source: S-port/trunk/Middlewares/Third_Party/LwIP/src/netif/ppp/vj.c

Last change on this file was 1, checked in by AlexLir, 3 years ago
File size: 20.1 KB
Line 
1/*
2 * Routines to compress and uncompess 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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
19 *
20 * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
21 * Initial distribution.
22 *
23 * Modified June 1993 by Paul Mackerras, paulus@cs.anu.edu.au,
24 * so that the entire packet being decompressed doesn't have
25 * to be in contiguous memory (just the compressed header).
26 *
27 * Modified March 1998 by Guy Lancaster, glanca@gesn.com,
28 * for a 16 bit processor.
29 */
30
31#include "netif/ppp/ppp_opts.h"
32#if PPP_SUPPORT && VJ_SUPPORT /* don't build if not configured for use in lwipopts.h */
33
34#include "netif/ppp/ppp_impl.h"
35#include "netif/ppp/pppdebug.h"
36
37#include "netif/ppp/vj.h"
38
39#include <string.h>
40
41#if LINK_STATS
42#define INCR(counter) ++comp->stats.counter
43#else
44#define INCR(counter)
45#endif
46
47void
48vj_compress_init(struct vjcompress *comp)
49{
50 u8_t i;
51 struct cstate *tstate = comp->tstate;
52
53#if MAX_SLOTS == 0
54 memset((char *)comp, 0, sizeof(*comp));
55#endif
56 comp->maxSlotIndex = MAX_SLOTS - 1;
57 comp->compressSlot = 0; /* Disable slot ID compression by default. */
58 for (i = MAX_SLOTS - 1; i > 0; --i) {
59 tstate[i].cs_id = i;
60 tstate[i].cs_next = &tstate[i - 1];
61 }
62 tstate[0].cs_next = &tstate[MAX_SLOTS - 1];
63 tstate[0].cs_id = 0;
64 comp->last_cs = &tstate[0];
65 comp->last_recv = 255;
66 comp->last_xmit = 255;
67 comp->flags = VJF_TOSS;
68}
69
70
71/* ENCODE encodes a number that is known to be non-zero. ENCODEZ
72 * checks for zero (since zero has to be encoded in the long, 3 byte
73 * form).
74 */
75#define ENCODE(n) { \
76 if ((u16_t)(n) >= 256) { \
77 *cp++ = 0; \
78 cp[1] = (u8_t)(n); \
79 cp[0] = (u8_t)((n) >> 8); \
80 cp += 2; \
81 } else { \
82 *cp++ = (u8_t)(n); \
83 } \
84}
85#define ENCODEZ(n) { \
86 if ((u16_t)(n) >= 256 || (u16_t)(n) == 0) { \
87 *cp++ = 0; \
88 cp[1] = (u8_t)(n); \
89 cp[0] = (u8_t)((n) >> 8); \
90 cp += 2; \
91 } else { \
92 *cp++ = (u8_t)(n); \
93 } \
94}
95
96#define DECODEL(f) { \
97 if (*cp == 0) {\
98 u32_t tmp_ = lwip_ntohl(f) + ((cp[1] << 8) | cp[2]); \
99 (f) = lwip_htonl(tmp_); \
100 cp += 3; \
101 } else { \
102 u32_t tmp_ = lwip_ntohl(f) + (u32_t)*cp++; \
103 (f) = lwip_htonl(tmp_); \
104 } \
105}
106
107#define DECODES(f) { \
108 if (*cp == 0) {\
109 u16_t tmp_ = lwip_ntohs(f) + (((u16_t)cp[1] << 8) | cp[2]); \
110 (f) = lwip_htons(tmp_); \
111 cp += 3; \
112 } else { \
113 u16_t tmp_ = lwip_ntohs(f) + (u16_t)*cp++; \
114 (f) = lwip_htons(tmp_); \
115 } \
116}
117
118#define DECODEU(f) { \
119 if (*cp == 0) {\
120 (f) = lwip_htons(((u16_t)cp[1] << 8) | cp[2]); \
121 cp += 3; \
