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 1.21 2004/01/17 05:47:55 carlsonj 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#ifdef SOL2 70#include <sys/sunddi.h> 71#endif 72 73#define PACKETPTR mblk_t * 74#include <net/ppp-comp.h> 75 76#if DO_BSD_COMPRESS 77 78/* 79 * PPP "BSD compress" compression 80 * The differences between this compression and the classic BSD LZW 81 * source are obvious from the requirement that the classic code worked 82 * with files while this handles arbitrarily long streams that 83 * are broken into packets. They are: 84 * 85 * When the code size expands, a block of junk is not emitted by 86 * the compressor and not expected by the decompressor. 87 * 88 * New codes are not necessarily assigned every time an old 89 * code is output by the compressor. This is because a packet 90 * end forces a code to be emitted, but does not imply that a 91 * new sequence has been seen. 92 * 93 * The compression ratio is checked at the first end of a packet 94 * after the appropriate gap. Besides simplifying and speeding 95 * things up, this makes it more likely that the transmitter 96 * and receiver will agree when the dictionary is cleared when 97 * compression is not going well. 98 */ 99 100/* 101 * A dictionary for doing BSD compress. 102 */ 103struct bsd_db { 104 int totlen; /* length of this structure */ 105 u_int hsize; /* size of the hash table */ 106 u_char hshift; /* used in hash function */ 107 u_char n_bits; /* current bits/code */ 108 u_char maxbits; 109 u_char debug; 110 u_char unit; 111 u_short seqno; /* sequence number of next packet */ 112 u_int hdrlen; /* header length to preallocate */ 113 u_int mru; 114 u_int maxmaxcode; /* largest valid code */ 115 u_int max_ent; /* largest code in use */ 116 u_int in_count; /* uncompressed bytes, aged */ 117 u_int bytes_out; /* compressed bytes, aged */ 118 u_int ratio; /* recent compression ratio */ 119 u_int checkpoint; /* when to next check the ratio */ 120 u_int clear_count; /* times dictionary cleared */ 121 u_int incomp_count; /* incompressible packets */ 122 u_int incomp_bytes; /* incompressible bytes */ 123 u_int uncomp_count; /* uncompressed packets */ 124 u_int uncomp_bytes; /* uncompressed bytes */ 125 u_int comp_count; /* compressed packets */ 126 u_int comp_bytes; /* compressed bytes */ 127 u_short *lens; /* array of lengths of codes */ 128 struct bsd_dict { 129 union { /* hash value */ 130 u_int32_t fcode; 131 struct { 132#ifdef BSD_LITTLE_ENDIAN 133 u_short prefix; /* preceding code */ 134 u_char suffix; /* last character of new code */ 135 u_char pad; 136#else 137 u_char pad; 138 u_char suffix; /* last character of new code */ 139 u_short prefix; /* preceding code */ 140#endif 141 } hs; 142 } f; 143 u_short codem1; /* output of hash table -1 */ 144 u_short cptr; /* map code to hash table entry */ 145 } dict[1]; 146}; 147 148#define BSD_OVHD 2 /* BSD compress overhead/packet */ 149#define BSD_INIT_BITS BSD_MIN_BITS 150 151static void *bsd_comp_alloc __P((u_char *options, int opt_len)); 152static void *bsd_decomp_alloc __P((u_char *options, int opt_len)); 153static void bsd_free __P((void *state)); 154static int bsd_comp_init __P((void *state, u_char *options, int opt_len, 155 int unit, int hdrlen, int debug)); 156static int bsd_decomp_init __P((void *state, u_char *options, int opt_len, 157 int unit, int hdrlen, int mru, int debug)); 158static int bsd_compress __P((void *state, mblk_t **mret, 159 mblk_t *mp, int slen, int maxolen)); 160static void bsd_incomp __P((void *state, mblk_t *dmsg)); 161static int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp)); 162static void bsd_reset __P((void *state)); 163static void bsd_comp_stats __P((void *state, struct compstat *stats)); 164 165/* 166 * Procedures exported to ppp_comp.c. 167 */ 168struct compressor ppp_bsd_compress = { 169 CI_BSD_COMPRESS, /* compress_proto */ 170 bsd_comp_alloc, /* comp_alloc */ 171 bsd_free, /* comp_free */ 172 bsd_comp_init, /* comp_init */ 173 bsd_reset, /* comp_reset */ 174 bsd_compress, /* compress */ 175 bsd_comp_stats, /* comp_stat */ 176 bsd_decomp_alloc, /* decomp_alloc */ 177 bsd_free, /* decomp_free */ 178 bsd_decomp_init, /* decomp_init */ 179 bsd_reset, /* decomp_reset */ 180 bsd_decompress, /* decompress */ 181 bsd_incomp, /* incomp */ 182 bsd_comp_stats, /* decomp_stat */ 183}; 184 185/* 186 * the next two codes should not be changed lightly, as they must not 187 * lie within the contiguous general code space. 188 */ 189#define CLEAR 256 /* table clear output code */ 190#define FIRST 257 /* first free entry */ 191#define LAST 255 192 193#define MAXCODE(b) ((1 << (b)) - 1) 194#define BADCODEM1 MAXCODE(BSD_MAX_BITS) 195 196#define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \ 197 ^ (u_int32_t)(prefix)) 198#define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \ 199 + (u_int32_t)(prefix)) 200 201#define CHECK_GAP 10000 /* Ratio check interval */ 202 203#define RATIO_SCALE_LOG 8 204#define RATIO_SCALE (1<<RATIO_SCALE_LOG) 205#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) 206 207#define DECOMP_CHUNK 256 208 209/* 210 * clear the dictionary 211 */ 212static void 213bsd_clear(db) 214 struct bsd_db *db; 215{ 216 db->clear_count++; 217 db->max_ent = FIRST-1; 218 db->n_bits = BSD_INIT_BITS; 219 db->ratio = 0; 220 db->bytes_out = 0; 221 db->in_count = 0; 222 db->checkpoint = CHECK_GAP; 223} 224 225/* 226 * If the dictionary is full, then see if it is time to reset it. 227 * 228 * Compute the compression ratio using fixed-point arithmetic 229 * with 8 fractional bits. 230 * 231 * Since we have an infinite stream instead of a single file, 232 * watch only the local compression ratio. 233 * 234 * Since both peers must reset the dictionary at the same time even in 235 * the absence of CLEAR codes (while packets are incompressible), they 236 * must compute the same ratio. 237 */ 238static int /* 1=output CLEAR */ 239bsd_check(db) 240 struct bsd_db *db; 241{ 242 u_int new_ratio; 243 244 if (db->in_count >= db->checkpoint) { 245 /* age the ratio by limiting the size of the counts */ 246 if (db->in_count >= RATIO_MAX 247 || db->bytes_out >= RATIO_MAX) { 248 db->in_count -= db->in_count/4; 249 db->bytes_out -= db->bytes_out/4; 250 } 251 252 db->checkpoint = db->in_count + CHECK_GAP; 253 254 if (db->max_ent >= db->maxmaxcode) { 255 /* Reset the dictionary only if the ratio is worse, 256 * or if it looks as if it has been poisoned 257 * by incompressible data. 258 * 259 * This does not overflow, because 260 * db->in_count <= RATIO_MAX. 261 */ 262 new_ratio = db->in_count << RATIO_SCALE_LOG; 263 if (db->bytes_out != 0) 264 new_ratio /= db->bytes_out; 265 266 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) { 267 bsd_clear(db); 268 return 1; 269 } 270 db->ratio = new_ratio; 271 } 272 } 273 return 0; 274} 275 276/* 277 * Return statistics. 