blob: c6fbb1ede0ed23e66dbd6a1941a145689622cef6 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Routines to compress and uncompress tcp packets (for transmission
3 * over low speed serial lines).
4 *
5 * Copyright (c) 1989 Regents of the University of California.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms are permitted
9 * provided that the above copyright notice and this paragraph are
10 * duplicated in all such forms and that any documentation,
11 * advertising materials, and other materials related to such
12 * distribution and use acknowledge that the software was developed
13 * by the University of California, Berkeley. The name of the
14 * University may not be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
19 *
20 * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
21 * - Initial distribution.
22 *
23 *
24 * modified for KA9Q Internet Software Package by
25 * Katie Stevens (dkstevens@ucdavis.edu)
26 * University of California, Davis
27 * Computing Services
28 * - 01-31-90 initial adaptation (from 1.19)
29 * PPP.05 02-15-90 [ks]
30 * PPP.08 05-02-90 [ks] use PPP protocol field to signal compression
31 * PPP.15 09-90 [ks] improve mbuf handling
32 * PPP.16 11-02 [karn] substantially rewritten to use NOS facilities
33 *
34 * - Feb 1991 Bill_Simpson@um.cc.umich.edu
35 * variable number of conversation slots
36 * allow zero or one slots
37 * separate routines
38 * status display
39 * - Jul 1994 Dmitry Gorodchanin
40 * Fixes for memory leaks.
41 * - Oct 1994 Dmitry Gorodchanin
42 * Modularization.
43 * - Jan 1995 Bjorn Ekwall
44 * Use ip_fast_csum from ip.h
45 * - July 1995 Christos A. Polyzols
46 * Spotted bug in tcp option checking
47 *
48 *
49 * This module is a difficult issue. It's clearly inet code but it's also clearly
50 * driver code belonging close to PPP and SLIP
51 */
52
53#include <linux/config.h>
54#include <linux/module.h>
55#include <linux/types.h>
56#include <linux/string.h>
57#include <linux/errno.h>
58#include <linux/kernel.h>
59#include <net/slhc_vj.h>
60
61#ifdef CONFIG_INET
62/* Entire module is for IP only */
63#include <linux/mm.h>
64#include <linux/socket.h>
65#include <linux/sockios.h>
66#include <linux/termios.h>
67#include <linux/in.h>
68#include <linux/fcntl.h>
69#include <linux/inet.h>
70#include <linux/netdevice.h>
71#include <net/ip.h>
72#include <net/protocol.h>
73#include <net/icmp.h>
74#include <net/tcp.h>
75#include <linux/skbuff.h>
76#include <net/sock.h>
77#include <linux/timer.h>
78#include <asm/system.h>
79#include <asm/uaccess.h>
80#include <net/checksum.h>
81#include <asm/unaligned.h>
82
83static unsigned char *encode(unsigned char *cp, unsigned short n);
84static long decode(unsigned char **cpp);
85static unsigned char * put16(unsigned char *cp, unsigned short x);
86static unsigned short pull16(unsigned char **cpp);
87
88/* Initialize compression data structure
89 * slots must be in range 0 to 255 (zero meaning no compression)
90 */
91struct slcompress *
92slhc_init(int rslots, int tslots)
93{
94 register short i;
95 register struct cstate *ts;
96 struct slcompress *comp;
97
98 comp = (struct slcompress *)kmalloc(sizeof(struct slcompress),
99 GFP_KERNEL);
100 if (! comp)
101 goto out_fail;
102 memset(comp, 0, sizeof(struct slcompress));
103
104 if ( rslots > 0 && rslots < 256 ) {
105 size_t rsize = rslots * sizeof(struct cstate);
106 comp->rstate = (struct cstate *) kmalloc(rsize, GFP_KERNEL);
107 if (! comp->rstate)
108 goto out_free;
109 memset(comp->rstate, 0, rsize);
110 comp->rslot_limit = rslots - 1;
111 }
112
113 if ( tslots > 0 && tslots < 256 ) {
114 size_t tsize = tslots * sizeof(struct cstate);
