1 /* OPENBSD ORIGINAL: lib/libc/net/base64.c */
3 /* $OpenBSD: base64.c,v 1.4 2002/01/02 23:00:10 deraadt Exp $ */
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49 #if (!defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP)) || (!defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON))
51 #include <sys/types.h>
52 #include <sys/param.h>
53 #include <sys/socket.h>
54 #include <netinet/in.h>
55 #include <arpa/inet.h>
65 /* XXX abort illegal in library */
66 #define Assert(Cond) if (!(Cond)) abort()
68 static const char Base64[] =
69 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
70 static const char Pad64 = '=';
72 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
73 The following encoding technique is taken from RFC 1521 by Borenstein
74 and Freed. It is reproduced here in a slightly edited form for
77 A 65-character subset of US-ASCII is used, enabling 6 bits to be
78 represented per printable character. (The extra 65th character, "=",
79 is used to signify a special processing function.)
81 The encoding process represents 24-bit groups of input bits as output
82 strings of 4 encoded characters. Proceeding from left to right, a
83 24-bit input group is formed by concatenating 3 8-bit input groups.
84 These 24 bits are then treated as 4 concatenated 6-bit groups, each
85 of which is translated into a single digit in the base64 alphabet.
87 Each 6-bit group is used as an index into an array of 64 printable
88 characters. The character referenced by the index is placed in the
91 Table 1: The Base64 Alphabet
93 Value Encoding Value Encoding Value Encoding Value Encoding
108 14 O 31 f 48 w (pad) =
112 Special processing is performed if fewer than 24 bits are available
113 at the end of the data being encoded. A full encoding quantum is
114 always completed at the end of a quantity. When fewer than 24 input
115 bits are available in an input group, zero bits are added (on the
116 right) to form an integral number of 6-bit groups. Padding at the
117 end of the data is performed using the '=' character.
119 Since all base64 input is an integral number of octets, only the
120 -------------------------------------------------
121 following cases can arise:
123 (1) the final quantum of encoding input is an integral
124 multiple of 24 bits; here, the final unit of encoded
125 output will be an integral multiple of 4 characters
127 (2) the final quantum of encoding input is exactly 8 bits;
128 here, the final unit of encoded output will be two
129 characters followed by two "=" padding characters, or
130 (3) the final quantum of encoding input is exactly 16 bits;
131 here, the final unit of encoded output will be three
132 characters followed by one "=" padding character.
135 #if !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP)
137 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize)
139 size_t datalength = 0;
144 while (2 < srclength) {
150 output[0] = input[0] >> 2;
151 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
152 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
153 output[3] = input[2] & 0x3f;
154 Assert(output[0] < 64);
155 Assert(output[1] < 64);
156 Assert(output[2] < 64);
157 Assert(output[3] < 64);
159 if (datalength + 4 > targsize)
161 target[datalength++] = Base64[output[0]];
162 target[datalength++] = Base64[output[1]];
163 target[datalength++] = Base64[output[2]];
164 target[datalength++] = Base64[output[3]];
167 /* Now we worry about padding. */
168 if (0 != srclength) {
169 /* Get what's left. */
170 input[0] = input[1] = input[2] = '\0';
171 for (i = 0; i < srclength; i++)
174 output[0] = input[0] >> 2;
175 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
176 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
177 Assert(output[0] < 64);
178 Assert(output[1] < 64);
179 Assert(output[2] < 64);
181 if (datalength + 4 > targsize)
183 target[datalength++] = Base64[output[0]];
184 target[datalength++] = Base64[output[1]];
186 target[datalength++] = Pad64;
188 target[datalength++] = Base64[output[2]];
189 target[datalength++] = Pad64;
191 if (datalength >= targsize)
193 target[datalength] = '\0'; /* Returned value doesn't count \0. */
196 #endif /* !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) */
198 #if !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON)
200 /* skips all whitespace anywhere.
201 converts characters, four at a time, starting at (or after)
202 src from base - 64 numbers into three 8 bit bytes in the target area.
203 it returns the number of data bytes stored at the target, or -1 on error.
207 b64_pton(char const *src, u_char *target, size_t targsize)
209 int tarindex, state, ch;
215 while ((ch = *src++) != '\0') {
216 if (isspace(ch)) /* Skip whitespace anywhere. */
222 pos = strchr(Base64, ch);
223 if (pos == 0) /* A non-base64 character. */
229 if (tarindex >= targsize)
231 target[tarindex] = (pos - Base64) << 2;
237 if (tarindex + 1 >= targsize)
239 target[tarindex] |= (pos - Base64) >> 4;
240 target[tarindex+1] = ((pos - Base64) & 0x0f)
248 if (tarindex + 1 >= targsize)
250 target[tarindex] |= (pos - Base64) >> 2;
251 target[tarindex+1] = ((pos - Base64) & 0x03)
259 if (tarindex >= targsize)
261 target[tarindex] |= (pos - Base64);
270 * We are done decoding Base-64 chars. Let's see if we ended
271 * on a byte boundary, and/or with erroneous trailing characters.
274 if (ch == Pad64) { /* We got a pad char. */
275 ch = *src++; /* Skip it, get next. */
277 case 0: /* Invalid = in first position */
278 case 1: /* Invalid = in second position */
281 case 2: /* Valid, means one byte of info */
282 /* Skip any number of spaces. */
283 for (; ch != '\0'; ch = *src++)
286 /* Make sure there is another trailing = sign. */
289 ch = *src++; /* Skip the = */
290 /* Fall through to "single trailing =" case. */
293 case 3: /* Valid, means two bytes of info */
295 * We know this char is an =. Is there anything but
296 * whitespace after it?
298 for (; ch != '\0'; ch = *src++)
303 * Now make sure for cases 2 and 3 that the "extra"
304 * bits that slopped past the last full byte were
305 * zeros. If we don't check them, they become a
306 * subliminal channel.
308 if (target && target[tarindex] != 0)
313 * We ended by seeing the end of the string. Make sure we
314 * have no partial bytes lying around.
323 #endif /* !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON) */