/*
	$RCSfile: mdfour.c,v $

	Copyright (C) 1997-1998  Andrew Tridgell
	Copyright (C) 2000       Jeff Teunissen <d2deek@pmail.net>

	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:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <string.h>

/* NOTE: This code makes no attempt to be fast!

   It assumes that a int is at least 32 bits long
*/

struct mdfour {
	unsigned A, B, C, D;
	unsigned totalN;
};

static struct mdfour *m;

#define F(X,Y,Z) (((X)&(Y)) | ((~(X))&(Z)))
#define G(X,Y,Z) (((X)&(Y)) | ((X)&(Z)) | ((Y)&(Z)))
#define H(X,Y,Z) ((X)^(Y)^(Z))
#define lshift(x,s) (((x)<<(s)) | ((x)>>(32-(s))))

#define ROUND1(a,b,c,d,k,s) a = lshift(a + F(b,c,d) + X[k], s)
#define ROUND2(a,b,c,d,k,s) a = lshift(a + G(b,c,d) + X[k] + 0x5A827999,s)
#define ROUND3(a,b,c,d,k,s) a = lshift(a + H(b,c,d) + X[k] + 0x6ED9EBA1,s)

/* this applies md4 to 64 byte chunks */
static void mdfour64 (unsigned *M)
{
	int         j;
	unsigned	AA, BB, CC, DD;
	unsigned	X[16];
	unsigned	A, B, C, D;

	for (j = 0; j < 16; j++)
		X[j] = M[j];

	A = m->A;
	B = m->B;
	C = m->C;
	D = m->D;
	AA = A;
	BB = B;
	CC = C;
	DD = D;

	ROUND1 (A, B, C, D, 0, 3);
	ROUND1 (D, A, B, C, 1, 7);
	ROUND1 (C, D, A, B, 2, 11);
	ROUND1 (B, C, D, A, 3, 19);
	ROUND1 (A, B, C, D, 4, 3);
	ROUND1 (D, A, B, C, 5, 7);
	ROUND1 (C, D, A, B, 6, 11);
	ROUND1 (B, C, D, A, 7, 19);
	ROUND1 (A, B, C, D, 8, 3);
	ROUND1 (D, A, B, C, 9, 7);
	ROUND1 (C, D, A, B, 10, 11);
	ROUND1 (B, C, D, A, 11, 19);
	ROUND1 (A, B, C, D, 12, 3);
	ROUND1 (D, A, B, C, 13, 7);
	ROUND1 (C, D, A, B, 14, 11);
	ROUND1 (B, C, D, A, 15, 19);

	ROUND2 (A, B, C, D, 0, 3);
	ROUND2 (D, A, B, C, 4, 5);
	ROUND2 (C, D, A, B, 8, 9);
	ROUND2 (B, C, D, A, 12, 13);
	ROUND2 (A, B, C, D, 1, 3);
	ROUND2 (D, A, B, C, 5, 5);
	ROUND2 (C, D, A, B, 9, 9);
	ROUND2 (B, C, D, A, 13, 13);
	ROUND2 (A, B, C, D, 2, 3);
	ROUND2 (D, A, B, C, 6, 5);
	ROUND2 (C, D, A, B, 10, 9);
	ROUND2 (B, C, D, A, 14, 13);
	ROUND2 (A, B, C, D, 3, 3);
	ROUND2 (D, A, B, C, 7, 5);
	ROUND2 (C, D, A, B, 11, 9);
	ROUND2 (B, C, D, A, 15, 13);

	ROUND3 (A, B, C, D, 0, 3);
	ROUND3 (D, A, B, C, 8, 9);
	ROUND3 (C, D, A, B, 4, 11);
	ROUND3 (B, C, D, A, 12, 15);
	ROUND3 (A, B, C, D, 2, 3);
	ROUND3 (D, A, B, C, 10, 9);
	ROUND3 (C, D, A, B, 6, 11);
	ROUND3 (B, C, D, A, 14, 15);
	ROUND3 (A, B, C, D, 1, 3);
	ROUND3 (D, A, B, C, 9, 9);
	ROUND3 (C, D, A, B, 5, 11);
	ROUND3 (B, C, D, A, 13, 15);
	ROUND3 (A, B, C, D, 3, 3);
	ROUND3 (D, A, B, C, 11, 9);
	ROUND3 (C, D, A, B, 7, 11);
	ROUND3 (B, C, D, A, 15, 15);

	A += AA;
	B += BB;
	C += CC;
	D += DD;

	for (j = 0; j < 16; j++)
		X[j] = 0;

	m->A = A;
	m->B = B;
	m->C = C;
	m->D = D;
}

static void copy64 (unsigned *M, unsigned char *in)
{
	int         i;

	for (i = 0; i < 16; i++)
		M[i] = (in[i * 4 + 3] << 24) | (in[i * 4 + 2] << 16) |
			(in[i * 4 + 1] << 8) | (in[i * 4 + 0] << 0);
}

static void copy4 (unsigned char *out, unsigned x)
{
	out[0] = (unsigned char)(x & 0xFF);
	out[1] = (unsigned char)((x >> 8) & 0xFF);
	out[2] = (unsigned char)((x >> 16) & 0xFF);
	out[3] = (unsigned char)((x >> 24) & 0xFF);
}

void mdfour_begin (struct mdfour *md)
{
	md->A = 0x67452301;
	md->B = 0xefcdab89;
	md->C = 0x98badcfe;
	md->D = 0x10325476;
	md->totalN = 0;
}

static void mdfour_tail (unsigned char *in, int n)
{
	unsigned char buf[128];
	unsigned M[16];
	unsigned b;

	m->totalN += n;

	b = m->totalN * 8;

	memset (buf, 0, 128);
	if (n)
		memcpy (buf, in, n);
	buf[n] = 0x80;

	if (n <= 55) {
		copy4 (buf + 56, b);
		copy64 (M, buf);
		mdfour64 (M);
	} else {
		copy4 (buf + 120, b);
		copy64 (M, buf);
		mdfour64 (M);
		copy64 (M, buf + 64);
		mdfour64 (M);
	}
}

void mdfour_update (struct mdfour *md, unsigned char *in, int n)
{
	unsigned M[16];

	if (n == 0)
		mdfour_tail (in, n);

	m = md;

	while (n >= 64) {
		copy64 (M, in);
		mdfour64 (M);
		in += 64;
		n -= 64;
		m->totalN += 64;
	}

	mdfour_tail (in, n);
}


void mdfour_result (struct mdfour *md, unsigned char *out)
{
	m = md;

	copy4 (out, m->A);
	copy4 (out + 4, m->B);
	copy4 (out + 8, m->C);
	copy4 (out + 12, m->D);
}

void mdfour (unsigned char *out, unsigned char *in, int n)
{
	struct mdfour md;

	mdfour_begin (&md);
	mdfour_update (&md, in, n);
	mdfour_result (&md, out);
}

unsigned Com_BlockChecksum (void *buffer, int length)
{
	unsigned char digest[16];

	mdfour ((unsigned char *) digest, (unsigned char *) buffer, length);

	/*
	 * This is intentional.  digest can't be 4 unsigned integers because of
	 * possible alignment issues.
	 */
	return ((unsigned *)digest)[0] ^
				((unsigned *)digest)[1] ^
				((unsigned *)digest)[2] ^
				((unsigned *)digest)[3];
}

