1/* Because this code is derived from the 4.3BSD compress source: 2 * 3 * 4 * Copyright (c) 1985, 1986 The Regents of the University of California. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * James A. Woods, derived from original work by Spencer Thomas 9 * and Joseph Orost. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40/* 41 * This version is for use with STREAMS under SunOS 4.x, 42 * Digital UNIX, AIX 4.x, and SVR4 systems including Solaris 2. 43 * 44 * $Id: bsd-comp.c,v 1.1.1.1 2008/10/15 03:30:51 james26_jang Exp $ 45 */ 46 47#ifdef AIX4 48#include <net/net_globals.h> 49#endif 50#include <sys/param.h> 51#include <sys/types.h> 52#include <sys/stream.h> 53#include <net/ppp_defs.h> 54#include "ppp_mod.h" 55 56#ifdef SVR4 57#include <sys/byteorder.h> 58#ifndef _BIG_ENDIAN 59#define BSD_LITTLE_ENDIAN 60#endif 61#endif 62 63#ifdef __osf__ 64#undef FIRST 65#undef LAST 66#define BSD_LITTLE_ENDIAN 67#endif 68 69#define PACKETPTR mblk_t * 70#include <net/ppp-comp.h> 71 72#if DO_BSD_COMPRESS 73 74/* 75 * PPP "BSD compress" compression 76 * The differences between this compression and the classic BSD LZW 77 * source are obvious from the requirement that the classic code worked 78 * with files while this handles arbitrarily long streams that 79 * are broken into packets. They are: 80 * 81 * When the code size expands, a block of junk is not emitted by 82 * the compressor and not expected by the decompressor. 83 * 84 * New codes are not necessarily assigned every time an old 85 * code is output by the compressor. This is because a packet 86 * end forces a code to be emitted, but does not imply that a 87 * new sequence has been seen. 88 * 89 * The compression ratio is checked at the first end of a packet 90 * after the appropriate gap. Besides simplifying and speeding 91 * things up, this makes it more likely that the transmitter 92 * and receiver will agree when the dictionary is cleared when 93 * compression is not going well. 94 */ 95 96/* 97 * A dictionary for doing BSD compress. 98 */ 99struct bsd_db { 100 int totlen; /* length of this structure */ 101 u_int hsize; /* size of the hash table */ 102 u_char hshift; /* used in hash function */ 103 u_char n_bits; /* current bits/code */ 104 u_char maxbits; 105 u_char debug; 106 u_char unit; 107 u_short seqno; /* sequence number of next packet */ 108 u_int hdrlen; /* header length to preallocate */ 109 u_int mru; 110 u_int maxmaxcode; /* largest valid code */ 111 u_int max_ent; /* largest code in use */ 112 u_int in_count; /* uncompressed bytes, aged */ 113 u_int bytes_out; /* compressed bytes, aged */ 114 u_int ratio; /* recent compression ratio */ 115 u_int checkpoint; /* when to next check the ratio */ 116 u_int clear_count; /* times dictionary cleared */ 117 u_int incomp_count; /* incompressible packets */ 118 u_int incomp_bytes; /* incompressible bytes */ 119 u_int uncomp_count; /* uncompressed packets */ 120 u_int uncomp_bytes; /* uncompressed bytes */ 121 u_int comp_count; /* compressed packets */ 122 u_int comp_bytes; /* compressed bytes */ 123 u_short *lens; /* array of lengths of codes */ 124 struct bsd_dict { 125 union { /* hash value */ 126 u_int32_t fcode; 127 struct { 128#ifdef BSD_LITTLE_ENDIAN 129 u_short prefix; /* preceding code */ 130 u_char suffix; /* last character of new code */ 131 u_char pad; 132#else 133 u_char pad; 134 u_char suffix; /* last character of new code */ 135 u_short prefix; /* preceding code */ 136#endif 137 } hs; 138 } f; 139 u_short codem1; /* output of hash table -1 */ 140 u_short cptr; /* map code to hash table entry */ 141 } dict[1]; 142}; 143 144#define