1/* 2 * Copyright (c) 2007 Apple Inc. All rights reserved. 3 * 4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ 5 * 6 * This file contains Original Code and/or Modifications of Original Code 7 * as defined in and that are subject to the Apple Public Source License 8 * Version 2.0 (the 'License'). You may not use this file except in 9 * compliance with the License. The rights granted to you under the License 10 * may not be used to create, or enable the creation or redistribution of, 11 * unlawful or unlicensed copies of an Apple operating system, or to 12 * circumvent, violate, or enable the circumvention or violation of, any 13 * terms of an Apple operating system software license agreement. 14 * 15 * Please obtain a copy of the License at 16 * http://www.opensource.apple.com/apsl/ and read it before using this file. 17 * 18 * The Original Code and all software distributed under the License are 19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 23 * Please see the License for the specific language governing rights and 24 * limitations under the License. 25 * 26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ 27 */ 28/* Because this code is derived from the 4.3BSD compress source: 29 * 30 * 31 * Copyright (c) 1985, 1986 The Regents of the University of California. 32 * All rights reserved. 33 * 34 * This code is derived from software contributed to Berkeley by 35 * James A. Woods, derived from original work by Spencer Thomas 36 * and Joseph Orost. 37 * 38 * Redistribution and use in source and binary forms, with or without 39 * modification, are permitted provided that the following conditions 40 * are met: 41 * 1. Redistributions of source code must retain the above copyright 42 * notice, this list of conditions and the following disclaimer. 43 * 2. Redistributions in binary form must reproduce the above copyright 44 * notice, this list of conditions and the following disclaimer in the 45 * documentation and/or other materials provided with the distribution. 46 * 3. All advertising materials mentioning features or use of this software 47 * must display the following acknowledgement: 48 * This product includes software developed by the University of 49 * California, Berkeley and its contributors. 50 * 4. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 */ 66/* 67 * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce 68 * support for mandatory and extensible security protections. This notice 69 * is included in support of clause 2.2 (b) of the Apple Public License, 70 * Version 2.0. 71 */ 72 73/* 74 * This version is for use with mbufs on BSD-derived systems. 75 * 76 */ 77 78#include <sys/param.h> 79#include <sys/systm.h> 80#include <sys/malloc.h> 81#include <sys/mbuf.h> 82#include <net/ppp_defs.h> 83 84#define PACKETPTR struct mbuf * 85#include <net/ppp_comp.h> 86 87#if CONFIG_MACF_NET 88#include <security/mac_framework.h> 89#endif /* MAC_NET */ 90 91#if DO_BSD_COMPRESS 92/* 93 * PPP "BSD compress" compression 94 * The differences between this compression and the classic BSD LZW 95 * source are obvious from the requirement that the classic code worked 96 * with files while this handles arbitrarily long streams that 97 * are broken into packets. They are: 98 * 99 * When the code size expands, a block of junk is not emitted by 100 * the compressor and not expected by the decompressor. 101 * 102 * New codes are not necessarily assigned every time an old 103 * code is output by the compressor. This is because a packet 104 * end forces a code to be emitted, but does not imply that a 105 * new sequence has been seen. 106 * 107 * The compression ratio is checked at the first end of a packet 108 * after the appropriate gap. Besides simplifying and speeding 109 * things up, this makes it more likely that the transmitter 110 * and receiver will agree when the dictionary is cleared when 111 * compression is not going well. 112 */ 113 114/* 115 * A dictionary for doing BSD compress. 