BadVPN – Blame information for rev 1
?pathlinks?
Rev | Author | Line No. | Line |
---|---|---|---|
1 | office | 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 | |||
47 | void |
||
48 | vj_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 |
||
131 | PACK_STRUCT_BEGIN |
||
132 | struct vj_u32_t { |
||
133 | PACK_STRUCT_FIELD(u32_t v); |
||
134 | } PACK_STRUCT_STRUCT; |
||
135 | PACK_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 |
||
143 | PACK_STRUCT_BEGIN |
||
144 | struct vj_u16_t { |
||
145 | PACK_STRUCT_FIELD(u16_t v); |
||
146 | } PACK_STRUCT_STRUCT; |
||
147 | PACK_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 | */ |
||
159 | u8_t |
||
160 | vj_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_POOL, *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 | */ |
||
437 | uncompressed: |
||
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 | */ |
||
447 | void |
||
448 | vj_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 | */ |
||
458 | int |
||
459 | vj_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 | */ |
||
496 | int |
||
497 | vj_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 | |||
680 | bad: |
||
681 | vj_uncompress_err(comp); |
||
682 | return (-1); |
||
683 | } |
||
684 | |||
685 | #endif /* PPP_SUPPORT && VJ_SUPPORT */ |