summaryrefslogtreecommitdiffstats
path: root/src/lib/base64.c
blob: 6b40866d0b17371f9db673edc5f2fda1dfa998af (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
/*
 * Copyright (C) 1999, 2000, 2001, 2004, 2005, 2006 Free Software
 * Foundation, Inc.
 *
 * This program is left software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/**
 * @brief Encode/decode binary data using printable characters.
 * @author Simon Josefsson.
 * @see RFC 3548 <http://www.ietf.org/rfc/rfc3548.txt>.
 */
RCSID("$Id$")

#include <freeradius-devel/libradius.h>
#include <freeradius-devel/base64.h>

#define us(x) (uint8_t) x

/** Base 64 encode binary data
 *
 * Base64 encode IN array of size INLEN into OUT array of size OUTLEN.
 *
 * @param[out] out Where to write Base64 string.
 * @param[in] outlen size of buffer including NULL byte.
 * @param[in] in Data to encode.
 * @param[in] inlen Length of data to encode.
 * @return The amount of data we wrote to the buffer or -1 if output buffer
 *	was too small.
 */
ssize_t fr_base64_encode(char *out, size_t outlen, uint8_t const *in, size_t inlen)
{
	static char const b64str[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

	char *p = out;
	if (outlen < (FR_BASE64_ENC_LENGTH(inlen) + 1)) {
		*out = '\0';
		return -1;
	}

	while (inlen) {
		*p++ = b64str[(in[0] >> 2) & 0x3f];
		*p++ = b64str[((in[0] << 4) + (--inlen ? in[1] >> 4 : 0)) & 0x3f];
		*p++ = (inlen ? b64str[((in[1] << 2) + (--inlen ? in[2] >> 6 : 0)) & 0x3f] : '=');
		*p++ = inlen ? b64str[in[2] & 0x3f] : '=';

		if (inlen) inlen--;
		if (inlen) in += 3;
	}

	p[0] = '\0';

	return p - out;
}

/*
 * With this approach this file works independent of the charset used
 * (think EBCDIC).  However, it does assume that the characters in the
 * Base64 alphabet (A-Za-z0-9+/) are encoded in 0..255.  POSIX
 * 1003.1-2001 require that char and unsigned char are 8-bit
 * quantities, though, taking care of that problem.  But this may be a
 * potential problem on non-POSIX C99 platforms.
 *
 * IBM C V6 for AIX mishandles "#define B64(x) ...'x'...", so use "_"
 * as the formal parameter rather than "x".
 */
#define B64(_)					\
  ((_) == 'A' ? 0				\
   : (_) == 'B' ? 1				\
   : (_) == 'C' ? 2				\
   : (_) == 'D' ? 3				\
   : (_) == 'E' ? 4				\
   : (_) == 'F' ? 5				\
   : (_) == 'G' ? 6				\
   : (_) == 'H' ? 7				\
   : (_) == 'I' ? 8				\
   : (_) == 'J' ? 9				\
   : (_) == 'K' ? 10				\
   : (_) == 'L' ? 11				\
   : (_) == 'M' ? 12				\
   : (_) == 'N' ? 13				\
   : (_) == 'O' ? 14				\
   : (_) == 'P' ? 15				\
   : (_) == 'Q' ? 16				\
   : (_) == 'R' ? 17				\
   : (_) == 'S' ? 18				\
   : (_) == 'T' ? 19				\
   : (_) == 'U' ? 20				\
   : (_) == 'V' ? 21				\
   : (_) == 'W' ? 22				\
   : (_) == 'X' ? 23				\
   : (_) == 'Y' ? 24				\
   : (_) == 'Z' ? 25				\
   : (_) == 'a' ? 26				\
   : (_) == 'b' ? 27				\
   : (_) == 'c' ? 28				\
   : (_) == 'd' ? 29				\
   : (_) == 'e' ? 30				\
   : (_) == 'f' ? 31				\
   : (_) == 'g' ? 32				\
   : (_) == 'h' ? 33				\
   : (_) == 'i' ? 34				\
   : (_) == 'j' ? 35				\
   : (_) == 'k' ? 36				\
   : (_) == 'l' ? 37				\
   : (_) == 'm' ? 38				\
   : (_) == 'n' ? 39				\
   : (_) == 'o' ? 40				\
   : (_) == 'p' ? 41				\
   : (_) == 'q' ? 42				\
   : (_) == 'r' ? 43				\
   : (_) == 's' ? 44				\
   : (_) == 't' ? 45				\
   : (_) == 'u' ? 46				\
   : (_) == 'v' ? 47				\
   : (_) == 'w' ? 48				\
   : (_) == 'x' ? 49				\
   : (_) == 'y' ? 50				\
   : (_) == 'z' ? 51				\
   : (_) == '0' ? 52				\
   : (_) == '1' ? 53				\
   : (_) == '2' ? 54				\
   : (_) == '3' ? 55				\
   : (_) == '4' ? 56				\
   : (_) == '5' ? 57				\
   : (_) == '6' ? 58				\
   : (_) == '7' ? 59				\
   : (_) == '8' ? 60				\
   : (_) == '9' ? 61				\
   : (_) == '+' ? 62				\
   : (_) == '/' ? 63				\
   : -1)

