--- /dev/null
+/* 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.
+ *
+ * Rewritten for NextStep's funky kernel functions, I/O threads,
+ * and netbufs (instead of real mbufs). Also, ifnets don't install
+ * into the kernel under NS as they do under BSD. We have tried to
+ * make the code remain as similar to the NetBSD version without
+ * incurring too much hassle. This code is the merge of
+ * Philip Prindeville's <philipp@res.enst.fr>/Pete French's <pete@ohm.york.ac.uk>
+ * and Stephen Perkins' <perkins@cps.msu.edu> independent ports.
+ *
+ */
+
+/*
+ * This version is for use with mbufs on BSD-derived systems.
+ *
+ * $Id: bsd-comp.c,v 1.1 1995/12/18 03:30:00 paulus Exp $
+ */
+
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#define KERNEL 1
+#include <net/netbuf.h>
+#include <net/if.h>
+
+#include <net/ppp_defs.h>
+#include <net/if_ppp.h>
+
+#define PACKETPTR netbuf_t
+#include <net/ppp-comp.h>
+
+#include "nbq.h"
+
+/*
+ * We align with this number of bits zero. The code makes the somewhat
+ * suspect assumption that an address can be held in an unsigned long.
+ * Sadly this is necessary to do bit operations on it.
+ */
+
+#define Z_ALIGN 3 /* 8 byte boudary */
+#define Z_EXTRA ((unsigned long)((1<<Z_ALIGN)-1))
+#define ALIGN(x) ((x+Z_EXTRA) & ~Z_EXTRA)
+
+#if DO_BSD_COMPRESS
+
+/*
+ * The following includes are necessary to correctly
+ * support BYTE_ORDER. -SJP
+ */
+
+#include <netinet/in.h>
+#include <netinet/in_systm.h>
+#include <netinet/in_var.h>
+#include <netinet/ip.h>
+
+#define mtod(m,type) ((type)nb_map(m))
+typedef unsigned short u_int16_t;
+
+/*
+ * 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 {
+ void *kbase; /* actual kalloc'd address for struct */
+ void *klens; /* actual kalloc'd address for lens */
+ 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, netbuf_t *mret,
+ netbuf_t mp, int slen, int maxolen));
+static void bsd_incomp __P((void *state, netbuf_t dmsg));
+static int bsd_decompress __P((void *state, netbuf_t cmp, netbuf_t *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)
+
+/* Could include inlines.h */
+#ifndef IOLog
+#define IOLog printf
+#define IOLogDbg if (db->debug) printf
+#else
+#define IOLogDbg if (db->debug) IOLog
+#endif
+
+/*
+ * 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]));
+ {
+ unsigned long kret;
+ kret = (unsigned long) kalloc(Z_EXTRA + newlen);
+ if (!kret)
+ return NULL;
+ db = (struct bsd_db *) ALIGN(kret);
+ bzero(db, sizeof(*db) - sizeof(db->dict));
+ db->kbase = (void *)kret;
+ }
+
+ if (!decomp) {
+ db->lens = NULL;
+ } else {
+ unsigned long kret;
+ kret = (unsigned long) kalloc(Z_EXTRA +
+ ((maxmaxcode+1) * sizeof(db->lens[0])));
+ if (!kret) {
+ kfree(db->kbase, newlen + Z_EXTRA);
+ return NULL;
+ }
+ db->lens = (u_int16_t *) ALIGN(kret);
+ db->klens = (void *) kret;
+ }
+
+ 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)
+ kfree(db->klens, ((db->maxmaxcode+1) * sizeof(db->lens[0])) + Z_EXTRA);
+ kfree(db->kbase, db->totlen + Z_EXTRA);
+}
+
+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;
+ netbuf_t *mret; /* return compressed netbuf here */
+ netbuf_t 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;
+ u_char *rptr, *wptr;
+ u_char *cp_end;
+ int olen;
+ netbuf_t m;
+
+#define PUTBYTE(v) { \
+ ++olen; \
+ if (wptr) { \
+ *wptr++ = (v); \
+ if (wptr >= cp_end) \
+ 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 < CI_BSD_COMPRESS || 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. (don't forget space for the FCS!) */
+ m = ppp_nb_alloc(maxolen + db->hdrlen + PPP_FCSLEN);
+ *mret = m;
+ if (m != NULL) {
+ if (db->hdrlen > 0)
+ ppp_nb_shrink_top(m, db->hdrlen);
