1 /* Because this code is derived from the 4.3BSD compress source:
4 * Copyright (c) 1985, 1986 The Regents of the University of California.
7 * This code is derived from software contributed to Berkeley by
8 * James A. Woods, derived from original work by Spencer Thomas
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
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.
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
41 * This version is for use with mbufs on BSD-derived systems.
43 * $FreeBSD: src/sys/net/bsd_comp.c,v 1.11.2.1 2002/04/14 21:41:48 luigi Exp $
44 * $DragonFly: src/sys/net/bsd_comp.c,v 1.5 2004/04/22 04:21:29 dillon Exp $
47 #include <sys/param.h>
48 #include <sys/systm.h>
49 #include <sys/malloc.h>
51 #include <net/ppp_layer/ppp_defs.h>
53 #define PACKETPTR struct mbuf *
54 #include <net/ppp_layer/ppp_comp.h>
58 * PPP "BSD compress" compression
59 * The differences between this compression and the classic BSD LZW
60 * source are obvious from the requirement that the classic code worked
61 * with files while this handles arbitrarily long streams that
62 * are broken into packets. They are:
64 * When the code size expands, a block of junk is not emitted by
65 * the compressor and not expected by the decompressor.
67 * New codes are not necessarily assigned every time an old
68 * code is output by the compressor. This is because a packet
69 * end forces a code to be emitted, but does not imply that a
70 * new sequence has been seen.
72 * The compression ratio is checked at the first end of a packet
73 * after the appropriate gap. Besides simplifying and speeding
74 * things up, this makes it more likely that the transmitter
75 * and receiver will agree when the dictionary is cleared when
76 * compression is not going well.
80 * A dictionary for doing BSD compress.
83 int totlen; /* length of this structure */
84 u_int hsize; /* size of the hash table */
85 u_char hshift; /* used in hash function */
86 u_char n_bits; /* current bits/code */
90 u_int16_t seqno; /* sequence # of next packet */
91 u_int hdrlen; /* header length to preallocate */
93 u_int maxmaxcode; /* largest valid code */
94 u_int max_ent; /* largest code in use */
95 u_int in_count; /* uncompressed bytes, aged */
96 u_int bytes_out; /* compressed bytes, aged */
97 u_int ratio; /* recent compression ratio */
98 u_int checkpoint; /* when to next check the ratio */
99 u_int clear_count; /* times dictionary cleared */
100 u_int incomp_count; /* incompressible packets */
101 u_int incomp_bytes; /* incompressible bytes */
102 u_int uncomp_count; /* uncompressed packets */
103 u_int uncomp_bytes; /* uncompressed bytes */
104 u_int comp_count; /* compressed packets */
105 u_int comp_bytes; /* compressed bytes */
106 u_int16_t *lens; /* array of lengths of codes */
108 union { /* hash value */
111 #if BYTE_ORDER == LITTLE_ENDIAN
112 u_int16_t prefix; /* preceding code */
113 u_char suffix; /* last character of new code */
117 u_char suffix; /* last character of new code */
118 u_int16_t prefix; /* preceding code */
122 u_int16_t codem1; /* output of hash table -1 */
123 u_int16_t cptr; /* map code to hash table entry */
127 #define BSD_OVHD 2 /* BSD compress overhead/packet */
128 #define BSD_INIT_BITS BSD_MIN_BITS
130 static void bsd_clear (struct bsd_db *db);
131 static int bsd_check (struct bsd_db *db);
132 static void *bsd_alloc (u_char *options, int opt_len, int decomp);
133 static int bsd_init (struct bsd_db *db, u_char *options, int opt_len,
134 int unit, int hdrlen, int mru, int debug,
136 static void *bsd_comp_alloc (u_char *options, int opt_len);
137 static void *bsd_decomp_alloc (u_char *options, int opt_len);
138 static void bsd_free (void *state);
139 static int bsd_comp_init (void *state, u_char *options, int opt_len,
140 int unit, int hdrlen, int debug);
141 static int bsd_decomp_init (void *state, u_char *options, int opt_len,
142 int unit, int hdrlen, int mru, int debug);
143 static int bsd_compress (void *state, struct mbuf **mret,
144 struct mbuf *mp, int slen, int maxolen);
145 static void bsd_incomp (void *state, struct mbuf *dmsg);
146 static int bsd_decompress (void *state, struct mbuf *cmp,
148 static void bsd_reset (void *state);
149 static void bsd_comp_stats (void *state, struct compstat *stats);
152 * Procedures exported to if_ppp.c.
