diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..cfd6b41
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+snappy-fox
diff --git a/README.md b/README.md
index bdb67d1..334c017 100644
--- a/README.md
+++ b/README.md
@@ -4,8 +4,9 @@
-Snappy-fox is a morgue cache decompressor for Firefox which does not have
-dependencies.
+Snappy-fox is a Snappy file decompressor (i.e. morgue cache of Firefox)
+which does not have dependencies. It can also reconstruct corrupted
+files.
## Why?
Online applications such as whatsapp web (web.whatsapp.com) save cache
@@ -56,3 +57,22 @@ done
it will extract all your cache files in the
`/tmp/extracted-cache-whatsapp` directory.
+
+## Example
+
+You can try the application with the example image present in the
+example directory:
+```bash
+./snappy-fox example/exampleimage.snappy example/exampleimage.jpg
+```
+
+![example image](https://github.com/berdav/snappy-fox/blob/staging/example/exampleimage.jpg?raw=true)
+
+`alteredimage.snappy` is a corrupted version of the image, you can see
+the retrival performance of the tool using:
+```bash
+./snappy-fox --ignore_offset_errors example/alteredimage.snappy example/alteredimage.jpg
+```
+
+![altered image](https://github.com/berdav/snappy-fox/blob/staging/example/alteredimage.jpg?raw=true)
+
diff --git a/example/alteredimage.jpg b/example/alteredimage.jpg
new file mode 100644
index 0000000..56dc0ea
Binary files /dev/null and b/example/alteredimage.jpg differ
diff --git a/example/alteredimage.snappy b/example/alteredimage.snappy
new file mode 100644
index 0000000..7ddf0e5
Binary files /dev/null and b/example/alteredimage.snappy differ
diff --git a/example/alterrandom.py b/example/alterrandom.py
new file mode 100644
index 0000000..c70979b
--- /dev/null
+++ b/example/alterrandom.py
@@ -0,0 +1,18 @@
+import sys
+import random
+
+prob = int(sys.argv[3])
+substbyte = int(sys.argv[4])
+
+with open(sys.argv[1], "rb") as f:
+ indata = bytearray(f.read())
+
+for b in range(len(indata)):
+ x = random.randint(0, 10000)
+ if x < prob:
+ # Alter the data
+ indata[b] = substbyte
+
+with open(sys.argv[2], "wb") as f:
+ f.write(indata)
+
diff --git a/example/exampleimage.jpg b/example/exampleimage.jpg
new file mode 100644
index 0000000..f83e402
Binary files /dev/null and b/example/exampleimage.jpg differ
diff --git a/example/exampleimage.snappy b/example/exampleimage.snappy
new file mode 100644
index 0000000..0d95620
Binary files /dev/null and b/example/exampleimage.snappy differ
diff --git a/snappy-fox.c b/snappy-fox.c
index 0345ba2..93f8e48 100644
--- a/snappy-fox.c
+++ b/snappy-fox.c
@@ -23,6 +23,7 @@
#include
#include
#include
+#include
#define MAX_COMPRESSED_DATA_SIZE 16777211
#define MAX_UNCOMPRESSED_DATA_SIZE 65536
@@ -37,6 +38,103 @@
#define prbanner(f...) fprintf(stderr, f)
#define prerror(f...) fprintf(stderr, "[ ERROR ]"), fprintf(stderr, f)
+#ifndef VERSION
+#define VERSION "unknown"
+#endif
+
+/* Flags */
+/* Unframed file stream, by default assume framed file */
+static uint32_t unframed_stream = 0;
+/* Ignore offset errors, by default consider them as fatal errors*/
+static uint32_t ignore_offset_errors = 0;