BSD_OVHD 2 /* BSD compress overhead/packet */ 145#define BSD_INIT_BITS BSD_MIN_BITS 146 147static void *bsd_comp_alloc __P((u_char *options, int opt_len)); 148static void *bsd_decomp_alloc __P((u_char *options, int opt_len)); 149static void bsd_free __P((void *state)); 150static int bsd_comp_init __P((void *state, u_char *options, int opt_len, 151 int unit, int hdrlen, int debug)); 152static int bsd_decomp_init __P((void *state, u_char *options, int opt_len, 153 int unit, int hdrlen, int mru, int debug)); 154static int bsd_compress __P((void *state, mblk_t **mret, 155 mblk_t *mp, int slen, int maxolen)); 156static void bsd_incomp __P((void *state, mblk_t *dmsg)); 157static int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp)); 158static void bsd_reset __P((void *state)); 159static void bsd_comp_stats __P((void *state, struct compstat *stats)); 160 161/* 162 * Procedures exported to ppp_comp.c. 163 */ 164struct compressor ppp_bsd_compress = { 165 CI_BSD_COMPRESS, /* compress_proto */ 166 bsd_comp_alloc, /* comp_alloc */ 167 bsd_free, /* comp_free */ 168 bsd_comp_init, /* comp_init */ 169 bsd_reset, /* comp_reset */ 170 bsd_compress, /* compress */ 171 bsd_comp_stats, /* comp_stat */ 172 bsd_decomp_alloc, /* decomp_alloc */ 173 bsd_free, /* decomp_free */ 174 bsd_decomp_init, /* decomp_init */ 175 bsd_reset, /* decomp_reset */ 176 bsd_decompress, /* decompress */ 177 bsd_incomp, /* incomp */ 178 bsd_comp_stats, /* decomp_stat */ 179}; 180 181/* 182 * the next two codes should not be changed lightly, as they must not 183 * lie within the contiguous general code space. 184 */ 185#define CLEAR 256 /* table clear output code */ 186#define FIRST 257 /* first free entry */ 187#define LAST 255 188 189#define MAXCODE(b) ((1 << (b)) - 1) 190#define BADCODEM1 MAXCODE(BSD_MAX_BITS) 191 192#define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \ 193 ^ (u_int32_t)(prefix)) 194#define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \ 195 + (u_int32_t)(prefix)) 196 197#define CHECK_GAP 10000 /* Ratio check interval */ 198 199#define RATIO_SCALE_LOG 8 200#define RATIO_SCALE (1<<RATIO_SCALE_LOG) 201#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) 202 203#define DECOMP_CHUNK 256 204 205/* 206 * clear the dictionary 207 */ 208static void 209bsd_clear(db) 210 struct bsd_db *db; 211{ 212 db->clear_count++; 213 db->max_ent = FIRST-1; 214 db->n_bits = BSD_INIT_BITS; 215 db->ratio = 0; 216 db->bytes_out = 0; 217 db->in_count = 0; 218 db->checkpoint = CHECK_GAP; 219} 220 221/* 222 * If the dictionary is full, then see if it is time to reset it. 223 * 224 * Compute the compression ratio using fixed-point arithmetic 225 * with 8 fractional bits. 226 * 227 * Since we have an infinite stream instead of a single file, 228 * watch only the local compression ratio. 229 * 230 * Since both peers must reset the dictionary at the same time even in 231 * the absence of CLEAR codes (while packets are incompressible), they 232 * must compute the same ratio. 233 */ 234static int /* 1=output CLEAR */ 235bsd_check(db) 236 struct bsd_db *db; 237{ 238 u_int new_ratio; 239 240 if (db->in_count >= db->checkpoint) { 241 /* age the ratio by limiting the size of the counts */ 242 if (db->in_count >= RATIO_MAX 243 || db->bytes_out >= RATIO_MAX) { 244 db->in_count -= db->in_count/4; 245 db->bytes_out -= db->bytes_out/4; 246 } 247 248 db->checkpoint = db->in_count + CHECK_GAP; 249 250 if (db->max_ent >= db->maxmaxcode) { 251 /* Reset the dictionary only if the ratio is worse, 252 * or if it looks as if it has been poisoned 253 * by incompressible data. 254 * 255 * This does not overflow, because 256 * db->in_count <= RATIO_MAX. 257 */ 258 new_ratio = db->in_count << RATIO_SCALE_LOG; 259 if (db->bytes_out != 0) 260 new_ratio /= db->bytes_out; 261 262 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) { 263 bsd_clear(db); 264 return 1; 265 } 266 db->ratio = new_ratio; 267 } 268 } 269 return 0; 270} 271 272/* 273 * Return statistics. 