Tor  0.4.7.0-alpha-dev
compress_zlib.c
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1 /* Copyright (c) 2004, Roger Dingledine.
2  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
3  * Copyright (c) 2007-2021, The Tor Project, Inc. */
4 /* See LICENSE for licensing information */
5 
6 /**
7  * \file compress_zlib.c
8  * \brief Compression backend for gzip and zlib.
9  *
10  * This module should never be invoked directly. Use the compress module
11  * instead.
12  **/
13 
14 #include "orconfig.h"
15 
16 #include "lib/log/log.h"
17 #include "lib/log/util_bug.h"
18 #include "lib/compress/compress.h"
20 #include "lib/thread/threads.h"
21 
22 /* zlib 1.2.4 and 1.2.5 do some "clever" things with macros. Instead of
23  saying "(defined(FOO) ? FOO : 0)" they like to say "FOO-0", on the theory
24  that nobody will care if the compile outputs a no-such-identifier warning.
25 
26  Sorry, but we like -Werror over here, so I guess we need to define these.
27  I hope that zlib 1.2.6 doesn't break these too.
28 */
29 #ifndef _LARGEFILE64_SOURCE
30 #define _LARGEFILE64_SOURCE 0
31 #endif
32 #ifndef _LFS64_LARGEFILE
33 #define _LFS64_LARGEFILE 0
34 #endif
35 #ifndef _FILE_OFFSET_BITS
36 #define _FILE_OFFSET_BITS 0
37 #endif
38 #ifndef off64_t
39 #define off64_t int64_t
40 #endif
41 
42 #include <zlib.h>
43 
44 #if defined ZLIB_VERNUM && ZLIB_VERNUM < 0x1200
45 #error "We require zlib version 1.2 or later."
46 #endif
47 
48 static size_t tor_zlib_state_size_precalc(int inflate,
49  int windowbits, int memlevel);
50 
51 /** Total number of bytes allocated for zlib state */
53 
54 /** Given <b>level</b> return the memory level. */
55 static int
57 {
58  switch (level) {
59  default:
60  case BEST_COMPRESSION: return 9;
61  case HIGH_COMPRESSION: return 8;
62  case MEDIUM_COMPRESSION: return 7;
63  case LOW_COMPRESSION: return 6;
64  }
65 }
66 
67 /** Return the 'bits' value to tell zlib to use <b>method</b>.*/
68 static inline int
70 {
71  /* Bits+16 means "use gzip" in zlib >= 1.2 */
72  const int flag = method == GZIP_METHOD ? 16 : 0;
73  switch (level) {
74  default:
75  case BEST_COMPRESSION:
76  case HIGH_COMPRESSION: return flag + 15;
77  case MEDIUM_COMPRESSION: return flag + 13;
78  case LOW_COMPRESSION: return flag + 11;
79  }
80 }
81 
82 /** Return 1 if zlib/gzip compression is supported; otherwise 0. */
83 int
85 {
86  /* We currently always support zlib/gzip, but we keep this function around in
87  * case we some day decide to deprecate zlib/gzip support.
88  */
89  return 1;
90 }
91 
92 /** Return a string representation of the version of the currently running
93  * version of zlib. */
94 const char *
96 {
97  return zlibVersion();
98 }
99 
100 /** Return a string representation of the version of the version of zlib
101 * used at compilation. */
102 const char *
104 {
105  return ZLIB_VERSION;
106 }
107 
108 /** Internal zlib state for an incremental compression/decompression.
109  * The body of this struct is not exposed. */
111  struct z_stream_s stream; /**< The zlib stream */
112  int compress; /**< True if we are compressing; false if we are inflating */
113 
114  /** Number of bytes read so far. Used to detect zlib bombs. */
115  size_t input_so_far;
116  /** Number of bytes written so far. Used to detect zlib bombs. */
118 
119  /** Approximate number of bytes allocated for this object. */
120  size_t allocation;
121 };
122 
123 /** Return an approximate number of bytes used in RAM to hold a state with
124  * window bits <b>windowBits</b> and compression level 'memlevel' */
125 static size_t
126 tor_zlib_state_size_precalc(int inflate_, int windowbits, int memlevel)
127 {
128  windowbits &= 15;
129 
130 #define A_FEW_KILOBYTES 2048
131 
132  if (inflate_) {
133  /* From zconf.h:
134 
135  "The memory requirements for inflate are (in bytes) 1 << windowBits
136  that is, 32K for windowBits=15 (default value) plus a few kilobytes
137  for small objects."
