1/*
2 * Copyright (c) 1996-1999 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 * Copyright (c) 1995 IBM Corporation
20 *
21 * Permission is hereby granted, free of charge, to any person obtaining
22 * a copy of this software and associated documentation files (the
23 * 'Software'), to deal in the Software without restriction, including
24 * without limitation the rights to use, copy, modify, merge, publish,
25 * distribute, sublicense, and/or sell copies of the Software, and to
26 * permit persons to whom the Software is furnished to do so, subject to
27 * the following conditions:
28 *
29 * The above copyright notice and this permission notice shall be
30 * included in all copies or substantial portions of the Software.
31 *
32 * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
33 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
34 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
35 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
36 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
37 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
38 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
39 */
40
41#include <sys/types.h>
42#include <sys/param.h>
43#include <sys/socket.h>
44
45#include <netinet/in.h>
46#include <arpa/inet.h>
47#include <arpa/nameser.h>
48
49#include <ctype.h>
50#include <resolv.h>
51#include <stdio.h>
52#include <stdlib.h>
53#include <string.h>
54
55#define Assert(Cond) if (!(Cond)) abort()
56
57static const char Base64[] =
58 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
59static const char Pad64 = '=';
60
61/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
62 The following encoding technique is taken from RFC 1521 by Borenstein
63 and Freed. It is reproduced here in a slightly edited form for
64 convenience.
65
66 A 65-character subset of US-ASCII is used, enabling 6 bits to be
67 represented per printable character. (The extra 65th character, "=",
68 is used to signify a special processing function.)
69
70 The encoding process represents 24-bit groups of input bits as output
71 strings of 4 encoded characters. Proceeding from left to right, a
72 24-bit input group is formed by concatenating 3 8-bit input groups.
73 These 24 bits are then treated as 4 concatenated 6-bit groups, each
74 of which is translated into a single digit in the base64 alphabet.
75
76 Each 6-bit group is used as an index into an array of 64 printable
77 characters. The character referenced by the index is placed in the
78 output string.
79
80 Table 1: The Base64 Alphabet
81
82 Value Encoding Value Encoding Value Encoding Value Encoding
83 0 A 17 R 34 i 51 z
84 1 B 18 S 35 j 52 0
85 2 C 19 T 36 k 53 1
86 3 D 20 U 37 l 54 2
87 4 E 21 V 38 m 55 3
88 5 F 22 W 39 n 56 4
89 6 G 23 X 40 o 57 5
90 7 H 24 Y 41 p 58 6
91 8 I 25 Z 42 q 59 7
92 9 J 26 a 43 r 60 8
93 10 K 27 b 44 s 61 9
94 11 L 28 c 45 t 62 +
95 12 M 29 d 46 u 63 /
96 13 N 30 e 47 v
97 14 O 31 f 48 w (pad) =
98 15 P 32 g 49 x
99 16 Q 33 h 50 y
100
101 Special processing is performed if fewer than 24 bits are available
102 at the end of the data being encoded. A full encoding quantum is
103 always completed at the end of a quantity. When fewer than 24 input
104 bits are available in an input group, zero bits are added (on the
105 right) to form an integral number of 6-bit groups. Padding at the
106 end of the data is performed using the '=' character.
107
108 Since all base64 input is an integral number of octets, only the
109 -------------------------------------------------
110 following cases can arise:
111
112 (1) the final quantum of encoding input is an integral
113 multiple of 24 bits; here, the final unit of encoded
114 output will be an integral multiple of 4 characters
115 with no "=" padding,
116 (2) the final quantum of encoding input is exactly 8 bits;
117 here, the final unit of encoded output will be two
118 characters followed by two "=" padding characters, or
119 (3) the final quantum of encoding input is exactly 16 bits;
120 here, the final unit of encoded output will be three
121 characters followed by one "=" padding character.