274 */ 275static void 276bsd_comp_stats(state, stats) 277 void *state; 278 struct compstat *stats; 279{ 280 struct bsd_db *db = (struct bsd_db *) state; 281 u_int out; 282 283 stats->unc_bytes = db->uncomp_bytes; 284 stats->unc_packets = db->uncomp_count; 285 stats->comp_bytes = db->comp_bytes; 286 stats->comp_packets = db->comp_count; 287 stats->inc_bytes = db->incomp_bytes; 288 stats->inc_packets = db->incomp_count; 289 stats->ratio = db->in_count; 290 out = db->bytes_out; 291 if (stats->ratio <= 0x7fffff) 292 stats->ratio <<= 8; 293 else 294 out >>= 8; 295 if (out != 0) 296 stats->ratio /= out; 297} 298 299/* 300 * Reset state, as on a CCP ResetReq. 301 */ 302static void 303bsd_reset(state) 304 void *state; 305{ 306 struct bsd_db *db = (struct bsd_db *) state; 307 308 db->seqno = 0; 309 bsd_clear(db); 310 db->clear_count = 0; 311} 312 313/* 314 * Allocate space for a (de) compressor. 315 */ 316static void * 317bsd_alloc(options, opt_len, decomp) 318 u_char *options; 319 int opt_len, decomp; 320{ 321 int bits; 322 u_int newlen, hsize, hshift, maxmaxcode; 323 struct bsd_db *db; 324 325 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3 326 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) 327 return NULL; 328 329 bits = BSD_NBITS(options[2]); 330 switch (bits) { 331 case 9: /* needs 82152 for both directions */ 332 case 10: /* needs 84144 */ 333 case 11: /* needs 88240 */ 334 case 12: /* needs 96432 */ 335 hsize = 5003; 336 hshift = 4; 337 break; 338 case 13: /* needs 176784 */ 339 hsize = 9001; 340 hshift = 5; 341 break; 342 case 14: /* needs 353744 */ 343 hsize = 18013; 344 hshift = 6; 345 break; 346 case 15: /* needs 691440 */ 347 hsize = 35023; 348 hshift = 7; 349 break; 350 case 16: /* needs 1366160--far too much, */ 351 /* hsize = 69001; */ /* and 69001 is too big for cptr */ 352 /* hshift = 8; */ /* in struct bsd_db */ 353 /* break; */ 354 default: 355 return NULL; 356 } 357 358 maxmaxcode = MAXCODE(bits); 359 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0])); 360#ifdef __osf__ 361 db = (struct bsd_db *) ALLOC_SLEEP(newlen); 362#else 363 db = (struct bsd_db *) ALLOC_NOSLEEP(newlen); 364#endif 365 if (!db) 366 return NULL; 367 bzero(db, sizeof(*db) - sizeof(db->dict)); 368 369 if (!decomp) { 370 db->lens = NULL; 371 } else { 372#ifdef __osf__ 373 db->lens = (u_short *) ALLOC_SLEEP((maxmaxcode+1) * sizeof(db->lens[0])); 374#else 375 db->lens = (u_short *) ALLOC_NOSLEEP((maxmaxcode+1) * sizeof(db->lens[0])); 376#endif 377 if (!db->lens) { 378 FREE(db, newlen); 379 return NULL; 380 } 381 } 382 383 db->totlen = newlen; 384 db->hsize = hsize; 385 db->hshift = hshift; 386 db->maxmaxcode = maxmaxcode; 387 db->maxbits = bits; 388 389 return (void *) db; 390} 391 392static void 393bsd_free(state) 394 void *state; 395{ 396 struct bsd_db *db = (struct bsd_db *) state; 397 398 if (db->lens) 399 FREE(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0])); 400 FREE(db, db->totlen); 401} 402 403static void * 404bsd_comp_alloc(options, opt_len) 405 u_char *options; 406 int opt_len; 407{ 408 return bsd_alloc(options, opt_len, 0); 409} 410 411static void * 412bsd_decomp_alloc(options, opt_len) 413 u_char *options; 414 int opt_len; 415{ 416 return bsd_alloc(options, opt_len, 1); 417} 418 419/* 420 * Initialize the database. 