/*
|
* Update: The Berkeley copyright was changed, and the change
|
* is retroactive to all "true" BSD software (ie everything
|
* from UCB as opposed to other peoples code that just carried
|
* the same license). The new copyright doesn't clash with the
|
* GPL, so the module-only restriction has been removed..
|
*/
|
|
/* 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 contiguous buffers on Linux-derived systems.
|
*
|
* ==FILEVERSION 20000226==
|
*
|
* NOTE TO MAINTAINERS:
|
* If you modify this file at all, please set the number above to the
|
* date of the modification as YYMMDD (year month day).
|
* bsd_comp.c is shipped with a PPP distribution as well as with
|
* the kernel; if everyone increases the FILEVERSION number above,
|
* then scripts can do the right thing when deciding whether to
|
* install a new bsd_comp.c file. Don't change the format of that
|
* line otherwise, so the installation script can recognize it.
|
*
|
* From: bsd_comp.c,v 1.3 1994/12/08 01:59:58 paulus Exp
|
*/
|
|
#include <linux/module.h>
|
#include <linux/init.h>
|
#include <linux/slab.h>
|
#include <linux/vmalloc.h>
|
#include <linux/string.h>
|
|
#include <linux/ppp_defs.h>
|
|
#undef PACKETPTR
|
#define PACKETPTR 1
|
#include <linux/ppp-comp.h>
|
#undef PACKETPTR
|
|
#include <asm/byteorder.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.
|
*/
|
|
/*
|
* 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.
|
*/
|
|
struct bsd_dict {
|
union { /* hash value */
|
unsigned long fcode;
|
struct {
|
#if defined(__LITTLE_ENDIAN) /* Little endian order */
|
unsigned short prefix; /* preceding code */
|
unsigned char suffix; /* last character of new code */
|
unsigned char pad;
|
#elif defined(__BIG_ENDIAN) /* Big endian order */
|
unsigned char pad;
|
unsigned char suffix; /* last character of new code */
|
unsigned short prefix; /* preceding code */
|
#else
|
#error Endianness not defined...
|
#endif
|
} hs;
|
} f;
|
unsigned short codem1; /* output of hash table -1 */
|
unsigned short cptr; /* map code to hash table entry */
|
};
|
|
struct bsd_db {
|
int totlen; /* length of this structure */
|
unsigned int hsize; /* size of the hash table */
|
unsigned char hshift; /* used in hash function */
|
unsigned char n_bits; /* current bits/code */
|
unsigned char maxbits; /* maximum bits/code */
|
unsigned char debug; /* non-zero if debug desired */
|
unsigned char unit; /* ppp unit number */
|
unsigned short seqno; /* sequence # of next packet */
|
unsigned int mru; /* size of receive (decompress) bufr */
|
unsigned int maxmaxcode; /* largest valid code */
|
unsigned int max_ent; /* largest code in use */
|
unsigned int in_count; /* uncompressed bytes, aged */
|
unsigned int bytes_out; /* compressed bytes, aged */
|
unsigned int ratio; /* recent compression ratio */
|
unsigned int checkpoint; /* when to next check the ratio */
|
unsigned int clear_count; /* times dictionary cleared */
|
unsigned int incomp_count; /* incompressible packets */
|
unsigned int incomp_bytes; /* incompressible bytes */
|
unsigned int uncomp_count; /* uncompressed packets */
|
unsigned int uncomp_bytes; /* uncompressed bytes */
|
unsigned int comp_count; /* compressed packets */
|
unsigned int comp_bytes; /* compressed bytes */
|
unsigned short *lens; /* array of lengths of codes */
|
struct bsd_dict *dict; /* dictionary */
|
};
|
|
#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 void bsd_free (void *state);
|
static void *bsd_alloc(unsigned char *options, int opt_len, int decomp);
