1 /* $NetBSD: base64.c,v 1.17 2024/01/20 14:52:48 christos Exp $ */
2
3 /*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1996-1999 by Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 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/cdefs.h>
46 #if defined(LIBC_SCCS) && !defined(lint)
47 #if 0
48 static const char rcsid[] = "Id: base64.c,v 1.4 2005/04/27 04:56:34 sra Exp";
49 #else
50 __RCSID("$NetBSD: base64.c,v 1.17 2024/01/20 14:52:48 christos Exp $");
51 #endif
52 #endif /* LIBC_SCCS and not lint */
53
54 #include "port_before.h"
55
56 #include <sys/types.h>
57 #include <sys/param.h>
58 #include <sys/socket.h>
59
60 #include <netinet/in.h>
61 #include <arpa/inet.h>
62 #include <arpa/nameser.h>
63
64 #include <assert.h>
65 #include <ctype.h>
66 #include <resolv.h>
67 #include <stdio.h>
68 #include <stdlib.h>
69 #include <string.h>
70
71 #include "port_after.h"
72
73 #define Assert(Cond) if (!(Cond)) abort()
74
75 static const char Base64[] =
76 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
77 static const char Pad64 = '=';
78
79 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
80 The following encoding technique is taken from RFC1521 by Borenstein
81 and Freed. It is reproduced here in a slightly edited form for
82 convenience.
83
84 A 65-character subset of US-ASCII is used, enabling 6 bits to be
85 represented per printable character. (The extra 65th character, "=",
86 is used to signify a special processing function.)
87
88 The encoding process represents 24-bit groups of input bits as output
89 strings of 4 encoded characters. Proceeding from left to right, a
90 24-bit input group is formed by concatenating 3 8-bit input groups.
91 These 24 bits are then treated as 4 concatenated 6-bit groups, each
92 of which is translated into a single digit in the base64 alphabet.
93
94 Each 6-bit group is used as an index into an array of 64 printable
95 characters. The character referenced by the index is placed in the
96 output string.
97
98 Table 1: The Base64 Alphabet
99
100 Value Encoding Value Encoding Value Encoding Value Encoding
101 0 A 17 R 34 i 51 z
102 1 B 18 S 35 j 52 0
103 2 C 19 T 36 k 53 1
104 3 D 20 U 37 l 54 2
105 4 E 21 V 38 m 55 3
106 5 F 22 W 39 n 56 4
107 6 G 23 X 40 o 57 5
108 7 H 24 Y 41 p 58 6
109 8 I 25 Z 42 q 59 7
110 9 J 26 a 43 r 60 8
111 10 K 27 b 44 s 61 9
112 11 L 28 c 45 t 62 +
113 12 M 29 d 46 u 63 /
114 13 N 30 e 47 v
115 14 O 31 f 48 w (pad) =
116 15 P 32 g 49 x
117 16 Q 33 h 50 y
118
119 Special processing is performed if fewer than 24 bits are available
120 at the end of the data being encoded. A full encoding quantum is
121 always completed at the end of a quantity. When fewer than 24 input
122 bits are available in an input group, zero bits are added (on the
123 right) to form an integral number of 6-bit groups. Padding at the
124 end of the data is performed using the '=' character.
125
126 Since all base64 input is an integral number of octets, only the
127 -------------------------------------------------
128 following cases can arise:
129
130 (1) the final quantum of encoding input is an integral
131 multiple of 24 bits; here, the final unit of encoded
132 output will be an integral multiple of 4 characters
133 with no "=" padding,
134 (2) the final quantum of encoding input is exactly 8 bits;
135 here, the final unit of encoded output will be two
136 characters followed by two "=" padding characters, or
137 (3) the final quantum of encoding input is exactly 16 bits;
138 here, the final unit of encoded output will be three
139 characters followed by one "=" padding character.
140 */
141
142 int
b64_ntop(u_char const * src,size_t srclength,char * target,size_t targsize)143 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
144 size_t datalength = 0;
145 u_char input[3];
146 u_char output[4];
147 size_t i;
148
149 _DIAGASSERT(src != NULL);
150 _DIAGASSERT(target != NULL);
151
152 while (2U < srclength) {
153 input[0] = *src++;
154 input[1] = *src++;
155 input[2] = *src++;
156 srclength -= 3;
157
158 output[0] = (uint32_t)input[0] >> 2;
159 output[1] = ((uint32_t)(input[0] & 0x03) << 4) +
160 ((uint32_t)input[1] >> 4);
161 output[2] = ((uint32_t)(input[1] & 0x0f) << 2) +
162 ((uint32_t)input[2] >> 6);
163 output[3] = input[2] & 0x3f;
164 Assert(output[0] < 64);
165 Assert(output[1] < 64);
166 Assert(output[2] < 64);
167 Assert(output[3] < 64);
168
169 if (datalength + 4 > targsize)
170 return -1;
171 target[datalength++] = Base64[output[0]];
172 target[datalength++] = Base64[output[1]];
173 target[datalength++] = Base64[output[2]];
174 target[datalength++] = Base64[output[3]];
175 }
176
177 /* Now we worry about padding. */
178 if (0U != srclength) {
179 /* Get what's left. */
180 input[0] = input[1] = input[2] = '\0';
181 for (i = 0; i < srclength; i++)
182 input[i] = *src++;
183
184 output[0] = (uint32_t)input[0] >> 2;
185 output[1] = ((uint32_t)(input[0] & 0x03) << 4) +
186 ((uint32_t)input[1] >> 4);
187 output[2] = ((uint32_t)(input[1] & 0x0f) << 2) +
188 ((uint32_t)input[2] >> 6);
189 Assert(output[0] < 64);
190 Assert(output[1] < 64);
191 Assert(output[2] < 64);
192
193 if (datalength + 4 > targsize)
194 return -1;
195 target[datalength++] = Base64[output[0]];
196 target[datalength++] = Base64[output[1]];
197 if (srclength == 1U)
198 target[datalength++] = Pad64;
199 else
200 target[datalength++] = Base64[output[2]];
201 target[datalength++] = Pad64;
202 }
203 if (datalength >= targsize)
204 return -1;
205 target[datalength] = '\0'; /*%< Returned value doesn't count \\0. */
206 _DIAGASSERT(__type_fit(int, datalength));
207 return (int)datalength;
208 }
209
210 /* skips all whitespace anywhere.
