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334 lines (266 loc) · 8.77 KB
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///////////////////////////////////////////////////////////////////////////////
//
/// \file index_hash.c
/// \brief Validates Index by using a hash function
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "common.h"
#include "index.h"
#include "check.h"
typedef struct {
/// Sum of the Block sizes (including Block Padding)
lzma_vli blocks_size;
/// Sum of the Uncompressed Size fields
lzma_vli uncompressed_size;
/// Number of Records
lzma_vli count;
/// Size of the List of Index Records as bytes
lzma_vli index_list_size;
/// Check calculated from Unpadded Sizes and Uncompressed Sizes.
lzma_check_state check;
} lzma_index_hash_info;
struct lzma_index_hash_s {
enum {
SEQ_BLOCK,
SEQ_COUNT,
SEQ_UNPADDED,
SEQ_UNCOMPRESSED,
SEQ_PADDING_INIT,
SEQ_PADDING,
SEQ_CRC32,
} sequence;
/// Information collected while decoding the actual Blocks.
lzma_index_hash_info blocks;
/// Information collected from the Index field.
lzma_index_hash_info records;
/// Number of Records not fully decoded
lzma_vli remaining;
/// Unpadded Size currently being read from an Index Record.
lzma_vli unpadded_size;
/// Uncompressed Size currently being read from an Index Record.
lzma_vli uncompressed_size;
/// Position in variable-length integers when decoding them from
/// the List of Records.
size_t pos;
/// CRC32 of the Index
uint32_t crc32;
};
extern LZMA_API(lzma_index_hash *)
lzma_index_hash_init(lzma_index_hash *index_hash,
const lzma_allocator *allocator)
{
if (index_hash == NULL) {
index_hash = lzma_alloc(sizeof(lzma_index_hash), allocator);
if (index_hash == NULL)
return NULL;
}
index_hash->sequence = SEQ_BLOCK;
index_hash->blocks.blocks_size = 0;
index_hash->blocks.uncompressed_size = 0;
index_hash->blocks.count = 0;
index_hash->blocks.index_list_size = 0;
index_hash->records.blocks_size = 0;
index_hash->records.uncompressed_size = 0;
index_hash->records.count = 0;
index_hash->records.index_list_size = 0;
index_hash->unpadded_size = 0;
index_hash->uncompressed_size = 0;
index_hash->pos = 0;
index_hash->crc32 = 0;
// These cannot fail because LZMA_CHECK_BEST is known to be supported.
(void)lzma_check_init(&index_hash->blocks.check, LZMA_CHECK_BEST);
(void)lzma_check_init(&index_hash->records.check, LZMA_CHECK_BEST);
return index_hash;
}
extern LZMA_API(void)
lzma_index_hash_end(lzma_index_hash *index_hash,
const lzma_allocator *allocator)
{
lzma_free(index_hash, allocator);
return;
}
extern LZMA_API(lzma_vli)
lzma_index_hash_size(const lzma_index_hash *index_hash)
{
// Get the size of the Index from ->blocks instead of ->records for
// cases where application wants to know the Index Size before
// decoding the Index.
return index_size(index_hash->blocks.count,
index_hash->blocks.index_list_size);
}
/// Updates the sizes and the hash without any validation.
static lzma_ret
hash_append(lzma_index_hash_info *info, lzma_vli unpadded_size,
lzma_vli uncompressed_size)
{
info->blocks_size += vli_ceil4(unpadded_size);
info->uncompressed_size += uncompressed_size;
info->index_list_size += lzma_vli_size(unpadded_size)
+ lzma_vli_size(uncompressed_size);
++info->count;
const lzma_vli sizes[2] = { unpadded_size, uncompressed_size };
lzma_check_update(&info->check, LZMA_CHECK_BEST,
(const uint8_t *)(sizes), sizeof(sizes));
return LZMA_OK;
}
extern LZMA_API(lzma_ret)
lzma_index_hash_append(lzma_index_hash *index_hash, lzma_vli unpadded_size,
lzma_vli uncompressed_size)
{
// Validate the arguments.
if (index_hash->sequence != SEQ_BLOCK
|| unpadded_size < UNPADDED_SIZE_MIN
|| unpadded_size > UNPADDED_SIZE_MAX
|| uncompressed_size > LZMA_VLI_MAX)
return LZMA_PROG_ERROR;
// Update the hash.
return_if_error(hash_append(&index_hash->blocks,
unpadded_size, uncompressed_size));
// Validate the properties of *info are still in allowed limits.
if (index_hash->blocks.blocks_size > LZMA_VLI_MAX
|| index_hash->blocks.uncompressed_size > LZMA_VLI_MAX
|| index_size(index_hash->blocks.count,
index_hash->blocks.index_list_size)
> LZMA_BACKWARD_SIZE_MAX
|| index_stream_size(index_hash->blocks.blocks_size,
index_hash->blocks.count,
index_hash->blocks.index_list_size)
> LZMA_VLI_MAX)
return LZMA_DATA_ERROR;
return LZMA_OK;
}
extern LZMA_API(lzma_ret)
lzma_index_hash_decode(lzma_index_hash *index_hash, const uint8_t *in,
size_t *in_pos, size_t in_size)
{
// Catch zero input buffer here, because in contrast to Index encoder
// and decoder functions, applications call this function directly
// instead of via lzma_code(), which does the buffer checking.
