1 /* $NetBSD: base64.c,v 1.8 2002/11/11 01:15:17 thorpej Exp $ */
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 */
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 */
45 #include <sys/cdefs.h>
46 #if defined(LIBC_SCCS) && !defined(lint)
47 __RCSID("$NetBSD: base64.c,v 1.8 2002/11/11 01:15:17 thorpej Exp $");
48 #endif /* LIBC_SCCS and not lint */
50 #include <sys/types.h>
51 #include <sys/param.h>
52 #include <sys/socket.h>
53 #include <netinet/in.h>
54 #include <arpa/inet.h>
55 #include "arpa_nameser.h"
57 #include <assert.h>
58 #include <ctype.h>
59 #ifdef ANDROID_CHANGES
60 #include "resolv_private.h"
61 #else
62 #include <resolv.h>
63 #endif
64 #include <stdio.h>
66 #include <stdlib.h>
67 #include <string.h>
69 static const char Base64[] =
70 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
71 static const char Pad64 = '=';
73 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
74 The following encoding technique is taken from RFC 1521 by Borenstein
75 and Freed. It is reproduced here in a slightly edited form for
76 convenience.
78 A 65-character subset of US-ASCII is used, enabling 6 bits to be
79 represented per printable character. (The extra 65th character, "=",
80 is used to signify a special processing function.)
82 The encoding process represents 24-bit groups of input bits as output
83 strings of 4 encoded characters. Proceeding from left to right, a
84 24-bit input group is formed by concatenating 3 8-bit input groups.
85 These 24 bits are then treated as 4 concatenated 6-bit groups, each
86 of which is translated into a single digit in the base64 alphabet.
88 Each 6-bit group is used as an index into an array of 64 printable
89 characters. The character referenced by the index is placed in the
90 output string.
92 Table 1: The Base64 Alphabet
94 Value Encoding Value Encoding Value Encoding Value Encoding
95 0 A 17 R 34 i 51 z
96 1 B 18 S 35 j 52 0
97 2 C 19 T 36 k 53 1
98 3 D 20 U 37 l 54 2
99 4 E 21 V 38 m 55 3
100 5 F 22 W 39 n 56 4
101 6 G 23 X 40 o 57 5
102 7 H 24 Y 41 p 58 6
103 8 I 25 Z 42 q 59 7
104 9 J 26 a 43 r 60 8
105 10 K 27 b 44 s 61 9
106 11 L 28 c 45 t 62 +
107 12 M 29 d 46 u 63 /
108 13 N 30 e 47 v
109 14 O 31 f 48 w (pad) =
110 15 P 32 g 49 x
111 16 Q 33 h 50 y
113 Special processing is performed if fewer than 24 bits are available
114 at the end of the data being encoded. A full encoding quantum is
115 always completed at the end of a quantity. When fewer than 24 input
116 bits are available in an input group, zero bits are added (on the
117 right) to form an integral number of 6-bit groups. Padding at the
118 end of the data is performed using the '=' character.
120 Since all base64 input is an integral number of octets, only the
121 -------------------------------------------------
122 following cases can arise:
124 (1) the final quantum of encoding input is an integral
125 multiple of 24 bits; here, the final unit of encoded
126 output will be an integral multiple of 4 characters
127 with no "=" padding,
128 (2) the final quantum of encoding input is exactly 8 bits;
129 here, the final unit of encoded output will be two
130 characters followed by two "=" padding characters, or
131 (3) the final quantum of encoding input is exactly 16 bits;
132 here, the final unit of encoded output will be three
133 characters followed by one "=" padding character.
134 */
136 int
137 b64_ntop(src, srclength, target, targsize)
138 u_char const *src;
139 size_t srclength;
140 char *target;
141 size_t targsize;
142 {
143 size_t datalength = 0;
144 u_char input[3];
145 u_char output[4];
146 size_t i;
148 assert(src != NULL);
149 assert(target != NULL);
151 while (2 < srclength) {
152 input[0] = *src++;
153 input[1] = *src++;
154 input[2] = *src++;
155 srclength -= 3;
157 output[0] = (u_int32_t)input[0] >> 2;
158 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) +
159 ((u_int32_t)input[1] >> 4);
160 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) +
161 ((u_int32_t)input[2] >> 6);
162 output[3] = input[2] & 0x3f;
163 assert(output[0] < 64);
164 assert(output[1] < 64);
165 assert(output[2] < 64);
166 assert(output[3] < 64);
168 if (datalength + 4 > targsize)
169 return (-1);
170 target[datalength++] = Base64[output[0]];
171 target[datalength++] = Base64[output[1]];
172 target[datalength++] = Base64[output[2]];
173 target[datalength++] = Base64[output[3]];
174 }
176 /* Now we worry about padding. */
177 if (0 != srclength) {
178 /* Get what's left. */
179 input[0] = input[1] = input[2] = '\0';
180 for (i = 0; i < srclength; i++)
181 input[i] = *src++;
183 output[0] = (u_int32_t)input[0] >> 2;
184 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) +
185 ((u_int32_t)input[1] >> 4);
186 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) +
187 ((u_int32_t)input[2] >> 6);
188 assert(output[0] < 64);
189 assert(output[1] < 64);
190 assert(output[2] < 64);
192 if (datalength + 4 > targsize)
193 return (-1);
194 target[datalength++] = Base64[output[0]];
195 target[datalength++] = Base64[output[1]];
196 if (srclength == 1)
197 target[datalength++] = Pad64;
198 else
199 target[datalength++] = Base64[output[2]];
200 target[datalength++] = Pad64;
201 }
202 if (datalength >= targsize)
203 return (-1);
204 target[datalength] = '\0'; /* Returned value doesn't count \0. */
205 return (datalength);
206 }
208 /* skips all whitespace anywhere.
209 converts characters, four at a time, starting at (or after)
210 src from base - 64 numbers into three 8 bit bytes in the target area.
211 it returns the number of data bytes stored at the target, or -1 on error.
212 */
214 int
215 b64_pton(src, target, targsize)
216 char const *src;
217 u_char *target;
218 size_t targsize;
219 {
220 size_t tarindex;
221 int state, ch;
222 char *pos;
224 assert(src != NULL);
225 assert(target != NULL);
227 state = 0;
228 tarindex = 0;
230 while ((ch = (u_char) *src++) != '\0') {
231 if (isspace(ch)) /* Skip whitespace anywhere. */
232 continue;
234 if (ch == Pad64)
235 break;
237 pos = strchr(Base64, ch);
238 if (pos == 0) /* A non-base64 character. */
239 return (-1);
241 switch (state) {
242 case 0:
243 if (target) {
244 if (tarindex >= targsize)
245 return (-1);
246 target[tarindex] = (pos - Base64) << 2;
247 }
248 state = 1;
249 break;
250 case 1:
251 if (target) {
252 if (tarindex + 1 >= targsize)
253 return (-1);
254 target[tarindex] |=
255 (u_int32_t)(pos - Base64) >> 4;
256 target[tarindex+1] = ((pos - Base64) & 0x0f)
257 << 4 ;
258 }
259 tarindex++;
260 state = 2;
261 break;
262 case 2:
263 if (target) {
264 if (tarindex + 1 >= targsize)
265 return (-1);
266 target[tarindex] |=
267 (u_int32_t)(pos - Base64) >> 2;
268 target[tarindex+1] = ((pos - Base64) & 0x03)
269 << 6;
270 }
271 tarindex++;
272 state = 3;
273 break;
274 case 3:
275 if (target) {
276 if (tarindex >= targsize)
277 return (-1);
278 target[tarindex] |= (pos - Base64);
279 }
280 tarindex++;
281 state = 0;
282 break;
283 default:
284 abort();
285 }
286 }
288 /*
289 * We are done decoding Base-64 chars. Let's see if we ended
290 * on a byte boundary, and/or with erroneous trailing characters.
291 */
293 if (ch == Pad64) { /* We got a pad char. */
294 ch = *src++; /* Skip it, get next. */
295 switch (state) {
296 case 0: /* Invalid = in first position */
297 case 1: /* Invalid = in second position */
298 return (-1);
300 case 2: /* Valid, means one byte of info */
301 /* Skip any number of spaces. */
302 for (; ch != '\0'; ch = (u_char) *src++)
303 if (!isspace(ch))
304 break;
305 /* Make sure there is another trailing = sign. */
306 if (ch != Pad64)
307 return (-1);
308 ch = *src++; /* Skip the = */
309 /* Fall through to "single trailing =" case. */
310 /* FALLTHROUGH */
312 case 3: /* Valid, means two bytes of info */
313 /*
314 * We know this char is an =. Is there anything but
315 * whitespace after it?
316 */
317 for (; ch != '\0'; ch = (u_char) *src++)
318 if (!isspace(ch))
319 return (-1);
321 /*
322 * Now make sure for cases 2 and 3 that the "extra"
323 * bits that slopped past the last full byte were
324 * zeros. If we don't check them, they become a
325 * subliminal channel.
326 */
327 if (target && target[tarindex] != 0)
328 return (-1);
329 }
330 } else {
331 /*
332 * We ended by seeing the end of the string. Make sure we
333 * have no partial bytes lying around.
334 */
335 if (state != 0)
336 return (-1);
337 }
339 return (tarindex);
340 }