--- /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.
+ */
+
+/*
+ * This version is for use with STREAMS under SunOS 4.x.
+ */
+
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/stream.h>
+#include <sys/kmem_alloc.h>
+#include <net/ppp_str.h>
+
+#define PACKET mblk_t
+#include <net/ppp-comp.h>
+
+/*
+ * 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 */
+ char debug;
+ u_char unit;
+ u_short mru;
+ u_int maxmaxcode; /* largest valid code */
+ u_int max_ent; /* largest code in use */
+ u_long seqno; /* # of last byte of packet */
+ u_long in_count; /* uncompressed bytes */
+ u_long bytes_out; /* compressed bytes */
+ u_long ratio; /* recent compression ratio */
+ u_long checkpoint; /* when to next check the ratio */
+ int clear_count; /* times dictionary cleared */
+ int incomp_count; /* incompressible packets */
+ u_short *lens; /* array of lengths of codes */
+ struct bsd_dict {
+ union { /* hash value */
+ u_long fcode;
+ struct {
+#ifdef BSD_LITTLE_ENDIAN
+ u_short 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_short prefix; /* preceding code */
+#endif
+ } hs;
+ } f;
+ u_short codem1; /* output of hash table -1 */
+ u_short cptr; /* map code to hash table entry */
+ } dict[1];
+};
+
+#define BSD_OVHD 3 /* BSD compress overhead/packet */
+#define MIN_BSD_BITS 9
+#define BSD_INIT_BITS MIN_BSD_BITS
+#define MAX_BSD_BITS 15
+
+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 debug));
+static int bsd_decomp_init __P((void *state, u_char *options, int opt_len,
+ int unit, int mru, int debug));
+static int bsd_compress __P((void *state, mblk_t **mret,
+ mblk_t *mp, int slen, int maxolen));
+static void bsd_incomp __P((void *state, mblk_t *dmsg));
+static mblk_t *bsd_decompress __P((void *state, mblk_t *cmp, int hdroff));
+static void bsd_reset __P((void *state));
+
+/*
+ * Procedures exported to ppp_comp.c.
+ */
+struct compressor ppp_bsd_compress = {
+ 0x21, /* compress_proto */
+ bsd_comp_alloc, /* comp_alloc */
+ bsd_free, /* comp_free */
+ bsd_comp_init, /* comp_init */
+ bsd_reset, /* comp_reset */
+ bsd_compress, /* compress */
+ bsd_decomp_alloc, /* decomp_alloc */
+ bsd_free, /* decomp_free */
+ bsd_decomp_init, /* decomp_init */
+ bsd_reset, /* decomp_reset */
+ bsd_decompress, /* decompress */
+ bsd_incomp, /* incomp */
+};
+
+/*
+ * 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(MAX_BSD_BITS);
+
+#define BSD_HASH(prefix,suffix,hshift) ((((u_long)(suffix)) << (hshift)) \
+ ^ (u_long)(prefix))
+#define BSD_KEY(prefix,suffix) ((((u_long)(suffix)) << 16) + (u_long)(prefix))
+
+#define CHECK_GAP 10000 /* Ratio check interval */
+
+
+/*
+ * 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_long new_ratio;
+
+ if (db->in_count >= db->checkpoint) {
+ /* age the ratio by limiting the size of the counts */
+ if (db->in_count >= 0x7fffff
+ || db->bytes_out >= 0x7fffff) {
+ 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 <= 0x7fffff.
