1 /*
2
3 This code is public domain software.
4
5 */
6
7 #include "base64.h"
8
9 #include <stdlib.h>
10 #include <string.h>
11
12 // base64 encoding
13 //
14 // buf: binary input data
15 // size: size of input (bytes)
16 // return: base64-encoded string (null-terminated)
17 // memory for output will be allocated here, free it later
18 //
base64_encode(const void * buf,size_t size)19 char* base64_encode(const void* buf, size_t size)
20 {
21 static const char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
22
23 char* str = (char*) malloc((size+3)*4/3 + 1);
24
25 char* p = str;
26 const unsigned char* q = (const unsigned char*) buf;
27 size_t i = 0;
28
29 if (str == NULL) {
30 return NULL;
31 }
32
33 while (i < size) {
34 int c = q[i++];
35 c *= 256;
36 if (i < size)
37 c += q[i];
38 i++;
39
40 c *= 256;
41 if (i < size)
42 c += q[i];
43 i++;
44
45 *p++ = base64[(c & 0x00fc0000) >> 18];
46 *p++ = base64[(c & 0x0003f000) >> 12];
47
48 if (i > size + 1)
49 *p++ = '=';
50 else
51 *p++ = base64[(c & 0x00000fc0) >> 6];
52
53 if (i > size)
54 *p++ = '=';
55 else
56 *p++ = base64[c & 0x0000003f];
57 }
58
59 *p = 0;
60
61 return str;
62 }
63
64
65 // single base64 character conversion
66 //
POS(char c)67 static int POS(char c)
68 {
69 if (c>='A' && c<='Z') return c - 'A';
70 if (c>='a' && c<='z') return c - 'a' + 26;
71 if (c>='0' && c<='9') return c - '0' + 52;
72 if (c == '+') return 62;
73 if (c == '/') return 63;
74 if (c == '=') return -1;
75 return -2;
76 }
77
78 // base64 decoding
79 //
80 // s: base64 string, must be null-terminated
81 // data: output buffer for decoded data
82 // data_len size of decoded data
83 // return: allocated data buffer
84 //
base64_decode(const char * s,size_t * data_len)85 void* base64_decode(const char* s, size_t *data_len)
86 {
87 const char *p;
88 unsigned char *q, *data;
89 int n[4] = { 0, 0, 0, 0 };
90
91 size_t len = strlen(s);
92 if (len % 4)
93 return NULL;
94 data = (unsigned char*) malloc(len/4*3);
95 q = (unsigned char*) data;
96
97 for (p = s; *p; ) {
98 n[0] = POS(*p++);
99 n[1] = POS(*p++);
100 n[2] = POS(*p++);
101 n[3] = POS(*p++);
102
103 if (n[0] == -2 || n[1] == -2 || n[2] == -2 || n[3] == -2)
104 return NULL;
105
106 if (n[0] == -1 || n[1] == -1)
107 return NULL;
108
109 if (n[2] == -1 && n[3] != -1)
110 return NULL;
111
112 q[0] = (n[0] << 2) + (n[1] >> 4);
113 if (n[2] != -1)
114 q[1] = ((n[1] & 15) << 4) + (n[2] >> 2);
115 if (n[3] != -1)
116 q[2] = ((n[2] & 3) << 6) + n[3];
117 q += 3;
118 }
119
120 *data_len = q-data - (n[2]==-1) - (n[3]==-1);
121
122 return data;
123 }
124