-/* Because this code is derived from the 4.3BSD compress source:
- *
- *
- * Copyright (c) 1985, 1986 The Regents of the University of California.
- * All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * James A. Woods, derived from original work by Spencer Thomas
- * and Joseph Orost.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * This product includes software developed by the University of
- * California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-/*
- * This version is for use with mbufs on BSD-derived systems.
- *
- * $Id: bsd-comp.c,v 1.2 1996/01/18 03:12:35 paulus Exp $
- */
-
-#include <sys/param.h>
-#include <sys/systm.h>
-#include <sys/types.h>
-#include <sys/mbuf.h>
-#include <sys/socket.h>
-#include <net/if.h>
-#include <net/if_types.h>
-#include <net/ppp_defs.h>
-#include <net/if_ppp.h>
-
-#define PACKETPTR struct mbuf *
-#include <net/ppp-comp.h>
-
-#if DO_BSD_COMPRESS
-/*
- * PPP "BSD compress" compression
- * The differences between this compression and the classic BSD LZW
- * source are obvious from the requirement that the classic code worked
- * with files while this handles arbitrarily long streams that
- * are broken into packets. They are:
- *
- * When the code size expands, a block of junk is not emitted by
- * the compressor and not expected by the decompressor.
- *
- * New codes are not necessarily assigned every time an old
- * code is output by the compressor. This is because a packet
- * end forces a code to be emitted, but does not imply that a
- * new sequence has been seen.
- *
- * The compression ratio is checked at the first end of a packet
- * after the appropriate gap. Besides simplifying and speeding
- * things up, this makes it more likely that the transmitter
- * and receiver will agree when the dictionary is cleared when
- * compression is not going well.
- */
-
-/*
- * A dictionary for doing BSD compress.
- */
-struct bsd_db {
- int totlen; /* length of this structure */
- u_int hsize; /* size of the hash table */
- u_char hshift; /* used in hash function */
- u_char n_bits; /* current bits/code */
- u_char maxbits;
- u_char debug;
- u_char unit;
- u_int16_t seqno; /* sequence # of next packet */
- u_int hdrlen; /* header length to preallocate */
- u_int mru;
- u_int maxmaxcode; /* largest valid code */
- u_int max_ent; /* largest code in use */
- u_int in_count; /* uncompressed bytes, aged */
- u_int bytes_out; /* compressed bytes, aged */
- u_int ratio; /* recent compression ratio */
- u_int checkpoint; /* when to next check the ratio */
- u_int clear_count; /* times dictionary cleared */
- u_int incomp_count; /* incompressible packets */
- u_int incomp_bytes; /* incompressible bytes */
- u_int uncomp_count; /* uncompressed packets */
- u_int uncomp_bytes; /* uncompressed bytes */
- u_int comp_count; /* compressed packets */
- u_int comp_bytes; /* compressed bytes */
- u_int16_t *lens; /* array of lengths of codes */
- struct bsd_dict {
- union { /* hash value */
- u_int32_t fcode;
- struct {
-#if BYTE_ORDER == LITTLE_ENDIAN
- u_int16_t prefix; /* preceding code */
- u_char suffix; /* last character of new code */
- u_char pad;
-#else
- u_char pad;
- u_char suffix; /* last character of new code */
- u_int16_t prefix; /* preceding code */
-#endif
- } hs;
- } f;
- u_int16_t codem1; /* output of hash table -1 */
- u_int16_t cptr; /* map code to hash table entry */
- } dict[1];
-};
-
-#define BSD_OVHD 2 /* BSD compress overhead/packet */
-#define BSD_INIT_BITS BSD_MIN_BITS
-
-static void *bsd_comp_alloc __P((u_char *options, int opt_len));
-static void *bsd_decomp_alloc __P((u_char *options, int opt_len));
-static void bsd_free __P((void *state));
-static int bsd_comp_init __P((void *state, u_char *options, int opt_len,
- int unit, int hdrlen, int debug));
-static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
- int unit, int hdrlen, int mru, int debug));
-static int bsd_compress __P((void *state, struct mbuf **mret,
- struct mbuf *mp, int slen, int maxolen));
-static void bsd_incomp __P((void *state, struct mbuf *dmsg));
-static int bsd_decompress __P((void *state, struct mbuf *cmp,
- struct mbuf **dmpp));
-static void bsd_reset __P((void *state));
-static void bsd_comp_stats __P((void *state, struct compstat *stats));
-
-/*
- * Procedures exported to if_ppp.c.
- */
-struct compressor ppp_bsd_compress = {
- CI_BSD_COMPRESS, /* compress_proto */
- bsd_comp_alloc, /* comp_alloc */
- bsd_free, /* comp_free */
- bsd_comp_init, /* comp_init */
- bsd_reset, /* comp_reset */
- bsd_compress, /* compress */
- bsd_comp_stats, /* comp_stat */
- bsd_decomp_alloc, /* decomp_alloc */
- bsd_free, /* decomp_free */
- bsd_decomp_init, /* decomp_init */
- bsd_reset, /* decomp_reset */
- bsd_decompress, /* decompress */
- bsd_incomp, /* incomp */
- bsd_comp_stats, /* decomp_stat */
-};
-
-/*
- * the next two codes should not be changed lightly, as they must not
- * lie within the contiguous general code space.
- */
-#define CLEAR 256 /* table clear output code */
-#define FIRST 257 /* first free entry */
-#define LAST 255
-
-#define MAXCODE(b) ((1 << (b)) - 1)
-#define BADCODEM1 MAXCODE(BSD_MAX_BITS)
-
-#define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \
- ^ (u_int32_t)(prefix))
-#define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \
- + (u_int32_t)(prefix))
-
-#define CHECK_GAP 10000 /* Ratio check interval */
-
-#define RATIO_SCALE_LOG 8
-#define RATIO_SCALE (1<<RATIO_SCALE_LOG)
-#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
-
-/*
- * clear the dictionary
- */
-static void
-bsd_clear(db)
- struct bsd_db *db;
-{
- db->clear_count++;
- db->max_ent = FIRST-1;
- db->n_bits = BSD_INIT_BITS;
- db->ratio = 0;
- db->bytes_out = 0;
- db->in_count = 0;
- db->incomp_count = 0;
- db->checkpoint = CHECK_GAP;
-}
-
-/*
- * If the dictionary is full, then see if it is time to reset it.
- *
- * Compute the compression ratio using fixed-point arithmetic
- * with 8 fractional bits.
- *
- * Since we have an infinite stream instead of a single file,
- * watch only the local compression ratio.
- *
- * Since both peers must reset the dictionary at the same time even in
- * the absence of CLEAR codes (while packets are incompressible), they
- * must compute the same ratio.
- */
-static int /* 1=output CLEAR */
-bsd_check(db)
- struct bsd_db *db;
-{
- u_int new_ratio;
-
- if (db->in_count >= db->checkpoint) {
- /* age the ratio by limiting the size of the counts */
- if (db->in_count >= RATIO_MAX
- || db->bytes_out >= RATIO_MAX) {
- db->in_count -= db->in_count/4;
- db->bytes_out -= db->bytes_out/4;
- }
-
- db->checkpoint = db->in_count + CHECK_GAP;
-
- if (db->max_ent >= db->maxmaxcode) {
- /* Reset the dictionary only if the ratio is worse,
- * or if it looks as if it has been poisoned
- * by incompressible data.
- *
- * This does not overflow, because
- * db->in_count <= RATIO_MAX.
- */
- new_ratio = db->in_count << RATIO_SCALE_LOG;
- if (db->bytes_out != 0)
- new_ratio /= db->bytes_out;
-
- if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
- bsd_clear(db);
- return 1;
- }
- db->ratio = new_ratio;
- }
- }
- return 0;
-}
-
-/*
- * Return statistics.
- */
-static void
-bsd_comp_stats(state, stats)
- void *state;
- struct compstat *stats;
-{
- struct bsd_db *db = (struct bsd_db *) state;
- u_int out;
-
- stats->unc_bytes = db->uncomp_bytes;
- stats->unc_packets = db->uncomp_count;
- stats->comp_bytes = db->comp_bytes;
- stats->comp_packets = db->comp_count;
- stats->inc_bytes = db->incomp_bytes;
- stats->inc_packets = db->incomp_count;
- stats->ratio = db->in_count;
- out = db->bytes_out;
- if (stats->ratio <= 0x7fffff)
- stats->ratio <<= 8;
- else
- out >>= 8;
- if (out != 0)
- stats->ratio /= out;
-}
-
-/*
- * Reset state, as on a CCP ResetReq.