|
static void *bsd_comp_alloc (unsigned char *options, int opt_len);
|
static void *bsd_decomp_alloc (unsigned char *options, int opt_len);
|
|
static int bsd_init (void *db, unsigned char *options,
|
int opt_len, int unit, int debug, int decomp);
|
static int bsd_comp_init (void *state, unsigned char *options,
|
int opt_len, int unit, int opthdr, int debug);
|
static int bsd_decomp_init (void *state, unsigned char *options,
|
int opt_len, int unit, int opthdr, int mru,
|
int debug);
|
|
static void bsd_reset (void *state);
|
static void bsd_comp_stats (void *state, struct compstat *stats);
|
|
static int bsd_compress (void *state, unsigned char *rptr,
|
unsigned char *obuf, int isize, int osize);
|
static void bsd_incomp (void *state, unsigned char *ibuf, int icnt);
|
|
static int bsd_decompress (void *state, unsigned char *ibuf, int isize,
|
unsigned char *obuf, int osize);
|
|
/* These are in ppp_generic.c */
|
extern int ppp_register_compressor (struct compressor *cp);
|
extern void ppp_unregister_compressor (struct compressor *cp);
|
|
/*
|
* 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) ((((unsigned long)(suffix))<<(hshift)) \
|
^ (unsigned long)(prefix))
|
#define BSD_KEY(prefix,suffix) ((((unsigned long)(suffix)) << 16) \
|
+ (unsigned long)(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(struct bsd_db *db)
|
{
|
db->clear_count++;
|
db->max_ent = FIRST-1;
|
db->n_bits = BSD_INIT_BITS;
|
db->bytes_out = 0;
|
db->in_count = 0;
|
db->ratio = 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 bsd_check (struct bsd_db *db) /* 1=output CLEAR */
|
{
|
unsigned 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 >> 2);
|
db->bytes_out -= (db->bytes_out >> 2);
|
}
|
|
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 (void *state, struct compstat *stats)
|
{
|
struct bsd_db *db = (struct bsd_db *) state;
|
|
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->in_count = db->in_count;
|
stats->bytes_out = db->bytes_out;
|
}
|
|
/*
|
* Reset state, as on a CCP ResetReq.
|
*/
|
|
static void bsd_reset (void *state)
|
{
|
struct bsd_db *db = (struct bsd_db *) state;
|
|
bsd_clear(db);
|
|
db->seqno = 0;
|
db->clear_count = 0;
|
}
|
|
/*
|
* Release the compression structure
|
*/
|
|
static void bsd_free (void *state)
|
{
|
struct bsd_db *db = state;
|
|
if (!db)
|
return;
|
|
/*
|
* Release the dictionary
|
*/
|
vfree(db->dict);
|
db->dict = NULL;
|
/*
|
* Release the string buffer
|
*/
|
vfree(db->lens);
|
db->lens = NULL;
|
/*
|
* Finally release the structure itself.
|
*/
|
kfree(db);
|
}
|
|
/*
|
* Allocate space for a (de) compressor.
|
*/
|
|
static void *bsd_alloc (unsigned char *options, int opt_len, int decomp)
|
{
|
int bits;
|
unsigned int hsize, hshift, maxmaxcode;
|
struct bsd_db *db;
|
|
if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
|
|| 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;
|
}
|
/*
|
* Allocate the main control structure for this instance.
|
*/
|
maxmaxcode = MAXCODE(bits);
|
db = kzalloc(sizeof (struct bsd_db),
|
GFP_KERNEL);
|
if (!db)
|
{
|
return NULL;
|
}
|
|
/*
|
* Allocate space for the dictionary. This may be more than one page in
|
* length.
|
*/
|
db->dict = vmalloc(array_size(hsize, sizeof(struct bsd_dict)));
|
if (!db->dict)
|
{
|
bsd_free (db);
|
return NULL;
|
}
|
|
/*
|
* If this is the compression buffer then there is no length data.
|
*/
|
if (!decomp)
|
{
|
db->lens = NULL;
|
}
|
/*
|
* For decompression, the length information is needed as well.
