path: root/src/base64.cpp

/*
 *  This file is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  any later version.
 *
 *  This file is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this file; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  $Id$
 */

#include "base64.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(c) ? base64val[c] : BAD)

void to64frombits(unsigned char *out, const unsigned char *in, int inlen)
{
    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 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;
        *out++ = (DECODE64(digit1) << 2) | (DECODE64(digit2) >> 4);
        ++len;
        if (digit3 != '=')
        {
            *out++ = ((DECODE64(digit2) << 4) & 0xf0) | (DECODE64(digit3) >> 2);
            ++len;
            if (digit4 != '=')
            {
                *out++ = ((DECODE64(digit3) << 6) & 0xc0) | DECODE64(digit4);
                ++len;
            }
        }
    } while (*in && *in != '\r' && digit4 != '=');

    return (len);
}