116 */ 117struct bsd_db { 118 int totlen; /* length of this structure */ 119 u_int hsize; /* size of the hash table */ 120 u_char hshift; /* used in hash function */ 121 u_char n_bits; /* current bits/code */ 122 u_char maxbits; 123 u_char debug; 124 u_char unit; 125 u_int16_t seqno; /* sequence # of next packet */ 126 u_int hdrlen; /* header length to preallocate */ 127 u_int mru; 128 u_int maxmaxcode; /* largest valid code */ 129 u_int max_ent; /* largest code in use */ 130 u_int in_count; /* uncompressed bytes, aged */ 131 u_int bytes_out; /* compressed bytes, aged */ 132 u_int ratio; /* recent compression ratio */ 133 u_int checkpoint; /* when to next check the ratio */ 134 u_int clear_count; /* times dictionary cleared */ 135 u_int incomp_count; /* incompressible packets */ 136 u_int incomp_bytes; /* incompressible bytes */ 137 u_int uncomp_count; /* uncompressed packets */ 138 u_int uncomp_bytes; /* uncompressed bytes */ 139 u_int comp_count; /* compressed packets */ 140 u_int comp_bytes; /* compressed bytes */ 141 u_int16_t *lens; /* array of lengths of codes */ 142 struct bsd_dict { 143 union { /* hash value */ 144 u_int32_t fcode; 145 struct { 146#if BYTE_ORDER == LITTLE_ENDIAN 147 u_int16_t prefix; /* preceding code */ 148 u_char suffix; /* last character of new code */ 149 u_char pad; 150#else 151 u_char pad; 152 u_char suffix; /* last character of new code */ 153 u_int16_t prefix; /* preceding code */ 154#endif 155 } hs; 156 } f; 157 u_int16_t codem1; /* output of hash table -1 */ 158 u_int16_t cptr; /* map code to hash table entry */ 159 } dict[1]; 160}; 161 162#define BSD_OVHD 2 /* BSD compress overhead/packet */ 163#define BSD_INIT_BITS BSD_MIN_BITS 164 165static void bsd_clear(struct bsd_db *db); 166static int bsd_check(struct bsd_db *db); 167static void *bsd_alloc(u_char *options, int opt_len, int decomp); 168static int bsd_init_comp_db(struct bsd_db *db, u_char *options, 169 int opt_len, 170 int unit, int hdrlen, int mru, int debug, 171 int decomp); 172static void *bsd_comp_alloc(u_char *options, int opt_len); 173static void *bsd_decomp_alloc(u_char *options, int opt_len); 174static void bsd_free(void *state); 175static int bsd_comp_init(void *state, u_char *options, int opt_len, 176 int unit, int hdrlen, int debug); 177static int bsd_decomp_init(void *state, u_char *options, int opt_len, 178 int unit, int hdrlen, int mru, int debug); 179static int bsd_compress(void *state, struct mbuf **mret, 180 struct mbuf *mp, int slen, int maxolen); 181static void bsd_incomp(void *state, struct mbuf *dmsg); 182static int bsd_decompress(void *state, struct mbuf *cmp, 183 struct mbuf **dmpp); 184static void bsd_reset(void *state); 185static void bsd_comp_stats(void *state, struct compstat *stats); 186 187/* 188 * Procedures exported to if_ppp.c. 189 */ 190struct compressor ppp_bsd_compress = { 191 CI_BSD_COMPRESS, /* compress_proto */ 192 bsd_comp_alloc, /* comp_alloc */ 193 bsd_free, /* comp_free */ 194 bsd_comp_init, /* comp_init */ 195 bsd_reset, /* comp_reset */ 196 bsd_compress, /* compress */ 197 bsd_comp_stats, /* comp_stat */ 198 bsd_decomp_alloc, /* decomp_alloc */ 199 bsd_free, /* decomp_free */ 200 bsd_decomp_init, /* decomp_init */ 201 bsd_reset, /* decomp_reset */ 202 bsd_decompress, /* decompress */ 203 bsd_incomp, /* incomp */ 204 bsd_comp_stats, /* decomp_stat */ 205}; 206 207/* 208 * the next two codes should not be changed lightly, as they must not 209 * lie within the contiguous general code space. 