115 comp->tstate = (struct cstate *) kmalloc(tsize, GFP_KERNEL);
116 if (! comp->tstate)
117 goto out_free2;
118 memset(comp->tstate, 0, tsize);
119 comp->tslot_limit = tslots - 1;
120 }
121
122 comp->xmit_oldest = 0;
123 comp->xmit_current = 255;
124 comp->recv_current = 255;
125 /*
126 * don't accept any packets with implicit index until we get
127 * one with an explicit index. Otherwise the uncompress code
128 * will try to use connection 255, which is almost certainly
129 * out of range
130 */
131 comp->flags |= SLF_TOSS;
132
133 if ( tslots > 0 ) {
134 ts = comp->tstate;
135 for(i = comp->tslot_limit; i > 0; --i){
136 ts[i].cs_this = i;
137 ts[i].next = &(ts[i - 1]);
138 }
139 ts[0].next = &(ts[comp->tslot_limit]);
140 ts[0].cs_this = 0;
141 }
142 return comp;
143
144out_free2:
145 kfree((unsigned char *)comp->rstate);
146out_free:
147 kfree((unsigned char *)comp);
148out_fail:
149 return NULL;
150}
151
152
153/* Free a compression data structure */
154void
155slhc_free(struct slcompress *comp)
156{
157 if ( comp == NULLSLCOMPR )
158 return;
159
160 if ( comp->tstate != NULLSLSTATE )
161 kfree( comp->tstate );
162
163 if ( comp->rstate != NULLSLSTATE )
164 kfree( comp->rstate );
165
166 kfree( comp );
167}
168
169
170/* Put a short in host order into a char array in network order */
171static inline unsigned char *
172put16(unsigned char *cp, unsigned short x)
173{
174 *cp++ = x >> 8;
175 *cp++ = x;
176
177 return cp;
178}
179
180
181/* Encode a number */
182unsigned char *
183encode(unsigned char *cp, unsigned short n)
184{
185 if(n >= 256 || n == 0){
186 *cp++ = 0;
187 cp = put16(cp,n);
188 } else {
189 *cp++ = n;
190 }
191 return cp;
192}
193
194/* Pull a 16-bit integer in host order from buffer in network byte order */
195static unsigned short
196pull16(unsigned char **cpp)
197{
198 short rval;
199
200 rval = *(*cpp)++;
201 rval <<= 8;
202 rval |= *(*cpp)++;
203 return rval;
204}
205
206/* Decode a number */
207long
208decode(unsigned char **cpp)
209{
210 register int x;
211
212 x = *(*cpp)++;
213 if(x == 0){
214 return pull16(cpp) & 0xffff; /* pull16 returns -1 on error */
215 } else {
216 return x & 0xff; /* -1 if PULLCHAR returned error */
217 }
218}
219
220/*
221 * icp and isize are the original packet.
222 * ocp is a place to put a copy if necessary.
223 * cpp is initially a pointer to icp. If the copy is used,
224 * change it to ocp.
225 */
226
227int
228slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
229 unsigned char *ocp, unsigned char **cpp, int compress_cid)
230{
231 register struct cstate *ocs = &(comp->tstate[comp->xmit_oldest]);
232 register struct cstate *lcs = ocs;
233 register struct cstate *cs = lcs->next;
234 register unsigned long deltaS, deltaA;
235 register short changes = 0;
236 int hlen;
237 unsigned char new_seq[16];
238 register unsigned char *cp = new_seq;
239 struct iphdr *ip;
240 struct tcphdr *th, *oth;
241
242
243 /*
244 * Don't play with runt packets.
245 */
246
247 if(isize<sizeof(struct iphdr))
248 return isize;
249
250 ip = (struct iphdr *) icp;
251
252 /* Bail if this packet isn't TCP, or is an IP fragment */
253 if (ip->protocol != IPPROTO_TCP || (ntohs(ip->frag_off) & 0x3fff)) {
254 /* Send as regular IP */
255 if(ip->protocol != IPPROTO_TCP)
256 comp->sls_o_nontcp++;
257 else
258 comp->sls_o_tcp++;
259 return isize;
260 }
261 /* Extract TCP header */
262
263 th = (struct tcphdr *)(((unsigned char *)ip) + ip->ihl*4);
264 hlen = ip->ihl*4 + th->doff*4;
265
266 /* Bail if the TCP packet isn't `compressible' (i.e., ACK isn't set or
267 * some other control bit is set). Also uncompressible if
268 * it's a runt.
