xmit_busy == 1, having been set by the caller.
2580  * That is, we use xmit_busy as a lock to prevent reentry of this
2581  * procedure.
2582  */
2583 static void
2584 ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
2585 {
2586         int     proto;
2587         __u8    *data;
2588         int     count;
2589         __u8    *p;
2590         int     ret;
2591
2592         CHECK_PPP_VOID();
2593         data = skb->data;
2594         count = skb->len;
2595
2596         /* dump the buffer */
2597         if (ppp->flags & SC_LOG_OUTPKT)
2598                 ppp_print_buffer ("write frame", data, count);
2599
2600         /*
2601          * Handle various types of protocol-specific compression
2602          * and other processing, including:
2603          * - VJ TCP header compression
2604          * - updating LQR packets
2605          * - updating CCP state on CCP packets
2606          */
2607         proto = PPP_PROTOCOL(data);
2608         switch (proto) {
2609         case PPP_IP:
2610                 if ((ppp->flags & SC_COMP_TCP) && ppp->slcomp != NULL)
2611                         skb = ppp_vj_compress(ppp, skb);
2612                 break;
2613
2614         case PPP_LQR:
2615                 /*
2616                  * Update the LQR frame with the current MIB information.
2617                  * This way the information is accurate and up-to-date.
2618                  */
2619                 if (count < 48)
2620                         break;
2621                 p = data + 40;  /* Point to last two items. */
2622                 p = store_long(p, ppp->stats.ppp_opackets + 1);
2623                 p = store_long(p, ppp->stats.ppp_ooctects + count);
2624                 ++ppp->stats.ppp_olqrs;
2625                 break;
2626
2627         case PPP_CCP:
2628                 /*
2629                  * Outbound compression control frames
2630                  */
2631                 ppp_proto_ccp(ppp, data + PPP_HDRLEN, count - PPP_HDRLEN, 0);
2632                 break;
2633         }
2634         data = skb->data;
2635         count = skb->len;
2636
2637         /*
2638          * Compress the whole frame if possible.
2639          */
2640         if (((ppp->flags & SC_COMP_RUN) != 0)   &&
2641             (ppp->sc_xc_state != (void *) 0)    &&
2642             (proto != PPP_LCP)                  &&
2643             (proto != PPP_CCP)) {
2644                 struct sk_buff *new_skb;
2645                 int new_count;
2646
2647                 /* Allocate an skb for the compressed frame. */
2648                 new_skb = alloc_skb(ppp->mtu + PPP_HDRLEN, GFP_ATOMIC);
2649                 if (new_skb == NULL) {
2650                         printk(KERN_ERR "ppp_send_frame: no memory\n");
2651                         KFREE_SKB(skb);
2652                         ppp->xmit_busy = 0;
2653                         return;
2654                 }
2655                 LIBERATE_SKB(new_skb);
2656
2657                 /* Compress the frame. */
2658                 new_count = (*ppp->sc_xcomp->compress)
2659                         (ppp->sc_xc_state, data, new_skb->data,
2660                          count, ppp->mtu + PPP_HDRLEN);
2661
2662                 /* Did it compress? */
2663                 if (new_count > 0 && (ppp->flags & SC_CCP_UP)) {
2664                         skb_put(new_skb, new_count);
2665                         KFREE_SKB(skb);
2666                         skb = new_skb;
2667                 } else {
2668                         /*
2669                          * The frame could not be compressed, or it could not
2670                          * be sent in compressed form because CCP is down.
2671                          */
2672                         KFREE_SKB(new_skb);
2673                 }
2674         }
2675
2676         /*
2677          * Send the frame
2678          */
2679         if ( ppp->flags & SC_SYNC ) 
2680                 ret = ppp_sync_send(ppp, skb);
2681         else
2682                 ret = ppp_async_send(ppp, skb);
2683         if (ret > 0) {
2684                 /* we can release the lock */
2685                 ppp->xmit_busy = 0;
2686         } else if (ret < 0) {
2687                 /* can't happen, since the caller got the xmit_busy lock */
2688                 printk(KERN_ERR "ppp: ppp_async_send didn't accept pkt\n");
2689         }
2690 }
2691
2692 /*
2693  * Apply VJ TCP header compression to a packet.
