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 <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 | /* 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 | */ |
91 | struct slcompress * |
92 | slhc_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(error: -EINVAL); |
100 | |
101 | comp = kzalloc(size: 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(size: 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(size: 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 | |
143 | out_free2: |
144 | kfree(objp: comp->rstate); |
145 | out_free: |
146 | kfree(objp: comp); |
147 | out_fail: |
148 | return ERR_PTR(error: -ENOMEM); |
149 | } |
150 | |
151 | |
152 | /* Free a compression data structure */ |
153 | void |
154 | slhc_free(struct slcompress *comp) |
155 | { |
156 | if ( IS_ERR_OR_NULL(ptr: comp) ) |
157 | return; |
158 | |
159 | if ( comp->tstate != NULLSLSTATE ) |
160 | kfree( objp: comp->tstate ); |
161 | |
162 | if ( comp->rstate != NULLSLSTATE ) |
163 | kfree( objp: comp->rstate ); |
164 | |
165 | kfree( objp: comp ); |
166 | } |
167 | |
168 | |
169 | /* Put a short in host order into a char array in network order */ |
170 | static inline unsigned char * |
171 | put16(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 */ |
181 | static unsigned char * |
182 | encode(unsigned char *cp, unsigned short n) |
183 | { |
184 | if(n >= 256 || n == 0){ |
185 | *cp++ = 0; |
186 | cp = put16(cp,x: 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 */ |
194 | static unsigned short |
195 | pull16(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 */ |
206 | static long |
207 | decode(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 | |
226 | int |
227 | slhc_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 | |
323 | found: |
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(p: ip+1,q: cs->cs_ipopt,size: ((ip->ihl)-5)*4) != 0) |
359 | || (th->doff > 5 && memcmp(p: th+1,q: cs->cs_tcpopt,size: ((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,n: 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,n: 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,n: 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,n: 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,n: 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 | */ |
475 | uncompressed: |
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 | |
492 | int |
493 | slhc_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(cpp: &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(cpp: &cp)) == -1) { |
575 | goto bad; |
576 | } |
577 | thp->window = htons( ntohs(thp->window) + x); |
578 | } |
579 | if(changes & NEW_A){ |
580 | if((x = decode(cpp: &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(cpp: &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(cpp: &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; |
637 | bad: |
638 | comp->sls_i_error++; |
639 | return slhc_toss( comp ); |
640 | } |
641 | |
642 | |
643 | int |
644 | slhc_remember(struct slcompress *comp, unsigned char *icp, int isize) |
645 | { |
646 | struct cstate *cs; |
647 | unsigned ihl; |
648 | |
649 | unsigned char index; |
650 | |
651 | if(isize < 20) { |
652 | /* The packet is shorter than a legal IP header */ |
653 | comp->sls_i_runt++; |
654 | return slhc_toss( comp ); |
655 | } |
656 | /* Peek at the IP header's IHL field to find its length */ |
657 | ihl = icp[0] & 0xf; |
658 | if(ihl < 20 / 4){ |
659 | /* The IP header length field is too small */ |
660 | comp->sls_i_runt++; |
661 | return slhc_toss( comp ); |
662 | } |
663 | index = icp[9]; |
664 | icp[9] = IPPROTO_TCP; |
665 | |
666 | if (ip_fast_csum(iph: icp, ihl)) { |
667 | /* Bad IP header checksum; discard */ |
668 | comp->sls_i_badcheck++; |
669 | return slhc_toss( comp ); |
670 | } |
671 | if(index > comp->rslot_limit) { |
672 | comp->sls_i_error++; |
673 | return slhc_toss(comp); |
674 | } |
675 | |
676 | /* Update local state */ |
677 | cs = &comp->rstate[comp->recv_current = index]; |
678 | comp->flags &=~ SLF_TOSS; |
679 | memcpy(&cs->cs_ip,icp,20); |
680 | memcpy(&cs->cs_tcp,icp + ihl*4,20); |
681 | if (ihl > 5) |
682 | memcpy(cs->cs_ipopt, icp + sizeof(struct iphdr), (ihl - 5) * 4); |
683 | if (cs->cs_tcp.doff > 5) |
684 | memcpy(cs->cs_tcpopt, icp + ihl*4 + sizeof(struct tcphdr), (cs->cs_tcp.doff - 5) * 4); |
685 | cs->cs_hsize = ihl*2 + cs->cs_tcp.doff*2; |
686 | cs->initialized = true; |
687 | /* Put headers back on packet |
688 | * Neither header checksum is recalculated |
689 | */ |
690 | comp->sls_i_uncompressed++; |
691 | return isize; |
692 | } |
693 | |
694 | int |
695 | slhc_toss(struct slcompress *comp) |
696 | { |
697 | if ( comp == NULLSLCOMPR ) |
698 | return 0; |
699 | |
700 | comp->flags |= SLF_TOSS; |
701 | return 0; |
702 | } |
703 | |
704 | #else /* CONFIG_INET */ |
705 | |
706 | int |
707 | slhc_toss(struct slcompress *comp) |
708 | { |
709 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_toss" ); |
710 | return -EINVAL; |
711 | } |
712 | int |
713 | slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize) |
714 | { |
715 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_uncompress" ); |
716 | return -EINVAL; |
717 | } |
718 | int |
719 | slhc_compress(struct slcompress *comp, unsigned char *icp, int isize, |
720 | unsigned char *ocp, unsigned char **cpp, int compress_cid) |
721 | { |
722 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_compress" ); |
723 | return -EINVAL; |
724 | } |
725 | |
726 | int |
727 | slhc_remember(struct slcompress *comp, unsigned char *icp, int isize) |
728 | { |
729 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_remember" ); |
730 | return -EINVAL; |
731 | } |
732 | |
733 | void |
734 | slhc_free(struct slcompress *comp) |
735 | { |
736 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_free" ); |
737 | } |
738 | struct slcompress * |
739 | slhc_init(int rslots, int tslots) |
740 | { |
741 | printk(KERN_DEBUG "Called IP function on non IP-system: slhc_init" ); |
742 | return NULL; |
743 | } |
744 | |
745 | #endif /* CONFIG_INET */ |
746 | |
747 | /* VJ header compression */ |
748 | EXPORT_SYMBOL(slhc_init); |
749 | EXPORT_SYMBOL(slhc_free); |
750 | EXPORT_SYMBOL(slhc_remember); |
751 | EXPORT_SYMBOL(slhc_compress); |
752 | EXPORT_SYMBOL(slhc_uncompress); |
753 | EXPORT_SYMBOL(slhc_toss); |
754 | |
755 | MODULE_LICENSE("Dual BSD/GPL" ); |
756 | |