269 */
270 if(hlen > isize || th->syn || th->fin || th->rst ||
271 ! (th->ack)){
272 /* TCP connection stuff; send as regular IP */
273 comp->sls_o_tcp++;
274 return isize;
275 }
276 /*
277 * Packet is compressible -- we're going to send either a
278 * COMPRESSED_TCP or UNCOMPRESSED_TCP packet. Either way,
279 * we need to locate (or create) the connection state.
280 *
281 * States are kept in a circularly linked list with
282 * xmit_oldest pointing to the end of the list. The
283 * list is kept in lru order by moving a state to the
284 * head of the list whenever it is referenced. Since
285 * the list is short and, empirically, the connection
286 * we want is almost always near the front, we locate
287 * states via linear search. If we don't find a state
288 * for the datagram, the oldest state is (re-)used.
289 */
290 for ( ; ; ) {
291 if( ip->saddr == cs->cs_ip.saddr
292 && ip->daddr == cs->cs_ip.daddr
293 && th->source == cs->cs_tcp.source
294 && th->dest == cs->cs_tcp.dest)
295 goto found;
296
297 /* if current equal oldest, at end of list */
298 if ( cs == ocs )
299 break;
300 lcs = cs;
301 cs = cs->next;
302 comp->sls_o_searches++;
303 };
304 /*
305 * Didn't find it -- re-use oldest cstate. Send an
306 * uncompressed packet that tells the other side what
307 * connection number we're using for this conversation.
308 *
309 * Note that since the state list is circular, the oldest
310 * state points to the newest and we only need to set
311 * xmit_oldest to update the lru linkage.
312 */
313 comp->sls_o_misses++;
314 comp->xmit_oldest = lcs->cs_this;
315 goto uncompressed;
316
317found:
318 /*
319 * Found it -- move to the front on the connection list.
320 */
321 if(lcs == ocs) {
322 /* found at most recently used */
323 } else if (cs == ocs) {
324 /* found at least recently used */
325 comp->xmit_oldest = lcs->cs_this;
326 } else {
327 /* more than 2 elements */
328 lcs->next = cs->next;
329 cs->next = ocs->next;
330 ocs->next = cs;
331 }
332
333 /*
334 * Make sure that only what we expect to change changed.
335 * Check the following:
336 * IP protocol version, header length & type of service.
337 * The "Don't fragment" bit.
338 * The time-to-live field.
339 * The TCP header length.
340 * IP options, if any.
341 * TCP options, if any.
342 * If any of these things are different between the previous &
343 * current datagram, we send the current datagram `uncompressed'.
344 */
345 oth = &cs->cs_tcp;
346
347 if(ip->version != cs->cs_ip.version || ip->ihl != cs->cs_ip.ihl
348 || ip->tos != cs->cs_ip.tos
349 || (ip->frag_off & htons(0x4000)) != (cs->cs_ip.frag_off & htons(0x4000))
350 || ip->ttl != cs->cs_ip.ttl
351 || th->doff != cs->cs_tcp.doff
352 || (ip->ihl > 5 && memcmp(ip+1,cs->cs_ipopt,((ip->ihl)-5)*4) != 0)
353 || (th->doff > 5 && memcmp(th+1,cs->cs_tcpopt,((th->doff)-5)*4) != 0)){
354 goto uncompressed;
355 }
356
357 /*
358 * Figure out which of the changing fields changed. The
359 * receiver expects changes in the order: urgent, window,
360 * ack, seq (the order minimizes the number of temporaries
361 * needed in this section of code).
362 */
363 if(th->urg){
364 deltaS = ntohs(th->urg_ptr);
365 cp = encode(cp,deltaS);
366 changes |= NEW_U;
367 } else if(th->urg_ptr != oth->urg_ptr){
368 /* argh! URG not set but urp changed -- a sensible
369 * implementation should never do this but RFC793
370 * doesn't prohibit the change so we have to deal
371 * with it. */
372 goto uncompressed;
373 }
374 if((deltaS = ntohs(th->window) - ntohs(oth->window)) != 0){
375 cp = encode(cp,deltaS);
376 changes |= NEW_W;
377 }
378 if((deltaA = ntohl(th->ack_seq) - ntohl(oth->ack_seq)) != 0L){
379 if(deltaA > 0x0000ffff)
380 goto uncompressed;
381 cp = encode(cp,deltaA);
382 changes |= NEW_A;
383 }
384 if((deltaS = ntohl(th->seq) - ntohl(oth->seq)) != 0L){
385 if(deltaS > 0x0000ffff)
386 goto uncompressed;
387 cp = encode(cp,deltaS);
388 changes |= NEW_S;
389 }
390
391 switch(changes){
392 case 0: /* Nothing changed. If this packet contains data and the
393 * last one didn't, this is probably a data packet following
394 * an ack (normal on an interactive connection) and we send
395 * it compressed. Otherwise it's probably a retransmit,
396 * retransmitted ack or window probe. Send it uncompressed
397 * in case the other side missed the compressed version.
