1/*
  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/module.h>
 54#include <linux/slab.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 <linux/uaccess.h>
 79#include <net/checksum.h>
 80#include <linux/unaligned.h>
 81
 82static unsigned char *encode(unsigned char *cp, unsigned short n);
 83static long decode(unsigned char **cpp);
 84static unsigned char * put16(unsigned char *cp, unsigned short x);
 85static unsigned short pull16(unsigned char **cpp);
 86
 87/* Allocate compression data structure
 88 *	slots must be in range 0 to 255 (zero meaning no compression)
 89 * Returns pointer to structure or ERR_PTR() on error.
 90 */
 91struct slcompress *
 92slhc_init(int rslots, int tslots)
 93{
 94	short i;
 95	struct cstate *ts;
 96	struct slcompress *comp;
 97
 98	if (rslots < 0 || rslots > 255 || tslots < 0 || tslots > 255)
 99		return ERR_PTR(-EINVAL);
100
101	comp = kzalloc(sizeof(struct slcompress), GFP_KERNEL);
102	if (! comp)
103		goto out_fail;
104
105	if (rslots > 0) {
106		size_t rsize = rslots * sizeof(struct cstate);
107		comp->rstate = kzalloc(rsize, GFP_KERNEL);
108		if (! comp->rstate)
109			goto out_free;
110		comp->rslot_limit = rslots - 1;
111	}
112
113	if (tslots > 0) {
114		size_t tsize = tslots * sizeof(struct cstate);
115		comp->tstate = kzalloc(tsize, GFP_KERNEL);
116		if (! comp->tstate)
117			goto out_free2;
118		comp->tslot_limit = tslots - 1;
119	}
120
121	comp->xmit_oldest = 0;
122	comp->xmit_current = 255;
123	comp->recv_current = 255;
124	/*
125	 * don't accept any packets with implicit index until we get
126	 * one with an explicit index.  Otherwise the uncompress code
127	 * will try to use connection 255, which is almost certainly
128	 * out of range
129	 */
130	comp->flags |= SLF_TOSS;
131
132	if ( tslots > 0 ) {
133		ts = comp->tstate;
134		for(i = comp->tslot_limit; i > 0; --i){
135			ts[i].cs_this = i;
136			ts[i].next = &(ts[i - 1]);
137		}
138		ts[0].next = &(ts[comp->tslot_limit]);
139		ts[0].cs_this = 0;
140	}
141	return comp;
142
143out_free2:
144	kfree(comp->rstate);
145out_free:
146	kfree(comp);
147out_fail:
148	return ERR_PTR(-ENOMEM);
149}
150
151
152/* Free a compression data structure */
153void
154slhc_free(struct slcompress *comp)
155{
156	if ( IS_ERR_OR_NULL(comp) )
157		return;
158
159	if ( comp->tstate != NULLSLSTATE )
160		kfree( comp->tstate );
161
162	if ( comp->rstate != NULLSLSTATE )
163		kfree( comp->rstate );
164
165	kfree( comp );
166}
167
168
169/* Put a short in host order into a char array in network order */
170static inline unsigned char *
171put16(unsigned char *cp, unsigned short x)
172{
173	*cp++ = x >> 8;
174	*cp++ = x;
175
176	return cp;
177}
178
179
180/* Encode a number */
181static unsigned char *
182encode(unsigned char *cp, unsigned short n)
183{
184	if(n >= 256 || n == 0){
185		*cp++ = 0;
186		cp = put16(cp,n);
187	} else {
188		*cp++ = n;
189	}
190	return cp;
191}
192
193/* Pull a 16-bit integer in host order from buffer in network byte order */
194static unsigned short
195pull16(unsigned char **cpp)
196{
197	short rval;
198
199	rval = *(*cpp)++;
200	rval <<= 8;
201	rval |= *(*cpp)++;
202	return rval;
203}
204
205/* Decode a number */
206static long
207decode(unsigned char **cpp)
208{
209	int x;
210
211	x = *(*cpp)++;
212	if(x == 0){
213		return pull16(cpp) & 0xffff;	/* pull16 returns -1 on error */
214	} else {
215		return x & 0xff;		/* -1 if PULLCHAR returned error */
216	}
217}
218
219/*
220 * icp and isize are the original packet.