2694  */
2695 static struct sk_buff *
2696 ppp_vj_compress(struct ppp *ppp, struct sk_buff *skb)
2697 {
2698         __u8 *orig_data, *data;
2699         struct sk_buff *new_skb;
2700         int len, proto;
2701
2702         new_skb = alloc_skb(skb->len, GFP_ATOMIC);
2703         if (new_skb == NULL) {
2704                 printk(KERN_ERR "ppp: no memory for vj compression\n");
2705                 return skb;
2706         }
2707         LIBERATE_SKB(new_skb);
2708
2709         orig_data = data = skb->data + PPP_HDRLEN;
2710         len = slhc_compress(ppp->slcomp, data, skb->len - PPP_HDRLEN,
2711                             new_skb->data + PPP_HDRLEN, &data,
2712                             (ppp->flags & SC_NO_TCP_CCID) == 0);
2713
2714         if (data == orig_data) {
2715                 /* Couldn't compress the data */
2716                 KFREE_SKB(new_skb);
2717                 return skb;
2718         }
2719
2720         /* The data has been changed */
2721         if (data[0] & SL_TYPE_COMPRESSED_TCP) {
2722                 proto = PPP_VJC_COMP;
2723                 data[0] ^= SL_TYPE_COMPRESSED_TCP;
2724         } else {
2725                 if (data[0] >= SL_TYPE_UNCOMPRESSED_TCP)
2726                         proto = PPP_VJC_UNCOMP;
2727                 else
2728                         proto = PPP_IP;
2729                 data[0] = orig_data[0];
2730         }
2731
2732         data = skb_put(new_skb, len + PPP_HDRLEN);
2733         data[0] = PPP_ALLSTATIONS;
2734         data[1] = PPP_UI;
2735         data[2] = 0;
2736         data[3] = proto;
2737
2738         KFREE_SKB(skb);
2739         return new_skb;
2740 }
2741
2742 static inline void
2743 ppp_send_frames(struct ppp *ppp)
2744 {
2745         struct sk_buff *skb;
2746
2747         while (!test_and_set_bit(0, &ppp->xmit_busy)) {
2748                 skb = skb_dequeue(&ppp->xmt_q);
2749                 if (skb == NULL) {
2750                         ppp->xmit_busy = 0;
2751                         break;
2752                 }
2753                 ppp_send_frame(ppp, skb);
2754         }
2755         if (!ppp->xmit_busy && ppp->dev.tbusy) {
2756                 ppp->dev.tbusy = 0;
2757                 mark_bh(NET_BH);
2758         }
2759 }
2760
2761 /*
2762  * Called from the hardware (tty) layer when it can accept
2763  * another packet.
2764  */
2765 static void
2766 ppp_output_wakeup(struct ppp *ppp)
2767 {
2768         CHECK_PPP_VOID();
2769
2770         if (!ppp->xmit_busy) {
2771                 printk(KERN_ERR "ppp_output_wakeup called but xmit_busy==0\n");
2772                 return;
2773         }
2774         ppp->xmit_busy = 0;
2775         ppp_send_frames(ppp);
2776 }
2777
2778 /*
2779  * Send a control frame (from pppd).
2780  */
2781 static void
2782 ppp_send_ctrl(struct ppp *ppp, struct sk_buff *skb)
2783 {
2784         CHECK_PPP_VOID();
2785
2786         /*
2787          * Put the packet on the queue, then send as many as we can.
2788          */
2789         skb_queue_tail(&ppp->xmt_q, skb);
2790         ppp_send_frames(ppp);
2791 }
2792
2793
2794 /*************************************************************
2795  * NETWORK OUTPUT
2796  *    This routine accepts requests from the network layer
2797  *    and attempts to deliver the packets.
