/*
* This version is for use with STREAMS under SunOS 4.x.
+ *
+ * $Id: bsd-comp.c,v 1.4 1994/09/16 02:06:31 paulus Exp $
*/
#include <sys/param.h>
* compression is not going well.
*/
+/*
+ * Macros to extract protocol version and number of bits
+ * from the third byte of the BSD Compress CCP configuration option.
+ */
+#define BSD_VERSION(x) ((x) >> 5)
+#define BSD_NBITS(x) ((x) & 0x1F)
+
+#define BSD_CURRENT_VERSION 1
+
/*
* A dictionary for doing BSD compress.
*/
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 maxbits;
+ u_char debug;
u_char unit;
u_short mru;
+ u_short seqno; /* sequence number of next packet */
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 */
+ u_int in_count; /* uncompressed bytes */
+ u_int bytes_out; /* compressed bytes */
+ u_int ratio; /* recent compression ratio */
+ u_int 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;
+ u_int32_t fcode;
struct {
#ifdef BSD_LITTLE_ENDIAN
u_short prefix; /* preceding code */
} dict[1];
};
-#define BSD_OVHD 3 /* BSD compress overhead/packet */
+#define BSD_OVHD 2 /* BSD compress overhead/packet */
#define MIN_BSD_BITS 9
#define BSD_INIT_BITS MIN_BSD_BITS
#define MAX_BSD_BITS 15
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 int bsd_decompress __P((void *state, mblk_t *cmp, mblk_t **dmpp));
static void bsd_reset __P((void *state));
/*
#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 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)
+
+#define DECOMP_CHUNK 256
/*
* clear the dictionary
bsd_check(db)
struct bsd_db *db;
{
- u_long new_ratio;
+ u_int 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) {
+ 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;
}
* by incompressible data.
*
* This does not overflow, because
- * db->in_count <= 0x7fffff.
+ * db->in_count <= RATIO_MAX.
*/
- new_ratio = db->in_count<<8;
+ 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 < 256) {
+ if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE) {
bsd_clear(db);
return 1;
}
u_int newlen, hsize, hshift, maxmaxcode;
struct bsd_db *db;
- if (opt_len != 3 || options[0] != 0x21 || options[1] != 3)
+ if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
+ || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
return NULL;
- bits = options[2];
+ bits = BSD_NBITS(options[2]);
switch (bits) {
case 9: /* needs 82152 for both directions */
case 10: /* needs 84144 */
db->hsize = hsize;
db->hshift = hshift;
db->maxmaxcode = maxmaxcode;
+ db->maxbits = bits;
return (void *) db;
}
int i;
if (opt_len != 3 || options[0] != 0x21 || options[1] != 3
- || MAXCODE(options[2]) != db->maxmaxcode
+ || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION
+ || BSD_NBITS(options[2]) != db->maxbits
|| decomp && db->lens == NULL)
return 0;
/*
* 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)
+bsd_compress(state, mretp, mp, slen, maxolen)
void *state;
- mblk_t **mret; /* return compressed mbuf chain here */
+ mblk_t **mretp; /* return compressed mbuf chain here */
mblk_t *mp; /* from here */
int slen; /* uncompressed length */
int maxolen; /* max compressed length */
u_int max_ent = db->max_ent;
u_int n_bits = db->n_bits;
u_int bitno = 32;
- u_long accm = 0;
+ u_int32_t accm = 0, fcode;
struct bsd_dict *dictp;
- u_long fcode;
u_char c;
- long hval, disp, ent;
- mblk_t *np;
+ int hval, disp, ent;
+ mblk_t *np, *mret;
u_char *rptr, *wptr;
u_char *cp_end;
int olen;
mblk_t *m, **mnp;
- int proto;
#define PUTBYTE(v) { \
if (wptr) { \
} while (bitno <= 24); \
}
+ /*
+ * First get the protocol and check that we're
+ * interested in this packet.
+ */
+ *mretp = NULL;
+ rptr = mp->b_rptr;
+ if (rptr + PPP_HDRLEN > mp->b_wptr) {
+ if (!pullupmsg(mp, PPP_HDRLEN))
+ return 0;
+ rptr = mp->b_rptr;
+ }
+ ent = PPP_PROTOCOL(rptr); /* get the protocol */
+ if (ent < 0x21 || ent > 0xf9)
+ return 0;
+
/* 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;
+ 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;
+ if (mret != NULL) {
+ freemsg(mret);
+ mnp = &mret;
}
break;
}
}
*mnp = NULL;
- rptr = mp->b_rptr;
- if ((m = *mret) != NULL) {
+ if ((m = mret) != NULL) {
wptr = m->b_wptr;
cp_end = m->b_datap->db_lim;
} else
/*
* Copy the PPP header over, changing the protocol,
- * and install the 3-byte sequence number.