154 struct compressor ppp_bsd_compress = {
155 CI_BSD_COMPRESS, /* compress_proto */
156 bsd_comp_alloc, /* comp_alloc */
157 bsd_free, /* comp_free */
158 bsd_comp_init, /* comp_init */
159 bsd_reset, /* comp_reset */
160 bsd_compress, /* compress */
161 bsd_comp_stats, /* comp_stat */
162 bsd_decomp_alloc, /* decomp_alloc */
163 bsd_free, /* decomp_free */
164 bsd_decomp_init, /* decomp_init */
165 bsd_reset, /* decomp_reset */
166 bsd_decompress, /* decompress */
167 bsd_incomp, /* incomp */
168 bsd_comp_stats, /* decomp_stat */
172 * the next two codes should not be changed lightly, as they must not
173 * lie within the contiguous general code space.
175 #define CLEAR 256 /* table clear output code */
176 #define FIRST 257 /* first free entry */
179 #define MAXCODE(b) ((1 << (b)) - 1)
180 #define BADCODEM1 MAXCODE(BSD_MAX_BITS)
182 #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \
183 ^ (u_int32_t)(prefix))
184 #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \
185 + (u_int32_t)(prefix))
187 #define CHECK_GAP 10000 /* Ratio check interval */
189 #define RATIO_SCALE_LOG 8
190 #define RATIO_SCALE (1<<RATIO_SCALE_LOG)
191 #define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
194 * clear the dictionary
201 db->max_ent = FIRST-1;
202 db->n_bits = BSD_INIT_BITS;
206 db->checkpoint = CHECK_GAP;
210 * If the dictionary is full, then see if it is time to reset it.
212 * Compute the compression ratio using fixed-point arithmetic
213 * with 8 fractional bits.
215 * Since we have an infinite stream instead of a single file,
216 * watch only the local compression ratio.
218 * Since both peers must reset the dictionary at the same time even in
219 * the absence of CLEAR codes (while packets are incompressible), they
220 * must compute the same ratio.
222 static int /* 1=output CLEAR */
228 if (db->in_count >= db->checkpoint) {
229 /* age the ratio by limiting the size of the counts */
230 if (db->in_count >= RATIO_MAX
231 || db->bytes_out >= RATIO_MAX) {
232 db->in_count -= db->in_count/4;
233 db->bytes_out -= db->bytes_out/4;
236 db->checkpoint = db->in_count + CHECK_GAP;
238 if (db->max_ent >= db->maxmaxcode) {
239 /* Reset the dictionary only if the ratio is worse,
240 * or if it looks as if it has been poisoned
241 * by incompressible data.
243 * This does not overflow, because
244 * db->in_count <= RATIO_MAX.
246 new_ratio = db->in_count << RATIO_SCALE_LOG;
247 if (db->bytes_out != 0)
248 new_ratio /= db->bytes_out;
250 if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
254 db->ratio = new_ratio;
264 bsd_comp_stats(state, stats)
266 struct compstat *stats;
268 struct bsd_db *db = (struct bsd_db *) state;
271 stats->unc_bytes = db->uncomp_bytes;
272 stats->unc_packets = db->uncomp_count;
273 stats->comp_bytes = db->comp_bytes;
274 stats->comp_packets = db->comp_count;
275 stats->inc_bytes = db->incomp_bytes;
276 stats->inc_packets = db->incomp_count;
277 stats->ratio = db->in_count;
279 if (stats->ratio <= 0x7fffff)
288 * Reset state, as on a CCP ResetReq.
294 struct bsd_db *db = (struct bsd_db *) state;
302 * Allocate space for a (de) compressor.
