src/common/compress.h

   1 /* Copyright (c) 2003, Roger Dingledine
   2  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   3  * Copyright (c) 2007-2017, The Tor Project, Inc. */
   4 /* See LICENSE for licensing information */
   5
   6 /**
   7  * \file compress.h
   8  * \brief Headers for compress.c
   9  **/
  10
  11 #ifndef TOR_COMPRESS_H
  12 #define TOR_COMPRESS_H
  13
  14 /** Enumeration of what kind of compression to use.  Only ZLIB_METHOD and
  15  * GZIP_METHOD is guaranteed to be supported by the compress/uncompress
  16  * functions here. Call tor_compress_supports_method() to check if a given
  17  * compression schema is supported by Tor. */
  18 typedef enum {
  19   NO_METHOD=0, // This method must be first.
  20   GZIP_METHOD=1,
  21   ZLIB_METHOD=2,
  22   LZMA_METHOD=3,
  23   ZSTD_METHOD=4,
  24   UNKNOWN_METHOD=5, // This method must be last. Add new ones in the middle.
  25 } compress_method_t;
  26
  27 /**
  28  * Enumeration to define tradeoffs between memory usage and compression level.
  29  * BEST_COMPRESSION saves the most bandwidth; LOW_COMPRESSION saves the most
  30  * memory.
  31  **/
  32 typedef enum {
  33   BEST_COMPRESSION, HIGH_COMPRESSION, MEDIUM_COMPRESSION, LOW_COMPRESSION
  34 } compression_level_t;
  35
  36 int tor_compress(char **out, size_t *out_len,
  37                  const char *in, size_t in_len,
  38                  compress_method_t method);
  39
  40 int tor_uncompress(char **out, size_t *out_len,
  41                    const char *in, size_t in_len,
  42                    compress_method_t method,
  43                    int complete_only,
  44                    int protocol_warn_level);
  45
  46 compress_method_t detect_compression_method(const char *in, size_t in_len);
  47
  48 int tor_compress_is_compression_bomb(size_t size_in, size_t size_out);
  49
  50 int tor_compress_supports_method(compress_method_t method);
  51 unsigned tor_compress_get_supported_method_bitmask(void);
  52 const char *compression_method_get_name(compress_method_t method);
  53 const char *compression_method_get_human_name(compress_method_t method);
  54 compress_method_t compression_method_get_by_name(const char *name);
  55
  56 const char *tor_compress_version_str(compress_method_t method);
  57
  58 const char *tor_compress_header_version_str(compress_method_t method);
  59
  60 size_t tor_compress_get_total_allocation(void);
  61
  62 /** Return values from tor_compress_process; see that function's documentation
  63  * for details. */
  64 typedef enum {
  65   TOR_COMPRESS_OK,
  66   TOR_COMPRESS_DONE,
  67   TOR_COMPRESS_BUFFER_FULL,
  68   TOR_COMPRESS_ERROR
  69 } tor_compress_output_t;
  70
  71 /** Internal state for an incremental compression/decompression. */
  72 typedef struct tor_compress_state_t tor_compress_state_t;
  73
  74 tor_compress_state_t *tor_compress_new(int compress,
  75                                        compress_method_t method,
  76                                        compression_level_t level);
  77
  78 tor_compress_output_t tor_compress_process(tor_compress_state_t *state,
  79                                            char **out, size_t *out_len,
  80                                            const char **in, size_t *in_len,
  81                                            int finish);
  82 void tor_compress_free(tor_compress_state_t *state);
  83
  84 size_t tor_compress_state_size(const tor_compress_state_t *state);
  85
  86 void tor_compress_init(void);
  87
  88 #endif // TOR_COMPRESS_H.
  89