|
*/
|
else
|
{
|
db->lens = vmalloc(array_size(sizeof(db->lens[0]), (maxmaxcode + 1)));
|
if (!db->lens)
|
{
|
bsd_free (db);
|
return NULL;
|
}
|
}
|
/*
|
* Initialize the data information for the compression code
|
*/
|
db->totlen = sizeof (struct bsd_db) +
|
(sizeof (struct bsd_dict) * hsize);
|
|
db->hsize = hsize;
|
db->hshift = hshift;
|
db->maxmaxcode = maxmaxcode;
|
db->maxbits = bits;
|
|
return (void *) db;
|
}
|
|
static void *bsd_comp_alloc (unsigned char *options, int opt_len)
|
{
|
return bsd_alloc (options, opt_len, 0);
|
}
|
|
static void *bsd_decomp_alloc (unsigned char *options, int opt_len)
|
{
|
return bsd_alloc (options, opt_len, 1);
|
}
|
|
/*
|
* Initialize the database.
|
*/
|
|
static int bsd_init (void *state, unsigned char *options,
|
int opt_len, int unit, int debug, int decomp)
|
{
|
struct bsd_db *db = state;
|
int indx;
|
|
if ((opt_len != 3) || (options[0] != CI_BSD_COMPRESS) || (options[1] != 3)
|
|| (BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
|
|| (BSD_NBITS(options[2]) != db->maxbits)
|
|| (decomp && db->lens == NULL))
|
{
|
return 0;
|
}
|
|
if (decomp)
|
{
|
indx = LAST;
|
do
|
{
|
db->lens[indx] = 1;
|
}
|
while (indx-- > 0);
|
}
|
|
indx = db->hsize;
|
while (indx-- != 0)
|
{
|
db->dict[indx].codem1 = BADCODEM1;
|
db->dict[indx].cptr = 0;
|
}
|
|
db->unit = unit;
|
db->mru = 0;
|
#ifndef DEBUG
|
if (debug)
|
#endif
|
db->debug = 1;
|
|
bsd_reset(db);
|
|
return 1;
|
}
|
|
static int bsd_comp_init (void *state, unsigned char *options,
|
int opt_len, int unit, int opthdr, int debug)
|
{
|
return bsd_init (state, options, opt_len, unit, debug, 0);
|
}
|
|
static int bsd_decomp_init (void *state, unsigned char *options,
|
int opt_len, int unit, int opthdr, int mru,
|
int debug)
|
{
|
return bsd_init (state, options, opt_len, unit, debug, 1);
|
}
|
|
/*
|
* Obtain pointers to the various structures in the compression tables
|
*/
|
|
#define dict_ptrx(p,idx) &(p->dict[idx])
|
#define lens_ptrx(p,idx) &(p->lens[idx])
|
|
#ifdef DEBUG
|
static unsigned short *lens_ptr(struct bsd_db *db, int idx)
|
{
|
if ((unsigned int) idx > (unsigned int) db->maxmaxcode)
|
{
|
printk ("<9>ppp: lens_ptr(%d) > max\n", idx);
|
idx = 0;
|
}
|
return lens_ptrx (db, idx);
|
}
|
|
static struct bsd_dict *dict_ptr(struct bsd_db *db, int idx)
|
{
|
if ((unsigned int) idx >= (unsigned int) db->hsize)
|
{
|
printk ("<9>ppp: dict_ptr(%d) > max\n", idx);
|
idx = 0;
|
}
|
return dict_ptrx (db, idx);
|
}
|
|
#else
|
#define lens_ptr(db,idx) lens_ptrx(db,idx)
|
#define dict_ptr(db,idx) dict_ptrx(db,idx)
|
#endif
|
|
/*
|
* compress a packet
|
*
|
* The result of this function is the size of the compressed
|
* packet. A zero is returned if the packet was not compressed
|
* for some reason, such as the size being larger than uncompressed.
|
*
|
* One change from the BSD compress command is that when the
|
* code size expands, we do not output a bunch of padding.
|
*/
|
|
static int bsd_compress (void *state, unsigned char *rptr, unsigned char *obuf,
|
int isize, int osize)
|
{
|
struct bsd_db *db;
|
int hshift;
|
unsigned int max_ent;
|
unsigned int n_bits;
|
unsigned int bitno;
|
unsigned long accm;
|
int ent;
|
unsigned long fcode;
|
struct bsd_dict *dictp;
|
unsigned char c;
|
int hval;
|
int disp;
|
int ilen;
|
int mxcode;
|
unsigned char *wptr;
|
int olen;
|
|
#define PUTBYTE(v) \
|
{ \
|
++olen; \
|
if (wptr) \
|
{ \
|
*wptr++ = (unsigned char) (v); \
|
if (olen >= osize) \
|
{ \
|
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.
