Firefox CRC calculation

Staging is not staging anymore

.github/workflows/github-action-test-snappy-fox.yml

@@ -0,0 +1,28 @@
+name: Test and release application
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  test-application:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install prerequisites
+        run: |
+          sudo apt-get -y install build-essential
+
+      - name: Check out repository code
+        uses: actions/checkout@v2
+
+      - name: Run tests
+        working-directory: ./test
+        run: |
+          bash run-tests.sh
+
+      - uses: "marvinpinto/action-automatic-releases@latest"
+        with:
+          repo_token: "${{ secrets.GITHUB_TOKEN }}"
+          title: "snappy-fox"
+          files: |
+            snappy-fox

.gitignore

@@ -0,0 +1 @@
+snappy-fox

Makefile

@@ -1,4 +1,4 @@
-CFLAGS+=-Wall -Werror
+CFLAGS+=-Wall -Werror -DVERSION='"v0.3.0"'
 TARGET=snappy-fox
 
 .PHONY: all

README.md

@@ -4,8 +4,9 @@
 <img alt="GitHub" src="https://img.shields.io/github/license/berdav/snappy-fox.svg?color=blue">
 </a>
 
-Snappy-fox is a morgue cache decompressor for Firefox which does not have
+Snappy-fox is a Snappy file decompressor (i.e. morgue cache of Firefox)
-dependencies.
+which does not have dependencies. It can also reconstruct corrupted
+files.
 
 ## Why?
 Online applications such as whatsapp web (web.whatsapp.com) save cache
@@ -32,7 +33,7 @@ make
 
 You can add debug prints with
 ```bash
-make CFLAGS=DEBUG
+make CFLAGS=-DDEBUG
 ```
 
 ## How?
@@ -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/master/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/master/example/alteredimage.jpg?raw=true)
+

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)
+

snappy-fox.c

@@ -23,6 +23,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <getopt.h>
 
 #define MAX_COMPRESSED_DATA_SIZE   16777211
 #define MAX_UNCOMPRESSED_DATA_SIZE 65536
@@ -37,6 +38,108 @@
 #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;
+/* Use Firefox CRC32 implementation */
+static uint32_t firefox_crc = 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 of CRC */
+	*crc = 0xffffffff;
+}
+
+static void crc32c_fini(uint32_t *crc) {
+	/* Firefox uses unreversed CRCs */
+	if (!firefox_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 +220,7 @@ 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 +231,28 @@ 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 +263,7 @@ 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 +337,15 @@ 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 +363,9 @@ 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 +375,9 @@ 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 +385,14 @@ 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 +400,7 @@ 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 +444,7 @@ 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 +493,20 @@ 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 +556,62 @@ 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 +624,111 @@ 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 <input file> <output file>\n", progname);
+    fprintf(stderr, "Usage %s [options] <input file> <output file>\n",
+		    progname);
     fprintf(stderr, "  files can be specified as - for stdin or stdout\n");
+    fprintf(stderr, "  Options:\n");
+    fprintf(stderr, "    -C --consider_crc_errors                      Consider CRC errors as fatal\n");
+    fprintf(stderr, "    -E --ignore_offset_errors [substitution byte] Ignore any offset errors that occurs\n");
+    fprintf(stderr, "    -O --read_offset [offset]                     Start reading file from offset\n");
+    fprintf(stderr, "    -f --firefox                                  Use firefox's CRC algorithm\n");
+    fprintf(stderr, "    -u --unframed                                 Assume Unframed stream in input file\n");
+    fprintf(stderr, "    -h --help                                     This Help\n");
+    fprintf(stderr, "    -v --version                                  Print Version and exit\n");
 }
 
 int main(int argc, char **argv) {
+    int c = 0;
     int ret = 0;
     FILE *in, *out;
 
-    prdebug("Starting snappyturtle\n");
+    int option_idx = 0;
+    static struct option flags[] = {
+        {"consider_crc_errors",  no_argument,       0, 'C'},
+        {"ignore_offset_errors", optional_argument, 0, 'E'},
+        {"read_offset",          required_argument, 0, 'O'},
+        {"firefox",              no_argument,       0, 'f'},
+        {"unframed",             no_argument,       0, 'u'},
+        {"version",              no_argument,       0, 'v'},
+        {"help",                 no_argument,       0, 'h'},
+        {0,                      0,                 0, 0}
+    };
 