+ */
+ new_ratio = db->in_count<<8;
+ if (db->bytes_out != 0)
+ new_ratio /= db->bytes_out;
+
+ if (new_ratio < db->ratio || new_ratio < 256) {
+ bsd_clear(db);
+ return 1;
+ }
+ db->ratio = new_ratio;
+ }
+ }
+ return 0;
+}
+
+/*
+ * 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 != 3 || options[0] != 0x21 || options[1] != 3)
+ return NULL;
+ bits = 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]));
+ db = (struct bsd_db *) kmem_alloc(newlen, KMEM_NOSLEEP);
+ if (!db)
+ return NULL;
+ bzero(db, sizeof(*db) - sizeof(db->dict));
+
+ if (!decomp) {
+ db->lens = NULL;
+ } else {
+ db->lens = (u_short *) kmem_alloc((maxmaxcode+1) * sizeof(db->lens[0]),
+ KMEM_NOSLEEP);
+ if (!db->lens) {
+ kmem_free(db, newlen);
+ return NULL;
+ }
+ }
+
+ db->totlen = newlen;
+ db->hsize = hsize;
+ db->hshift = hshift;
+ db->maxmaxcode = maxmaxcode;
+
+ return (void *) db;
+}
+
+static void
+bsd_free(state)
+ void *state;
+{
+ struct bsd_db *db = (struct bsd_db *) state;
+
+ if (db->lens)
+ kmem_free(db->lens, (db->maxmaxcode+1) * sizeof(db->lens[0]));
+ kmem_free(db, db->totlen);
+}
+
+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, mru, debug, decomp)
+ struct bsd_db *db;
+ u_char *options;
+ int opt_len, unit, mru, debug, decomp;
+{
+ int i;
+
+ if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
+ || MAXCODE(options[2]) != db->maxmaxcode
+ || 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->mru = mru;
+ db->clear_count = -1;
+ if (debug)
+ db->debug = 1;
+
+ bsd_clear(db);
+
+ return 1;
+}
+
+static int
+bsd_comp_init(state, options, opt_len, unit, debug)
+ void *state;
+ u_char *options;
+ int opt_len, unit, debug;
+{
+ return bsd_init((struct bsd_db *) state, options, opt_len,
+ unit, 0, debug, 0);
+}
+
+static int
+bsd_decomp_init(state, options, opt_len, unit, mru, debug)
+ void *state;
+ u_char *options;
+ int opt_len, unit, mru, debug;
+{
+ return bsd_init((struct bsd_db *) state, options, opt_len,
+ unit, mru, debug, 1);
+}
+
+
+
+/*
+ * compress a packet
+ * Assume the protocol is known to be >= 0x21 and < 0xff.
+ * One change from the BSD compress command is that when the
+ * code size expands, we do not output a bunch of padding.
+ */
+static int /* new slen */
+bsd_compress(state, mret, mp, slen, maxolen)
+ void *state;
+ mblk_t **mret; /* return compressed mbuf chain here */
+ mblk_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_long accm = 0;
+ struct bsd_dict *dictp;
+ u_long fcode;
+ u_char c;
+ long hval, disp, ent;
+ mblk_t *np;
+ u_char *rptr, *wptr;
+ u_char *cp_end;
+ int olen;
+ mblk_t *m, **mnp;
+ int proto;
+
+#define PUTBYTE(v) { \
+ if (wptr) { \
+ *wptr++ = (v); \
+ if (wptr >= cp_end) { \
+ m->b_wptr = wptr; \
+ m = m->b_cont; \
+ if (m) { \
+ wptr = m->b_wptr; \
+ cp_end = m->b_datap->db_lim; \
+ } else \
+ wptr = NULL; \
+ } \
+ } \
+ ++olen; \
+}
+
+#define OUTPUT(ent) { \
+ bitno -= n_bits; \
+ accm |= ((ent) << bitno); \
+ do { \
+ PUTBYTE(accm >> 24); \
+ accm <<= 8; \
+ bitno += 8; \
+ } while (bitno <= 24); \
+}
+
+ /* Don't generate compressed packets which are larger than
+ the uncompressed packet. */
+ if (maxolen > slen)
+ maxolen = slen;
+
+ /* Allocate enough message blocks to give maxolen total space. */
