/*
	An implementation of MD4 designed for use in the samba SMB
	authentication protocol

	Copyright (C) 1997-1998  Andrew Tridgell

	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
*/

// NOTE: This code makes no attempt to be fast!
// It assumes that a int is at least 32 bits long

#include "q_shared.h"
#include "qcommon.h"

struct md4ctx {
	uint32_t A, B, C, D;
	uint32_t totalN;
};

#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( md4ctx& md, const uint32_t* M )
{
	int j;
	uint32_t AA, BB, CC, DD;
	uint32_t X[16];
	uint32_t A,B,C,D;

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

	A = md.A; B = md.B; C = md.C; D = md.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;

	md.A = A; md.B = B; md.C = C; md.D = D;
}

static void copy64( uint32_t* M, const byte* 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( byte* out, uint32_t x )
{
	out[0] = x & 0xFF;
	out[1] = (x>>8) & 0xFF;
	out[2] = (x>>16) & 0xFF;
	out[3] = (x>>24) & 0xFF;
}

static void mdfour_begin( md4ctx& md )
{
	md.A = 0x67452301;
	md.B = 0xefcdab89;
	md.C = 0x98badcfe;
	md.D = 0x10325476;
	md.totalN = 0;
}

static void mdfour_tail( md4ctx& md, const byte* in, int n )
{
	byte buf[128];
	uint32_t M[16];
	uint32_t b;

	md.totalN += n;

	b = md.totalN * 8;

	Com_Memset(buf, 0, 128);
	if (n) Com_Memcpy(buf, in, n);
	buf[n] = 0x80;

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

static void mdfour_update( md4ctx& md, const byte* in, int n )
{
	uint32_t M[16];

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

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

	mdfour_tail(md, in, n);
}

static void mdfour_result( md4ctx& md, byte* out )
{
	copy4(out, md.A);
	copy4(out+4, md.B);
	copy4(out+8, md.C);
	copy4(out+12, md.D);
}

static void mdfour( byte* out, const byte* in, int n )
{
	md4ctx md;
	mdfour_begin(md);
	mdfour_update(md, in, n);
	mdfour_result(md, out);
}

///////////////////////////////////////////////////////////////

unsigned Com_BlockChecksum( const void* buffer, int length )
{
	int digest[4];
	mdfour( (byte*)digest, (const byte*)buffer, length );
	return (unsigned)( digest[0] ^ digest[1] ^ digest[2] ^ digest[3] );
}