YAZ  5.23.1
base64.c
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1 /* This file is part of the YAZ toolkit.
2  * Copyright (C) Index Data
3  * See the file LICENSE for details.
4  */
9 #if HAVE_CONFIG_H
10 #include <config.h>
11 #endif
12 
13 #include <string.h>
14 #include <yaz/base64.h>
15 
16 void yaz_base64encode(const char *in, char *out)
17 {
18  static char encoding[] =
19  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
20  unsigned char buf[3];
21  long n;
22 
23  while (*in != 0)
24  {
25  const char *pad = 0;
26  buf[0] = in[0];
27  buf[1] = in[1];
28  if (in[1] == 0)
29  {
30  buf[2] = 0;
31  pad = "==";
32  }
33  else
34  {
35  buf[2] = in[2];
36  if (in[2] == 0)
37  pad = "=";
38  }
39 
40  /* Treat three eight-bit numbers as on 24-bit number */
41  n = (buf[0] << 16) + (buf[1] << 8) + buf[2];
42 
43  /* Write the six-bit chunks out as four encoded characters */
44  *out++ = encoding[(n >> 18) & 63];
45  *out++ = encoding[(n >> 12) & 63];
46  if (in[1] != 0)
47  *out++ = encoding[(n >> 6) & 63];
48  if (in[1] != 0 && in[2] != 0)
49  *out++ = encoding[n & 63];
50 
51  if (pad != 0) {
52  while (*pad != 0)
53  *out++ = *pad++;
54  break;
55  }
56  in += 3;
57  }
58  *out++ = 0;
59 }
60 
61 static int next_char(const char **in, size_t *len)
62 {
63  const char *map = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
64  "abcdefghijklmnopqrstuvwxyz0123456789+/";
65  const char *p;
66  while (*len > 0 && strchr("\r\n\t\f ", **in))
67  {
68  (*len)--;
69  (*in)++;
70  }
71  if (*len > 0 && **in == '=')
72  return -2;
73  if (*len > 0 && (p = strchr(map, **in)))
74  {
75  (*len)--;
76  (*in)++;
77  return p - map;
78  }
79  return -1;
80 }
81 
82 int yaz_base64decode(const char *in, char *out)
83 {
84  size_t len = strlen(in);
85 
86  while (len >= 4)
87  {
88  int i0, i1, i2, i3;
89 
90  i0 = next_char(&in, &len);
91  if (i0 < 0)
92  return -1;
93  i1 = next_char(&in, &len);
94  if (i1 < 0)
95  return -1;
96  *(out++) = i0 << 2 | i1 >> 4;
97  i2 = next_char(&in, &len);
98  if (i2 == -2)
99  break;
100  if (i2 == -1)
101  return -1;
102  *(out++) = i1 << 4 | i2 >> 2;
103  i3 = next_char(&in, &len);
104  if (i3 == -2)
105  break;
106  if (i3 == -1)
107  return -1;
108  *(out++) = i2 << 6 | i3;
109  }
110  *out = '\0';
111  return 0;
112 }
113 
114 /*
115  * Local variables:
116  * c-basic-offset: 4
117  * c-file-style: "Stroustrup"
118  * indent-tabs-mode: nil
119  * End:
120  * vim: shiftwidth=4 tabstop=8 expandtab
121  */
122 
int yaz_base64decode(const char *in, char *out)
decodes Base64 string
Definition: base64.c:82
static int next_char(const char **in, size_t *len)
Definition: base64.c:61
Header for Base64 utilities.
void yaz_base64encode(const char *in, char *out)
encodes Base64 string
Definition: base64.c:16