/*
* 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 <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(c) ? base64val[c] : BAD)

void to64frombits(unsigned char *out, const unsigned char *in, int inlen)
/* raw bytes in quasi-big-endian order to base 64 string (NUL-terminated) */
{
   for (; inlen >= 3; inlen -= 3)
   {
       *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;
   }
   if (inlen > 0)
   {
       unsigned char fragment;

       *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++ = '=';
   }
   *out = '\0';
}

int from64tobits(char *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;
   register unsigned char digit1, digit2, digit3, digit4;

   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 */