proxytunnel/base64.c

/* Proxytunnel - (C) 2001-2002 Jos Visser / Mark Janssen    */
/* Contact:                  josv@osp.nl / maniac@maniac.nl */

/*
 * 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 02111-1307 USA
 */

#include <stdio.h>
#include "config.h"
#include "cmdline.h"
#include "base64.h"
#include <ctype.h>

/* Needed for base64 encoding... */
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)


/*
 * Small MAX macro
 */
#ifndef MAX
#define MAX( x, y )	( ( (x)>(y) ) ? (x) : (y) )
#endif

/* 
 * This base64 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. 
 * 
 */

/* raw bytes to null-terminated base 64 string */
void base64(unsigned char *out, const unsigned char *in, int len)
{
  while (len >= 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];
    len -= 3;
    in += 3;
 }

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

    *out++ = base64digits[in[0] >> 2];
    fragment = (in[0] << 4) & 0x30;
    if (len > 1)
      fragment |= in[1] >> 4;
    *out++ = base64digits[fragment];
    *out++ = (len < 2) ? '=' : base64digits[(in[1] << 2) & 0x3c];
    *out++ = '=';
  }
  *out = '\0';
}

int unbase64(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);
}