305 bsd_alloc(options, opt_len, decomp)
310 u_int newlen, hsize, hshift, maxmaxcode;
313 if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS
314 || options[1] != CILEN_BSD_COMPRESS
315 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
317 bits = BSD_NBITS(options[2]);
319 case 9: /* needs 82152 for both directions */
320 case 10: /* needs 84144 */
321 case 11: /* needs 88240 */
322 case 12: /* needs 96432 */
326 case 13: /* needs 176784 */
330 case 14: /* needs 353744 */
334 case 15: /* needs 691440 */
338 case 16: /* needs 1366160--far too much, */
339 /* hsize = 69001; */ /* and 69001 is too big for cptr */
340 /* hshift = 8; */ /* in struct bsd_db */
346 maxmaxcode = MAXCODE(bits);
347 newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0]));
348 MALLOC(db, struct bsd_db *, newlen, M_DEVBUF, M_WAITOK);
349 bzero(db, sizeof(*db) - sizeof(db->dict));
354 MALLOC(db->lens, u_int16_t *, (maxmaxcode+1) * sizeof(db->lens[0]),
361 db->maxmaxcode = maxmaxcode;
371 struct bsd_db *db = (struct bsd_db *) state;
374 free(db->lens, M_DEVBUF);
379 bsd_comp_alloc(options, opt_len)
383 return bsd_alloc(options, opt_len, 0);
387 bsd_decomp_alloc(options, opt_len)
391 return bsd_alloc(options, opt_len, 1);
395 * Initialize the database.
398 bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp)
401 int opt_len, unit, hdrlen, mru, debug, decomp;
405 if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS
406 || options[1] != CILEN_BSD_COMPRESS
407 || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
408 || BSD_NBITS(options[2]) != db->maxbits
409 || (decomp && db->lens == NULL))
419 db->dict[--i].codem1 = BADCODEM1;
420 db->dict[i].cptr = 0;
437 bsd_comp_init(state, options, opt_len, unit, hdrlen, debug)
440 int opt_len, unit, hdrlen, debug;
442 return bsd_init((struct bsd_db *) state, options, opt_len,
443 unit, hdrlen, 0, debug, 0);
447 bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug)
450 int opt_len, unit, hdrlen, mru, debug;
452 return bsd_init((struct bsd_db *) state, options, opt_len,
453 unit, hdrlen, mru, debug, 1);
459 * One change from the BSD compress command is that when the
460 * code size expands, we do not output a bunch of padding.
463 bsd_compress(state, mret, mp, slen, maxolen)
465 struct mbuf **mret; /* return compressed mbuf chain here */
466 struct mbuf *mp; /* from here */
467 int slen; /* uncompressed length */
468 int maxolen; /* max compressed length */
470 struct bsd_db *db = (struct bsd_db *) state;
471 int hshift = db->hshift;
472 u_int max_ent = db->max_ent;
473 u_int n_bits = db->n_bits;
475 u_int32_t accm = 0, fcode;
476 struct bsd_dict *dictp;
478 int hval, disp, ent, ilen;
484 #define PUTBYTE(v) { \
488 if (wptr >= cp_end) { \
489 m->m_len = wptr - mtod(m, u_char *); \
490 MGET(m->m_next, M_DONTWAIT, MT_DATA); \
494 if (maxolen - olen > MLEN) \
495 MCLGET(m, M_DONTWAIT); \
496 wptr = mtod(m, u_char *); \
497 cp_end = wptr + M_TRAILINGSPACE(m); \
504 #define OUTPUT(ent) { \
506 accm |= ((ent) << bitno); \
508 PUTBYTE(accm >> 24); \
511 } while (bitno <= 24); \
515 * If the protocol is not in the range we're interested in,
516 * just return without compressing the packet. If it is,
517 * the protocol becomes the first byte to compress.
519 rptr = mtod(mp, u_char *);
520 ent = PPP_PROTOCOL(rptr);
521 if (ent < 0x21 || ent > 0xf9) {
526 /* Don't generate compressed packets which are larger than
527 the uncompressed packet. */
531 /* Allocate one mbuf to start with. */
532 MGET(m, M_DONTWAIT, MT_DATA);
536 if (maxolen + db->hdrlen > MLEN)
537 MCLGET(m, M_DONTWAIT);
538 m->m_data += db->hdrlen;
539 wptr = mtod(m, u_char *);
540 cp_end = wptr + M_TRAILINGSPACE(m);
542 wptr = cp_end = NULL;
545 * Copy the PPP header over, changing the protocol,
546 * and install the 2-byte packet sequence number.
