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80a47a2c TK |
1 | /* |
2 | * RFC 1521 base64 encoding/decoding | |
3 | * | |
4 | * Based on XySSL: Copyright (C) 2006-2008 Christophe Devine | |
5 | * | |
6 | * Copyright (C) 2009 Paul Bakker <polarssl_maintainer at polarssl dot org> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License along | |
19 | * with this program; if not, write to the Free Software Foundation, Inc., | |
20 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
21 | */ | |
22 | ||
23 | /* $Cambridge: exim/src/src/pdkim/base64.c,v 1.2 2009/06/10 07:34:05 tom Exp $ */ | |
24 | ||
25 | #include "base64.h" | |
26 | ||
27 | static const unsigned char base64_enc_map[64] = | |
28 | { | |
29 | 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', | |
30 | 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', | |
31 | 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', | |
32 | 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', | |
33 | 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', | |
34 | 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', | |
35 | '8', '9', '+', '/' | |
36 | }; | |
37 | ||
38 | static const unsigned char base64_dec_map[128] = | |
39 | { | |
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 | /* | |
56 | * Encode a buffer into base64 format | |
57 | */ | |
58 | int base64_encode( unsigned char *dst, int *dlen, | |
59 | unsigned char *src, int slen ) | |
60 | { | |
61 | int i, n; | |
62 | int C1, C2, C3; | |
63 | unsigned char *p; | |
64 | ||
65 | if( slen == 0 ) | |
66 | return( 0 ); | |
67 | ||
68 | n = (slen << 3) / 6; | |
69 | ||
70 | switch( (slen << 3) - (n * 6) ) | |
71 | { | |
72 | case 2: n += 3; break; | |
73 | case 4: n += 2; break; | |
74 | default: break; | |
75 | } | |
76 | ||
77 | if( *dlen < n + 1 ) | |
78 | { | |
79 | *dlen = n + 1; | |
80 | return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL ); | |
81 | } | |
82 | ||
83 | n = (slen / 3) * 3; | |
84 | ||
85 | for( i = 0, p = dst; i < n; i += 3 ) | |
86 | { | |
87 | C1 = *src++; | |
88 | C2 = *src++; | |
89 | C3 = *src++; | |
90 | ||
91 | *p++ = base64_enc_map[(C1 >> 2) & 0x3F]; | |
92 | *p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F]; | |
93 | *p++ = base64_enc_map[(((C2 & 15) << 2) + (C3 >> 6)) & 0x3F]; | |
94 | *p++ = base64_enc_map[C3 & 0x3F]; | |
95 | } | |
96 | ||
97 | if( i < slen ) | |
98 | { | |
99 | C1 = *src++; | |
100 | C2 = ((i + 1) < slen) ? *src++ : 0; | |
101 | ||
102 | *p++ = base64_enc_map[(C1 >> 2) & 0x3F]; | |
103 | *p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F]; | |
104 | ||
105 | if( (i + 1) < slen ) | |
106 | *p++ = base64_enc_map[((C2 & 15) << 2) & 0x3F]; | |
107 | else *p++ = '='; | |
108 | ||
109 | *p++ = '='; | |
110 | } | |
111 | ||
112 | *dlen = p - dst; | |
113 | *p = 0; | |
114 | ||
115 | return( 0 ); | |
116 | } | |
117 | ||
118 | /* | |
119 | * Decode a base64-formatted buffer | |
120 | */ | |
121 | int base64_decode( unsigned char *dst, int *dlen, | |
122 | unsigned char *src, int slen ) | |
123 | { | |
124 | int i, j, n; | |
125 | unsigned long x; | |
126 | unsigned char *p; | |
127 | ||
128 | for( i = j = n = 0; i < slen; i++ ) | |
129 | { | |
130 | if( ( slen - i ) >= 2 && | |
131 | src[i] == '\r' && src[i + 1] == '\n' ) | |
132 | continue; | |
133 | ||
134 | if( src[i] == '\n' ) | |
135 | continue; | |
136 | ||
137 | if( src[i] == '=' && ++j > 2 ) | |
138 | return( POLARSSL_ERR_BASE64_INVALID_CHARACTER ); | |
139 | ||
140 | if( src[i] > 127 || base64_dec_map[src[i]] == 127 ) | |
141 | return( POLARSSL_ERR_BASE64_INVALID_CHARACTER ); | |
142 | ||
143 | if( base64_dec_map[src[i]] < 64 && j != 0 ) | |
144 | return( POLARSSL_ERR_BASE64_INVALID_CHARACTER ); | |
145 | ||
146 | n++; | |
147 | } | |
148 | ||
149 | if( n == 0 ) | |
150 | return( 0 ); | |
151 | ||
152 | n = ((n * 6) + 7) >> 3; | |
153 | ||
154 | if( *dlen < n ) | |
155 | { | |
156 | *dlen = n; | |
157 | return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL ); | |
158 | } | |
159 | ||
160 | for( j = 3, n = x = 0, p = dst; i > 0; i--, src++ ) | |
161 | { | |
162 | if( *src == '\r' || *src == '\n' ) | |
163 | continue; | |
164 | ||
165 | j -= ( base64_dec_map[*src] == 64 ); | |
166 | x = (x << 6) | ( base64_dec_map[*src] & 0x3F ); | |
167 | ||
168 | if( ++n == 4 ) | |
169 | { | |
170 | n = 0; | |
171 | if( j > 0 ) *p++ = (unsigned char)( x >> 16 ); | |
172 | if( j > 1 ) *p++ = (unsigned char)( x >> 8 ); | |
173 | if( j > 2 ) *p++ = (unsigned char)( x ); | |
174 | } | |
175 | } | |
176 | ||
177 | *dlen = p - dst; | |
178 | ||
179 | return( 0 ); | |
180 | } |