+/* Byte to substitute offset corrupted values with */
+static uint8_t offset_dummy_byte = 0xff;
+/* Read offset */
+static uint32_t read_offset = 0;
+/* Consider CRC Errors */
+static uint32_t consider_crc_errors = 0;
+
+/* CRC related functions */
+static const uint32_t crc32c_table[] = {
+ 0x00000000, 0xf26b8303, 0xe13b70f7, 0x1350f3f4, 0xc79a971f,
+ 0x35f1141c, 0x26a1e7e8, 0xd4ca64eb, 0x8ad958cf, 0x78b2dbcc,
+ 0x6be22838, 0x9989ab3b, 0x4d43cfd0, 0xbf284cd3, 0xac78bf27,
+ 0x5e133c24, 0x105ec76f, 0xe235446c, 0xf165b798, 0x030e349b,
+ 0xd7c45070, 0x25afd373, 0x36ff2087, 0xc494a384, 0x9a879fa0,
+ 0x68ec1ca3, 0x7bbcef57, 0x89d76c54, 0x5d1d08bf, 0xaf768bbc,
+ 0xbc267848, 0x4e4dfb4b, 0x20bd8ede, 0xd2d60ddd, 0xc186fe29,
+ 0x33ed7d2a, 0xe72719c1, 0x154c9ac2, 0x061c6936, 0xf477ea35,
+ 0xaa64d611, 0x580f5512, 0x4b5fa6e6, 0xb93425e5, 0x6dfe410e,
+ 0x9f95c20d, 0x8cc531f9, 0x7eaeb2fa, 0x30e349b1, 0xc288cab2,
+ 0xd1d83946, 0x23b3ba45, 0xf779deae, 0x05125dad, 0x1642ae59,
+ 0xe4292d5a, 0xba3a117e, 0x4851927d, 0x5b016189, 0xa96ae28a,
+ 0x7da08661, 0x8fcb0562, 0x9c9bf696, 0x6ef07595, 0x417b1dbc,
+ 0xb3109ebf, 0xa0406d4b, 0x522bee48, 0x86e18aa3, 0x748a09a0,
+ 0x67dafa54, 0x95b17957, 0xcba24573, 0x39c9c670, 0x2a993584,
+ 0xd8f2b687, 0x0c38d26c, 0xfe53516f, 0xed03a29b, 0x1f682198,
+ 0x5125dad3, 0xa34e59d0, 0xb01eaa24, 0x42752927, 0x96bf4dcc,
+ 0x64d4cecf, 0x77843d3b, 0x85efbe38, 0xdbfc821c, 0x2997011f,
+ 0x3ac7f2eb, 0xc8ac71e8, 0x1c661503, 0xee0d9600, 0xfd5d65f4,
+ 0x0f36e6f7, 0x61c69362, 0x93ad1061, 0x80fde395, 0x72966096,
+ 0xa65c047d, 0x5437877e, 0x4767748a, 0xb50cf789, 0xeb1fcbad,
+ 0x197448ae, 0x0a24bb5a, 0xf84f3859, 0x2c855cb2, 0xdeeedfb1,
+ 0xcdbe2c45, 0x3fd5af46, 0x7198540d, 0x83f3d70e, 0x90a324fa,
+ 0x62c8a7f9, 0xb602c312, 0x44694011, 0x5739b3e5, 0xa55230e6,
+ 0xfb410cc2, 0x092a8fc1, 0x1a7a7c35, 0xe811ff36, 0x3cdb9bdd,
+ 0xceb018de, 0xdde0eb2a, 0x2f8b6829, 0x82f63b78, 0x709db87b,
+ 0x63cd4b8f, 0x91a6c88c, 0x456cac67, 0xb7072f64, 0xa457dc90,
+ 0x563c5f93, 0x082f63b7, 0xfa44e0b4, 0xe9141340, 0x1b7f9043,
+ 0xcfb5f4a8, 0x3dde77ab, 0x2e8e845f, 0xdce5075c, 0x92a8fc17,
+ 0x60c37f14, 0x73938ce0, 0x81f80fe3, 0x55326b08, 0xa759e80b,
+ 0xb4091bff, 0x466298fc, 0x1871a4d8, 0xea1a27db, 0xf94ad42f,
+ 0x0b21572c, 0xdfeb33c7, 0x2d80b0c4, 0x3ed04330, 0xccbbc033,
+ 0xa24bb5a6, 0x502036a5, 0x4370c551, 0xb11b4652, 0x65d122b9,
+ 0x97baa1ba, 0x84ea524e, 0x7681d14d, 0x2892ed69, 0xdaf96e6a,
+ 0xc9a99d9e, 0x3bc21e9d, 0xef087a76, 0x1d63f975, 0x0e330a81,
+ 0xfc588982, 0xb21572c9, 0x407ef1ca, 0x532e023e, 0xa145813d,
+ 0x758fe5d6, 0x87e466d5, 0x94b49521, 0x66df1622, 0x38cc2a06,
+ 0xcaa7a905, 0xd9f75af1, 0x2b9cd9f2, 0xff56bd19, 0x0d3d3e1a,
+ 0x1e6dcdee, 0xec064eed, 0xc38d26c4, 0x31e6a5c7, 0x22b65633,
+ 0xd0ddd530, 0x0417b1db, 0xf67c32d8, 0xe52cc12c, 0x1747422f,
+ 0x49547e0b, 0xbb3ffd08, 0xa86f0efc, 0x5a048dff, 0x8ecee914,
+ 0x7ca56a17, 0x6ff599e3, 0x9d9e1ae0, 0xd3d3e1ab, 0x21b862a8,
+ 0x32e8915c, 0xc083125f, 0x144976b4, 0xe622f5b7, 0xf5720643,
+ 0x07198540, 0x590ab964, 0xab613a67, 0xb831c993, 0x4a5a4a90,
+ 0x9e902e7b, 0x6cfbad78, 0x7fab5e8c, 0x8dc0dd8f, 0xe330a81a,
+ 0x115b2b19, 0x020bd8ed, 0xf0605bee, 0x24aa3f05, 0xd6c1bc06,
