// SPDX-License-Identifier: GPL-2.0-only /* * ppp_deflate.c - interface the zlib procedures for Deflate compression * and decompression (as used by gzip) to the PPP code. * * Copyright 1994-1998 Paul Mackerras. */ #include <linux/module.h> #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/init.h> #include <linux/string.h> #include <linux/ppp_defs.h> #include <linux/ppp-comp.h> #include <linux/zlib.h> #include <linux/unaligned.h> /* * State for a Deflate (de)compressor. */ struct ppp_deflate_state { … }; #define DEFLATE_OVHD … static void *z_comp_alloc(unsigned char *options, int opt_len); static void *z_decomp_alloc(unsigned char *options, int opt_len); static void z_comp_free(void *state); static void z_decomp_free(void *state); static int z_comp_init(void *state, unsigned char *options, int opt_len, int unit, int hdrlen, int debug); static int z_decomp_init(void *state, unsigned char *options, int opt_len, int unit, int hdrlen, int mru, int debug); static int z_compress(void *state, unsigned char *rptr, unsigned char *obuf, int isize, int osize); static void z_incomp(void *state, unsigned char *ibuf, int icnt); static int z_decompress(void *state, unsigned char *ibuf, int isize, unsigned char *obuf, int osize); static void z_comp_reset(void *state); static void z_decomp_reset(void *state); static void z_comp_stats(void *state, struct compstat *stats); /** * z_comp_free - free the memory used by a compressor * @arg: pointer to the private state for the compressor. */ static void z_comp_free(void *arg) { … } /** * z_comp_alloc - allocate space for a compressor. * @options: pointer to CCP option data * @opt_len: length of the CCP option at @options. * * The @options pointer points to the a buffer containing the * CCP option data for the compression being negotiated. It is * formatted according to RFC1979, and describes the window * size that the peer is requesting that we use in compressing * data to be sent to it. * * Returns the pointer to the private state for the compressor, * or NULL if we could not allocate enough memory. */ static void *z_comp_alloc(unsigned char *options, int opt_len) { … } /** * z_comp_init - initialize a previously-allocated compressor. * @arg: pointer to the private state for the compressor * @options: pointer to the CCP option data describing the * compression that was negotiated with the peer * @opt_len: length of the CCP option data at @options * @unit: PPP unit number for diagnostic messages * @hdrlen: ignored (present for backwards compatibility) * @debug: debug flag; if non-zero, debug messages are printed. * * The CCP options described by @options must match the options * specified when the compressor was allocated. The compressor * history is reset. Returns 0 for failure (CCP options don't * match) or 1 for success. */ static int z_comp_init(void *arg, unsigned char *options, int opt_len, int unit, int hdrlen, int debug) { … } /** * z_comp_reset - reset a previously-allocated compressor. * @arg: pointer to private state for the compressor. * * This clears the history for the compressor and makes it * ready to start emitting a new compressed stream. */ static void z_comp_reset(void *arg) { … } /** * z_compress - compress a PPP packet with Deflate compression. * @arg: pointer to private state for the compressor * @rptr: uncompressed packet (input) * @obuf: compressed packet (output) * @isize: size of uncompressed packet * @osize: space available at @obuf * * Returns the length of the compressed packet, or 0 if the * packet is incompressible. */ static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf, int isize, int osize) { … } /** * z_comp_stats - return compression statistics for a compressor * or decompressor. * @arg: pointer to private space for the (de)compressor * @stats: pointer to a struct compstat to receive the result. */ static void z_comp_stats(void *arg, struct compstat *stats) { … } /** * z_decomp_free - Free the memory used by a decompressor. * @arg: pointer to private space for the decompressor. */ static void z_decomp_free(void *arg) { … } /** * z_decomp_alloc - allocate space for a decompressor. * @options: pointer to CCP option data * @opt_len: length of the CCP option at @options. * * The @options pointer points to the a buffer containing the * CCP option data for the compression being negotiated. It is * formatted according to RFC1979, and describes the window * size that we are requesting the peer to use in compressing * data to be sent to us. * * Returns the pointer to the private state for the decompressor, * or NULL if we could not allocate enough memory. */ static void *z_decomp_alloc(unsigned char *options, int opt_len) { … } /** * z_decomp_init - initialize a previously-allocated decompressor. * @arg: pointer to the private state for the decompressor * @options: pointer to the CCP option data describing the * compression that was negotiated with the peer * @opt_len: length of the CCP option data at @options * @unit: PPP unit number for diagnostic messages * @hdrlen: ignored (present for backwards compatibility) * @mru: maximum length of decompressed packets * @debug: debug flag; if non-zero, debug messages are printed. * * The CCP options described by @options must match the options * specified when the decompressor was allocated. The decompressor * history is reset. Returns 0 for failure (CCP options don't * match) or 1 for success. */ static int z_decomp_init(void *arg, unsigned char *options, int opt_len, int unit, int hdrlen, int mru, int debug) { … } /** * z_decomp_reset - reset a previously-allocated decompressor. * @arg: pointer to private state for the decompressor. * * This clears the history for the decompressor and makes it * ready to receive a new compressed stream. */ static void z_decomp_reset(void *arg) { … } /** * z_decompress - decompress a Deflate-compressed packet. * @arg: pointer to private state for the decompressor * @ibuf: pointer to input (compressed) packet data * @isize: length of input packet * @obuf: pointer to space for output (decompressed) packet * @osize: amount of space available at @obuf * * 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 z_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf, int osize) { … } /** * z_incomp - add incompressible input data to the history. * @arg: pointer to private state for the decompressor * @ibuf: pointer to input packet data * @icnt: length of input data. */ static void z_incomp(void *arg, unsigned char *ibuf, int icnt) { … } /************************************************************* * Module interface table *************************************************************/ /* These are in ppp_generic.c */ extern int ppp_register_compressor (struct compressor *cp); extern void ppp_unregister_compressor (struct compressor *cp); /* * Procedures exported to if_ppp.c. */ static struct compressor ppp_deflate = …; static struct compressor ppp_deflate_draft = …; static int __init deflate_init(void) { … } static void __exit deflate_cleanup(void) { … } module_init(…) …; module_exit(deflate_cleanup); MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS(…) …; MODULE_ALIAS(…) …;
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