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 #include <sys/types.h>
44 #include <sys/param.h>
45 #include <sys/socket.h>
46
47 #include <netinet/in.h>
48 #include <arpa/inet.h>
49
50 #include <ctype.h>
51 #include <stdio.h>
52 #include <stdlib.h>
53 #include <string.h>
54
55 #define Assert(Cond) if (!(Cond)) abort()
56
57 static const char Base64[] =
58 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
59 static 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
124 int
b64_ntop(uint8_t const * src,size_t srclength,char * target,size_t targsize)125 b64_ntop(uint8_t const *src, size_t srclength, char *target, size_t targsize) {
126 size_t datalength = 0;
127 uint8_t input[3];
128 uint8_t 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 }
183