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![Jesper Juhl](/assets/img/avatar_default.png)
The general kernel memory allocation functions return void pointers and there is no need to cast their return values. Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1170 lines
29 KiB
C
1170 lines
29 KiB
C
/*
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* Update: The Berkeley copyright was changed, and the change
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* is retroactive to all "true" BSD software (ie everything
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* from UCB as opposed to other peoples code that just carried
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* the same license). The new copyright doesn't clash with the
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* GPL, so the module-only restriction has been removed..
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*/
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/* Because this code is derived from the 4.3BSD compress source:
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*
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* Copyright (c) 1985, 1986 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* James A. Woods, derived from original work by Spencer Thomas
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* and Joseph Orost.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* This version is for use with contiguous buffers on Linux-derived systems.
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*
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* ==FILEVERSION 20000226==
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*
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* NOTE TO MAINTAINERS:
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* If you modify this file at all, please set the number above to the
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* date of the modification as YYMMDD (year month day).
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* bsd_comp.c is shipped with a PPP distribution as well as with
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* the kernel; if everyone increases the FILEVERSION number above,
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* then scripts can do the right thing when deciding whether to
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* install a new bsd_comp.c file. Don't change the format of that
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* line otherwise, so the installation script can recognize it.
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*
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* From: bsd_comp.c,v 1.3 1994/12/08 01:59:58 paulus Exp
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/string.h>
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#include <linux/ppp_defs.h>
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#undef PACKETPTR
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#define PACKETPTR 1
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#include <linux/ppp-comp.h>
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#undef PACKETPTR
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#include <asm/byteorder.h>
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/*
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* PPP "BSD compress" compression
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* The differences between this compression and the classic BSD LZW
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* source are obvious from the requirement that the classic code worked
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* with files while this handles arbitrarily long streams that
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* are broken into packets. They are:
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*
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* When the code size expands, a block of junk is not emitted by
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* the compressor and not expected by the decompressor.
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*
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* New codes are not necessarily assigned every time an old
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* code is output by the compressor. This is because a packet
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* end forces a code to be emitted, but does not imply that a
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* new sequence has been seen.
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*
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* The compression ratio is checked at the first end of a packet
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* after the appropriate gap. Besides simplifying and speeding
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* things up, this makes it more likely that the transmitter
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* and receiver will agree when the dictionary is cleared when
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* compression is not going well.
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*/
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/*
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* Macros to extract protocol version and number of bits
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* from the third byte of the BSD Compress CCP configuration option.
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*/
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#define BSD_VERSION(x) ((x) >> 5)
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#define BSD_NBITS(x) ((x) & 0x1F)
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#define BSD_CURRENT_VERSION 1
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/*
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* A dictionary for doing BSD compress.
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*/
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struct bsd_dict {
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union { /* hash value */
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unsigned long fcode;
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struct {
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#if defined(__LITTLE_ENDIAN) /* Little endian order */
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unsigned short prefix; /* preceding code */
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unsigned char suffix; /* last character of new code */
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unsigned char pad;
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#elif defined(__BIG_ENDIAN) /* Big endian order */
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unsigned char pad;
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unsigned char suffix; /* last character of new code */
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unsigned short prefix; /* preceding code */
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#else
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#error Endianness not defined...
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#endif
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} hs;
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} f;
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unsigned short codem1; /* output of hash table -1 */
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unsigned short cptr; /* map code to hash table entry */
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};
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struct bsd_db {
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int totlen; /* length of this structure */
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unsigned int hsize; /* size of the hash table */
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unsigned char hshift; /* used in hash function */
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unsigned char n_bits; /* current bits/code */
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unsigned char maxbits; /* maximum bits/code */
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unsigned char debug; /* non-zero if debug desired */
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unsigned char unit; /* ppp unit number */
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unsigned short seqno; /* sequence # of next packet */
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unsigned int mru; /* size of receive (decompress) bufr */
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unsigned int maxmaxcode; /* largest valid code */
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unsigned int max_ent; /* largest code in use */
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unsigned int in_count; /* uncompressed bytes, aged */
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unsigned int bytes_out; /* compressed bytes, aged */
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unsigned int ratio; /* recent compression ratio */
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unsigned int checkpoint; /* when to next check the ratio */
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unsigned int clear_count; /* times dictionary cleared */
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unsigned int incomp_count; /* incompressible packets */
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unsigned int incomp_bytes; /* incompressible bytes */
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unsigned int uncomp_count; /* uncompressed packets */
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unsigned int uncomp_bytes; /* uncompressed bytes */
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unsigned int comp_count; /* compressed packets */
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unsigned int comp_bytes; /* compressed bytes */
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unsigned short *lens; /* array of lengths of codes */
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struct bsd_dict *dict; /* dictionary */
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};
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#define BSD_OVHD 2 /* BSD compress overhead/packet */
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#define MIN_BSD_BITS 9
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#define BSD_INIT_BITS MIN_BSD_BITS
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#define MAX_BSD_BITS 15
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static void bsd_free (void *state);
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static void *bsd_alloc(unsigned char *options, int opt_len, int decomp);
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static void *bsd_comp_alloc (unsigned char *options, int opt_len);
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static void *bsd_decomp_alloc (unsigned char *options, int opt_len);
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static int bsd_init (void *db, unsigned char *options,
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int opt_len, int unit, int debug, int decomp);
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static int bsd_comp_init (void *state, unsigned char *options,
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int opt_len, int unit, int opthdr, int debug);
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static int bsd_decomp_init (void *state, unsigned char *options,
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int opt_len, int unit, int opthdr, int mru,
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int debug);
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static void bsd_reset (void *state);
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static void bsd_comp_stats (void *state, struct compstat *stats);
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static int bsd_compress (void *state, unsigned char *rptr,
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unsigned char *obuf, int isize, int osize);
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static void bsd_incomp (void *state, unsigned char *ibuf, int icnt);
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static int bsd_decompress (void *state, unsigned char *ibuf, int isize,
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unsigned char *obuf, int osize);
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/* These are in ppp_generic.c */
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extern int ppp_register_compressor (struct compressor *cp);
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extern void ppp_unregister_compressor (struct compressor *cp);
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/*
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* the next two codes should not be changed lightly, as they must not
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* lie within the contiguous general code space.