122 } else { \
123 (f) = lwip_htons((u16_t)*cp++); \
124 } \
125}
126
127/* Helper structures for unaligned *u32_t and *u16_t accesses */
128#ifdef PACK_STRUCT_USE_INCLUDES
129# include "arch/bpstruct.h"
130#endif
131PACK_STRUCT_BEGIN
132struct vj_u32_t {
133 PACK_STRUCT_FIELD(u32_t v);
134} PACK_STRUCT_STRUCT;
135PACK_STRUCT_END
136#ifdef PACK_STRUCT_USE_INCLUDES
137# include "arch/epstruct.h"
138#endif
139
140#ifdef PACK_STRUCT_USE_INCLUDES
141# include "arch/bpstruct.h"
142#endif
143PACK_STRUCT_BEGIN
144struct vj_u16_t {
145 PACK_STRUCT_FIELD(u16_t v);
146} PACK_STRUCT_STRUCT;
147PACK_STRUCT_END
148#ifdef PACK_STRUCT_USE_INCLUDES
149# include "arch/epstruct.h"
150#endif
151
152/*
153 * vj_compress_tcp - Attempt to do Van Jacobson header compression on a
154 * packet. This assumes that nb and comp are not null and that the first
155 * buffer of the chain contains a valid IP header.
156 * Return the VJ type code indicating whether or not the packet was
157 * compressed.
158 */
159u8_t
160vj_compress_tcp(struct vjcompress *comp, struct pbuf **pb)
161{
162 struct pbuf *np = *pb;
163 struct ip_hdr *ip = (struct ip_hdr *)np->payload;
164 struct cstate *cs = comp->last_cs->cs_next;
165 u16_t ilen = IPH_HL(ip);
166 u16_t hlen;
167 struct tcp_hdr *oth;
168 struct tcp_hdr *th;
169 u16_t deltaS, deltaA = 0;
170 u32_t deltaL;
171 u32_t changes = 0;
172 u8_t new_seq[16];
173 u8_t *cp = new_seq;
174
175 /*
176 * Check that the packet is IP proto TCP.
177 */
178 if (IPH_PROTO(ip) != IP_PROTO_TCP) {
179 return (TYPE_IP);
180 }
181
182 /*
183 * Bail if this is an IP fragment or if the TCP packet isn't
184 * `compressible' (i.e., ACK isn't set or some other control bit is
185 * set).
186 */
187 if ((IPH_OFFSET(ip) & PP_HTONS(0x3fff)) || np->tot_len < 40) {
188 return (TYPE_IP);
189 }
190 th = (struct tcp_hdr *)&((struct vj_u32_t*)ip)[ilen];
191 if ((TCPH_FLAGS(th) & (TCP_SYN|TCP_FIN|TCP_RST|TCP_ACK)) != TCP_ACK) {
192 return (TYPE_IP);
193 }
194
195 /* Check that the TCP/IP headers are contained in the first buffer. */
196 hlen = ilen + TCPH_HDRLEN(th);
197 hlen <<= 2;
198 if (np->len < hlen) {
199 PPPDEBUG(LOG_INFO, ("vj_compress_tcp: header len %d spans buffers\n", hlen));
200 return (TYPE_IP);
201 }
202
203 /* TCP stack requires that we don't change the packet payload, therefore we copy
204 * the whole packet before compression. */
205 np = pbuf_clone(PBUF_RAW, PBUF_RAM, *pb);
206 if (!np) {
207 return (TYPE_IP);
208 }
209
210 *pb = np;
211 ip = (struct ip_hdr *)np->payload;
212
213 /*
214 * Packet is compressible -- we're going to send either a
215 * COMPRESSED_TCP or UNCOMPRESSED_TCP packet. Either way we need
216 * to locate (or create) the connection state. Special case the
217 * most recently used connection since it's most likely to be used
218 * again & we don't have to do any reordering if it's used.