278 */ 279static void 280bsd_comp_stats(state, stats) 281 void *state; 282 struct compstat *stats; 283{ 284 struct bsd_db *db = (struct bsd_db *) state; 285 u_int out; 286 287 stats->unc_bytes = db->uncomp_bytes; 288 stats->unc_packets = db->uncomp_count; 289 stats->comp_bytes = db->comp_bytes; 290 stats->comp_packets = db->comp_count; 291 stats->inc_bytes = db->incomp_bytes; 292 stats->inc_packets = db->incomp_count; 293 stats->ratio = db->in_count; 294 out = db->bytes_out; 295 if (stats->ratio <= 0x7fffff) 296 stats->ratio <<= 8; 297 else 298 out >>= 8; 299 if (out != 0) 300 stats->ratio /= out; 301} 302 303/* 304 * Reset state, as on a CCP ResetReq. 305 */ 306static void 307bsd_reset(state) 308 void *state; 309{ 310 struct bsd_db *db = (struct bsd_db *) state; 311 312 db->seqno = 0; 313 bsd_clear(db); 314 db->clear_count = 0; 315} 316 317/* 318 * Allocate space for a (de) compressor. 319 */ 320static void * 321bsd_alloc(options, opt_len, decomp) 322 u_char *options; 323 int opt_len, decomp; 324{ 325 int bits; 326 u_int newlen, hsize, hshift, maxmaxcode; 327 struct bsd_db *db; 328 329 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3 330 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) 331 return NULL; 332 333 bits = BSD_NBITS(options[2]); 334 switch (bits) { 335 case 9: /* needs 82152 for both directions */ 336 case 10: /* needs 84144 */ 337 case 11: /* needs 88240 */ 338 case 12: /* needs 96432 */ 339 hsize = 5003; 340 hshift = 4; 341 break; 342 case 13: /* needs 176784 */ 343 hsize = 9001; 344 hshift = 5; 345 break; 346 case 14: /* needs 353744 */ 347 hsize = 18013; 348 hshift = 6; 349 break; 350 case 15: /* needs 691440 */ 351 hsize = 35023; 352 hshift = 7; 353 break; 354 case 16: /* needs 1366160--far too much, */ 355 /* hsize = 69001; */ /* and 69001 is too big for cptr */ 356 /* hshift = 8; */ /* in struct bsd_db */ 357 /* break; */ 358 default: 359 return NULL; 360 } 361 362 maxmaxcode = MAXCODE(bits); 363 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0])); 364#ifdef __osf__ 365 db = (struct bsd_db *) ALLOC_SLEEP(newlen); 366#else 367 db = (struct bsd_db *) ALLOC_NOSLEEP(newlen); 368#endif 369 if (!db) 370 return NULL; 371 bzero(db, sizeof(*db) - sizeof(db->dict)); 372 373 if (!decomp) { 374 db->lens = NULL; 375 } else { 376#ifdef __osf__ 377 db->lens = (u_short *) ALLOC_SLEEP((maxmaxcode+1) * sizeof(db->lens[0])); 378#else 379 db->lens = (u_short *) ALLOC_NOSLEEP((maxmaxcode+1) * sizeof(db->lens[0])); 380#endif 381 if (!db->lens) { 382 FREE(db, newlen); 383 return NULL; 384 } 385 } 386 387 db->totlen = newlen; 388 db->hsize = hsize; 389 db->hshift = hshift; 390 db->maxmaxcode = maxmaxcode; 391 db->maxbits = bits; 392 393 return (void *) db; 394} 395 396static void 397bsd_free(state) 398 void *state; 399{ 400 struct bsd_db *db = (struct bsd_db *) state; 401 402 if (db->lens) 403 FREE(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0])); 404 FREE(db, db->totlen); 405} 406 407static void * 408bsd_comp_alloc(options, opt_len) 409 u_char *options; 410 int opt_len; 411{ 412 return bsd_alloc(options, opt_len, 0); 413} 414 415static void * 416bsd_decomp_alloc(options, opt_len) 417 u_char *options; 418 int opt_len; 419{ 420 return bsd_alloc(options, opt_len, 1); 421} 422 423/* 424 * Initialize the database. 