static const signed char b64[0x100] = {
  B64 (0), B64 (1), B64 (2), B64 (3),
  B64 (4), B64 (5), B64 (6), B64 (7),
  B64 (8), B64 (9), B64 (10), B64 (11),
  B64 (12), B64 (13), B64 (14), B64 (15),
  B64 (16), B64 (17), B64 (18), B64 (19),
  B64 (20), B64 (21), B64 (22), B64 (23),
  B64 (24), B64 (25), B64 (26), B64 (27),
  B64 (28), B64 (29), B64 (30), B64 (31),
  B64 (32), B64 (33), B64 (34), B64 (35),
  B64 (36), B64 (37), B64 (38), B64 (39),
  B64 (40), B64 (41), B64 (42), B64 (43),
  B64 (44), B64 (45), B64 (46), B64 (47),
  B64 (48), B64 (49), B64 (50), B64 (51),
  B64 (52), B64 (53), B64 (54), B64 (55),
  B64 (56), B64 (57), B64 (58), B64 (59),
  B64 (60), B64 (61), B64 (62), B64 (63),
  B64 (64), B64 (65), B64 (66), B64 (67),
  B64 (68), B64 (69), B64 (70), B64 (71),
  B64 (72), B64 (73), B64 (74), B64 (75),
  B64 (76), B64 (77), B64 (78), B64 (79),
  B64 (80), B64 (81), B64 (82), B64 (83),
  B64 (84), B64 (85), B64 (86), B64 (87),
  B64 (88), B64 (89), B64 (90), B64 (91),
  B64 (92), B64 (93), B64 (94), B64 (95),
  B64 (96), B64 (97), B64 (98), B64 (99),
  B64 (100), B64 (101), B64 (102), B64 (103),
  B64 (104), B64 (105), B64 (106), B64 (107),
  B64 (108), B64 (109), B64 (110), B64 (111),
  B64 (112), B64 (113), B64 (114), B64 (115),
  B64 (116), B64 (117), B64 (118), B64 (119),
  B64 (120), B64 (121), B64 (122), B64 (123),
  B64 (124), B64 (125), B64 (126), B64 (127),
  B64 (128), B64 (129), B64 (130), B64 (131),
  B64 (132), B64 (133), B64 (134), B64 (135),
  B64 (136), B64 (137), B64 (138), B64 (139),
  B64 (140), B64 (141), B64 (142), B64 (143),
  B64 (144), B64 (145), B64 (146), B64 (147),
  B64 (148), B64 (149), B64 (150), B64 (151),
  B64 (152), B64 (153), B64 (154), B64 (155),
  B64 (156), B64 (157), B64 (158), B64 (159),
  B64 (160), B64 (161), B64 (162), B64 (163),
  B64 (164), B64 (165), B64 (166), B64 (167),
  B64 (168), B64 (169), B64 (170), B64 (171),
  B64 (172), B64 (173), B64 (174), B64 (175),
  B64 (176), B64 (177), B64 (178), B64 (179),
  B64 (180), B64 (181), B64 (182), B64 (183),
  B64 (184), B64 (185), B64 (186), B64 (187),
  B64 (188), B64 (189), B64 (190), B64 (191),
  B64 (192), B64 (193), B64 (194), B64 (195),
  B64 (196), B64 (197), B64 (198), B64 (199),
  B64 (200), B64 (201), B64 (202), B64 (203),
  B64 (204), B64 (205), B64 (206), B64 (207),
  B64 (208), B64 (209), B64 (210), B64 (211),
  B64 (212), B64 (213), B64 (214), B64 (215),
  B64 (216), B64 (217), B64 (218), B64 (219),
  B64 (220), B64 (221), B64 (222), B64 (223),
  B64 (224), B64 (225), B64 (226), B64 (227),
  B64 (228), B64 (229), B64 (230), B64 (231),
  B64 (232), B64 (233), B64 (234), B64 (235),
  B64 (236), B64 (237), B64 (238), B64 (239),
  B64 (240), B64 (241), B64 (242), B64 (243),
  B64 (244), B64 (245), B64 (246), B64 (247),
  B64 (248), B64 (249), B64 (250), B64 (251),
  B64 (252), B64 (253), B64 (254), B64 (255)
};

