2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996-1999 by Internet Software Consortium.
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19 * Portions Copyright (c) 1995 by International Business Machines, Inc.
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23 * Software with or without fee, provided that the above copyright notice and
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43 #if !defined(LINT) && !defined(CODECENTER)
44 static const char rcsid[] = "$Id: base64.c,v 1.1.2.2 2004/03/17 00:40:13 marka Exp $";
47 #include "port_before.h"
49 #include <sys/types.h>
50 #include <sys/param.h>
51 #include <sys/socket.h>
53 #include <netinet/in.h>
54 #include <arpa/inet.h>
55 #include <arpa/nameser.h>
63 #include "port_after.h"
65 #define Assert(Cond) if (!(Cond)) abort()
67 static const char Base64[] =
68 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
69 static const char Pad64 = '=';
71 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
72 The following encoding technique is taken from RFC 1521 by Borenstein
73 and Freed. It is reproduced here in a slightly edited form for
76 A 65-character subset of US-ASCII is used, enabling 6 bits to be
77 represented per printable character. (The extra 65th character, "=",
78 is used to signify a special processing function.)
80 The encoding process represents 24-bit groups of input bits as output
81 strings of 4 encoded characters. Proceeding from left to right, a
82 24-bit input group is formed by concatenating 3 8-bit input groups.
83 These 24 bits are then treated as 4 concatenated 6-bit groups, each
84 of which is translated into a single digit in the base64 alphabet.
86 Each 6-bit group is used as an index into an array of 64 printable
87 characters. The character referenced by the index is placed in the
90 Table 1: The Base64 Alphabet
92 Value Encoding Value Encoding Value Encoding Value Encoding
107 14 O 31 f 48 w (pad) =
111 Special processing is performed if fewer than 24 bits are available
112 at the end of the data being encoded. A full encoding quantum is
113 always completed at the end of a quantity. When fewer than 24 input
114 bits are available in an input group, zero bits are added (on the
115 right) to form an integral number of 6-bit groups. Padding at the
116 end of the data is performed using the '=' character.
118 Since all base64 input is an integral number of octets, only the
119 -------------------------------------------------
120 following cases can arise:
122 (1) the final quantum of encoding input is an integral
123 multiple of 24 bits; here, the final unit of encoded
124 output will be an integral multiple of 4 characters
126 (2) the final quantum of encoding input is exactly 8 bits;
127 here, the final unit of encoded output will be two
128 characters followed by two "=" padding characters, or
129 (3) the final quantum of encoding input is exactly 16 bits;
130 here, the final unit of encoded output will be three
131 characters followed by one "=" padding character.
135 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
136 size_t datalength = 0;
141 while (2U < srclength) {
147 output[0] = input[0] >> 2;
148 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
149 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
150 output[3] = input[2] & 0x3f;
151 Assert(output[0] < 64);
152 Assert(output[1] < 64);
153 Assert(output[2] < 64);
154 Assert(output[3] < 64);
156 if (datalength + 4 > targsize)
158 target[datalength++] = Base64[output[0]];
159 target[datalength++] = Base64[output[1]];
160 target[datalength++] = Base64[output[2]];
161 target[datalength++] = Base64[output[3]];
164 /* Now we worry about padding. */
165 if (0U != srclength) {
166 /* Get what's left. */
167 input[0] = input[1] = input[2] = '\0';
168 for (i = 0; i < srclength; i++)
171 output[0] = input[0] >> 2;
172 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
173 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
174 Assert(output[0] < 64);
175 Assert(output[1] < 64);
176 Assert(output[2] < 64);
178 if (datalength + 4 > targsize)
180 target[datalength++] = Base64[output[0]];
181 target[datalength++] = Base64[output[1]];
183 target[datalength++] = Pad64;
185 target[datalength++] = Base64[output[2]];
186 target[datalength++] = Pad64;
188 if (datalength >= targsize)
190 target[datalength] = '\0'; /* Returned value doesn't count \0. */
194 /* skips all whitespace anywhere.
195 converts characters, four at a time, starting at (or after)
196 src from base - 64 numbers into three 8 bit bytes in the target area.
197 it returns the number of data bytes stored at the target, or -1 on error.
201 b64_pton(src, target, targsize)
206 int tarindex, state, ch;
212 while ((ch = *src++) != '\0') {
213 if (isspace(ch)) /* Skip whitespace anywhere. */
219 pos = strchr(Base64, ch);
220 if (pos == 0) /* A non-base64 character. */
226 if ((size_t)tarindex >= targsize)
228 target[tarindex] = (pos - Base64) << 2;
234 if ((size_t)tarindex + 1 >= targsize)
236 target[tarindex] |= (pos - Base64) >> 4;
237 target[tarindex+1] = ((pos - Base64) & 0x0f)
245 if ((size_t)tarindex + 1 >= targsize)
247 target[tarindex] |= (pos - Base64) >> 2;
248 target[tarindex+1] = ((pos - Base64) & 0x03)
256 if ((size_t)tarindex >= targsize)
258 target[tarindex] |= (pos - Base64);
269 * We are done decoding Base-64 chars. Let's see if we ended
270 * on a byte boundary, and/or with erroneous trailing characters.
273 if (ch == Pad64) { /* We got a pad char. */
274 ch = *src++; /* Skip it, get next. */
276 case 0: /* Invalid = in first position */
277 case 1: /* Invalid = in second position */
280 case 2: /* Valid, means one byte of info */
281 /* Skip any number of spaces. */
282 for ((void)NULL; ch != '\0'; ch = *src++)
285 /* Make sure there is another trailing = sign. */
288 ch = *src++; /* Skip the = */
289 /* Fall through to "single trailing =" case. */
292 case 3: /* Valid, means two bytes of info */
294 * We know this char is an =. Is there anything but
295 * whitespace after it?
297 for ((void)NULL; ch != '\0'; ch = *src++)
302 * Now make sure for cases 2 and 3 that the "extra"
303 * bits that slopped past the last full byte were
304 * zeros. If we don't check them, they become a
305 * subliminal channel.
307 if (target && target[tarindex] != 0)
312 * We ended by seeing the end of the string. Make sure we
313 * have no partial bytes lying around.