210 */ 211#define CLEAR 256 /* table clear output code */ 212#define FIRST 257 /* first free entry */ 213#define LAST 255 214 215#define MAXCODE(b) ((1 << (b)) - 1) 216#define BADCODEM1 MAXCODE(BSD_MAX_BITS) 217 218#define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \ 219 ^ (u_int32_t)(prefix)) 220#define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \ 221 + (u_int32_t)(prefix)) 222 223#define CHECK_GAP 10000 /* Ratio check interval */ 224 225#define RATIO_SCALE_LOG 8 226#define RATIO_SCALE (1<<RATIO_SCALE_LOG) 227#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG) 228 229/* 230 * clear the dictionary 231 */ 232static void 233bsd_clear(db) 234 struct bsd_db *db; 235{ 236 db->clear_count++; 237 db->max_ent = FIRST-1; 238 db->n_bits = BSD_INIT_BITS; 239 db->ratio = 0; 240 db->bytes_out = 0; 241 db->in_count = 0; 242 db->checkpoint = CHECK_GAP; 243} 244 245/* 246 * If the dictionary is full, then see if it is time to reset it. 247 * 248 * Compute the compression ratio using fixed-point arithmetic 249 * with 8 fractional bits. 250 * 251 * Since we have an infinite stream instead of a single file, 252 * watch only the local compression ratio. 253 * 254 * Since both peers must reset the dictionary at the same time even in 255 * the absence of CLEAR codes (while packets are incompressible), they 256 * must compute the same ratio. 257 */ 258static int /* 1=output CLEAR */ 259bsd_check(db) 260 struct bsd_db *db; 261{ 262 u_int new_ratio; 263 264 if (db->in_count >= db->checkpoint) { 265 /* age the ratio by limiting the size of the counts */ 266 if (db->in_count >= RATIO_MAX 267 || db->bytes_out >= RATIO_MAX) { 268 db->in_count -= db->in_count/4; 269 db->bytes_out -= db->bytes_out/4; 270 } 271 272 db->checkpoint = db->in_count + CHECK_GAP; 273 274 if (db->max_ent >= db->maxmaxcode) { 275 /* Reset the dictionary only if the ratio is worse, 276 * or if it looks as if it has been poisoned 277 * by incompressible data. 278 * 279 * This does not overflow, because 280 * db->in_count <= RATIO_MAX. 281 */ 282 new_ratio = db->in_count << RATIO_SCALE_LOG; 283 if (db->bytes_out != 0) 284 new_ratio /= db->bytes_out; 285 286 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) { 287 bsd_clear(db); 288 return 1; 289 } 290 db->ratio = new_ratio; 291 } 292 } 293 return 0; 294} 295 296/* 297 * Return statistics. 298 */ 299static void 300bsd_comp_stats(state, stats) 301 void *state; 302 struct compstat *stats; 303{ 304 struct bsd_db *db = (struct bsd_db *) state; 305 u_int out; 306 307 stats->unc_bytes = db->uncomp_bytes; 308 stats->unc_packets = db->uncomp_count; 309 stats->comp_bytes = db->comp_bytes; 310 stats->comp_packets = db->comp_count; 311 stats->inc_bytes = db->incomp_bytes; 312 stats->inc_packets = db->incomp_count; 313 stats->ratio = db->in_count; 314 out = db->bytes_out; 315 if (stats->ratio <= 0x7fffff) 316 stats->ratio <<= 8; 317 else 318 out >>= 8; 319 if (out != 0) 320 stats->ratio /= out; 321} 322 323/* 324 * Reset state, as on a CCP ResetReq. 325 */ 326static void 327bsd_reset(state) 328 void *state; 329{ 330 struct bsd_db *db = (struct bsd_db *) state; 331 332 db->seqno = 0; 333 bsd_clear(db); 334 db->clear_count = 0; 335} 336 337/* 338 * Allocate space for a (de) compressor. 339 */ 340static void * 341bsd_alloc(options, opt_len, decomp) 342 u_char *options; 343 int opt_len, decomp; 344{ 345 int bits; 346 u_int newlen, hsize, hshift, maxmaxcode; 347 struct bsd_db *db; 348 349 if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS 350 || options[1] != CILEN_BSD_COMPRESS 351 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) 352 return NULL; 353 bits = BSD_NBITS(options[2]); 354 switch (bits) { 355 case 9: /* needs 82152 for both directions */ 356 case 10: /* needs 84144 */ 357 case 11: /* needs 88240 */ 358 case 12: /* needs 96432 */ 359 hsize = 5003; 360 hshift = 4; 361 break; 362 case 13: /* needs 176784 */ 363 hsize = 9001; 364 hshift = 5; 365 break; 366 case 14: /* needs 353744 */ 367 hsize = 18013; 368 hshift = 6; 369 break; 370 case 15: /* needs 691440 */ 371 hsize = 35023; 372 hshift = 7; 373 break; 374 case 16: /* needs 1366160--far too much, */ 375 /* hsize = 69001; */ /* and 69001 is too big for cptr */ 376 /* hshift = 8; */ /* in struct bsd_db */ 377 /* break; */ 378 default: 379 return NULL; 380 } 381 382 maxmaxcode = MAXCODE(bits); 383 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0])); 