|
*/
|
|
ent = PPP_PROTOCOL(rptr);
|
if (ent < 0x21 || ent > 0xf9)
|
{
|
return 0;
|
}
|
|
db = (struct bsd_db *) state;
|
hshift = db->hshift;
|
max_ent = db->max_ent;
|
n_bits = db->n_bits;
|
bitno = 32;
|
accm = 0;
|
mxcode = MAXCODE (n_bits);
|
|
/* Initialize the output pointers */
|
wptr = obuf;
|
olen = PPP_HDRLEN + BSD_OVHD;
|
|
if (osize > isize)
|
{
|
osize = isize;
|
}
|
|
/* This is the PPP header information */
|
if (wptr)
|
{
|
*wptr++ = PPP_ADDRESS(rptr);
|
*wptr++ = PPP_CONTROL(rptr);
|
*wptr++ = 0;
|
*wptr++ = PPP_COMP;
|
*wptr++ = db->seqno >> 8;
|
*wptr++ = db->seqno;
|
}
|
|
/* Skip the input header */
|
rptr += PPP_HDRLEN;
|
isize -= PPP_HDRLEN;
|
ilen = ++isize; /* Low byte of protocol is counted as input */
|
|
while (--ilen > 0)
|
{
|
c = *rptr++;
|
fcode = BSD_KEY (ent, c);
|
hval = BSD_HASH (ent, c, hshift);
|
dictp = dict_ptr (db, 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 = dict_ptr (db, 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;
|
struct bsd_dict *dictp3;
|
int indx;
|
|
/* expand code size if needed */
|
if (max_ent >= mxcode)
|
{
|
db->n_bits = ++n_bits;
|
mxcode = MAXCODE (n_bits);
|
}
|
|
/* Invalidate old hash table entry using
|
* this code, and then take it over.
|
*/
|
|
dictp2 = dict_ptr (db, max_ent + 1);
|
indx = dictp2->cptr;
|
dictp3 = dict_ptr (db, indx);
|
|
if (dictp3->codem1 == max_ent)
|
{
|
dictp3->codem1 = BADCODEM1;
|
}
|
|
dictp2->cptr = hval;
|
dictp->codem1 = max_ent;
|
dictp->f.fcode = fcode;
|
db->max_ent = ++max_ent;
|
|
if (db->lens)
|
{
|
unsigned short *len1 = lens_ptr (db, max_ent);
|
unsigned short *len2 = lens_ptr (db, ent);
|
*len1 = *len2 + 1;
|
}
|
}
|
ent = c;
|
}
|
|
OUTPUT(ent); /* output the last code */
|
|
db->bytes_out += olen - PPP_HDRLEN - BSD_OVHD;
|
db->uncomp_bytes += isize;
|
db->in_count += isize;
|
++db->uncomp_count;
|
++db->seqno;
|
|
if (bitno < 32)
|
{
|
++db->bytes_out; /* must be set before calling bsd_check */
|
}
|
|
/*
|
* Generate the clear command if needed
|
*/
|
|
if (bsd_check(db))
|
{
|
OUTPUT (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 because the decompressor will do so.
|
*/
|
|
if (max_ent >= mxcode && max_ent < db->maxmaxcode)
|
{
|
db->n_bits++;
|
}
|
|
/* If output length is too large then this is an incomplete frame. */
|
if (wptr == NULL)
|
{
|
++db->incomp_count;
|
db->incomp_bytes += isize;
|
olen = 0;
|
}
|
else /* Count the number of compressed frames */
|
{
|
++db->comp_count;
|
db->comp_bytes += olen;
|
}
|
|
/* Return the resulting output length */
|
return olen;
|
#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 (void *state, unsigned char *ibuf, int icnt)
|
{
|
(void) bsd_compress (state, ibuf, (char *) 0, icnt, 0);
|
}
|
|
/*
|
* 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.
