+++ /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 contiguous buffers on Linux-derived systems.
- *
- * ==FILEVERSION 970607==
- *
- * 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
- */
-
-#ifndef MODULE
-#error This file must be compiled as a module.
-#endif
-
-#include <linux/version.h>
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/sched.h>
-#include <linux/types.h>
-#include <linux/fcntl.h>
-#include <linux/interrupt.h>
-#include <linux/ptrace.h>
-#include <linux/malloc.h>
-#include <linux/ioport.h>
-#include <linux/in.h>
-
-#undef VERSION
-/* a nice define to generate linux version numbers */
-#define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
-
-#if LINUX_VERSION_CODE >= VERSION(2,1,4)
-#include <linux/vmalloc.h>
-#endif
-
-#include <linux/tty.h>
-#include <linux/errno.h>
-#include <linux/sched.h> /* to get the struct task_struct */
-#include <linux/string.h> /* used in new tty drivers */
-#include <linux/signal.h> /* used in new tty drivers */
-
-#include <asm/system.h>
-#include <asm/bitops.h>
-#include <asm/byteorder.h>
-
-#include <linux/if.h>
-
-#include <linux/if_ether.h>
-#include <linux/netdevice.h>
-#include <linux/skbuff.h>
-#include <linux/inet.h>
-#include <linux/ioctl.h>
-
-#include <linux/ppp_defs.h>
-
-#undef PACKETPTR
-#define PACKETPTR 1
-#include <linux/ppp-comp.h>
-#undef PACKETPTR
-
-/*
- * 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.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 = (struct bsd_db *) state;
-
- if (db)
- {
-/*
- * Release the dictionary
- */
- if (db->dict)
- {
- vfree (db->dict);
- db->dict = NULL;
- }
-/*
- * Release the string buffer
- */
- if (db->lens)
- {
- vfree (db->lens);
- db->lens = NULL;
- }
-/*
- * Finally release the structure itself.
- */
- kfree (db);
- MOD_DEC_USE_COUNT;
- }
- }
-
-/*
- * 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 = (struct bsd_db *) kmalloc (sizeof (struct bsd_db),
- GFP_KERNEL);
- if (!db)
- {
- return NULL;
- }
-
- memset (db, 0, sizeof(struct bsd_db));
-/*
- * Allocate space for the dictionary. This may be more than one page in
- * length.
- */
- db->dict = (struct bsd_dict *) vmalloc (hsize *
- sizeof (struct bsd_dict));
- if (!db->dict)
- {
- bsd_free (db);
- return NULL;
- }
-
- MOD_INC_USE_COUNT;
-/*
- * 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 = (unsigned short *) vmalloc ((maxmaxcode + 1) *
- sizeof (db->lens[0]));
- 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 = {
- 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 */
-};
-
-/*************************************************************
- * Module support routines
- *************************************************************/
-
-int
-init_module(void)
-{
- int answer = ppp_register_compressor (&ppp_bsd_compress);
- if (answer == 0)
- printk (KERN_INFO "PPP BSD Compression module registered\n");
- return answer;
-}
-
-void
-cleanup_module(void)
-{
- ppp_unregister_compressor (&ppp_bsd_compress);
-}
projects / ppp.git / blobdiff