549 *wptr++ = PPP_ADDRESS(rptr); /* assumes the ppp header is */
550 *wptr++ = PPP_CONTROL(rptr); /* all in one mbuf */
551 *wptr++ = 0; /* change the protocol */
553 *wptr++ = db->seqno >> 8;
560 slen = mp->m_len - PPP_HDRLEN;
567 rptr = mtod(mp, u_char *);
570 continue; /* handle 0-length buffers */
576 fcode = BSD_KEY(ent, c);
577 hval = BSD_HASH(ent, c, hshift);
578 dictp = &db->dict[hval];
580 /* Validate and then check the entry. */
581 if (dictp->codem1 >= max_ent)
583 if (dictp->f.fcode == fcode) {
584 ent = dictp->codem1+1;
585 continue; /* found (prefix,suffix) */
588 /* continue probing until a match or invalid entry */
589 disp = (hval == 0) ? 1 : hval;
592 if (hval >= db->hsize)
594 dictp = &db->dict[hval];
595 if (dictp->codem1 >= max_ent)
597 } while (dictp->f.fcode != fcode);
598 ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
602 OUTPUT(ent); /* output the prefix */
604 /* code -> hashtable */
605 if (max_ent < db->maxmaxcode) {
606 struct bsd_dict *dictp2;
607 /* expand code size if needed */
608 if (max_ent >= MAXCODE(n_bits))
609 db->n_bits = ++n_bits;
611 /* Invalidate old hash table entry using
612 * this code, and then take it over.
614 dictp2 = &db->dict[max_ent+1];
615 if (db->dict[dictp2->cptr].codem1 == max_ent)
616 db->dict[dictp2->cptr].codem1 = BADCODEM1;
618 dictp->codem1 = max_ent;
619 dictp->f.fcode = fcode;
621 db->max_ent = ++max_ent;
626 OUTPUT(ent); /* output the last code */
627 db->bytes_out += olen;
628 db->in_count += ilen;
630 ++db->bytes_out; /* count complete bytes */
633 OUTPUT(CLEAR); /* do not count the CLEAR */
636 * Pad dribble bits of last code with ones.
637 * Do not emit a completely useless byte of ones.
640 PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
643 m->m_len = wptr - mtod(m, u_char *);
648 * Increase code size if we would have without the packet
649 * boundary and as the decompressor will.
651 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
654 db->uncomp_bytes += ilen;
656 if (olen + PPP_HDRLEN + BSD_OVHD > maxolen) {
657 /* throw away the compressed stuff if it is longer than uncompressed */
663 db->incomp_bytes += ilen;
666 db->comp_bytes += olen + BSD_OVHD;
669 return olen + PPP_HDRLEN + BSD_OVHD;
676 * Update the "BSD Compress" dictionary on the receiver for
677 * incompressible data by pretending to compress the incoming data.
680 bsd_incomp(state, dmsg)
684 struct bsd_db *db = (struct bsd_db *) state;
685 u_int hshift = db->hshift;
686 u_int max_ent = db->max_ent;
687 u_int n_bits = db->n_bits;
688 struct bsd_dict *dictp;
691 u_int32_t hval, disp;
698 * If the protocol is not in the range we're interested in,
699 * just return without looking at the packet. If it is,
700 * the protocol becomes the first byte to "compress".
702 rptr = mtod(dmsg, u_char *);
703 ent = PPP_PROTOCOL(rptr);
704 if (ent < 0x21 || ent > 0xf9)
708 ilen = 1; /* count the protocol as 1 byte */
710 slen = dmsg->m_len - PPP_HDRLEN;
716 rptr = mtod(dmsg, u_char *);
724 fcode = BSD_KEY(ent, c);
725 hval = BSD_HASH(ent, c, hshift);
726 dictp = &db->dict[hval];
728 /* validate and then check the entry */
729 if (dictp->codem1 >= max_ent)
731 if (dictp->f.fcode == fcode) {
732 ent = dictp->codem1+1;
733 continue; /* found (prefix,suffix) */
736 /* continue probing until a match or invalid entry */
737 disp = (hval == 0) ? 1 : hval;
740 if (hval >= db->hsize)
742 dictp = &db->dict[hval];
743 if (dictp->codem1 >= max_ent)
745 } while (dictp->f.fcode != fcode);
746 ent = dictp->codem1+1;
747 continue; /* finally found (prefix,suffix) */
749 nomatch: /* output (count) the prefix */
752 /* code -> hashtable */
753 if (max_ent < db->maxmaxcode) {
754 struct bsd_dict *dictp2;
755 /* expand code size if needed */
756 if (max_ent >= MAXCODE(n_bits))
757 db->n_bits = ++n_bits;
759 /* Invalidate previous hash table entry
760 * assigned this code, and then take it over.