138  */
139  return sizeof(tor_zlib_compress_state_t) + sizeof(struct z_stream_s) +
140  (1 << 15) + A_FEW_KILOBYTES;
141  } else {
142  /* Also from zconf.h:
143 
144  "The memory requirements for deflate are (in bytes):
145  (1 << (windowBits+2)) + (1 << (memLevel+9))
146  ... plus a few kilobytes for small objects."
147  */
148  return sizeof(tor_zlib_compress_state_t) + sizeof(struct z_stream_s) +
149  (1 << (windowbits + 2)) + (1 << (memlevel + 9)) + A_FEW_KILOBYTES;
150  }
151 #undef A_FEW_KILOBYTES
152 }
153 
154 /** Construct and return a tor_zlib_compress_state_t object using
155  * <b>method</b>. If <b>compress</b>, it's for compression; otherwise it's for
156  * decompression. */
158 tor_zlib_compress_new(int compress_,
159  compress_method_t method,
160  compression_level_t compression_level)
161 {
163  int bits, memlevel;
164 
165  if (! compress_) {
166  /* use this setting for decompression, since we might have the
167  * max number of window bits */
168  compression_level = BEST_COMPRESSION;
169  }
170 
171  out = tor_malloc_zero(sizeof(tor_zlib_compress_state_t));
172  out->stream.zalloc = Z_NULL;
173  out->stream.zfree = Z_NULL;
174  out->stream.opaque = NULL;
175  out->compress = compress_;
176  bits = method_bits(method, compression_level);
177  memlevel = memory_level(compression_level);
178  if (compress_) {
179  if (deflateInit2(&out->stream, Z_BEST_COMPRESSION, Z_DEFLATED,
180  bits, memlevel,
181  Z_DEFAULT_STRATEGY) != Z_OK)
182  goto err; // LCOV_EXCL_LINE
183  } else {
184  if (inflateInit2(&out->stream, bits) != Z_OK)
185  goto err; // LCOV_EXCL_LINE
186  }
187  out->allocation = tor_zlib_state_size_precalc(!compress_, bits, memlevel);
188 
190 
191  return out;
192 
193  err:
194  tor_free(out);
195  return NULL;
196 }
197 
198 /** Compress/decompress some bytes using <b>state</b>. Read up to
199  * *<b>in_len</b> bytes from *<b>in</b>, and write up to *<b>out_len</b> bytes
200  * to *<b>out</b>, adjusting the values as we go. If <b>finish</b> is true,
201  * we've reached the end of the input.
202  *
203  * Return TOR_COMPRESS_DONE if we've finished the entire
204  * compression/decompression.
205  * Return TOR_COMPRESS_OK if we're processed everything from the input.
206  * Return TOR_COMPRESS_BUFFER_FULL if we're out of space on <b>out</b>.
207  * Return TOR_COMPRESS_ERROR if the stream is corrupt.