398 */
399 if(ip->tot_len != cs->cs_ip.tot_len &&
400 ntohs(cs->cs_ip.tot_len) == hlen)
401 break;
402 goto uncompressed;
403 break;
404 case SPECIAL_I:
405 case SPECIAL_D:
406 /* actual changes match one of our special case encodings --
407 * send packet uncompressed.
408 */
409 goto uncompressed;
410 case NEW_S|NEW_A:
411 if(deltaS == deltaA &&
412 deltaS == ntohs(cs->cs_ip.tot_len) - hlen){
413 /* special case for echoed terminal traffic */
414 changes = SPECIAL_I;
415 cp = new_seq;
416 }
417 break;
418 case NEW_S:
419 if(deltaS == ntohs(cs->cs_ip.tot_len) - hlen){
420 /* special case for data xfer */
421 changes = SPECIAL_D;
422 cp = new_seq;
423 }
424 break;
425 }
426 deltaS = ntohs(ip->id) - ntohs(cs->cs_ip.id);
427 if(deltaS != 1){
428 cp = encode(cp,deltaS);
429 changes |= NEW_I;
430 }
431 if(th->psh)
432 changes |= TCP_PUSH_BIT;
433 /* Grab the cksum before we overwrite it below. Then update our
434 * state with this packet's header.
435 */
436 deltaA = ntohs(th->check);
437 memcpy(&cs->cs_ip,ip,20);
438 memcpy(&cs->cs_tcp,th,20);
439 /* We want to use the original packet as our compressed packet.
440 * (cp - new_seq) is the number of bytes we need for compressed
441 * sequence numbers. In addition we need one byte for the change
442 * mask, one for the connection id and two for the tcp checksum.
443 * So, (cp - new_seq) + 4 bytes of header are needed.
444 */
445 deltaS = cp - new_seq;
446 if(compress_cid == 0 || comp->xmit_current != cs->cs_this){
447 cp = ocp;
448 *cpp = ocp;
449 *cp++ = changes | NEW_C;
450 *cp++ = cs->cs_this;
451 comp->xmit_current = cs->cs_this;
452 } else {
453 cp = ocp;
454 *cpp = ocp;
455 *cp++ = changes;
456 }
457 cp = put16(cp,(short)deltaA); /* Write TCP checksum */
458/* deltaS is now the size of the change section of the compressed header */
459 memcpy(cp,new_seq,deltaS); /* Write list of deltas */
460 memcpy(cp+deltaS,icp+hlen,isize-hlen);
461 comp->sls_o_compressed++;
462 ocp[0] |= SL_TYPE_COMPRESSED_TCP;
463 return isize - hlen + deltaS + (cp - ocp);
464
465 /* Update connection state cs & send uncompressed packet (i.e.,
466 * a regular ip/tcp packet but with the 'conversation id' we hope
467 * to use on future compressed packets in the protocol field).
468 */
469uncompressed:
470 memcpy(&cs->cs_ip,ip,20);
471 memcpy(&cs->cs_tcp,th,20);
472 if (ip->ihl > 5)
473 memcpy(cs->cs_ipopt, ip+1, ((ip->ihl) - 5) * 4);
474 if (th->doff > 5)
475 memcpy(cs->cs_tcpopt, th+1, ((th->doff) - 5) * 4);
476 comp->xmit_current = cs->cs_this;
477 comp->sls_o_uncompressed++;
478 memcpy(ocp, icp, isize);
479 *cpp = ocp;
480 ocp[9] = cs->cs_this;
481 ocp[0] |= SL_TYPE_UNCOMPRESSED_TCP;
482 return isize;
483}
484
485
486int
487slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize)
488{
489 register int changes;
490 long x;
491 register struct tcphdr *thp;
492 register struct iphdr *ip;
493 register struct cstate *cs;
494 int len, hdrlen;
495 unsigned char *cp = icp;
496
497 /* We've got a compressed packet; read the change byte */
498 comp->sls_i_compressed++;
499 if(isize < 3){
500 comp->sls_i_error++;
501 return 0;
502 }
503 changes = *cp++;
504 if(changes & NEW_C){
505 /* Make sure the state index is in range, then grab the state.