/** Check if char is in Base64 alphabet
 *
 * Note that '=' is padding and not considered to be part of the alphabet.
 *
 * @param c char to check.
 * @return true if CH is a character from the Base64 alphabet, and false
 *	otherwise.
 */
bool fr_is_base64(char c)
{
	return b64[us(c)] >= 0;
}

/* Decode base64 encoded input array.
 *
 * Decode base64 encoded input array IN of length INLEN to output array OUT that
 * can hold *OUTLEN bytes.  Return true if decoding was successful, i.e.
 * if the input was valid base64 data, -1 otherwise.
 *
 * If *OUTLEN is too small, as many bytes as possible will be written to OUT.
 * On return, *OUTLEN holds the length of decoded bytes in OUT.
 *
 * Note that as soon as any non-alphabet characters are encountered,
 * decoding is stopped and -1 is returned.
 *
 * This means that, when applicable, you must remove any line terminators
 * that is part of the data stream before calling this function.
 *
 * @param[out] out Where to write the decoded data.
 * @param[in] outlen The length of the output buffer.
 * @param[in] in Base64 string to decode.
 * @param[in] inlen length of Base64 string.
 * @return -1 on error, else the length of decoded data.
 */
ssize_t fr_base64_decode(uint8_t *out, size_t outlen, char const *in, size_t inlen)
{
	uint8_t   *out_p = out;
	uint8_t   *out_end = out + outlen;
	char const  *p = in, *q;
	char const  *end = p + inlen;

	/*
	*  Process complete 24bit quanta
	*/
	while ((end - p) >= 4) {
		if (!fr_is_base64(p[0]) || !fr_is_base64(p[1]) || !fr_is_base64(p[2]) || !fr_is_base64(p[3])) break;

		/*
		*  Check we have enough bytes to write out
		*  the 24bit quantum.
		*/
		if ((out_end - out_p) <= 3) {
		oob:
			fr_strerror_printf("Output buffer too small, needed at least %zu bytes", outlen + 1);
			return p - end;
		}

		*out_p++ = ((b64[us(p[0])] << 2) | (b64[us(p[1])] >> 4));
		*out_p++ = ((b64[us(p[1])] << 4) & 0xf0) | (b64[us(p[2])] >> 2);
		*out_p++ = ((b64[us(p[2])] << 6) & 0xc0) | b64[us(p[3])];

		p += 4; /* 32bit input -> 24bit output */
	}

	q = p;

	/*
	*  Find the first non-base64 char
	*/
	while ((q < end) && fr_is_base64(*q)) q++;

	switch (q - p) {
	case 0:   /* Final quantum is 24 bits */
	break;

	case 2:   /* Final quantum is 8 bits */
		if ((out_end - out_p) < 1) goto oob;
		*out_p++ = ((b64[us(p[0])] << 2) | (b64[us(p[1])] >> 4));
		p += 2;
	break;

	case 3:   /* Final quantum is 16 bits */
		if ((out_end - out_p) < 2) goto oob;
		*out_p++ = ((b64[us(p[0])] << 2) | (b64[us(p[1])] >> 4));
		*out_p++ = ((b64[us(p[1])] << 4) & 0xf0) | (b64[us(p[2])] >> 2);
		p += 3;
	break;

	default:
		fr_strerror_printf("Invalid base64 padding data");
		return p - end;
	}

	while (p < end) {
		if (*p != '=') {
			fr_strerror_printf("Found non-padding char '%c' at end of base64 string", *p);
			return p - end;
		}
		p++;
	}

	return out_p - out;
}