219 */
220 INCR(vjs_packets);
221 if (!ip4_addr_cmp(&ip->src, &cs->cs_ip.src)
222 || !ip4_addr_cmp(&ip->dest, &cs->cs_ip.dest)
223 || (*(struct vj_u32_t*)th).v != (((struct vj_u32_t*)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]).v) {
224 /*
225 * Wasn't the first -- search for it.
226 *
227 * States are kept in a circularly linked list with
228 * last_cs pointing to the end of the list. The
229 * list is kept in lru order by moving a state to the
230 * head of the list whenever it is referenced. Since
231 * the list is short and, empirically, the connection
232 * we want is almost always near the front, we locate
233 * states via linear search. If we don't find a state
234 * for the datagram, the oldest state is (re-)used.
235 */
236 struct cstate *lcs;
237 struct cstate *lastcs = comp->last_cs;
238
239 do {
240 lcs = cs; cs = cs->cs_next;
241 INCR(vjs_searches);
242 if (ip4_addr_cmp(&ip->src, &cs->cs_ip.src)
243 && ip4_addr_cmp(&ip->dest, &cs->cs_ip.dest)
244 && (*(struct vj_u32_t*)th).v == (((struct vj_u32_t*)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]).v) {
245 goto found;
246 }
247 } while (cs != lastcs);
248
249 /*
250 * Didn't find it -- re-use oldest cstate. Send an
251 * uncompressed packet that tells the other side what
252 * connection number we're using for this conversation.
253 * Note that since the state list is circular, the oldest
254 * state points to the newest and we only need to set
255 * last_cs to update the lru linkage.
256 */
257 INCR(vjs_misses);
258 comp->last_cs = lcs;
259 goto uncompressed;
260
261 found:
262 /*
263 * Found it -- move to the front on the connection list.
264 */
265 if (cs == lastcs) {
266 comp->last_cs = lcs;
267 } else {
268 lcs->cs_next = cs->cs_next;
269 cs->cs_next = lastcs->cs_next;
270 lastcs->cs_next = cs;
271 }
272 }
273
274 oth = (struct tcp_hdr *)&((struct vj_u32_t*)&cs->cs_ip)[ilen];
275 deltaS = ilen;
276
277 /*
278 * Make sure that only what we expect to change changed. The first
279 * line of the `if' checks the IP protocol version, header length &
280 * type of service. The 2nd line checks the "Don't fragment" bit.
281 * The 3rd line checks the time-to-live and protocol (the protocol
282 * check is unnecessary but costless). The 4th line checks the TCP
283 * header length. The 5th line checks IP options, if any. The 6th
284 * line checks TCP options, if any. If any of these things are
285 * different between the previous & current datagram, we send the
286 * current datagram `uncompressed'.
287 */
288 if ((((struct vj_u16_t*)ip)[0]).v != (((struct vj_u16_t*)&cs->cs_ip)[0]).v
289 || (((struct vj_u16_t*)ip)[3]).v != (((struct vj_u16_t*)&cs->cs_ip)[3]).v
290 || (((struct vj_u16_t*)ip)[4]).v != (((struct vj_u16_t*)&cs->cs_ip)[4]).v
291 || TCPH_HDRLEN(th) != TCPH_HDRLEN(oth)
292 || (deltaS > 5 && BCMP(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2))
293 || (TCPH_HDRLEN(th) > 5 && BCMP(th + 1, oth + 1, (TCPH_HDRLEN(th) - 5) << 2))) {
294 goto uncompressed;
295 }
296
297 /*
298 * Figure out which of the changing fields changed. The
299 * receiver expects changes in the order: urgent, window,
300 * ack, seq (the order minimizes the number of temporaries
301 * needed in this section of code).
