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Commit | Line | Data |
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1da177e4 LT |
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 | |
6aa20a22 | 45 | * - July 1995 Christos A. Polyzols |
1da177e4 LT |
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 | ||
1da177e4 | 53 | #include <linux/module.h> |
5a0e3ad6 | 54 | #include <linux/slab.h> |
1da177e4 LT |
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> | |
1da177e4 LT |
78 | #include <asm/uaccess.h> |
79 | #include <net/checksum.h> | |
80 | #include <asm/unaligned.h> | |
81 | ||
82 | static unsigned char *encode(unsigned char *cp, unsigned short n); | |
83 | static long decode(unsigned char **cpp); | |
84 | static unsigned char * put16(unsigned char *cp, unsigned short x); | |
85 | static unsigned short pull16(unsigned char **cpp); | |
86 | ||
87 | /* Initialize compression data structure | |
88 | * slots must be in range 0 to 255 (zero meaning no compression) | |
89 | */ | |
90 | struct slcompress * | |
91 | slhc_init(int rslots, int tslots) | |
92 | { | |
93 | register short i; | |
94 | register struct cstate *ts; | |
95 | struct slcompress *comp; | |
96 | ||
79690602 | 97 | comp = kzalloc(sizeof(struct slcompress), GFP_KERNEL); |
1da177e4 LT |
98 | if (! comp) |
99 | goto out_fail; | |
1da177e4 LT |
100 | |
101 | if ( rslots > 0 && rslots < 256 ) { | |
102 | size_t rsize = rslots * sizeof(struct cstate); | |
79690602 | 103 | comp->rstate = kzalloc(rsize, GFP_KERNEL); |
1da177e4 LT |
104 | if (! comp->rstate) |
105 | goto out_free; | |
1da177e4 LT |
106 | comp->rslot_limit = rslots - 1; |
107 | } | |
108 | ||
109 | if ( tslots > 0 && tslots < 256 ) { | |
110 | size_t tsize = tslots * sizeof(struct cstate); | |
79690602 | 111 | comp->tstate = kzalloc(tsize, GFP_KERNEL); |
1da177e4 LT |
112 | if (! comp->tstate) |
113 | goto out_free2; | |
1da177e4 LT |
114 | comp->tslot_limit = tslots - 1; |
115 | } | |
116 | ||
117 | comp->xmit_oldest = 0; | |
118 | comp->xmit_current = 255; | |
119 | comp->recv_current = 255; | |
120 | /* | |
121 | * don't accept any packets with implicit index until we get | |
122 | * one with an explicit index. Otherwise the uncompress code | |
123 | * will try to use connection 255, which is almost certainly | |
124 | * out of range | |
125 | */ | |
126 | comp->flags |= SLF_TOSS; | |
127 | ||
128 | if ( tslots > 0 ) { | |
129 | ts = comp->tstate; | |
130 | for(i = comp->tslot_limit; i > 0; --i){ | |
131 | ts[i].cs_this = i; | |
132 | ts[i].next = &(ts[i - 1]); | |
133 | } | |
134 | ts[0].next = &(ts[comp->tslot_limit]); | |
135 | ts[0].cs_this = 0; | |
136 | } | |
137 | return comp; | |
138 | ||
139 | out_free2: | |
79690602 | 140 | kfree(comp->rstate); |
1da177e4 | 141 | out_free: |
79690602 | 142 | kfree(comp); |
1da177e4 LT |
143 | out_fail: |
144 | return NULL; | |
145 | } | |
146 | ||
147 | ||
148 | /* Free a compression data structure */ | |
149 | void | |
150 | slhc_free(struct slcompress *comp) | |
151 | { | |
152 | if ( comp == NULLSLCOMPR ) | |
153 | return; | |
154 | ||
155 | if ( comp->tstate != NULLSLSTATE ) | |
156 | kfree( comp->tstate ); | |
157 | ||
158 | if ( comp->rstate != NULLSLSTATE ) | |
159 | kfree( comp->rstate ); | |
160 | ||
161 | kfree( comp ); | |