384 MALLOC(db, struct bsd_db *, newlen, M_DEVBUF, M_NOWAIT); 385 if (!db) 386 return NULL; 387 bzero(db, sizeof(*db) - sizeof(db->dict)); 388 389 if (!decomp) { 390 db->lens = NULL; 391 } else { 392 MALLOC(db->lens, u_int16_t *, (maxmaxcode+1) * sizeof(db->lens[0]), 393 M_DEVBUF, M_NOWAIT); 394 if (!db->lens) { 395 FREE(db, M_DEVBUF); 396 return NULL; 397 } 398 } 399 400 db->totlen = newlen; 401 db->hsize = hsize; 402 db->hshift = hshift; 403 db->maxmaxcode = maxmaxcode; 404 db->maxbits = bits; 405 406 return (void *) db; 407} 408 409static void 410bsd_free(state) 411 void *state; 412{ 413 struct bsd_db *db = (struct bsd_db *) state; 414 415 if (db->lens) 416 FREE(db->lens, M_DEVBUF); 417 FREE(db, M_DEVBUF); 418} 419 420static void * 421bsd_comp_alloc(options, opt_len) 422 u_char *options; 423 int opt_len; 424{ 425 return bsd_alloc(options, opt_len, 0); 426} 427 428static void * 429bsd_decomp_alloc(options, opt_len) 430 u_char *options; 431 int opt_len; 432{ 433 return bsd_alloc(options, opt_len, 1); 434} 435 436/* 437 * Initialize the database. 438 */ 439static int 440bsd_init_comp_db(db, options, opt_len, unit, hdrlen, mru, debug, decomp) 441 struct bsd_db *db; 442 u_char *options; 443 int opt_len, unit, hdrlen, mru, debug, decomp; 444{ 445 int i; 446 447 if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS 448 || options[1] != CILEN_BSD_COMPRESS 449 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION 450 || BSD_NBITS(options[2]) != db->maxbits 451 || (decomp && db->lens == NULL)) 452 return 0; 453 454 if (decomp) { 455 i = LAST+1; 456 while (i != 0) 457 db->lens[--i] = 1; 458 } 459 i = db->hsize; 460 while (i != 0) { 461 db->dict[--i].codem1 = BADCODEM1; 462 db->dict[i].cptr = 0; 463 } 464 465 db->unit = unit; 466 db->hdrlen = hdrlen; 467 db->mru = mru; 468#if !DEBUG 469 if (debug) 470#endif 471 db->debug = 1; 472 473 bsd_reset(db); 474 475 return 1; 476} 477 478static int 479bsd_comp_init(state, options, opt_len, unit, hdrlen, debug) 480 void *state; 481 u_char *options; 482 int opt_len, unit, hdrlen, debug; 483{ 484 return bsd_init_comp_db((struct bsd_db *) state, options, opt_len, 485 unit, hdrlen, 0, debug, 0); 486} 487 488static int 489bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug) 490 void *state; 491 u_char *options; 492 int opt_len, unit, hdrlen, mru, debug; 493{ 494 return bsd_init_comp_db((struct bsd_db *) state, options, opt_len, 495 unit, hdrlen, mru, debug, 1); 496} 497 498 499/* 500 * compress a packet 501 * One change from the BSD compress command is that when the 502 * code size expands, we do not output a bunch of padding. 503 */ 504int /* new slen */ 505bsd_compress(state, mret, mp, slen, maxolen) 506 void *state; 507 struct mbuf **mret; /* return compressed mbuf chain here */ 508 struct mbuf *mp; /* from here */ 509 int slen; /* uncompressed length */ 510 int maxolen; /* max compressed length */ 511{ 512 struct bsd_db *db = (struct bsd_db *) state; 513 int hshift = db->hshift; 514 u_int max_ent = db->max_ent; 515 u_int n_bits = db->n_bits; 516 u_int bitno = 32; 517 u_int32_t accm = 0, fcode; 518 struct bsd_dict *dictp; 519 u_char c; 520 int hval, disp, ent, ilen; 521 u_char *rptr, *wptr; 522 u_char *cp_end; 523 int olen; 524 struct mbuf *m; 525 526#define PUTBYTE(v) { \ 527 ++olen; \ 528 if (wptr) { \ 529 *wptr++ = (v); \ 530 if (wptr >= cp_end) { \ 531 m->m_len = wptr - mtod(m, u_char *); \ 532 MGET(m->m_next, M_DONTWAIT, MT_DATA); \ 533 m = m->m_next; \ 534 if (m) { \ 535 m->m_len = 0; \ 536 if (maxolen - olen > MLEN) \ 537 MCLGET(m, M_DONTWAIT); \ 538 wptr = mtod(m, u_char *); \ 539 cp_end = wptr + M_TRAILINGSPACE(m); \ 540 } else \ 541 wptr = NULL; \ 542 } \ 543 } \ 544} 545 546#define OUTPUT(ent) { \ 547 bitno -= n_bits; \ 548 accm |= ((ent) << bitno); \ 549 do { \ 550 PUTBYTE(accm >> 24); \ 551 accm <<= 8; \ 552 bitno += 8; \ 553 } while (bitno <= 24); \ 554} 555 556 /* 557 * If the protocol is not in the range we're interested in, 558 * just return without compressing the packet. If it is, 559 * the protocol becomes the first byte to compress. 