221 * ocp is a place to put a copy if necessary.
222 * cpp is initially a pointer to icp.  If the copy is used,
223 *    change it to ocp.
224 */
225
226int
227slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
228	unsigned char *ocp, unsigned char **cpp, int compress_cid)
229{
230	struct cstate *ocs = &(comp->tstate[comp->xmit_oldest]);
231	struct cstate *lcs = ocs;
232	struct cstate *cs = lcs->next;
233	unsigned long deltaS, deltaA;
234	short changes = 0;
235	int nlen, hlen;
236	unsigned char new_seq[16];
237	unsigned char *cp = new_seq;
238	struct iphdr *ip;
239	struct tcphdr *th, *oth;
240	__sum16 csum;
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	if (ip->version != 4 || ip->ihl < 5)
252		return isize;
253
254	/* Bail if this packet isn't TCP, or is an IP fragment */
255	if (ip->protocol != IPPROTO_TCP || (ntohs(ip->frag_off) & 0x3fff)) {
256		/* Send as regular IP */
257		if(ip->protocol != IPPROTO_TCP)
258			comp->sls_o_nontcp++;
259		else
260			comp->sls_o_tcp++;
261		return isize;
262	}
263	nlen = ip->ihl * 4;
264	if (isize < nlen + sizeof(*th))
265		return isize;
266
267	th = (struct tcphdr *)(icp + nlen);
268	if (th->doff < sizeof(struct tcphdr) / 4)
269		return isize;
270	hlen = nlen + th->doff * 4;
271
272	/*  Bail if the TCP packet isn't `compressible' (i.e., ACK isn't set or
273	 *  some other control bit is set). Also uncompressible if
274	 *  it's a runt.
275	 */
276	if(hlen > isize || th->syn || th->fin || th->rst ||
277	    ! (th->ack)){
278		/* TCP connection stuff; send as regular IP */
279		comp->sls_o_tcp++;
280		return isize;
281	}
282	/*
283	 * Packet is compressible -- we're going to send either a
284	 * COMPRESSED_TCP or UNCOMPRESSED_TCP packet.  Either way,
285	 * we need to locate (or create) the connection state.
286	 *
287	 * States are kept in a circularly linked list with
288	 * xmit_oldest pointing to the end of the list.  The
289	 * list is kept in lru order by moving a state to the
290	 * head of the list whenever it is referenced.  Since
291	 * the list is short and, empirically, the connection
292	 * we want is almost always near the front, we locate
293	 * states via linear search.  If we don't find a state
294	 * for the datagram, the oldest state is (re-)used.
295	 */
296	for ( ; ; ) {
297		if( ip->saddr == cs->cs_ip.saddr
298		 && ip->daddr == cs->cs_ip.daddr
299		 && th->source == cs->cs_tcp.source
300		 && th->dest == cs->cs_tcp.dest)
301			goto found;
302
303		/* if current equal oldest, at end of list */
304		if ( cs == ocs )
305			break;
306		lcs = cs;
307		cs = cs->next;
308		comp->sls_o_searches++;
309	}
310	/*
311	 * Didn't find it -- re-use oldest cstate.  Send an
312	 * uncompressed packet that tells the other side what
313	 * connection number we're using for this conversation.
314	 *
315	 * Note that since the state list is circular, the oldest
316	 * state points to the newest and we only need to set
317	 * xmit_oldest to update the lru linkage.
318	 */
319	comp->sls_o_misses++;
320	comp->xmit_oldest = lcs->cs_this;
321	goto uncompressed;
322
323found:
324	/*
325	 * Found it -- move to the front on the connection list.
