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/*
* base64.c -- base-64 conversion routines.
*
* For license terms, see the file COPYING in this directory.
*
* This base 64 encoding is defined in RFC2045 section 6.8,
* "Base64 Content-Transfer-Encoding", but lines must not be broken in the
* scheme used here.
*/
#include "config.h"
#include "fetchmail.h"
#include <ctype.h>
static const char base64digits[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
#define BAD -1
static const char base64val[] = {
BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD,
BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD,
BAD,BAD,BAD,BAD, BAD,BAD,BAD,BAD, BAD,BAD,BAD, 62, BAD,BAD,BAD, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61,BAD,BAD, BAD,BAD,BAD,BAD,
BAD, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,BAD, BAD,BAD,BAD,BAD,
BAD, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,BAD, BAD,BAD,BAD,BAD
};
#define DECODE64(c) (isascii((unsigned char)(c)) ? base64val[c] : BAD)
unsigned len64frombits(unsigned inlen)
{
return (inlen + 2)/3*4;
}
int to64frombits(char *out, const void *in_, int inlen, size_t outlen)
/* raw bytes in quasi-big-endian order to base 64 string (NUL-terminated) */
{
int rc = 0;
const unsigned char *in = (const unsigned char *)in_;
for (; inlen >= 3; inlen -= 3)
{
if (outlen < 5) { rc = -1; goto fail; } /* buffer too small */
*out++ = base64digits[in[0] >> 2];
*out++ = base64digits[((in[0] << 4) & 0x30) | (in[1] >> 4)];
*out++ = base64digits[((in[1] << 2) & 0x3c) | (in[2] >> 6)];
*out++ = base64digits[in[2] & 0x3f];
in += 3;
outlen -= 4;
}
if (inlen > 0)
{
unsigned char fragment;
if (outlen < 5) { rc = -1; goto fail; } /* buffer too small */
*out++ = base64digits[in[0] >> 2];
fragment = (in[0] << 4) & 0x30;
if (inlen > 1)
fragment |= in[1] >> 4;
*out++ = base64digits[fragment];
*out++ = (inlen < 2) ? '=' : base64digits[(in[1] << 2) & 0x3c];
*out++ = '=';
}
fail:
*out = '\0';
return rc;
}
int from64tobits(void *out_, const char *in, int maxlen)
/* base 64 to raw bytes in quasi-big-endian order, returning count of bytes */
/* maxlen limits output buffer size, set to zero to ignore */
{
int len = 0;
unsigned char digit1, digit2, digit3, digit4;
unsigned char *out = (unsigned char *)out_;
if (in[0] == '+' && in[1] == ' ')
in += 2;
if (*in == '\r')
return(0);
do {
digit1 = in[0];
if (DECODE64(digit1) == BAD)
return(-1);
digit2 = in[1];
if (DECODE64(digit2) == BAD)
return(-1);
digit3 = in[2];
if (digit3 != '=' && DECODE64(digit3) == BAD)
return(-1);
digit4 = in[3];
if (digit4 != '=' && DECODE64(digit4) == BAD)
return(-1);
in += 4;
++len;
if (maxlen && len > maxlen)
return(-1);
*out++ = (DECODE64(digit1) << 2) | (DECODE64(digit2) >> 4);
if (digit3 != '=')
{
++len;
if (maxlen && len > maxlen)
return(-1);
*out++ = ((DECODE64(digit2) << 4) & 0xf0) | (DECODE64(digit3) >> 2);
if (digit4 != '=')
{
++len;
if (maxlen && len > maxlen)
return(-1);
*out++ = ((DECODE64(digit3) << 6) & 0xc0) | DECODE64(digit4);
}
}
} while
(*in && *in != '\r' && digit4 != '=');
return len;
}
/* base64.c ends here */
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