762 dictp2 = &db->dict[max_ent+1];
763 if (db->dict[dictp2->cptr].codem1 == max_ent)
764 db->dict[dictp2->cptr].codem1 = BADCODEM1;
766 dictp->codem1 = max_ent;
767 dictp->f.fcode = fcode;
769 db->max_ent = ++max_ent;
770 db->lens[max_ent] = db->lens[ent]+1;
773 } while (--slen != 0);
775 bitno += n_bits; /* output (count) the last code */
776 db->bytes_out += bitno/8;
777 db->in_count += ilen;
781 db->incomp_bytes += ilen;
783 db->uncomp_bytes += ilen;
785 /* Increase code size if we would have without the packet
786 * boundary and as the decompressor will.
788 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
794 * Decompress "BSD Compress".
796 * Because of patent problems, we return DECOMP_ERROR for errors
797 * found by inspecting the input data and for system problems, but
798 * DECOMP_FATALERROR for any errors which could possibly be said to
799 * be being detected "after" decompression. For DECOMP_ERROR,
800 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
801 * infringing a patent of Motorola's if we do, so we take CCP down
804 * Given that the frame has the correct sequence number and a good FCS,
805 * errors such as invalid codes in the input most likely indicate a
806 * bug, so we return DECOMP_FATALERROR for them in order to turn off
807 * compression, even though they are detected by inspecting the input.
810 bsd_decompress(state, cmp, dmpp)
812 struct mbuf *cmp, **dmpp;
814 struct bsd_db *db = (struct bsd_db *) state;
815 u_int max_ent = db->max_ent;
817 u_int bitno = 32; /* 1st valid bit in accm */
818 u_int n_bits = db->n_bits;
819 u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
820 struct bsd_dict *dictp;
821 int explen, i, seq, len;
822 u_int incode, oldcode, finchar;
823 u_char *p, *rptr, *wptr;
824 struct mbuf *m, *dmp, *mret;
825 int adrs, ctrl, ilen;
826 int space, codelen, extra;
829 * Save the address/control from the PPP header
830 * and then get the sequence number.
833 rptr = mtod(cmp, u_char *);
834 adrs = PPP_ADDRESS(rptr);
835 ctrl = PPP_CONTROL(rptr);
837 len = cmp->m_len - PPP_HDRLEN;
839 for (i = 0; i < 2; ++i) {
844 rptr = mtod(cmp, u_char *);
847 seq = (seq << 8) + *rptr++;
852 * Check the sequence number and give up if it differs from
853 * the value we're expecting.
855 if (seq != db->seqno) {
857 printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
858 db->unit, seq, db->seqno - 1);
864 * Allocate one mbuf to start with.
866 MGETHDR(dmp, M_DONTWAIT, MT_DATA);
872 MCLGET(dmp, M_DONTWAIT);
873 dmp->m_data += db->hdrlen;
874 wptr = mtod(dmp, u_char *);
875 space = M_TRAILINGSPACE(dmp) - PPP_HDRLEN + 1;
878 * Fill in the ppp header, but not the last byte of the protocol
879 * (that comes from the decompressed data).
884 wptr += PPP_HDRLEN - 1;
892 if (!cmp) /* quit at end of message */
894 rptr = mtod(cmp, u_char *);
897 continue; /* handle 0-length buffers */
901 * Accumulate bytes until we have a complete code.
902 * Then get the next code, relying on the 32-bit,
903 * unsigned accm to mask the result.
906 accm |= *rptr++ << bitno;
908 if (tgtbitno < bitno)
910 incode = accm >> tgtbitno;
914 if (incode == CLEAR) {
916 * The dictionary must only be cleared at
917 * the end of a packet. But there could be an
918 * empty mbuf at the end.
