1 /*
2 * RFC 1521 base64 encoding/decoding
3 *
4 * Copyright (C) 2018, Nordic Semiconductor ASA
5 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
6 * SPDX-License-Identifier: Apache-2.0
7 *
8 * Licensed under the Apache License, Version 2.0 (the "License"); you may
9 * not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
16 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 *
20 * Adapted for Zephyr by Carles Cufi (carles.cufi@nordicsemi.no)
21 * - Removed mbedtls_ prefixes
22 * - Reworked coding style
23 */
24
25 #include <stdint.h>
26 #include <errno.h>
27 #include <sys/base64.h>
28
29 static const uint8_t base64_enc_map[64] = {
30 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
31 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
32 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
33 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
34 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
35 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
36 '8', '9', '+', '/'
37 };
38
39 static const uint8_t base64_dec_map[128] = {
40 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
41 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
42 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
43 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
44 127, 127, 127, 62, 127, 127, 127, 63, 52, 53,
45 54, 55, 56, 57, 58, 59, 60, 61, 127, 127,
46 127, 64, 127, 127, 127, 0, 1, 2, 3, 4,
47 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
48 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
49 25, 127, 127, 127, 127, 127, 127, 26, 27, 28,
50 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
51 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
52 49, 50, 51, 127, 127, 127, 127, 127
53 };
54
55 #define BASE64_SIZE_T_MAX ((size_t) -1) /* SIZE_T_MAX is not standard */
56
57 /*
58 * Encode a buffer into base64 format
59 */
base64_encode(uint8_t * dst,size_t dlen,size_t * olen,const uint8_t * src,size_t slen)60 int base64_encode(uint8_t *dst, size_t dlen, size_t *olen, const uint8_t *src,
61 size_t slen)
62 {
63 size_t i, n;
64 int C1, C2, C3;
65 uint8_t *p;
66
67 if (slen == 0) {
68 *olen = 0;
69 return 0;
70 }
71
72 n = slen / 3 + (slen % 3 != 0);
73
74 if (n > (BASE64_SIZE_T_MAX - 1) / 4) {
75 *olen = BASE64_SIZE_T_MAX;
76 return -ENOMEM;
77 }
78
79 n *= 4;
80
81 if ((dlen < n + 1) || (!dst)) {
82 *olen = n + 1;
83 return -ENOMEM;
84 }
85
86 n = (slen / 3) * 3;
87
88 for (i = 0, p = dst; i < n; i += 3) {
89 C1 = *src++;
90 C2 = *src++;
91 C3 = *src++;
92
93 *p++ = base64_enc_map[(C1 >> 2) & 0x3F];
94 *p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
95 *p++ = base64_enc_map[(((C2 & 15) << 2) + (C3 >> 6)) & 0x3F];
96 *p++ = base64_enc_map[C3 & 0x3F];
97 }
98
99 if (i < slen) {
100 C1 = *src++;
101 C2 = ((i + 1) < slen) ? *src++ : 0;
102
103 *p++ = base64_enc_map[(C1 >> 2) & 0x3F];
104 *p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
105
106 if ((i + 1) < slen) {
107 *p++ = base64_enc_map[((C2 & 15) << 2) & 0x3F];
108 } else {
109 *p++ = '=';
110 }
111
112 *p++ = '=';
113 }
114
115 *olen = p - dst;
116 *p = 0U;
117
118 return 0;
119 }
120
121 /*
122 * Decode a base64-formatted buffer
123 */
base64_decode(uint8_t * dst,size_t dlen,size_t * olen,const uint8_t * src,size_t slen)124 int base64_decode(uint8_t *dst, size_t dlen, size_t *olen, const uint8_t *src,
125 size_t slen)
126 {
127 size_t i, n;
128 uint32_t j, x;
129 uint8_t *p;
130
131 /* First pass: check for validity and get output length */
132 for (i = n = j = 0U; i < slen; i++) {
133 /* Skip spaces before checking for EOL */
134 x = 0U;
135 while (i < slen && src[i] == ' ') {
136 ++i;
137 ++x;
138 }
139
140 /* Spaces at end of buffer are OK */
141 if (i == slen) {
142 break;
143 }
144
145 if ((slen - i) >= 2 && src[i] == '\r' && src[i + 1] == '\n') {
146 continue;
147 }
148
149 if (src[i] == '\n') {
150 continue;
151 }
152
153 /* Space inside a line is an error */
154 if (x != 0U) {
155 return -EINVAL;
156 }
157
158 if (src[i] == '=' && ++j > 2) {
159 return -EINVAL;
160 }
161
162 if (src[i] > 127 || base64_dec_map[src[i]] == 127U) {
163 return -EINVAL;
164 }
165
166 if (base64_dec_map[src[i]] < 64 && j != 0U) {
167 return -EINVAL;
168 }
169
170 n++;
171 }
172
173 if (n == 0) {
174 *olen = 0;
175 return 0;
176 }
177
178 /* The following expression is to calculate the following formula
179 * without risk of integer overflow in n:
180 * n = ( ( n * 6 ) + 7 ) >> 3;
181 */
182 n = (6 * (n >> 3)) + ((6 * (n & 0x7) + 7) >> 3);
183 n -= j;
184
185 if (dst == NULL || dlen < n) {
186 *olen = n;
187 return -ENOMEM;
188 }
189
190 for (j = 3U, n = x = 0U, p = dst; i > 0; i--, src++) {
191
192 if (*src == '\r' || *src == '\n' || *src == ' ') {
193 continue;
194 }
195
196 j -= (base64_dec_map[*src] == 64U);
197 x = (x << 6) | (base64_dec_map[*src] & 0x3F);
198
199 if (++n == 4) {
200 n = 0;
201 if (j > 0) {
202 *p++ = (unsigned char)(x >> 16);
203 }
204 if (j > 1) {
205 *p++ = (unsigned char)(x >> 8);
206 }
207 if (j > 2) {
208 *p++ = (unsigned char)(x);
209 }
210 }
211 }
212
213 *olen = p - dst;
214
215 return 0;
216 }
217