326	 */
327	if(lcs == ocs) {
328		/* found at most recently used */
329	} else if (cs == ocs) {
330		/* found at least recently used */
331		comp->xmit_oldest = lcs->cs_this;
332	} else {
333		/* more than 2 elements */
334		lcs->next = cs->next;
335		cs->next = ocs->next;
336		ocs->next = cs;
337	}
338
339	/*
340	 * Make sure that only what we expect to change changed.
341	 * Check the following:
342	 * IP protocol version, header length & type of service.
343	 * The "Don't fragment" bit.
344	 * The time-to-live field.
345	 * The TCP header length.
346	 * IP options, if any.
347	 * TCP options, if any.
348	 * If any of these things are different between the previous &
349	 * current datagram, we send the current datagram `uncompressed'.
350	 */
351	oth = &cs->cs_tcp;
352
353	if(ip->version != cs->cs_ip.version || ip->ihl != cs->cs_ip.ihl
354	 || ip->tos != cs->cs_ip.tos
355	 || (ip->frag_off & htons(0x4000)) != (cs->cs_ip.frag_off & htons(0x4000))
356	 || ip->ttl != cs->cs_ip.ttl
357	 || th->doff != cs->cs_tcp.doff
358	 || (ip->ihl > 5 && memcmp(ip+1,cs->cs_ipopt,((ip->ihl)-5)*4) != 0)
359	 || (th->doff > 5 && memcmp(th+1,cs->cs_tcpopt,((th->doff)-5)*4) != 0)){
360		goto uncompressed;
361	}
362
363	/*
364	 * Figure out which of the changing fields changed.  The
365	 * receiver expects changes in the order: urgent, window,
366	 * ack, seq (the order minimizes the number of temporaries
367	 * needed in this section of code).
368	 */
369	if(th->urg){
370		deltaS = ntohs(th->urg_ptr);
371		cp = encode(cp,deltaS);
372		changes |= NEW_U;
373	} else if(th->urg_ptr != oth->urg_ptr){
374		/* argh! URG not set but urp changed -- a sensible
375		 * implementation should never do this but RFC793
376		 * doesn't prohibit the change so we have to deal
377		 * with it. */
378		goto uncompressed;
379	}
380	if((deltaS = ntohs(th->window) - ntohs(oth->window)) != 0){
381		cp = encode(cp,deltaS);
382		changes |= NEW_W;
383	}
384	if((deltaA = ntohl(th->ack_seq) - ntohl(oth->ack_seq)) != 0L){
385		if(deltaA > 0x0000ffff)
386			goto uncompressed;
387		cp = encode(cp,deltaA);
388		changes |= NEW_A;
389	}
390	if((deltaS = ntohl(th->seq) - ntohl(oth->seq)) != 0L){
391		if(deltaS > 0x0000ffff)
392			goto uncompressed;
393		cp = encode(cp,deltaS);
394		changes |= NEW_S;
395	}
396
397	switch(changes){
398	case 0:	/* Nothing changed. If this packet contains data and the
399		 * last one didn't, this is probably a data packet following
400		 * an ack (normal on an interactive connection) and we send
401		 * it compressed.  Otherwise it's probably a retransmit,
402		 * retransmitted ack or window probe.  Send it uncompressed
403		 * in case the other side missed the compressed version.
404		 */
405		if(ip->tot_len != cs->cs_ip.tot_len &&
406		   ntohs(cs->cs_ip.tot_len) == hlen)
407			break;
408		goto uncompressed;
 
409	case SPECIAL_I:
410	case SPECIAL_D:
411		/* actual changes match one of our special case encodings --
412		 * send packet uncompressed.
