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 * $Id: bsd-comp.c,v 1.3 1999/04/16 11:35:59 paulus Exp $ 42 */ 43 44 #include <sys/types.h> 45 #include <stddef.h> 46 #include <stdlib.h> 47 #ifdef PPP_DEFS_IN_NET 48 #include <net/ppp_defs.h> 49 #else 50 #include "ppp_defs.h" 51 #endif 52 #include "ppp-comp.h" 53 54 #if DO_BSD_COMPRESS 55 56 /* 57 * PPP "BSD compress" compression 58 * The differences between this compression and the classic BSD LZW 59 * source are obvious from the requirement that the classic code worked 60 * with files while this handles arbitrarily long streams that 61 * are broken into packets. They are: 62 * 63 * When the code size expands, a block of junk is not emitted by 64 * the compressor and not expected by the decompressor. 65 * 66 * New codes are not necessarily assigned every time an old 67 * code is output by the compressor. This is because a packet 68 * end forces a code to be emitted, but does not imply that a 69 * new sequence has been seen. 70 * 71 * The compression ratio is checked at the first end of a packet 72 * after the appropriate gap. Besides simplifying and speeding 73 * things up, this makes it more likely that the transmitter 74 * and receiver will agree when the dictionary is cleared when 75 * compression is not going well. 76 */ 77 78 /* 79 * A dictionary for doing BSD compress. 80 */ 81 struct bsd_db { 82 int totlen; /* length of this structure */ 83 u_int hsize; /* size of the hash table */ 84 u_char hshift; /* used in hash function */ 85 u_char n_bits; /* current bits/code */ 86 u_char maxbits; 87 u_char debug; 88 u_char unit; 89 u_short seqno; /* sequence number of next packet */ 90 u_int hdrlen; /* header length to preallocate */ 91 u_int mru; 92 u_int maxmaxcode; /* largest valid code */ 93 u_int max_ent; /* largest code in use */ 94 u_int in_count; /* uncompressed bytes, aged */ 95 u_int bytes_out; /* compressed bytes, aged */ 96 u_int ratio; /* recent compression ratio */ 97 u_int checkpoint; /* when to next check the ratio */ 98 u_int clear_count; /* times dictionary cleared */ 99 u_int incomp_count; /* incompressible packets */ 100 u_int incomp_bytes; /* incompressible bytes */ 101 u_int uncomp_count; /* uncompressed packets */ 102 u_int uncomp_bytes; /* uncompressed bytes */ 103 u_int comp_count; /* compressed packets */ 104 u_int comp_bytes; /* compressed bytes */ 105 u_short *lens; /* array of lengths of codes */ 106 struct bsd_dict { 107 union { /* hash value */ 108 u_int32_t fcode; 109 struct { 110 #ifdef BSD_LITTLE_ENDIAN 111 u_short prefix; /* preceding code */ 112 u_char suffix; /* last character of new code */ 113 u_char pad; 114 #else 115 u_char pad; 116 u_char suffix; /* last character of new code */ 117 u_short prefix; /* preceding code */ 118 #endif 119 } hs; 120 } f; 121 u_short codem1; /* output of hash table -1 */ 122 u_short cptr; /* map code to hash table entry */ 123 } dict[1]; 124 }; 125 126 #define BSD_OVHD 2 /* BSD compress overhead/packet */ 127 #define BSD_INIT_BITS BSD_MIN_BITS 128 129 static void *bsd_decomp_alloc __P((u_char *options, int opt_len)); 130 static void bsd_free __P((void *state)); 131 static int bsd_decomp_init __P((void *state, u_char *options, int opt_len, 132 int unit, int hdrlen, int mru, int debug)); 133 static void bsd_incomp __P((void *state, u_char *dmsg, int len)); 134 static int bsd_decompress __P((void *state, u_char *cmp, int inlen, 135 u_char *dmp, int *outlen)); 136 static void bsd_reset __P((void *state)); 137 static void bsd_comp_stats __P((void *state, struct compstat *stats)); 138 139 /* 140 * Exported procedures. 