1 /* $OpenBSD: base64.c,v 1.4 2002/01/02 23:00:10 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 #pragma ident "%Z%%M% %I% %E% SMI"
46
47 #include "includes.h"
48
49 #if !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP)
50
51 #include <sys/types.h>
52 #include <sys/param.h>
53 #include <sys/socket.h>
54 #include <netinet/in.h>
55 #include <arpa/inet.h>
56
57 #include <ctype.h>
58 #include <stdio.h>
59
60 #include <stdlib.h>
61 #include <string.h>
62
63 #include "base64.h"
64
65 /* XXX abort illegal in library */
66 #define Assert(Cond) if (!(Cond)) abort()
67
68 static const char Base64[] =
69 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
70 static const char Pad64 = '=';
71
72 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
73 The following encoding technique is taken from RFC 1521 by Borenstein
74 and Freed. It is reproduced here in a slightly edited form for
75 convenience.
76
77 A 65-character subset of US-ASCII is used, enabling 6 bits to be
78 represented per printable character. (The extra 65th character, "=",
79 is used to signify a special processing function.)
80
81 The encoding process represents 24-bit groups of input bits as output
82 strings of 4 encoded characters. Proceeding from left to right, a
83 24-bit input group is formed by concatenating 3 8-bit input groups.
84 These 24 bits are then treated as 4 concatenated 6-bit groups, each
85 of which is translated into a single digit in the base64 alphabet.
86
87 Each 6-bit group is used as an index into an array of 64 printable
88 characters. The character referenced by the index is placed in the
89 output string.
90
91 Table 1: The Base64 Alphabet
92
93 Value Encoding Value Encoding Value Encoding Value Encoding
94 0 A 17 R 34 i 51 z
95 1 B 18 S 35 j 52 0
96 2 C 19 T 36 k 53 1
97 3 D 20 U 37 l 54 2
98 4 E 21 V 38 m 55 3
99 5 F 22 W 39 n 56 4
100 6 G 23 X 40 o 57 5
101 7 H 24 Y 41 p 58 6
102 8 I 25 Z 42 q 59 7
103 9 J 26 a 43 r 60 8
104 10 K 27 b 44 s 61 9
105 11 L 28 c 45 t 62 +
106 12 M 29 d 46 u 63 /
107 13 N 30 e 47 v
108 14 O 31 f 48 w (pad) =
109 15 P 32 g 49 x
110 16 Q 33 h 50 y
111
112 Special processing is performed if fewer than 24 bits are available
113 at the end of the data being encoded. A full encoding quantum is
114 always completed at the end of a quantity. When fewer than 24 input
115 bits are available in an input group, zero bits are added (on the
116 right) to form an integral number of 6-bit groups. Padding at the
117 end of the data is performed using the '=' character.
118
119 Since all base64 input is an integral number of octets, only the
120 -------------------------------------------------
121 following cases can arise:
122
123 (1) the final quantum of encoding input is an integral
124 multiple of 24 bits; here, the final unit of encoded
125 output will be an integral multiple of 4 characters
126 with no "=" padding,
127 (2) the final quantum of encoding input is exactly 8 bits;
128 here, the final unit of encoded output will be two
129 characters followed by two "=" padding characters, or
130 (3) the final quantum of encoding input is exactly 16 bits;
131 here, the final unit of encoded output will be three
132 characters followed by one "=" padding character.
133 */
134
135 int
136 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize)
137 {
138 size_t datalength = 0;
139 u_char input[3];
140 u_char output[4];
141 int i;
142
143 while (2 < srclength) {
144 input[0] = *src++;
145 input[1] = *src++;
146 input[2] = *src++;
147 srclength -= 3;
148
149 output[0] = input[0] >> 2;
150 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
151 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
152 output[3] = input[2] & 0x3f;
153 Assert(output[0] < 64);
154 Assert(output[1] < 64);
155 Assert(output[2] < 64);
156 Assert(output[3] < 64);
157
158 if (datalength + 4 > targsize)
159 return (-1);
160 target[datalength++] = Base64[output[0]];
161 target[datalength++] = Base64[output[1]];
162 target[datalength++] = Base64[output[2]];
163 target[datalength++] = Base64[output[3]];
164 }
165
166 /* Now we worry about padding. */
167 if (0 != srclength) {
168 /* Get what's left. */
169 input[0] = input[1] = input[2] = '\0';
170 for (i = 0; i < srclength; i++)
171 input[i] = *src++;
172
173 output[0] = input[0] >> 2;
174 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
175 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
176 Assert(output[0] < 64);
177 Assert(output[1] < 64);
178 Assert(output[2] < 64);
179
180 if (datalength + 4 > targsize)
181 return (-1);
182 target[datalength++] = Base64[output[0]];
183 target[datalength++] = Base64[output[1]];
184 if (srclength == 1)
185 target[datalength++] = Pad64;
186 else
187 target[datalength++] = Base64[output[2]];
188 target[datalength++] = Pad64;
189 }
190 if (datalength >= targsize)
191 return (-1);
192 target[datalength] = '\0'; /* Returned value doesn't count \0. */
193 return (datalength);
194 }
195
196 /* skips all whitespace anywhere.