425 */ 426static int 427bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp) 428 struct bsd_db *db; 429 u_char *options; 430 int opt_len, unit, hdrlen, mru, debug, decomp; 431{ 432 int i; 433 434 if (opt_len < CILEN_BSD_COMPRESS 435 || options[0] != CI_BSD_COMPRESS || options[1] != CILEN_BSD_COMPRESS 436 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION 437 || BSD_NBITS(options[2]) != db->maxbits 438 || decomp && db->lens == NULL) 439 return 0; 440 441 if (decomp) { 442 i = LAST+1; 443 while (i != 0) 444 db->lens[--i] = 1; 445 } 446 i = db->hsize; 447 while (i != 0) { 448 db->dict[--i].codem1 = BADCODEM1; 449 db->dict[i].cptr = 0; 450 } 451 452 db->unit = unit; 453 db->hdrlen = hdrlen; 454 db->mru = mru; 455 if (debug) 456 db->debug = 1; 457 458 bsd_reset(db); 459 460 return 1; 461} 462 463static int 464bsd_comp_init(state, options, opt_len, unit, hdrlen, debug) 465 void *state; 466 u_char *options; 467 int opt_len, unit, hdrlen, debug; 468{ 469 return bsd_init((struct bsd_db *) state, options, opt_len, 470 unit, hdrlen, 0, debug, 0); 471} 472 473static int 474bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug) 475 void *state; 476 u_char *options; 477 int opt_len, unit, hdrlen, mru, debug; 478{ 479 return bsd_init((struct bsd_db *) state, options, opt_len, 480 unit, hdrlen, mru, debug, 1); 481} 482 483 484/* 485 * compress a packet 486 * One change from the BSD compress command is that when the 487 * code size expands, we do not output a bunch of padding. 488 * 489 * N.B. at present, we ignore the hdrlen specified in the comp_init call. 490 */ 491static int /* new slen */ 492bsd_compress(state, mretp, mp, slen, maxolen) 493 void *state; 494 mblk_t **mretp; /* return compressed mbuf chain here */ 495 mblk_t *mp; /* from here */ 496 int slen; /* uncompressed length */ 497 int maxolen; /* max compressed length */ 498{ 499 struct bsd_db *db = (struct bsd_db *) state; 500 int hshift = db->hshift; 501 u_int max_ent = db->max_ent; 502 u_int n_bits = db->n_bits; 503 u_int bitno = 32; 504 u_int32_t accm = 0, fcode; 505 struct bsd_dict *dictp; 506 u_char c; 507 int hval, disp, ent, ilen; 508 mblk_t *np, *mret; 509 u_char *rptr, *wptr; 510 u_char *cp_end; 511 int olen; 512 mblk_t *m, **mnp; 513 514#define PUTBYTE(v) { \ 515 if (wptr) { \ 516 *wptr++ = (v); \ 517 if (wptr >= cp_end) { \ 518 m->b_wptr = wptr; \ 519 m = m->b_cont; \ 520 if (m) { \ 521 wptr = m->b_wptr; \ 522 cp_end = m->b_datap->db_lim; \ 523 } else \ 524 wptr = NULL; \ 525 } \ 526 } \ 527 ++olen; \ 528} 529 530#define OUTPUT(ent) { \ 531 bitno -= n_bits; \ 532 accm |= ((ent) << bitno); \ 533 do { \ 534 PUTBYTE(accm >> 24); \ 535 accm <<= 8; \ 536 bitno += 8; \ 537 } while (bitno <= 24); \ 538} 539 540 /* 541 * First get the protocol and check that we're 542 * interested in this packet. 543 */ 544 *mretp = NULL; 545 rptr = mp->b_rptr; 546 if (rptr + PPP_HDRLEN > mp->b_wptr) { 547 if (!pullupmsg(mp, PPP_HDRLEN)) 548 return 0; 549 rptr = mp->b_rptr; 550 } 551 ent = PPP_PROTOCOL(rptr); /* get the protocol */ 552 if (ent < 0x21 || ent > 0xf9) 553 return 0; 554 555 /* Don't generate compressed packets which are larger than 556 the uncompressed packet. */ 557 if (maxolen > slen) 558 maxolen = slen; 559 560 /* Allocate enough message blocks to give maxolen total space. */ 561 mnp = &mret; 562 for (olen = maxolen; olen > 0; ) { 563 m = allocb((olen < 4096? olen: 4096), BPRI_MED); 564 *mnp = m; 565 if (m == NULL) { 566 if (mret != NULL) { 567 freemsg(mret); 568 mnp = &mret; 569 } 570 break; 571 } 572 mnp = &m->b_cont; 573 olen -= m->b_datap->db_lim - m->b_wptr; 574 } 575 *mnp = NULL; 576 577 if ((m = mret) != NULL) { 578 wptr = m->b_wptr; 579 cp_end = m->b_datap->db_lim; 580 } else 581 wptr = cp_end = NULL; 582 olen = 0; 583 584 /* 585 * Copy the PPP header over, changing the protocol, 586 * and install the 2-byte sequence number. 