+ * and install the 2-byte sequence number.
*/
- slen += db->seqno - PPP_HDRLEN + 1;
- db->seqno = slen;
if (wptr) {
- wptr[0] = rptr[0]; /* assumes the ppp header is */
- wptr[1] = rptr[1]; /* all in one mblk */
+ wptr[0] = PPP_ADDRESS(rptr);
+ wptr[1] = PPP_CONTROL(rptr);
wptr[2] = 0; /* change the protocol */
wptr[3] = PPP_COMP;
- wptr[4] = slen>>16;
- wptr[5] = slen>>8;
- wptr[6] = slen;
+ wptr[4] = db->seqno >> 8;
+ wptr[5] = db->seqno;
wptr += PPP_HDRLEN + BSD_OVHD;
}
-
- /* start with the protocol byte */
- ent = rptr[3];
+ ++db->seqno;
rptr += PPP_HDRLEN;
+
slen = mp->b_wptr - rptr;
db->in_count += slen + 1;
np = mp->b_cont;
if (bsd_check(db))
OUTPUT(CLEAR); /* do not count the CLEAR */
- /* Pad dribble bits of last code with ones.
+ /*
+ * 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
+ /*
+ * 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) {
+ if (olen + PPP_HDRLEN + BSD_OVHD > maxolen && mret != NULL) {
/* throw away the compressed stuff if it is longer than uncompressed */
- freemsg(*mret);
- *mret = NULL;
+ freemsg(mret);
+ mret = NULL;
} else if (wptr != NULL) {
m->b_wptr = wptr;
if (m->b_cont) {
}
}
+ *mretp = mret;
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)
u_int max_ent = db->max_ent;
u_int n_bits = db->n_bits;
struct bsd_dict *dictp;
- u_long fcode;
+ u_int32_t fcode;
u_char c;
long hval, disp;
int slen;
u_char *rptr;
u_int ent;
- db->incomp_count++;
+ rptr = dmsg->b_rptr;
+ if (rptr + PPP_HDRLEN > dmsg->b_wptr) {
+ if (!pullupmsg(dmsg, PPP_HDRLEN))
+ return;
+ rptr = dmsg->b_rptr;
+ }
+ ent = PPP_PROTOCOL(rptr); /* get the protocol */
+ if (ent < 0x21 || ent > 0xf9)
+ return;
+ 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;
continue; /* skip zero-length buffers */
}
db->in_count += slen;
- db->seqno += slen;
do {
c = *rptr++;
/*
* Decompress "BSD Compress"
*/
-static mblk_t * /* 0=failed, so zap CCP */
-bsd_decompress(state, cmsg, hdroff)
+static int
+bsd_decompress(state, cmsg, dmpp)
void *state;
- mblk_t *cmsg;
- int hdroff;
+ mblk_t *cmsg, **dmpp;
{
struct bsd_db *db = (struct bsd_db *) state;
u_int max_ent = db->max_ent;
- u_long accm = 0;
+ 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 */
int explen, i, seq, len;
u_int incode, oldcode, finchar;
u_char *p, *rptr, *wptr;
- mblk_t *dmsg;
+ mblk_t *dmsg, *mret;
int adrs, ctrl;
- int dlen, space, codelen;
+ int dlen, space, codelen, extra;
/*
* 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 (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;
+ return DECOMP_ERROR;
}
rptr = cmsg->b_rptr;
}
adrs = PPP_ADDRESS(rptr);
ctrl = PPP_CONTROL(rptr);
rptr += PPP_HDRLEN;
- seq = (rptr[0] << 16) + (rptr[1] << 8) + rptr[2];
- rptr += 3;
+ seq = (rptr[0] << 8) + rptr[1];
+ rptr += BSD_OVHD;
len = cmsg->b_wptr - rptr;
/*
- * Check the sequence number and give up if the length is nonsense.
- * The check is against mru+1 because we compress one byte of protocol.
+ * Check the sequence number and give up if it is not what we expect.
