1/* $OpenBSD: base64.c,v 1.5 2006/10/21 09:55:03 otto Exp $ */
2
3/*
4 * Copyright (c) 1996 by Internet Software Consortium.
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
11 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
12 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
13 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
14 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
15 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
16 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
17 * SOFTWARE.
18 */
19
20/*
21 * Portions Copyright (c) 1995 by International Business Machines, Inc.
22 *
23 * International Business Machines, Inc. (hereinafter called IBM) grants
24 * permission under its copyrights to use, copy, modify, and distribute this
25 * Software with or without fee, provided that the above copyright notice and
26 * all paragraphs of this notice appear in all copies, and that the name of IBM
27 * not be used in connection with the marketing of any product incorporating
28 * the Software or modifications thereof, without specific, written prior
29 * permission.
30 *
31 * To the extent it has a right to do so, IBM grants an immunity from suit
32 * under its patents, if any, for the use, sale or manufacture of products to
33 * the extent that such products are used for performing Domain Name System
34 * dynamic updates in TCP/IP networks by means of the Software. No immunity is
35 * granted for any product per se or for any other function of any product.
36 *
37 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
38 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
39 * PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
40 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
41 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
42 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
43 */
44
45/* OPENBSD ORIGINAL: lib/libc/net/base64.c */
46
47#include "defs"
48
49#if (!defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP)) || (!defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON))
50
51#include <sys/types.h>
52#include <ctype.h>
53
54#include <byte.h>
55#include "base64.h"
56
57static const char Base64[] =
58 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
59static const char Pad64 = '=';
60
61/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
62 The following encoding technique is taken from RFC 1521 by Borenstein
63 and Freed. It is reproduced here in a slightly edited form for
64 convenience.
65
66 A 65-character subset of US-ASCII is used, enabling 6 bits to be
67 represented per printable character. (The extra 65th character, "=",
68 is used to signify a special processing function.)
69
70 The encoding process represents 24-bit groups of input bits as output
71 strings of 4 encoded characters. Proceeding from left to right, a
72 24-bit input group is formed by concatenating 3 8-bit input groups.
73 These 24 bits are then treated as 4 concatenated 6-bit groups, each
74 of which is translated into a single digit in the base64 alphabet.
75
76 Each 6-bit group is used as an index into an array of 64 printable
77 characters. The character referenced by the index is placed in the
78 output string.
79
80 Table 1: The Base64 Alphabet
81
82 Value Encoding Value Encoding Value Encoding Value Encoding
83 0 A 17 R 34 i 51 z
84 1 B 18 S 35 j 52 0
85 2 C 19 T 36 k 53 1
86 3 D 20 U 37 l 54 2
87 4 E 21 V 38 m 55 3
88 5 F 22 W 39 n 56 4
89 6 G 23 X 40 o 57 5
90 7 H 24 Y 41 p 58 6
91 8 I 25 Z 42 q 59 7
92 9 J 26 a 43 r 60 8
93 10 K 27 b 44 s 61 9
94 11 L 28 c 45 t 62 +
95 12 M 29 d 46 u 63 /
96 13 N 30 e 47 v
97 14 O 31 f 48 w (pad) =
98 15 P 32 g 49 x
99 16 Q 33 h 50 y
100
101 Special processing is performed if fewer than 24 bits are available
102 at the end of the data being encoded. A full encoding quantum is
103 always completed at the end of a quantity. When fewer than 24 input
104 bits are available in an input group, zero bits are added (on the
105 right) to form an integral number of 6-bit groups. Padding at the
106 end of the data is performed using the '=' character.
107
108 Since all base64 input is an integral number of octets, only the
109 -------------------------------------------------
110 following cases can arise:
111
112 (1) the final quantum of encoding input is an integral
113 multiple of 24 bits; here, the final unit of encoded
114 output will be an integral multiple of 4 characters
115 with no "=" padding,
116 (2) the final quantum of encoding input is exactly 8 bits;
117 here, the final unit of encoded output will be two
118 characters followed by two "=" padding characters, or
119 (3) the final quantum of encoding input is exactly 16 bits;
120 here, the final unit of encoded output will be three
121 characters followed by one "=" padding character.
