1 /* $OpenBSD: base64.c,v 1.7 2013/12/31 02:32:56 tedu 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/param.h>
47 #include <sys/socket.h>
48 #include <netinet/in.h>
49 #include <arpa/inet.h>
50 #include <arpa/nameser.h>
51
52 #include <ctype.h>
53 #include <resolv.h>
54 #include <stdio.h>
55
56 #include <stdlib.h>
57 #include <string.h>
58
59 __RCSID("$MirOS: src/lib/libc/net/base64.c,v 1.4 2014/03/05 13:15:11 tg Exp $");
60
61 extern const uint8_t mbsd_digits_base64[65];
62 static const char Pad64 = '=';
63
64 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
65 The following encoding technique is taken from RFC 1521 by Borenstein
66 and Freed. It is reproduced here in a slightly edited form for
67 convenience.
68
69 A 65-character subset of US-ASCII is used, enabling 6 bits to be
70 represented per printable character. (The extra 65th character, "=",
71 is used to signify a special processing function.)
72
73 The encoding process represents 24-bit groups of input bits as output
74 strings of 4 encoded characters. Proceeding from left to right, a
75 24-bit input group is formed by concatenating 3 8-bit input groups.
76 These 24 bits are then treated as 4 concatenated 6-bit groups, each
77 of which is translated into a single digit in the base64 alphabet.
78
79 Each 6-bit group is used as an index into an array of 64 printable
80 characters. The character referenced by the index is placed in the
81 output string.
82
83 Table 1: The Base64 Alphabet
84
85 Value Encoding Value Encoding Value Encoding Value Encoding
86 0 A 17 R 34 i 51 z
87 1 B 18 S 35 j 52 0
88 2 C 19 T 36 k 53 1
89 3 D 20 U 37 l 54 2
90 4 E 21 V 38 m 55 3
91 5 F 22 W 39 n 56 4
92 6 G 23 X 40 o 57 5
93 7 H 24 Y 41 p 58 6
94 8 I 25 Z 42 q 59 7
95 9 J 26 a 43 r 60 8
96 10 K 27 b 44 s 61 9
97 11 L 28 c 45 t 62 +
98 12 M 29 d 46 u 63 /
99 13 N 30 e 47 v
100 14 O 31 f 48 w (pad) =
101 15 P 32 g 49 x
102 16 Q 33 h 50 y
103
104 Special processing is performed if fewer than 24 bits are available
105 at the end of the data being encoded. A full encoding quantum is
106 always completed at the end of a quantity. When fewer than 24 input
107 bits are available in an input group, zero bits are added (on the
108 right) to form an integral number of 6-bit groups. Padding at the
109 end of the data is performed using the '=' character.
110
111 Since all base64 input is an integral number of octets, only the
112 -------------------------------------------------
113 following cases can arise:
114
115 (1) the final quantum of encoding input is an integral
116 multiple of 24 bits; here, the final unit of encoded
117 output will be an integral multiple of 4 characters
118 with no "=" padding,
119 (2) the final quantum of encoding input is exactly 8 bits;
120 here, the final unit of encoded output will be two
121 characters followed by two "=" padding characters, or
122 (3) the final quantum of encoding input is exactly 16 bits;
123 here, the final unit of encoded output will be three
124 characters followed by one "=" padding character.
125 */
126
127 int
b64_ntop(u_char const * src,size_t srclength,char * target,size_t targsize)128 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize)
129 {
130 size_t datalength = 0;
131 u_char input[3];
132 u_char output[4];
133 size_t i;
134
135 while (2 < srclength) {
136 input[0] = *src++;
137 input[1] = *src++;
138 input[2] = *src++;
139 srclength -= 3;
140
141 output[0] = input[0] >> 2;
142 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
143 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
144 output[3] = input[2] & 0x3f;
145
146 if (datalength + 4 > targsize)
147 return (-1);
148 target[datalength++] = mbsd_digits_base64[output[0]];
149 target[datalength++] = mbsd_digits_base64[output[1]];
150 target[datalength++] = mbsd_digits_base64[output[2]];
151 target[datalength++] = mbsd_digits_base64[output[3]];
152 }
153
154 /* Now we worry about padding. */
155 if (0 != srclength) {
156 /* Get what's left. */
157 input[0] = input[1] = input[2] = '\0';
158 for (i = 0; i < srclength; i++)
159 input[i] = *src++;
160
161 output[0] = input[0] >> 2;
162 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
163 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
164
165 if (datalength + 4 > targsize)
166 return (-1);
167 target[datalength++] = mbsd_digits_base64[output[0]];
168 target[datalength++] = mbsd_digits_base64[output[1]];
169 if (srclength == 1)
170 target[datalength++] = Pad64;
171 else
172 target[datalength++] = mbsd_digits_base64[output[2]];
173 target[datalength++] = Pad64;
174 }
175 if (datalength >= targsize)
176 return (-1);
177 target[datalength] = '\0'; /* Returned value doesn't count \0. */
178 return (datalength);
179 }
180
181 /* skips all whitespace anywhere.