162 | } | |
163 | ||
164 | ||
165 | /* Put a short in host order into a char array in network order */ | |
166 | static inline unsigned char * | |
167 | put16(unsigned char *cp, unsigned short x) | |
168 | { | |
169 | *cp++ = x >> 8; | |
170 | *cp++ = x; | |
171 | ||
172 | return cp; | |
173 | } | |
174 | ||
175 | ||
176 | /* Encode a number */ | |
3c582b30 | 177 | static unsigned char * |
1da177e4 LT |
178 | encode(unsigned char *cp, unsigned short n) |
179 | { | |
180 | if(n >= 256 || n == 0){ | |
181 | *cp++ = 0; | |
182 | cp = put16(cp,n); | |
183 | } else { | |
184 | *cp++ = n; | |
185 | } | |
186 | return cp; | |
187 | } | |
188 | ||
189 | /* Pull a 16-bit integer in host order from buffer in network byte order */ | |
190 | static unsigned short | |
191 | pull16(unsigned char **cpp) | |
192 | { | |
193 | short rval; | |
194 | ||
195 | rval = *(*cpp)++; | |
196 | rval <<= 8; | |
197 | rval |= *(*cpp)++; | |
198 | return rval; | |
199 | } | |
200 | ||
201 | /* Decode a number */ | |
3c582b30 | 202 | static long |
1da177e4 LT |
203 | decode(unsigned char **cpp) |
204 | { | |
205 | register int x; | |
206 | ||
207 | x = *(*cpp)++; | |
208 | if(x == 0){ | |
209 | return pull16(cpp) & 0xffff; /* pull16 returns -1 on error */ | |
210 | } else { | |
211 | return x & 0xff; /* -1 if PULLCHAR returned error */ | |
212 | } | |
213 | } | |
214 | ||
215 | /* | |
216 | * icp and isize are the original packet. | |
217 | * ocp is a place to put a copy if necessary. | |
218 | * cpp is initially a pointer to icp. If the copy is used, | |
219 | * change it to ocp. | |
220 | */ | |
221 | ||
222 | int | |
223 | slhc_compress(struct slcompress *comp, unsigned char *icp, int isize, | |
224 | unsigned char *ocp, unsigned char **cpp, int compress_cid) | |
225 | { | |
226 | register struct cstate *ocs = &(comp->tstate[comp->xmit_oldest]); | |
227 | register struct cstate *lcs = ocs; | |
228 | register struct cstate *cs = lcs->next; | |
229 | register unsigned long deltaS, deltaA; | |
230 | register short changes = 0; | |
231 | int hlen; | |
232 | unsigned char new_seq[16]; | |
233 | register unsigned char *cp = new_seq; | |
234 | struct iphdr *ip; | |
235 | struct tcphdr *th, *oth; | |
7cd61888 | 236 | __sum16 csum; |
1da177e4 LT |
237 | |
238 | ||
239 | /* | |
240 | * Don't play with runt packets. | |
241 | */ | |
6aa20a22 | 242 | |
1da177e4 LT |
243 | if(isize<sizeof(struct iphdr)) |
244 | return isize; | |
6aa20a22 | 245 | |
1da177e4 LT |
246 | ip = (struct iphdr *) icp; |
247 | ||
248 | /* Bail if this packet isn't TCP, or is an IP fragment */ | |
249 | if (ip->protocol != IPPROTO_TCP || (ntohs(ip->frag_off) & 0x3fff)) { | |
250 | /* Send as regular IP */ | |
251 | if(ip->protocol != IPPROTO_TCP) | |
252 | comp->sls_o_nontcp++; | |
253 | else | |
254 | comp->sls_o_tcp++; | |
255 | return isize; | |
256 | } | |
257 | /* Extract TCP header */ | |
258 | ||
259 | th = (struct tcphdr *)(((unsigned char *)ip) + ip->ihl*4); | |
260 | hlen = ip->ihl*4 + th->doff*4; | |
261 | ||
262 | /* Bail if the TCP packet isn't `compressible' (i.e., ACK isn't set or | |
263 | * some other control bit is set). Also uncompressible if | |
264 | * it's a runt. | |
265 | */ | |
266 | if(hlen > isize || th->syn || th->fin || th->rst || | |
