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base64.c (4085B)
1 #include <string.h>
2 #include <stdlib.h>
3
4 int base64_encode(unsigned char *source, size_t sourcelen, char *target, size_t targetlen);
5 size_t base64_encode_size(size_t sourcelen);
6 void _base64_encode_triple(unsigned char triple[3], char result[4]);
7 int _base64_char_value(char base64char);
8 int _base64_decode_triple(char quadruple[4], unsigned char *result);
9 size_t base64_decode(char *source, unsigned char *target, size_t targetlen);
10 size_t base64_decode_size(char *source);
11
12 const char *BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
13
14 void _base64_encode_triple(unsigned char triple[3], char result[4])
15 {
16 int tripleValue, i;
17
18 tripleValue = triple[0];
19 tripleValue *= 256;
20 tripleValue += triple[1];
21 tripleValue *= 256;
22 tripleValue += triple[2];
23
24 for (i=0; i<4; i++)
25 {
26 result[3-i] = BASE64_CHARS[tripleValue%64];
27 tripleValue /= 64;
28 }
29 }
30
31 int base64_encode(unsigned char *source, size_t sourcelen, char *target, size_t targetlen)
32 {
33 if ((sourcelen+2)/3*4 > targetlen-1)
34 return 0;
35
36 while (sourcelen >= 3)
37 {
38 _base64_encode_triple(source, target);
39 sourcelen -= 3;
40 source += 3;
41 target += 4;
42 }
43
44 if (sourcelen > 0)
45 {
46 unsigned char temp[3];
47 memset(temp, 0, sizeof(temp));
48 memcpy(temp, source, sourcelen);
49 _base64_encode_triple(temp, target);
50 target[3] = '=';
51 if (sourcelen == 1)
52 target[2] = '=';
53
54 target += 4;
55 }
56
57 target[0] = 0;
58
59 return 1;
60 }
61
62 size_t base64_encode_size(size_t sourcelen)
63 {
64 return (sourcelen+2)/3*4+1;
65 }
66
67 int _base64_char_value(char base64char)
68 {
69 if (base64char >= 'A' && base64char <= 'Z')
70 return base64char-'A';
71 if (base64char >= 'a' && base64char <= 'z')
72 return base64char-'a'+26;
73 if (base64char >= '0' && base64char <= '9')
74 return base64char-'0'+2*26;
75 if (base64char == '+')
76 return 2*26+10;
77 if (base64char == '/')
78 return 2*26+11;
79 return -1;
80 }
81
82 int _base64_decode_triple(char quadruple[4], unsigned char *result)
83 {
84 int i, triple_value, bytes_to_decode = 3, only_equals_yet = 1;
85 int char_value[4];
86
87 for (i=0; i<4; i++)
88 char_value[i] = _base64_char_value(quadruple[i]);
89
90 for (i=3; i>=0; i--)
91 {
92 if (char_value[i]<0)
93 {
94 if (only_equals_yet && quadruple[i]=='=')
95 {
96 char_value[i]=0;
97 bytes_to_decode--;
98 continue;
99 }
100 return 0;
101 }
102 only_equals_yet = 0;
103 }
104
105 if (bytes_to_decode < 0)
106 bytes_to_decode = 0;
107
108 triple_value = char_value[0];
109 triple_value *= 64;
110 triple_value += char_value[1];
111 triple_value *= 64;
112 triple_value += char_value[2];
113 triple_value *= 64;
114 triple_value += char_value[3];
115
116 for (i=bytes_to_decode; i<3; i++)
117 triple_value /= 256;
118 for (i=bytes_to_decode-1; i>=0; i--)
119 {
120 result[i] = triple_value%256;
121 triple_value /= 256;
122 }
123
124 return bytes_to_decode;
125 }
126
127 size_t base64_decode(char *source, unsigned char *target, size_t targetlen)
128 {
129 char *src, *tmpptr;
130 char quadruple[4];
131 unsigned char tmpresult[3];
132 int i, tmplen = 3;
133 size_t converted = 0;
134
135 src = (char *)malloc(strlen(source)+5);
136 if (src == NULL)
137 return -1;
138 strcpy(src, source);
139 strcat(src, "====");
140 tmpptr = src;
141
142 while (tmplen == 3)
143 {
144 for (i=0; i<4; i++)
145 {
146 while (*tmpptr != '=' && _base64_char_value(*tmpptr)<0)
147 tmpptr++;
148
149 quadruple[i] = *(tmpptr++);
150 }
151
152 tmplen = _base64_decode_triple(quadruple, tmpresult);
153
154 if (targetlen < tmplen)
155 {
156 free(src);
157 return -1;
158 }
159
160 memcpy(target, tmpresult, tmplen);
161 target += tmplen;
162 targetlen -= tmplen;
163 converted += tmplen;
164 }
165
166 free(src);
167 return converted;
168 }
169
170 size_t base64_decode_size(char *source) {
171
172 if (!source) return -1;
173
174 size_t len = strlen(source);
175
176 if (len < 4) /* invalid base64, minimum is 4 chars */ return -1;
177
178 if (source[len-1] != '=') return len*3/4;
179 if (source[len-2] != '=') return (len-1)*3/4;
180 else return (len-2)*3/4;
181 }
182
183 int checkLibsheepyVersionBase64(const char *currentLibsheepyVersion) {
184 return currentLibsheepyVersion ? 1 : 0;
185 }
186
187 // vim: set expandtab ts=2 sw=2: