1 /* $OpenBSD: base64.c,v 1.8 2015/01/16 16:48:51 deraadt 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 #include <sys/types.h>
46 #include <sys/socket.h>
47 #include <netinet/in.h>
48 #include <arpa/inet.h>
49 #include <arpa/nameser.h>
50
51 #include <ctype.h>
52 #include <resolv.h>
53 #include <stdio.h>
54
55 #include <stdlib.h>
56 #include <string.h>
57
58 static const char Base64[] =
59 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
60 static const char Pad64 = '=';
61
62 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
63 The following encoding technique is taken from RFC 1521 by Borenstein
64 and Freed. It is reproduced here in a slightly edited form for
65 convenience.
66
67 A 65-character subset of US-ASCII is used, enabling 6 bits to be
68 represented per printable character. (The extra 65th character, "=",
69 is used to signify a special processing function.)
70
71 The encoding process represents 24-bit groups of input bits as output
72 strings of 4 encoded characters. Proceeding from left to right, a
73 24-bit input group is formed by concatenating 3 8-bit input groups.
74 These 24 bits are then treated as 4 concatenated 6-bit groups, each
75 of which is translated into a single digit in the base64 alphabet.
76
77 Each 6-bit group is used as an index into an array of 64 printable
78 characters. The character referenced by the index is placed in the
79 output string.
80
81 Table 1: The Base64 Alphabet
82
83 Value Encoding Value Encoding Value Encoding Value Encoding
84 0 A 17 R 34 i 51 z
85 1 B 18 S 35 j 52 0
86 2 C 19 T 36 k 53 1
87 3 D 20 U 37 l 54 2
88 4 E 21 V 38 m 55 3
89 5 F 22 W 39 n 56 4
90 6 G 23 X 40 o 57 5
91 7 H 24 Y 41 p 58 6
92 8 I 25 Z 42 q 59 7
93 9 J 26 a 43 r 60 8
94 10 K 27 b 44 s 61 9
95 11 L 28 c 45 t 62 +
96 12 M 29 d 46 u 63 /
97 13 N 30 e 47 v
98 14 O 31 f 48 w (pad) =
99 15 P 32 g 49 x
100 16 Q 33 h 50 y
101
102 Special processing is performed if fewer than 24 bits are available
103 at the end of the data being encoded. A full encoding quantum is
104 always completed at the end of a quantity. When fewer than 24 input
105 bits are available in an input group, zero bits are added (on the
106 right) to form an integral number of 6-bit groups. Padding at the
107 end of the data is performed using the '=' character.
108
109 Since all base64 input is an integral number of octets, only the
110 -------------------------------------------------
111 following cases can arise:
112
113 (1) the final quantum of encoding input is an integral
114 multiple of 24 bits; here, the final unit of encoded
115 output will be an integral multiple of 4 characters
116 with no "=" padding,
117 (2) the final quantum of encoding input is exactly 8 bits;
118 here, the final unit of encoded output will be two
119 characters followed by two "=" padding characters, or
120 (3) the final quantum of encoding input is exactly 16 bits;
121 here, the final unit of encoded output will be three
122 characters followed by one "=" padding character.
123 */
124
125 int
b64_ntop(src,srclength,target,targsize)126 b64_ntop(src, srclength, target, targsize)
127 u_char const *src;
128 size_t srclength;
129 char *target;
130 size_t targsize;
131 {
132 size_t datalength = 0;
133 u_char input[3];
134 u_char output[4];
135 int i;
136
137 while (2 < srclength) {
138 input[0] = *src++;
139 input[1] = *src++;
140 input[2] = *src++;
141 srclength -= 3;
142
143 output[0] = input[0] >> 2;
144 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
145 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
146 output[3] = input[2] & 0x3f;
147
148 if (datalength + 4 > targsize)
149 return (-1);
150 target[datalength++] = Base64[output[0]];
151 target[datalength++] = Base64[output[1]];
152 target[datalength++] = Base64[output[2]];
153 target[datalength++] = Base64[output[3]];
154 }
155
156 /* Now we worry about padding. */
157 if (0 != srclength) {
158 /* Get what's left. */
159 input[0] = input[1] = input[2] = '\0';
160 for (i = 0; i < srclength; i++)
161 input[i] = *src++;
162
163 output[0] = input[0] >> 2;
164 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
165 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
166
167 if (datalength + 4 > targsize)
168 return (-1);
169 target[datalength++] = Base64[output[0]];
170 target[datalength++] = Base64[output[1]];
171 if (srclength == 1)
172 target[datalength++] = Pad64;
173 else
174 target[datalength++] = Base64[output[2]];
175 target[datalength++] = Pad64;
176 }
177 if (datalength >= targsize)
178 return (-1);
179 target[datalength] = '\0'; /* Returned value doesn't count \0. */
180 return (datalength);
181 }
182
183 /* skips all whitespace anywhere.