920 if (len > 0 || cmp->m_next != NULL) {
921 while ((cmp = cmp->m_next) != NULL)
926 printf("bsd_decomp%d: bad CLEAR\n", db->unit);
927 return DECOMP_FATALERROR; /* probably a bug */
935 if (incode > max_ent + 2 || incode > db->maxmaxcode
936 || (incode > max_ent && oldcode == CLEAR)) {
939 printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
940 db->unit, incode, oldcode);
941 printf("max_ent=0x%x explen=%d seqno=%d\n",
942 max_ent, explen, db->seqno);
944 return DECOMP_FATALERROR; /* probably a bug */
947 /* Special case for KwKwK string. */
948 if (incode > max_ent) {
956 codelen = db->lens[finchar];
957 explen += codelen + extra;
958 if (explen > db->mru + 1) {
961 printf("bsd_decomp%d: ran out of mru\n", db->unit);
963 while ((cmp = cmp->m_next) != NULL)
965 printf(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n",
966 len, finchar, codelen, explen);
969 return DECOMP_FATALERROR;
973 * For simplicity, the decoded characters go in a single mbuf,
974 * so we allocate a single extra cluster mbuf if necessary.
976 if ((space -= codelen + extra) < 0) {
977 dmp->m_len = wptr - mtod(dmp, u_char *);
978 MGET(m, M_DONTWAIT, MT_DATA);
986 MCLGET(m, M_DONTWAIT);
987 space = M_TRAILINGSPACE(m) - (codelen + extra);
989 /* now that's what I call *compression*. */
994 wptr = mtod(dmp, u_char *);
998 * Decode this code and install it in the decompressed buffer.
1000 p = (wptr += codelen);
1001 while (finchar > LAST) {
1002 dictp = &db->dict[db->dict[finchar].cptr];
1004 if (--codelen <= 0 || dictp->codem1 != finchar-1)
1007 *--p = dictp->f.hs.suffix;
1008 finchar = dictp->f.hs.prefix;
1014 printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
1015 db->unit, codelen, incode, max_ent);
1018 if (extra) /* the KwKwK case again */
1022 * If not first code in a packet, and
1023 * if not out of code space, then allocate a new code.
1025 * Keep the hash table correct so it can be used
1026 * with uncompressed packets.
1028 if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
1029 struct bsd_dict *dictp2;
1031 u_int32_t hval, disp;
1033 fcode = BSD_KEY(oldcode,finchar);
1034 hval = BSD_HASH(oldcode,finchar,db->hshift);
1035 dictp = &db->dict[hval];
1037 /* look for a free hash table entry */
1038 if (dictp->codem1 < max_ent) {
1039 disp = (hval == 0) ? 1 : hval;
1042 if (hval >= db->hsize)
1044 dictp = &db->dict[hval];
1045 } while (dictp->codem1 < max_ent);
1049 * Invalidate previous hash table entry
1050 * assigned this code, and then take it over
1052 dictp2 = &db->dict[max_ent+1];
1053 if (db->dict[dictp2->cptr].codem1 == max_ent) {
1054 db->dict[dictp2->cptr].codem1 = BADCODEM1;
1056 dictp2->cptr = hval;
1057 dictp->codem1 = max_ent;
1058 dictp->f.fcode = fcode;
1060 db->max_ent = ++max_ent;
1061 db->lens[max_ent] = db->lens[oldcode]+1;
1063 /* Expand code size if needed. */
1064 if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
1065 db->n_bits = ++n_bits;
1066 tgtbitno = 32-n_bits;
1071 dmp->m_len = wptr - mtod(dmp, u_char *);
1074 * Keep the checkpoint right so that incompressible packets
1075 * clear the dictionary at the right times.
1077 db->bytes_out += ilen;
1078 db->in_count += explen;
1079 if (bsd_check(db) && db->debug) {
1080 printf("bsd_decomp%d: peer should have cleared dictionary\n",
1085 db->comp_bytes += ilen + BSD_OVHD;
1087 db->uncomp_bytes += explen;
1095 printf("bsd_decomp%d: fell off end of chain ", db->unit);
1096 printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
1097 incode, finchar, db->dict[finchar].cptr, max_ent);
1098 } else if (dictp->codem1 != finchar-1) {
1099 printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
1100 db->unit, incode, finchar);
1101 printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
1102 db->dict[finchar].cptr, dictp->codem1);
1105 return DECOMP_FATALERROR;
1108 #endif /* DO_BSD_COMPRESS */