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1 /*
2 * Base64 encoding/decoding (RFC1341)
3 * Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>
4 * Modified by Dormando
5 *
6 * This software may be distributed under the terms of the BSD license.
7 * Original license included below:
8 *
9 License
10 -------
11
12 This software may be distributed, used, and modified under the terms of
13 BSD license:
14
15 Redistribution and use in source and binary forms, with or without
16 modification, are permitted provided that the following conditions are
17 met:
18
19 1. Redistributions of source code must retain the above copyright
20 notice, this list of conditions and the following disclaimer.
21
22 2. Redistributions in binary form must reproduce the above copyright
23 notice, this list of conditions and the following disclaimer in the
24 documentation and/or other materials provided with the distribution.
25
26 3. Neither the name(s) of the above-listed copyright holder(s) nor the
27 names of its contributors may be used to endorse or promote products
28 derived from this software without specific prior written permission.
29
30 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
31 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
32 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
33 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
34 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
36 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
37 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
38 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
39 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
40 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41 */
42
43 /* Changes from original code:
44 * - decode table is pre-generated
45 * - no line splitting on encoder
46 * - output buffers are passed in instead of malloc'ed
47 * - returns encoded/decoded length instead of pointer.
48 */
49
50 #include <stddef.h>
51 #include "base64.h"
52
53 static const unsigned char base64_table[65] =
54 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
55
56 /* Original decode function generated the table every time. I used the code to
57 * print this table and pre-generate it instead.
58 */
59 static const unsigned char dtable[256] = {
60 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
61 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
62 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
63 62, 128, 128, 128, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60,
64 61, 128, 128, 128, 0, 128, 128, 128, 0, 1, 2, 3, 4, 5,
65 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
66 20, 21, 22, 23, 24, 25, 128, 128, 128, 128, 128, 128, 26, 27,
67 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,
68 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 128, 128, 128, 128,
69 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
70 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
71 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
72 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
73 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
74 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
75 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
76 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
77 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
78 128, 128, 128
79 };
80
81 /**
82 * base64_encode - Base64 encode
83 * @src: Data to be encoded
84 * @len: Length of the data to be encoded
85 * @out: output uffer
86 * @out_len: length of output buffer
87 * Returns: Number of actual bytes encoded into the buffer
88 * or 0 on failure
89 *
90 * Output buffer is nul terminated to make it easier to use as a C string.
91 * The nul terminator is * not included in the return length.
92 */
93 size_t base64_encode(const unsigned char *src, size_t len,
94 unsigned char *out, size_t out_len)
95 {
96 unsigned char *pos;
97 const unsigned char *end, *in;
98 size_t olen;
99
100 olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
101 olen += olen / 72; /* line feeds */
102 olen++; /* nul termination */
103 if (olen < len) {
104 return 0; /* integer overflow */
105 }
106 if (olen > out_len) {
107 return 0; /* not enough space in output buffer */
108 }
109 if (out == NULL) {
110 return 0;
111 }
112
113 end = src + len;
114 in = src;
115 pos = out;
116 while (end - in >= 3) {
117 *pos++ = base64_table[in[0] >> 2];
118 *pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
119 *pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
120 *pos++ = base64_table[in[2] & 0x3f];
121 in += 3;
122 }
123
124 if (end - in) {
125 *pos++ = base64_table[in[0] >> 2];
126 if (end - in == 1) {
127 *pos++ = base64_table[(in[0] & 0x03) << 4];
128 *pos++ = '=';
129 } else {
130 *pos++ = base64_table[((in[0] & 0x03) << 4) |
131 (in[1] >> 4)];
132 *pos++ = base64_table[(in[1] & 0x0f) << 2];
133 }
134 *pos++ = '=';
135 }
136
137 *pos = '\0';
138 return pos - out;
139 }
140
141
142 /**
143 * base64_decode - Base64 decode
144 * @src: Data to be decoded
145 * @len: Length of the data to be decoded
146 * @out: Output buffer to decode into
147 * @out_len: Length of output buffer
148 * Returns: Length of encoded data, or 0 on failure
149 */
150 size_t base64_decode(const unsigned char *src, size_t len,
151 unsigned char *out, size_t out_len)
152 {
153 unsigned char *pos, block[4], tmp;
154 size_t i, count, olen;
155 int pad = 0;
156
157 count = 0;
158 for (i = 0; i < len; i++) {
159 if (dtable[src[i]] != 0x80)
160 count++;
161 }
162
163 if (count == 0 || count % 4)
164 return 0;
165
166 olen = count / 4 * 3;
167 if (olen > out_len) {
168 return 0;
169 }
170 pos = out;
171 if (out == NULL) {
172 return 0;
173 }
174
175 count = 0;
176 for (i = 0; i < len; i++) {
177 tmp = dtable[src[i]];
178 if (tmp == 0x80)
179 continue;
180
181 if (src[i] == '=')
182 pad++;
183 block[count] = tmp;
184 count++;
185 if (count == 4) {
186 *pos++ = (block[0] << 2) | (block[1] >> 4);
187 *pos++ = (block[1] << 4) | (block[2] >> 2);
188 *pos++ = (block[2] << 6) | block[3];
189 count = 0;
190 if (pad) {
191 if (pad == 1)
192 pos--;
193 else if (pad == 2)
194 pos -= 2;
195 else {
196 /* Invalid padding */
197 return 0;
198 }
199 break;
200 }
201 }
202 }
203
204 return pos - out;
205 }