/*
 *     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., 59 Temple Place - Suite 330, 
 *     Boston, MA  02111, USA.
 * 
 */

/* 
 * Base64 handling elsewhere in mutt should be modified to call
 * these routines. These routines were written because IMAP's
 * AUTHENTICATE protocol required them, and base64 handling
 * elsewhere wasn't sufficiently generic.
 * 
 */

/* 
 * This code is heavily modified from fetchmail (also GPL'd, of
 * course) by Brendan Cully <brendan@kublai.com>.
 * 
 * Original copyright notice:
 * 
 * The code in the fetchmail distribution is Copyright 1997 by Eric
 * S. Raymond.  Portions are also copyrighted by Carl Harris, 1993
 * and 1995.  Copyright retained for the purpose of protecting free
 * redistribution of source. 
 * 
 */

/* This file was taken from Mutt, and modified where needed.
 * Mutt is Copyright Notice follows:
 *
 * The following copyright notices apply to most of the program.  Some
 * modules are under different licenses, or in the public domain.
 *
 * Please note that this is by no means an exhaustive list of all the
 * persons who have been contributing to this program.  Please see the
 * manual for a (probably still non complete) list of the persons who
 * have been helpful with the development of this program.
 *
 * Copyright (C) 1996-2001 Michael R. Elkins <me@cs.hmc.edu>
 * Copyright (C) 1996-2001 Brandon Long <blong@fiction.net>
 * Copyright (C) 1997-2001 Thomas Roessler <roessler@guug.de>
 * Copyright (C) 1998-2001 Werner Koch <wk@isil.d.shuttle.de>
 * Copyright (C) 1999-2001 Brendan Cully <brendan@kublai.com>
 * Copyright (C) 1999-2001 Tommi Komulainen <Tommi.Komulainen@iki.fi>
 * Copyright (C) 2000-2001 Edmund Grimley Evans <edmundo@rano.org>
 *
 */

#include <sys/types.h>
#include "mime.h"

#define BAD     -1

char B64Chars[64] = {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
  'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
  'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
  't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
  '8', '9', '+', '/'
};

int Index_64[128] = {
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
    52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1,
    -1, 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,-1, -1,-1,-1,-1,
    -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
    41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
};

/* raw bytes to null-terminated base 64 string */
void raw_to_base64 (unsigned char *out, const unsigned char *in, size_t len,
		     size_t olen)
{
  int linelen = 0;
  while (len >= 3 && olen > 10)
  {
    if ( linelen >= 72 ) {
	    *out++ = '\n';
	    olen--;
	    linelen=0;
    }
    *out++ = B64Chars[in[0] >> 2];
    *out++ = B64Chars[((in[0] << 4) & 0x30) | (in[1] >> 4)];
    *out++ = B64Chars[((in[1] << 2) & 0x3c) | (in[2] >> 6)];
    *out++ = B64Chars[in[2] & 0x3f];
    olen  -= 4;
    len   -= 3;
    in    += 3;
    linelen += 4;
  }

  /* clean up remainder */
  if (len > 0 && olen > 4)
  {
    unsigned char fragment;

    *out++ = B64Chars[in[0] >> 2];
    fragment = (in[0] << 4) & 0x30;
    if (len > 1)
      fragment |= in[1] >> 4;
    *out++ = B64Chars[fragment];
    *out++ = (len < 2) ? '=' : B64Chars[(in[1] << 2) & 0x3c];
    *out++ = '=';
  }
  *out = '\0';
}

/* Convert '\0'-terminated base 64 string to raw bytes.
 * Returns length of returned buffer, or -1 on error */
int raw_from_base64 (char *out, const char *in)
{
  int len = 0;
  register unsigned char digit1, digit2, digit3, digit4;

  do
  {
    digit1 = in[0];
    if (digit1 > 127 || base64val (digit1) == BAD)
      return -1;
    digit2 = in[1];
    if (digit2 > 127 || base64val (digit2) == BAD)
      return -1;
    digit3 = in[2];
    if (digit3 > 127 || ((digit3 != '=') && (base64val (digit3) == BAD)))
      return -1;
    digit4 = in[3];
    if (digit4 > 127 || ((digit4 != '=') && (base64val (digit4) == BAD)))
      return -1;
    in += 4;

    /* digits are already sanity-checked */
    *out++ = (base64val(digit1) << 2) | (base64val(digit2) >> 4);
    len++;
    if (digit3 != '=')
    {
      *out++ = ((base64val(digit2) << 4) & 0xf0) | (base64val(digit3) >> 2);
      len++;
      if (digit4 != '=')
      {
	*out++ = ((base64val(digit3) << 6) & 0xc0) | base64val(digit4);
	len++;
      }
    }
  }
  while (*in && digit4 != '=');

  return len;
}