182 converts characters, four at a time, starting at (or after)
183 src from base - 64 numbers into three 8 bit bytes in the target area.
184 it returns the number of data bytes stored at the target, or -1 on error.
185 */
186
187 int
b64_pton(char const * src,u_char * target,size_t targsize)188 b64_pton(char const *src, u_char *target, size_t targsize)
189 {
190 size_t tarindex;
191 int state, ch;
192 u_char nextbyte;
193 const uint8_t *pos;
194
195 state = 0;
196 tarindex = 0;
197
198 while ((ch = (unsigned char)*src++) != '\0') {
199 if (isspace(ch)) /* Skip whitespace anywhere. */
200 continue;
201
202 if (ch == Pad64)
203 break;
204
205 pos = strchr(mbsd_digits_base64, ch);
206 if (pos == 0) /* 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 - &mbsd_digits_base64[0]) << 2;
215 }
216 state = 1;
217 break;
218 case 1:
219 if (target) {
220 if (tarindex >= targsize)
221 return (-1);
222 target[tarindex] |= (pos - &mbsd_digits_base64[0]) >> 4;
223 nextbyte = ((pos - &mbsd_digits_base64[0]) & 0x0f) << 4;
224 if (tarindex + 1 < targsize)
225 target[tarindex+1] = nextbyte;
226 else if (nextbyte)
227 return (-1);
228 }
229 tarindex++;
230 state = 2;
231 break;
232 case 2:
233 if (target) {
234 if (tarindex >= targsize)
235 return (-1);
236 target[tarindex] |= (pos - &mbsd_digits_base64[0]) >> 2;
237 nextbyte = ((pos - &mbsd_digits_base64[0]) & 0x03) << 6;
238 if (tarindex + 1 < targsize)
239 target[tarindex+1] = nextbyte;
240 else if (nextbyte)
241 return (-1);
242 }
243 tarindex++;
244 state = 3;
245 break;
246 case 3:
247 if (target) {
248 if (tarindex >= targsize)
249 return (-1);
250 target[tarindex] |= (pos - &mbsd_digits_base64[0]);
251 }
252 tarindex++;
253 state = 0;
254 break;
255 }
256 }
257
258 /*
259 * We are done decoding Base-64 chars. Let's see if we ended
260 * on a byte boundary, and/or with erroneous trailing characters.
261 */
262
263 if (ch == Pad64) { /* We got a pad char. */
264 ch = (unsigned char)*src++; /* Skip it, get next. */
265 switch (state) {
266 case 0: /* Invalid = in first position */
267 case 1: /* Invalid = in second position */
268 return (-1);
269
270 case 2: /* Valid, means one byte of info */
271 /* Skip any number of spaces. */
272 for (; ch != '\0'; ch = (unsigned char)*src++)
273 if (!isspace(ch))
274 break;
275 /* Make sure there is another trailing = sign. */
276 if (ch != Pad64)
277 return (-1);
278 ch = (unsigned char)*src++; /* Skip the = */
279 /* Fall through to "single trailing =" case. */
280 /* FALLTHROUGH */
281
282 case 3: /* Valid, means two bytes of info */
283 /*
284 * We know this char is an =. Is there anything but
285 * whitespace after it?
286 */
287 for (; ch != '\0'; ch = (unsigned char)*src++)
288 if (!isspace(ch))
289 return (-1);
290
291 /*
292 * Now make sure for cases 2 and 3 that the "extra"
293 * bits that slopped past the last full byte were
294 * zeros. If we don't check them, they become a
295 * subliminal channel.
296 */
297 if (target && tarindex < targsize &&
298 target[tarindex] != 0)
299 return (-1);
300 }
301 } else {
302 /*
303 * We ended by seeing the end of the string. Make sure we
304 * have no partial bytes lying around.
305 */
306 if (state != 0)
307 return (-1);
308 }
309
310 return (tarindex);
311 }
312