560 */ 561 rptr = mtod(mp, u_char *); 562 ent = PPP_PROTOCOL(rptr); 563 if (ent < 0x21 || ent > 0xf9) { 564 *mret = NULL; 565 return slen; 566 } 567 568 /* Don't generate compressed packets which are larger than 569 the uncompressed packet. */ 570 if (maxolen > slen) 571 maxolen = slen; 572 573 /* Allocate one mbuf to start with. */ 574 MGET(m, M_DONTWAIT, MT_DATA); 575 *mret = m; 576 if (m != NULL) { 577 m->m_len = 0; 578 if (maxolen + db->hdrlen > MLEN) 579 MCLGET(m, M_DONTWAIT); 580 m->m_data += db->hdrlen; 581 wptr = mtod(m, u_char *); 582 cp_end = wptr + M_TRAILINGSPACE(m); 583 } else 584 wptr = cp_end = NULL; 585 586 /* 587 * Copy the PPP header over, changing the protocol, 588 * and install the 2-byte packet sequence number. 589 */ 590 if (wptr) { 591 *wptr++ = PPP_ADDRESS(rptr); /* assumes the ppp header is */ 592 *wptr++ = PPP_CONTROL(rptr); /* all in one mbuf */ 593 *wptr++ = 0; /* change the protocol */ 594 *wptr++ = PPP_COMP; 595 *wptr++ = db->seqno >> 8; 596 *wptr++ = db->seqno; 597 } 598 ++db->seqno; 599 600 olen = 0; 601 rptr += PPP_HDRLEN; 602 slen = mp->m_len - PPP_HDRLEN; 603 ilen = slen + 1; 604 for (;;) { 605 if (slen <= 0) { 606 mp = mp->m_next; 607 if (!mp) 608 break; 609 rptr = mtod(mp, u_char *); 610 slen = mp->m_len; 611 if (!slen) 612 continue; /* handle 0-length buffers */ 613 ilen += slen; 614 } 615 616 slen--; 617 c = *rptr++; 618 fcode = BSD_KEY(ent, c); 619 hval = BSD_HASH(ent, c, hshift); 620 dictp = &db->dict[hval]; 621 622 /* Validate and then check the entry. */ 623 if (dictp->codem1 >= max_ent) 624 goto nomatch; 625 if (dictp->f.fcode == fcode) { 626 ent = dictp->codem1+1; 627 continue; /* found (prefix,suffix) */ 628 } 629 630 /* continue probing until a match or invalid entry */ 631 disp = (hval == 0) ? 1 : hval; 632 do { 633 hval += disp; 634 if (hval >= db->hsize) 635 hval -= db->hsize; 636 dictp = &db->dict[hval]; 637 if (dictp->codem1 >= max_ent) 638 goto nomatch; 639 } while (dictp->f.fcode != fcode); 640 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */ 641 continue; 642 643 nomatch: 644 OUTPUT(ent); /* output the prefix */ 645 646 /* code -> hashtable */ 647 if (max_ent < db->maxmaxcode) { 648 struct bsd_dict *dictp2; 649 /* expand code size if needed */ 650 if (max_ent >= MAXCODE(n_bits)) 651 db->n_bits = ++n_bits; 652 653 /* Invalidate old hash table entry using 654 * this code, and then take it over. 655 */ 656 dictp2 = &db->dict[max_ent+1]; 657 if (db->dict[dictp2->cptr].codem1 == max_ent) 658 db->dict[dictp2->cptr].codem1 = BADCODEM1; 659 dictp2->cptr = hval; 660 dictp->codem1 = max_ent; 661 dictp->f.fcode = fcode; 662 663 db->max_ent = ++max_ent; 664 } 665 ent = c; 666 } 667 668 OUTPUT(ent); /* output the last code */ 669 db->bytes_out += olen; 670 db->in_count += ilen; 671 if (bitno < 32) 672 ++db->bytes_out; /* count complete bytes */ 673 674 if (bsd_check(db)) 675 OUTPUT(CLEAR); /* do not count the CLEAR */ 676 677 /* 678 * Pad dribble bits of last code with ones. 679 * Do not emit a completely useless byte of ones. 680 */ 681 if (bitno != 32) 682 PUTBYTE((accm | (0xff << (bitno-8))) >> 24); 683 684 if (m != NULL) { 685 m->m_len = wptr - mtod(m, u_char *); 686 m->m_next = NULL; 687 } 688 689 /* 690 * Increase code size if we would have without the packet 691 * boundary and as the decompressor will. 692 */ 693 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) 694 db->n_bits++; 695 696 db->uncomp_bytes += ilen; 697 ++db->uncomp_count; 698 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen) { 699 /* throw away the compressed stuff if it is longer than uncompressed */ 700 if (*mret != NULL) { 701 m_freem(*mret); 702 *mret = NULL; 703 } 704 ++db->incomp_count; 705 db->incomp_bytes += ilen; 706 } else { 707 ++db->comp_count; 708 db->comp_bytes += olen + BSD_OVHD; 709 } 710 