source: rtems/cpukit/libnetworking/libc/base64.c @ 39e6e65a

4.104.114.84.95
Last change on this file since 39e6e65a was 39e6e65a, checked in by Joel Sherrill <joel.sherrill@…>, on 08/19/98 at 21:32:28

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1/*
2 * Copyright (c) 1996, 1998 by Internet Software Consortium.
3 *
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.
7 *
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.
16 */
17
18/*
19 * Portions Copyright (c) 1995 by International Business Machines, Inc.
20 *
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.
28 *
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.
34 *
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.
41 */
42
43#if !defined(LINT) && !defined(CODECENTER)
44static char rcsid[] = "$Id$";
45#endif /* not lint */
46
47#include <sys/types.h>
48#include <sys/param.h>
49#include <sys/socket.h>
50
51#include <netinet/in.h>
52#include <arpa/inet.h>
53#include <arpa/nameser.h>
54
55#include <ctype.h>
56#include <resolv.h>
57#include <stdio.h>
58#include <stdlib.h>
59#include <string.h>
60
61#define Assert(Cond) if (!(Cond)) abort()
62
63static const char Base64[] =
64        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
65static const char Pad64 = '=';
66
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.
71
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.)
75
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.
81
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.
85
86                         Table 1: The Base64 Alphabet
87
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
106
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.
113
114   Since all base64 input is an integral number of octets, only the
115         -------------------------------------------------                       
116   following cases can arise:
117   
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.
128   */
129
130int
131b64_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;
136
137        while (2 < srclength) {
138                input[0] = *src++;
139                input[1] = *src++;
140                input[2] = *src++;
141                srclength -= 3;
142
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);
151
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]];
158        }
159   
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++;
166       
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);
173
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;
183        }
184        if (datalength >= targsize)
185                return (-1);
186        target[datalength] = '\0';      /* Returned value doesn't count \0. */
187        return (datalength);
188}
189
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.
194 */
195
196int
197b64_pton(src, target, targsize)
198        char const *src;
199        u_char *target;
200        size_t targsize;
201{
202        int tarindex, state, ch;
203        char *pos;
204
205        state = 0;
206        tarindex = 0;
207
208        while ((ch = *src++) != '\0') {
209                if (isspace(ch))        /* Skip whitespace anywhere. */
210                        continue;
211
212                if (ch == Pad64)
213                        break;
214
215                pos = strchr(Base64, ch);
216                if (pos == 0)           /* A non-base64 character. */
217                        return (-1);
218
219                switch (state) {
220                case 0:
221                        if (target) {
222                                if ((size_t)tarindex >= targsize)
223                                        return (-1);
224                                target[tarindex] = (pos - Base64) << 2;
225                        }
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 ;
235                        }
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;
246                        }
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);
255                        }
256                        tarindex++;
257                        state = 0;
258                        break;
259                default:
260                        abort();
261                }
262        }
263
264        /*
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.
267         */
268
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);
275
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 */
287
288                case 3:         /* Valid, means two bytes of info */
289                        /*
290                         * We know this char is an =.  Is there anything but
291                         * whitespace after it?
292                         */
293                        for ((void)NULL; ch != '\0'; ch = *src++)
294                                if (!isspace(ch))
295                                        return (-1);
296
297                        /*
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.
302                         */
303                        if (target && target[tarindex] != 0)
304                                return (-1);
305                }
306        } else {
307                /*
308                 * We ended by seeing the end of the string.  Make sure we
309                 * have no partial bytes lying around.
310                 */
311                if (state != 0)
312                        return (-1);
313        }
314
315        return (tarindex);
316}
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