/* base64.c, Copyright 2000 (C) Oliver Kurth,
 *
 * This program 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
 * (at your option) any later version.
 * 
 * This program 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 program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 send bugs to: kurth@innominate.de
*/

/* see also RFC 1341 */

#include <glib.h>
#include <string.h>
#include "base64.h"

gchar *base64_encode(guchar *buf, gint len)
{
  guchar *outbuf, *q;
  gchar enc[64];
  gint i = 0, j = 0;
  guint in0, in1, in2;

  for(; i < 26; i++) enc[i] = (gchar)('A' + j++); j = 0;
  for(; i < 52; i++) enc[i] = (gchar)('a' + j++); j = 0;
  for(; i < 62; i++) enc[i] = (gchar)('0' + j++);
  enc[i++] = '+';
  enc[i++] = '/';

  outbuf = g_malloc(((len+3) * 8)/6);
  q = outbuf;

  i = 0;
  while(i < len-2){
    in0 = buf[i++];
    in1 = buf[i++];
    in2 = buf[i++];

    *(q++) = enc[(in0 >> 2) & 0x3f];
    *(q++) = enc[((in0 << 4) | (in1 >> 4)) & 0x3f];
    *(q++) = enc[((in1 << 2) | (in2 >> 6)) & 0x3f];
    *(q++) = enc[in2 & 0x3f];
  }
  if((len - i) == 1){
    in0 = buf[i++];
    *(q++) = enc[(in0 >> 2) & 0x3f];
    *(q++) = enc[(in0 << 4) & 0x3f];
    *(q++) = '=';
    *(q++) = '=';
  }else if((len - i) == 2){
    in0 = buf[i++];
    in1 = buf[i++];
    *(q++) = enc[(in0 >> 2) & 0x3f];
    *(q++) = enc[((in0 << 4) | (in1 >> 4)) & 0x3f];
    *(q++) = enc[(in1 << 2) & 0x3f];
    *(q++) = '=';
  }
  *q = 0;
  
  return outbuf;
}
    
gchar *base64_decode(gchar *buf, gint *size)
{
  guchar *p = buf, *q;
  guint in[4];
  //  gchar *out = g_malloc(((strlen(buf)+3) * 3) / 4 + 1);
  gchar *out = g_malloc((strlen(buf)+3) + 1);

  q = out;
  *size = 0;

  *q = 0;

  while(*p){
    int i = 0;
    while(i < 4){
      if(!*p) break;
      if((*p >= 'A') && (*p <= 'Z'))
	 in[i++] = *p - 'A';
      else if((*p >= 'a') && (*p <= 'z'))
	in[i++] = (*p - 'a') + 26;
      else if((*p >= '0') && (*p <= '9'))
	in[i++] = (*p - '0') + 52;
      else if(*p == '+')
	in[i++] = 62;
      else if(*p == '/')
	in[i++] = 63;
      else if(*p == '='){
	in[i++] = 0;
	p++;
	break;
      }else if((*p != '\r') && (*p != '\n')){
	p++;
	break;
      }
      p++;
    }
    if((i == 4) || (p[-1] == '=')){
      *(q++) = ((in[0] << 2) | (in[1] >> 4));
      *(q++) = ((in[1] << 4) | (in[2] >> 2));
      *(q++) = ((in[2] << 6) | in[3]);
      if(p[-1] == '='){
	if(i == 3){
	  (*size)++;
	}
	else if(i == 4){
	  (*size) += 2;
	}
      }else{
	*size += 3;
      }
    }
  }
  return out;
}