421 */ 422static int 423bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp) 424 struct bsd_db *db; 425 u_char *options; 426 int opt_len, unit, hdrlen, mru, debug, decomp; 427{ 428 int i; 429 430 if (opt_len < CILEN_BSD_COMPRESS 431 || options[0] != CI_BSD_COMPRESS || options[1] != CILEN_BSD_COMPRESS 432 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION 433 || BSD_NBITS(options[2]) != db->maxbits 434 || decomp && db->lens == NULL) 435 return 0; 436 437 if (decomp) { 438 i = LAST+1; 439 while (i != 0) 440 db->lens[--i] = 1; 441 } 442 i = db->hsize; 443 while (i != 0) { 444 db->dict[--i].codem1 = BADCODEM1; 445 db->dict[i].cptr = 0; 446 } 447 448 db->unit = unit; 449 db->hdrlen = hdrlen; 450 db->mru = mru; 451 if (debug) 452 db->debug = 1; 453 454 bsd_reset(db); 455 456 return 1; 457} 458 459static int 460bsd_comp_init(state, options, opt_len, unit, hdrlen, debug) 461 void *state; 462 u_char *options; 463 int opt_len, unit, hdrlen, debug; 464{ 465 return bsd_init((struct bsd_db *) state, options, opt_len, 466 unit, hdrlen, 0, debug, 0); 467} 468 469static int 470bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug) 471 void *state; 472 u_char *options; 473 int opt_len, unit, hdrlen, mru, debug; 474{ 475 return bsd_init((struct bsd_db *) state, options, opt_len, 476 unit, hdrlen, mru, debug, 1); 477} 478 479 480/* 481 * compress a packet 482 * One change from the BSD compress command is that when the 483 * code size expands, we do not output a bunch of padding. 484 * 485 * N.B. at present, we ignore the hdrlen specified in the comp_init call. 486 */ 487static int /* new slen */ 488bsd_compress(state, mretp, mp, slen, maxolen) 489 void *state; 490 mblk_t **mretp; /* return compressed mbuf chain here */ 491 mblk_t *mp; /* from here */ 492 int slen; /* uncompressed length */ 493 int maxolen; /* max compressed length */ 494{ 495 struct bsd_db *db = (struct bsd_db *) state; 496 int hshift = db->hshift; 497 u_int max_ent = db->max_ent; 498 u_int n_bits = db->n_bits; 499 u_int bitno = 32; 500 u_int32_t accm = 0, fcode; 501 struct bsd_dict *dictp; 502 u_char c; 503 int hval, disp, ent, ilen; 504 mblk_t *np, *mret; 505 u_char *rptr, *wptr; 506 u_char *cp_end; 507 int olen; 508 mblk_t *m, **mnp; 509 510#define PUTBYTE(v) { \ 511 if (wptr) { \ 512 *wptr++ = (v); \ 513 if (wptr >= cp_end) { \ 514 m->b_wptr = wptr; \ 515 m = m->b_cont; \ 516 if (m) { \ 517 wptr = m->b_wptr; \ 518 cp_end = m->b_datap->db_lim; \ 519 } else \ 520 wptr = NULL; \ 521 } \ 522 } \ 523 ++olen; \ 524} 525 526#define OUTPUT(ent) { \ 527 bitno -= n_bits; \ 528 accm |= ((ent) << bitno); \ 529 do { \ 530 PUTBYTE(accm >> 24); \ 531 accm <<= 8; \ 532 bitno += 8; \ 533 } while (bitno <= 24); \ 534} 535 536 /* 537 * First get the protocol and check that we're 538 * interested in this packet. 539 */ 540 *mretp = NULL; 541 rptr = mp->b_rptr; 542 if (rptr + PPP_HDRLEN > mp->b_wptr) { 543 if (!pullupmsg(mp, PPP_HDRLEN)) 544 return 0; 545 rptr = mp->b_rptr; 546 } 547 ent = PPP_PROTOCOL(rptr); /* get the protocol */ 548 if (ent < 0x21 || ent > 0xf9) 549 return 0; 550 551 /* Don't generate compressed packets which are larger than 552 the uncompressed packet. */ 553 if (maxolen > slen) 554 maxolen = slen; 555 556 /* Allocate enough message blocks to give maxolen total space. */ 557 mnp = &mret; 558 for (olen = maxolen; olen > 0; ) { 559 m = allocb((olen < 4096? olen: 4096), BPRI_MED); 560 *mnp = m; 561 if (m == NULL) { 562 if (mret != NULL) { 563 freemsg(mret); 564 mnp = &mret; 565 } 566 break; 567 } 568 mnp = &m->b_cont; 569 olen -= m->b_datap->db_lim - m->b_wptr; 570 } 571 *mnp = NULL; 572 573 if ((m = mret) != NULL) { 574 wptr = m->b_wptr; 575 cp_end = m->b_datap->db_lim; 576 } else 577 wptr = cp_end = NULL; 578 olen = 0; 579 580 /* 581 * Copy the PPP header over, changing the protocol, 582 * and install the 2-byte sequence number. 