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1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file       index_hash.c
4 /// \brief      Validates Index by using a hash function
5 //
6 //  Author:     Lasse Collin
7 //
8 //  This file has been put into the public domain.
9 //  You can do whatever you want with this file.
10 //
11 ///////////////////////////////////////////////////////////////////////////////
12
13 #include "common.h"
14 #include "index.h"
15 #include "check.h"
16
17
18 typedef struct {
19         /// Sum of the Block sizes (including Block Padding)
20         lzma_vli blocks_size;
21
22         /// Sum of the Uncompressed Size fields
23         lzma_vli uncompressed_size;
24
25         /// Number of Records
26         lzma_vli count;
27
28         /// Size of the List of Index Records as bytes
29         lzma_vli index_list_size;
30
31         /// Check calculated from Unpadded Sizes and Uncompressed Sizes.
32         lzma_check_state check;
33
34 } lzma_index_hash_info;
35
36
37 struct lzma_index_hash_s {
38         enum {
39                 SEQ_BLOCK,
40                 SEQ_COUNT,
41                 SEQ_UNPADDED,
42                 SEQ_UNCOMPRESSED,
43                 SEQ_PADDING_INIT,
44                 SEQ_PADDING,
45                 SEQ_CRC32,
46         } sequence;
47
48         /// Information collected while decoding the actual Blocks.
49         lzma_index_hash_info blocks;
50
51         /// Information collected from the Index field.
52         lzma_index_hash_info records;
53
54         /// Number of Records not fully decoded
55         lzma_vli remaining;
56
57         /// Unpadded Size currently being read from an Index Record.
58         lzma_vli unpadded_size;
59
60         /// Uncompressed Size currently being read from an Index Record.
61         lzma_vli uncompressed_size;
62
63         /// Position in variable-length integers when decoding them from
64         /// the List of Records.
65         size_t pos;
66
67         /// CRC32 of the Index
68         uint32_t crc32;
69 };
70
71
72 extern LZMA_API(lzma_index_hash *)
73 lzma_index_hash_init(lzma_index_hash *index_hash,
74                 const lzma_allocator *allocator)
75 {
76         if (index_hash == NULL) {
77                 index_hash = lzma_alloc(sizeof(lzma_index_hash), allocator);
78                 if (index_hash == NULL)
79                         return NULL;
80         }
81
82         index_hash->sequence = SEQ_BLOCK;
83         index_hash->blocks.blocks_size = 0;
84         index_hash->blocks.uncompressed_size = 0;
85         index_hash->blocks.count = 0;
86         index_hash->blocks.index_list_size = 0;
87         index_hash->records.blocks_size = 0;
88         index_hash->records.uncompressed_size = 0;
89         index_hash->records.count = 0;
90         index_hash->records.index_list_size = 0;
91         index_hash->unpadded_size = 0;
92         index_hash->uncompressed_size = 0;
93         index_hash->pos = 0;
94         index_hash->crc32 = 0;
95
96         // These cannot fail because LZMA_CHECK_BEST is known to be supported.
97         (void)lzma_check_init(&index_hash->blocks.check, LZMA_CHECK_BEST);
98         (void)lzma_check_init(&index_hash->records.check, LZMA_CHECK_BEST);
99
100         return index_hash;
101 }
102
103
104 extern LZMA_API(void)
105 lzma_index_hash_end(lzma_index_hash *index_hash,
106                 const lzma_allocator *allocator)
107 {
108         lzma_free(index_hash, allocator);
109         return;
110 }
111
112
113 extern LZMA_API(lzma_vli)
114 lzma_index_hash_size(const lzma_index_hash *index_hash)
115 {
116         // Get the size of the Index from ->blocks instead of ->records for
117         // cases where application wants to know the Index Size before
118         // decoding the Index.
119         return index_size(index_hash->blocks.count,
120                         index_hash->blocks.index_list_size);
121 }
122
123
124 /// Updates the sizes and the hash without any validation.