211 converts characters, four at a time, starting at (or after)
212 src from base - 64 numbers into three 8 bit bytes in the target area.
213 it returns the number of data bytes stored at the target, or -1 on error.
214 */
215
216 int
b64_pton(char const * src,u_char * target,size_t targsize)217 b64_pton(char const *src, u_char *target, size_t targsize)
218 {
219 size_t tarindex;
220 int state, ch;
221 u_char nextbyte;
222 const char *pos;
223
224 _DIAGASSERT(src != NULL);
225 _DIAGASSERT(target != NULL);
226
227 state = 0;
228 tarindex = 0;
229
230 while ((ch = (u_char) *src++) != '\0') {
231 if (isspace(ch)) /*%< Skip whitespace anywhere. */
232 continue;
233
234 if (ch == Pad64)
235 break;
236
237 pos = strchr(Base64, ch);
238 if (pos == NULL) /*%< A non-base64 character. */
239 return -1;
240
241 switch (state) {
242 case 0:
243 if (target) {
244 if (tarindex >= targsize)
245 return -1;
246 target[tarindex] = (u_char)(pos - Base64) << 2;
247 }
248 state = 1;
249 break;
250 case 1:
251 if (target) {
252 if (tarindex >= targsize)
253 return -1;
254 target[tarindex] |=
255 (uint32_t)(pos - Base64) >> 4;
256 nextbyte = (u_char)((pos - Base64) & 0x0f) << 4;
257 if (tarindex + 1 < targsize)
258 target[tarindex + 1] = nextbyte;
259 else if (nextbyte)
260 return -1;
261 }
262 tarindex++;
263 state = 2;
264 break;
265 case 2:
266 if (target) {
267 if (tarindex >= targsize)
268 return -1;
269 target[tarindex] |=
270 (uint32_t)(pos - Base64) >> 2;
271 nextbyte = (u_char)((pos - Base64) & 0x03) << 6;
272 if (tarindex + 1 < targsize)
273 target[tarindex + 1] = nextbyte;
274 else if (nextbyte)
275 return -1;
276 }
277 tarindex++;
278 state = 3;
279 break;
280 case 3:
281 if (target) {
282 if ((size_t)tarindex >= targsize)
283 return -1;
284 target[tarindex] |= (u_char)(pos - Base64);
285 }
286 tarindex++;
287 state = 0;
288 break;
289 default:
290 abort();
291 }
292 }
293
294 /*
295 * We are done decoding Base-64 chars. Let's see if we ended
296 * on a byte boundary, and/or with erroneous trailing characters.
297 */
298
299 if (ch == Pad64) { /*%< We got a pad char. */
300 ch = *src++; /*%< Skip it, get next. */
301 switch (state) {
302 case 0: /*%< Invalid = in first position */
303 case 1: /*%< Invalid = in second position */
304 return -1;
305
306 case 2: /*%< Valid, means one byte of info */
307 /* Skip any number of spaces. */
308 for (; ch != '\0'; ch = (u_char) *src++)
309 if (!isspace(ch))
310 break;
311 /* Make sure there is another trailing = sign. */
312 if (ch != Pad64)
313 return -1;
314 ch = *src++; /*%< Skip the = */
315 /* Fall through to "single trailing =" case. */
316 /* FALLTHROUGH */
317
318 case 3: /*%< Valid, means two bytes of info */
319 /*
320 * We know this char is an =. Is there anything but
321 * whitespace after it?
322 */
323 for (; ch != '\0'; ch = (u_char) *src++)
324 if (!isspace(ch))
325 return -1;
326
327 /*
328 * Now make sure for cases 2 and 3 that the "extra"
329 * bits that slopped past the last full byte were
330 * zeros. If we don't check them, they become a
331 * subliminal channel.
332 */
333 if (target && tarindex < targsize &&
334 target[tarindex] != 0)
335 return -1;
336 }
337 } else {
338 /*
339 * We ended by seeing the end of the string. Make sure we
340 * have no partial bytes lying around.
341 */
342 if (state != 0)
343 return -1;
344 }
345
346 _DIAGASSERT(__type_fit(int, tarindex));
347 return (int)tarindex;
348 }
349
350 /*! \file */
351