+ mnp = mret;
+ for (olen = maxolen; olen > 0; ) {
+ m = allocb((olen < 4096? olen: 4096), BPRI_MED);
+ *mnp = m;
+ if (m == NULL) {
+ if (*mret != NULL) {
+ freemsg(*mret);
+ mnp = mret;
+ }
+ break;
+ }
+ mnp = &m->b_cont;
+ olen -= m->b_datap->db_lim - m->b_wptr;
+ }
+ *mnp = NULL;
+
+ rptr = mp->b_rptr;
+ if ((m = *mret) != NULL) {
+ wptr = m->b_wptr;
+ cp_end = m->b_datap->db_lim;
+ } else
+ wptr = cp_end = NULL;
+ olen = 0;
+
+ /* Copy the PPP header over, changing the protocol */
+ if (wptr) {
+ *wptr++ = rptr[0]; /* assumes the ppp header is */
+ *wptr++ = rptr[1]; /* all in one mblk */
+ *wptr++ = 0; /* change the protocol */
+ *wptr++ = PPP_COMP;
+ }
+
+ /* install the 3-byte sequence number */
+ slen += db->seqno - PPP_HDRLEN + 1;
+ db->seqno = slen;
+ *wptr++ = slen>>16;
+ *wptr++ = slen>>8;
+ *wptr++ = slen;
+
+ /* start with the protocol byte */
+ ent = rptr[3];
+ rptr += PPP_HDRLEN;
+ slen = mp->b_wptr - rptr;
+ db->in_count += slen + 1;
+ np = mp->b_cont;
+ for (;;) {
+ if (slen <= 0) {
+ if (!np)
+ break;
+ rptr = np->b_rptr;
+ slen = np->b_wptr - rptr;
+ np = np->b_cont;
+ if (!slen)
+ continue; /* handle 0-length buffers */
+ db->in_count += 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;
+
+ 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++;
+
+ if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && *mret != NULL) {
+ /* throw away the compressed stuff if it is longer than uncompressed */
+ freemsg(*mret);
+ *mret = NULL;
+ } else if (wptr != NULL) {
+ m->b_wptr = wptr;
+ if (m->b_cont) {
+ freemsg(m->b_cont);
+ m->b_cont = NULL;
+ }
+ }
+
+ 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.
+ * The protocol is assumed to be < 0x100.
+ */
+static void
+bsd_incomp(state, dmsg)
+ void *state;
+ mblk_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_long fcode;
+ u_char c;
+ long hval, disp;
+ int slen;
+ u_int bitno = 7;
+ u_char *rptr;
+ u_int ent;
+
+ db->incomp_count++;
+
+ db->seqno++;
+ db->in_count++; /* count the protocol as 1 byte */
+ rptr = dmsg->b_rptr;
+ ent = rptr[3]; /* get the protocol */
+ rptr += PPP_HDRLEN;
+ for (;;) {
+ slen = dmsg->b_wptr - rptr;
+ if (slen <= 0) {
+ dmsg = dmsg->b_cont;
+ if (!dmsg)
+ break;
+ rptr = dmsg->b_rptr;
+ continue; /* skip zero-length buffers */
+ }
+ db->in_count += slen;
+ db->seqno += 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;
+ (void)bsd_check(db);
+
+ /* 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"
+ */
+static mblk_t * /* 0=failed, so zap CCP */
+bsd_decompress(state, cmsg, hdroff)
+ void *state;
+ mblk_t *cmsg;
+ int hdroff;
+{
+ struct bsd_db *db = (struct bsd_db *) state;
+ u_int max_ent = db->max_ent;
+ u_long 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;
+ mblk_t *dmsg;
+ int adrs, ctrl;
+ int dlen, space, codelen;
+
+ /*
+ * Get at least the BSD Compress header in the first buffer
+ */
+ rptr = cmsg->b_rptr;
+ if (rptr + PPP_HDRLEN + BSD_OVHD <= cmsg->b_wptr) {
+ if (!pullupmsg(cmsg, PPP_HDRLEN + BSD_OVHD + 1)) {
+ if (db->debug)
+ printf("bsd_decomp%d: failed to pullup\n", db->unit);
+ return 0;
+ }
+ rptr = cmsg->b_rptr;
+ }
+
+ /*
+ * Save the address/control from the PPP header
+ * and then get the sequence number.