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*/
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#define CLEAR 256 /* table clear output code */
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#define FIRST 257 /* first free entry */
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#define LAST 255
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#define MAXCODE(b) ((1 << (b)) - 1)
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#define BADCODEM1 MAXCODE(MAX_BSD_BITS);
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#define BSD_HASH(prefix,suffix,hshift) ((((unsigned long)(suffix))<<(hshift)) \
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^ (unsigned long)(prefix))
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#define BSD_KEY(prefix,suffix) ((((unsigned long)(suffix)) << 16) \
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+ (unsigned long)(prefix))
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#define CHECK_GAP 10000 /* Ratio check interval */
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#define RATIO_SCALE_LOG 8
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#define RATIO_SCALE (1<<RATIO_SCALE_LOG)
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#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
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/*
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* clear the dictionary
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*/
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static void
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bsd_clear(struct bsd_db *db)
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{
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db->clear_count++;
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db->max_ent = FIRST-1;
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db->n_bits = BSD_INIT_BITS;
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db->bytes_out = 0;
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db->in_count = 0;
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db->ratio = 0;
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db->checkpoint = CHECK_GAP;
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}
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/*
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* If the dictionary is full, then see if it is time to reset it.
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*
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* Compute the compression ratio using fixed-point arithmetic
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* with 8 fractional bits.
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*
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* Since we have an infinite stream instead of a single file,
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* watch only the local compression ratio.
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*
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* Since both peers must reset the dictionary at the same time even in
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* the absence of CLEAR codes (while packets are incompressible), they
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* must compute the same ratio.
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*/
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static int bsd_check (struct bsd_db *db) /* 1=output CLEAR */
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{
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unsigned int new_ratio;
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if (db->in_count >= db->checkpoint)
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{
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/* age the ratio by limiting the size of the counts */
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if (db->in_count >= RATIO_MAX || db->bytes_out >= RATIO_MAX)
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{
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db->in_count -= (db->in_count >> 2);
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db->bytes_out -= (db->bytes_out >> 2);
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}
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db->checkpoint = db->in_count + CHECK_GAP;
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if (db->max_ent >= db->maxmaxcode)
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{
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/* Reset the dictionary only if the ratio is worse,
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* or if it looks as if it has been poisoned
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* by incompressible data.
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*
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* This does not overflow, because
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* db->in_count <= RATIO_MAX.
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*/
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new_ratio = db->in_count << RATIO_SCALE_LOG;
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if (db->bytes_out != 0)
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{
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new_ratio /= db->bytes_out;
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}
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if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE)
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{
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bsd_clear (db);
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return 1;
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}
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db->ratio = new_ratio;
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}
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}
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return 0;
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}
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/*
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* Return statistics.
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*/
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static void bsd_comp_stats (void *state, struct compstat *stats)
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{
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struct bsd_db *db = (struct bsd_db *) state;
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stats->unc_bytes = db->uncomp_bytes;
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stats->unc_packets = db->uncomp_count;
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stats->comp_bytes = db->comp_bytes;
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stats->comp_packets = db->comp_count;
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stats->inc_bytes = db->incomp_bytes;
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stats->inc_packets = db->incomp_count;
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stats->in_count = db->in_count;
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stats->bytes_out = db->bytes_out;
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}
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/*
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* Reset state, as on a CCP ResetReq.
