1 /*
2 * Base64 encoding/decoding (RFC1341)
3 * Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9 #include "includes.h"
10
11 #include "os.h"
12 #include "base64.h"
13
14 static const unsigned char base64_table[65] =
15 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
16
17 /**
18 * base64_encode - Base64 encode
19 * @src: Data to be encoded
20 * @len: Length of the data to be encoded
21 * @out_len: Pointer to output length variable, or %NULL if not used
22 * Returns: Allocated buffer of out_len bytes of encoded data,
23 * or %NULL on failure
24 *
25 * Caller is responsible for freeing the returned buffer. Returned buffer is
26 * nul terminated to make it easier to use as a C string. The nul terminator is
27 * not included in out_len.
28 */
base64_encode(const unsigned char * src,size_t len,size_t * out_len)29 unsigned char * base64_encode(const unsigned char *src, size_t len,
30 size_t *out_len)
31 {
32 unsigned char *out, *pos;
33 const unsigned char *end, *in;
34 size_t olen;
35 int line_len;
36
37 olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
38 olen += olen / 72; /* line feeds */
39 olen++; /* nul termination */
40 if (olen < len)
41 return NULL; /* integer overflow */
42 out = os_malloc(olen);
43 if (out == NULL)
44 return NULL;
45
46 end = src + len;
47 in = src;
48 pos = out;
49 line_len = 0;
50 while (end - in >= 3) {
51 *pos++ = base64_table[(in[0] >> 2) & 0x3f];
52 *pos++ = base64_table[(((in[0] & 0x03) << 4) |
53 (in[1] >> 4)) & 0x3f];
54 *pos++ = base64_table[(((in[1] & 0x0f) << 2) |
55 (in[2] >> 6)) & 0x3f];
56 *pos++ = base64_table[in[2] & 0x3f];
57 in += 3;
58 line_len += 4;
59 if (line_len >= 72) {
60 *pos++ = '\n';
61 line_len = 0;
62 }
63 }
64
65 if (end - in) {
66 *pos++ = base64_table[(in[0] >> 2) & 0x3f];
67 if (end - in == 1) {
68 *pos++ = base64_table[((in[0] & 0x03) << 4) & 0x3f];
69 *pos++ = '=';
70 } else {
71 *pos++ = base64_table[(((in[0] & 0x03) << 4) |
72 (in[1] >> 4)) & 0x3f];
73 *pos++ = base64_table[((in[1] & 0x0f) << 2) & 0x3f];
74 }
75 *pos++ = '=';
76 line_len += 4;
77 }
78
79 if (line_len)
80 *pos++ = '\n';
81
82 *pos = '\0';
83 if (out_len)
84 *out_len = pos - out;
85 return out;
86 }
87
88
89 /**
90 * base64_decode - Base64 decode
91 * @src: Data to be decoded
92 * @len: Length of the data to be decoded
93 * @out_len: Pointer to output length variable
94 * Returns: Allocated buffer of out_len bytes of decoded data,
95 * or %NULL on failure
96 *
97 * Caller is responsible for freeing the returned buffer.
98 */
base64_decode(const unsigned char * src,size_t len,size_t * out_len)99 unsigned char * base64_decode(const unsigned char *src, size_t len,
100 size_t *out_len)
101 {
102 unsigned char dtable[256], *out, *pos, block[4], tmp;
103 size_t i, count, olen;
104 int pad = 0;
105
106 os_memset(dtable, 0x80, 256);
107 for (i = 0; i < sizeof(base64_table) - 1; i++)
108 dtable[base64_table[i]] = (unsigned char) i;
109 dtable['='] = 0;
110
111 count = 0;
112 for (i = 0; i < len; i++) {
113 if (dtable[src[i]] != 0x80)
114 count++;
115 }
116
117 if (count == 0 || count % 4)
118 return NULL;
119
120 olen = count / 4 * 3;
121 pos = out = os_malloc(olen);
122 if (out == NULL)
123 return NULL;
124
125 count = 0;
126 for (i = 0; i < len; i++) {
127 tmp = dtable[src[i]];
128 if (tmp == 0x80)
129 continue;
130
131 if (src[i] == '=')
132 pad++;
133 block[count] = tmp;
134 count++;
135 if (count == 4) {
136 *pos++ = (block[0] << 2) | (block[1] >> 4);
137 *pos++ = (block[1] << 4) | (block[2] >> 2);
138 *pos++ = (block[2] << 6) | block[3];
139 count = 0;
140 if (pad) {
141 if (pad == 1)
142 pos--;
143 else if (pad == 2)
144 pos -= 2;
145 else {
146 /* Invalid padding */
147 os_free(out);
148 return NULL;
149 }
150 break;
151 }
152 }
153 }
154
155 *out_len = pos - out;
156 return out;
157 }
158