302 */
303 if (TCPH_FLAGS(th) & TCP_URG) {
304 deltaS = lwip_ntohs(th->urgp);
305 ENCODEZ(deltaS);
306 changes |= NEW_U;
307 } else if (th->urgp != oth->urgp) {
308 /* argh! URG not set but urp changed -- a sensible
309 * implementation should never do this but RFC793
310 * doesn't prohibit the change so we have to deal
311 * with it. */
312 goto uncompressed;
313 }
314
315 if ((deltaS = (u16_t)(lwip_ntohs(th->wnd) - lwip_ntohs(oth->wnd))) != 0) {
316 ENCODE(deltaS);
317 changes |= NEW_W;
318 }
319
320 if ((deltaL = lwip_ntohl(th->ackno) - lwip_ntohl(oth->ackno)) != 0) {
321 if (deltaL > 0xffff) {
322 goto uncompressed;
323 }
324 deltaA = (u16_t)deltaL;
325 ENCODE(deltaA);
326 changes |= NEW_A;
327 }
328
329 if ((deltaL = lwip_ntohl(th->seqno) - lwip_ntohl(oth->seqno)) != 0) {
330 if (deltaL > 0xffff) {
331 goto uncompressed;
332 }
333 deltaS = (u16_t)deltaL;
334 ENCODE(deltaS);
335 changes |= NEW_S;
336 }
337
338 switch(changes) {
339 case 0:
340 /*
341 * Nothing changed. If this packet contains data and the
342 * last one didn't, this is probably a data packet following
343 * an ack (normal on an interactive connection) and we send
344 * it compressed. Otherwise it's probably a retransmit,
345 * retransmitted ack or window probe. Send it uncompressed
346 * in case the other side missed the compressed version.
347 */
348 if (IPH_LEN(ip) != IPH_LEN(&cs->cs_ip) &&
349 lwip_ntohs(IPH_LEN(&cs->cs_ip)) == hlen) {
350 break;
351 }
352 /* no break */
353 /* fall through */
354
355 case SPECIAL_I:
356 case SPECIAL_D:
357 /*
358 * actual changes match one of our special case encodings --
359 * send packet uncompressed.
360 */
361 goto uncompressed;
362
363 case NEW_S|NEW_A:
364 if (deltaS == deltaA && deltaS == lwip_ntohs(IPH_LEN(&cs->cs_ip)) - hlen) {
365 /* special case for echoed terminal traffic */
366 changes = SPECIAL_I;
367 cp = new_seq;
368 }
369 break;
370
371 case NEW_S:
372 if (deltaS == lwip_ntohs(IPH_LEN(&cs->cs_ip)) - hlen) {
373 /* special case for data xfer */
374 changes = SPECIAL_D;
375 cp = new_seq;
376 }
377 break;
378 default:
379 break;
380 }
381
382 deltaS = (u16_t)(lwip_ntohs(IPH_ID(ip)) - lwip_ntohs(IPH_ID(&cs->cs_ip)));
383 if (deltaS != 1) {
384 ENCODEZ(deltaS);
385 changes |= NEW_I;
386 }
387 if (TCPH_FLAGS(th) & TCP_PSH) {
388 changes |= TCP_PUSH_BIT;
389 }
390 /*
391 * Grab the cksum before we overwrite it below. Then update our
392 * state with this packet's header.
393 */
394 deltaA = lwip_ntohs(th->chksum);
395 MEMCPY(&cs->cs_ip, ip, hlen);
396
397 /*
398 * We want to use the original packet as our compressed packet.
399 * (cp - new_seq) is the number of bytes we need for compressed
400 * sequence numbers. In addition we need one byte for the change
401 * mask, one for the connection id and two for the tcp checksum.
402 * So, (cp - new_seq) + 4 bytes of header are needed. hlen is how
403 * many bytes of the original packet to toss so subtract the two to
404 * get the new packet size.