197 converts characters, four at a time, starting at (or after)
198 src from base - 64 numbers into three 8 bit bytes in the target area.
199 it returns the number of data bytes stored at the target, or -1 on error.
200 */
201
202 int
203 b64_pton(u_char const *src, u_char *target, size_t targsize)
204 {
205 int tarindex, state, ch;
206 char *pos;
207
208 state = 0;
209 tarindex = 0;
210
211 while ((ch = *src++) != '\0') {
212 if (isspace(ch)) /* Skip whitespace anywhere. */
213 continue;
214
215 if (ch == Pad64)
216 break;
217
218 pos = strchr(Base64, ch);
219 if (pos == 0) /* A non-base64 character. */
220 return (-1);
221
222 switch (state) {
223 case 0:
224 if (target) {
225 if (tarindex >= targsize)
226 return (-1);
227 target[tarindex] = (pos - Base64) << 2;
228 }
229 state = 1;
230 break;
231 case 1:
232 if (target) {
233 if (tarindex + 1 >= targsize)
234 return (-1);
235 target[tarindex] |= (pos - Base64) >> 4;
236 target[tarindex+1] = ((pos - Base64) & 0x0f)
237 << 4 ;
238 }
239 tarindex++;
240 state = 2;
241 break;
242 case 2:
243 if (target) {
244 if (tarindex + 1 >= targsize)
245 return (-1);
246 target[tarindex] |= (pos - Base64) >> 2;
247 target[tarindex+1] = ((pos - Base64) & 0x03)
248 << 6;
249 }
250 tarindex++;
251 state = 3;
252 break;
253 case 3:
254 if (target) {
255 if (tarindex >= targsize)
256 return (-1);
257 target[tarindex] |= (pos - Base64);
258 }
259 tarindex++;
260 state = 0;
261 break;
262 }
263 }
264
265 /*
266 * We are done decoding Base-64 chars. Let's see if we ended
267 * on a byte boundary, and/or with erroneous trailing characters.
268 */
269
270 if (ch == Pad64) { /* We got a pad char. */
271 ch = *src++; /* Skip it, get next. */
272 switch (state) {
273 case 0: /* Invalid = in first position */
274 case 1: /* Invalid = in second position */
275 return (-1);
276
277 case 2: /* Valid, means one byte of info */
278 /* Skip any number of spaces. */
279 for (; ch != '\0'; ch = *src++)
280 if (!isspace(ch))
281 break;
282 /* Make sure there is another trailing = sign. */
283 if (ch != Pad64)
284 return (-1);
285 ch = *src++; /* Skip the = */
286 /* Fall through to "single trailing =" case. */
287 /* FALLTHROUGH */
288
289 case 3: /* Valid, means two bytes of info */
290 /*
291 * We know this char is an =. Is there anything but
292 * whitespace after it?
293 */
294 for (; ch != '\0'; ch = *src++)
295 if (!isspace(ch))
296 return (-1);
297
298 /*
299 * Now make sure for cases 2 and 3 that the "extra"
300 * bits that slopped past the last full byte were
301 * zeros. If we don't check them, they become a
302 * subliminal channel.
303 */
304 if (target && target[tarindex] != 0)
305 return (-1);
306 }
307 } else {
308 /*
309 * We ended by seeing the end of the string. Make sure we
310 * have no partial bytes lying around.
311 */
312 if (state != 0)
313 return (-1);
314 }
315
316 return (tarindex);
317 }
318
319 #endif /* !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) */