- */
-static void
-bsd_reset(state)
- void *state;
-{
- struct bsd_db *db = (struct bsd_db *) state;
-
- db->seqno = 0;
- bsd_clear(db);
- db->clear_count = 0;
-}
-
-/*
- * Allocate space for a (de) compressor.
- */
-static void *
-bsd_alloc(options, opt_len, decomp)
- u_char *options;
- int opt_len, decomp;
-{
- int bits;
- u_int newlen, hsize, hshift, maxmaxcode;
- struct bsd_db *db;
-
- if (opt_len != CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS
- || options[1] != CILEN_BSD_COMPRESS
- || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
- return NULL;
- bits = BSD_NBITS(options[2]);
- switch (bits) {
- case 9: /* needs 82152 for both directions */
- case 10: /* needs 84144 */
- case 11: /* needs 88240 */
- case 12: /* needs 96432 */
- hsize = 5003;
- hshift = 4;
- break;
- case 13: /* needs 176784 */
- hsize = 9001;
- hshift = 5;
- break;
- case 14: /* needs 353744 */
- hsize = 18013;
- hshift = 6;
- break;
- case 15: /* needs 691440 */
- hsize = 35023;
- hshift = 7;
- break;
- case 16: /* needs 1366160--far too much, */
- /* hsize = 69001; */ /* and 69001 is too big for cptr */
- /* hshift = 8; */ /* in struct bsd_db */
- /* break; */
- default:
- return NULL;
- }
-
- maxmaxcode = MAXCODE(bits);
- newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0]));
- MALLOC(db, struct bsd_db *, newlen, M_DEVBUF, M_NOWAIT);
- if (!db)
- return NULL;
- bzero(db, sizeof(*db) - sizeof(db->dict));
-
- if (!decomp) {
- db->lens = NULL;
- } else {
- MALLOC(db->lens, u_int16_t *, (maxmaxcode+1) * sizeof(db->lens[0]),
- M_DEVBUF, M_NOWAIT);
- if (!db->lens) {
- FREE(db, M_DEVBUF);
- return NULL;
- }
- }
-
- db->totlen = newlen;
- db->hsize = hsize;
- db->hshift = hshift;
- db->maxmaxcode = maxmaxcode;
- db->maxbits = bits;
-
- return (void *) db;
-}
-
-static void
-bsd_free(state)
- void *state;
-{
- struct bsd_db *db = (struct bsd_db *) state;
-
- if (db->lens)
- FREE(db->lens, M_DEVBUF);
- FREE(db, M_DEVBUF);
-}
-
-static void *
-bsd_comp_alloc(options, opt_len)
- u_char *options;
- int opt_len;
-{
- return bsd_alloc(options, opt_len, 0);
-}
-
-static void *
-bsd_decomp_alloc(options, opt_len)
- u_char *options;
- int opt_len;
-{
- return bsd_alloc(options, opt_len, 1);
-}
-
-/*
- * Initialize the database.
- */
-static int
-bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp)
- struct bsd_db *db;
- u_char *options;
- int opt_len, unit, hdrlen, mru, debug, decomp;
-{
- int i;
-
- if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS
- || options[1] != CILEN_BSD_COMPRESS
- || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
- || BSD_NBITS(options[2]) != db->maxbits
- || decomp && db->lens == NULL)
- return 0;
-
- if (decomp) {
- i = LAST+1;
- while (i != 0)
- db->lens[--i] = 1;
- }
- i = db->hsize;
- while (i != 0) {
- db->dict[--i].codem1 = BADCODEM1;
- db->dict[i].cptr = 0;
- }
-
- db->unit = unit;
- db->hdrlen = hdrlen;
- db->mru = mru;
-#ifndef DEBUG
- if (debug)
-#endif
- db->debug = 1;
-
- bsd_reset(db);
-
- return 1;
-}
-
-static int
-bsd_comp_init(state, options, opt_len, unit, hdrlen, debug)
- void *state;
- u_char *options;
- int opt_len, unit, hdrlen, debug;
-{
- return bsd_init((struct bsd_db *) state, options, opt_len,
- unit, hdrlen, 0, debug, 0);
-}
-
-static int
-bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug)
- void *state;
- u_char *options;
- int opt_len, unit, hdrlen, mru, debug;
-{
- return bsd_init((struct bsd_db *) state, options, opt_len,
- unit, hdrlen, mru, debug, 1);
-}
-
-
-/*
- * compress a packet
- * One change from the BSD compress command is that when the
- * code size expands, we do not output a bunch of padding.