2798  *************************************************************/
2799 /*
2800  * Send a frame to the peer.
2801  * Returns 1 iff the frame was not accepted.
2802  */
2803 static int
2804 ppp_dev_xmit(struct sk_buff *skb, struct device *dev)
2805 {
2806         struct ppp *ppp = dev2ppp(dev);
2807         struct tty_struct *tty = ppp2tty(ppp);
2808         enum NPmode npmode;
2809         int proto;
2810         unsigned char *hdr;
2811
2812         /* just a little sanity check. */
2813         if (skb == NULL)
2814                 return 0;
2815         if (skb->data == NULL) {
2816                 KFREE_SKB(skb);
2817                 return 0;
2818         }
2819
2820         /*
2821          * Avoid timing problem should tty hangup while data is
2822          * queued to be sent.
2823          */
2824         if (!ppp->inuse) {
2825                 KFREE_SKB(skb);
2826                 return 0;
2827         }
2828
2829         /*
2830          * Validate the tty interface
2831          */
2832         if (tty == NULL) {
2833                 if (ppp->flags & SC_DEBUG)
2834                         printk(KERN_ERR
2835                                "ppp_dev_xmit: %s not connected to a TTY!\n",
2836                                dev->name);
2837                 KFREE_SKB(skb);
2838                 return 0;
2839         }
2840
2841         /*
2842          * Work out the appropriate network-protocol mode for this packet.
2843          */
2844         npmode = NPMODE_PASS;   /* default */
2845         switch (ntohs(skb->protocol)) {
2846         case ETH_P_IP:
2847                 proto = PPP_IP;
2848                 npmode = ppp->sc_npmode[NP_IP];
2849                 break;
2850         case ETH_P_IPV6:
2851                 proto = PPP_IPV6;
2852                 npmode = ppp->sc_npmode[NP_IPV6];
2853                 break;
2854         case ETH_P_IPX:
2855                 proto = PPP_IPX;
2856                 npmode = ppp->sc_npmode[NP_IPX];
2857                 break;
2858         case ETH_P_PPPTALK:
2859         case ETH_P_ATALK:
2860                 proto = PPP_AT;
2861                 npmode = ppp->sc_npmode[NP_AT];
2862                 break;
2863         default:
2864                 if (ppp->flags & SC_DEBUG)
2865                         printk(KERN_INFO "%s: packet for unknown proto %x\n",
2866                                ppp->name, ntohs(skb->protocol));
2867                 KFREE_SKB(skb);
2868                 return 0;
2869         }
2870
2871         /*
2872          * Drop, accept or reject the packet depending on the mode.
2873          */
2874         switch (npmode) {
2875         case NPMODE_PASS:
2876                 break;
2877
2878         case NPMODE_QUEUE:
2879                 /*
2880                  * We may not send the packet now, so drop it.
2881                  * XXX It would be nice to be able to return it to the
2882                  * network system to be queued and retransmitted later.
2883                  */
2884                 if (ppp->flags & SC_DEBUG)
2885                         printk(KERN_DEBUG "%s: returning frame\n", ppp->name);
2886                 KFREE_SKB(skb);
2887                 return 0;
2888
2889         case NPMODE_ERROR:
2890         case NPMODE_DROP:
2891                 if (ppp->flags & SC_DEBUG)
2892                         printk(KERN_DEBUG
2893                                "ppp_dev_xmit: dropping (npmode = %d) on %s\n",
2894                                npmode, ppp->name);
2895                 KFREE_SKB(skb);
2896                 return 0;
2897         }
2898
2899         /*
2900          * The dev->tbusy field acts as a lock to allow only
2901          * one packet to be processed at a time.  If we can't
2902          * get the lock, try again later.
2903          * We deliberately queue as little as possible inside
2904          * the ppp driver in order to minimize the latency
2905          * for high-priority packets.
2906          */
2907         if (test_and_set_bit(0, &ppp->xmit_busy)) {
2908                 dev->tbusy = 1; /* can't take it now */
2909                 return 1;
2910         }
2911         dev->tbusy = 0;
2912
2913         /*
2914          * Put the 4-byte PPP header on the packet.
