2 * base64.c -- base-64 conversion routines.
4 * For license terms, see the file COPYING in this directory.
6 * This base 64 encoding is defined in RFC2045 section 6.8,
7 * "Base64 Content-Transfer-Encoding", but lines must not be broken in the
11 #include "fetchmail.h"
14 static const char base64digits[] =
15 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
18 static const char base64val[] = {
19 BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD,
20 BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD,
21 BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD, 62, BAD,BAD,BAD, 63,
22 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,BAD,BAD, BAD,BAD,BAD,BAD,
23 BAD, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
24 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,BAD, BAD,BAD,BAD,BAD,
25 BAD, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
26 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,BAD, BAD,BAD,BAD,BAD
28 #define DECODE64(c) (isascii((unsigned char)(c)) ? base64val[c] : BAD)
30 void to64frombits(char *out, const void *in_, int inlen)
31 /* raw bytes in quasi-big-endian order to base 64 string (NUL-terminated) */
33 const unsigned char *in = (const unsigned char *)in_;
35 for (; inlen >= 3; inlen -= 3)
37 *out++ = base64digits[in[0] >> 2];
38 *out++ = base64digits[((in[0] << 4) & 0x30) | (in[1] >> 4)];
39 *out++ = base64digits[((in[1] << 2) & 0x3c) | (in[2] >> 6)];
40 *out++ = base64digits[in[2] & 0x3f];
45 unsigned char fragment;
47 *out++ = base64digits[in[0] >> 2];
48 fragment = (in[0] << 4) & 0x30;
50 fragment |= in[1] >> 4;
51 *out++ = base64digits[fragment];
52 *out++ = (inlen < 2) ? '=' : base64digits[(in[1] << 2) & 0x3c];
58 int from64tobits(void *out_, const char *in, int maxlen)
59 /* base 64 to raw bytes in quasi-big-endian order, returning count of bytes */
60 /* maxlen limits output buffer size, set to zero to ignore */
63 register unsigned char digit1, digit2, digit3, digit4;
64 unsigned char *out = (unsigned char *)out_;
66 if (in[0] == '+' && in[1] == ' ')
73 if (DECODE64(digit1) == BAD)
76 if (DECODE64(digit2) == BAD)
79 if (digit3 != '=' && DECODE64(digit3) == BAD)
82 if (digit4 != '=' && DECODE64(digit4) == BAD)
86 if (maxlen && len > maxlen)
88 *out++ = (DECODE64(digit1) << 2) | (DECODE64(digit2) >> 4);
92 if (maxlen && len > maxlen)
94 *out++ = ((DECODE64(digit2) << 4) & 0xf0) | (DECODE64(digit3) >> 2);
98 if (maxlen && len > maxlen)
100 *out++ = ((DECODE64(digit3) << 6) & 0xc0) | DECODE64(digit4);
104 (*in && *in != '\r' && digit4 != '=');
109 /* base64.c ends here */