-    if (argc < 3) {
+    while (c != -1) {
+        c = getopt_long(argc, argv, "CO:E::fuhv", flags, &option_idx);
+        switch (c) {
+            case 'C':
+                consider_crc_errors = 1;
+                break;
+            case 'E':
+                ignore_offset_errors = 1;
+                /* Set the dummy byte to the passed value */
+                if (optarg != NULL)
+                    offset_dummy_byte = (strtol(optarg, NULL, 0) & 0xff);
+                break;
+            case 'O':
+                if (optarg != NULL)
+                    read_offset = strtol(optarg, NULL, 0);
+                break;
+            case 'f':
+                firefox_crc = 1;
+                break;
+            case 'u':
+                unframed_stream = 1;
+                break;
+            case 'h':
+                usage(argv[0]);
+                return 0;
+            case 'v':
+                version(argv[0]);
+                return 0;
+            default:
+                prerror("Unknown Option: %c\n", c);
+                continue;
+            case -1:
+                break;
+        }
+    }
+
+    prdebug("Starting snappy-fox\n");
+
+    if (argc - optind < 2) {
         usage(argv[0]);
         return 1;
     }
 
 #ifdef __AFL_LOOP
-    while (__AFL_LOOP(1000)) {
+    while (__AFL_LOOP(UINT32_MAX)) {
 #endif
-    in = open_read_file(argv[1]);
+    in = open_read_file(argv[optind]);
     if (in == NULL) {
-        perror("fopen");
+        perror("fopen read");
         ret = 1;
         goto exit_point;
     }
 
-    out = open_write_file(argv[2]);
+#ifdef __AFL_LOOP
+    ftell(in);
+#endif
+
+    out = open_write_file(argv[optind + 1]);
     if (out == NULL) {
-        perror("fopen");
+        perror("fopen write");
         ret = 1;
         goto close_in;
     }
 
-    if ((ret = snappy_decompress_frame(in, out)) != 0) {
+    if (unframed_stream == 0)
+        ret = snappy_decompress_framed(in, out);
+    else
+        ret = snappy_decompress_unframed(in, out);
+
+    if (ret != 0) {
         prerror("decompress %d\n", ret);
         goto return_point;
     }

test/run-tests.sh

@@ -0,0 +1,45 @@
+#!/bin/sh
+
+set -eu
+
+test000() {
+	echo "[Test 000  ] check compilation"
+	cd ..
+	# Standard compilation
+	echo "[Test 000 a] Debug compilation "
+	make CFLAGS=-DDEBUG clean all
+	file ./snappy-fox | grep -q ELF
+	echo "[Test 000 b] Normal compilation "
+	make clean all
+	file ./snappy-fox | grep -q ELF
+	echo "[Test 000  ] ok"
+}
+
+test001() {
+	echo "[Test 001  ]check standard framed run"
+	cd ..
+	echo "[Test 001 a] normal image"
+	./snappy-fox example/exampleimage.snappy example/exampleimage.jpg
+	file example/exampleimage.jpg | grep -q JPEG
+
+	# The example image is CRC corrupted (it uses firefox CRCs)
+	echo "[Test 001 b] CRC Corruption"
+	! ./snappy-fox --consider_crc_errors  \
+		example/exampleimage.snappy example/exampleimage.jpg
+
+	echo "[Test 001 b] Firefox CRC Test"
+	./snappy-fox --consider_crc_errors --firefox \
+		example/exampleimage.snappy example/exampleimage.jpg
+
+	# Test on the corrupted image
+	echo "[Test 001 c] Corrupted image"
+	! ./snappy-fox \
+		example/alteredimage.snappy example/alteredimage.jpg
+	echo "[Test 001 c] Corrupted image ignoring offset errors"
+	./snappy-fox --ignore_offset_errors \
+		example/alteredimage.snappy example/alteredimage.jpg
+	echo "[Test 001  ] ok"
+}
+
+( test000 )
+( test001 )