+ nb_shrink_bot(m, PPP_FCSLEN); /* grown by pppstart() */
+ wptr = mtod(m, u_char *);
+ cp_end = wptr + maxolen;
+ } 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 = nb_size(mp) - PPP_HDRLEN;
+ ilen = slen + 1;
+ while (slen > 0) {
+ 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);
+
+ /*
+ * 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 || wptr == NULL) {
+ /* throw away the compressed stuff if it is longer than uncompressed */
+ if (*mret != NULL) {
+ nb_free(*mret);
+ *mret = NULL;
+ }
+ ++db->incomp_count;
+ db->incomp_bytes += ilen;
+ } else {
+ nb_shrink_bot(m, nb_size(m) - (wptr - mtod(m, u_char *)));
+ ++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;
+ netbuf_t 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 < CI_BSD_COMPRESS || ent > 0xf9)
+ return;
+
+ db->incomp_count++;
+ db->seqno++;
+ ilen = 1; /* count the protocol as 1 byte */
+ rptr += PPP_HDRLEN;
+ slen = nb_size(dmsg) - PPP_HDRLEN;
+ 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;
+ netbuf_t 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, seq, len;
+ u_int incode, oldcode, finchar;
+ u_char *p, *rptr, *wptr;
+ netbuf_t dmp, mret;
+ int adrs, ctrl, ilen;
+ int space, codelen, extra, maxilen;
+
+ /*
+ * 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 = nb_size(cmp) - PPP_HDRLEN;
+ seq = (rptr[0] << 8) + rptr[1];
+ rptr += BSD_OVHD;
+ len -= BSD_OVHD;
+
+ /*
+ * Check the sequence number and give up if it differs from
+ * the value we're expecting.
+ */
+ if (seq != db->seqno) {
+ IOLogDbg("bsd_decomp%d: bad sequence # %d, expected %d\n",
+ db->unit, seq, db->seqno - 1);
+ return DECOMP_ERROR;
+ }
+ ++db->seqno;
+
+ /*
+ * Allocate an netbuf large enough for all the data.
+ */
+ maxilen = db->mru + db->hdrlen + PPP_HDRLEN; /* no FCS */
+ dmp = ppp_nb_alloc(maxilen); /* XXX */
+ if (dmp == NULL)
+ return DECOMP_ERROR;
+ if (db->hdrlen > 0)
+ ppp_nb_shrink_top(dmp, db->hdrlen);
+ mret = dmp;
+ wptr = mtod(dmp, u_char *);
+ space = nb_size(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;
+ while (len > 0) {
+ /*
+ * 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) {
+ nb_free(mret);
+ IOLogDbg("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) {
+ nb_free(mret);
+ IOLogDbg("bsd_decomp%d: bad code 0x%x oldcode=0x%x max_ent=0x%x explen=%d seqno=%d\n",
+ db->unit, incode, oldcode, 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) {
+ nb_free(mret);
+ IOLogDbg("bsd_decomp%d: ran out of mru\n len=%d, finchar=0x%x, codelen=%d, explen=%d\n",
+ db->unit, len, finchar, codelen, explen);
+ return DECOMP_FATALERROR;
+ }
+
+ /*
+ * If we have no space left, then we've overflowed...
+ */
+ if ((space -= codelen + extra) < 0) {
+ IOLog("bsd_decompress%d: no space left in netbuf (need %d bytes)\n",
+ db->unit, (codelen + extra) - space);
+ nb_free(mret);
+ return DECOMP_ERROR;
+ }
+
+ /*
+ * 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)
+ IOLog("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;
+ }
+ nb_shrink_bot(dmp, nb_size(dmp) - (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)) {
+ IOLogDbg("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) {
+ IOLog("bsd_decomp%d: fell off end of chain 0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
+ db->unit, incode, finchar, db->dict[finchar].cptr, max_ent);
+ } else if (dictp->codem1 != finchar-1) {
+ IOLog("bsd_decomp%d: bad code chain 0x%x finchar=0x%x oldcode=0x%x cptr=0x%x codem1=0x%x\n",
+ db->unit, incode, finchar, oldcode, db->dict[finchar].cptr,
+ dictp->codem1);
+ }
+ nb_free(mret);
+ return DECOMP_FATALERROR;
+#endif /* DEBUG */
+}
+#endif /* DO_BSD_COMPRESS */
projects / ppp.git / blobdiff