711 return olen + PPP_HDRLEN + BSD_OVHD; 712#undef OUTPUT 713#undef PUTBYTE 714} 715 716 717/* 718 * Update the "BSD Compress" dictionary on the receiver for 719 * incompressible data by pretending to compress the incoming data. 720 */ 721static void 722bsd_incomp(state, dmsg) 723 void *state; 724 struct mbuf *dmsg; 725{ 726 struct bsd_db *db = (struct bsd_db *) state; 727 u_int hshift = db->hshift; 728 u_int max_ent = db->max_ent; 729 u_int n_bits = db->n_bits; 730 struct bsd_dict *dictp; 731 u_int32_t fcode; 732 u_char c; 733 u_int32_t hval, disp; 734 int slen, ilen; 735 u_int bitno = 7; 736 u_char *rptr; 737 u_int ent; 738 739 /* 740 * If the protocol is not in the range we're interested in, 741 * just return without looking at the packet. If it is, 742 * the protocol becomes the first byte to "compress". 743 */ 744 rptr = mtod(dmsg, u_char *); 745 ent = PPP_PROTOCOL(rptr); 746 if (ent < 0x21 || ent > 0xf9) 747 return; 748 749 db->seqno++; 750 ilen = 1; /* count the protocol as 1 byte */ 751 rptr += PPP_HDRLEN; 752 slen = dmsg->m_len - PPP_HDRLEN; 753 for (;;) { 754 if (slen <= 0) { 755 dmsg = dmsg->m_next; 756 if (!dmsg) 757 break; 758 rptr = mtod(dmsg, u_char *); 759 slen = dmsg->m_len; 760 continue; 761 } 762 ilen += slen; 763 764 do { 765 c = *rptr++; 766 fcode = BSD_KEY(ent, c); 767 hval = BSD_HASH(ent, c, hshift); 768 dictp = &db->dict[hval]; 769 770 /* validate and then check the entry */ 771 if (dictp->codem1 >= max_ent) 772 goto nomatch; 773 if (dictp->f.fcode == fcode) { 774 ent = dictp->codem1+1; 775 continue; /* found (prefix,suffix) */ 776 } 777 778 /* continue probing until a match or invalid entry */ 779 disp = (hval == 0) ? 1 : hval; 780 do { 781 hval += disp; 782 if (hval >= db->hsize) 783 hval -= db->hsize; 784 dictp = &db->dict[hval]; 785 if (dictp->codem1 >= max_ent) 786 goto nomatch; 787 } while (dictp->f.fcode != fcode); 788 ent = dictp->codem1+1; 789 continue; /* finally found (prefix,suffix) */ 790 791 nomatch: /* output (count) the prefix */ 792 bitno += n_bits; 793 794 /* code -> hashtable */ 795 if (max_ent < db->maxmaxcode) { 796 struct bsd_dict *dictp2; 797 /* expand code size if needed */ 798 if (max_ent >= MAXCODE(n_bits)) 799 db->n_bits = ++n_bits; 800 801 /* Invalidate previous hash table entry 802 * assigned this code, and then take it over. 803 */ 804 dictp2 = &db->dict[max_ent+1]; 805 if (db->dict[dictp2->cptr].codem1 == max_ent) 806 db->dict[dictp2->cptr].codem1 = BADCODEM1; 807 dictp2->cptr = hval; 808 dictp->codem1 = max_ent; 809 dictp->f.fcode = fcode; 810 811 db->max_ent = ++max_ent; 812 db->lens[max_ent] = db->lens[ent]+1; 813 } 814 ent = c; 815 } while (--slen != 0); 816 } 817 bitno += n_bits; /* output (count) the last code */ 818 db->bytes_out += bitno/8; 819 db->in_count += ilen; 820 (void)bsd_check(db); 821 822 ++db->incomp_count; 823 db->incomp_bytes += ilen; 824 ++db->uncomp_count; 825 db->uncomp_bytes += ilen; 826 827 /* Increase code size if we would have without the packet 828 * boundary and as the decompressor will. 829 */ 830 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) 831 db->n_bits++; 832} 833 834 835/* 836 * Decompress "BSD Compress". 837 * 838 * Because of patent problems, we return DECOMP_ERROR for errors 839 * found by inspecting the input data and for system problems, but 840 * DECOMP_FATALERROR for any errors which could possibly be said to 841 * be being detected "after" decompression. For DECOMP_ERROR, 842 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be 843 * infringing a patent of Motorola's if we do, so we take CCP down 844 * instead. 845 * 846 * Given that the frame has the correct sequence number and a good FCS, 847 * errors such as invalid codes in the input most likely indicate a 848 * bug, so we return DECOMP_FATALERROR for them in order to turn off 849 * compression, even though they are detected by inspecting the input. 