|
*/
|
|
static int bsd_decompress (void *state, unsigned char *ibuf, int isize,
|
unsigned char *obuf, int osize)
|
{
|
struct bsd_db *db;
|
unsigned int max_ent;
|
unsigned long accm;
|
unsigned int bitno; /* 1st valid bit in accm */
|
unsigned int n_bits;
|
unsigned int tgtbitno; /* bitno when we have a code */
|
struct bsd_dict *dictp;
|
int explen;
|
int seq;
|
unsigned int incode;
|
unsigned int oldcode;
|
unsigned int finchar;
|
unsigned char *p;
|
unsigned char *wptr;
|
int adrs;
|
int ctrl;
|
int ilen;
|
int codelen;
|
int extra;
|
|
db = (struct bsd_db *) state;
|
max_ent = db->max_ent;
|
accm = 0;
|
bitno = 32; /* 1st valid bit in accm */
|
n_bits = db->n_bits;
|
tgtbitno = 32 - n_bits; /* bitno when we have a code */
|
|
/*
|
* Save the address/control from the PPP header
|
* and then get the sequence number.
|
*/
|
|
adrs = PPP_ADDRESS (ibuf);
|
ctrl = PPP_CONTROL (ibuf);
|
|
seq = (ibuf[4] << 8) + ibuf[5];
|
|
ibuf += (PPP_HDRLEN + 2);
|
ilen = isize - (PPP_HDRLEN + 2);
|
|
/*
|
* Check the sequence number and give up if it differs from
|
* the value we're expecting.
|
*/
|
|
if (seq != db->seqno)
|
{
|
if (db->debug)
|
{
|
printk("bsd_decomp%d: bad sequence # %d, expected %d\n",
|
db->unit, seq, db->seqno - 1);
|
}
|
return DECOMP_ERROR;
|
}
|
|
++db->seqno;
|
db->bytes_out += ilen;
|
|
/*
|
* Fill in the ppp header, but not the last byte of the protocol
|
* (that comes from the decompressed data).
|
*/
|
|
wptr = obuf;
|
*wptr++ = adrs;
|
*wptr++ = ctrl;
|
*wptr++ = 0;
|
|
oldcode = CLEAR;
|
explen = 3;
|
|
/*
|
* Keep the checkpoint correctly so that incompressible packets
|
* clear the dictionary at the proper times.
|
*/
|
|
for (;;)
|
{
|
if (ilen-- <= 0)
|
{
|
db->in_count += (explen - 3); /* don't count the header */
|
break;
|
}
|
|
/*
|
* 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 |= *ibuf++ << bitno;
|
if (tgtbitno < bitno)
|
{
|
continue;
|
}
|
|
incode = accm >> tgtbitno;
|
accm <<= n_bits;
|
bitno += n_bits;
|
|
/*
|
* The dictionary must only be cleared at the end of a packet.
|
*/
|
|
if (incode == CLEAR)
|
{
|
if (ilen > 0)
|
{
|
if (db->debug)
|
{
|
printk("bsd_decomp%d: bad CLEAR\n", db->unit);
|
}
|
return DECOMP_FATALERROR; /* probably a bug */
|
}
|
|
bsd_clear(db);
|
break;
|
}
|
|
if ((incode > max_ent + 2) || (incode > db->maxmaxcode)
|
|| (incode > max_ent && oldcode == CLEAR))
|
{
|
if (db->debug)
|
{
|
printk("bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
|
db->unit, incode, oldcode);
|
printk("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 = *(lens_ptr (db, finchar));
|
explen += codelen + extra;
|
if (explen > osize)
|
{
|
if (db->debug)
|
{
|
printk("bsd_decomp%d: ran out of mru\n", db->unit);
|
#ifdef DEBUG
|
printk(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n",
|
ilen, finchar, codelen, explen);
|
#endif
|
}
|
return DECOMP_FATALERROR;
|
}
|
|
/*
|
* Decode this code and install it in the decompressed buffer.