267 | ! (th->ack)){ | |
268 | /* TCP connection stuff; send as regular IP */ | |
269 | comp->sls_o_tcp++; | |
270 | return isize; | |
271 | } | |
272 | /* | |
273 | * Packet is compressible -- we're going to send either a | |
274 | * COMPRESSED_TCP or UNCOMPRESSED_TCP packet. Either way, | |
275 | * we need to locate (or create) the connection state. | |
276 | * | |
277 | * States are kept in a circularly linked list with | |
278 | * xmit_oldest pointing to the end of the list. The | |
279 | * list is kept in lru order by moving a state to the | |
280 | * head of the list whenever it is referenced. Since | |
281 | * the list is short and, empirically, the connection | |
282 | * we want is almost always near the front, we locate | |
283 | * states via linear search. If we don't find a state | |
284 | * for the datagram, the oldest state is (re-)used. | |
285 | */ | |
286 | for ( ; ; ) { | |
287 | if( ip->saddr == cs->cs_ip.saddr | |
288 | && ip->daddr == cs->cs_ip.daddr | |
289 | && th->source == cs->cs_tcp.source | |
290 | && th->dest == cs->cs_tcp.dest) | |
291 | goto found; | |
292 | ||
293 | /* if current equal oldest, at end of list */ | |
294 | if ( cs == ocs ) | |
295 | break; | |
296 | lcs = cs; | |
297 | cs = cs->next; | |
298 | comp->sls_o_searches++; | |
6403eab1 | 299 | } |
1da177e4 LT |
300 | /* |
301 | * Didn't find it -- re-use oldest cstate. Send an | |
302 | * uncompressed packet that tells the other side what | |
303 | * connection number we're using for this conversation. | |
304 | * | |
305 | * Note that since the state list is circular, the oldest | |
306 | * state points to the newest and we only need to set | |
307 | * xmit_oldest to update the lru linkage. | |
308 | */ | |
309 | comp->sls_o_misses++; | |
310 | comp->xmit_oldest = lcs->cs_this; | |
311 | goto uncompressed; | |
312 | ||
313 | found: | |
314 | /* | |
315 | * Found it -- move to the front on the connection list. | |
316 | */ | |
317 | if(lcs == ocs) { | |
318 | /* found at most recently used */ | |
319 | } else if (cs == ocs) { | |
320 | /* found at least recently used */ | |
321 | comp->xmit_oldest = lcs->cs_this; | |
322 | } else { | |
323 | /* more than 2 elements */ | |
324 | lcs->next = cs->next; | |
325 | cs->next = ocs->next; | |
326 | ocs->next = cs; | |
327 | } | |
328 | ||
329 | /* | |
330 | * Make sure that only what we expect to change changed. | |
331 | * Check the following: | |
332 | * IP protocol version, header length & type of service. | |
333 | * The "Don't fragment" bit. | |
334 | * The time-to-live field. | |
335 | * The TCP header length. | |
336 | * IP options, if any. | |
337 | * TCP options, if any. | |
338 | * If any of these things are different between the previous & | |
339 | * current datagram, we send the current datagram `uncompressed'. | |
340 | */ | |
341 | oth = &cs->cs_tcp; | |
342 | ||
343 | if(ip->version != cs->cs_ip.version || ip->ihl != cs->cs_ip.ihl | |
344 | || ip->tos != cs->cs_ip.tos | |
345 | || (ip->frag_off & htons(0x4000)) != (cs->cs_ip.frag_off & htons(0x4000)) | |
346 | || ip->ttl != cs->cs_ip.ttl | |
347 | || th->doff != cs->cs_tcp.doff | |
348 | || (ip->ihl > 5 && memcmp(ip+1,cs->cs_ipopt,((ip->ihl)-5)*4) != 0) | |
349 | || (th->doff > 5 && memcmp(th+1,cs->cs_tcpopt,((th->doff)-5)*4) != 0)){ | |