850 */ 851int 852bsd_decompress(state, cmp, dmpp) 853 void *state; 854 struct mbuf *cmp, **dmpp; 855{ 856 struct bsd_db *db = (struct bsd_db *) state; 857 u_int max_ent = db->max_ent; 858 u_int32_t accm = 0; 859 u_int bitno = 32; /* 1st valid bit in accm */ 860 u_int n_bits = db->n_bits; 861 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */ 862 struct bsd_dict *dictp; 863 int explen, i, seq, len; 864 u_int incode, oldcode, finchar; 865 u_char *p, *rptr, *wptr; 866 struct mbuf *m, *dmp, *mret; 867 int adrs, ctrl, ilen; 868 int space, codelen, extra; 869 870 /* 871 * Save the address/control from the PPP header 872 * and then get the sequence number. 873 */ 874 *dmpp = NULL; 875 rptr = mtod(cmp, u_char *); 876 adrs = PPP_ADDRESS(rptr); 877 ctrl = PPP_CONTROL(rptr); 878 rptr += PPP_HDRLEN; 879 len = cmp->m_len - PPP_HDRLEN; 880 seq = 0; 881 for (i = 0; i < 2; ++i) { 882 while (len <= 0) { 883 cmp = cmp->m_next; 884 if (cmp == NULL) 885 return DECOMP_ERROR; 886 rptr = mtod(cmp, u_char *); 887 len = cmp->m_len; 888 } 889 seq = (seq << 8) + *rptr++; 890 --len; 891 } 892 893 /* 894 * Check the sequence number and give up if it differs from 895 * the value we're expecting. 896 */ 897 if (seq != db->seqno) { 898 if (db->debug) 899 printf("bsd_decomp%d: bad sequence # %d, expected %d\n", 900 db->unit, seq, db->seqno - 1); 901 return DECOMP_ERROR; 902 } 903 ++db->seqno; 904 905 /* 906 * Allocate one mbuf to start with. 907 */ 908 MGETHDR(dmp, M_DONTWAIT, MT_DATA); 909 if (dmp == NULL) 910 return DECOMP_ERROR; 911 mret = dmp; 912 dmp->m_len = 0; 913 dmp->m_next = NULL; 914 MCLGET(dmp, M_DONTWAIT); 915 dmp->m_data += db->hdrlen; 916 wptr = mtod(dmp, u_char *); 917 space = M_TRAILINGSPACE(dmp) - PPP_HDRLEN + 1; 918#if CONFIG_MACF_NET 919 mac_mbuf_label_copy(cmp, dmp); 920#endif 921 922 /* 923 * Fill in the ppp header, but not the last byte of the protocol 924 * (that comes from the decompressed data). 925 */ 926 wptr[0] = adrs; 927 wptr[1] = ctrl; 928 wptr[2] = 0; 929 wptr += PPP_HDRLEN - 1; 930 931 ilen = len; 932 oldcode = CLEAR; 933 explen = 0; 934 for (;;) { 935 if (len == 0) { 936 cmp = cmp->m_next; 937 if (!cmp) /* quit at end of message */ 938 break; 939 rptr = mtod(cmp, u_char *); 940 len = cmp->m_len; 941 ilen += len; 942 continue; /* handle 0-length buffers */ 943 } 944 945 /* 946 * Accumulate bytes until we have a complete code. 947 * Then get the next code, relying on the 32-bit, 948 * unsigned accm to mask the result. 949 */ 950 bitno -= 8; 951 accm |= *rptr++ << bitno; 952 --len; 953 if (tgtbitno < bitno) 954 continue; 955 incode = accm >> tgtbitno; 956 accm <<= n_bits; 957 bitno += n_bits; 958 959 if (incode == CLEAR) { 960 /* 961 * The dictionary must only be cleared at 962 * the end of a packet. But there could be an 963 * empty mbuf at the end. 964 */ 965 if (len > 0 || cmp->m_next != NULL) { 966 while ((cmp = cmp->m_next) != NULL) 967 len += cmp->m_len; 968 if (len > 0) { 969 m_freem(mret); 970 if (db->debug) 971 printf("bsd_decomp%d: bad CLEAR\n", db->unit); 972 return DECOMP_FATALERROR; /* probably a bug */ 973 } 974 } 975 bsd_clear(db); 976 explen = ilen = 0; 977 break; 978 } 979 980 if (incode > max_ent + 2 || incode > db->maxmaxcode 981 || (incode > max_ent && oldcode == CLEAR)) { 982 m_freem(mret); 983 if (db->debug) { 984 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", 985 db->unit, incode, oldcode); 986 printf("max_ent=0x%x explen=%d seqno=%d\n", 987 max_ent, explen, db->seqno); 988 } 989 return DECOMP_FATALERROR; /* probably a bug */ 990 } 991 992 /* Special case for KwKwK string. */ 993 if (incode > max_ent) { 994 finchar = oldcode; 995 extra = 1; 996 } else { 997 finchar = incode; 998 extra = 0; 999 } 1000 1001 codelen = db->lens[finchar]; 1002 explen += codelen + extra; 1003 if (explen > db->mru + 1) { 1004 m_freem(mret); 1005 if (db->debug) { 1006 printf("bsd_decomp%d: ran out of mru\n", db->unit); 1007#if DEBUG 1008 while ((cmp = cmp->m_next) != NULL) 1009 len += cmp->m_len; 1010 printf(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n", 1011 len, finchar, codelen, explen); 1012#endif 1013 } 1014 return DECOMP_FATALERROR; 1015 } 1016 1017 /* 1018 * For simplicity, the decoded characters go in a single mbuf, 1019 * so we allocate a single extra cluster mbuf if necessary. 