2915          * If there isn't room for it, we have to copy the packet.
2916          */
2917         if (skb_headroom(skb) < PPP_HDRLEN) {
2918                 struct sk_buff *new_skb;
2919
2920                 new_skb = alloc_skb(skb->len + PPP_HDRLEN, GFP_ATOMIC);
2921                 if (new_skb == NULL) {
2922                         printk(KERN_ERR "%s: skb hdr alloc failed\n",
2923                                ppp->name);
2924                         KFREE_SKB(skb);
2925                         ppp->xmit_busy = 0;
2926                         ppp_send_frames(ppp);
2927                         return 0;
2928                 }
2929                 LIBERATE_SKB(new_skb);
2930                 skb_reserve(new_skb, PPP_HDRLEN);
2931                 memcpy(skb_put(new_skb, skb->len), skb->data, skb->len);
2932                 KFREE_SKB(skb);
2933                 skb = new_skb;
2934         }
2935
2936         hdr = skb_push(skb, PPP_HDRLEN);
2937         hdr[0] = PPP_ALLSTATIONS;
2938         hdr[1] = PPP_UI;
2939         hdr[2] = proto >> 8;
2940         hdr[3] = proto;
2941
2942         ppp_send_frame(ppp, skb);
2943         if (!ppp->xmit_busy)
2944                 ppp_send_frames(ppp);
2945         return 0;
2946 }
2947
2948 #if LINUX_VERSION_CODE < VERSION(2,1,15)
2949 /*
2950  * Null hard_header and header_rebuild routines.
2951  */
2952 static int ppp_dev_header(struct sk_buff *skb, struct device *dev,
2953                           unsigned short type, void *daddr,
2954                           void *saddr, unsigned int len)
2955 {
2956         return 0;
2957 }
2958
2959 static int ppp_dev_rebuild(void *eth, struct device *dev,
2960                            unsigned long raddr, struct sk_buff *skb)
2961 {
2962         return 0;
2963 }
2964 #endif /* < 2.1.15 */
2965
2966 /*
2967  * Generate the statistic information for the /proc/net/dev listing.
2968  */
2969 static struct net_device_stats *
2970 ppp_dev_stats (struct device *dev)
2971 {
2972         struct ppp *ppp = dev2ppp (dev);
2973
2974         ppp->estats.rx_packets = ppp->stats.ppp_ipackets;
2975         ppp->estats.rx_errors  = ppp->stats.ppp_ierrors;
2976         ppp->estats.tx_packets = ppp->stats.ppp_opackets;
2977         ppp->estats.tx_errors  = ppp->stats.ppp_oerrors;
2978 #if LINUX_VERSION_CODE >= VERSION(2,1,25)
2979         ppp->estats.rx_bytes   = ppp->stats.ppp_ibytes;
2980         ppp->estats.tx_bytes   = ppp->stats.ppp_obytes;
2981 #endif
2982
2983         return &ppp->estats;
2984 }
2985
2986 /*************************************************************
2987  * UTILITIES
2988  *    Miscellany called by various functions above.
2989  *************************************************************/
2990
2991 /* Locate the previous instance of the PPP channel */
2992 static struct ppp *
2993 ppp_find(int pid_value)
2994 {
2995         struct ppp      *ppp;
2996
2997         /* try to find the device which this pid is already using */
2998         for (ppp = ppp_list; ppp != 0; ppp = ppp->next) {
2999                 if (ppp->inuse && ppp->sc_xfer == pid_value) {
3000                         ppp->sc_xfer = 0;
3001                         break;
3002                 }
3003         }
3004         return ppp;
3005 }
3006
3007 /* allocate or create a PPP channel */
3008 static struct ppp *
3009 ppp_alloc(void)
3010 {
3011         int             if_num;
3012         int             status;
3013         struct device   *dev;
3014         struct ppp      *ppp;
3015
3016         /* try to find an free device */
3017         for (ppp = ppp_list; ppp != 0; ppp = ppp->next) {
3018                 if (!test_and_set_bit(0, &ppp->inuse)) {
3019                         dev = ppp2dev(ppp);
3020                         if (dev->flags & IFF_UP) {
3021                                 clear_bit(0, &ppp->inuse);
3022                                 continue;
3023                         }
3024                         /* Reregister device */
3025                         unregister_netdev(dev);
3026                         if (register_netdev(dev) == 0)
3027                                 return ppp;
3028                         printk(KERN_DEBUG "could not reregister ppp device\n");
3029                         /* leave inuse set in this case */
3030                 }
3031         }
3032
3033         /*
3034          * There are no available units, so make a new one.