405 */
406 deltaS = (u16_t)(cp - new_seq);
407 if (!comp->compressSlot || comp->last_xmit != cs->cs_id) {
408 comp->last_xmit = cs->cs_id;
409 hlen -= deltaS + 4;
410 if (pbuf_remove_header(np, hlen)){
411 /* Can we cope with this failing? Just assert for now */
412 LWIP_ASSERT("pbuf_remove_header failed\n", 0);
413 }
414 cp = (u8_t*)np->payload;
415 *cp++ = (u8_t)(changes | NEW_C);
416 *cp++ = cs->cs_id;
417 } else {
418 hlen -= deltaS + 3;
419 if (pbuf_remove_header(np, hlen)) {
420 /* Can we cope with this failing? Just assert for now */
421 LWIP_ASSERT("pbuf_remove_header failed\n", 0);
422 }
423 cp = (u8_t*)np->payload;
424 *cp++ = (u8_t)changes;
425 }
426 *cp++ = (u8_t)(deltaA >> 8);
427 *cp++ = (u8_t)deltaA;
428 MEMCPY(cp, new_seq, deltaS);
429 INCR(vjs_compressed);
430 return (TYPE_COMPRESSED_TCP);
431
432 /*
433 * Update connection state cs & send uncompressed packet (that is,
434 * a regular ip/tcp packet but with the 'conversation id' we hope
435 * to use on future compressed packets in the protocol field).
436 */
437uncompressed:
438 MEMCPY(&cs->cs_ip, ip, hlen);
439 IPH_PROTO_SET(ip, cs->cs_id);
440 comp->last_xmit = cs->cs_id;
441 return (TYPE_UNCOMPRESSED_TCP);
442}
443
444/*
445 * Called when we may have missed a packet.
446 */
447void
448vj_uncompress_err(struct vjcompress *comp)
449{
450 comp->flags |= VJF_TOSS;
451 INCR(vjs_errorin);
452}
453
454/*
455 * "Uncompress" a packet of type TYPE_UNCOMPRESSED_TCP.
456 * Return 0 on success, -1 on failure.
457 */
458int
459vj_uncompress_uncomp(struct pbuf *nb, struct vjcompress *comp)
460{
461 u32_t hlen;
462 struct cstate *cs;
463 struct ip_hdr *ip;
464
465 ip = (struct ip_hdr *)nb->payload;
466 hlen = IPH_HL(ip) << 2;
467 if (IPH_PROTO(ip) >= MAX_SLOTS
468 || hlen + sizeof(struct tcp_hdr) > nb->len
469 || (hlen += TCPH_HDRLEN_BYTES((struct tcp_hdr *)&((char *)ip)[hlen]))
470 > nb->len
471 || hlen > MAX_HDR) {
472 PPPDEBUG(LOG_INFO, ("vj_uncompress_uncomp: bad cid=%d, hlen=%d buflen=%d\n",
473 IPH_PROTO(ip), hlen, nb->len));
474 vj_uncompress_err(comp);
475 return -1;
476 }
477 cs = &comp->rstate[comp->last_recv = IPH_PROTO(ip)];
478 comp->flags &=~ VJF_TOSS;
479 IPH_PROTO_SET(ip, IP_PROTO_TCP);
480 /* copy from/to bigger buffers checked above instead of cs->cs_ip and ip
481 just to help static code analysis to see this is correct ;-) */
482 MEMCPY(&cs->cs_hdr, nb->payload, hlen);
483 cs->cs_hlen = (u16_t)hlen;
484 INCR(vjs_uncompressedin);
485 return 0;
486}
487
488/*
489 * Uncompress a packet of type TYPE_COMPRESSED_TCP.
490 * The packet is composed of a buffer chain and the first buffer
491 * must contain an accurate chain length.
492 * The first buffer must include the entire compressed TCP/IP header.
493 * This procedure replaces the compressed header with the uncompressed
494 * header and returns the length of the VJ header.