+ 0xc5914ff2, 0x37faccf1, 0x69e9f0d5, 0x9b8273d6, 0x88d28022,
+ 0x7ab90321, 0xae7367ca, 0x5c18e4c9, 0x4f48173d, 0xbd23943e,
+ 0xf36e6f75, 0x0105ec76, 0x12551f82, 0xe03e9c81, 0x34f4f86a,
+ 0xc69f7b69, 0xd5cf889d, 0x27a40b9e, 0x79b737ba, 0x8bdcb4b9,
+ 0x988c474d, 0x6ae7c44e, 0xbe2da0a5, 0x4c4623a6, 0x5f16d052,
+ 0xad7d5351
+};
+
+static uint32_t crc32c_lookup(uint8_t index) {
+ return crc32c_table[index & 0xff];
+}
+
+static void crc32c(uint32_t *crc, const uint8_t *data, size_t len)
+{
+ int i = 0;
+ for (i = 0 ; i < len; ++i) {
+ uint32_t tabval = crc32c_lookup(*crc ^ data[i]);
+ *crc = tabval ^ (*crc >> 8);
+ }
+}
+
+static void crc32c_init(uint32_t *crc) {
+ /* Initial value is 0 */
+ *crc = 0xffffffff;
+}
+
+static void crc32c_fini(uint32_t *crc) {
+ /* Final step is to reverse the CRC Value */
+ *crc ^= 0xffffffff;
+ /* Mask the CRC */
+ *crc = ((*crc >> 15) | (*crc << 17)) + 0xa282ead8;
+}
+
/* Logarithm base two of the number */
static uint32_t log2_32(uint32_t n) {
int32_t i = 0;
@@ -117,7 +215,7 @@ static int32_t parse_literal(uint8_t *cdata, uint32_t cidx, uint32_t clength,
if (*idx + clen > length)
return -1;
- prdebug("Copying literal %d bytes at (u:%d c:%d (%lu))\n",
+ prdebug("Copying literal %d bytes at (u:%d c:%d (%u))\n",
clen, *idx, offsetval, offsetval);
memcpy(&data[*idx], &cdata[offsetval], clen);
@@ -128,18 +226,28 @@ static int32_t parse_literal(uint8_t *cdata, uint32_t cidx, uint32_t clength,
static int offsetread(uint8_t *data, uint32_t *idx, uint32_t length,
uint32_t clen, uint32_t coff) {
+ int ret = 0;
uint32_t i;
prdebug("Copying %d bytes offset %d (pos: %d)\n",
clen, coff, *idx);
/* Ignore invalid offset */
if (*idx < coff || coff == 0)
- return -1;
+ ret = -1;
if (*idx + clen > length)
- return -1;
+ ret = -1;
- if (coff >= clen) {
+ /* Check if we can ignore errors */
+ if (ret != 0 && !ignore_offset_errors) {
+ prerror("Offset error\n");
+ } else if (ret != 0 && ignore_offset_errors) {
+ prinfo("Ignoring offset errors\n");
+ for (i = 0; i < clen; ++i)
+ data[*idx+i] = offset_dummy_byte;
+ *idx = *idx + clen;
+ ret = 0;
+ } else if (coff >= clen) {
memcpy(&data[*idx], &data[*idx - coff], clen);
*idx += clen;
} else {
@@ -150,7 +258,7 @@ static int offsetread(uint8_t *data, uint32_t *idx, uint32_t length,
memcpy(&data[*idx], &data[*idx - coff], clen % coff);
*idx += clen % coff;
}
- return 0;
+ return ret;
}
@@ -224,13 +332,15 @@ static int32_t parse_compressed_type(uint8_t compressed_type,
}
static int snappy_uncompress(FILE *out, uint8_t *cdata, size_t clength,
- uint8_t *data, size_t length, uint32_t *idx) {
+ uint8_t *data, size_t length, uint32_t *idx, uint32_t *crc) {
int32_t off = 0;
uint32_t cidx = 0;
uint32_t bytes = 0;
uint32_t len = 0;
uint8_t ctype = 0;
+ crc32c_init(crc);
+
*idx = 0;
prdebug("Decompressing %ld bytes\n", clength);
@@ -248,6 +358,9 @@ static int snappy_uncompress(FILE *out, uint8_t *cdata, size_t clength,
off = parse_compressed_type(ctype, cdata, cidx, clength,
data, idx, len);
if (off < 0) {
+ /* Calculate CRC */
+ crc32c(crc, data, *idx);
+ crc32c_fini(crc);
if (fwrite(data, 1, *idx, out) != *idx)
return off;
return off;