350 | goto uncompressed; | |
351 | } | |
352 | ||
353 | /* | |
354 | * Figure out which of the changing fields changed. The | |
355 | * receiver expects changes in the order: urgent, window, | |
356 | * ack, seq (the order minimizes the number of temporaries | |
357 | * needed in this section of code). | |
358 | */ | |
359 | if(th->urg){ | |
360 | deltaS = ntohs(th->urg_ptr); | |
361 | cp = encode(cp,deltaS); | |
362 | changes |= NEW_U; | |
363 | } else if(th->urg_ptr != oth->urg_ptr){ | |
364 | /* argh! URG not set but urp changed -- a sensible | |
365 | * implementation should never do this but RFC793 | |
366 | * doesn't prohibit the change so we have to deal | |
367 | * with it. */ | |
368 | goto uncompressed; | |
369 | } | |
370 | if((deltaS = ntohs(th->window) - ntohs(oth->window)) != 0){ | |
371 | cp = encode(cp,deltaS); | |
372 | changes |= NEW_W; | |
373 | } | |
374 | if((deltaA = ntohl(th->ack_seq) - ntohl(oth->ack_seq)) != 0L){ | |
375 | if(deltaA > 0x0000ffff) | |
376 | goto uncompressed; | |
377 | cp = encode(cp,deltaA); | |
378 | changes |= NEW_A; | |
379 | } | |
380 | if((deltaS = ntohl(th->seq) - ntohl(oth->seq)) != 0L){ | |
381 | if(deltaS > 0x0000ffff) | |
382 | goto uncompressed; | |
383 | cp = encode(cp,deltaS); | |
384 | changes |= NEW_S; | |
385 | } | |
386 | ||
387 | switch(changes){ | |
388 | case 0: /* Nothing changed. If this packet contains data and the | |
389 | * last one didn't, this is probably a data packet following | |
390 | * an ack (normal on an interactive connection) and we send | |
391 | * it compressed. Otherwise it's probably a retransmit, | |
392 | * retransmitted ack or window probe. Send it uncompressed | |
393 | * in case the other side missed the compressed version. | |
394 | */ | |
395 | if(ip->tot_len != cs->cs_ip.tot_len && | |
396 | ntohs(cs->cs_ip.tot_len) == hlen) | |
397 | break; | |
398 | goto uncompressed; | |
1da177e4 LT |
399 | case SPECIAL_I: |
400 | case SPECIAL_D: | |
401 | /* actual changes match one of our special case encodings -- | |
402 | * send packet uncompressed. | |
403 | */ | |
404 | goto uncompressed; | |
405 | case NEW_S|NEW_A: | |
406 | if(deltaS == deltaA && | |
407 | deltaS == ntohs(cs->cs_ip.tot_len) - hlen){ | |
408 | /* special case for echoed terminal traffic */ | |
409 | changes = SPECIAL_I; | |
410 | cp = new_seq; | |
411 | } | |
412 | break; | |
413 | case NEW_S: | |
414 | if(deltaS == ntohs(cs->cs_ip.tot_len) - hlen){ | |
415 | /* special case for data xfer */ | |
416 | changes = SPECIAL_D; | |
417 | cp = new_seq; | |
418 | } | |
419 | break; | |
420 | } | |
421 | deltaS = ntohs(ip->id) - ntohs(cs->cs_ip.id); | |
422 | if(deltaS != 1){ | |
423 | cp = encode(cp,deltaS); | |
424 | changes |= NEW_I; | |
425 | } | |
426 | if(th->psh) | |
427 | changes |= TCP_PUSH_BIT; | |
428 | /* Grab the cksum before we overwrite it below. Then update our | |
429 | * state with this packet's header. | |
430 | */ | |
7cd61888 | 431 | csum = th->check; |
1da177e4 LT |
432 | memcpy(&cs->cs_ip,ip,20); |
433 | memcpy(&cs->cs_tcp,th,20); | |
434 | /* We want to use the original packet as our compressed packet. | |
435 | * (cp - new_seq) is the number of bytes we need for compressed | |
436 | * sequence numbers. In addition we need one byte for the change | |