495 */
496int
497vj_uncompress_tcp(struct pbuf **nb, struct vjcompress *comp)
498{
499 u8_t *cp;
500 struct tcp_hdr *th;
501 struct cstate *cs;
502 struct vj_u16_t *bp;
503 struct pbuf *n0 = *nb;
504 u32_t tmp;
505 u32_t vjlen, hlen, changes;
506
507 INCR(vjs_compressedin);
508 cp = (u8_t*)n0->payload;
509 changes = *cp++;
510 if (changes & NEW_C) {
511 /*
512 * Make sure the state index is in range, then grab the state.
513 * If we have a good state index, clear the 'discard' flag.
514 */
515 if (*cp >= MAX_SLOTS) {
516 PPPDEBUG(LOG_INFO, ("vj_uncompress_tcp: bad cid=%d\n", *cp));
517 goto bad;
518 }
519
520 comp->flags &=~ VJF_TOSS;
521 comp->last_recv = *cp++;
522 } else {
523 /*
524 * this packet has an implicit state index. If we've
525 * had a line error since the last time we got an
526 * explicit state index, we have to toss the packet.
527 */
528 if (comp->flags & VJF_TOSS) {
529 PPPDEBUG(LOG_INFO, ("vj_uncompress_tcp: tossing\n"));
530 INCR(vjs_tossed);
531 return (-1);
532 }
533 }
534 cs = &comp->rstate[comp->last_recv];
535 hlen = IPH_HL(&cs->cs_ip) << 2;
536 th = (struct tcp_hdr *)&((u8_t*)&cs->cs_ip)[hlen];
537 th->chksum = lwip_htons((*cp << 8) | cp[1]);
538 cp += 2;
539 if (changes & TCP_PUSH_BIT) {
540 TCPH_SET_FLAG(th, TCP_PSH);
541 } else {
542 TCPH_UNSET_FLAG(th, TCP_PSH);
543 }
544
545 switch (changes & SPECIALS_MASK) {
546 case SPECIAL_I:
547 {
548 u32_t i = lwip_ntohs(IPH_LEN(&cs->cs_ip)) - cs->cs_hlen;
549 /* some compilers can't nest inline assembler.. */
550 tmp = lwip_ntohl(th->ackno) + i;
551 th->ackno = lwip_htonl(tmp);
552 tmp = lwip_ntohl(th->seqno) + i;
553 th->seqno = lwip_htonl(tmp);
554 }
555 break;
556
557 case SPECIAL_D:
558 /* some compilers can't nest inline assembler.. */
559 tmp = lwip_ntohl(th->seqno) + lwip_ntohs(IPH_LEN(&cs->cs_ip)) - cs->cs_hlen;
560 th->seqno = lwip_htonl(tmp);
561 break;
562
563 default:
564 if (changes & NEW_U) {
565 TCPH_SET_FLAG(th, TCP_URG);
566 DECODEU(th->urgp);
567 } else {
568 TCPH_UNSET_FLAG(th, TCP_URG);
569 }
570 if (changes & NEW_W) {
571 DECODES(th->wnd);
572 }
573 if (changes & NEW_A) {
574 DECODEL(th->ackno);
575 }
576 if (changes & NEW_S) {
577 DECODEL(th->seqno);
578 }
579 break;
580 }
581 if (changes & NEW_I) {
582 DECODES(cs->cs_ip._id);
583 } else {
584 IPH_ID_SET(&cs->cs_ip, lwip_ntohs(IPH_ID(&cs->cs_ip)) + 1);
585 IPH_ID_SET(&cs->cs_ip, lwip_htons(IPH_ID(&cs->cs_ip)));
586 }
587
588 /*
589 * At this point, cp points to the first byte of data in the
590 * packet. Fill in the IP total length and update the IP
591 * header checksum.