122 */
123
124#if !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP)
125int
126b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize)
127{
128 size_t datalength = 0;
129 u_char input[3];
130 u_char output[4];
131 u_int i;
132
133 while (2 < srclength) {
134 input[0] = *src++;
135 input[1] = *src++;
136 input[2] = *src++;
137 srclength -= 3;
138
139 output[0] = input[0] >> 2;
140 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
141 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
142 output[3] = input[2] & 0x3f;
143
144 if (datalength + 4 > targsize)
145 return (-1);
146 target[datalength++] = Base64[output[0]];
147 target[datalength++] = Base64[output[1]];
148 target[datalength++] = Base64[output[2]];
149 target[datalength++] = Base64[output[3]];
150 }
151
152 /* Now we worry about padding. */
153 if (0 != srclength) {
154 /* Get what's left. */
155 input[0] = input[1] = input[2] = '\0';
156 for (i = 0; i < srclength; i++)
157 input[i] = *src++;
158
159 output[0] = input[0] >> 2;
160 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
161 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
162
163 if (datalength + 4 > targsize)
164 return (-1);
165 target[datalength++] = Base64[output[0]];
166 target[datalength++] = Base64[output[1]];
167 if (srclength == 1)
168 target[datalength++] = Pad64;
169 else
170 target[datalength++] = Base64[output[2]];
171 target[datalength++] = Pad64;
172 }
173 if (datalength >= targsize)
174 return (-1);
175 target[datalength] = '\0'; /* Returned value doesn't count \0. */
176 return (datalength);
177}
178#endif /* !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) */
179
180#if !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON)
181
182/* skips all whitespace anywhere.
183 converts characters, four at a time, starting at (or after)
184 src from base - 64 numbers into three 8 bit bytes in the target area.
185 it returns the number of data bytes stored at the target, or -1 on error.
186 */
187
188int
189b64_pton(char const *src, u_char *target, size_t targsize)
190{
191 u_int tarindex, state;
192 int ch;
193 size_t pos;
194
195 state = 0;
196 tarindex = 0;
197
198 while ((ch = *src++) != '\0') {
199 if (isspace(ch)) /* Skip whitespace anywhere. */
200 continue;
201
202 if (ch == Pad64)
203 break;
204
205 pos = byte_chr(Base64, 64, ch);
206 if (pos >= 64) /* A non-base64 character. */
207 return (-1);
208
209 switch (state) {
210 case 0:
211 if (target) {
212 if (tarindex >= targsize)
213 return (-1);
214 target[tarindex] = pos << 2;
215 }
216 state = 1;
217 break;
218 case 1:
219 if (target) {
220 if (tarindex + 1 >= targsize)
221 return (-1);
222 target[tarindex] |= pos >> 4;
223 target[tarindex+1] = (pos & 0x0f)
224 << 4 ;
225 }
226 tarindex++;
227 state = 2;
228 break;
229 case 2:
230 if (target) {
231 if (tarindex + 1 >= targsize)
232 return (-1);
233 target[tarindex] |= pos >> 2;
234 target[tarindex+1] = (pos & 0x03)
235 << 6;
236 }
237 tarindex++;
238 state = 3;
239 break;
240 case 3:
241 if (target) {
242 if (tarindex >= targsize)
243 return (-1);
244 target[tarindex] |= pos;
245 }
246 tarindex++;
247 state = 0;
248 break;
249 }
250 }
251
252 /*
253 * We are done decoding Base-64 chars. Let's see if we ended
254 * on a byte boundary, and/or with erroneous trailing characters.
255 */
256
257 if (ch == Pad64) { /* We got a pad char. */
258 ch = *src++; /* Skip it, get next. */
259 switch (state) {
260 case 0: /* Invalid = in first position */
261 case 1: /* Invalid = in second position */
262 return (-1);
263
264 case 2: /* Valid, means one byte of info */
265 /* Skip any number of spaces. */
266 for (; ch != '\0'; ch = *src++)
267 if (!isspace(ch))
268 break;
269 /* Make sure there is another trailing = sign. */
270 if (ch != Pad64)
271 return (-1);
272 ch = *src++; /* Skip the = */
273 /* Fall through to "single trailing =" case. */
274 /* FALLTHROUGH */
275
276 case 3: /* Valid, means two bytes of info */
277 /*
278 * We know this char is an =. Is there anything but
279 * whitespace after it?
280 */
281 for (; ch != '\0'; ch = *src++)
282 if (!isspace(ch))
283 return (-1);
284
285 /*
286 * Now make sure for cases 2 and 3 that the "extra"
287 * bits that slopped past the last full byte were
288 * zeros. If we don't check them, they become a
289 * subliminal channel.
290 */
291 if (target && target[tarindex] != 0)
292 return (-1);
293 }
294 } else {
295 /*
296 * We ended by seeing the end of the string. Make sure we
297 * have no partial bytes lying around.
298 */
299 if (state != 0)
300 return (-1);
301 }
302
303 return (tarindex);
304}
305
306#endif /* !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON) */
307#endif
