1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
// SPDX-License-Identifier: GPL-2.0
/*
* base64.c - Base64 with support for multiple variants
*
* Copyright (c) 2020 Hannes Reinecke, SUSE
*
* Based on the base64url routines from fs/crypto/fname.c
* (which are using the URL-safe Base64 encoding),
* modified to support multiple Base64 variants.
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/export.h>
#include <linux/string.h>
#include <linux/base64.h>
static const char base64_tables[][65] = {
[BASE64_STD] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
[BASE64_URLSAFE] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_",
[BASE64_IMAP] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,",
};
/*
* Initialize the base64 reverse mapping for a single character
* This macro maps a character to its corresponding base64 value,
* returning -1 if the character is invalid.
* char 'A'-'Z' maps to 0-25, 'a'-'z' maps to 26-51, '0'-'9' maps to 52-61,
* ch_62 maps to 62, ch_63 maps to 63, and other characters return -1
*/
#define INIT_1(v, ch_62, ch_63) \
[v] = (v) >= 'A' && (v) <= 'Z' ? (v) - 'A' \
: (v) >= 'a' && (v) <= 'z' ? (v) - 'a' + 26 \
: (v) >= '0' && (v) <= '9' ? (v) - '0' + 52 \
: (v) == (ch_62) ? 62 : (v) == (ch_63) ? 63 : -1
/*
* Recursive macros to generate multiple Base64 reverse mapping table entries.
* Each macro generates a sequence of entries in the lookup table:
* INIT_2 generates 2 entries, INIT_4 generates 4, INIT_8 generates 8, and so on up to INIT_32.
*/
#define INIT_2(v, ...) INIT_1(v, __VA_ARGS__), INIT_1((v) + 1, __VA_ARGS__)
#define INIT_4(v, ...) INIT_2(v, __VA_ARGS__), INIT_2((v) + 2, __VA_ARGS__)
#define INIT_8(v, ...) INIT_4(v, __VA_ARGS__), INIT_4((v) + 4, __VA_ARGS__)
#define INIT_16(v, ...) INIT_8(v, __VA_ARGS__), INIT_8((v) + 8, __VA_ARGS__)
#define INIT_32(v, ...) INIT_16(v, __VA_ARGS__), INIT_16((v) + 16, __VA_ARGS__)
#define BASE64_REV_INIT(ch_62, ch_63) { \
[0 ... 0x1f] = -1, \
INIT_32(0x20, ch_62, ch_63), \
INIT_32(0x40, ch_62, ch_63), \
INIT_32(0x60, ch_62, ch_63), \
[0x80 ... 0xff] = -1 }
static const s8 base64_rev_maps[][256] = {
[BASE64_STD] = BASE64_REV_INIT('+', '/'),
[BASE64_URLSAFE] = BASE64_REV_INIT('-', '_'),
[BASE64_IMAP] = BASE64_REV_INIT('+', ',')
};
#undef BASE64_REV_INIT
#undef INIT_32
#undef INIT_16
#undef INIT_8
#undef INIT_4
#undef INIT_2
#undef INIT_1
/**
* base64_encode() - Base64-encode some binary data
* @src: the binary data to encode
* @srclen: the length of @src in bytes
* @dst: (output) the Base64-encoded string. Not NUL-terminated.
* @padding: whether to append '=' padding characters
* @variant: which base64 variant to use
*
* Encodes data using the selected Base64 variant.
*
* Return: the length of the resulting Base64-encoded string in bytes.
*/
int base64_encode(const u8 *src, int srclen, char *dst, bool padding, enum base64_variant variant)
{
u32 ac = 0;
char *cp = dst;
const char *base64_table = base64_tables[variant];
while (srclen >= 3) {
ac = src[0] << 16 | src[1] << 8 | src[2];
*cp++ = base64_table[ac >> 18];
*cp++ = base64_table[(ac >> 12) & 0x3f];
*cp++ = base64_table[(ac >> 6) & 0x3f];
*cp++ = base64_table[ac & 0x3f];
src += 3;
srclen -= 3;
}
switch (srclen) {
case 2:
ac = src[0] << 16 | src[1] << 8;
*cp++ = base64_table[ac >> 18];
*cp++ = base64_table[(ac >> 12) & 0x3f];
*cp++ = base64_table[(ac >> 6) & 0x3f];
if (padding)
*cp++ = '=';
break;
case 1:
ac = src[0] << 16;
*cp++ = base64_table[ac >> 18];
*cp++ = base64_table[(ac >> 12) & 0x3f];
if (padding) {
*cp++ = '=';
*cp++ = '=';
}
break;
}
return cp - dst;
}
EXPORT_SYMBOL_GPL(base64_encode);
/**
* base64_decode() - Base64-decode a string
* @src: the string to decode. Doesn't need to be NUL-terminated.
* @srclen: the length of @src in bytes
* @dst: (output) the decoded binary data
* @padding: whether to append '=' padding characters
* @variant: which base64 variant to use
*
* Decodes a string using the selected Base64 variant.
*
* Return: the length of the resulting decoded binary data in bytes,
* or -1 if the string isn't a valid Base64 string.
*/
int base64_decode(const char *src, int srclen, u8 *dst, bool padding, enum base64_variant variant)
{
u8 *bp = dst;
s8 input[4];
s32 val;
const u8 *s = (const u8 *)src;
const s8 *base64_rev_tables = base64_rev_maps[variant];
while (srclen >= 4) {
input[0] = base64_rev_tables[s[0]];
input[1] = base64_rev_tables[s[1]];
input[2] = base64_rev_tables[s[2]];
input[3] = base64_rev_tables[s[3]];
val = input[0] << 18 | input[1] << 12 | input[2] << 6 | input[3];
if (unlikely(val < 0)) {
if (!padding || srclen != 4 || s[3] != '=')
return -1;
padding = 0;
srclen = s[2] == '=' ? 2 : 3;
break;
}
*bp++ = val >> 16;
*bp++ = val >> 8;
*bp++ = val;
s += 4;
srclen -= 4;
}
if (likely(!srclen))
return bp - dst;
if (padding || srclen == 1)
return -1;
val = (base64_rev_tables[s[0]] << 12) | (base64_rev_tables[s[1]] << 6);
*bp++ = val >> 10;
if (srclen == 2) {
if (val & 0x800003ff)
return -1;
} else {
val |= base64_rev_tables[s[2]];
if (val & 0x80000003)
return -1;
*bp++ = val >> 2;
}
return bp - dst;
}
EXPORT_SYMBOL_GPL(base64_decode);
|
