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 int
ldns_b64_ntop(uint8_t const * src,size_t srclength,char * target,size_t targsize)115 ldns_b64_ntop(uint8_t const *src, size_t srclength, char *target, size_t targsize) {
116 size_t datalength = 0;
117 uint8_t input[3];
118 uint8_t output[4];
119 size_t i;
120
121 if (srclength == 0) {
122 if (targsize > 0) {
123 target[0] = '\0';
124 return 0;
125 } else {
126 return -1;
127 }
128 }
129
130 while (2 < srclength) {
131 input[0] = *src++;
132 input[1] = *src++;
133 input[2] = *src++;
134 srclength -= 3;
135
136 output[0] = input[0] >> 2;
137 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
138 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
139 output[3] = input[2] & 0x3f;
140 assert(output[0] < 64);
141 assert(output[1] < 64);
142 assert(output[2] < 64);
143 assert(output[3] < 64);
144
145 if (datalength + 4 > targsize) {
146 return (-1);
147 }
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] = (uint8_t) '\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 (-2);
170 }
171 target[datalength++] = Base64[output[0]];
172 target[datalength++] = Base64[output[1]];
173 if (srclength == 1) {
174 target[datalength++] = Pad64;
175 } else {
176 target[datalength++] = Base64[output[2]];
177 }
178 target[datalength++] = Pad64;
179 }
180 if (datalength >= targsize) {
181 return (-3);
182 }
183 target[datalength] = '\0'; /* Returned value doesn't count \0. */
184 return (int) (datalength);
185 }
186