- */
-int /* new slen */
-bsd_compress(state, mret, mp, slen, maxolen)
- void *state;
- struct mbuf **mret; /* return compressed mbuf chain here */
- struct mbuf *mp; /* from here */
- int slen; /* uncompressed length */
- int maxolen; /* max compressed length */
-{
- struct bsd_db *db = (struct bsd_db *) state;
- int hshift = db->hshift;
- u_int max_ent = db->max_ent;
- u_int n_bits = db->n_bits;
- u_int bitno = 32;
- u_int32_t accm = 0, fcode;
- struct bsd_dict *dictp;
- u_char c;
- int hval, disp, ent, ilen;
- struct mbuf *np;
- u_char *rptr, *wptr;
- u_char *cp_end;
- int olen;
- struct mbuf *m, **mnp;
-
-#define PUTBYTE(v) { \
- ++olen; \
- if (wptr) { \
- *wptr++ = (v); \
- if (wptr >= cp_end) { \
- m->m_len = wptr - mtod(m, u_char *); \
- MGET(m->m_next, M_DONTWAIT, MT_DATA); \
- m = m->m_next; \
- if (m) { \
- m->m_len = 0; \
- if (maxolen - olen > MLEN) \
- MCLGET(m, M_DONTWAIT); \
- wptr = mtod(m, u_char *); \
- cp_end = wptr + M_TRAILINGSPACE(m); \
- } else \
- wptr = NULL; \
- } \
- } \
-}
-
-#define OUTPUT(ent) { \
- bitno -= n_bits; \
- accm |= ((ent) << bitno); \
- do { \
- PUTBYTE(accm >> 24); \
- accm <<= 8; \
- bitno += 8; \
- } while (bitno <= 24); \
-}
-
- /*
- * If the protocol is not in the range we're interested in,
- * just return without compressing the packet. If it is,
- * the protocol becomes the first byte to compress.
- */
- rptr = mtod(mp, u_char *);
- ent = PPP_PROTOCOL(rptr);
- if (ent < 0x21 || ent > 0xf9) {
- *mret = NULL;
- return slen;
- }
-
- /* Don't generate compressed packets which are larger than
- the uncompressed packet. */
- if (maxolen > slen)
- maxolen = slen;
-
- /* Allocate one mbuf to start with. */
- MGET(m, M_DONTWAIT, MT_DATA);
- *mret = m;
- if (m != NULL) {
- m->m_len = 0;
- if (maxolen + db->hdrlen > MLEN)
- MCLGET(m, M_DONTWAIT);
- m->m_data += db->hdrlen;
- wptr = mtod(m, u_char *);
- cp_end = wptr + M_TRAILINGSPACE(m);
- } else
- wptr = cp_end = NULL;
-
- /*
- * Copy the PPP header over, changing the protocol,
- * and install the 2-byte packet sequence number.