184 converts characters, four at a time, starting at (or after)
185 src from base - 64 numbers into three 8 bit bytes in the target area.
186 it returns the number of data bytes stored at the target, or -1 on error.
187 */
188
189 int
b64_pton(src,target,targsize)190 b64_pton(src, target, targsize)
191 char const *src;
192 u_char *target;
193 size_t targsize;
194 {
195 int tarindex, state, ch;
196 u_char nextbyte;
197 char *pos;
198
199 state = 0;
200 tarindex = 0;
201
202 while ((ch = (unsigned char)*src++) != '\0') {
203 if (isspace(ch)) /* Skip whitespace anywhere. */
204 continue;
205
206 if (ch == Pad64)
207 break;
208
209 pos = strchr(Base64, ch);
210 if (pos == 0) /* A non-base64 character. */
211 return (-1);
212
213 switch (state) {
214 case 0:
215 if (target) {
216 if (tarindex >= targsize)
217 return (-1);
218 target[tarindex] = (pos - Base64) << 2;
219 }
220 state = 1;
221 break;
222 case 1:
223 if (target) {
224 if (tarindex >= targsize)
225 return (-1);
226 target[tarindex] |= (pos - Base64) >> 4;
227 nextbyte = ((pos - Base64) & 0x0f) << 4;
228 if (tarindex + 1 < targsize)
229 target[tarindex+1] = nextbyte;
230 else if (nextbyte)
231 return (-1);
232 }
233 tarindex++;
234 state = 2;
235 break;
236 case 2:
237 if (target) {
238 if (tarindex >= targsize)
239 return (-1);
240 target[tarindex] |= (pos - Base64) >> 2;
241 nextbyte = ((pos - Base64) & 0x03) << 6;
242 if (tarindex + 1 < targsize)
243 target[tarindex+1] = nextbyte;
244 else if (nextbyte)
245 return (-1);
246 }
247 tarindex++;
248 state = 3;
249 break;
250 case 3:
251 if (target) {
252 if (tarindex >= targsize)
253 return (-1);
254 target[tarindex] |= (pos - Base64);
255 }
256 tarindex++;
257 state = 0;
258 break;
259 }
260 }
261
262 /*
263 * We are done decoding Base-64 chars. Let's see if we ended
264 * on a byte boundary, and/or with erroneous trailing characters.
265 */
266
267 if (ch == Pad64) { /* We got a pad char. */
268 ch = (unsigned char)*src++; /* Skip it, get next. */
269 switch (state) {
270 case 0: /* Invalid = in first position */
271 case 1: /* Invalid = in second position */
272 return (-1);
273
274 case 2: /* Valid, means one byte of info */
275 /* Skip any number of spaces. */
276 for (; ch != '\0'; ch = (unsigned char)*src++)
277 if (!isspace(ch))
278 break;
279 /* Make sure there is another trailing = sign. */
280 if (ch != Pad64)
281 return (-1);
282 ch = (unsigned char)*src++; /* Skip the = */
283 /* Fall through to "single trailing =" case. */
284 /* FALLTHROUGH */
285
286 case 3: /* Valid, means two bytes of info */
287 /*
288 * We know this char is an =. Is there anything but
289 * whitespace after it?
290 */
291 for (; ch != '\0'; ch = (unsigned char)*src++)
292 if (!isspace(ch))
293 return (-1);
294
295 /*
296 * Now make sure for cases 2 and 3 that the "extra"
297 * bits that slopped past the last full byte were
298 * zeros. If we don't check them, they become a
299 * subliminal channel.
300 */
301 if (target && tarindex < targsize &&
302 target[tarindex] != 0)
303 return (-1);
304 }
305 } else {
306 /*
307 * We ended by seeing the end of the string. Make sure we
308 * have no partial bytes lying around.
309 */
310 if (state != 0)
311 return (-1);
312 }
313
314 return (tarindex);
315 }
316