/*
 * ImapProxy - a caching IMAP proxy daemon
 * Copyright (C) 2002 Steven Van Acker
 * 
 * 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.
 *
 */


/*
 * Ripped from http://www.episec.com/people/edelkind/arc/c/misc/base64.c
 * Written by ari edelkind <edelkind-w@iownanisp.com>
 *
 */

#include <string.h>

char b64string[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

int base64encode (char *to, char *from, unsigned int len)
{
	char *fromp = from;
	char *top = to;
	unsigned char cbyte;
	unsigned char obyte;
	char end[3];

	for (; len >= 3; len -= 3) 
	{
	    cbyte = *fromp++;
		*top++ = b64string[(int)(cbyte >> 2)];
		obyte = (cbyte << 4) & 0x30;		/* 0011 0000 */

		cbyte = *fromp++;
		obyte |= (cbyte >> 4);			/* 0000 1111 */
		*top++ = b64string[(int)obyte];
		obyte = (cbyte << 2) & 0x3C;		/* 0011 1100 */

		cbyte = *fromp++;
		obyte |= (cbyte >> 6);			/* 0000 0011 */
		*top++ = b64string[(int)obyte];
		*top++ = b64string[(int)(cbyte & 0x3F)];/* 0011 1111 */
	}

	if (len) {
		end[0] = *fromp++;
		if (--len) end[1] = *fromp++; else end[1] = 0;
		end[2] = 0;

		cbyte = end[0];
		*top++ = b64string[(int)(cbyte >> 2)];
		obyte = (cbyte << 4) & 0x30;		/* 0011 0000 */

		cbyte = end[1];
		obyte |= (cbyte >> 4);
		*top++ = b64string[(int)obyte];
		obyte = (cbyte << 2) & 0x3C;		/* 0011 1100 */

		if (len) *top++ = b64string[(int)obyte];
		else *top++ = '=';
		*top++ = '=';
	}
	*top = 0;
	return top - to;
}

/* badchar(): check if c is decent; puts either the */
/* location of c or null into p.                  */
#define badchar(c,p) (!(p = memchr(b64string, c, 64)))

int base64decode (char *to, char *from, unsigned int len)
{
	char *fromp = from;
	char *top = to;
	char *p;
	unsigned char cbyte;
	unsigned char obyte;
	int padding = 0;

	for (; len >= 4; len -= 4) {
		if ((cbyte = *fromp++) == '=') cbyte = 0;
		else {
			if (badchar(cbyte, p)) return -1;
			cbyte = (p - b64string);
		}
		obyte = cbyte << 2;		/* 1111 1100 */

		if ((cbyte = *fromp++) == '=') cbyte = 0;
		else {
			if (badchar(cbyte, p)) return -1;
			cbyte = p - b64string;
		}
		obyte |= cbyte >> 4;		/* 0000 0011 */
		*top++ = obyte;

		obyte = cbyte << 4;		/* 1111 0000 */
		if ((cbyte = *fromp++) == '=') { cbyte = 0; padding++; }
		else {
			padding = 0;
			if (badchar (cbyte, p)) return -1;
			cbyte = p - b64string;
		}
		obyte |= cbyte >> 2;		/* 0000 1111 */
		*top++ = obyte;

		obyte = cbyte << 6;		/* 1100 0000 */
		if ((cbyte = *fromp++) == '=') { cbyte = 0; padding++; }
		else {
			padding = 0;
			if (badchar (cbyte, p)) return -1;
			cbyte = p - b64string;
		}
		obyte |= cbyte;			/* 0011 1111 */
		*top++ = obyte;
	}

	*top = 0;
	if (len) return -1;
	return (top - to) - padding;
}