587 */ 588 if (wptr) { 589 wptr[0] = PPP_ADDRESS(rptr); 590 wptr[1] = PPP_CONTROL(rptr); 591 wptr[2] = 0; /* change the protocol */ 592 wptr[3] = PPP_COMP; 593 wptr[4] = db->seqno >> 8; 594 wptr[5] = db->seqno; 595 wptr += PPP_HDRLEN + BSD_OVHD; 596 } 597 ++db->seqno; 598 rptr += PPP_HDRLEN; 599 600 slen = mp->b_wptr - rptr; 601 ilen = slen + 1; 602 np = mp->b_cont; 603 for (;;) { 604 if (slen <= 0) { 605 if (!np) 606 break; 607 rptr = np->b_rptr; 608 slen = np->b_wptr - rptr; 609 np = np->b_cont; 610 if (!slen) 611 continue; /* handle 0-length buffers */ 612 ilen += slen; 613 } 614 615 slen--; 616 c = *rptr++; 617 fcode = BSD_KEY(ent, c); 618 hval = BSD_HASH(ent, c, hshift); 619 dictp = &db->dict[hval]; 620 621 /* Validate and then check the entry. */ 622 if (dictp->codem1 >= max_ent) 623 goto nomatch; 624 if (dictp->f.fcode == fcode) { 625 ent = dictp->codem1+1; 626 continue; /* found (prefix,suffix) */ 627 } 628 629 /* continue probing until a match or invalid entry */ 630 disp = (hval == 0) ? 1 : hval; 631 do { 632 hval += disp; 633 if (hval >= db->hsize) 634 hval -= db->hsize; 635 dictp = &db->dict[hval]; 636 if (dictp->codem1 >= max_ent) 637 goto nomatch; 638 } while (dictp->f.fcode != fcode); 639 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ 640 continue; 641 642 nomatch: 643 OUTPUT(ent); /* output the prefix */ 644 645 /* code -> hashtable */ 646 if (max_ent < db->maxmaxcode) { 647 struct bsd_dict *dictp2; 648 /* expand code size if needed */ 649 if (max_ent >= MAXCODE(n_bits)) 650 db->n_bits = ++n_bits; 651 652 /* Invalidate old hash table entry using 653 * this code, and then take it over. 654 */ 655 dictp2 = &db->dict[max_ent+1]; 656 if (db->dict[dictp2->cptr].codem1 == max_ent) 657 db->dict[dictp2->cptr].codem1 = BADCODEM1; 658 dictp2->cptr = hval; 659 dictp->codem1 = max_ent; 660 dictp->f.fcode = fcode; 661 662 db->max_ent = ++max_ent; 663 } 664 ent = c; 665 } 666 667 OUTPUT(ent); /* output the last code */ 668 db->bytes_out += olen; 669 db->in_count += ilen; 670 if (bitno < 32) 671 ++db->bytes_out; /* count complete bytes */ 672 673 if (bsd_check(db)) 674 OUTPUT(CLEAR); /* do not count the CLEAR */ 675 676 /* 677 * Pad dribble bits of last code with ones. 678 * Do not emit a completely useless byte of ones. 679 */ 680 if (bitno != 32) 681 PUTBYTE((accm | (0xff << (bitno-8))) >> 24); 682 683 /* 684 * Increase code size if we would have without the packet 685 * boundary and as the decompressor will. 686 */ 687 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) 688 db->n_bits++; 689 690 db->uncomp_bytes += ilen; 691 ++db->uncomp_count; 692 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) { 693 /* throw away the compressed stuff if it is longer than uncompressed */ 694 freemsg(mret); 695 mret = NULL; 696 ++db->incomp_count; 697 db->incomp_bytes += ilen; 698 } else if (wptr != NULL) { 699 m->b_wptr = wptr; 700 if (m->b_cont) { 701 freemsg(m->b_cont); 702 m->b_cont = NULL; 703 } 704 ++db->comp_count; 705 db->comp_bytes += olen + BSD_OVHD; 706 } 707 708 *mretp = mret; 709 return olen + PPP_HDRLEN + BSD_OVHD; 710#undef OUTPUT 711#undef PUTBYTE 712} 713 714 715/* 716 * Update the "BSD Compress" dictionary on the receiver for 717 * incompressible data by pretending to compress the incoming data. 718 */ 719static void 720bsd_incomp(state, dmsg) 721 void *state; 722 mblk_t *dmsg; 723{ 724 struct bsd_db *db = (struct bsd_db *) state; 725 u_int hshift = db->hshift; 726 u_int max_ent = db->max_ent; 727 u_int n_bits = db->n_bits; 728 struct bsd_dict *dictp; 729 u_int32_t fcode; 730 u_char c; 731 long hval, disp; 732 int slen, ilen; 733 u_int bitno = 