1/*
2 * lib/ext2fs/digest_encode.c
3 *
4 * A function to encode a digest using 64 characters that are valid in a
5 * filename per ext2fs rules.
6 *
7 * Written by Uday Savagaonkar, 2014.
8 *
9 * Copyright 2014 Google Inc.  All Rights Reserved.
10 *
11 * %Begin-Header%
12 * This file may be redistributed under the terms of the GNU Library
13 * General Public License, version 2.
14 * %End-Header%
15 */
16
17#include "config.h"
18#if HAVE_SYS_TYPES_H
19#include <sys/types.h>
20#endif
21#include "ext2fs.h"
22
23static const char *lookup_table =
24	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
25
26/**
27 * ext2fs_digest_encode() -
28 *
29 * Encodes the input digest using characters from the set [a-zA-Z0-9_+].
30 * The encoded string is roughly 4/3 times the size of the input string.
31 */
32int ext2fs_digest_encode(const char *src, int len, char *dst)
33{
34	int i = 0, bits = 0, ac = 0;
35	char *cp = dst;
36
37	while (i < len) {
38		ac += (((unsigned char) src[i]) << bits);
39		bits += 8;
40		do {
41			*cp++ = lookup_table[ac & 0x3f];
42			ac >>= 6;
43			bits -= 6;
44		} while (bits >= 6);
45		i++;
46	}
47	if (bits)
48		*cp++ = lookup_table[ac & 0x3f];
49	return cp - dst;
50}
51
52int ext2fs_digest_decode(const char *src, int len, char *dst)
53{
54	int i = 0, bits = 0, ac = 0;
55	const char *p;
56	char *cp = dst;
57
58	while (i < len) {
59		p = strchr(lookup_table, src[i]);
60		if (p == NULL || src[i] == 0)
61			return -1;
62		ac += (p - lookup_table) << bits;
63		bits += 6;
64		if (bits >= 8) {
65			*cp++ = ac & 0xff;
66			ac >>= 8;
67			bits -= 8;
68		}
69		i++;
70	}
71	if (ac)
72		return -1;
73	return cp - dst;
74}
75
76
77#ifdef UNITTEST
78static const struct {
79	unsigned char d[32];
80	unsigned int len;
81	const unsigned char *ed;
82} tests[] = {
83	{ { 0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14,
84	    0x9a, 0xfb, 0xf4, 0xc8, 0x99, 0x6f, 0xb9, 0x24,
85	    0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b, 0x93, 0x4c,
86	    0xa4, 0x95, 0x99, 0x1b, 0x78, 0x52, 0xb8, 0x55 }, 32,
87	"jDLxChJ,cQhm7TPyZ+WukcirBROZbOJTkWZmbgnU4WF"
88	},
89	{ { 0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
90	    0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
91	    0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
92	    0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad }, 32,
93	"6inF,+YAPreQBBk3d5qIjA7AhNqlXoHn0Cx,hJPAV0K"
94	},
95	{ { 0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8,
96	    0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39,
97	    0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67,
98	    0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1 }, 32,
99	"k0oahJtB4gb5AbykM4DY5MKPknFZ,HyZ2ze7Unx2GEM"
100	},
101	{ { 0x00, }, 1,
102	"AA"
103	},
104	{ { 0x01, }, 1,
105	"BA"
106	},
107	{ { 0x01, 0x02 }, 2,
108	"BIA"
109	},
110	{ { 0x01, 0x02, 0x03 }, 3,
111	"BIwA"
112	},
113	{ { 0x01, 0x02, 0x03, 0x04 }, 4,
114	"BIwAEA"
115	},
116	{ { 0x01, 0x02, 0x03, 0x04, 0xff }, 5,
117	"BIwAE8P"
118	},
119	{ { 0x01, 0x02, 0x03, 0x04, 0xff, 0xfe }, 6,
120	"BIwAE8v,"
121	},
122	{ { 0x01, 0x02, 0x03, 0x04, 0xff, 0xfe, 0xfd }, 7,
123	"BIwAE8v,9D"
124	},
125};
126
127int main(int argc, char **argv)
128{
129	int i, ret, len, len2;
130	int errors = 0;
131	unsigned char tmp[1024], tmp2[1024];
132
133	if (argc == 3 && !strcmp(argv[1], "encode")) {
134		memset(tmp, 0, sizeof(tmp));
135		ext2fs_digest_encode(argv[2], strlen(argv[2]), tmp);
136		puts(tmp);
137		exit(0);
138	}
139	if (argc == 3 && !strcmp(argv[1], "decode")) {
140		memset(tmp, 0, sizeof(tmp));
141		ret = ext2fs_digest_decode(argv[2], strlen(argv[2]), tmp);
142		puts(tmp);
143		fprintf(stderr, "returned %d\n", ret);
144		exit(0);
145	}
146	for (i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) {
147		memset(tmp, 0, sizeof(tmp));
148		ret = ext2fs_digest_encode(tests[i].d, tests[i].len, tmp);
149		len = strlen(tmp);
150		printf("Test Digest %d (returned %d): ", i, ret);
151		if (ret != len) {
152			printf("FAILED returned %d, string length was %d\n",
153			       ret, len);
154			errors++;
155			continue;
156		} else if (strcmp(tmp, tests[i].ed) != 0) {
157			printf("FAILED: got %s, expected %s\n", tmp,
158			       tests[i].ed);
159			errors++;
160			continue;
161		}
162		ret = ext2fs_digest_decode(tmp, len, tmp2);
163		if (ret != tests[i].len) {
164			printf("FAILED decode returned %d, expected %d\n",
165			       ret, tests[i].len);
166			errors++;
167			continue;
168		}
169		if (memcmp(tmp2, tests[i].d, ret) != 0) {
170			puts("FAILED: decode mismatched");
171			errors++;
172			continue;
173		}
174		printf("OK\n");
175	}
176	for (i = 1; i < argc; i++) {
177		memset(tmp, 0, sizeof(tmp));
178		ret = ext2fs_digest_encode(argv[i], strlen(argv[i]), tmp);
179		len = strlen(tmp);
180		printf("Digest of '%s' is '%s' (returned %d, length %d)\n",
181		       argv[i], tmp, ret, len);
182	}
183	return errors;
184}
185
186#endif /* UNITTEST */
187