141 */ 142 struct compressor ppp_bsd_compress = { 143 CI_BSD_COMPRESS, /* compress_proto */ 144 bsd_decomp_alloc, /* decomp_alloc */ 145 bsd_free, /* decomp_free */ 146 bsd_decomp_init, /* decomp_init */ 147 bsd_reset, /* decomp_reset */ 148 bsd_decompress, /* decompress */ 149 bsd_incomp, /* incomp */ 150 bsd_comp_stats, /* decomp_stat */ 151 }; 152 153 /* 154 * the next two codes should not be changed lightly, as they must not 155 * lie within the contiguous general code space. 156 */ 157 #define CLEAR 256 /* table clear output code */ 158 #define FIRST 257 /* first free entry */ 159 #define LAST 255 160 161 #define MAXCODE(b) ((1 << (b)) - 1) 162 #define BADCODEM1 MAXCODE(BSD_MAX_BITS) 163 164 #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \ 165 ^ (u_int32_t)(prefix)) 166 #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \ 167 + (u_int32_t)(prefix)) 168 169 #define CHECK_GAP 10000 /* Ratio check interval */ 170 171 #define RATIO_SCALE_LOG 8 172 #define RATIO_SCALE (1<<RATIO_SCALE_LOG) 173 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) 174 175 /* 176 * clear the dictionary 177 */ 178 static void 179 bsd_clear(db) 180 struct bsd_db *db; 181 { 182 db->clear_count++; 183 db->max_ent = FIRST-1; 184 db->n_bits = BSD_INIT_BITS; 185 db->ratio = 0; 186 db->bytes_out = 0; 187 db->in_count = 0; 188 db->checkpoint = CHECK_GAP; 189 } 190 191 /* 192 * If the dictionary is full, then see if it is time to reset it. 193 * 194 * Compute the compression ratio using fixed-point arithmetic 195 * with 8 fractional bits. 196 * 197 * Since we have an infinite stream instead of a single file, 198 * watch only the local compression ratio. 199 * 200 * Since both peers must reset the dictionary at the same time even in 201 * the absence of CLEAR codes (while packets are incompressible), they 202 * must compute the same ratio. 203 */ 204 static int /* 1=output CLEAR */ 205 bsd_check(db) 206 struct bsd_db *db; 207 { 208 u_int new_ratio; 209 210 if (db->in_count >= db->checkpoint) { 211 /* age the ratio by limiting the size of the counts */ 212 if (db->in_count >= RATIO_MAX 213 || db->bytes_out >= RATIO_MAX) { 214 db->in_count -= db->in_count/4; 215 db->bytes_out -= db->bytes_out/4; 216 } 217 218 db->checkpoint = db->in_count + CHECK_GAP; 219 220 if (db->max_ent >= db->maxmaxcode) { 221 /* Reset the dictionary only if the ratio is worse, 222 * or if it looks as if it has been poisoned 223 * by incompressible data. 224 * 225 * This does not overflow, because 226 * db->in_count <= RATIO_MAX. 227 */ 228 new_ratio = db->in_count << RATIO_SCALE_LOG; 229 if (db->bytes_out != 0) 230 new_ratio /= db->bytes_out; 231 232 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) { 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 static void 246 bsd_comp_stats(state, stats) 247 void *state; 248 struct compstat *stats; 249 { 250 struct bsd_db *db = (struct bsd_db *) state; 251 u_int out; 252 253 stats->unc_bytes = db->uncomp_bytes; 254 stats->unc_packets = db->uncomp_count; 255 stats->comp_bytes = db->comp_bytes; 256 stats->comp_packets = db->comp_count; 257 stats->inc_bytes = db->incomp_bytes; 258 stats->inc_packets = db->incomp_count; 259 stats->ratio = db->in_count; 260 out = db->bytes_out; 261 if (stats->ratio <= 0x7fffff) 262 stats->ratio <<= 8; 263 else 264 out >>= 8; 265 if (out != 0) 266 stats->ratio /= out; 267 } 268 269 /* 270 * Reset state, as on a CCP ResetReq. 271 */ 272 static void 273 bsd_reset(state) 274 void *state; 275 { 276 struct bsd_db *db = (struct bsd_db *) state; 277 278 db->seqno = 0; 279 bsd_clear(db); 280 db->clear_count = 0; 281 } 282 283 /* 284 * Allocate space for a (de) compressor. 285 */ 286 static void * 287 bsd_alloc(options, opt_len, decomp) 288 u_char *options; 289 int opt_len, decomp; 290 { 291 int bits; 292 u_int newlen, hsize, hshift, maxmaxcode; 293 struct bsd_db *db; 294 295 if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3 296 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) 297 return NULL; 298 299 bits = BSD_NBITS(options[2]); 300 switch (bits) { 301 case 9: /* needs 82152 for both directions */ 302 case 10: /* needs 84144 */ 303 case 11: /* needs 88240 */ 304 case 12: /* needs 96432 */ 305 hsize = 5003; 306 hshift = 4; 307 break; 308 case 13: /* needs 176784 */ 309 hsize = 9001; 310 hshift = 5; 311 break; 312 case 14: /* needs 353744 */ 313 hsize = 18013; 314 hshift = 6; 315 break; 316 case 15: /* needs 691440 */ 317 hsize = 35023; 318 hshift = 7; 319 break; 320 case 16: /* needs 1366160--far too much, */ 321 /* hsize = 69001; */ /* and 69001 is too big for cptr */ 322 /* hshift = 8; */ /* in struct bsd_db */ 323 /* break; */ 324 default: 325 return NULL; 326 } 327 328 maxmaxcode = MAXCODE(bits); 329 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0])); 330 db = (struct bsd_db *) malloc(newlen); 331 if (!db) 332 return NULL; 333 memset(db, 0, sizeof(*db) - sizeof(db->dict)); 334 335 if (!decomp) { 336 db->lens = NULL; 337 } else { 338 db->lens = (u_short *) malloc((maxmaxcode+1) * sizeof(db->lens[0])); 339 if (!db->lens) { 340 free(db); 341 return NULL; 342 } 343 } 344 345 db->totlen = newlen; 346 db->hsize = hsize; 347 db->hshift = hshift; 348 db->maxmaxcode = maxmaxcode; 349 db->maxbits = bits; 350 351 return (void *) db; 352 } 353 354 static void 355 bsd_free(state) 356 void *state; 357 { 358 struct bsd_db *db = (struct bsd_db *) state; 359 360 if (db->lens) 361 free(db->lens); 362 free(db); 363 } 364 365 static void * 366 bsd_decomp_alloc(options, opt_len) 367 u_char *options; 368 int opt_len; 369 { 370 return bsd_alloc(options, opt_len, 1); 371 } 372 373 /* 374 * Initialize the database. 