506 * If we have a good state index, clear the 'discard' flag.
507 */
508 x = *cp++; /* Read conn index */
509 if(x < 0 || x > comp->rslot_limit)
510 goto bad;
511
512 comp->flags &=~ SLF_TOSS;
513 comp->recv_current = x;
514 } else {
515 /* this packet has an implicit state index. If we've
516 * had a line error since the last time we got an
517 * explicit state index, we have to toss the packet. */
518 if(comp->flags & SLF_TOSS){
519 comp->sls_i_tossed++;
520 return 0;
521 }
522 }
523 cs = &comp->rstate[comp->recv_current];
524 thp = &cs->cs_tcp;
525 ip = &cs->cs_ip;
526
527 if((x = pull16(&cp)) == -1) { /* Read the TCP checksum */
528 goto bad;
529 }
530 thp->check = htons(x);
531
532 thp->psh = (changes & TCP_PUSH_BIT) ? 1 : 0;
533/*
534 * we can use the same number for the length of the saved header and
535 * the current one, because the packet wouldn't have been sent
536 * as compressed unless the options were the same as the previous one
537 */
538
539 hdrlen = ip->ihl * 4 + thp->doff * 4;
540
541 switch(changes & SPECIALS_MASK){
542 case SPECIAL_I: /* Echoed terminal traffic */
543 {
544 register short i;
545 i = ntohs(ip->tot_len) - hdrlen;
546 thp->ack_seq = htonl( ntohl(thp->ack_seq) + i);
547 thp->seq = htonl( ntohl(thp->seq) + i);
548 }
549 break;
550
551 case SPECIAL_D: /* Unidirectional data */
552 thp->seq = htonl( ntohl(thp->seq) +
553 ntohs(ip->tot_len) - hdrlen);
554 break;
555
556 default:
557 if(changes & NEW_U){
558 thp->urg = 1;
559 if((x = decode(&cp)) == -1) {
560 goto bad;
561 }
562 thp->urg_ptr = htons(x);
563 } else
564 thp->urg = 0;
565 if(changes & NEW_W){
566 if((x = decode(&cp)) == -1) {
567 goto bad;
568 }
569 thp->window = htons( ntohs(thp->window) + x);
570 }
571 if(changes & NEW_A){
572 if((x = decode(&cp)) == -1) {
573 goto bad;
574 }
575 thp->ack_seq = htonl( ntohl(thp->ack_seq) + x);
576 }
577 if(changes & NEW_S){
578 if((x = decode(&cp)) == -1) {
579 goto bad;
580 }
581 thp->seq = htonl( ntohl(thp->seq) + x);
582 }
583 break;
584 }
585 if(changes & NEW_I){
586 if((x = decode(&cp)) == -1) {
587 goto bad;
588 }
589 ip->id = htons (ntohs (ip->id) + x);
590 } else
591 ip->id = htons (ntohs (ip->id) + 1);
592
593 /*
594 * At this point, cp points to the first byte of data in the
595 * packet. Put the reconstructed TCP and IP headers back on the
596 * packet. Recalculate IP checksum (but not TCP checksum).