583 */ 584 if (wptr) { 585 wptr[0] = PPP_ADDRESS(rptr); 586 wptr[1] = PPP_CONTROL(rptr); 587 wptr[2] = 0; /* change the protocol */ 588 wptr[3] = PPP_COMP; 589 wptr[4] = db->seqno >> 8; 590 wptr[5] = db->seqno; 591 wptr += PPP_HDRLEN + BSD_OVHD; 592 } 593 ++db->seqno; 594 rptr += PPP_HDRLEN; 595 596 slen = mp->b_wptr - rptr; 597 ilen = slen + 1; 598 np = mp->b_cont; 599 for (;;) { 600 if (slen <= 0) { 601 if (!np) 602 break; 603 rptr = np->b_rptr; 604 slen = np->b_wptr - rptr; 605 np = np->b_cont; 606 if (!slen) 607 continue; /* handle 0-length buffers */ 608 ilen += slen; 609 } 610 611 slen--; 612 c = *rptr++; 613 fcode = BSD_KEY(ent, c); 614 hval = BSD_HASH(ent, c, hshift); 615 dictp = &db->dict[hval]; 616 617 /* Validate and then check the entry. */ 618 if (dictp->codem1 >= max_ent) 619 goto nomatch; 620 if (dictp->f.fcode == fcode) { 621 ent = dictp->codem1+1; 622 continue; /* found (prefix,suffix) */ 623 } 624 625 /* continue probing until a match or invalid entry */ 626 disp = (hval == 0) ? 1 : hval; 627 do { 628 hval += disp; 629 if (hval >= db->hsize) 630 hval -= db->hsize; 631 dictp = &db->dict[hval]; 632 if (dictp->codem1 >= max_ent) 633 goto nomatch; 634 } while (dictp->f.fcode != fcode); 635 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ 636 continue; 637 638 nomatch: 639 OUTPUT(ent); /* output the prefix */ 640 641 /* code -> hashtable */ 642 if (max_ent < db->maxmaxcode) { 643 struct bsd_dict *dictp2; 644 /* expand code size if needed */ 645 if (max_ent >= MAXCODE(n_bits)) 646 db->n_bits = ++n_bits; 647 648 /* Invalidate old hash table entry using 649 * this code, and then take it over. 650 */ 651 dictp2 = &db->dict[max_ent+1]; 652 if (db->dict[dictp2->cptr].codem1 == max_ent) 653 db->dict[dictp2->cptr].codem1 = BADCODEM1; 654 dictp2->cptr = hval; 655 dictp->codem1 = max_ent; 656 dictp->f.fcode = fcode; 657 658 db->max_ent = ++max_ent; 659 } 660 ent = c; 661 } 662 663 OUTPUT(ent); /* output the last code */ 664 db->bytes_out += olen; 665 db->in_count += ilen; 666 if (bitno < 32) 667 ++db->bytes_out; /* count complete bytes */ 668 669 if (bsd_check(db)) 670 OUTPUT(CLEAR); /* do not count the CLEAR */ 671 672 /* 673 * Pad dribble bits of last code with ones. 674 * Do not emit a completely useless byte of ones. 675 */ 676 if (bitno != 32) 677 PUTBYTE((accm | (0xff << (bitno-8))) >> 24); 678 679 /* 680 * Increase code size if we would have without the packet 681 * boundary and as the decompressor will. 682 */ 683 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) 684 db->n_bits++; 685 686 db->uncomp_bytes += ilen; 687 ++db->uncomp_count; 688 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) { 689 /* throw away the compressed stuff if it is longer than uncompressed */ 690 freemsg(mret); 691 mret = NULL; 692 ++db->incomp_count; 693 db->incomp_bytes += ilen; 694 } else if (wptr != NULL) { 695 m->b_wptr = wptr; 696 if (m->b_cont) { 697 freemsg(m->b_cont); 698 m->b_cont = NULL; 699 } 700 ++db->comp_count; 701 db->comp_bytes += olen + BSD_OVHD; 702 } 703 704 *mretp = mret; 705 return olen + PPP_HDRLEN + BSD_OVHD; 706#undef OUTPUT 707#undef PUTBYTE 708} 709 710 711/* 712 * Update the "BSD Compress" dictionary on the receiver for 713 * incompressible data by pretending to compress the incoming data. 714 */ 715static void 716bsd_incomp(state, dmsg) 717 void *state; 718 mblk_t *dmsg; 719{ 720 struct bsd_db *db = (struct bsd_db *) state; 721 u_int hshift = db->hshift; 722 u_int max_ent = db->max_ent; 723 u_int n_bits = db->n_bits; 724 struct bsd_dict *dictp; 725 u_int32_t fcode; 726 u_char c; 727 long hval, disp; 728 int slen, ilen; 729 u_int bitno = 7; 730 u_char *rptr; 731 u_int ent; 732 733 rptr = dmsg->b_rptr; 734 if (rptr + PPP_HDRLEN > dmsg->b_wptr) { 735 if (!pullupmsg(dmsg, PPP_HDRLEN)) 736 return; 737 rptr = dmsg->b_rptr; 738 } 739 ent = PPP_PROTOCOL(rptr); /* get the protocol */ 740 if (ent < 0x21 || ent > 0xf9) 741 return; 742 743 db->seqno++; 744 ilen = 1; /* count the protocol as 1 byte */ 745 rptr += PPP_HDRLEN; 746 for (;;) { 747 slen = dmsg->b_wptr - rptr; 748 if (slen <= 0) { 749 dmsg = dmsg->b_cont; 750 if (!dmsg) 751 break; 752 rptr = dmsg->b_rptr; 753 continue; /* skip zero-length buffers */ 754 } 755 ilen += slen; 756 757 do { 758 c = *rptr++; 759 fcode = BSD_KEY(ent, c); 760 hval = BSD_HASH(ent, c, hshift); 761 dictp = &db->dict[hval]; 762 763 /* validate and then check the entry */ 764 if (dictp->codem1 >= max_ent) 765 goto nomatch; 766 if (dictp->f.fcode == fcode) { 767 ent = dictp->codem1+1; 768 continue; /* found (prefix,suffix) */ 769 } 770 771 /* continue probing until a match or invalid entry */ 772 disp = (hval == 0) ? 1 : hval; 773 do { 774 hval += disp; 775 if (hval >= db->hsize) 776 hval -= db->hsize; 777 dictp = &db->dict[hval]; 778 if (dictp->codem1 >= max_ent) 779 goto nomatch; 780 } while (dictp->f.fcode != fcode); 781 ent = dictp->codem1+1; 782 continue; /* finally found (prefix,suffix) */ 783 784 nomatch: /* output (count) the prefix */ 785 bitno += n_bits; 786 787 /* code -> hashtable */ 788 if (max_ent < db->maxmaxcode) { 789 struct bsd_dict *dictp2; 790 /* expand code size if needed */ 791 if (max_ent >= MAXCODE(n_bits)) 792 db->n_bits = ++n_bits; 793 794 /* Invalidate previous hash table entry 795 * assigned this code, and then take it over. 796 */ 797 dictp2 = &db->dict[max_ent+1]; 798 if (db->dict[dictp2->cptr].codem1 == max_ent) 799 db->dict[dictp2->cptr].codem1 = BADCODEM1; 800 dictp2->cptr = hval; 801 dictp->codem1 = max_ent; 802 dictp->f.fcode = fcode; 803 804 db->max_ent = ++max_ent; 805 db->lens[max_ent] = db->lens[ent]+1; 806 } 807 ent = c; 808 } while (--slen != 0); 809 } 810 bitno += n_bits; /* output (count) the last code */ 811 db->bytes_out += bitno/8; 812 db->in_count += ilen; 813 (void)bsd_check(db); 814 815 ++db->incomp_count; 816 db->incomp_bytes += ilen; 817 ++db->uncomp_count; 818 db->uncomp_bytes += ilen; 819 820 /* Increase code size if we would have without the packet 821 * boundary and as the decompressor will. 822 */ 823 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) 824 db->n_bits++; 825} 826 827 828/* 829 * Decompress "BSD Compress" 830 * 831 * Because of patent problems, we return DECOMP_ERROR for errors 832 * found by inspecting the input data and for system problems, but 833 * DECOMP_FATALERROR for any errors which could possibly be said to 834 * be being detected "after" decompression. For DECOMP_ERROR, 835 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be 836 * infringing a patent of Motorola's if we do, so we take CCP down 837 * instead. 838 * 839 * Given that the frame has the correct sequence number and a good FCS, 840 * errors such as invalid codes in the input most likely indicate a 841 * bug, so we return DECOMP_FATALERROR for them in order to turn off 842 * compression, even though they are detected by inspecting the input. 