- */
- if (wptr) {
- *wptr++ = PPP_ADDRESS(rptr); /* assumes the ppp header is */
- *wptr++ = PPP_CONTROL(rptr); /* all in one mbuf */
- *wptr++ = 0; /* change the protocol */
- *wptr++ = PPP_COMP;
- *wptr++ = db->seqno >> 8;
- *wptr++ = db->seqno;
- }
- ++db->seqno;
-
- olen = 0;
- rptr += PPP_HDRLEN;
- slen = mp->m_len - PPP_HDRLEN;
- ilen = slen + 1;
- for (;;) {
- if (slen <= 0) {
- mp = mp->m_next;
- if (!mp)
- break;
- rptr = mtod(mp, u_char *);
- slen = mp->m_len;
- if (!slen)
- continue; /* handle 0-length buffers */
- ilen += slen;
- }
-
- slen--;
- c = *rptr++;
- fcode = BSD_KEY(ent, c);
- hval = BSD_HASH(ent, c, hshift);
- dictp = &db->dict[hval];
-
- /* Validate and then check the entry. */
- if (dictp->codem1 >= max_ent)
- goto nomatch;
- if (dictp->f.fcode == fcode) {
- ent = dictp->codem1+1;
- continue; /* found (prefix,suffix) */
- }
-
- /* continue probing until a match or invalid entry */
- disp = (hval == 0) ? 1 : hval;
- do {
- hval += disp;
- if (hval >= db->hsize)
- hval -= db->hsize;
- dictp = &db->dict[hval];
- if (dictp->codem1 >= max_ent)
- goto nomatch;
- } while (dictp->f.fcode != fcode);
- ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
- continue;
-
- nomatch:
- OUTPUT(ent); /* output the prefix */
-
- /* code -> hashtable */
- if (max_ent < db->maxmaxcode) {
- struct bsd_dict *dictp2;
- /* expand code size if needed */
- if (max_ent >= MAXCODE(n_bits))
- db->n_bits = ++n_bits;
-
- /* Invalidate old hash table entry using
- * this code, and then take it over.
- */
- dictp2 = &db->dict[max_ent+1];
- if (db->dict[dictp2->cptr].codem1 == max_ent)
- db->dict[dictp2->cptr].codem1 = BADCODEM1;
- dictp2->cptr = hval;
- dictp->codem1 = max_ent;
- dictp->f.fcode = fcode;
-
- db->max_ent = ++max_ent;
- }
- ent = c;
- }
-
- OUTPUT(ent); /* output the last code */
- db->bytes_out += olen;
- db->in_count += ilen;
- if (bitno < 32)
- ++db->bytes_out; /* count complete bytes */
-
- if (bsd_check(db))
- OUTPUT(CLEAR); /* do not count the CLEAR */
-
- /*
- * Pad dribble bits of last code with ones.
- * Do not emit a completely useless byte of ones.
- */
- if (bitno != 32)
- PUTBYTE((accm | (0xff << (bitno-8))) >> 24);
-
- if (m != NULL) {
- m->m_len = wptr - mtod(m, u_char *);
- m->m_next = NULL;
- }
-
- /*
- * Increase code size if we would have without the packet
- * boundary and as the decompressor will.
- */
- if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
- db->n_bits++;
-
- db->uncomp_bytes += ilen;
- ++db->uncomp_count;
- if (olen + PPP_HDRLEN + BSD_OVHD > maxolen) {
- /* throw away the compressed stuff if it is longer than uncompressed */
- if (*mret != NULL) {
- m_freem(*mret);
- *mret = NULL;
- }
- ++db->incomp_count;
- db->incomp_bytes += ilen;
- } else {
- ++db->comp_count;
- db->comp_bytes += olen + BSD_OVHD;
- }
-
- return olen + PPP_HDRLEN + BSD_OVHD;
-#undef OUTPUT
-#undef PUTBYTE
-}
-
-
-/*
- * Update the "BSD Compress" dictionary on the receiver for
- * incompressible data by pretending to compress the incoming data.
- */
-static void
-bsd_incomp(state, dmsg)
- void *state;
- struct mbuf *dmsg;
-{
- struct bsd_db *db = (struct bsd_db *) state;
- u_int hshift = db->hshift;
- u_int max_ent = db->max_ent;
- u_int n_bits = db->n_bits;
- struct bsd_dict *dictp;
- u_int32_t fcode;
- u_char c;
- u_int32_t hval, disp;
- int slen, ilen;
- u_int bitno = 7;
- u_char *rptr;
- u_int ent;
-
- /*
- * If the protocol is not in the range we're interested in,
- * just return without looking at the packet. If it is,
- * the protocol becomes the first byte to "compress".