125 static lzma_ret
126 hash_append(lzma_index_hash_info *info, lzma_vli unpadded_size,
127                 lzma_vli uncompressed_size)
128 {
129         info->blocks_size += vli_ceil4(unpadded_size);
130         info->uncompressed_size += uncompressed_size;
131         info->index_list_size += lzma_vli_size(unpadded_size)
132                         + lzma_vli_size(uncompressed_size);
133         ++info->count;
134
135         const lzma_vli sizes[2] = { unpadded_size, uncompressed_size };
136         lzma_check_update(&info->check, LZMA_CHECK_BEST,
137                         (const uint8_t *)(sizes), sizeof(sizes));
138
139         return LZMA_OK;
140 }
141
142
143 extern LZMA_API(lzma_ret)
144 lzma_index_hash_append(lzma_index_hash *index_hash, lzma_vli unpadded_size,
145                 lzma_vli uncompressed_size)
146 {
147         // Validate the arguments.
148         if (index_hash->sequence != SEQ_BLOCK
149                         || unpadded_size < UNPADDED_SIZE_MIN
150                         || unpadded_size > UNPADDED_SIZE_MAX
151                         || uncompressed_size > LZMA_VLI_MAX)
152                 return LZMA_PROG_ERROR;
153
154         // Update the hash.
155         return_if_error(hash_append(&index_hash->blocks,
156                         unpadded_size, uncompressed_size));
157
158         // Validate the properties of *info are still in allowed limits.
159         if (index_hash->blocks.blocks_size > LZMA_VLI_MAX
160                         || index_hash->blocks.uncompressed_size > LZMA_VLI_MAX
161                         || index_size(index_hash->blocks.count,
162                                         index_hash->blocks.index_list_size)
163                                 > LZMA_BACKWARD_SIZE_MAX
164                         || index_stream_size(index_hash->blocks.blocks_size,
165                                         index_hash->blocks.count,
166                                         index_hash->blocks.index_list_size)
167                                 > LZMA_VLI_MAX)
168                 return LZMA_DATA_ERROR;
169
170         return LZMA_OK;
171 }
172
173
174 extern LZMA_API(lzma_ret)
175 lzma_index_hash_decode(lzma_index_hash *index_hash, const uint8_t *in,
176                 size_t *in_pos, size_t in_size)
177 {
178         // Catch zero input buffer here, because in contrast to Index encoder
179         // and decoder functions, applications call this function directly
180         // instead of via lzma_code(), which does the buffer checking.
181         if (*in_pos >= in_size)
182                 return LZMA_BUF_ERROR;
183
184         // NOTE: This function has many similarities to index_encode() and
185         // index_decode() functions found from index_encoder.c and
186         // index_decoder.c. See the comments especially in index_encoder.c.
187         const size_t in_start = *in_pos;
188         lzma_ret ret = LZMA_OK;
189
190         while (*in_pos < in_size)
191         switch (index_hash->sequence) {
192         case SEQ_BLOCK:
193                 // Check the Index Indicator is present.
194                 if (in[(*in_pos)++] != 0x00)
195                         return LZMA_DATA_ERROR;
196
197                 index_hash->sequence = SEQ_COUNT;
198                 break;
199
200         case SEQ_COUNT: {
201                 ret = lzma_vli_decode(&index_hash->remaining,
202                                 &index_hash->pos, in, in_pos, in_size);
203                 if (ret != LZMA_STREAM_END)
204                         goto out;
205
206                 // The count must match the count of the Blocks decoded.
207                 if (index_hash->remaining != index_hash->blocks.count)
208                         return LZMA_DATA_ERROR;
209
210                 ret = LZMA_OK;
211                 index_hash->pos = 0;
212
213                 // Handle the special case when there are no Blocks.