3035          */
3036         ppp = (struct ppp *) kmalloc(sizeof(struct ppp), GFP_KERNEL);
3037         if (ppp == 0) {
3038                 printk(KERN_ERR "ppp: struct ppp allocation failed\n");
3039                 return 0;
3040         }
3041         memset(ppp, 0, sizeof(*ppp));
3042
3043         /* initialize channel control data */
3044         ppp->magic = PPP_MAGIC;
3045         ppp->next = NULL;
3046         ppp->inuse = 1;
3047         ppp->read_wait = NULL;
3048
3049         /*
3050          * Make up a suitable name for this device
3051          */
3052         dev = ppp2dev(ppp);
3053         dev->name = ppp->name;
3054 #if LINUX_VERSION_CODE < VERSION(2,1,31)
3055         if_num = (ppp_list == 0)? 0: ppp_last->line + 1;
3056         sprintf(ppp->name, "ppp%d", if_num);
3057 #else
3058         if_num = dev_alloc_name(dev, "ppp%d");
3059 #endif
3060         if (if_num < 0) {
3061                 printk(KERN_ERR "ppp: dev_alloc_name failed (%d)\n", if_num);
3062                 kfree(ppp);
3063                 return 0;
3064         }
3065         ppp->line = if_num;
3066         ppp->slcomp = NULL;
3067
3068         dev->next = NULL;
3069         dev->init = ppp_init_dev;
3070         dev->name = ppp->name;
3071         dev->priv = (void *) ppp;
3072
3073         /* register device so that we can be ifconfig'd */
3074         /* ppp_init_dev() will be called as a side-effect */
3075         status = register_netdev (dev);
3076         if (status == 0) {
3077                 printk(KERN_INFO "registered device %s\n", dev->name);
3078         } else {
3079                 printk(KERN_ERR
3080                        "ppp_alloc - register_netdev(%s) = %d failure.\n",
3081                        dev->name, status);
3082                 kfree(ppp);
3083                 ppp = NULL;
3084         }
3085
3086         /* link this unit into our list */
3087         if (ppp_list == 0)
3088                 ppp_list = ppp;
3089         else
3090                 ppp_last->next = ppp;
3091         ppp_last = ppp;
3092
3093         return ppp;
3094 }
3095
3096 /*
3097  * Initialize the generic parts of the ppp structure.
3098  */
3099 static void
3100 ppp_generic_init(struct ppp *ppp)
3101 {
3102         int indx;
3103
3104         ppp->flags  = 0;
3105         ppp->mtu    = PPP_MTU;
3106         ppp->mru    = PPP_MRU;
3107
3108         skb_queue_head_init(&ppp->xmt_q);
3109         skb_queue_head_init(&ppp->rcv_q);
3110
3111         ppp->last_xmit  = jiffies;
3112         ppp->last_recv  = jiffies;
3113         ppp->xmit_busy  = 0;
3114
3115         /* clear statistics */
3116         memset(&ppp->stats, 0, sizeof (struct pppstat));
3117         memset(&ppp->estats, 0, sizeof(struct net_device_stats));
3118
3119         /* PPP compression data */
3120         ppp->sc_xc_state = NULL;
3121         ppp->sc_rc_state = NULL;
3122
3123         for (indx = 0; indx < NUM_NP; ++indx)
3124                 ppp->sc_npmode[indx] = NPMODE_PASS;
3125 }
3126
3127 /*
3128  * Called to clean up the generic parts of the ppp structure.