- */
- rptr = mtod(dmsg, u_char *);
- ent = PPP_PROTOCOL(rptr);
- if (ent < 0x21 || ent > 0xf9)
- return;
-
- db->incomp_count++;
- db->seqno++;
- ilen = 1; /* count the protocol as 1 byte */
- rptr += PPP_HDRLEN;
- slen = dmsg->m_len - PPP_HDRLEN;
- for (;;) {
- if (slen <= 0) {
- dmsg = dmsg->m_next;
- if (!dmsg)
- break;
- rptr = mtod(dmsg, u_char *);
- slen = dmsg->m_len;
- continue;
- }
- ilen += slen;
-
- do {
- c = *rptr++;
- fcode = BSD_KEY(ent, c);
- hval = BSD_HASH(ent, c, hshift);
- dictp = &db->dict[hval];
-
- /* validate and then check the entry */
- if (dictp->codem1 >= max_ent)
- goto nomatch;
- if (dictp->f.fcode == fcode) {
- ent = dictp->codem1+1;
- continue; /* found (prefix,suffix) */
- }
-
- /* continue probing until a match or invalid entry */
- disp = (hval == 0) ? 1 : hval;
- do {
- hval += disp;
- if (hval >= db->hsize)
- hval -= db->hsize;
- dictp = &db->dict[hval];
- if (dictp->codem1 >= max_ent)
- goto nomatch;
- } while (dictp->f.fcode != fcode);
- ent = dictp->codem1+1;
- continue; /* finally found (prefix,suffix) */
-
- nomatch: /* output (count) the prefix */
- bitno += n_bits;
-
- /* code -> hashtable */
- if (max_ent < db->maxmaxcode) {
- struct bsd_dict *dictp2;
- /* expand code size if needed */
- if (max_ent >= MAXCODE(n_bits))
- db->n_bits = ++n_bits;
-
- /* Invalidate previous hash table entry
- * assigned this code, and then take it over.
- */
- dictp2 = &db->dict[max_ent+1];
- if (db->dict[dictp2->cptr].codem1 == max_ent)
- db->dict[dictp2->cptr].codem1 = BADCODEM1;
- dictp2->cptr = hval;
- dictp->codem1 = max_ent;
- dictp->f.fcode = fcode;
-
- db->max_ent = ++max_ent;
- db->lens[max_ent] = db->lens[ent]+1;
- }
- ent = c;
- } while (--slen != 0);
- }
- bitno += n_bits; /* output (count) the last code */
- db->bytes_out += bitno/8;
- db->in_count += ilen;
- (void)bsd_check(db);
-
- ++db->incomp_count;
- db->incomp_bytes += ilen;
- ++db->uncomp_count;
- db->uncomp_bytes += ilen;
-
- /* Increase code size if we would have without the packet
- * boundary and as the decompressor will.
- */
- if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode)
- db->n_bits++;
-}
-
-
-/*
- * Decompress "BSD Compress".
- *
- * Because of patent problems, we return DECOMP_ERROR for errors
- * found by inspecting the input data and for system problems, but
- * DECOMP_FATALERROR for any errors which could possibly be said to
- * be being detected "after" decompression. For DECOMP_ERROR,
- * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
- * infringing a patent of Motorola's if we do, so we take CCP down
- * instead.
- *
- * Given that the frame has the correct sequence number and a good FCS,
- * errors such as invalid codes in the input most likely indicate a
- * bug, so we return DECOMP_FATALERROR for them in order to turn off
- * compression, even though they are detected by inspecting the input.
- */
-int
-bsd_decompress(state, cmp, dmpp)
- void *state;
- struct mbuf *cmp, **dmpp;
-{
- struct bsd_db *db = (struct bsd_db *) state;
- u_int max_ent = db->max_ent;
- u_int32_t accm = 0;
- u_int bitno = 32; /* 1st valid bit in accm */
- u_int n_bits = db->n_bits;
- u_int tgtbitno = 32-n_bits; /* bitno when we have a code */
- struct bsd_dict *dictp;
- int explen, i, seq, len;
- u_int incode, oldcode, finchar;
- u_char *p, *rptr, *wptr;
- struct mbuf *m, *dmp, *mret;
- int adrs, ctrl, ilen;
- int space, codelen, extra;
- struct mbuf *last;
-
- /*
- * Save the address/control from the PPP header
- * and then get the sequence number.