7; 734 u_char *rptr; 735 u_int ent; 736 737 rptr = dmsg->b_rptr; 738 if (rptr + PPP_HDRLEN > dmsg->b_wptr) { 739 if (!pullupmsg(dmsg, PPP_HDRLEN)) 740 return; 741 rptr = dmsg->b_rptr; 742 } 743 ent = PPP_PROTOCOL(rptr); /* get the protocol */ 744 if (ent < 0x21 || ent > 0xf9) 745 return; 746 747 db->seqno++; 748 ilen = 1; /* count the protocol as 1 byte */ 749 rptr += PPP_HDRLEN; 750 for (;;) { 751 slen = dmsg->b_wptr - rptr; 752 if (slen <= 0) { 753 dmsg = dmsg->b_cont; 754 if (!dmsg) 755 break; 756 rptr = dmsg->b_rptr; 757 continue; /* skip zero-length buffers */ 758 } 759 ilen += slen; 760 761 do { 762 c = *rptr++; 763 fcode = BSD_KEY(ent, c); 764 hval = BSD_HASH(ent, c, hshift); 765 dictp = &db->dict[hval]; 766 767 /* validate and then check the entry */ 768 if (dictp->codem1 >= max_ent) 769 goto nomatch; 770 if (dictp->f.fcode == fcode) { 771 ent = dictp->codem1+1; 772 continue; /* found (prefix,suffix) */ 773 } 774 775 /* continue probing until a match or invalid entry */ 776 disp = (hval == 0) ? 1 : hval; 777 do { 778 hval += disp; 779 if (hval >= db->hsize) 780 hval -= db->hsize; 781 dictp = &db->dict[hval]; 782 if (dictp->codem1 >= max_ent) 783 goto nomatch; 784 } while (dictp->f.fcode != fcode); 785 ent = dictp->codem1+1; 786 continue; /* finally found (prefix,suffix) */ 787 788 nomatch: /* output (count) the prefix */ 789 bitno += n_bits; 790 791 /* code -> hashtable */ 792 if (max_ent < db->maxmaxcode) { 793 struct bsd_dict *dictp2; 794 /* expand code size if needed */ 795 if (max_ent >= MAXCODE(n_bits)) 796 db->n_bits = ++n_bits; 797 798 /* Invalidate previous hash table entry 799 * assigned this code, and then take it over. 800 */ 801 dictp2 = &db->dict[max_ent+1]; 802 if (db->dict[dictp2->cptr].codem1 == max_ent) 803 db->dict[dictp2->cptr].codem1 = BADCODEM1; 804 dictp2->cptr = hval; 805 dictp->codem1 = max_ent; 806 dictp->f.fcode = fcode; 807 808 db->max_ent = ++max_ent; 809 db->lens[max_ent] = db->lens[ent]+1; 810 } 811 ent = c; 812 } while (--slen != 0); 813 } 814 bitno += n_bits; /* output (count) the last code */ 815 db->bytes_out += bitno/8; 816 db->in_count += ilen; 817 (void)bsd_check(db); 818 819 ++db->incomp_count; 820 db->incomp_bytes += ilen; 821 ++db->uncomp_count; 822 db->uncomp_bytes += ilen; 823 824 /* Increase code size if we would have without the packet 825 * boundary and as the decompressor will. 826 */ 827 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) 828 db->n_bits++; 829} 830 831 832/* 833 * Decompress "BSD Compress" 834 * 835 * Because of patent problems, we return DECOMP_ERROR for errors 836 * found by inspecting the input data and for system problems, but 837 * DECOMP_FATALERROR for any errors which could possibly be said to 838 * be being detected "after" decompression. For DECOMP_ERROR, 839 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be 840 * infringing a patent of Motorola's if we do, so we take CCP down 841 * instead. 842 * 843 * Given that the frame has the correct sequence number and a good FCS, 844 * errors such as invalid codes in the input most likely indicate a 845 * bug, so we return DECOMP_FATALERROR for them in order to turn off 846 * compression, even though they are detected by inspecting the input. 