375 */ 376 static int 377 bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp) 378 struct bsd_db *db; 379 u_char *options; 380 int opt_len, unit, hdrlen, mru, debug, decomp; 381 { 382 int i; 383 384 if (opt_len < CILEN_BSD_COMPRESS 385 || options[0] != CI_BSD_COMPRESS || options[1] != CILEN_BSD_COMPRESS 386 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION 387 || BSD_NBITS(options[2]) != db->maxbits 388 || decomp && db->lens == NULL) 389 return 0; 390 391 if (decomp) { 392 i = LAST+1; 393 while (i != 0) 394 db->lens[--i] = 1; 395 } 396 i = db->hsize; 397 while (i != 0) { 398 db->dict[--i].codem1 = BADCODEM1; 399 db->dict[i].cptr = 0; 400 } 401 402 db->unit = unit; 403 db->hdrlen = hdrlen; 404 db->mru = mru; 405 if (debug) 406 db->debug = 1; 407 408 bsd_reset(db); 409 410 return 1; 411 } 412 413 static int 414 bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug) 415 void *state; 416 u_char *options; 417 int opt_len, unit, hdrlen, mru, debug; 418 { 419 return bsd_init((struct bsd_db *) state, options, opt_len, 420 unit, hdrlen, mru, debug, 1); 421 } 422 423 424 /* 425 * Update the "BSD Compress" dictionary on the receiver for 426 * incompressible data by pretending to compress the incoming data. 427 */ 428 static void 429 bsd_incomp(state, dmsg, mlen) 430 void *state; 431 u_char *dmsg; 432 int mlen; 433 { 434 struct bsd_db *db = (struct bsd_db *) state; 435 u_int hshift = db->hshift; 436 u_int max_ent = db->max_ent; 437 u_int n_bits = db->n_bits; 438 struct bsd_dict *dictp; 439 u_int32_t fcode; 440 u_char c; 441 long hval, disp; 442 int slen, ilen; 443 u_int bitno = 7; 444 u_char *rptr; 445 u_int ent; 446 447 rptr = dmsg; 448 ent = rptr[0]; /* get the protocol */ 449 if (ent == 0) { 450 ++rptr; 451 --mlen; 452 ent = rptr[0]; 453 } 454 if ((ent & 1) == 0 || ent < 0x21 || ent > 0xf9) 455 return; 456 457 db->seqno++; 458 ilen = 1; /* count the protocol as 1 byte */ 459 ++rptr; 460 slen = dmsg + mlen - rptr; 461 ilen += slen; 462 for (; slen > 0; --slen) { 463 c = *rptr++; 464 fcode = BSD_KEY(ent, c); 465 hval = BSD_HASH(ent, c, hshift); 466 dictp = &db->dict[hval]; 467 468 /* validate and then check the entry */ 469 if (dictp->codem1 >= max_ent) 470 goto nomatch; 471 if (dictp->f.fcode == fcode) { 472 ent = dictp->codem1+1; 473 continue; /* found (prefix,suffix) */ 474 } 475 476 /* continue probing until a match or invalid entry */ 477 disp = (hval == 0) ? 1 : hval; 478 do { 479 hval += disp; 480 if (hval >= db->hsize) 481 hval -= db->hsize; 482 dictp = &db->dict[hval]; 483 if (dictp->codem1 >= max_ent) 484 goto nomatch; 485 } while (dictp->f.fcode != fcode); 486 ent = dictp->codem1+1; 487 continue; /* finally found (prefix,suffix) */ 488 489 nomatch: /* output (count) the prefix */ 490 bitno += n_bits; 491 492 /* code -> hashtable */ 493 if (max_ent < db->maxmaxcode) { 494 struct bsd_dict *dictp2; 495 /* expand code size if needed */ 496 if (max_ent >= MAXCODE(n_bits)) 497 db->n_bits = ++n_bits; 498 499 /* Invalidate previous hash table entry 500 * assigned this code, and then take it over. 501 */ 502 dictp2 = &db->dict[max_ent+1]; 503 if (db->dict[dictp2->cptr].codem1 == max_ent) 504 db->dict[dictp2->cptr].codem1 = BADCODEM1; 505 dictp2->cptr = hval; 506 dictp->codem1 = max_ent; 507 dictp->f.fcode = fcode; 508 509 db->max_ent = ++max_ent; 510 db->lens[max_ent] = db->lens[ent]+1; 511 } 512 ent = c; 513 } 514 bitno += n_bits; /* output (count) the last code */ 515 db->bytes_out += bitno/8; 516 db->in_count += ilen; 517 (void)bsd_check(db); 518 519 ++db->incomp_count; 520 db->incomp_bytes += ilen; 521 ++db->uncomp_count; 522 db->uncomp_bytes += ilen; 523 524 /* Increase code size if we would have without the packet 525 * boundary and as the decompressor will. 526 */ 527 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) 528 db->n_bits++; 529 } 530 531 532 /* 533 * Decompress "BSD Compress" 534 * 535 * Because of patent problems, we return DECOMP_ERROR for errors 536 * found by inspecting the input data and for system problems, but 537 * DECOMP_FATALERROR for any errors which could possibly be said to 538 * be being detected "after" decompression. For DECOMP_ERROR, 539 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be 540 * infringing a patent of Motorola's if we do, so we take CCP down 541 * instead. 542 * 543 * Given that the frame has the correct sequence number and a good FCS, 544 * errors such as invalid codes in the input most likely indicate a 545 * bug, so we return DECOMP_FATALERROR for them in order to turn off 546 * compression, even though they are detected by inspecting the input. 547 */ 548 static int 549 bsd_decompress(state, cmsg, inlen, dmp, outlenp) 550 void *state; 551 u_char *cmsg, *dmp; 552 int inlen, *outlenp; 553 { 554 struct bsd_db *db = (struct bsd_db *) state; 555 u_int max_ent = db->max_ent; 556 u_int32_t accm = 0; 557 u_int bitno = 32; /* 1st valid bit in accm */ 558 u_int n_bits = db->n_bits; 559 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */ 560 struct bsd_dict *dictp; 561 int explen, i, seq, len; 562 u_int incode, oldcode, finchar; 563 u_char *p, *rptr, *wptr; 564 int ilen; 565 int dlen, space, codelen, extra; 566 567 rptr = cmsg; 568 if (*rptr == 0) 569 ++rptr; 570 ++rptr; /* skip protocol (assumed 0xfd) */ 571 seq = (rptr[0] << 8) + rptr[1]; 572 rptr += BSD_OVHD; 573 ilen = len = cmsg + inlen - rptr; 574 575 /* 576 * Check the sequence number and give up if it is not what we expect. 577 */ 578 if (seq != db->seqno++) { 579 if (db->debug) 580 printf("bsd_decomp%d: bad sequence # %d, expected %d\n", 581 db->unit, seq, db->seqno - 1); 582 return DECOMP_ERROR; 583 } 584 585 wptr = dmp + db->hdrlen; 586 587 oldcode = CLEAR; 588 explen = 0; 589 while (len > 0) { 590 /* 591 * Accumulate bytes until we have a complete code. 592 * Then get the next code, relying on the 32-bit, 593 * unsigned accm to mask the result. 594 */ 595 bitno -= 8; 596 accm |= *rptr++ << bitno; 597 --len; 598 if (tgtbitno < bitno) 599 continue; 600 incode = accm >> tgtbitno; 601 accm <<= n_bits; 602 bitno += n_bits; 603 604 if (incode == CLEAR) { 605 /* 606 * The dictionary must only be cleared at 607 * the end of a packet. But there could be an 608 * empty message block at the end. 609 */ 610 if (len > 0) { 611 if (db->debug) 612 printf("bsd_decomp%d: bad CLEAR\n", db->unit); 613 return DECOMP_FATALERROR; 614 } 615 bsd_clear(db); 616 explen = ilen = 0; 617 break; 618 } 619 620 if (incode > max_ent + 2 || incode > db->maxmaxcode 621 || incode > max_ent && oldcode == CLEAR) { 622 if (db->debug) { 623 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", 624 db->unit, incode, oldcode); 625 printf("max_ent=0x%x dlen=%d seqno=%d\n", 626 max_ent, dlen, db->seqno); 627 } 628 return DECOMP_FATALERROR; /* probably a bug */ 629 } 630 631 /* Special case for KwKwK string. */ 632 if (incode > max_ent) { 633 finchar = oldcode; 634 extra = 1; 635 } else { 636 finchar = incode; 637 extra = 0; 638 } 639 640 codelen = db->lens[finchar]; 641 explen += codelen + extra; 642 if (explen > db->mru + 1) { 643 if (db->debug) 644 printf("bsd_decomp%d: ran out of mru\n", db->unit); 645 return DECOMP_FATALERROR; 646 } 647 648 /* 649 * Decode this code and install it in the decompressed buffer. 