1/* 2 * BSD compression module 3 * 4 * Patched version for ISDN syncPPP written 1997/1998 by Michael Hipp 5 * The whole module is now SKB based. 6 * 7 */ 8 9/* 10 * Update: The Berkeley copyright was changed, and the change 11 * is retroactive to all "true" BSD software (ie everything 12 * from UCB as opposed to other peoples code that just carried 13 * the same license). The new copyright doesn't clash with the 14 * GPL, so the module-only restriction has been removed.. 15 */ 16 17/* 18 * Original copyright notice: 19 * 20 * Copyright (c) 1985, 1986 The Regents of the University of California. 21 * All rights reserved. 22 * 23 * This code is derived from software contributed to Berkeley by 24 * James A. Woods, derived from original work by Spencer Thomas 25 * and Joseph Orost. 26 * 27 * Redistribution and use in source and binary forms, with or without 28 * modification, are permitted provided that the following conditions 29 * are met: 30 * 1. Redistributions of source code must retain the above copyright 31 * notice, this list of conditions and the following disclaimer. 32 * 2. Redistributions in binary form must reproduce the above copyright 33 * notice, this list of conditions and the following disclaimer in the 34 * documentation and/or other materials provided with the distribution. 35 * 3. All advertising materials mentioning features or use of this software 36 * must display the following acknowledgement: 37 * This product includes software developed by the University of 38 * California, Berkeley and its contributors. 39 * 4. Neither the name of the University nor the names of its contributors 40 * may be used to endorse or promote products derived from this software 41 * without specific prior written permission. 42 * 43 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 44 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 45 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 46 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 47 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 48 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 49 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 50 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 51 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 52 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 53 * SUCH DAMAGE. 54 */ 55 56#include <linux/module.h> 57#include <linux/init.h> 58#include <linux/kernel.h> 59#include <linux/types.h> 60#include <linux/fcntl.h> 61#include <linux/interrupt.h> 62#include <linux/ptrace.h> 63#include <linux/ioport.h> 64#include <linux/in.h> 65#include <linux/slab.h> 66#include <linux/tty.h> 67#include <linux/errno.h> 68#include <linux/string.h> /* used in new tty drivers */ 69#include <linux/signal.h> /* used in new tty drivers */ 70#include <linux/bitops.h> 71 72#include <asm/system.h> 73#include <asm/byteorder.h> 74#include <asm/types.h> 75 76#include <linux/if.h> 77 78#include <linux/if_ether.h> 79#include <linux/netdevice.h> 80#include <linux/skbuff.h> 81#include <linux/inet.h> 82#include <linux/ioctl.h> 83#include <linux/vmalloc.h> 84 85#include <linux/ppp_defs.h> 86 87#include <linux/isdn.h> 88#include <linux/isdn_ppp.h> 89#include <linux/ip.h> 90#include <linux/tcp.h> 91#include <linux/if_arp.h> 92#include <linux/ppp-comp.h> 93 94#include "isdn_ppp.h" 95 96MODULE_DESCRIPTION("ISDN4Linux: BSD Compression for PPP over ISDN"); 97MODULE_LICENSE("Dual BSD/GPL"); 98 99#define BSD_VERSION(x) ((x) >> 5) 100#define BSD_NBITS(x) ((x) & 0x1F) 101 102#define BSD_CURRENT_VERSION 1 103 104#define DEBUG 1 105 106/* 107 * A dictionary for doing BSD compress. 