- */
- *dmpp = NULL;
- rptr = mtod(cmp, u_char *);
- adrs = PPP_ADDRESS(rptr);
- ctrl = PPP_CONTROL(rptr);
- rptr += PPP_HDRLEN;
- len = cmp->m_len - PPP_HDRLEN;
- seq = 0;
- for (i = 0; i < 2; ++i) {
- while (len <= 0) {
- cmp = cmp->m_next;
- if (cmp == NULL)
- return DECOMP_ERROR;
- rptr = mtod(cmp, u_char *);
- len = cmp->m_len;
- }
- seq = (seq << 8) + *rptr++;
- --len;
- }
-
- /*
- * Check the sequence number and give up if it differs from
- * the value we're expecting.
- */
- if (seq != db->seqno) {
- if (db->debug)
- printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
- db->unit, seq, db->seqno - 1);
- return DECOMP_ERROR;
- }
- ++db->seqno;
-
- /*
- * Allocate one mbuf to start with.
- */
- MGETHDR(dmp, M_DONTWAIT, MT_DATA);
- if (dmp == NULL)
- return DECOMP_ERROR;
- mret = dmp;
- dmp->m_len = 0;
- dmp->m_next = NULL;
- MCLGET(dmp, M_DONTWAIT);
- dmp->m_data += db->hdrlen;
- wptr = mtod(dmp, u_char *);
- space = M_TRAILINGSPACE(dmp) - PPP_HDRLEN + 1;
-
- /*
- * Fill in the ppp header, but not the last byte of the protocol
- * (that comes from the decompressed data).
- */
- wptr[0] = adrs;
- wptr[1] = ctrl;
- wptr[2] = 0;
- wptr += PPP_HDRLEN - 1;
-
- ilen = len;
- oldcode = CLEAR;
- explen = 0;
- for (;;) {
- if (len == 0) {
- cmp = cmp->m_next;
- if (!cmp) /* quit at end of message */
- break;
- rptr = mtod(cmp, u_char *);
- len = cmp->m_len;
- ilen += len;
- continue; /* handle 0-length buffers */
- }
-
- /*
- * Accumulate bytes until we have a complete code.
- * Then get the next code, relying on the 32-bit,
- * unsigned accm to mask the result.
- */
- bitno -= 8;
- accm |= *rptr++ << bitno;
- --len;
- if (tgtbitno < bitno)
- continue;
- incode = accm >> tgtbitno;
- accm <<= n_bits;
- bitno += n_bits;
-
- if (incode == CLEAR) {
- /*
- * The dictionary must only be cleared at
- * the end of a packet. But there could be an
- * empty mbuf at the end.
- */
- if (len > 0 || cmp->m_next != NULL) {
- while ((cmp = cmp->m_next) != NULL)
- len += cmp->m_len;
- if (len > 0) {
- m_freem(mret);
- if (db->debug)
- printf("bsd_decomp%d: bad CLEAR\n", db->unit);
- return DECOMP_FATALERROR; /* probably a bug */
- }
- }
- bsd_clear(db);
- explen = ilen = 0;
- break;
- }
-
- if (incode > max_ent + 2 || incode > db->maxmaxcode
- || incode > max_ent && oldcode == CLEAR) {
- m_freem(mret);
- if (db->debug) {
- printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
- db->unit, incode, oldcode);
- printf("max_ent=0x%x explen=%d seqno=%d\n",
- max_ent, explen, db->seqno);
- }
- return DECOMP_FATALERROR; /* probably a bug */
- }
-
- /* Special case for KwKwK string. */
- if (incode > max_ent) {
- finchar = oldcode;
- extra = 1;
- } else {
- finchar = incode;
- extra = 0;
- }
-
- codelen = db->lens[finchar];
- explen += codelen + extra;
- if (explen > db->mru + 1) {
- m_freem(mret);
- if (db->debug) {
- printf("bsd_decomp%d: ran out of mru\n", db->unit);
-#ifdef DEBUG
- while ((cmp = cmp->m_next) != NULL)
- len += cmp->m_len;
- printf(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n",
- len, finchar, codelen, explen);
-#endif
- }
- return DECOMP_FATALERROR;
- }
-
- /*
- * For simplicity, the decoded characters go in a single mbuf,
- * so we allocate a single extra cluster mbuf if necessary.
