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[glibc.git] / resolv / base64.c
blobb7c7d1c1b8985ce1b3b1906409fef6dea623ecae
1 /*
2 * Copyright (c) 1996-1999 by Internet Software Consortium.
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
9 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
10 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
11 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
12 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
13 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
15 * SOFTWARE.
19 * Portions Copyright (c) 1995 by International Business Machines, Inc.
21 * International Business Machines, Inc. (hereinafter called IBM) grants
22 * permission under its copyrights to use, copy, modify, and distribute this
23 * Software with or without fee, provided that the above copyright notice and
24 * all paragraphs of this notice appear in all copies, and that the name of IBM
25 * not be used in connection with the marketing of any product incorporating
26 * the Software or modifications thereof, without specific, written prior
27 * permission.
29 * To the extent it has a right to do so, IBM grants an immunity from suit
30 * under its patents, if any, for the use, sale or manufacture of products to
31 * the extent that such products are used for performing Domain Name System
32 * dynamic updates in TCP/IP networks by means of the Software. No immunity is
33 * granted for any product per se or for any other function of any product.
35 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
36 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
37 * PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
38 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
39 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
40 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
43 #if !defined(LINT) && !defined(CODECENTER)
44 static const char rcsid[] = "$BINDId: base64.c,v 8.7 1999/10/13 16:39:33 vixie Exp $";
45 #endif /* not lint */
47 #include <sys/types.h>
48 #include <sys/param.h>
49 #include <sys/socket.h>
51 #include <netinet/in.h>
52 #include <arpa/inet.h>
53 #include <arpa/nameser.h>
55 #include <ctype.h>
56 #include <resolv.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
61 #define Assert(Cond) if (!(Cond)) abort()
63 static const char Base64[] =
64 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
65 static const char Pad64 = '=';
67 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
68 The following encoding technique is taken from RFC 1521 by Borenstein
69 and Freed. It is reproduced here in a slightly edited form for
70 convenience.
72 A 65-character subset of US-ASCII is used, enabling 6 bits to be
73 represented per printable character. (The extra 65th character, "=",
74 is used to signify a special processing function.)
76 The encoding process represents 24-bit groups of input bits as output
77 strings of 4 encoded characters. Proceeding from left to right, a
78 24-bit input group is formed by concatenating 3 8-bit input groups.
79 These 24 bits are then treated as 4 concatenated 6-bit groups, each
80 of which is translated into a single digit in the base64 alphabet.
82 Each 6-bit group is used as an index into an array of 64 printable
83 characters. The character referenced by the index is placed in the
84 output string.
86 Table 1: The Base64 Alphabet
88 Value Encoding Value Encoding Value Encoding Value Encoding
89 0 A 17 R 34 i 51 z
90 1 B 18 S 35 j 52 0
91 2 C 19 T 36 k 53 1
92 3 D 20 U 37 l 54 2
93 4 E 21 V 38 m 55 3
94 5 F 22 W 39 n 56 4
95 6 G 23 X 40 o 57 5
96 7 H 24 Y 41 p 58 6
97 8 I 25 Z 42 q 59 7
98 9 J 26 a 43 r 60 8
99 10 K 27 b 44 s 61 9
100 11 L 28 c 45 t 62 +
101 12 M 29 d 46 u 63 /
102 13 N 30 e 47 v
103 14 O 31 f 48 w (pad) =
104 15 P 32 g 49 x
105 16 Q 33 h 50 y
107 Special processing is performed if fewer than 24 bits are available
108 at the end of the data being encoded. A full encoding quantum is
109 always completed at the end of a quantity. When fewer than 24 input
110 bits are available in an input group, zero bits are added (on the
111 right) to form an integral number of 6-bit groups. Padding at the
112 end of the data is performed using the '=' character.
114 Since all base64 input is an integral number of octets, only the
115 -------------------------------------------------
116 following cases can arise:
118 (1) the final quantum of encoding input is an integral
119 multiple of 24 bits; here, the final unit of encoded
120 output will be an integral multiple of 4 characters
121 with no "=" padding,
122 (2) the final quantum of encoding input is exactly 8 bits;
123 here, the final unit of encoded output will be two
124 characters followed by two "=" padding characters, or
125 (3) the final quantum of encoding input is exactly 16 bits;
126 here, the final unit of encoded output will be three
127 characters followed by one "=" padding character.