108 */ 109 110struct bsd_dict { 111 u32 fcode; 112 u16 codem1; /* output of hash table -1 */ 113 u16 cptr; /* map code to hash table entry */ 114}; 115 116struct bsd_db { 117 int totlen; /* length of this structure */ 118 unsigned int hsize; /* size of the hash table */ 119 unsigned char hshift; /* used in hash function */ 120 unsigned char n_bits; /* current bits/code */ 121 unsigned char maxbits; /* maximum bits/code */ 122 unsigned char debug; /* non-zero if debug desired */ 123 unsigned char unit; /* ppp unit number */ 124 u16 seqno; /* sequence # of next packet */ 125 unsigned int mru; /* size of receive (decompress) bufr */ 126 unsigned int maxmaxcode; /* largest valid code */ 127 unsigned int max_ent; /* largest code in use */ 128 unsigned int in_count; /* uncompressed bytes, aged */ 129 unsigned int bytes_out; /* compressed bytes, aged */ 130 unsigned int ratio; /* recent compression ratio */ 131 unsigned int checkpoint; /* when to next check the ratio */ 132 unsigned int clear_count; /* times dictionary cleared */ 133 unsigned int incomp_count; /* incompressible packets */ 134 unsigned int incomp_bytes; /* incompressible bytes */ 135 unsigned int uncomp_count; /* uncompressed packets */ 136 unsigned int uncomp_bytes; /* uncompressed bytes */ 137 unsigned int comp_count; /* compressed packets */ 138 unsigned int comp_bytes; /* compressed bytes */ 139 unsigned short *lens; /* array of lengths of codes */ 140 struct bsd_dict *dict; /* dictionary */ 141 int xmit; 142}; 143 144#define BSD_OVHD 2 /* BSD compress overhead/packet */ 145#define MIN_BSD_BITS 9 146#define BSD_INIT_BITS MIN_BSD_BITS 147#define MAX_BSD_BITS 15 148 149/* 150 * the next two codes should not be changed lightly, as they must not 151 * lie within the contiguous general code space. 152 */ 153#define CLEAR 256 /* table clear output code */ 154#define FIRST 257 /* first free entry */ 155#define LAST 255 156 157#define MAXCODE(b) ((1 << (b)) - 1) 158#define BADCODEM1 MAXCODE(MAX_BSD_BITS); 159 160#define BSD_HASH(prefix,suffix,hshift) ((((unsigned long)(suffix))<<(hshift)) \ 161 ^ (unsigned long)(prefix)) 162#define BSD_KEY(prefix,suffix) ((((unsigned long)(suffix)) << 16) \ 163 + (unsigned long)(prefix)) 164 165#define CHECK_GAP 10000 /* Ratio check interval */ 166 167#define RATIO_SCALE_LOG 8 168#define RATIO_SCALE (1<<RATIO_SCALE_LOG) 169#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) 170 171/* 172 * clear the dictionary 173 */ 174 175static void bsd_clear(struct bsd_db *db) 176{ 177 db->clear_count++; 178 db->max_ent = FIRST-1; 179 db->n_bits = BSD_INIT_BITS; 180 db->bytes_out = 0; 181 db->in_count = 0; 182 db->incomp_count = 0; 183 db->ratio = 0; 184 db->checkpoint = CHECK_GAP; 185} 186 187/* 188 * If the dictionary is full, then see if it is time to reset it. 189 * 190 * Compute the compression ratio using fixed-point arithmetic 191 * with 8 fractional bits. 192 * 193 * Since we have an infinite stream instead of a single file, 194 * watch only the local compression ratio. 195 * 196 * Since both peers must reset the dictionary at the same time even in 197 * the absence of CLEAR codes (while packets are incompressible), they 198 * must compute the same ratio. 