122 */
123
124int
125b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
126 size_t datalength = 0;
127 u_char input[3];
128 u_char output[4];
129 size_t i;
130
131 while (2 < srclength) {
132 input[0] = *src++;
133 input[1] = *src++;
134 input[2] = *src++;
135 srclength -= 3;
136
137 output[0] = input[0] >> 2;
138 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
139 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
140 output[3] = input[2] & 0x3f;
141 Assert(output[0] < 64);
142 Assert(output[1] < 64);
143 Assert(output[2] < 64);
144 Assert(output[3] < 64);
145
146 if (datalength + 4 > targsize)
147 return (-1);
148 target[datalength++] = Base64[output[0]];
149 target[datalength++] = Base64[output[1]];
150 target[datalength++] = Base64[output[2]];
151 target[datalength++] = Base64[output[3]];
152 }
153
154 /* Now we worry about padding. */
155 if (0 != srclength) {
156 /* Get what's left. */
157 input[0] = input[1] = input[2] = '\0';
158 for (i = 0; i < srclength; i++)
159 input[i] = *src++;
160
161 output[0] = input[0] >> 2;
162 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
163 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
164 Assert(output[0] < 64);
165 Assert(output[1] < 64);
166 Assert(output[2] < 64);
167
168 if (datalength + 4 > targsize)
169 return (-1);
170 target[datalength++] = Base64[output[0]];
171 target[datalength++] = Base64[output[1]];
172 if (srclength == 1)
173 target[datalength++] = Pad64;
174 else
175 target[datalength++] = Base64[output[2]];
176 target[datalength++] = Pad64;
177 }
178 if (datalength >= targsize)
179 return (-1);
180 target[datalength] = '\0'; /* Returned value doesn't count \0. */
181 return (datalength);
182}
183libresolv_hidden_def (b64_ntop)
184
185/* skips all whitespace anywhere.
186 converts characters, four at a time, starting at (or after)
187 src from base - 64 numbers into three 8 bit bytes in the target area.
188 it returns the number of data bytes stored at the target, or -1 on error.
189 */
190
191int
192b64_pton (char const *src, u_char *target, size_t targsize)
193{
194 int tarindex, state, ch;
195 char *pos;
196
197 state = 0;
198 tarindex = 0;
199
200 while ((ch = *src++) != '\0') {
201 if (isspace(ch)) /* Skip whitespace anywhere. */
202 continue;
203
204 if (ch == Pad64)
205 break;
206
207 pos = strchr(s: Base64, c: ch);
208 if (pos == 0) /* A non-base64 character. */
209 return (-1);
210
211 switch (state) {
212 case 0:
213 if (target) {
214 if ((size_t)tarindex >= targsize)
215 return (-1);
216 target[tarindex] = (pos - Base64) << 2;
217 }
218 state = 1;
219 break;
220 case 1:
221 if (target) {
222 if ((size_t)tarindex + 1 >= targsize)
223 return (-1);
224 target[tarindex] |= (pos - Base64) >> 4;
225 target[tarindex+1] = ((pos - Base64) & 0x0f)
226 << 4 ;
227 }
228 tarindex++;
229 state = 2;
230 break;
231 case 2:
232 if (target) {
233 if ((size_t)tarindex + 1 >= targsize)
234 return (-1);
235 target[tarindex] |= (pos - Base64) >> 2;
236 target[tarindex+1] = ((pos - Base64) & 0x03)
237 << 6;
238 }
239 tarindex++;
240 state = 3;
241 break;
242 case 3:
243 if (target) {
244 if ((size_t)tarindex >= targsize)
245 return (-1);
246 target[tarindex] |= (pos - Base64);
247 }
248 tarindex++;
249 state = 0;
250 break;
251 default:
252 abort();
253 }
254 }
255
256 /*
257 * We are done decoding Base-64 chars. Let's see if we ended
258 * on a byte boundary, and/or with erroneous trailing characters.
259 */
260
261 if (ch == Pad64) { /* We got a pad char. */
262 ch = *src++; /* Skip it, get next. */
263 switch (state) {
264 case 0: /* Invalid = in first position */
265 case 1: /* Invalid = in second position */
266 return (-1);
267
268 case 2: /* Valid, means one byte of info */
269 /* Skip any number of spaces. */
270 for ((void)NULL; ch != '\0'; ch = *src++)
271 if (!isspace(ch))
272 break;
273 /* Make sure there is another trailing = sign. */
274 if (ch != Pad64)
275 return (-1);
276 ch = *src++; /* Skip the = */
277 /* Fall through to "single trailing =" case. */
278 /* FALLTHROUGH */
279
280 case 3: /* Valid, means two bytes of info */
281 /*
282 * We know this char is an =. Is there anything but
283 * whitespace after it?
284 */
285 for ((void)NULL; ch != '\0'; ch = *src++)
286 if (!isspace(ch))
287 return (-1);
288
289 /*
290 * Now make sure for cases 2 and 3 that the "extra"
291 * bits that slopped past the last full byte were
292 * zeros. If we don't check them, they become a
293 * subliminal channel.
294 */
295 if (target && target[tarindex] != 0)
296 return (-1);
297 }
298 } else {
299 /*
300 * We ended by seeing the end of the string. Make sure we
301 * have no partial bytes lying around.
302 */
303 if (state != 0)
304 return (-1);
305 }
306
307 return (tarindex);
308}
309

source code of glibc/resolv/base64.c