650 */ 651 p = (wptr += codelen); 652 while (finchar > LAST) { 653 dictp = &db->dict[db->dict[finchar].cptr]; 654 #ifdef DEBUG 655 --codelen; 656 if (codelen <= 0) { 657 printf("bsd_decomp%d: fell off end of chain ", db->unit); 658 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", 659 incode, finchar, db->dict[finchar].cptr, max_ent); 660 return DECOMP_FATALERROR; 661 } 662 if (dictp->codem1 != finchar-1) { 663 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", 664 db->unit, incode, finchar); 665 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, 666 db->dict[finchar].cptr, dictp->codem1); 667 return DECOMP_FATALERROR; 668 } 669 #endif 670 *--p = dictp->f.hs.suffix; 671 finchar = dictp->f.hs.prefix; 672 } 673 *--p = finchar; 674 675 #ifdef DEBUG 676 if (--codelen != 0) 677 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", 678 db->unit, codelen, incode, max_ent); 679 #endif 680 681 if (extra) /* the KwKwK case again */ 682 *wptr++ = finchar; 683 684 /* 685 * If not first code in a packet, and 686 * if not out of code space, then allocate a new code. 687 * 688 * Keep the hash table correct so it can be used 689 * with uncompressed packets. 690 */ 691 if (oldcode != CLEAR && max_ent < db->maxmaxcode) { 692 struct bsd_dict *dictp2; 693 u_int32_t fcode; 694 int hval, disp; 695 696 fcode = BSD_KEY(oldcode,finchar); 697 hval = BSD_HASH(oldcode,finchar,db->hshift); 698 dictp = &db->dict[hval]; 699 700 /* look for a free hash table entry */ 701 if (dictp->codem1 < max_ent) { 702 disp = (hval == 0) ? 1 : hval; 703 do { 704 hval += disp; 705 if (hval >= db->hsize) 706 hval -= db->hsize; 707 dictp = &db->dict[hval]; 708 } while (dictp->codem1 < max_ent); 709 } 710 711 /* 712 * Invalidate previous hash table entry 713 * assigned this code, and then take it over 714 */ 715 dictp2 = &db->dict[max_ent+1]; 716 if (db->dict[dictp2->cptr].codem1 == max_ent) { 717 db->dict[dictp2->cptr].codem1 = BADCODEM1; 718 } 719 dictp2->cptr = hval; 720 dictp->codem1 = max_ent; 721 dictp->f.fcode = fcode; 722 723 db->max_ent = ++max_ent; 724 db->lens[max_ent] = db->lens[oldcode]+1; 725 726 /* Expand code size if needed. */ 727 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { 728 db->n_bits = ++n_bits; 729 tgtbitno = 32-n_bits; 730 } 731 } 732 oldcode = incode; 733 } 734 *outlenp = wptr - (dmp + db->hdrlen); 735 736 /* 737 * Keep the checkpoint right so that incompressible packets 738 * clear the dictionary at the right times. 739 */ 740 db->bytes_out += ilen; 741 db->in_count += explen; 742 if (bsd_check(db) && db->debug) { 743 printf("bsd_decomp%d: peer should have cleared dictionary\n", 744 db->unit); 745 } 746 747 ++db->comp_count; 748 db->comp_bytes += ilen + BSD_OVHD; 749 ++db->uncomp_count; 750 db->uncomp_bytes += explen; 751 752 return DECOMP_OK; 753 } 754 #endif /* DO_BSD_COMPRESS */ 755