199 */ 200static int bsd_check (struct bsd_db *db) /* 1=output CLEAR */ 201{ 202 unsigned int new_ratio; 203 204 if (db->in_count >= db->checkpoint) 205 { 206 /* age the ratio by limiting the size of the counts */ 207 if (db->in_count >= RATIO_MAX || db->bytes_out >= RATIO_MAX) 208 { 209 db->in_count -= (db->in_count >> 2); 210 db->bytes_out -= (db->bytes_out >> 2); 211 } 212 213 db->checkpoint = db->in_count + CHECK_GAP; 214 215 if (db->max_ent >= db->maxmaxcode) 216 { 217 /* Reset the dictionary only if the ratio is worse, 218 * or if it looks as if it has been poisoned 219 * by incompressible data. 220 * 221 * This does not overflow, because 222 * db->in_count <= RATIO_MAX. 223 */ 224 225 new_ratio = db->in_count << RATIO_SCALE_LOG; 226 if (db->bytes_out != 0) 227 { 228 new_ratio /= db->bytes_out; 229 } 230 231 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) 232 { 233 bsd_clear (db); 234 return 1; 235 } 236 db->ratio = new_ratio; 237 } 238 } 239 return 0; 240} 241 242/* 243 * Return statistics. 244 */ 245 246static void bsd_stats (void *state, struct compstat *stats) 247{ 248 struct bsd_db *db = (struct bsd_db *) state; 249 250 stats->unc_bytes = db->uncomp_bytes; 251 stats->unc_packets = db->uncomp_count; 252 stats->comp_bytes = db->comp_bytes; 253 stats->comp_packets = db->comp_count; 254 stats->inc_bytes = db->incomp_bytes; 255 stats->inc_packets = db->incomp_count; 256 stats->in_count = db->in_count; 257 stats->bytes_out = db->bytes_out; 258} 259 260/* 261 * Reset state, as on a CCP ResetReq. 262 */ 263static void bsd_reset (void *state,unsigned char code, unsigned char id, 264 unsigned char *data, unsigned len, 265 struct isdn_ppp_resetparams *rsparm) 266{ 267 struct bsd_db *db = (struct bsd_db *) state; 268 269 bsd_clear(db); 270 db->seqno = 0; 271 db->clear_count = 0; 272} 273 274/* 275 * Release the compression structure 276 */ 277static void bsd_free (void *state) 278{ 279 struct bsd_db *db = (struct bsd_db *) state; 280 281 if (db) { 282 /* 283 * Release the dictionary 284 */ 285 vfree(db->dict); 286 db->dict = NULL; 287 288 /* 289 * Release the string buffer 290 */ 291 vfree(db->lens); 292 db->lens = NULL; 293 294 /* 295 * Finally release the structure itself. 296 */ 297 kfree(db); 298 } 299} 300 301 302/* 303 * Allocate space for a (de) compressor. 304 */ 305static void *bsd_alloc (struct isdn_ppp_comp_data *data) 306{ 307 int bits; 308 unsigned int hsize, hshift, maxmaxcode; 309 struct bsd_db *db; 310 int decomp; 311 312 static unsigned int htab[][2] = { 313 { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } , 314 { 9001 , 5 } , { 18013 , 6 } , { 35023 , 7 } , { 69001 , 8 } 315 }; 316 317 if (data->optlen != 1 || data->num != CI_BSD_COMPRESS 318 || BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION) 319 return NULL; 320 321 bits = BSD_NBITS(data->options[0]); 322 323 if(bits < 9 || bits > 15) 324 return NULL; 325 326 hsize = htab[bits-9][0]; 327 hshift = htab[bits-9][1]; 328 329 /* 330 * Allocate the main control structure for this instance. 331 */ 332 maxmaxcode = MAXCODE(bits); 333 db = kzalloc (sizeof (struct bsd_db),GFP_KERNEL); 334 if (!db) 335 return NULL; 336 337 db->xmit = data->flags & IPPP_COMP_FLAG_XMIT; 338 decomp = db->xmit ? 0 : 1; 339 340 /* 341 * Allocate space for the dictionary. This may be more than one page in 342 * length. 343 */ 344 db->dict = vmalloc(hsize * sizeof(struct bsd_dict)); 345 if (!db->dict) { 346 bsd_free (db); 347 return NULL; 348 } 349 350 /* 351 * If this is the compression buffer then there is no length data. 352 * For decompression, the length information is needed as well. 353 */ 354 if (!decomp) 355 db->lens = NULL; 356 else { 357 db->lens = vmalloc((maxmaxcode + 1) * sizeof(db->lens[0])); 358 if (!db->lens) { 359 bsd_free (db); 360 return (NULL); 361 } 362 } 363 364 /* 365 * Initialize the data information for the compression code 366 */ 367 db->totlen = sizeof (struct bsd_db) + (sizeof (struct bsd_dict) * hsize); 368 db->hsize = hsize; 369 db->hshift = hshift; 370 db->maxmaxcode = maxmaxcode; 371 db->maxbits = bits; 372 373 return (void *) db; 374} 375 376/* 377 * Initialize the database. 