@@ -257,6 +370,9 @@ static int snappy_uncompress(FILE *out, uint8_t *cdata, size_t clength,
cidx += off;
}
+ crc32c(crc, data, *idx);
+ crc32c_fini(crc);
+
return 0;
}
@@ -264,6 +380,14 @@ static FILE *open_read_file(const char *file) {
FILE *in = stdin;
if (strcmp(file, "-") != 0)
in = fopen(file, "rb");
+ prdebug("Opening IN file: %s\n", file);
+ if (in == NULL)
+ return in;
+
+ if (read_offset != 0) {
+ prinfo("Seeking to offset %d\n", read_offset);
+ fseek(in, read_offset, SEEK_SET);
+ }
return in;
}
@@ -271,6 +395,7 @@ static FILE *open_write_file(const char *file) {
FILE *out = stdout;
if (strcmp(file, "-") != 0)
out = fopen(file, "wb");
+ prdebug("Opening OUT file: %s\n", file);
return out;
}
@@ -314,6 +439,7 @@ static int parse_compressed_data_chunk(FILE *in, FILE *out) {
uint32_t c_read_length = 0;
uint32_t crc = 0;
uint32_t idx = 0;
+ uint32_t uncompressed_crc = 0;
c_data = malloc(MAX_COMPRESSED_DATA_SIZE);
if (c_data == NULL) {
@@ -362,12 +488,20 @@ static int parse_compressed_data_chunk(FILE *in, FILE *out) {
c_read_length = fread(c_data, 1, c_length - 3, in);
if ((ret = snappy_uncompress(out, c_data, c_read_length,
- data, MAX_UNCOMPRESSED_DATA_SIZE, &idx)) != 0) {
+ data, MAX_UNCOMPRESSED_DATA_SIZE, &idx,
+ &uncompressed_crc)) != 0) {
goto return_point;
}
prinfo("End of decompression %lx\n", ftell(in));
+ if (crc != uncompressed_crc) {
+ prinfo("Corrupted File! Expected CRC: %08x Calculated CRC: %08x\n", crc, uncompressed_crc);
+ if (consider_crc_errors) {
+ ret = -1;
+ goto return_point;
+ }
+ }
if (fwrite(data, 1, idx, out) < idx) {
perror("fwrite");
@@ -417,7 +551,62 @@ static int parse_chunk(FILE *in, FILE *out, uint8_t chunktype) {
}
}
-static int snappy_decompress_frame(FILE *in, FILE *out) {
+static int snappy_decompress_unframed(FILE *in, FILE *out) {
+ int ret = 0;
+ int32_t r = 0;
+ uint32_t read_head = 0;
+ uint32_t write_head = 0;
+
+ uint8_t *inbuf, *outbuf;
+
+ int32_t read_size = MAX_COMPRESSED_DATA_SIZE;
+ int32_t write_size = MAX_COMPRESSED_DATA_SIZE;
+
+ inbuf = malloc(read_size);
+ if (inbuf == NULL) {
+ ret = -1;
+ goto return_point;
+ }
+
+ outbuf = malloc(write_size);
+ if (outbuf == NULL) {
+ ret = -1;
+ goto free_in;
+ }
+
+ read_size = fread(inbuf, 1, read_size, in);
+ if (read_size <= 0) {
+ ret = read_size;
+ goto free_out;
+ }
+
+ while (read_head < read_size) {
+ /* Skip unvalid compressed types, sledge */
+ uint8_t ctype = inbuf[read_head] & 0x03;
+ r = parse_compressed_type(ctype, inbuf, read_head, read_size,
+ outbuf, &write_head, write_size);
+ if (r < 0) {
+ prerror("parse_compressed_type: %d\n", r);
+ return r;
+ }
+
+ read_head += r;
+ prinfo("offset: %u\n", read_head);
+ }
+
+ r = fwrite(outbuf, 1, write_head, out);
+ if (r < 0)
+ ret = r;
+
+free_out:
+ free(outbuf);
+free_in:
+ free(inbuf);
+return_point:
+ return ret;
+}
+
+static int snappy_decompress_framed(FILE *in, FILE *out) {
int ret = 0;
uint8_t chunktype;
@@ -430,40 +619,105 @@ static int snappy_decompress_frame(FILE *in, FILE *out) {
return ret;
}
+static void version(const char *progname) {
+ fprintf(stderr, "%s Version: %s\n", progname, VERSION);
+}
+
static void usage(const char *progname) {
- fprintf(stderr, "Usage %s