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*/
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static void bsd_reset (void *state)
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{
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struct bsd_db *db = (struct bsd_db *) state;
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bsd_clear(db);
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db->seqno = 0;
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db->clear_count = 0;
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}
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/*
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* Release the compression structure
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*/
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static void bsd_free (void *state)
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{
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struct bsd_db *db = state;
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if (!db)
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return;
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/*
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* Release the dictionary
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*/
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vfree(db->dict);
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db->dict = NULL;
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/*
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* Release the string buffer
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*/
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vfree(db->lens);
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db->lens = NULL;
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/*
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* Finally release the structure itself.
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*/
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kfree(db);
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}
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/*
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* Allocate space for a (de) compressor.
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*/
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static void *bsd_alloc (unsigned char *options, int opt_len, int decomp)
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{
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int bits;
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unsigned int hsize, hshift, maxmaxcode;
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struct bsd_db *db;
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if (opt_len != 3 || options[0] != CI_BSD_COMPRESS || options[1] != 3
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|| BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
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{
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return NULL;
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}
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bits = BSD_NBITS(options[2]);
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switch (bits)
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{
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case 9: /* needs 82152 for both directions */
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case 10: /* needs 84144 */
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case 11: /* needs 88240 */
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case 12: /* needs 96432 */
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hsize = 5003;
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hshift = 4;
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break;
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case 13: /* needs 176784 */
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hsize = 9001;
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hshift = 5;
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break;
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case 14: /* needs 353744 */
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hsize = 18013;
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hshift = 6;
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break;
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case 15: /* needs 691440 */
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hsize = 35023;
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hshift = 7;
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break;
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case 16: /* needs 1366160--far too much, */
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/* hsize = 69001; */ /* and 69001 is too big for cptr */
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/* hshift = 8; */ /* in struct bsd_db */
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/* break; */
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default:
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return NULL;
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}
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/*
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* Allocate the main control structure for this instance.
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*/
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maxmaxcode = MAXCODE(bits);
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db = kzalloc(sizeof (struct bsd_db),
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GFP_KERNEL);
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if (!db)
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{
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return NULL;
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}
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/*
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* Allocate space for the dictionary. This may be more than one page in
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* length.
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*/
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db->dict = vmalloc(hsize * sizeof(struct bsd_dict));
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if (!db->dict)
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{
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bsd_free (db);
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return NULL;
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}
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/*
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* If this is the compression buffer then there is no length data.
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*/
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if (!decomp)
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{
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db->lens = NULL;
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}
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/*
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* For decompression, the length information is needed as well.
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*/
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else
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{
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db->lens = vmalloc((maxmaxcode + 1) * sizeof(db->lens[0]));
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if (!db->lens)
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{
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bsd_free (db);
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return (NULL);
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}
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}
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/*
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* Initialize the data information for the compression code
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*/
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db->totlen = sizeof (struct bsd_db) +
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(sizeof (struct bsd_dict) * hsize);
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db->hsize = hsize;
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db->hshift = hshift;
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db->maxmaxcode = maxmaxcode;
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db->maxbits = bits;
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return (void *) db;
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}
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static void *bsd_comp_alloc (unsigned char *options, int opt_len)
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{
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return bsd_alloc (options, opt_len, 0);
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}
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|
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static void *bsd_decomp_alloc (unsigned char *options, int opt_len)
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{
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return bsd_alloc (options, opt_len, 1);
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}
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|
|
/*
|
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* Initialize the database.
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*/
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|
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static int bsd_init (void *state, unsigned char *options,
|
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int opt_len, int unit, int debug, int decomp)
|
|
{
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struct bsd_db *db = state;
|
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int indx;
|
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|
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if ((opt_len != 3) || (options[0] != CI_BSD_COMPRESS) || (options[1] != 3)
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|| (BSD_VERSION(options[2]) != BSD_CURRENT_VERSION)
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|| (BSD_NBITS(options[2]) != db->maxbits)
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|| (decomp && db->lens == NULL))
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{
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return 0;
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}
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|
|
if (decomp)
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{
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indx = LAST;
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do
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{
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db->lens[indx] = 1;
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}
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while (indx-- > 0);
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}
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|
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indx = db->hsize;
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while (indx-- != 0)
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{
|
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db->dict[indx].codem1 = BADCODEM1;
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db->dict[indx].cptr = 0;
|
|
}
|
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|
|
db->unit = unit;
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|
db->mru = 0;
|
|
#ifndef DEBUG
|
|
if (debug)
|
|
#endif
|
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db->debug = 1;
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|
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bsd_reset(db);
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|
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return 1;
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}
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|
|
static int bsd_comp_init (void *state, unsigned char *options,
|
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int opt_len, int unit, int opthdr, int debug)
|
|
{
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return bsd_init (state, options, opt_len, unit, debug, 0);
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}
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|
|
static int bsd_decomp_init (void *state, unsigned char *options,
|
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int opt_len, int unit, int opthdr, int mru,
|
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int debug)
|
|
{
|
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return bsd_init (state, options, opt_len, unit, debug, 1);
|
|
}
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|
|
|
/*
|
|
* 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])
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|
|
#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));
|