378 */ 379static int bsd_init (void *state, struct isdn_ppp_comp_data *data, int unit, int debug) 380{ 381 struct bsd_db *db = state; 382 int indx; 383 int decomp; 384 385 if(!state || !data) { 386 printk(KERN_ERR "isdn_bsd_init: [%d] ERR, state %lx data %lx\n",unit,(long)state,(long)data); 387 return 0; 388 } 389 390 decomp = db->xmit ? 0 : 1; 391 392 if (data->optlen != 1 || data->num != CI_BSD_COMPRESS 393 || (BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION) 394 || (BSD_NBITS(data->options[0]) != db->maxbits) 395 || (decomp && db->lens == NULL)) { 396 printk(KERN_ERR "isdn_bsd: %d %d %d %d %lx\n",data->optlen,data->num,data->options[0],decomp,(unsigned long)db->lens); 397 return 0; 398 } 399 400 if (decomp) 401 for(indx=LAST;indx>=0;indx--) 402 db->lens[indx] = 1; 403 404 indx = db->hsize; 405 while (indx-- != 0) { 406 db->dict[indx].codem1 = BADCODEM1; 407 db->dict[indx].cptr = 0; 408 } 409 410 db->unit = unit; 411 db->mru = 0; 412 413 db->debug = 1; 414 415 bsd_reset(db,0,0,NULL,0,NULL); 416 417 return 1; 418} 419 420/* 421 * Obtain pointers to the various structures in the compression tables 422 */ 423 424#define dict_ptrx(p,idx) &(p->dict[idx]) 425#define lens_ptrx(p,idx) &(p->lens[idx]) 426 427#ifdef DEBUG 428static unsigned short *lens_ptr(struct bsd_db *db, int idx) 429{ 430 if ((unsigned int) idx > (unsigned int) db->maxmaxcode) { 431 printk (KERN_DEBUG "<9>ppp: lens_ptr(%d) > max\n", idx); 432 idx = 0; 433 } 434 return lens_ptrx (db, idx); 435} 436 437static struct bsd_dict *dict_ptr(struct bsd_db *db, int idx) 438{ 439 if ((unsigned int) idx >= (unsigned int) db->hsize) { 440 printk (KERN_DEBUG "<9>ppp: dict_ptr(%d) > max\n", idx); 441 idx = 0; 442 } 443 return dict_ptrx (db, idx); 444} 445 446#else 447#define lens_ptr(db,idx) lens_ptrx(db,idx) 448#define dict_ptr(db,idx) dict_ptrx(db,idx) 449#endif 450 451/* 452 * compress a packet 453 */ 454static int bsd_compress (void *state, struct sk_buff *skb_in, struct sk_buff *skb_out,int proto) 455{ 456 struct bsd_db *db; 457 int hshift; 458 unsigned int max_ent; 459 unsigned int n_bits; 460 unsigned int bitno; 461 unsigned long accm; 462 int ent; 463 unsigned long fcode; 464 struct bsd_dict *dictp; 465 unsigned char c; 466 int hval,disp,ilen,mxcode; 467 unsigned char *rptr = skb_in->data; 468 int isize = skb_in->len; 469 470#define OUTPUT(ent) \ 471 { \ 472 bitno -= n_bits; \ 473 accm |= ((ent) << bitno); \ 474 do { \ 475 if(skb_out && skb_tailroom(skb_out) > 0) \ 476 *(skb_put(skb_out,1)) = (unsigned char) (accm>>24); \ 477 accm <<= 8; \ 478 bitno += 8; \ 479 } while (bitno <= 24); \ 480 } 481 482 /* 483 * If the protocol is not in the range we're interested in, 484 * just return without compressing the packet. If it is, 485 * the protocol becomes the first byte to compress. 486 */ 487 printk(KERN_DEBUG "bsd_compress called with %x\n",proto); 488 489 ent = proto; 490 if (proto < 0x21 || proto > 0xf9 || !(proto & 0x1) ) 491 return 0; 492 493 db = (struct bsd_db *) state; 494 hshift = db->hshift; 495 max_ent = db->max_ent; 496 n_bits = db->n_bits; 497 bitno = 32; 498 accm = 0; 499 mxcode = MAXCODE (n_bits); 500 501 /* This is the PPP header information */ 502 if(skb_out && skb_tailroom(skb_out) >= 2) { 503 char *v = skb_put(skb_out,2); 504 /* we only push our own data on the header, 505 AC,PC and protos is pushed by caller */ 506 v[0] = db->seqno >> 8; 507 v[1] = db->seqno; 508 } 509 510 ilen = ++isize; /* This is off by one, but that is what is in draft! */ 511 512 while (--ilen > 0) { 513 c = *rptr++; 514 fcode = BSD_KEY (ent, c); 515 hval = BSD_HASH (ent, c, hshift); 516 dictp = dict_ptr (db, hval); 517 518 /* Validate and then check the entry. */ 519 if (dictp->codem1 >= max_ent) 520 goto nomatch; 521 522 if (dictp->fcode == fcode) { 523 ent = dictp->codem1 + 1; 524 continue; /* found (prefix,suffix) */ 525 } 526 527 /* continue probing until a match or invalid entry */ 528 disp = (hval == 0) ? 