413		 */
414		goto uncompressed;
415	case NEW_S|NEW_A:
416		if(deltaS == deltaA &&
417		    deltaS == ntohs(cs->cs_ip.tot_len) - hlen){
418			/* special case for echoed terminal traffic */
419			changes = SPECIAL_I;
420			cp = new_seq;
421		}
422		break;
423	case NEW_S:
424		if(deltaS == ntohs(cs->cs_ip.tot_len) - hlen){
425			/* special case for data xfer */
426			changes = SPECIAL_D;
427			cp = new_seq;
428		}
429		break;
430	}
431	deltaS = ntohs(ip->id) - ntohs(cs->cs_ip.id);
432	if(deltaS != 1){
433		cp = encode(cp,deltaS);
434		changes |= NEW_I;
435	}
436	if(th->psh)
437		changes |= TCP_PUSH_BIT;
438	/* Grab the cksum before we overwrite it below.  Then update our
439	 * state with this packet's header.
440	 */
441	csum = th->check;
442	memcpy(&cs->cs_ip,ip,20);
443	memcpy(&cs->cs_tcp,th,20);
444	/* We want to use the original packet as our compressed packet.
445	 * (cp - new_seq) is the number of bytes we need for compressed
446	 * sequence numbers.  In addition we need one byte for the change
447	 * mask, one for the connection id and two for the tcp checksum.
448	 * So, (cp - new_seq) + 4 bytes of header are needed.
449	 */
450	deltaS = cp - new_seq;
451	if(compress_cid == 0 || comp->xmit_current != cs->cs_this){
452		cp = ocp;
453		*cpp = ocp;
454		*cp++ = changes | NEW_C;
455		*cp++ = cs->cs_this;
456		comp->xmit_current = cs->cs_this;
457	} else {
458		cp = ocp;
459		*cpp = ocp;
460		*cp++ = changes;
461	}
462	*(__sum16 *)cp = csum;
463	cp += 2;
464/* deltaS is now the size of the change section of the compressed header */
465	memcpy(cp,new_seq,deltaS);	/* Write list of deltas */
466	memcpy(cp+deltaS,icp+hlen,isize-hlen);
467	comp->sls_o_compressed++;
468	ocp[0] |= SL_TYPE_COMPRESSED_TCP;
469	return isize - hlen + deltaS + (cp - ocp);
470
471	/* Update connection state cs & send uncompressed packet (i.e.,
472	 * a regular ip/tcp packet but with the 'conversation id' we hope
473	 * to use on future compressed packets in the protocol field).
474	 */
475uncompressed:
476	memcpy(&cs->cs_ip,ip,20);
477	memcpy(&cs->cs_tcp,th,20);
478	if (ip->ihl > 5)
479	  memcpy(cs->cs_ipopt, ip+1, ((ip->ihl) - 5) * 4);
480	if (th->doff > 5)
481	  memcpy(cs->cs_tcpopt, th+1, ((th->doff) - 5) * 4);
482	comp->xmit_current = cs->cs_this;
483	comp->sls_o_uncompressed++;
484	memcpy(ocp, icp, isize);
485	*cpp = ocp;
486	ocp[9] = cs->cs_this;
487	ocp[0] |= SL_TYPE_UNCOMPRESSED_TCP;
488	return isize;
489}
490
491
492int
493slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize)
494{
495	int changes;
496	long x;
497	struct tcphdr *thp;
498	struct iphdr *ip;
499	struct cstate *cs;
500	int len, hdrlen;
501	unsigned char *cp = icp;
502
503	/* We've got a compressed packet; read the change byte */
504	comp->sls_i_compressed++;
505	if(isize < 3){
506		comp->sls_i_error++;
507		return 0;
508	}
509	changes = *cp++;
510	if(changes & NEW_C){
511		/* Make sure the state index is in range, then grab the state.
512		 * If we have a good state index, clear the 'discard' flag.