|
*/
|
|
wptr += codelen;
|
p = wptr;
|
while (finchar > LAST)
|
{
|
struct bsd_dict *dictp2 = dict_ptr (db, finchar);
|
|
dictp = dict_ptr (db, dictp2->cptr);
|
#ifdef DEBUG
|
if (--codelen <= 0 || dictp->codem1 != finchar-1)
|
{
|
if (codelen <= 0)
|
{
|
printk("bsd_decomp%d: fell off end of chain ", db->unit);
|
printk("0x%x at 0x%x by 0x%x, max_ent=0x%x\n",
|
incode, finchar, dictp2->cptr, max_ent);
|
}
|
else
|
{
|
if (dictp->codem1 != finchar-1)
|
{
|
printk("bsd_decomp%d: bad code chain 0x%x "
|
"finchar=0x%x ",
|
db->unit, incode, finchar);
|
|
printk("oldcode=0x%x cptr=0x%x codem1=0x%x\n",
|
oldcode, dictp2->cptr, dictp->codem1);
|
}
|
}
|
return DECOMP_FATALERROR;
|
}
|
#endif
|
*--p = dictp->f.hs.suffix;
|
finchar = dictp->f.hs.prefix;
|
}
|
*--p = finchar;
|
|
#ifdef DEBUG
|
if (--codelen != 0)
|
{
|
printk("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, *dictp3;
|
unsigned short *lens1, *lens2;
|
unsigned long fcode;
|
int hval, disp, indx;
|
|
fcode = BSD_KEY(oldcode,finchar);
|
hval = BSD_HASH(oldcode,finchar,db->hshift);
|
dictp = dict_ptr (db, 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 = dict_ptr (db, hval);
|
}
|
while (dictp->codem1 < max_ent);
|
}
|
|
/*
|
* Invalidate previous hash table entry
|
* assigned this code, and then take it over
|
*/
|
|
dictp2 = dict_ptr (db, max_ent + 1);
|
indx = dictp2->cptr;
|
dictp3 = dict_ptr (db, indx);
|
|
if (dictp3->codem1 == max_ent)
|
{
|
dictp3->codem1 = BADCODEM1;
|
}
|
|
dictp2->cptr = hval;
|
dictp->codem1 = max_ent;
|
dictp->f.fcode = fcode;
|
db->max_ent = ++max_ent;
|
|
/* Update the length of this string. */
|
lens1 = lens_ptr (db, max_ent);
|
lens2 = lens_ptr (db, oldcode);
|
*lens1 = *lens2 + 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;
|
}
|
|
++db->comp_count;
|
++db->uncomp_count;
|
db->comp_bytes += isize - BSD_OVHD - PPP_HDRLEN;
|
db->uncomp_bytes += explen;
|
|
if (bsd_check(db))
|
{
|
if (db->debug)
|
{
|
printk("bsd_decomp%d: peer should have cleared dictionary on %d\n",
|
db->unit, db->seqno - 1);
|
}
|
}
|
return explen;
|
}
|
|
/*************************************************************
|
* Table of addresses for the BSD compression module
|
*************************************************************/
|
|
static struct compressor ppp_bsd_compress = {
|
.compress_proto = CI_BSD_COMPRESS,
|
.comp_alloc = bsd_comp_alloc,
|
.comp_free = bsd_free,
|
.comp_init = bsd_comp_init,
|
.comp_reset = bsd_reset,
|
.compress = bsd_compress,
|
.comp_stat = bsd_comp_stats,
|
.decomp_alloc = bsd_decomp_alloc,
|
.decomp_free = bsd_free,
|
.decomp_init = bsd_decomp_init,
|
.decomp_reset = bsd_reset,
|
.decompress = bsd_decompress,
|
.incomp = bsd_incomp,
|
.decomp_stat = bsd_comp_stats,
|
.owner = THIS_MODULE
|
};
|
|
/*************************************************************
|
* Module support routines
|
*************************************************************/
|
|
static int __init bsdcomp_init(void)
|
{
|
int answer = ppp_register_compressor(&ppp_bsd_compress);
|
if (answer == 0)
|
printk(KERN_INFO "PPP BSD Compression module registered\n");
|
return answer;
|
}
|
|
static void __exit bsdcomp_cleanup(void)
|
{
|
ppp_unregister_compressor(&ppp_bsd_compress);
|
}
|
|
module_init(bsdcomp_init);
|
module_exit(bsdcomp_cleanup);
|
MODULE_LICENSE("Dual BSD/GPL");
|
MODULE_ALIAS("ppp-compress-" __stringify(CI_BSD_COMPRESS));
|