437 | * mask, one for the connection id and two for the tcp checksum. | |
438 | * So, (cp - new_seq) + 4 bytes of header are needed. | |
439 | */ | |
440 | deltaS = cp - new_seq; | |
441 | if(compress_cid == 0 || comp->xmit_current != cs->cs_this){ | |
442 | cp = ocp; | |
443 | *cpp = ocp; | |
444 | *cp++ = changes | NEW_C; | |
445 | *cp++ = cs->cs_this; | |
446 | comp->xmit_current = cs->cs_this; | |
447 | } else { | |
448 | cp = ocp; | |
449 | *cpp = ocp; | |
450 | *cp++ = changes; | |
451 | } | |
7cd61888 AV |
452 | *(__sum16 *)cp = csum; |
453 | cp += 2; | |
1da177e4 LT |
454 | /* deltaS is now the size of the change section of the compressed header */ |
455 | memcpy(cp,new_seq,deltaS); /* Write list of deltas */ | |
456 | memcpy(cp+deltaS,icp+hlen,isize-hlen); | |
457 | comp->sls_o_compressed++; | |
458 | ocp[0] |= SL_TYPE_COMPRESSED_TCP; | |
459 | return isize - hlen + deltaS + (cp - ocp); | |
460 | ||
461 | /* Update connection state cs & send uncompressed packet (i.e., | |
462 | * a regular ip/tcp packet but with the 'conversation id' we hope | |
463 | * to use on future compressed packets in the protocol field). | |
464 | */ | |
465 | uncompressed: | |
466 | memcpy(&cs->cs_ip,ip,20); | |
467 | memcpy(&cs->cs_tcp,th,20); | |
468 | if (ip->ihl > 5) | |
469 | memcpy(cs->cs_ipopt, ip+1, ((ip->ihl) - 5) * 4); | |
470 | if (th->doff > 5) | |
471 | memcpy(cs->cs_tcpopt, th+1, ((th->doff) - 5) * 4); | |
472 | comp->xmit_current = cs->cs_this; | |
473 | comp->sls_o_uncompressed++; | |
474 | memcpy(ocp, icp, isize); | |
475 | *cpp = ocp; | |
476 | ocp[9] = cs->cs_this; | |
477 | ocp[0] |= SL_TYPE_UNCOMPRESSED_TCP; | |
478 | return isize; | |
479 | } | |
480 | ||
481 | ||
482 | int | |
483 | slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize) | |
484 | { | |
485 | register int changes; | |
486 | long x; | |
487 | register struct tcphdr *thp; | |
488 | register struct iphdr *ip; | |
489 | register struct cstate *cs; | |
490 | int len, hdrlen; | |
491 | unsigned char *cp = icp; | |
492 | ||
493 | /* We've got a compressed packet; read the change byte */ | |
494 | comp->sls_i_compressed++; | |
495 | if(isize < 3){ | |
496 | comp->sls_i_error++; | |
497 | return 0; | |
498 | } | |
499 | changes = *cp++; | |
500 | if(changes & NEW_C){ | |
501 | /* Make sure the state index is in range, then grab the state. | |
502 | * If we have a good state index, clear the 'discard' flag. | |
503 | */ | |
504 | x = *cp++; /* Read conn index */ | |
505 | if(x < 0 || x > comp->rslot_limit) | |
506 | goto bad; | |
507 | ||
508 | comp->flags &=~ SLF_TOSS; | |
509 | comp->recv_current = x; | |
510 | } else { | |
511 | /* this packet has an implicit state index. If we've | |
512 | * had a line error since the last time we got an | |
513 | * explicit state index, we have to toss the packet. */ | |
514 | if(comp->flags & SLF_TOSS){ | |
515 | comp->sls_i_tossed++; | |
516 | return 0; | |
517 | } | |
518 | } | |
519 | cs = &comp->rstate[comp->recv_current]; | |
520 | thp = &cs->cs_tcp; | |
521 | ip = &cs->cs_ip; | |
522 | ||
7cd61888 AV |
523 | thp->check = *(__sum16 *)cp; |
524 | cp += 2; | |
1da177e4 LT |
525 | |
526 | thp->psh = (changes & TCP_PUSH_BIT) ? 1 : 0; | |
527 | /* | |