597 */
598
599 len = isize - (cp - icp);
600 if (len < 0)
601 goto bad;
602 len += hdrlen;
603 ip->tot_len = htons(len);
604 ip->check = 0;
605
606 memmove(icp + hdrlen, cp, len - hdrlen);
607
608 cp = icp;
609 memcpy(cp, ip, 20);
610 cp += 20;
611
612 if (ip->ihl > 5) {
613 memcpy(cp, cs->cs_ipopt, (ip->ihl - 5) * 4);
614 cp += (ip->ihl - 5) * 4;
615 }
616
617 put_unaligned(ip_fast_csum(icp, ip->ihl),
618 &((struct iphdr *)icp)->check);
619
620 memcpy(cp, thp, 20);
621 cp += 20;
622
623 if (thp->doff > 5) {
624 memcpy(cp, cs->cs_tcpopt, ((thp->doff) - 5) * 4);
625 cp += ((thp->doff) - 5) * 4;
626 }
627
628 return len;
629bad:
630 comp->sls_i_error++;
631 return slhc_toss( comp );
632}
633
634
635int
636slhc_remember(struct slcompress *comp, unsigned char *icp, int isize)
637{
638 register struct cstate *cs;
639 unsigned ihl;
640
641 unsigned char index;
642
643 if(isize < 20) {
644 /* The packet is shorter than a legal IP header */
645 comp->sls_i_runt++;
646 return slhc_toss( comp );
647 }
648 /* Peek at the IP header's IHL field to find its length */
649 ihl = icp[0] & 0xf;
650 if(ihl < 20 / 4){
651 /* The IP header length field is too small */
652 comp->sls_i_runt++;
653 return slhc_toss( comp );
654 }
655 index = icp[9];
656 icp[9] = IPPROTO_TCP;
657
658 if (ip_fast_csum(icp, ihl)) {
659 /* Bad IP header checksum; discard */
660 comp->sls_i_badcheck++;
661 return slhc_toss( comp );
662 }
663 if(index > comp->rslot_limit) {
664 comp->sls_i_error++;
665 return slhc_toss(comp);
666 }
667
668 /* Update local state */
669 cs = &comp->rstate[comp->recv_current = index];
670 comp->flags &=~ SLF_TOSS;
671 memcpy(&cs->cs_ip,icp,20);
672 memcpy(&cs->cs_tcp,icp + ihl*4,20);
673 if (ihl > 5)
674 memcpy(cs->cs_ipopt, icp + sizeof(struct iphdr), (ihl - 5) * 4);
675 if (cs->cs_tcp.doff > 5)
676 memcpy(cs->cs_tcpopt, icp + ihl*4 + sizeof(struct tcphdr), (cs->cs_tcp.doff - 5) * 4);
677 cs->cs_hsize = ihl*2 + cs->cs_tcp.doff*2;
678 /* Put headers back on packet
679 * Neither header checksum is recalculated
680 */
681 comp->sls_i_uncompressed++;
682 return isize;
683}
684
685int
686slhc_toss(struct slcompress *comp)
687{
688 if ( comp == NULLSLCOMPR )
689 return 0;
690
691 comp->flags |= SLF_TOSS;
692 return 0;
693}
694
695
696/* VJ header compression */
697EXPORT_SYMBOL(slhc_init);
698EXPORT_SYMBOL(slhc_free);
699EXPORT_SYMBOL(slhc_remember);
700EXPORT_SYMBOL(slhc_compress);
701EXPORT_SYMBOL(slhc_uncompress);
702EXPORT_SYMBOL(slhc_toss);
703
704#ifdef MODULE
705
706int init_module(void)
707{
708 printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California\n");
709 return 0;
710}
711
712void cleanup_module(void)
713{
714 return;
715}
716
717#endif /* MODULE */
718#else /* CONFIG_INET */
719
720
721int
722slhc_toss(struct slcompress *comp)
723{
724 printk(KERN_DEBUG "Called IP function on non IP-system: slhc_toss");
725 return -EINVAL;
726}
727int
728slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize)
729{
730 printk(KERN_DEBUG "Called IP function on non IP-system: slhc_uncompress");
731 return -EINVAL;
732}
733int
734slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
735 unsigned char *ocp, unsigned char **cpp, int compress_cid)
736{
737 printk(KERN_DEBUG "Called IP function on non IP-system: slhc_compress");
738 return -EINVAL;
739}
740
741int
742slhc_remember(struct slcompress *comp, unsigned char *icp, int isize)
743{
744 printk(KERN_DEBUG "Called IP function on non IP-system: slhc_remember");
745 return -EINVAL;
746}
747
748void
749slhc_free(struct slcompress *comp)
750{
751 printk(KERN_DEBUG "Called IP function on non IP-system: slhc_free");
752 return;
753}
754struct slcompress *
755slhc_init(int rslots, int tslots)
756{
757 printk(KERN_DEBUG "Called IP function on non IP-system: slhc_init");
758 return NULL;
759}
760EXPORT_SYMBOL(slhc_init);
761EXPORT_SYMBOL(slhc_free);
762EXPORT_SYMBOL(slhc_remember);
763EXPORT_SYMBOL(slhc_compress);
764EXPORT_SYMBOL(slhc_uncompress);
765EXPORT_SYMBOL(slhc_toss);
766
767#endif /* CONFIG_INET */
768MODULE_LICENSE("Dual BSD/GPL");