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 #include <ldns/config.h>
43 #include <ctype.h>
44 #include <stdlib.h>
45 #include <string.h>
46
47 static const char Base64[] =
48 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
49 static const char Pad64 = '=';
50
51 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
52 The following encoding technique is taken from RFC 1521 by Borenstein
53 and Freed. It is reproduced here in a slightly edited form for
54 convenience.
55
56 A 65-character subset of US-ASCII is used, enabling 6 bits to be
57 represented per printable character. (The extra 65th character, "=",
58 is used to signify a special processing function.)
59
60 The encoding process represents 24-bit groups of input bits as output
61 strings of 4 encoded characters. Proceeding from left to right, a
62 24-bit input group is formed by concatenating 3 8-bit input groups.
63 These 24 bits are then treated as 4 concatenated 6-bit groups, each
64 of which is translated into a single digit in the base64 alphabet.
65
66 Each 6-bit group is used as an index into an array of 64 printable
67 characters. The character referenced by the index is placed in the
68 output string.
69
70 Table 1: The Base64 Alphabet
71
72 Value Encoding Value Encoding Value Encoding Value Encoding
73 0 A 17 R 34 i 51 z
74 1 B 18 S 35 j 52 0
75 2 C 19 T 36 k 53 1
76 3 D 20 U 37 l 54 2
77 4 E 21 V 38 m 55 3
78 5 F 22 W 39 n 56 4
79 6 G 23 X 40 o 57 5
80 7 H 24 Y 41 p 58 6
81 8 I 25 Z 42 q 59 7
82 9 J 26 a 43 r 60 8
83 10 K 27 b 44 s 61 9
84 11 L 28 c 45 t 62 +
85 12 M 29 d 46 u 63 /
86 13 N 30 e 47 v
87 14 O 31 f 48 w (pad) =
88 15 P 32 g 49 x
89 16 Q 33 h 50 y
90
91 Special processing is performed if fewer than 24 bits are available
92 at the end of the data being encoded. A full encoding quantum is
93 always completed at the end of a quantity. When fewer than 24 input
94 bits are available in an input group, zero bits are added (on the
95 right) to form an integral number of 6-bit groups. Padding at the
96 end of the data is performed using the '=' character.
97
98 Since all base64 input is an integral number of octets, only the
99 -------------------------------------------------
100 following cases can arise:
101
102 (1) the final quantum of encoding input is an integral
103 multiple of 24 bits; here, the final unit of encoded
104 output will be an integral multiple of 4 characters
105 with no "=" padding,
106 (2) the final quantum of encoding input is exactly 8 bits;
107 here, the final unit of encoded output will be two
108 characters followed by two "=" padding characters, or
109 (3) the final quantum of encoding input is exactly 16 bits;
110 here, the final unit of encoded output will be three
111 characters followed by one "=" padding character.
112 */
113
114 /* skips all whitespace anywhere.
115 converts characters, four at a time, starting at (or after)
116 src from base - 64 numbers into three 8 bit bytes in the target area.
117 it returns the number of data bytes stored at the target, or -1 on error.
118 */
119
120 int
ldns_b64_pton(char const * origsrc,uint8_t * target,size_t targsize)121 ldns_b64_pton(char const *origsrc, uint8_t *target, size_t targsize)
122 {
123 unsigned char const* src = (unsigned char*)origsrc;
124 int tarindex, state, ch;
125 char *pos;
126
127 state = 0;
128 tarindex = 0;
129
130 if (strlen(origsrc) == 0) {
131 return 0;
132 }
133
134 while ((ch = *src++) != '\0') {
135 if (isspace((unsigned char)ch)) /* Skip whitespace anywhere. */
136 continue;
137
138 if (ch == Pad64)
139 break;
140
141 pos = strchr(Base64, ch);
142 if (pos == 0) {
143 /* A non-base64 character. */
144 return (-1);
145 }
146
147 switch (state) {
148 case 0:
149 if (target) {
150 if ((size_t)tarindex >= targsize)
151 return (-1);
152 target[tarindex] = (pos - Base64) << 2;
153 }
154 state = 1;
155 break;
156 case 1:
157 if (target) {
158 if ((size_t)tarindex + 1 >= targsize)
159 return (-1);
160 target[tarindex] |= (pos - Base64) >> 4;
161 target[tarindex+1] = ((pos - Base64) & 0x0f)
162 << 4 ;
163 }
164 tarindex++;
165 state = 2;
166 break;
167 case 2:
168 if (target) {
169 if ((size_t)tarindex + 1 >= targsize)
170 return (-1);
171 target[tarindex] |= (pos - Base64) >> 2;
172 target[tarindex+1] = ((pos - Base64) & 0x03)
173 << 6;
174 }
175 tarindex++;
176 state = 3;
177 break;
178 case 3:
179 if (target) {
180 if ((size_t)tarindex >= targsize)
181 return (-1);
182 target[tarindex] |= (pos - Base64);
183 }
184 tarindex++;
185 state = 0;
186 break;
187 default:
188 abort();
189 }
190 }
191
192 /*
193 * We are done decoding Base-64 chars. Let's see if we ended
194 * on a byte boundary, and/or with erroneous trailing characters.
195 */
196
197 if (ch == Pad64) { /* We got a pad char. */
198 ch = *src++; /* Skip it, get next. */
199 switch (state) {
200 case 0: /* Invalid = in first position */
201 case 1: /* Invalid = in second position */
202 return (-1);
203
204 case 2: /* Valid, means one byte of info */
205 /* Skip any number of spaces. */
206 for ((void)NULL; ch != '\0'; ch = *src++)
207 if (!isspace((unsigned char)ch))
208 break;
209 /* Make sure there is another trailing = sign. */
210 if (ch != Pad64)
211 return (-1);
212 ch = *src++; /* Skip the = */
213 /* Fall through to "single trailing =" case. */
214 /* FALLTHROUGH */
215
216 case 3: /* Valid, means two bytes of info */
217 /*
218 * We know this char is an =. Is there anything but
219 * whitespace after it?
220 */
221 for ((void)NULL; ch != '\0'; ch = *src++)
222 if (!isspace((unsigned char)ch))
223 return (-1);
224
225 /*
226 * Now make sure for cases 2 and 3 that the "extra"
227 * bits that slopped past the last full byte were
228 * zeros. If we don't check them, they become a
229 * subliminal channel.
230 */
231 if (target && target[tarindex] != 0)
232 return (-1);
233 }
234 } else {
235 /*
236 * We ended by seeing the end of the string. Make sure we
237 * have no partial bytes lying around.
238 */
239 if (state != 0)
240 return (-1);
241 }
242
243 return (tarindex);
244 }
245