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/*
* lib/ext2fs/digest_encode.c
*
* A function to encode a digest using 64 characters that are valid in a
* filename per ext2fs rules.
*
* Written by Uday Savagaonkar, 2014.
*
* Copyright 2014 Google Inc. All Rights Reserved.
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Library
* General Public License, version 2.
* %End-Header%
*/
#include "config.h"
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include "ext2fs.h"
static const char *lookup_table =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
/**
* ext2fs_digest_encode() -
*
* Encodes the input digest using characters from the set [a-zA-Z0-9_+].
* The encoded string is roughly 4/3 times the size of the input string.
*/
int ext2fs_digest_encode(const char *src, int len, char *dst)
{
int i = 0, bits = 0, ac = 0;
char *cp = dst;
while (i < len) {
ac += (((unsigned char) src[i]) << bits);
bits += 8;
do {
*cp++ = lookup_table[ac & 0x3f];
ac >>= 6;
bits -= 6;
} while (bits >= 6);
i++;
}
if (bits)
*cp++ = lookup_table[ac & 0x3f];
return cp - dst;
}
int ext2fs_digest_decode(const char *src, int len, char *dst)
{
int i = 0, bits = 0, ac = 0;
const char *p;
char *cp = dst;
while (i < len) {
p = strchr(lookup_table, src[i]);
if (p == NULL || src[i] == 0)
return -1;
ac += (p - lookup_table) << bits;
bits += 6;
if (bits >= 8) {
*cp++ = ac & 0xff;
ac >>= 8;
bits -= 8;
}
i++;
}
if (ac)
return -1;
return cp - dst;
}
#ifdef UNITTEST
static const struct {
unsigned char d[32];
unsigned int len;
const char *ed;
} tests[] = {
{ { 0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14,
0x9a, 0xfb, 0xf4, 0xc8, 0x99, 0x6f, 0xb9, 0x24,
0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b, 0x93, 0x4c,
0xa4, 0x95, 0x99, 0x1b, 0x78, 0x52, 0xb8, 0x55 }, 32,
"jDLxChJ,cQhm7TPyZ+WukcirBROZbOJTkWZmbgnU4WF"
},
{ { 0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad }, 32,
"6inF,+YAPreQBBk3d5qIjA7AhNqlXoHn0Cx,hJPAV0K"
},
{ { 0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8,
0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39,
0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67,
0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1 }, 32,
"k0oahJtB4gb5AbykM4DY5MKPknFZ,HyZ2ze7Unx2GEM"
},
{ { 0x00, }, 1,
"AA"
},
{ { 0x01, }, 1,
"BA"
},
{ { 0x01, 0x02 }, 2,
"BIA"
},
{ { 0x01, 0x02, 0x03 }, 3,
"BIwA"
},
{ { 0x01, 0x02, 0x03, 0x04 }, 4,
"BIwAEA"
},
{ { 0x01, 0x02, 0x03, 0x04, 0xff }, 5,
"BIwAE8P"
},
{ { 0x01, 0x02, 0x03, 0x04, 0xff, 0xfe }, 6,
"BIwAE8v,"
},
{ { 0x01, 0x02, 0x03, 0x04, 0xff, 0xfe, 0xfd }, 7,
"BIwAE8v,9D"
},
};
int main(int argc, char **argv)
{
int i, ret, len;
int errors = 0;
char tmp[1024], tmp2[1024];
if (argc == 3 && !strcmp(argv[1], "encode")) {
memset(tmp, 0, sizeof(tmp));
ext2fs_digest_encode(argv[2], strlen(argv[2]), tmp);
puts(tmp);
exit(0);
}
if (argc == 3 && !strcmp(argv[1], "decode")) {
memset(tmp, 0, sizeof(tmp));
ret = ext2fs_digest_decode(argv[2], strlen(argv[2]), tmp);
puts(tmp);
fprintf(stderr, "returned %d\n", ret);
exit(0);
}
for (i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) {
memset(tmp, 0, sizeof(tmp));
ret = ext2fs_digest_encode((const char *) tests[i].d,
tests[i].len, tmp);
len = strlen(tmp);
printf("Test Digest %d (returned %d): ", i, ret);
if (ret != len) {
printf("FAILED returned %d, string length was %d\n",
ret, len);
errors++;
continue;
} else if (strcmp(tmp, tests[i].ed) != 0) {
printf("FAILED: got %s, expected %s\n", tmp,
tests[i].ed);
errors++;
continue;
}
ret = ext2fs_digest_decode(tmp, len, tmp2);
if (ret != tests[i].len) {
printf("FAILED decode returned %d, expected %d\n",
ret, tests[i].len);
errors++;
continue;
}
if (memcmp(tmp2, tests[i].d, ret) != 0) {
puts("FAILED: decode mismatched");
errors++;
continue;
}
printf("OK\n");
}
for (i = 1; i < argc; i++) {
memset(tmp, 0, sizeof(tmp));
ret = ext2fs_digest_encode(argv[i], strlen(argv[i]), tmp);
len = strlen(tmp);
printf("Digest of '%s' is '%s' (returned %d, length %d)\n",
argv[i], tmp, ret, len);
}
return errors;
}
#endif /* UNITTEST */
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