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Diffstat (limited to 'lib/ext2fs/digest_encode.c')
| -rw-r--r-- | lib/ext2fs/digest_encode.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/lib/ext2fs/digest_encode.c b/lib/ext2fs/digest_encode.c new file mode 100644 index 0000000..075963f --- /dev/null +++ b/lib/ext2fs/digest_encode.c @@ -0,0 +1,187 @@ +/* + * 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 */ |