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Diffstat (limited to 'src/common/compress.c')
| -rw-r--r-- | src/common/compress.c | 377 |
1 files changed, 377 insertions, 0 deletions
diff --git a/src/common/compress.c b/src/common/compress.c new file mode 100644 index 0000000000..38b8184573 --- /dev/null +++ b/src/common/compress.c @@ -0,0 +1,377 @@ +/* Copyright (c) 2004, Roger Dingledine. + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2017, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file compress.c + * \brief Common compression API. + **/ + +#include "orconfig.h" + +#include <stdlib.h> +#include <stdio.h> +#include <assert.h> +#include <string.h> +#include "torint.h" + +#ifdef HAVE_NETINET_IN_H +#include <netinet/in.h> +#endif + +#include "util.h" +#include "torlog.h" +#include "compress.h" +#include "compress_lzma.h" +#include "compress_zlib.h" +#include "compress_zstd.h" + +/** @{ */ +/* These macros define the maximum allowable compression factor. Anything of + * size greater than CHECK_FOR_COMPRESSION_BOMB_AFTER is not allowed to + * have an uncompression factor (uncompressed size:compressed size ratio) of + * any greater than MAX_UNCOMPRESSION_FACTOR. + * + * Picking a value for MAX_UNCOMPRESSION_FACTOR is a trade-off: we want it to + * be small to limit the attack multiplier, but we also want it to be large + * enough so that no legitimate document --even ones we might invent in the + * future -- ever compresses by a factor of greater than + * MAX_UNCOMPRESSION_FACTOR. Within those parameters, there's a reasonably + * large range of possible values. IMO, anything over 8 is probably safe; IMO + * anything under 50 is probably sufficient. + */ +#define MAX_UNCOMPRESSION_FACTOR 25 +#define CHECK_FOR_COMPRESSION_BOMB_AFTER (1024*64) +/** @} */ + +/** Return true if uncompressing an input of size <b>in_size</b> to an input of + * size at least <b>size_out</b> looks like a compression bomb. */ +int +tor_compress_is_compression_bomb(size_t size_in, size_t size_out) +{ + if (size_in == 0 || size_out < CHECK_FOR_COMPRESSION_BOMB_AFTER) + return 0; + + return (size_out / size_in > MAX_UNCOMPRESSION_FACTOR); +} + +/** Given <b>in_len</b> bytes at <b>in</b>, compress them into a newly + * allocated buffer, using the method described in <b>method</b>. Store the + * compressed string in *<b>out</b>, and its length in *<b>out_len</b>. + * Return 0 on success, -1 on failure. + */ +int +tor_compress(char **out, size_t *out_len, + const char *in, size_t in_len, + compress_method_t method) +{ + switch (method) { + case GZIP_METHOD: + case ZLIB_METHOD: + return tor_zlib_compress(out, out_len, in, in_len, method); + case LZMA_METHOD: + return tor_lzma_compress(out, out_len, in, in_len, method); + case ZSTD_METHOD: + return tor_zstd_compress(out, out_len, in, in_len, method); + case NO_METHOD: + case UNKNOWN_METHOD: + default: + return -1; + } +} + +/** Given zero or more zlib-compressed or gzip-compressed strings of + * total length + * <b>in_len</b> bytes at <b>in</b>, uncompress them into a newly allocated + * buffer, using the method described in <b>method</b>. Store the uncompressed + * string in *<b>out</b>, and its length in *<b>out_len</b>. Return 0 on + * success, -1 on failure. + * + * If <b>complete_only</b> is true, we consider a truncated input as a + * failure; otherwise we decompress as much as we can. Warn about truncated + * or corrupt inputs at <b>protocol_warn_level</b>. + */ +int +tor_uncompress(char **out, size_t *out_len, + const char *in, size_t in_len, + compress_method_t method, + int complete_only, + int protocol_warn_level) +{ + switch (method) { + case GZIP_METHOD: + case ZLIB_METHOD: + return tor_zlib_uncompress(out, out_len, in, in_len, + method, + complete_only, + protocol_warn_level); + case LZMA_METHOD: + return tor_lzma_uncompress(out, out_len, in, in_len, + method, + complete_only, + protocol_warn_level); + case ZSTD_METHOD: + return tor_zstd_uncompress(out, out_len, in, in_len, + method, + complete_only, + protocol_warn_level); + case NO_METHOD: + case UNKNOWN_METHOD: + default: + return -1; + } +} + +/** Try to tell whether the <b>in_len</b>-byte string in <b>in</b> is likely + * to be compressed or not. If it is, return the likeliest compression method. + * Otherwise, return UNKNOWN_METHOD. + */ +compress_method_t +detect_compression_method(const char *in, size_t in_len) +{ + if (in_len > 2 && fast_memeq(in, "\x1f\x8b", 2)) { + return GZIP_METHOD; + } else if (in_len > 2 && (in[0] & 0x0f) == 8 && + (ntohs(get_uint16(in)) % 31) == 0) { + return ZLIB_METHOD; + } else if (in_len > 3 && + fast_memeq(in, "\x5d\x00\x00\x00", 4)) { + return LZMA_METHOD; + } else if (in_len > 3 && + fast_memeq(in, "\x28\xb5\x2f\xfd", 4)) { + return ZSTD_METHOD; + } else { + return UNKNOWN_METHOD; + } +} + +/** Return 1 if a given <b>method</b> is supported; otherwise 0. */ +int +tor_compress_supports_method(compress_method_t method) +{ + switch (method) { + case GZIP_METHOD: + case ZLIB_METHOD: + return tor_zlib_method_supported(); + case LZMA_METHOD: + return tor_lzma_method_supported(); + case ZSTD_METHOD: + return tor_zstd_method_supported(); + case NO_METHOD: + case UNKNOWN_METHOD: + default: + return 0; + } +} + +/** Return a string representation of the version of the library providing the + * compression method given in <b>method</b>. Returns NULL if <b>method</b> is + * unknown or unsupported. */ +const char * +tor_compress_version_str(compress_method_t method) +{ + switch (method) { + case GZIP_METHOD: + case ZLIB_METHOD: + return tor_zlib_get_version_str(); + case LZMA_METHOD: + return tor_lzma_get_version_str(); + case ZSTD_METHOD: + return tor_zstd_get_version_str(); + case NO_METHOD: + case UNKNOWN_METHOD: + default: + return NULL; + } +} + +/** Return a string representation of the version of the library, found at + * compile time, providing the compression method given in <b>method</b>. + * Returns NULL if <b>method</b> is unknown or unsupported. */ +const char * +tor_compress_header_version_str(compress_method_t method) +{ + switch (method) { + case GZIP_METHOD: + case ZLIB_METHOD: + return tor_zlib_get_header_version_str(); + case LZMA_METHOD: + return tor_lzma_get_header_version_str(); + case ZSTD_METHOD: + return tor_zstd_get_header_version_str(); + case NO_METHOD: + case UNKNOWN_METHOD: + default: + return NULL; + } +} + +/** Return the approximate number of bytes allocated for all + * supported compression schemas. */ +size_t +tor_compress_get_total_allocation(void) +{ + return tor_zlib_get_total_allocation() + + tor_lzma_get_total_allocation() + + tor_zstd_get_total_allocation(); +} + +/** Internal state for an incremental compression/decompression. The body of + * this struct is not exposed. */ +struct tor_compress_state_t { + compress_method_t method; /**< The compression method. */ + + union { + tor_zlib_compress_state_t *zlib_state; + tor_lzma_compress_state_t *lzma_state; + tor_zstd_compress_state_t *zstd_state; + } u; /**< Compression