214                 index_hash->sequence = index_hash->remaining == 0
215                                 ? SEQ_PADDING_INIT : SEQ_UNPADDED;
216                 break;
217         }
218
219         case SEQ_UNPADDED:
220         case SEQ_UNCOMPRESSED: {
221                 lzma_vli *size = index_hash->sequence == SEQ_UNPADDED
222                                 ? &index_hash->unpadded_size
223                                 : &index_hash->uncompressed_size;
224
225                 ret = lzma_vli_decode(size, &index_hash->pos,
226                                 in, in_pos, in_size);
227                 if (ret != LZMA_STREAM_END)
228                         goto out;
229
230                 ret = LZMA_OK;
231                 index_hash->pos = 0;
232
233                 if (index_hash->sequence == SEQ_UNPADDED) {
234                         if (index_hash->unpadded_size < UNPADDED_SIZE_MIN
235                                         || index_hash->unpadded_size
236                                                 > UNPADDED_SIZE_MAX)
237                                 return LZMA_DATA_ERROR;
238
239                         index_hash->sequence = SEQ_UNCOMPRESSED;
240                 } else {
241                         // Update the hash.
242                         return_if_error(hash_append(&index_hash->records,
243                                         index_hash->unpadded_size,
244                                         index_hash->uncompressed_size));
245
246                         // Verify that we don't go over the known sizes. Note
247                         // that this validation is simpler than the one used
248                         // in lzma_index_hash_append(), because here we know
249                         // that values in index_hash->blocks are already
250                         // validated and we are fine as long as we don't
251                         // exceed them in index_hash->records.
252                         if (index_hash->blocks.blocks_size
253                                         < index_hash->records.blocks_size
254                                         || index_hash->blocks.uncompressed_size
255                                         < index_hash->records.uncompressed_size
256                                         || index_hash->blocks.index_list_size
257                                         < index_hash->records.index_list_size)
258                                 return LZMA_DATA_ERROR;
259
260                         // Check if this was the last Record.
261                         index_hash->sequence = --index_hash->remaining == 0
262                                         ? SEQ_PADDING_INIT : SEQ_UNPADDED;
263                 }
264
265                 break;
266         }
267
268         case SEQ_PADDING_INIT:
269                 index_hash->pos = (LZMA_VLI_C(4) - index_size_unpadded(
270                                 index_hash->records.count,
271                                 index_hash->records.index_list_size)) & 3;
272                 index_hash->sequence = SEQ_PADDING;
273
274         // Fall through
275
276         case SEQ_PADDING:
277                 if (index_hash->pos > 0) {
278                         --index_hash->pos;
279                         if (in[(*in_pos)++] != 0x00)
280                                 return LZMA_DATA_ERROR;
281
282                         break;
283                 }
284
285                 // Compare the sizes.
286                 if (index_hash->blocks.blocks_size
287                                 != index_hash->records.blocks_size
288                                 || index_hash->blocks.uncompressed_size
289                                 != index_hash->records.uncompressed_size
290                                 || index_hash->blocks.index_list_size
291                                 != index_hash->records.index_list_size)
292                         return LZMA_DATA_ERROR;
293
294                 // Finish the hashes and compare them.
295                 lzma_check_finish(&index_hash->blocks.check, LZMA_CHECK_BEST);
296                 lzma_check_finish(&index_hash->records.check, LZMA_CHECK_BEST);
297                 if (memcmp(index_hash->blocks.check.buffer.u8,
298                                 index_hash->records.check.buffer.u8,
299                                 lzma_check_size(LZMA_CHECK_BEST)) != 0)
300                         return LZMA_DATA_ERROR;
301
302                 // Finish the CRC32 calculation.
303                 index_hash->crc32 = lzma_crc32(in + in_start,
304                                 *in_pos - in_start, index_hash->crc32);
305
306                 index_hash->sequence = SEQ_CRC32;
307
308         // Fall through
309
310         case SEQ_CRC32:
311                 do {
312                         if (*in_pos == in_size)
313                                 return LZMA_OK;
314
315                         if (((index_hash->crc32 >> (index_hash->pos * 8))
316                                         & 0xFF) != in[(*in_pos)++])
317                                 return LZMA_DATA_ERROR;
318
319                 } while (++index_hash->pos < 4);
320
321                 return LZMA_STREAM_END;
322
323         default:
324                 assert(0);
325                 return LZMA_PROG_ERROR;
326         }
327
328 out:
329         // Update the CRC32,
330         index_hash->crc32 = lzma_crc32(in + in_start,
331                         *in_pos - in_start, index_hash->crc32);
332
333         return ret;
334 }