592 */
593 vjlen = (u16_t)(cp - (u8_t*)n0->payload);
594 if (n0->len < vjlen) {
595 /*
596 * We must have dropped some characters (crc should detect
597 * this but the old slip framing won't)
598 */
599 PPPDEBUG(LOG_INFO, ("vj_uncompress_tcp: head buffer %d too short %d\n",
600 n0->len, vjlen));
601 goto bad;
602 }
603
604#if BYTE_ORDER == LITTLE_ENDIAN
605 tmp = n0->tot_len - vjlen + cs->cs_hlen;
606 IPH_LEN_SET(&cs->cs_ip, lwip_htons((u16_t)tmp));
607#else
608 IPH_LEN_SET(&cs->cs_ip, lwip_htons(n0->tot_len - vjlen + cs->cs_hlen));
609#endif
610
611 /* recompute the ip header checksum */
612 bp = (struct vj_u16_t*) &cs->cs_ip;
613 IPH_CHKSUM_SET(&cs->cs_ip, 0);
614 for (tmp = 0; hlen > 0; hlen -= 2) {
615 tmp += (*bp++).v;
616 }
617 tmp = (tmp & 0xffff) + (tmp >> 16);
618 tmp = (tmp & 0xffff) + (tmp >> 16);
619 IPH_CHKSUM_SET(&cs->cs_ip, (u16_t)(~tmp));
620
621 /* Remove the compressed header and prepend the uncompressed header. */
622 if (pbuf_remove_header(n0, vjlen)) {
623 /* Can we cope with this failing? Just assert for now */
624 LWIP_ASSERT("pbuf_remove_header failed\n", 0);
625 goto bad;
626 }
627
628 if(LWIP_MEM_ALIGN(n0->payload) != n0->payload) {
629 struct pbuf *np;
630
631#if IP_FORWARD
632 /* If IP forwarding is enabled we are using a PBUF_LINK packet type so
633 * the packet is being allocated with enough header space to be
634 * forwarded (to Ethernet for example).
635 */
636 np = pbuf_alloc(PBUF_LINK, n0->len + cs->cs_hlen, PBUF_POOL);
637#else /* IP_FORWARD */
638 np = pbuf_alloc(PBUF_RAW, n0->len + cs->cs_hlen, PBUF_POOL);
639#endif /* IP_FORWARD */
640 if(!np) {
641 PPPDEBUG(LOG_WARNING, ("vj_uncompress_tcp: realign failed\n"));
642 goto bad;
643 }
644
645 if (pbuf_remove_header(np, cs->cs_hlen)) {
646 /* Can we cope with this failing? Just assert for now */
647 LWIP_ASSERT("pbuf_remove_header failed\n", 0);
648 goto bad;
649 }
650
651 pbuf_take(np, n0->payload, n0->len);
652
653 if(n0->next) {
654 pbuf_chain(np, n0->next);
655 pbuf_dechain(n0);
656 }
657 pbuf_free(n0);
658 n0 = np;
659 }
660
661 if (pbuf_add_header(n0, cs->cs_hlen)) {
662 struct pbuf *np;
663
664 LWIP_ASSERT("vj_uncompress_tcp: cs->cs_hlen <= PBUF_POOL_BUFSIZE", cs->cs_hlen <= PBUF_POOL_BUFSIZE);
665 np = pbuf_alloc(PBUF_RAW, cs->cs_hlen, PBUF_POOL);
666 if(!np) {
667 PPPDEBUG(LOG_WARNING, ("vj_uncompress_tcp: prepend failed\n"));
668 goto bad;
669 }
670 pbuf_cat(np, n0);
671 n0 = np;
672 }
673 LWIP_ASSERT("n0->len >= cs->cs_hlen", n0->len >= cs->cs_hlen);
674 MEMCPY(n0->payload, &cs->cs_ip, cs->cs_hlen);
675
676 *nb = n0;
677
678 return vjlen;
679
680bad:
681 vj_uncompress_err(comp);
682 return (-1);
683}
684
685#endif /* PPP_SUPPORT && VJ_SUPPORT */
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