if (*in_pos >= in_size)
return LZMA_BUF_ERROR;
// NOTE: This function has many similarities to index_encode() and
// index_decode() functions found from index_encoder.c and
// index_decoder.c. See the comments especially in index_encoder.c.
const size_t in_start = *in_pos;
lzma_ret ret = LZMA_OK;
while (*in_pos < in_size)
switch (index_hash->sequence) {
case SEQ_BLOCK:
// Check the Index Indicator is present.
if (in[(*in_pos)++] != 0x00)
return LZMA_DATA_ERROR;
index_hash->sequence = SEQ_COUNT;
break;
case SEQ_COUNT: {
ret = lzma_vli_decode(&index_hash->remaining,
&index_hash->pos, in, in_pos, in_size);
if (ret != LZMA_STREAM_END)
goto out;
// The count must match the count of the Blocks decoded.
if (index_hash->remaining != index_hash->blocks.count)
return LZMA_DATA_ERROR;
ret = LZMA_OK;
index_hash->pos = 0;
// Handle the special case when there are no Blocks.
index_hash->sequence = index_hash->remaining == 0
? SEQ_PADDING_INIT : SEQ_UNPADDED;
break;
}
case SEQ_UNPADDED:
case SEQ_UNCOMPRESSED: {
lzma_vli *size = index_hash->sequence == SEQ_UNPADDED
? &index_hash->unpadded_size
: &index_hash->uncompressed_size;
ret = lzma_vli_decode(size, &index_hash->pos,
in, in_pos, in_size);
if (ret != LZMA_STREAM_END)
goto out;
ret = LZMA_OK;
index_hash->pos = 0;
if (index_hash->sequence == SEQ_UNPADDED) {
if (index_hash->unpadded_size < UNPADDED_SIZE_MIN
|| index_hash->unpadded_size
> UNPADDED_SIZE_MAX)
return LZMA_DATA_ERROR;
index_hash->sequence = SEQ_UNCOMPRESSED;
} else {
// Update the hash.
return_if_error(hash_append(&index_hash->records,
index_hash->unpadded_size,
index_hash->uncompressed_size));
// Verify that we don't go over the known sizes. Note
// that this validation is simpler than the one used
// in lzma_index_hash_append(), because here we know
// that values in index_hash->blocks are already
// validated and we are fine as long as we don't
// exceed them in index_hash->records.
if (index_hash->blocks.blocks_size
< index_hash->records.blocks_size
|| index_hash->blocks.uncompressed_size
< index_hash->records.uncompressed_size
|| index_hash->blocks.index_list_size
< index_hash->records.index_list_size)
return LZMA_DATA_ERROR;
// Check if this was the last Record.
index_hash->sequence = --index_hash->remaining == 0
? SEQ_PADDING_INIT : SEQ_UNPADDED;
}
break;
}
case SEQ_PADDING_INIT:
index_hash->pos = (LZMA_VLI_C(4) - index_size_unpadded(
index_hash->records.count,
index_hash->records.index_list_size)) & 3;
index_hash->sequence = SEQ_PADDING;
// Fall through
case SEQ_PADDING:
if (index_hash->pos > 0) {
--index_hash->pos;
if (in[(*in_pos)++] != 0x00)
return LZMA_DATA_ERROR;
break;
}
// Compare the sizes.
if (index_hash->blocks.blocks_size
!= index_hash->records.blocks_size
|| index_hash->blocks.uncompressed_size
!= index_hash->records.uncompressed_size
|| index_hash->blocks.index_list_size
!= index_hash->records.index_list_size)
return LZMA_DATA_ERROR;
// Finish the hashes and compare them.
lzma_check_finish(&index_hash->blocks.check, LZMA_CHECK_BEST);
lzma_check_finish(&index_hash->records.check, LZMA_CHECK_BEST);
if (memcmp(index_hash->blocks.check.buffer.u8,
index_hash->records.check.buffer.u8,
lzma_check_size(LZMA_CHECK_BEST)) != 0)
return LZMA_DATA_ERROR;
// Finish the CRC32 calculation.
index_hash->crc32 = lzma_crc32(in + in_start,
*in_pos - in_start, index_hash->crc32);
index_hash->sequence = SEQ_CRC32;
// Fall through
case SEQ_CRC32:
do {
if (*in_pos == in_size)
return LZMA_OK;
if (((index_hash->crc32 >> (index_hash->pos * 8))
& 0xFF) != in[(*in_pos)++])
return LZMA_DATA_ERROR;
} while (++index_hash->pos < 4);
return LZMA_STREAM_END;
default:
assert(0);
return LZMA_PROG_ERROR;
}
out:
// Update the CRC32,
index_hash->crc32 = lzma_crc32(in + in_start,
*in_pos - in_start, index_hash->crc32);
return ret;
}