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