513		 */
514		x = *cp++;	/* Read conn index */
515		if(x < 0 || x > comp->rslot_limit)
516			goto bad;
517
518		/* Check if the cstate is initialized */
519		if (!comp->rstate[x].initialized)
520			goto bad;
521
522		comp->flags &=~ SLF_TOSS;
523		comp->recv_current = x;
524	} else {
525		/* this packet has an implicit state index.  If we've
526		 * had a line error since the last time we got an
527		 * explicit state index, we have to toss the packet. */
528		if(comp->flags & SLF_TOSS){
529			comp->sls_i_tossed++;
530			return 0;
531		}
532	}
533	cs = &comp->rstate[comp->recv_current];
534	thp = &cs->cs_tcp;
535	ip = &cs->cs_ip;
536
537	thp->check = *(__sum16 *)cp;
538	cp += 2;
539
540	thp->psh = (changes & TCP_PUSH_BIT) ? 1 : 0;
541/*
542 * we can use the same number for the length of the saved header and
543 * the current one, because the packet wouldn't have been sent
544 * as compressed unless the options were the same as the previous one
545 */
546
547	hdrlen = ip->ihl * 4 + thp->doff * 4;
548
549	switch(changes & SPECIALS_MASK){
550	case SPECIAL_I:		/* Echoed terminal traffic */
551		{
552		short i;
553		i = ntohs(ip->tot_len) - hdrlen;
554		thp->ack_seq = htonl( ntohl(thp->ack_seq) + i);
555		thp->seq = htonl( ntohl(thp->seq) + i);
556		}
557		break;
558
559	case SPECIAL_D:			/* Unidirectional data */
560		thp->seq = htonl( ntohl(thp->seq) +
561				  ntohs(ip->tot_len) - hdrlen);
562		break;
563
564	default:
565		if(changes & NEW_U){
566			thp->urg = 1;
567			if((x = decode(&cp)) == -1) {
568				goto bad;
569			}
570			thp->urg_ptr = htons(x);
571		} else
572			thp->urg = 0;
573		if(changes & NEW_W){
574			if((x = decode(&cp)) == -1) {
575				goto bad;
576			}
577			thp->window = htons( ntohs(thp->window) + x);
578		}
579		if(changes & NEW_A){
580			if((x = decode(&cp)) == -1) {
581				goto bad;
582			}
583			thp->ack_seq = htonl( ntohl(thp->ack_seq) + x);
584		}
585		if(changes & NEW_S){
586			if((x = decode(&cp)) == -1) {
587				goto bad;
588			}
589			thp->seq = htonl( ntohl(thp->seq) + x);
590		}
591		break;
592	}
593	if(changes & NEW_I){
594		if((x = decode(&cp)) == -1) {
595			goto bad;
596		}
597		ip->id = htons (ntohs (ip->id) + x);
598	} else
599		ip->id = htons (ntohs (ip->id) + 1);
600
601	/*
602	 * At this point, cp points to the first byte of data in the
603	 * packet.  Put the reconstructed TCP and IP headers back on the
604	 * packet.  Recalculate IP checksum (but not TCP checksum).
605	 */
606
607	len = isize - (cp - icp);
608	if (len < 0)
609		goto bad;
610	len += hdrlen;
611	ip->tot_len = htons(len);
612	ip->check = 0;
613
614	memmove(icp + hdrlen, cp, len - hdrlen);
615
616	cp = icp;
617	memcpy(cp, ip, 20);
618	cp += 20;
619
620	if (ip->ihl > 5) {
621	  memcpy(cp, cs->cs_ipopt, (ip->ihl - 5) * 4);
622	  cp += (ip->ihl - 5) * 4;
623	}
624
625	put_unaligned(ip_fast_csum(icp, ip->ihl),
626		      &((struct iphdr *)icp)->check);
627
628	memcpy(cp, thp, 20);
629	cp += 20;
630
631	if (thp->doff > 5) {
632	  memcpy(cp, cs->cs_tcpopt, ((thp->doff) - 5) * 4);
633	  cp += ((thp->doff) - 5) * 4;
634	}
635
636	return len;
637bad:
638	comp->sls_i_error++;
639	return slhc_toss( comp );
640}
641
642
643int
644slhc_remember(struct slcompress *comp, unsigned char *icp, int isize)
645{
646	const struct tcphdr *th;
 
 
647	unsigned char index;
648	struct iphdr *iph;
649	struct cstate *cs;
650	unsigned int ihl;
651
652	/* The packet is shorter than a legal IP header.