843 */ 844static int 845bsd_decompress(state, cmsg, dmpp) 846 void *state; 847 mblk_t *cmsg, **dmpp; 848{ 849 struct bsd_db *db = (struct bsd_db *) state; 850 u_int max_ent = db->max_ent; 851 u_int32_t accm = 0; 852 u_int bitno = 32; /* 1st valid bit in accm */ 853 u_int n_bits = db->n_bits; 854 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */ 855 struct bsd_dict *dictp; 856 int explen, i, seq, len; 857 u_int incode, oldcode, finchar; 858 u_char *p, *rptr, *wptr; 859 mblk_t *dmsg, *mret; 860 int adrs, ctrl, ilen; 861 int dlen, space, codelen, extra; 862 863 /* 864 * Get at least the BSD Compress header in the first buffer 865 */ 866 rptr = cmsg->b_rptr; 867 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) { 868 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) { 869 if (db->debug) 870 printf("bsd_decomp%d: failed to pullup\n", db->unit); 871 return DECOMP_ERROR; 872 } 873 rptr = cmsg->b_rptr; 874 } 875 876 /* 877 * Save the address/control from the PPP header 878 * and then get the sequence number. 879 */ 880 adrs = PPP_ADDRESS(rptr); 881 ctrl = PPP_CONTROL(rptr); 882 rptr += PPP_HDRLEN; 883 seq = (rptr[0] << 8) + rptr[1]; 884 rptr += BSD_OVHD; 885 ilen = len = cmsg->b_wptr - rptr; 886 887 /* 888 * Check the sequence number and give up if it is not what we expect. 889 */ 890 if (seq != db->seqno++) { 891 if (db->debug) 892 printf("bsd_decomp%d: bad sequence # %d, expected %d\n", 893 db->unit, seq, db->seqno - 1); 894 return DECOMP_ERROR; 895 } 896 897 /* 898 * Allocate one message block to start with. 899 */ 900 if ((dmsg = allocb(DECOMP_CHUNK + db->hdrlen, BPRI_MED)) == NULL) 901 return DECOMP_ERROR; 902 mret = dmsg; 903 dmsg->b_wptr += db->hdrlen; 904 dmsg->b_rptr = wptr = dmsg->b_wptr; 905 906 /* Fill in the ppp header, but not the last byte of the protocol 907 (that comes from the decompressed data). */ 908 wptr[0] = adrs; 909 wptr[1] = ctrl; 910 wptr[2] = 0; 911 wptr += PPP_HDRLEN - 1; 912 space = dmsg->b_datap->db_lim - wptr; 913 914 oldcode = CLEAR; 915 explen = 0; 916 for (;;) { 917 if (len == 0) { 918 cmsg = cmsg->b_cont; 919 if (!cmsg) /* quit at end of message */ 920 break; 921 rptr = cmsg->b_rptr; 922 len = cmsg->b_wptr - rptr; 923 ilen += len; 924 continue; /* handle 0-length buffers */ 925 } 926 927 /* 928 * Accumulate bytes until we have a complete code. 929 * Then get the next code, relying on the 32-bit, 930 * unsigned accm to mask the result. 931 */ 932 bitno -= 8; 933 accm |= *rptr++ << bitno; 934 --len; 935 if (tgtbitno < bitno) 936 continue; 937 incode = accm >> tgtbitno; 938 accm <<= n_bits; 939 bitno += n_bits; 940 941 if (incode == CLEAR) { 942 /* 943 * The dictionary must only be cleared at 944 * the end of a packet. But there could be an 945 * empty message block at the end. 946 */ 947 if (len > 0 || cmsg->b_cont != 0) { 948 if (cmsg->b_cont) 949 len += msgdsize(cmsg->b_cont); 950 if (len > 0) { 951 freemsg(dmsg); 952 if (db->debug) 953 printf("bsd_decomp%d: bad CLEAR\n", db->unit); 954 return DECOMP_FATALERROR; 955 } 956 } 957 bsd_clear(db); 958 explen = ilen = 0; 959 break; 960 } 961 962 if (incode > max_ent + 2 || incode > db->maxmaxcode 963 || incode > max_ent && oldcode == CLEAR) { 964 freemsg(dmsg); 965 if (db->debug) { 966 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", 967 db->unit, incode, oldcode); 968 printf("max_ent=0x%x dlen=%d seqno=%d\n", 969 max_ent, dlen, db->seqno); 970 } 971 return DECOMP_FATALERROR; /* probably a bug */ 972 } 973 974 /* Special case for KwKwK string. */ 975 if (incode > max_ent) { 976 finchar = oldcode; 977 extra = 1; 978 } else { 979 finchar = incode; 980 extra = 0; 981 } 982 983 codelen = db->lens[finchar]; 984 explen += codelen + extra; 985 if (explen > db->mru + 1) { 986 freemsg(dmsg); 987 if (db->debug) 988 printf("bsd_decomp%d: ran out of mru\n", db->unit); 989 return DECOMP_FATALERROR; 990 } 991 992 /* 993 * Decode this code and install it in the decompressed buffer. 