1 : hval; 529 530 do { 531 hval += disp; 532 if (hval >= db->hsize) 533 hval -= db->hsize; 534 dictp = dict_ptr (db, hval); 535 if (dictp->codem1 >= max_ent) 536 goto nomatch; 537 } while (dictp->fcode != fcode); 538 539 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ 540 continue; 541 542nomatch: 543 OUTPUT(ent); /* output the prefix */ 544 545 /* code -> hashtable */ 546 if (max_ent < db->maxmaxcode) { 547 struct bsd_dict *dictp2; 548 struct bsd_dict *dictp3; 549 int indx; 550 551 /* expand code size if needed */ 552 if (max_ent >= mxcode) { 553 db->n_bits = ++n_bits; 554 mxcode = MAXCODE (n_bits); 555 } 556 557 /* 558 * Invalidate old hash table entry using 559 * this code, and then take it over. 560 */ 561 dictp2 = dict_ptr (db, max_ent + 1); 562 indx = dictp2->cptr; 563 dictp3 = dict_ptr (db, indx); 564 565 if (dictp3->codem1 == max_ent) 566 dictp3->codem1 = BADCODEM1; 567 568 dictp2->cptr = hval; 569 dictp->codem1 = max_ent; 570 dictp->fcode = fcode; 571 db->max_ent = ++max_ent; 572 573 if (db->lens) { 574 unsigned short *len1 = lens_ptr (db, max_ent); 575 unsigned short *len2 = lens_ptr (db, ent); 576 *len1 = *len2 + 1; 577 } 578 } 579 ent = c; 580 } 581 582 OUTPUT(ent); /* output the last code */ 583 584 if(skb_out) 585 db->bytes_out += skb_out->len; /* Do not count bytes from here */ 586 db->uncomp_bytes += isize; 587 db->in_count += isize; 588 ++db->uncomp_count; 589 ++db->seqno; 590 591 if (bitno < 32) 592 ++db->bytes_out; /* must be set before calling bsd_check */ 593 594 /* 595 * Generate the clear command if needed 596 */ 597 598 if (bsd_check(db)) 599 OUTPUT (CLEAR); 600 601 /* 602 * Pad dribble bits of last code with ones. 603 * Do not emit a completely useless byte of ones. 604 */ 605 if (bitno < 32 && skb_out && skb_tailroom(skb_out) > 0) 606 *(skb_put(skb_out,1)) = (unsigned char) ((accm | (0xff << (bitno-8))) >> 24); 607 608 /* 609 * Increase code size if we would have without the packet 610 * boundary because the decompressor will do so. 611 */ 612 if (max_ent >= mxcode && max_ent < db->maxmaxcode) 613 db->n_bits++; 614 615 /* If output length is too large then this is an incompressible frame. */ 616 if (!skb_out || (skb_out && skb_out->len >= skb_in->len) ) { 617 ++db->incomp_count; 618 db->incomp_bytes += isize; 619 return 0; 620 } 621 622 /* Count the number of compressed frames */ 623 ++db->comp_count; 624 db->comp_bytes += skb_out->len; 625 return skb_out->len; 626 627#undef OUTPUT 628} 629 630/* 631 * Update the "BSD Compress" dictionary on the receiver for 632 * incompressible data by pretending to compress the incoming data. 633 */ 634static void bsd_incomp (void *state, struct sk_buff *skb_in,int proto) 635{ 636 bsd_compress (state, skb_in, NULL, proto); 637} 638 639/* 640 * Decompress "BSD Compress". 