3129  */
3130 static void
3131 ppp_release(struct ppp *ppp)
3132 {
3133         struct sk_buff *skb;
3134
3135         CHECK_PPP_MAGIC(ppp);
3136
3137         if (ppp->flags & SC_DEBUG)
3138                 printk(KERN_DEBUG "%s released\n", ppp->name);
3139
3140         ppp_ccp_closed(ppp);
3141
3142         /* Ensure that the pppd process is not hanging on select()/poll() */
3143         wake_up_interruptible(&ppp->read_wait);
3144
3145         if (ppp->slcomp) {
3146                 slhc_free(ppp->slcomp);
3147                 ppp->slcomp = NULL;
3148         }
3149
3150         while ((skb = skb_dequeue(&ppp->rcv_q)) != NULL)
3151                 KFREE_SKB(skb);
3152         while ((skb = skb_dequeue(&ppp->xmt_q)) != NULL)
3153                 KFREE_SKB(skb);
3154
3155         ppp->inuse = 0;
3156         if (ppp->dev.tbusy) {
3157                 ppp->dev.tbusy = 0;
3158                 mark_bh(NET_BH);
3159         }
3160 }
3161
3162 /*
3163  * Utility procedures to print a buffer in hex/ascii
3164  */
3165 static void
3166 ppp_print_hex (register __u8 * out, const __u8 * in, int count)
3167 {
3168         register __u8 next_ch;
3169         static char hex[] = "0123456789ABCDEF";
3170
3171         while (count-- > 0) {
3172                 next_ch = *in++;
3173                 *out++ = hex[(next_ch >> 4) & 0x0F];
3174                 *out++ = hex[next_ch & 0x0F];
3175                 ++out;
3176         }
3177 }
3178
3179 static void
3180 ppp_print_char (register __u8 * out, const __u8 * in, int count)
3181 {
3182         register __u8 next_ch;
3183
3184         while (count-- > 0) {
3185                 next_ch = *in++;
3186
3187                 if (next_ch < 0x20 || next_ch > 0x7e)
3188                         *out++ = '.';
3189                 else {
3190                         *out++ = next_ch;
3191                         if (next_ch == '%')   /* printk/syslogd has a bug !! */
3192                                 *out++ = '%';
3193                 }
3194         }
3195         *out = '\0';
3196 }
3197
3198 static void
3199 ppp_print_buffer (const char *name, const __u8 *buf, int count)
3200 {
3201         __u8 line[44];
3202
3203         if (name != NULL)
3204                 printk(KERN_DEBUG "ppp: %s, count = %d\n", name, count);
3205
3206         while (count > 8) {
3207                 memset (line, 32, 44);
3208                 ppp_print_hex (line, buf, 8);
3209                 ppp_print_char (&line[8 * 3], buf, 8);
3210                 printk(KERN_DEBUG "%s\n", line);
3211                 count -= 8;
3212                 buf += 8;
3213         }
3214
3215         if (count > 0) {
3216                 memset (line, 32, 44);
3217                 ppp_print_hex (line, buf, count);
3218                 ppp_print_char (&line[8 * 3], buf, count);
3219                 printk(KERN_DEBUG "%s\n", line);
3220         }
3221 }
3222
3223 /*************************************************************
3224  * Compressor module interface
3225  *************************************************************/
3226
3227 struct compressor_link {
3228         struct compressor_link  *next;
3229         struct compressor       *comp;
3230 };
3231
3232 static struct compressor_link *ppp_compressors = (struct compressor_link *) 0;
3233
3234 static struct compressor *find_compressor (int type)
3235 {
3236         struct compressor_link *lnk;
3237         unsigned long flags;
3238
3239         save_flags(flags);
3240         cli();
3241
3242         lnk = ppp_compressors;
3243         while (lnk != (struct compressor_link *) 0) {
3244                 if ((int) (__u8) lnk->comp->compress_proto == type) {
3245                         restore_flags(flags);
3246                         return lnk->comp;
3247                 }
3248                 lnk = lnk->next;
3249         }
3250
3251         restore_flags(flags);