994 */ 995 space -= codelen + extra; 996 if (space < 0) { 997 /* Allocate another message block. */ 998 dmsg->b_wptr = wptr; 999 dlen = codelen + extra; 1000 if (dlen < DECOMP_CHUNK) 1001 dlen = DECOMP_CHUNK; 1002 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) { 1003 freemsg(dmsg); 1004 return DECOMP_ERROR; 1005 } 1006 dmsg = dmsg->b_cont; 1007 wptr = dmsg->b_wptr; 1008 space = dmsg->b_datap->db_lim - wptr - codelen - extra; 1009 } 1010 p = (wptr += codelen); 1011 while (finchar > LAST) { 1012 dictp = &db->dict[db->dict[finchar].cptr]; 1013#ifdef DEBUG 1014 --codelen; 1015 if (codelen <= 0) { 1016 freemsg(dmsg); 1017 printf("bsd_decomp%d: fell off end of chain ", db->unit); 1018 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", 1019 incode, finchar, db->dict[finchar].cptr, max_ent); 1020 return DECOMP_FATALERROR; 1021 } 1022 if (dictp->codem1 != finchar-1) { 1023 freemsg(dmsg); 1024 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", 1025 db->unit, incode, finchar); 1026 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, 1027 db->dict[finchar].cptr, dictp->codem1); 1028 return DECOMP_FATALERROR; 1029 } 1030#endif 1031 *--p = dictp->f.hs.suffix; 1032 finchar = dictp->f.hs.prefix; 1033 } 1034 *--p = finchar; 1035 1036#ifdef DEBUG 1037 if (--codelen != 0) 1038 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", 1039 db->unit, codelen, incode, max_ent); 1040#endif 1041 1042 if (extra) /* the KwKwK case again */ 1043 *wptr++ = finchar; 1044 1045 /* 1046 * If not first code in a packet, and 1047 * if not out of code space, then allocate a new code. 1048 * 1049 * Keep the hash table correct so it can be used 1050 * with uncompressed packets. 1051 */ 1052 if (oldcode != CLEAR && max_ent < db->maxmaxcode) { 1053 struct bsd_dict *dictp2; 1054 u_int32_t fcode; 1055 int hval, disp; 1056 1057 fcode = BSD_KEY(oldcode,finchar); 1058 hval = BSD_HASH(oldcode,finchar,db->hshift); 1059 dictp = &db->dict[hval]; 1060 1061 /* look for a free hash table entry */ 1062 if (dictp->codem1 < max_ent) { 1063 disp = (hval == 0) ? 1 : hval; 1064 do { 1065 hval += disp; 1066 if (hval >= db->hsize) 1067 hval -= db->hsize; 1068 dictp = &db->dict[hval]; 1069 } while (dictp->codem1 < max_ent); 1070 } 1071 1072 /* 1073 * Invalidate previous hash table entry 1074 * assigned this code, and then take it over 1075 */ 1076 dictp2 = &db->dict[max_ent+1]; 1077 if (db->dict[dictp2->cptr].codem1 == max_ent) { 1078 db->dict[dictp2->cptr].codem1 = BADCODEM1; 1079 } 1080 dictp2->cptr = hval; 1081 dictp->codem1 = max_ent; 1082 dictp->f.fcode = fcode; 1083 1084 db->max_ent = ++max_ent; 1085 db->lens[max_ent] = db->lens[oldcode]+1; 1086 1087 /* Expand code size if needed. */ 1088 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { 1089 db->n_bits = ++n_bits; 1090 tgtbitno = 32-n_bits; 1091 } 1092 } 1093 oldcode = incode; 1094 } 1095 dmsg->b_wptr = wptr; 1096 1097 /* 1098 * Keep the checkpoint right so that incompressible packets 1099 * clear the dictionary at the right times. 1100 */ 1101 db->bytes_out += ilen; 1102 db->in_count += explen; 1103 if (bsd_check(db) && db->debug) { 1104 printf("bsd_decomp%d: peer should have cleared dictionary\n", 1105 db->unit); 1106 } 1107 1108 ++db->comp_count; 1109 db->comp_bytes += ilen + BSD_OVHD; 1110 ++db->uncomp_count; 1111 db->uncomp_bytes += explen; 1112 1113 *dmpp = mret; 1114 return DECOMP_OK; 1115} 1116#endif /* DO_BSD_COMPRESS */ 1117