847 */ 848static int 849bsd_decompress(state, cmsg, dmpp) 850 void *state; 851 mblk_t *cmsg, **dmpp; 852{ 853 struct bsd_db *db = (struct bsd_db *) state; 854 u_int max_ent = db->max_ent; 855 u_int32_t accm = 0; 856 u_int bitno = 32; /* 1st valid bit in accm */ 857 u_int n_bits = db->n_bits; 858 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */ 859 struct bsd_dict *dictp; 860 int explen, i, seq, len; 861 u_int incode, oldcode, finchar; 862 u_char *p, *rptr, *wptr; 863 mblk_t *dmsg, *mret; 864 int adrs, ctrl, ilen; 865 int dlen, space, codelen, extra; 866 867 /* 868 * Get at least the BSD Compress header in the first buffer 869 */ 870 rptr = cmsg->b_rptr; 871 if (rptr + PPP_HDRLEN + BSD_OVHD >= cmsg->b_wptr) { 872 if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) { 873 if (db->debug) 874 printf("bsd_decomp%d: failed to pullup\n", db->unit); 875 return DECOMP_ERROR; 876 } 877 rptr = cmsg->b_rptr; 878 } 879 880 /* 881 * Save the address/control from the PPP header 882 * and then get the sequence number. 883 */ 884 adrs = PPP_ADDRESS(rptr); 885 ctrl = PPP_CONTROL(rptr); 886 rptr += PPP_HDRLEN; 887 seq = (rptr[0] << 8) + rptr[1]; 888 rptr += BSD_OVHD; 889 ilen = len = cmsg->b_wptr - rptr; 890 891 /* 892 * Check the sequence number and give up if it is not what we expect. 893 */ 894 if (seq != db->seqno++) { 895 if (db->debug) 896 printf("bsd_decomp%d: bad sequence # %d, expected %d\n", 897 db->unit, seq, db->seqno - 1); 898 return DECOMP_ERROR; 899 } 900 901 /* 902 * Allocate one message block to start with. 903 */ 904 if ((dmsg = allocb(DECOMP_CHUNK + db->hdrlen, BPRI_MED)) == NULL) 905 return DECOMP_ERROR; 906 mret = dmsg; 907 dmsg->b_wptr += db->hdrlen; 908 dmsg->b_rptr = wptr = dmsg->b_wptr; 909 910 /* Fill in the ppp header, but not the last byte of the protocol 911 (that comes from the decompressed data). */ 912 wptr[0] = adrs; 913 wptr[1] = ctrl; 914 wptr[2] = 0; 915 wptr += PPP_HDRLEN - 1; 916 space = dmsg->b_datap->db_lim - wptr; 917 918 oldcode = CLEAR; 919 explen = 0; 920 for (;;) { 921 if (len == 0) { 922 cmsg = cmsg->b_cont; 923 if (!cmsg) /* quit at end of message */ 924 break; 925 rptr = cmsg->b_rptr; 926 len = cmsg->b_wptr - rptr; 927 ilen += len; 928 continue; /* handle 0-length buffers */ 929 } 930 931 /* 932 * Accumulate bytes until we have a complete code. 933 * Then get the next code, relying on the 32-bit, 934 * unsigned accm to mask the result. 935 */ 936 bitno -= 8; 937 accm |= *rptr++ << bitno; 938 --len; 939 if (tgtbitno < bitno) 940 continue; 941 incode = accm >> tgtbitno; 942 accm <<= n_bits; 943 bitno += n_bits; 944 945 if (incode == CLEAR) { 946 /* 947 * The dictionary must only be cleared at 948 * the end of a packet. But there could be an 949 * empty message block at the end. 950 */ 951 if (len > 0 || cmsg->b_cont != 0) { 952 if (cmsg->b_cont) 953 len += msgdsize(cmsg->b_cont); 954 if (len > 0) { 955 freemsg(dmsg); 956 if (db->debug) 957 printf("bsd_decomp%d: bad CLEAR\n", db->unit); 958 return DECOMP_FATALERROR; 959 } 960 } 961 bsd_clear(db); 962 explen = ilen = 0; 963 break; 964 } 965 966 if (incode > max_ent + 2 || incode > db->maxmaxcode 967 || incode > max_ent && oldcode == CLEAR) { 968 freemsg(dmsg); 969 if (db->debug) { 970 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", 971 db->unit, incode, oldcode); 972 printf("max_ent=0x%x dlen=%d seqno=%d\n", 973 max_ent, dlen, db->seqno); 974 } 975 return DECOMP_FATALERROR; /* probably a bug */ 976 } 977 978 /* Special case for KwKwK string. */ 979 if (incode > max_ent) { 980 finchar = oldcode; 981 extra = 1; 982 } else { 983 finchar = incode; 984 extra = 0; 985 } 986 987 codelen = db->lens[finchar]; 988 explen += codelen + extra; 989 if (explen > db->mru + 1) { 990 freemsg(dmsg); 991 if (db->debug) 992 printf("bsd_decomp%d: ran out of mru\n", db->unit); 993 return DECOMP_FATALERROR; 994 } 995 996 /* 997 * Decode this code and install it in the decompressed buffer. 