641 */ 642static int bsd_decompress (void *state, struct sk_buff *skb_in, struct sk_buff *skb_out, 643 struct isdn_ppp_resetparams *rsparm) 644{ 645 struct bsd_db *db; 646 unsigned int max_ent; 647 unsigned long accm; 648 unsigned int bitno; /* 1st valid bit in accm */ 649 unsigned int n_bits; 650 unsigned int tgtbitno; /* bitno when we have a code */ 651 struct bsd_dict *dictp; 652 int seq; 653 unsigned int incode; 654 unsigned int oldcode; 655 unsigned int finchar; 656 unsigned char *p,*ibuf; 657 int ilen; 658 int codelen; 659 int extra; 660 661 db = (struct bsd_db *) state; 662 max_ent = db->max_ent; 663 accm = 0; 664 bitno = 32; /* 1st valid bit in accm */ 665 n_bits = db->n_bits; 666 tgtbitno = 32 - n_bits; /* bitno when we have a code */ 667 668 printk(KERN_DEBUG "bsd_decompress called\n"); 669 670 if(!skb_in || !skb_out) { 671 printk(KERN_ERR "bsd_decompress called with NULL parameter\n"); 672 return DECOMP_ERROR; 673 } 674 675 /* 676 * Get the sequence number. 677 */ 678 if( (p = skb_pull(skb_in,2)) == NULL) { 679 return DECOMP_ERROR; 680 } 681 p-=2; 682 seq = (p[0] << 8) + p[1]; 683 ilen = skb_in->len; 684 ibuf = skb_in->data; 685 686 /* 687 * Check the sequence number and give up if it differs from 688 * the value we're expecting. 689 */ 690 if (seq != db->seqno) { 691 if (db->debug) { 692 printk(KERN_DEBUG "bsd_decomp%d: bad sequence # %d, expected %d\n", 693 db->unit, seq, db->seqno - 1); 694 } 695 return DECOMP_ERROR; 696 } 697 698 ++db->seqno; 699 db->bytes_out += ilen; 700 701 if(skb_tailroom(skb_out) > 0) 702 *(skb_put(skb_out,1)) = 0; 703 else 704 return DECOMP_ERR_NOMEM; 705 706 oldcode = CLEAR; 707 708 /* 709 * Keep the checkpoint correctly so that incompressible packets 710 * clear the dictionary at the proper times. 711 */ 712 713 for (;;) { 714 if (ilen-- <= 0) { 715 db->in_count += (skb_out->len - 1); /* don't count the header */ 716 break; 717 } 718 719 /* 720 * Accumulate bytes until we have a complete code. 721 * Then get the next code, relying on the 32-bit, 722 * unsigned accm to mask the result. 723 */ 724 725 bitno -= 8; 726 accm |= *ibuf++ << bitno; 727 if (tgtbitno < bitno) 728 continue; 729 730 incode = accm >> tgtbitno; 731 accm <<= n_bits; 732 bitno += n_bits; 733 734 /* 735 * The dictionary must only be cleared at the end of a packet. 736 */ 737 738 if (incode == CLEAR) { 739 if (ilen > 0) { 740 if (db->debug) 741 printk(KERN_DEBUG "bsd_decomp%d: bad CLEAR\n", db->unit); 742 return DECOMP_FATALERROR; /* probably a bug */ 743 } 744 bsd_clear(db); 745 break; 746 } 747 748 if ((incode > max_ent + 2) || (incode > db->maxmaxcode) 749 || (incode > max_ent && oldcode == CLEAR)) { 750 if (db->debug) { 751 printk(KERN_DEBUG "bsd_decomp%d: bad code 0x%x oldcode=0x%x ", 752 db->unit, incode, oldcode); 753 printk(KERN_DEBUG "max_ent=0x%x skb->Len=%d seqno=%d\n", 754 max_ent, skb_out->len, db->seqno); 755 } 756 return DECOMP_FATALERROR; /* probably a bug */ 757 } 758 759 /* Special case for KwKwK string. */ 760 if (incode > max_ent) { 761 finchar = oldcode; 762 extra = 1; 763 } else { 764 finchar = incode; 765 extra = 0; 766 } 767 768 codelen = *(lens_ptr (db, finchar)); 769 if( skb_tailroom(skb_out) < codelen + extra) { 770 if (db->debug) { 771 printk(KERN_DEBUG "bsd_decomp%d: ran out of mru\n", db->unit); 772#ifdef DEBUG 773 printk(KERN_DEBUG " len=%d, finchar=0x%x, codelen=%d,skblen=%d\n", 774 ilen, finchar, codelen, skb_out->len); 775#endif 776 } 777 return DECOMP_FATALERROR; 778 } 779 780 /* 781 * Decode this code and install it in the decompressed buffer. 