2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996-2003 by Internet Software Consortium
5 * Permission to use, copy, modify, and distribute this software for any
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15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 * Internet Systems Consortium, Inc.
19 * Redwood City, CA 94063
25 * Portions Copyright (c) 1995 by International Business Machines, Inc.
27 * International Business Machines, Inc. (hereinafter called IBM) grants
28 * permission under its copyrights to use, copy, modify, and distribute this
29 * Software with or without fee, provided that the above copyright notice and
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32 * the Software or modifications thereof, without specific, written prior
35 * To the extent it has a right to do so, IBM grants an immunity from suit
36 * under its patents, if any, for the use, sale or manufacture of products to
37 * the extent that such products are used for performing Domain Name System
38 * dynamic updates in TCP/IP networks by means of the Software. No immunity is
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49 #if !defined(LINT) && !defined(CODECENTER)
50 static const char rcsid[] = "$Id: base64.c,v 1.1.2.1 2004/06/10 17:59:28 dhankins Exp $";
53 #include <sys/types.h>
54 #include <sys/param.h>
55 #include <sys/socket.h>
57 #include <netinet/in.h>
58 #include <arpa/inet.h>
65 #include <sys/socket.h>
67 #include "minires/minires.h"
68 #include "arpa/nameser.h"
70 #define Assert(Cond) if (!(Cond)) abort()
72 static const char Base64[] =
73 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
74 static const char Pad64 = '=';
76 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
77 The following encoding technique is taken from RFC 1521 by Borenstein
78 and Freed. It is reproduced here in a slightly edited form for
81 A 65-character subset of US-ASCII is used, enabling 6 bits to be
82 represented per printable character. (The extra 65th character, "=",
83 is used to signify a special processing function.)
85 The encoding process represents 24-bit groups of input bits as output
86 strings of 4 encoded characters. Proceeding from left to right, a
87 24-bit input group is formed by concatenating 3 8-bit input groups.
88 These 24 bits are then treated as 4 concatenated 6-bit groups, each
89 of which is translated into a single digit in the base64 alphabet.
91 Each 6-bit group is used as an index into an array of 64 printable
92 characters. The character referenced by the index is placed in the
95 Table 1: The Base64 Alphabet
97 Value Encoding Value Encoding Value Encoding Value Encoding
112 14 O 31 f 48 w (pad) =
116 Special processing is performed if fewer than 24 bits are available
117 at the end of the data being encoded. A full encoding quantum is
118 always completed at the end of a quantity. When fewer than 24 input
119 bits are available in an input group, zero bits are added (on the
120 right) to form an integral number of 6-bit groups. Padding at the
121 end of the data is performed using the '=' character.
123 Since all base64 input is an integral number of octets, only the
124 -------------------------------------------------
125 following cases can arise:
127 (1) the final quantum of encoding input is an integral
128 multiple of 24 bits; here, the final unit of encoded
129 output will be an integral multiple of 4 characters
131 (2) the final quantum of encoding input is exactly 8 bits;
132 here, the final unit of encoded output will be two
133 characters followed by two "=" padding characters, or
134 (3) the final quantum of encoding input is exactly 16 bits;
135 here, the final unit of encoded output will be three
136 characters followed by one "=" padding character.
140 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
141 size_t datalength = 0;
146 while (2 < srclength) {
152 output[0] = input[0] >> 2;
153 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
154 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
155 output[3] = input[2] & 0x3f;
156 Assert(output[0] < 64);
157 Assert(output[1] < 64);
158 Assert(output[2] < 64);
159 Assert(output[3] < 64);
161 if (datalength + 4 > targsize)
163 target[datalength++] = Base64[output[0]];
164 target[datalength++] = Base64[output[1]];
165 target[datalength++] = Base64[output[2]];
166 target[datalength++] = Base64[output[3]];
169 /* Now we worry about padding. */
170 if (0 != srclength) {
171 /* Get what's left. */
172 input[0] = input[1] = input[2] = '\0';
173 for (i = 0; i < srclength; i++)
176 output[0] = input[0] >> 2;
177 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
178 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
179 Assert(output[0] < 64);
180 Assert(output[1] < 64);
181 Assert(output[2] < 64);
183 if (datalength + 4 > targsize)
185 target[datalength++] = Base64[output[0]];
186 target[datalength++] = Base64[output[1]];
188 target[datalength++] = Pad64;
190 target[datalength++] = Base64[output[2]];
191 target[datalength++] = Pad64;
193 if (datalength >= targsize)
195 target[datalength] = '\0'; /* Returned value doesn't count \0. */
199 /* skips all whitespace anywhere.
200 converts characters, four at a time, starting at (or after)
201 src from base - 64 numbers into three 8 bit bytes in the target area.
202 it returns the number of data bytes stored at the target, or -1 on error.
206 b64_pton(src, target, targsize)
211 int tarindex, state, ch;
217 while ((ch = *src++) != '\0') {
218 if (isspace(ch)) /* Skip whitespace anywhere. */
224 pos = strchr(Base64, ch);
225 if (pos == 0) /* A non-base64 character. */
231 if ((size_t)tarindex >= targsize)
233 target[tarindex] = (pos - Base64) << 2;
239 if ((size_t)tarindex + 1 >= targsize)
241 target[tarindex] |= (pos - Base64) >> 4;
242 target[tarindex+1] = ((pos - Base64) & 0x0f)
250 if ((size_t)tarindex + 1 >= targsize)
252 target[tarindex] |= (pos - Base64) >> 2;
253 target[tarindex+1] = ((pos - Base64) & 0x03)
261 if ((size_t)tarindex >= targsize)
263 target[tarindex] |= (pos - Base64);
274 * We are done decoding Base-64 chars. Let's see if we ended
275 * on a byte boundary, and/or with erroneous trailing characters.
278 if (ch == Pad64) { /* We got a pad char. */
279 ch = *src++; /* Skip it, get next. */
281 case 0: /* Invalid = in first position */
282 case 1: /* Invalid = in second position */
285 case 2: /* Valid, means one byte of info */
286 /* Skip any number of spaces. */
287 for ((void)NULL; ch != '\0'; ch = *src++)
290 /* Make sure there is another trailing = sign. */
293 ch = *src++; /* Skip the = */
294 /* Fall through to "single trailing =" case. */
297 case 3: /* Valid, means two bytes of info */
299 * We know this char is an =. Is there anything but
300 * whitespace after it?
302 for ((void)NULL; ch != '\0'; ch = *src++)
307 * Now make sure for cases 2 and 3 that the "extra"
308 * bits that slopped past the last full byte were
309 * zeros. If we don't check them, they become a
310 * subliminal channel.
312 if (target && target[tarindex] != 0)
317 * We ended by seeing the end of the string. Make sure we
318 * have no partial bytes lying around.