998 */ 999 space -= codelen + extra; 1000 if (space < 0) { 1001 /* Allocate another message block. */ 1002 dmsg->b_wptr = wptr; 1003 dlen = codelen + extra; 1004 if (dlen < DECOMP_CHUNK) 1005 dlen = DECOMP_CHUNK; 1006 if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) { 1007 freemsg(dmsg); 1008 return DECOMP_ERROR; 1009 } 1010 dmsg = dmsg->b_cont; 1011 wptr = dmsg->b_wptr; 1012 space = dmsg->b_datap->db_lim - wptr - codelen - extra; 1013 } 1014 p = (wptr += codelen); 1015 while (finchar > LAST) { 1016 dictp = &db->dict[db->dict[finchar].cptr]; 1017#ifdef DEBUG 1018 --codelen; 1019 if (codelen <= 0) { 1020 freemsg(dmsg); 1021 printf("bsd_decomp%d: fell off end of chain ", db->unit); 1022 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", 1023 incode, finchar, db->dict[finchar].cptr, max_ent); 1024 return DECOMP_FATALERROR; 1025 } 1026 if (dictp->codem1 != finchar-1) { 1027 freemsg(dmsg); 1028 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", 1029 db->unit, incode, finchar); 1030 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, 1031 db->dict[finchar].cptr, dictp->codem1); 1032 return DECOMP_FATALERROR; 1033 } 1034#endif 1035 *--p = dictp->f.hs.suffix; 1036 finchar = dictp->f.hs.prefix; 1037 } 1038 *--p = finchar; 1039 1040#ifdef DEBUG 1041 if (--codelen != 0) 1042 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", 1043 db->unit, codelen, incode, max_ent); 1044#endif 1045 1046 if (extra) /* the KwKwK case again */ 1047 *wptr++ = finchar; 1048 1049 /* 1050 * If not first code in a packet, and 1051 * if not out of code space, then allocate a new code. 1052 * 1053 * Keep the hash table correct so it can be used 1054 * with uncompressed packets. 1055 */ 1056 if (oldcode != CLEAR && max_ent < db->maxmaxcode) { 1057 struct bsd_dict *dictp2; 1058 u_int32_t fcode; 1059 int hval, disp; 1060 1061 fcode = BSD_KEY(oldcode,finchar); 1062 hval = BSD_HASH(oldcode,finchar,db->hshift); 1063 dictp = &db->dict[hval]; 1064 1065 /* look for a free hash table entry */ 1066 if (dictp->codem1 < max_ent) { 1067 disp = (hval == 0) ? 1 : hval; 1068 do { 1069 hval += disp; 1070 if (hval >= db->hsize) 1071 hval -= db->hsize; 1072 dictp = &db->dict[hval]; 1073 } while (dictp->codem1 < max_ent); 1074 } 1075 1076 /* 1077 * Invalidate previous hash table entry 1078 * assigned this code, and then take it over 1079 */ 1080 dictp2 = &db->dict[max_ent+1]; 1081 if (db->dict[dictp2->cptr].codem1 == max_ent) { 1082 db->dict[dictp2->cptr].codem1 = BADCODEM1; 1083 } 1084 dictp2->cptr = hval; 1085 dictp->codem1 = max_ent; 1086 dictp->f.fcode = fcode; 1087 1088 db->max_ent = ++max_ent; 1089 db->lens[max_ent] = db->lens[oldcode]+1; 1090 1091 /* Expand code size if needed. */ 1092 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { 1093 db->n_bits = ++n_bits; 1094 tgtbitno = 32-n_bits; 1095 } 1096 } 1097 oldcode = incode; 1098 } 1099 dmsg->b_wptr = wptr; 1100 1101 /* 1102 * Keep the checkpoint right so that incompressible packets 1103 * clear the dictionary at the right times. 1104 */ 1105 db->bytes_out += ilen; 1106 db->in_count += explen; 1107 if (bsd_check(db) && db->debug) { 1108 printf("bsd_decomp%d: peer should have cleared dictionary\n", 1109 db->unit); 1110 } 1111 1112 ++db->comp_count; 1113 db->comp_bytes += ilen + BSD_OVHD; 1114 ++db->uncomp_count; 1115 db->uncomp_bytes += explen; 1116 1117 *dmpp = mret; 1118 return DECOMP_OK; 1119} 1120#endif /* DO_BSD_COMPRESS */ 1121