131 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
132 size_t datalength = 0;
133 u_char input[3];
134 u_char output[4];
135 size_t i;
137 while (2 < srclength) {
138 input[0] = *src++;
139 input[1] = *src++;
140 input[2] = *src++;
141 srclength -= 3;
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 Assert(output[0] < 64);
148 Assert(output[1] < 64);
149 Assert(output[2] < 64);
150 Assert(output[3] < 64);
152 if (datalength + 4 > targsize)
153 return (-1);
154 target[datalength++] = Base64[output[0]];
155 target[datalength++] = Base64[output[1]];
156 target[datalength++] = Base64[output[2]];
157 target[datalength++] = Base64[output[3]];
160 /* Now we worry about padding. */
161 if (0 != srclength) {
162 /* Get what's left. */
163 input[0] = input[1] = input[2] = '\0';
164 for (i = 0; i < srclength; i++)
165 input[i] = *src++;
167 output[0] = input[0] >> 2;
168 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
169 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
170 Assert(output[0] < 64);
171 Assert(output[1] < 64);
172 Assert(output[2] < 64);
174 if (datalength + 4 > targsize)
175 return (-1);
176 target[datalength++] = Base64[output[0]];
177 target[datalength++] = Base64[output[1]];
178 if (srclength == 1)
179 target[datalength++] = Pad64;
180 else
181 target[datalength++] = Base64[output[2]];
182 target[datalength++] = Pad64;
184 if (datalength >= targsize)
185 return (-1);
186 target[datalength] = '\0'; /* Returned value doesn't count \0. */
187 return (datalength);
190 /* skips all whitespace anywhere.
191 converts characters, four at a time, starting at (or after)
192 src from base - 64 numbers into three 8 bit bytes in the target area.
193 it returns the number of data bytes stored at the target, or -1 on error.
197 b64_pton(src, target, targsize)
198 char const *src;
199 u_char *target;
200 size_t targsize;
202 int tarindex, state, ch;
203 char *pos;
205 state = 0;
206 tarindex = 0;
208 while ((ch = *src++) != '\0') {
209 if (isspace(ch)) /* Skip whitespace anywhere. */
210 continue;
212 if (ch == Pad64)
213 break;
215 pos = strchr(Base64, ch);
216 if (pos == 0) /* A non-base64 character. */
217 return (-1);
219 switch (state) {
220 case 0:
221 if (target) {
222 if ((size_t)tarindex >= targsize)
223 return (-1);
224 target[tarindex] = (pos - Base64) << 2;
226 state = 1;
227 break;
228 case 1:
229 if (target) {
230 if ((size_t)tarindex + 1 >= targsize)
231 return (-1);
232 target[tarindex] |= (pos - Base64) >> 4;
233 target[tarindex+1] = ((pos - Base64) & 0x0f)
234 << 4 ;
236 tarindex++;
237 state = 2;
238 break;
239 case 2:
240 if (target) {
241 if ((size_t)tarindex + 1 >= targsize)
242 return (-1);
243 target[tarindex] |= (pos - Base64) >> 2;
244 target[tarindex+1] = ((pos - Base64) & 0x03)
245 << 6;
247 tarindex++;
248 state = 3;
249 break;
250 case 3:
251 if (target) {
252 if ((size_t)tarindex >= targsize)
253 return (-1);
254 target[tarindex] |= (pos - Base64);
256 tarindex++;
257 state = 0;
258 break;
259 default:
260 abort();
265 * We are done decoding Base-64 chars. Let's see if we ended
266 * on a byte boundary, and/or with erroneous trailing characters.
269 if (ch == Pad64) { /* We got a pad char. */
270 ch = *src++; /* Skip it, get next. */
271 switch (state) {
272 case 0: /* Invalid = in first position */
273 case 1: /* Invalid = in second position */
274 return (-1);
276 case 2: /* Valid, means one byte of info */
277 /* Skip any number of spaces. */
278 for ((void)NULL; ch != '\0'; ch = *src++)
279 if (!isspace(ch))
280 break;
281 /* Make sure there is another trailing = sign. */
282 if (ch != Pad64)
283 return (-1);
284 ch = *src++; /* Skip the = */
285 /* Fall through to "single trailing =" case. */
286 /* FALLTHROUGH */
288 case 3: /* Valid, means two bytes of info */
290 * We know this char is an =. Is there anything but
291 * whitespace after it?
293 for ((void)NULL; ch != '\0'; ch = *src++)
294 if (!isspace(ch))
295 return (-1);
298 * Now make sure for cases 2 and 3 that the "extra"
299 * bits that slopped past the last full byte were
300 * zeros. If we don't check them, they become a
301 * subliminal channel.
303 if (target && target[tarindex] != 0)
304 return (-1);
306 } else {
308 * We ended by seeing the end of the string. Make sure we
309 * have no partial bytes lying around.
311 if (state != 0)
312 return (-1);
315 return (tarindex);