1020 */ 1021 if ((space -= codelen + extra) < 0) { 1022 dmp->m_len = wptr - mtod(dmp, u_char *); 1023 MGET(m, M_DONTWAIT, MT_DATA); 1024 if (m == NULL) { 1025 m_freem(mret); 1026 return DECOMP_ERROR; 1027 } 1028 m->m_len = 0; 1029 m->m_next = NULL; 1030 dmp->m_next = m; 1031 MCLGET(m, M_DONTWAIT); 1032 space = M_TRAILINGSPACE(m) - (codelen + extra); 1033 if (space < 0) { 1034 /* now that's what I call *compression*. */ 1035 m_freem(mret); 1036 return DECOMP_ERROR; 1037 } 1038 dmp = m; 1039 wptr = mtod(dmp, u_char *); 1040 } 1041 1042 /* 1043 * Decode this code and install it in the decompressed buffer. 1044 */ 1045 p = (wptr += codelen); 1046 while (finchar > LAST) { 1047 dictp = &db->dict[db->dict[finchar].cptr]; 1048#if DEBUG 1049 if (--codelen <= 0 || dictp->codem1 != finchar-1) 1050 goto bad; 1051#endif 1052 *--p = dictp->f.hs.suffix; 1053 finchar = dictp->f.hs.prefix; 1054 } 1055 *--p = finchar; 1056 1057#if DEBUG 1058 if (--codelen != 0) 1059 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", 1060 db->unit, codelen, incode, max_ent); 1061#endif 1062 1063 if (extra) /* the KwKwK case again */ 1064 *wptr++ = finchar; 1065 1066 /* 1067 * If not first code in a packet, and 1068 * if not out of code space, then allocate a new code. 1069 * 1070 * Keep the hash table correct so it can be used 1071 * with uncompressed packets. 1072 */ 1073 if (oldcode != CLEAR && max_ent < db->maxmaxcode) { 1074 struct bsd_dict *dictp2; 1075 u_int32_t fcode; 1076 u_int32_t hval, disp; 1077 1078 fcode = BSD_KEY(oldcode,finchar); 1079 hval = BSD_HASH(oldcode,finchar,db->hshift); 1080 dictp = &db->dict[hval]; 1081 1082 /* look for a free hash table entry */ 1083 if (dictp->codem1 < max_ent) { 1084 disp = (hval == 0) ? 1 : hval; 1085 do { 1086 hval += disp; 1087 if (hval >= db->hsize) 1088 hval -= db->hsize; 1089 dictp = &db->dict[hval]; 1090 } while (dictp->codem1 < max_ent); 1091 } 1092 1093 /* 1094 * Invalidate previous hash table entry 1095 * assigned this code, and then take it over 1096 */ 1097 dictp2 = &db->dict[max_ent+1]; 1098 if (db->dict[dictp2->cptr].codem1 == max_ent) { 1099 db->dict[dictp2->cptr].codem1 = BADCODEM1; 1100 } 1101 dictp2->cptr = hval; 1102 dictp->codem1 = max_ent; 1103 dictp->f.fcode = fcode; 1104 1105 db->max_ent = ++max_ent; 1106 db->lens[max_ent] = db->lens[oldcode]+1; 1107 1108 /* Expand code size if needed. */ 1109 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) { 1110 db->n_bits = ++n_bits; 1111 tgtbitno = 32-n_bits; 1112 } 1113 } 1114 oldcode = incode; 1115 } 1116 dmp->m_len = wptr - mtod(dmp, u_char *); 1117 1118 /* 1119 * Keep the checkpoint right so that incompressible packets 1120 * clear the dictionary at the right times. 1121 */ 1122 db->bytes_out += ilen; 1123 db->in_count += explen; 1124 if (bsd_check(db) && db->debug) { 1125 printf("bsd_decomp%d: peer should have cleared dictionary\n", 1126 db->unit); 1127 } 1128 1129 ++db->comp_count; 1130 db->comp_bytes += ilen + BSD_OVHD; 1131 ++db->uncomp_count; 1132 db->uncomp_bytes += explen; 1133 1134 *dmpp = mret; 1135 return DECOMP_OK; 1136 1137#if DEBUG 1138 bad: 1139 if (codelen <= 0) { 1140 printf("bsd_decomp%d: fell off end of chain ", db->unit); 1141 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", 1142 incode, finchar, db->dict[finchar].cptr, max_ent); 1143 } else if (dictp->codem1 != finchar-1) { 1144 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", 1145 db->unit, incode, finchar); 1146 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, 1147 db->dict[finchar].cptr, dictp->codem1); 1148 } 1149 m_freem(mret); 1150 return DECOMP_FATALERROR; 1151#endif /* DEBUG */ 1152} 1153#endif /* DO_BSD_COMPRESS */ 1154