528 | * we can use the same number for the length of the saved header and | |
529 | * the current one, because the packet wouldn't have been sent | |
530 | * as compressed unless the options were the same as the previous one | |
531 | */ | |
532 | ||
533 | hdrlen = ip->ihl * 4 + thp->doff * 4; | |
534 | ||
535 | switch(changes & SPECIALS_MASK){ | |
536 | case SPECIAL_I: /* Echoed terminal traffic */ | |
537 | { | |
538 | register short i; | |
539 | i = ntohs(ip->tot_len) - hdrlen; | |
540 | thp->ack_seq = htonl( ntohl(thp->ack_seq) + i); | |
541 | thp->seq = htonl( ntohl(thp->seq) + i); | |
542 | } | |
543 | break; | |
544 | ||
545 | case SPECIAL_D: /* Unidirectional data */ | |
546 | thp->seq = htonl( ntohl(thp->seq) + | |
547 | ntohs(ip->tot_len) - hdrlen); | |
548 | break; | |
549 | ||
550 | default: | |
551 | if(changes & NEW_U){ | |
552 | thp->urg = 1; | |
553 | if((x = decode(&cp)) == -1) { | |
554 | goto bad; | |
555 | } | |
556 | thp->urg_ptr = htons(x); | |
557 | } else | |
558 | thp->urg = 0; | |
559 | if(changes & NEW_W){ | |
560 | if((x = decode(&cp)) == -1) { | |
561 | goto bad; | |
562 | } | |
563 | thp->window = htons( ntohs(thp->window) + x); | |
564 | } | |
565 | if(changes & NEW_A){ | |
566 | if((x = decode(&cp)) == -1) { | |
567 | goto bad; | |
568 | } | |
569 | thp->ack_seq = htonl( ntohl(thp->ack_seq) + x); | |
570 | } | |
571 | if(changes & NEW_S){ | |
572 | if((x = decode(&cp)) == -1) { | |
573 | goto bad; | |
574 | } | |
575 | thp->seq = htonl( ntohl(thp->seq) + x); | |
576 | } | |
577 | break; | |
578 | } | |
579 | if(changes & NEW_I){ | |
580 | if((x = decode(&cp)) == -1) { | |
581 | goto bad; | |
582 | } | |
583 | ip->id = htons (ntohs (ip->id) + x); | |
584 | } else | |
585 | ip->id = htons (ntohs (ip->id) + 1); | |
586 | ||
587 | /* | |
588 | * At this point, cp points to the first byte of data in the | |
589 | * packet. Put the reconstructed TCP and IP headers back on the | |
590 | * packet. Recalculate IP checksum (but not TCP checksum). | |
591 | */ | |
592 | ||
593 | len = isize - (cp - icp); | |
594 | if (len < 0) | |
595 | goto bad; | |
596 | len += hdrlen; | |
597 | ip->tot_len = htons(len); | |
598 | ip->check = 0; | |
599 | ||
600 | memmove(icp + hdrlen, cp, len - hdrlen); | |
601 | ||
602 | cp = icp; | |
603 | memcpy(cp, ip, 20); | |
604 | cp += 20; | |
605 | ||
606 | if (ip->ihl > 5) { | |
607 | memcpy(cp, cs->cs_ipopt, (ip->ihl - 5) * 4); | |
608 | cp += (ip->ihl - 5) * 4; | |
609 | } | |
610 | ||
611 | put_unaligned(ip_fast_csum(icp, ip->ihl), | |
612 | &((struct iphdr *)icp)->check); | |
613 | ||
614 | memcpy(cp, thp, 20); | |
615 | cp += 20; | |
616 | ||
617 | if (thp->doff > 5) { | |
618 | memcpy(cp, cs->cs_tcpopt, ((thp->doff) - 5) * 4); | |
619 | cp += ((thp->doff) - 5) * 4; | |
620 | } | |
621 | ||
622 | return len; | |
623 | bad: | |
624 | comp->sls_i_error++; | |
625 | return slhc_toss( comp ); | |
626 | } | |
627 | ||
628 | ||
629 | int | |
630 | slhc_remember(struct slcompress *comp, unsigned char *icp, int isize) | |
631 | { | |
632 | register struct cstate *cs; | |
633 | unsigned ihl; | |
634 | ||
635 | unsigned char index; | |
636 | ||
637 | if(isize < 20) { | |
638 | /* The packet is shorter than a legal IP header */ | |
639 | comp->sls_i_runt++; | |
640 | return slhc_toss( comp ); | |
641 | } | |
642 | /* Peek at the IP header's IHL field to find its length */ | |
643 | ihl = icp[0] & 0xf; | |
644 | if(ihl < 20 / 4){ | |
645 | /* The IP header length field is too small */ | |
646 | comp->sls_i_runt++; | |
647 | return slhc_toss( comp ); | |
648 | } | |
649 | index = icp[9]; | |
650 | icp[9] = IPPROTO_TCP; | |
651 | ||
652 | if (ip_fast_csum(icp, ihl)) { | |
653 | /* Bad IP header checksum; discard */ | |
654 | comp->sls_i_badcheck++; | |
655 | return slhc_toss( comp ); | |
656 | } | |
657 | if(index > comp->rslot_limit) { | |
658 | comp->sls_i_error++; | |
659 | return slhc_toss(comp); | |
660 | } | |
661 | ||
662 | /* Update local state */ | |
663 | cs = &comp->rstate[comp->recv_current = index]; | |
664 | comp->flags &=~ SLF_TOSS; | |
665 | memcpy(&cs->cs_ip,icp,20); | |
666 | memcpy(&cs->cs_tcp,icp + ihl*4,20); | |
667 | if (ihl > 5) | |
668 | memcpy(cs->cs_ipopt, icp + sizeof(struct iphdr), (ihl - 5) * 4); | |
669 | if (cs->cs_tcp.doff > 5) | |
670 | memcpy(cs->cs_tcpopt, icp + ihl*4 + sizeof(struct tcphdr), (cs->cs_tcp.doff - 5) * 4); | |
671 | cs->cs_hsize = ihl*2 + cs->cs_tcp.doff*2; | |
672 | /* Put headers back on packet | |
673 | * Neither header checksum is recalculated | |
674 | */ | |
675 | comp->sls_i_uncompressed++; | |
676 | return isize; | |
677 | } | |
678 | ||
679 | int | |
680 | slhc_toss(struct slcompress *comp) | |
681 | { | |
682 | if ( comp == NULLSLCOMPR ) | |
683 | return 0; | |
684 | ||
685 | comp->flags |= SLF_TOSS; | |
686 | return 0; | |
687 | } | |
688 | ||
1da177e4 LT |
689 | #else /* CONFIG_INET */ |
690 | ||
1da177e4 LT |
691 | int |
692 | slhc_toss(struct slcompress *comp) | |
693 | { | |
694 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_toss"); | |
695 | return -EINVAL; | |
696 | } | |
697 | int | |
698 | slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize) | |
699 | { | |
700 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_uncompress"); | |
701 | return -EINVAL; | |
702 | } | |
703 | int | |
704 | slhc_compress(struct slcompress *comp, unsigned char *icp, int isize, | |
705 | unsigned char *ocp, unsigned char **cpp, int compress_cid) | |
706 | { | |
707 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_compress"); | |
708 | return -EINVAL; | |
709 | } | |
710 | ||
711 | int | |
712 | slhc_remember(struct slcompress *comp, unsigned char *icp, int isize) | |
713 | { | |
714 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_remember"); | |
715 | return -EINVAL; | |
716 | } | |
717 | ||
718 | void | |
719 | slhc_free(struct slcompress *comp) | |
720 | { | |
721 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_free"); | |
1da177e4 LT |
722 | } |
723 | struct slcompress * | |
724 | slhc_init(int rslots, int tslots) | |
725 | { | |
726 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_init"); | |
727 | return NULL; | |
728 | } | |
7f8a688e DK |
729 | |
730 | #endif /* CONFIG_INET */ | |
731 | ||
732 | /* VJ header compression */ | |
1da177e4 LT |
733 | EXPORT_SYMBOL(slhc_init); |
734 | EXPORT_SYMBOL(slhc_free); | |
735 | EXPORT_SYMBOL(slhc_remember); | |
736 | EXPORT_SYMBOL(slhc_compress); | |
737 | EXPORT_SYMBOL(slhc_uncompress); | |
738 | EXPORT_SYMBOL(slhc_toss); | |
739 | ||
1da177e4 | 740 | MODULE_LICENSE("Dual BSD/GPL"); |