+ */
+ adrs = PPP_ADDRESS(rptr);
+ ctrl = PPP_CONTROL(rptr);
+ rptr += PPP_HDRLEN;
+ seq = (rptr[0] << 16) + (rptr[1] << 8) + rptr[2];
+ rptr += 3;
+ len = cmsg->b_wptr - rptr;
+
+ /* check the sequence number and give up if the length is nonsense */
+ explen = (seq - db->seqno) & 0xffffff;
+ db->seqno = seq;
+ if (explen > db->mru || explen < 1) {
+ if (db->debug)
+ printf("bsd_decomp%d: bad length 0x%x\n", db->unit, explen);
+ return 0;
+ }
+
+ /* allocate enough message blocks for the decompressed message */
+ dlen = explen + PPP_HDRLEN - 1 + hdroff;
+ /* XXX assume decompressed packet fits in a single block */
+ dmsg = allocb(dlen, BPRI_HI);
+ if (!dmsg) {
+ /* give up if cannot get an uncompressed buffer */
+ return 0;
+ }
+ wptr = dmsg->b_wptr;
+
+ /* 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;
+ space = dmsg->b_datap->db_lim - wptr;
+
+ db->bytes_out += len;
+ dlen = explen;
+ oldcode = CLEAR;
+ for (;;) {
+ if (len == 0) {
+ cmsg = cmsg->b_cont;
+ if (!cmsg) { /* quit at end of message */
+ if (dlen != 0) {
+ freemsg(dmsg);
+ if (db->debug)
+ printf("bsd_decomp%d: lost %d bytes\n",
+ db->unit, explen);
+ return 0;
+ }
+ break;
+ }
+ rptr = cmsg->b_rptr;
+ len = cmsg->b_wptr - rptr;
+ db->bytes_out += 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 message block at the end.
+ */
+ if (len > 0 || cmsg->b_cont != 0) {
+ if (cmsg->b_cont)
+ len += msgdsize(cmsg->b_cont);
+ if (len > 0) {
+ freemsg(dmsg);
+ if (db->debug)
+ printf("bsd_decomp%d: bad CLEAR\n", db->unit);
+ return 0;
+ }
+ }
+ bsd_clear(db);
+ explen = 0;
+ break;
+ }
+
+ /* Special case for KwKwK string. */
+ if (incode > max_ent) {
+ if (incode > max_ent+2 || incode > db->maxmaxcode
+ || oldcode == CLEAR) {
+ freemsg(dmsg);
+ if (db->debug) {
+ printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
+ db->unit, incode, oldcode);
+ printf("max_ent=0x%x dlen=%d seqno=%d\n",
+ max_ent, dlen, db->seqno);
+ }
+ return 0;
+ }
+ finchar = oldcode;
+ --dlen;
+ } else
+ finchar = incode;
+
+ codelen = db->lens[finchar];
+ dlen -= codelen;
+ if (dlen < 0) {
+ freemsg(dmsg);
+ if (db->debug)
+ printf("bsd_decomp%d: ran out of buffer\n", db->unit);
+ return 0;
+ }
+
+ /* decode code and install in decompressed buffer */
+ space -= codelen;
+ if (space < 0) {
+#ifdef DEBUG
+ if (cmsg->b_cont)
+ len += msgdsize(cmsg->b_cont);
+ printf("bsd_decomp%d: overran output by %d with %d bytes left\n",
+ db->unit, -space, len);
+#endif
+ freemsg(dmsg);
+ return 0;
+ }
+ p = (wptr += codelen);
+ while (finchar > LAST) {
+ dictp = &db->dict[db->dict[finchar].cptr];
+#ifdef DEBUG
+ --codelen;
+ if (codelen <= 0) {
+ freemsg(dmsg);
+ 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);
+ return 0;
+ }
+ if (dictp->codem1 != finchar-1) {
+ freemsg(dmsg);
+ 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);
+ return 0;
+ }
+#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 (incode > max_ent) { /* the KwKwK case again */
+ *wptr++ = finchar;
+ --space;
+ }
+
+ /*
+ * 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_long fcode;
+ long 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;
+ }
+ dmsg->b_wptr = wptr;
+
+ /* fail on packets with bad lengths/sequence numbers */
+ if (dlen != 0) {
+ freemsg(dmsg);
+ return 0;
+ }
+
+ /* Keep the checkpoint right so that incompressible packets
+ * clear the dictionary at the right times.
+ */
+ db->in_count += explen;
+ if (bsd_check(db) && db->debug) {
+ printf("bsd_decomp%d: peer should have cleared dictionary\n",
+ db->unit);
+ }
+
+ return dmsg;
+}
projects / ppp.git / commitdiff