backend state. */ +}; + +/** Construct and return a tor_compress_state_t object using <b>method</b>. If + * <b>compress</b>, it's for compression; otherwise it's for decompression. */ +tor_compress_state_t * +tor_compress_new(int compress, compress_method_t method, + compression_level_t compression_level) +{ + tor_compress_state_t *state; + + state = tor_malloc_zero(sizeof(tor_compress_state_t)); + state->method = method; + + switch (method) { + case GZIP_METHOD: + case ZLIB_METHOD: { + tor_zlib_compress_state_t *zlib_state = + tor_zlib_compress_new(compress, method, compression_level); + + if (zlib_state == NULL) + goto err; + + state->u.zlib_state = zlib_state; + break; + } + case LZMA_METHOD: { + tor_lzma_compress_state_t *lzma_state = + tor_lzma_compress_new(compress, method, compression_level); + + if (lzma_state == NULL) + goto err; + + state->u.lzma_state = lzma_state; + break; + } + case ZSTD_METHOD: { + tor_zstd_compress_state_t *zstd_state = + tor_zstd_compress_new(compress, method, compression_level); + + if (zstd_state == NULL) + goto err; + + state->u.zstd_state = zstd_state; + break; + } + case NO_METHOD: + case UNKNOWN_METHOD: + goto err; + } + + return state; + + err: + tor_free(state); + return NULL; +} + +/** Compress/decompress some bytes using <b>state</b>. Read up to + * *<b>in_len</b> bytes from *<b>in</b>, and write up to *<b>out_len</b> bytes + * to *<b>out</b>, adjusting the values as we go. If <b>finish</b> is true, + * we've reached the end of the input. + * + * Return TOR_COMPRESS_DONE if we've finished the entire + * compression/decompression. + * Return TOR_COMPRESS_OK if we're processed everything from the input. + * Return TOR_COMPRESS_BUFFER_FULL if we're out of space on <b>out</b>. + * Return TOR_COMPRESS_ERROR if the stream is corrupt. + */ +tor_compress_output_t +tor_compress_process(tor_compress_state_t *state, + char **out, size_t *out_len, + const char **in, size_t *in_len, + int finish) +{ + tor_assert(state != NULL); + + switch (state->method) { + case GZIP_METHOD: + case ZLIB_METHOD: + return tor_zlib_compress_process(state->u.zlib_state, + out, out_len, in, in_len, + finish); + case LZMA_METHOD: + return tor_lzma_compress_process(state->u.lzma_state, + out, out_len, in, in_len, + finish); + case ZSTD_METHOD: + return tor_zstd_compress_process(state->u.zstd_state, + out, out_len, in, in_len, + finish); + case NO_METHOD: + case UNKNOWN_METHOD: + goto err; + } + + err: + return TOR_COMPRESS_ERROR; +} + +/** Deallocate <b>state</b>. */ +void +tor_compress_free(tor_compress_state_t *state) +{ + if (state == NULL) + return; + + switch (state->method) { + case GZIP_METHOD: + case ZLIB_METHOD: + tor_zlib_compress_free(state->u.zlib_state); + break; + case LZMA_METHOD: + tor_lzma_compress_free(state->u.lzma_state); + break; + case ZSTD_METHOD: + tor_zstd_compress_free(state->u.zstd_state); + break; + case NO_METHOD: + case UNKNOWN_METHOD: + break; + } + + tor_free(state); +} + +/** Return the approximate number of bytes allocated for <b>state</b>. */ +size_t +tor_compress_state_size(const tor_compress_state_t *state) +{ + tor_assert(state != NULL); + + switch (state->method) { + case GZIP_METHOD: + case ZLIB_METHOD: + return tor_zlib_compress_state_size(state->u.zlib_state); + case LZMA_METHOD: + return tor_lzma_compress_state_size(state->u.lzma_state); + case ZSTD_METHOD: + return tor_zstd_compress_state_size(state->u.zstd_state); + case NO_METHOD: + case UNKNOWN_METHOD: + goto err; + } + + err: + return 0; +} + |