2 * Modified by Kurt D. Zeilenga for inclusion into OpenLDAP
6 * Copyright (c) 1996, 1998 by Internet Software Consortium.
8 * Permission to use, copy, modify, and distribute this software for any
9 * purpose with or without fee is hereby granted, provided that the above
10 * copyright notice and this permission notice appear in all copies.
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13 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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16 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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18 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
23 * Portions Copyright (c) 1995 by International Business Machines, Inc.
25 * International Business Machines, Inc. (hereinafter called IBM) grants
26 * permission under its copyrights to use, copy, modify, and distribute this
27 * Software with or without fee, provided that the above copyright notice and
28 * all paragraphs of this notice appear in all copies, and that the name of IBM
29 * not be used in connection with the marketing of any product incorporating
30 * the Software or modifications thereof, without specific, written prior
33 * To the extent it has a right to do so, IBM grants an immunity from suit
34 * under its patents, if any, for the use, sale or manufacture of products to
35 * the extent that such products are used for performing Domain Name System
36 * dynamic updates in TCP/IP networks by means of the Software. No immunity is
37 * granted for any product per se or for any other function of any product.
39 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
40 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
41 * PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
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49 #include <ac/stdlib.h>
51 #include <ac/string.h>
53 /* include socket.h to get sys/types.h and/or winsock2.h */
54 #include <ac/socket.h>
58 #define Assert(Cond) if (!(Cond)) abort()
60 static const char Base64[] =
61 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
62 static const char Pad64 = '=';
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
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.)
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.
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
83 Table 1: The Base64 Alphabet
85 Value Encoding Value Encoding Value Encoding Value Encoding
100 14 O 31 f 48 w (pad) =
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.
111 Since all base64 input is an integral number of octets, only the
112 -------------------------------------------------
113 following cases can arise:
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
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.
134 size_t datalength = 0;
139 while (2 < srclength) {
145 output[0] = input[0] >> 2;
146 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
147 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
148 output[3] = input[2] & 0x3f;
149 Assert(output[0] < 64);
150 Assert(output[1] < 64);
151 Assert(output[2] < 64);
152 Assert(output[3] < 64);
154 if (datalength + 4 > targsize)
156 target[datalength++] = Base64[output[0]];
157 target[datalength++] = Base64[output[1]];
158 target[datalength++] = Base64[output[2]];
159 target[datalength++] = Base64[output[3]];
162 /* Now we worry about padding. */
163 if (0 != srclength) {
164 /* Get what's left. */
165 input[0] = input[1] = input[2] = '\0';
166 for (i = 0; i < srclength; i++)
169 output[0] = input[0] >> 2;
170 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
171 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
172 Assert(output[0] < 64);
173 Assert(output[1] < 64);
174 Assert(output[2] < 64);
176 if (datalength + 4 > targsize)
178 target[datalength++] = Base64[output[0]];
179 target[datalength++] = Base64[output[1]];
181 target[datalength++] = Pad64;
183 target[datalength++] = Base64[output[2]];
184 target[datalength++] = Pad64;
186 if (datalength >= targsize)
188 target[datalength] = '\0'; /* Returned value doesn't count \0. */
192 /* skips all whitespace anywhere.
193 converts characters, four at a time, starting at (or after)
194 src from base - 64 numbers into three 8 bit bytes in the target area.
195 it returns the number of data bytes stored at the target, or -1 on error.
204 int tarindex, state, ch;
210 while ((ch = *src++) != '\0') {
211 if (isascii(ch) && isspace(ch)) /* Skip whitespace anywhere. */
217 pos = strchr(Base64, ch);
218 if (pos == 0) /* A non-base64 character. */
224 if ((size_t)tarindex >= targsize)
226 target[tarindex] = (pos - Base64) << 2;
232 if ((size_t)tarindex + 1 >= targsize)
234 target[tarindex] |= (pos - Base64) >> 4;
235 target[tarindex+1] = ((pos - Base64) & 0x0f)
243 if ((size_t)tarindex + 1 >= targsize)
245 target[tarindex] |= (pos - Base64) >> 2;
246 target[tarindex+1] = ((pos - Base64) & 0x03)
254 if ((size_t)tarindex >= targsize)
256 target[tarindex] |= (pos - Base64);
267 * We are done decoding Base-64 chars. Let's see if we ended
268 * on a byte boundary, and/or with erroneous trailing characters.
271 if (ch == Pad64) { /* We got a pad char. */
272 ch = *src++; /* Skip it, get next. */
274 case 0: /* Invalid = in first position */
275 case 1: /* Invalid = in second position */
278 case 2: /* Valid, means one byte of info */
279 /* Skip any number of spaces. */
280 for ((void)NULL; ch != '\0'; ch = *src++)
281 if (! (isascii(ch) && isspace(ch)))
283 /* Make sure there is another trailing = sign. */
286 ch = *src++; /* Skip the = */
287 /* Fall through to "single trailing =" case. */
290 case 3: /* Valid, means two bytes of info */
292 * We know this char is an =. Is there anything but
293 * whitespace after it?
295 for ((void)NULL; ch != '\0'; ch = *src++)
296 if (! (isascii(ch) && isspace(ch)))
300 * Now make sure for cases 2 and 3 that the "extra"
301 * bits that slopped past the last full byte were
302 * zeros. If we don't check them, they become a
303 * subliminal channel.
305 if (target && target[tarindex] != 0)
310 * We ended by seeing the end of the string. Make sure we
311 * have no partial bytes lying around.