653	 * Also make sure isize is positive.
654	 */
655	if (isize < (int)sizeof(struct iphdr)) {
656runt:
657		comp->sls_i_runt++;
658		return slhc_toss(comp);
659	}
660	iph = (struct iphdr *)icp;
661	/* Peek at the IP header's IHL field to find its length */
662	ihl = iph->ihl;
663	/* The IP header length field is too small,
664	 * or packet is shorter than the IP header followed
665	 * by minimal tcp header.
666	 */
667	if (ihl < 5 || isize < ihl * 4 + sizeof(struct tcphdr))
668		goto runt;
669
670	index = iph->protocol;
671	iph->protocol = IPPROTO_TCP;
672
673	if (ip_fast_csum(icp, ihl)) {
674		/* Bad IP header checksum; discard */
675		comp->sls_i_badcheck++;
676		return slhc_toss(comp);
677	}
678	if (index > comp->rslot_limit) {
679		comp->sls_i_error++;
680		return slhc_toss(comp);
681	}
682	th = (struct tcphdr *)(icp + ihl * 4);
683	if (th->doff < sizeof(struct tcphdr) / 4)
684		goto runt;
685	if (isize < ihl * 4 + th->doff * 4)
686		goto runt;
687	/* Update local state */
688	cs = &comp->rstate[comp->recv_current = index];
689	comp->flags &=~ SLF_TOSS;
690	memcpy(&cs->cs_ip, iph, sizeof(*iph));
691	memcpy(&cs->cs_tcp, th, sizeof(*th));
692	if (ihl > 5)
693	  memcpy(cs->cs_ipopt, &iph[1], (ihl - 5) * 4);
694	if (th->doff > 5)
695	  memcpy(cs->cs_tcpopt, &th[1], (th->doff - 5) * 4);
696	cs->cs_hsize = ihl*2 + th->doff*2;
697	cs->initialized = true;
698	/* Put headers back on packet
699	 * Neither header checksum is recalculated
700	 */
701	comp->sls_i_uncompressed++;
702	return isize;
703}
704
705int
706slhc_toss(struct slcompress *comp)
707{
708	if ( comp == NULLSLCOMPR )
709		return 0;
710
711	comp->flags |= SLF_TOSS;
712	return 0;
713}
714
715#else /* CONFIG_INET */
716
717int
718slhc_toss(struct slcompress *comp)
719{
720  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_toss");
721  return -EINVAL;
722}
723int
724slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize)
725{
726  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_uncompress");
727  return -EINVAL;
728}
729int
730slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
731	unsigned char *ocp, unsigned char **cpp, int compress_cid)
732{
733  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_compress");
734  return -EINVAL;
735}
736
737int
738slhc_remember(struct slcompress *comp, unsigned char *icp, int isize)
739{
740  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_remember");
741  return -EINVAL;
742}
743
744void
745slhc_free(struct slcompress *comp)
746{
747  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_free");
748}
749struct slcompress *
750slhc_init(int rslots, int tslots)
751{
752  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_init");
753  return NULL;
754}
755
756#endif /* CONFIG_INET */
757
758/* VJ header compression */
759EXPORT_SYMBOL(slhc_init);
760EXPORT_SYMBOL(slhc_free);
761EXPORT_SYMBOL(slhc_remember);
762EXPORT_SYMBOL(slhc_compress);
763EXPORT_SYMBOL(slhc_uncompress);
764EXPORT_SYMBOL(slhc_toss);
765
766MODULE_DESCRIPTION("Compression helpers for SLIP (serial line)");
767MODULE_LICENSE("Dual BSD/GPL");