- */
- if ((space -= codelen + extra) < 0) {
- dmp->m_len = wptr - mtod(dmp, u_char *);
- MGET(m, M_DONTWAIT, MT_DATA);
- if (m == NULL) {
- m_freem(mret);
- return DECOMP_ERROR;
- }
- m->m_len = 0;
- m->m_next = NULL;
- dmp->m_next = m;
- MCLGET(m, M_DONTWAIT);
- space = M_TRAILINGSPACE(m) - (codelen + extra);
- if (space < 0) {
- /* now that's what I call *compression*. */
- m_freem(mret);
- return DECOMP_ERROR;
- }
- dmp = m;
- wptr = mtod(dmp, u_char *);
- }
-
- /*
- * Decode this code and install it in the decompressed buffer.
- */
- p = (wptr += codelen);
- while (finchar > LAST) {
- dictp = &db->dict[db->dict[finchar].cptr];
-#ifdef DEBUG
- if (--codelen <= 0 || dictp->codem1 != finchar-1)
- goto bad;
-#endif
- *--p = dictp->f.hs.suffix;
- finchar = dictp->f.hs.prefix;
- }
- *--p = finchar;
-
-#ifdef DEBUG
- if (--codelen != 0)
- printf("bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n",
- db->unit, codelen, incode, max_ent);
-#endif
-
- if (extra) /* the KwKwK case again */
- *wptr++ = finchar;
-
- /*
- * If not first code in a packet, and
- * if not out of code space, then allocate a new code.
- *
- * Keep the hash table correct so it can be used
- * with uncompressed packets.
- */
- if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
- struct bsd_dict *dictp2;
- u_int32_t fcode;
- u_int32_t hval, disp;
-
- fcode = BSD_KEY(oldcode,finchar);
- hval = BSD_HASH(oldcode,finchar,db->hshift);
- dictp = &db->dict[hval];
-
- /* look for a free hash table entry */
- if (dictp->codem1 < max_ent) {
- disp = (hval == 0) ? 1 : hval;
- do {
- hval += disp;
- if (hval >= db->hsize)
- hval -= db->hsize;
- dictp = &db->dict[hval];
- } while (dictp->codem1 < max_ent);
- }
-
- /*
- * Invalidate previous hash table entry
- * assigned this code, and then take it over
- */
- dictp2 = &db->dict[max_ent+1];
- if (db->dict[dictp2->cptr].codem1 == max_ent) {
- db->dict[dictp2->cptr].codem1 = BADCODEM1;
- }
- dictp2->cptr = hval;
- dictp->codem1 = max_ent;
- dictp->f.fcode = fcode;
-
- db->max_ent = ++max_ent;
- db->lens[max_ent] = db->lens[oldcode]+1;
-
- /* Expand code size if needed. */
- if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
- db->n_bits = ++n_bits;
- tgtbitno = 32-n_bits;
- }
- }
- oldcode = incode;
- }
- dmp->m_len = wptr - mtod(dmp, u_char *);
-
- /*
- * Keep the checkpoint right so that incompressible packets
- * clear the dictionary at the right times.
- */
- db->bytes_out += ilen;
- db->in_count += explen;
- if (bsd_check(db) && db->debug) {
- printf("bsd_decomp%d: peer should have cleared dictionary\n",
- db->unit);
- }
-
- ++db->comp_count;
- db->comp_bytes += ilen + BSD_OVHD;
- ++db->uncomp_count;
- db->uncomp_bytes += explen;
-
- *dmpp = mret;
- return DECOMP_OK;
-
-#ifdef DEBUG
- bad:
- if (codelen <= 0) {
- printf("bsd_decomp%d: fell off end of chain ", db->unit);
- printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
- incode, finchar, db->dict[finchar].cptr, max_ent);
- } else if (dictp->codem1 != finchar-1) {
- printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",
- db->unit, incode, finchar);
- printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
- db->dict[finchar].cptr, dictp->codem1);
- }
- m_freem(mret);
- return DECOMP_FATALERROR;
-#endif /* DEBUG */
-}
-#endif /* DO_BSD_COMPRESS */
projects / ppp.git / commitdiff