3252         return (struct compressor *) 0;
3253 }
3254
3255 static int ppp_register_compressor (struct compressor *cp)
3256 {
3257         struct compressor_link *new;
3258         unsigned long flags;
3259
3260         new = (struct compressor_link *)
3261                 kmalloc (sizeof (struct compressor_link), GFP_KERNEL);
3262
3263         if (new == (struct compressor_link *) 0)
3264                 return 1;
3265
3266         save_flags(flags);
3267         cli();
3268
3269         if (find_compressor (cp->compress_proto)) {
3270                 restore_flags(flags);
3271                 kfree (new);
3272                 return 0;
3273         }
3274
3275         new->next       = ppp_compressors;
3276         new->comp       = cp;
3277         ppp_compressors = new;
3278
3279         restore_flags(flags);
3280         return 0;
3281 }
3282
3283 static void ppp_unregister_compressor (struct compressor *cp)
3284 {
3285         struct compressor_link *prev = (struct compressor_link *) 0;
3286         struct compressor_link *lnk;
3287         unsigned long flags;
3288
3289         save_flags(flags);
3290         cli();
3291
3292         lnk  = ppp_compressors;
3293         while (lnk != (struct compressor_link *) 0) {
3294                 if (lnk->comp == cp) {
3295                         if (prev)
3296                                 prev->next = lnk->next;
3297                         else
3298                                 ppp_compressors = lnk->next;
3299                         kfree (lnk);
3300                         break;
3301                 }
3302                 prev = lnk;
3303                 lnk  = lnk->next;
3304         }
3305         restore_flags(flags);
3306 }
3307
3308 /*************************************************************
3309  * Module support routines
3310  *************************************************************/
3311
3312 #ifdef MODULE
3313 int
3314 init_module(void)
3315 {
3316         int status;
3317
3318         /* register our line disciplines */
3319         status = ppp_first_time();
3320         if (status != 0)
3321                 printk(KERN_INFO "PPP: ppp_init() failure %d\n", status);
3322 #if LINUX_VERSION_CODE < VERSION(2,1,18)
3323         else
3324                 (void) register_symtab (&ppp_syms);
3325 #endif
3326
3327         return status;
3328 }
3329
3330 void
3331 cleanup_module(void)
3332 {
3333         int status;
3334         struct ppp *ppp, *next_ppp;
3335         int busy = 0;
3336
3337         /*
3338          * Ensure that the devices are not in operation.
3339          */
3340         for (ppp = ppp_list; ppp != 0; ppp = ppp->next) {
3341                 CHECK_PPP_MAGIC(ppp);
3342                 if (ppp->inuse || (ppp->dev.flags & IFF_UP))
3343                         ++busy;
3344         }
3345         if (busy)
3346                 printk(KERN_CRIT "PPP: removing despite %d units in use!\n",
3347                        busy);
3348
3349         /*
3350          * Release the tty registration of the line discipline so that
3351          * ttys can no longer be put into PPP line discipline.
3352          */
3353         status = tty_register_ldisc (N_PPP, NULL);
3354         if (status != 0)
3355                 printk(KERN_ERR
3356                        "PPP: Unable to unregister ppp line discipline "
3357                        "(err = %d)\n", status);
3358         else
3359                 printk(KERN_INFO
3360                        "PPP: ppp line discipline successfully unregistered\n");
3361
3362         /*
3363          * De-register the devices so that there is no problem with them
3364          */
3365         for (ppp = ppp_list; ppp != 0; ppp = next_ppp) {
3366                 next_ppp = ppp->next;
3367                 unregister_netdev(&ppp->dev);
3368                 kfree (ppp);
3369         }
3370 }
3371 #endif