*/
- explen = (seq - db->seqno) & 0xffffff;
- db->seqno = seq;
- if (explen > db->mru + 1 || explen < 1) {
+ if (seq != db->seqno++) {
if (db->debug)
- printf("bsd_decomp%d: bad length 0x%x\n", db->unit, explen);
- return 0;
+ printf("bsd_decomp%d: bad sequence # %d, expected %d\n",
+ db->unit, seq, db->seqno - 1);
+ return DECOMP_ERROR;
}
- /* 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;
+ /*
+ * Allocate one message block to start with.
+ */
+ if ((dmsg = allocb(DECOMP_CHUNK, BPRI_MED)) == NULL)
+ return DECOMP_ERROR;
+ mret = dmsg;
+ dmsg->b_rptr = wptr = dmsg->b_wptr;
/* Fill in the ppp header, but not the last byte of the protocol
(that comes from the decompressed data). */
space = dmsg->b_datap->db_lim - wptr;
db->bytes_out += len;
- dlen = explen;
oldcode = CLEAR;
+ explen = 0;
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;
- }
+ if (!cmsg) /* quit at end of message */
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.
+ /*
+ * 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 += n_bits;
if (incode == CLEAR) {
- /* The dictionary must only be cleared at
+ /*
+ * The dictionary must only be cleared at
* the end of a packet. But there could be an
* empty message block at the end.
*/
freemsg(dmsg);
if (db->debug)
printf("bsd_decomp%d: bad CLEAR\n", db->unit);
- return 0;
+ return DECOMP_FATALERROR;
}
}
bsd_clear(db);
break;
}
+ if (incode > max_ent+2 || incode > db->maxmaxcode
+ || incode > max_ent && 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 DECOMP_FATALERROR;
+ }
+
/* 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
+ extra = 1;
+ } else {
finchar = incode;
+ extra = 0;
+ }
codelen = db->lens[finchar];
- dlen -= codelen;
- if (dlen < 0) {
+ explen += codelen + extra;
+ if (explen > db->mru + 1) {
freemsg(dmsg);
if (db->debug)
- printf("bsd_decomp%d: ran out of buffer\n", db->unit);
- return 0;
+ printf("bsd_decomp%d: ran out of mru\n", db->unit);
+ return DECOMP_FATALERROR;
}
- /* decode code and install in decompressed buffer */
- space -= codelen;
+ /*
+ * Decode this code and install it in the decompressed buffer.
+ */
+ space -= codelen + extra;
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;
+ /* Allocate another message block. */
+ dmsg->b_wptr = wptr;
+ dlen = codelen + extra;
+ if (dlen < DECOMP_CHUNK)
+ dlen = DECOMP_CHUNK;
+ if ((dmsg->b_cont = allocb(dlen, BPRI_MED)) == NULL) {
+ freemsg(dmsg);
+ return DECOMP_ERROR;
+ }
+ dmsg = dmsg->b_cont;
+ wptr = dmsg->b_wptr;
+ space = dmsg->b_datap->db_lim - wptr - codelen - extra;
}
p = (wptr += codelen);
while (finchar > LAST) {
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;
+ return DECOMP_FATALERROR;
}
if (dictp->codem1 != finchar-1) {
freemsg(dmsg);
db->unit, incode, finchar);
printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode,
db->dict[finchar].cptr, dictp->codem1);
- return 0;
+ return DECOMP_FATALERROR;
}
#endif
*--p = dictp->f.hs.suffix;
db->unit, codelen, incode, max_ent);
#endif
- if (incode > max_ent) { /* the KwKwK case again */
+ if (extra) /* the KwKwK case again */
*wptr++ = finchar;
- --space;
- }
/*
* If not first code in a packet, and
*/
if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
struct bsd_dict *dictp2;
- u_long fcode;
- long hval, disp;
+ u_int32_t fcode;
+ int hval, disp;
fcode = BSD_KEY(oldcode,finchar);
hval = BSD_HASH(oldcode,finchar,db->hshift);
} while (dictp->codem1 < max_ent);
}
- /* Invalidate previous hash table entry
+ /*
+ * Invalidate previous hash table entry
* assigned this code, and then take it over
*/
dictp2 = &db->dict[max_ent+1];
}
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
+ /*
+ * Keep the checkpoint right so that incompressible packets
* clear the dictionary at the right times.
*/
db->in_count += explen;
db->unit);
}
- return dmsg;
+ *dmpp = mret;
+ return DECOMP_OK;
}
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