782 */ 783 784 p = skb_put(skb_out,codelen); 785 p += codelen; 786 while (finchar > LAST) { 787 struct bsd_dict *dictp2 = dict_ptr (db, finchar); 788 789 dictp = dict_ptr (db, dictp2->cptr); 790 791#ifdef DEBUG 792 if (--codelen <= 0 || dictp->codem1 != finchar-1) { 793 if (codelen <= 0) { 794 printk(KERN_ERR "bsd_decomp%d: fell off end of chain ", db->unit); 795 printk(KERN_ERR "0x%x at 0x%x by 0x%x, max_ent=0x%x\n", incode, finchar, dictp2->cptr, max_ent); 796 } else { 797 if (dictp->codem1 != finchar-1) { 798 printk(KERN_ERR "bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",db->unit, incode, finchar); 799 printk(KERN_ERR "oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, dictp2->cptr, dictp->codem1); 800 } 801 } 802 return DECOMP_FATALERROR; 803 } 804#endif 805 806 { 807 u32 fcode = dictp->fcode; 808 *--p = (fcode >> 16) & 0xff; 809 finchar = fcode & 0xffff; 810 } 811 } 812 *--p = finchar; 813 814#ifdef DEBUG 815 if (--codelen != 0) 816 printk(KERN_ERR "bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", db->unit, codelen, incode, max_ent); 817#endif 818 819 if (extra) /* the KwKwK case again */ 820 *(skb_put(skb_out,1)) = finchar; 821 822 /* 823 * If not first code in a packet, and 824 * if not out of code space, then allocate a new code. 825 * 826 * Keep the hash table correct so it can be used 827 * with uncompressed packets. 828 */ 829 if (oldcode != CLEAR && max_ent < db->maxmaxcode) { 830 struct bsd_dict *dictp2, *dictp3; 831 u16 *lens1, *lens2; 832 unsigned long fcode; 833 int hval, disp, indx; 834 835 fcode = BSD_KEY(oldcode,finchar); 836 hval = BSD_HASH(oldcode,finchar,db->hshift); 837 dictp = dict_ptr (db, hval); 838 839 /* look for a free hash table entry */ 840 if (dictp->codem1 < max_ent) { 841 disp = (hval == 0) ? 1 : hval; 842 do { 843 hval += disp; 844 if (hval >= db->hsize) 845 hval -= db->hsize; 846 dictp = dict_ptr (db, hval); 847 } while (dictp->codem1 < max_ent); 848 } 849 850 /* 851 * Invalidate previous hash table entry 852 * assigned this code, and then take it over 853 */ 854 855 dictp2 = dict_ptr (db, max_ent + 1); 856 indx = dictp2->cptr; 857 dictp3 = dict_ptr (db, indx); 858 859 if (dictp3->codem1 == max_ent) 860 dictp3->codem1 = BADCODEM1; 861 862 dictp2->cptr = hval; 863 dictp->codem1 = max_ent; 864 dictp->fcode = fcode; 865 db->max_ent = ++max_ent; 866 867 /* Update the length of this string. */ 868 lens1 = lens_ptr (db, max_ent); 869 lens2 = lens_ptr (db, oldcode); 870 *lens1 = *lens2 + 1; 871 872 /* Expand code size if needed. */ 873 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { 874 db->n_bits = ++n_bits; 875 tgtbitno = 32-n_bits; 876 } 877 } 878 oldcode = incode; 879 } 880 881 ++db->comp_count; 882 ++db->uncomp_count; 883 db->comp_bytes += skb_in->len - BSD_OVHD; 884 db->uncomp_bytes += skb_out->len; 885 886 if (bsd_check(db)) { 887 if (db->debug) 888 printk(KERN_DEBUG "bsd_decomp%d: peer should have cleared dictionary on %d\n", 889 db->unit, db->seqno - 1); 890 } 891 return skb_out->len; 892} 893 894/************************************************************* 895 * Table of addresses for the BSD compression module 896 *************************************************************/ 897 898static struct isdn_ppp_compressor ippp_bsd_compress = { 899 .owner = THIS_MODULE, 900 .num = CI_BSD_COMPRESS, 901 .alloc = bsd_alloc, 902 .free = bsd_free, 903 .init = bsd_init, 904 .reset = bsd_reset, 905 .compress = bsd_compress, 906 .decompress = bsd_decompress, 907 .incomp = bsd_incomp, 908 .stat = bsd_stats, 909}; 910 911/************************************************************* 912 * Module support routines 913 *************************************************************/ 914 915static int __init isdn_bsdcomp_init(void) 916{ 917 int answer = isdn_ppp_register_compressor (&ippp_bsd_compress); 918 if (answer == 0) 919 printk (KERN_INFO "PPP BSD Compression module registered\n"); 920 return answer; 921} 922 923static void __exit isdn_bsdcomp_exit(void) 924{ 925 isdn_ppp_unregister_compressor (&ippp_bsd_compress); 926} 927 928module_init(isdn_bsdcomp_init); 929module_exit(isdn_bsdcomp_exit); 930