208  */
211  char **out, size_t *out_len,
212  const char **in, size_t *in_len,
213  int finish)
214 {
215  int err;
216  tor_assert(state != NULL);
217  if (*in_len > UINT_MAX ||
218  *out_len > UINT_MAX) {
219  return TOR_COMPRESS_ERROR;
220  }
221 
222  state->stream.next_in = (unsigned char*) *in;
223  state->stream.avail_in = (unsigned int)*in_len;
224  state->stream.next_out = (unsigned char*) *out;
225  state->stream.avail_out = (unsigned int)*out_len;
226 
227  if (state->compress) {
228  err = deflate(&state->stream, finish ? Z_FINISH : Z_NO_FLUSH);
229  } else {
230  err = inflate(&state->stream, finish ? Z_FINISH : Z_SYNC_FLUSH);
231  }
232 
233  state->input_so_far += state->stream.next_in - ((unsigned char*)*in);
234  state->output_so_far += state->stream.next_out - ((unsigned char*)*out);
235 
236  *out = (char*) state->stream.next_out;
237  *out_len = state->stream.avail_out;
238  *in = (const char *) state->stream.next_in;
239  *in_len = state->stream.avail_in;
240 
241  if (! state->compress &&
243  state->output_so_far)) {
244  log_warn(LD_DIR, "Possible zlib bomb; abandoning stream.");
245  return TOR_COMPRESS_ERROR;
246  }
247 
248  switch (err)
249  {
250  case Z_STREAM_END:
251  return TOR_COMPRESS_DONE;
252  case Z_BUF_ERROR:
253  if (state->stream.avail_in == 0 && !finish)
254  return TOR_COMPRESS_OK;
255  return TOR_COMPRESS_BUFFER_FULL;
256  case Z_OK:
257  if (state->stream.avail_out == 0 || finish)
258  return TOR_COMPRESS_BUFFER_FULL;
259  return TOR_COMPRESS_OK;
260  default:
261  log_warn(LD_GENERAL, "Gzip returned an error: %s",
262  state->stream.msg ? state->stream.msg : "<no message>");
263  return TOR_COMPRESS_ERROR;
264  }
265 }
266 
267 /** Deallocate <b>state</b>. */
268 void
270 {
271  if (state == NULL)
272  return;
273 
275 
276  if (state->compress)
277  deflateEnd(&state->stream);
278  else
279  inflateEnd(&state->stream);
280 
281  tor_free(state);
282 }
283 
284 /** Return the approximate number of bytes allocated for <b>state</b>. */
285 size_t
287 {
288  tor_assert(state != NULL);
289  return state->allocation;
290 }
291 
292 /** Return the approximate number of bytes allocated for all zlib states. */
293 size_t
295 {
297 }
298 
299 /** Set up global state for the zlib module */
300 void
302 {
304 }
void atomic_counter_init(atomic_counter_t *counter)
void atomic_counter_sub(atomic_counter_t *counter, size_t sub)
void atomic_counter_add(atomic_counter_t *counter, size_t add)
size_t atomic_counter_get(atomic_counter_t *counter)
int tor_compress_is_compression_bomb(size_t size_in, size_t size_out)
Definition: compress.c:64
Headers for compress.c.
tor_compress_output_t
Definition: compress.h:68
compress_method_t
Definition: compress.h:21
compression_level_t
Definition: compress.h:35
void tor_zlib_compress_free_(tor_zlib_compress_state_t *state)
static int memory_level(compression_level_t level)
Definition: compress_zlib.c:56
void tor_zlib_init(void)
const char * tor_zlib_get_header_version_str(void)
static size_t tor_zlib_state_size_precalc(int inflate, int windowbits, int memlevel)
int tor_zlib_method_supported(void)
Definition: compress_zlib.c:84
static int method_bits(compress_method_t method, compression_level_t level)
Definition: compress_zlib.c:69
static atomic_counter_t total_zlib_allocation
Definition: compress_zlib.c:52
size_t tor_zlib_get_total_allocation(void)
tor_zlib_compress_state_t * tor_zlib_compress_new(int compress_, compress_method_t method, compression_level_t compression_level)
size_t tor_zlib_compress_state_size(const tor_zlib_compress_state_t *state)
const char * tor_zlib_get_version_str(void)
Definition: compress_zlib.c:95
tor_compress_output_t tor_zlib_compress_process(tor_zlib_compress_state_t *state, char **out, size_t *out_len, const char **in, size_t *in_len, int finish)
Header for compress_zlib.c.
Headers for log.c.
#define LD_GENERAL
Definition: log.h:62
#define LD_DIR
Definition: log.h:88
#define tor_free(p)
Definition: malloc.h:52
struct z_stream_s stream
Header for threads.c.
Macros to manage assertions, fatal and non-fatal.
#define tor_assert(expr)
Definition: util_bug.h:102