/*= -*- c-basic-offset: 4; indent-tabs-mode: nil; -*-
 *
 * librsync -- the library for network deltas
 * $Id$
 * 
 * Copyright (C) 2000, 2001 by Martin Pool <mbp@sourcefrog.net>
 * Copyright (C) 1997-1999 by Andrew Tridgell
 * Copyright (C) 2002, 2003 by Donovan Baarda <abo@minkirri.apana.org.au> 
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/* MD4 message digest algorithm.
 *
 * TODO: Perhaps use the MD4 routine from OpenSSL if it's installed.
 * It's probably not worth the trouble.
 *
 * This was originally written by Andrew Tridgell for use in Samba. 
 * It was then modified by;
 * 
 * 2002-06-xx: Robert Weber <robert.weber@Colorado.edu> 
 *   optimisations and fixed >512M support.
 * 
 * 2002-06-27: Donovan Baarda <abo@minkirri.apana.org.au>
 *   further optimisations and cleanups.
 *
 * 2004-09-09: Simon Law  <sfllaw@debian.org>
 *   handle little-endian machines that can't do unaligned access
 *   (e.g. ia64, pa-risc).
 */

#include <config.h>

#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include "librsync.h"
#include "trace.h"
#include "types.h"
#include "mdfour.h"


#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)

/** padding data used for finalising */
static unsigned char PADDING[64] = {
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};


static void
rs_mdfour_block(rs_mdfour_t *md, void const *p);



/**
 * Update an MD4 accumulator from a 64-byte chunk.
 *
 * This cannot be used for the last chunk of the file, which must be
 * padded and contain the file length.  rs_mdfour_tail() is used for
 * that.
 *
 * \todo Recode to be fast, and to use system integer types.  Perhaps
 * if we can find an mdfour implementation already on the system
 * (e.g. in OpenSSL) then we should use it instead of our own?
 *
 * \param X A series of integer, read little-endian from the file.
 */
static void
rs_mdfour64(rs_mdfour_t * m, const void *p)
{
    uint32_t        AA, BB, CC, DD;
    uint32_t        A, B, C, D;
    const uint32_t *X = (const uint32_t *) p;

    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;

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


/**
 * These next routines are necessary because MD4 is specified in terms of
 * little-endian int32s, but we have a byte buffer.  On little-endian
 * platforms, I think we can just use the buffer pointer directly.
 * 
 * There are some nice endianness routines in glib, including assembler
 * variants. If we ever depended on glib, then it could be good to use them
 * instead. */
inline static void
copy4( /* @out@ */ unsigned char *out, uint32_t const x)
{
    out[0] = x;
    out[1] = x >> 8;
    out[2] = x >> 16;
    out[3] = x >> 24;
}


/* We need this if there is a uint64 */
/* --robert.weber@Colorado.edu	     */
#ifdef HAVE_UINT64
inline static void
copy8( /* @out@ */ unsigned char *out, uint64_t const x)
{
    out[0] = x;
    out[1] = x >> 8;
    out[2] = x >> 16;
    out[3] = x >> 24;
    out[4] = x >> 32;
    out[5] = x >> 40;
    out[6] = x >> 48;
    out[7] = x >> 56;
}
#endif /* HAVE_UINT64 */


/* We only need this if we are big-endian */
#ifdef WORDS_BIGENDIAN
inline static void
copy64( /* @out@ */ uint32_t * M, unsigned char const *in)
{
    int i=16;

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


/**
 * Accumulate a block, making appropriate conversions for bigendian
 * machines.
 */
inline static void
rs_mdfour_block(rs_mdfour_t *md, void const *p)
{
    uint32_t        M[16];

    copy64(M, p);
    rs_mdfour64(md, M);
}


#else /* WORDS_BIGENDIAN */

#  ifdef __i386__

/* If we are on an IA-32 machine, we can process directly. */
inline static void
rs_mdfour_block(rs_mdfour_t *md, void const *p)
{
    rs_mdfour64(md,p);
}

#  else /* !WORDS_BIGENDIAN && !__i386__ */

/* We are little-endian, but not on i386 and therefore may not be able
 * to do unaligned access safely/quickly.
 *
 * So if the input is not already aligned correctly, copy it to an
 * aligned buffer first.  */
inline static void
rs_mdfour_block(rs_mdfour_t *md, void const *p)
{
    unsigned long ptrval = (unsigned long) p;

    if (ptrval & 3) {
        uint32_t        M[16];
        
        memcpy(M, p, 16 * sizeof(uint32_t));
        rs_mdfour64(md, M);
    } else {
        rs_mdfour64(md, (const uint32_t *) p);
    }
}

#  endif /* ! __i386__ */
#endif /* WORDS_BIGENDIAN */


void
rs_mdfour_begin(rs_mdfour_t * md)
{
    memset(md, 0, sizeof(*md));
    md->A = 0x67452301;
    md->B = 0xefcdab89;
    md->C = 0x98badcfe;
    md->D = 0x10325476;
#if HAVE_UINT64
    md->totalN = 0;
#else 
    md->totalN_hi = md->totalN_lo = 0;
#endif
}


/**
 * Handle special behaviour for processing the last block of a file
 * when calculating its MD4 checksum.
 *
 * This must be called exactly once per file.
 *
 * Modified by Robert Weber to use uint64 in order that we can sum files
 * > 2^29 = 512 MB.  
 * --Robert.Weber@colorado.edu
 */
static void
rs_mdfour_tail(rs_mdfour_t * m)
{
#ifdef HAVE_UINT64
    uint64_t         b;
#else /* HAVE_UINT64 */
    uint32_t         b[2];
#endif /* HAVE_UINT64 */
    unsigned char   buf[8];
    size_t          pad_len;

    /* convert the totalN byte count into a bit count buffer */
#ifdef HAVE_UINT64
    b = m->totalN << 3;
    copy8(buf, b);
#else /* HAVE_UINT64 */
    b[0] = m->totalN_lo << 3;
    b[1] = ((m->totalN_hi << 3) | (m->totalN_lo >> 29));
    copy4(buf, b[0]);
    copy4(buf + 4, b[1]);
#endif /* HAVE_UINT64 */

    /* calculate length and process the padding data */
    pad_len=(m->tail_len <56) ? (56 - m->tail_len) : (120 - m->tail_len);
    rs_mdfour_update(m,PADDING,pad_len);
    /* process the bit count */
    rs_mdfour_update(m,buf,8);
}


/**
 * Feed some data into the MD4 accumulator.
 *
 * \param n Number of bytes fed in.
 */
void
rs_mdfour_update(rs_mdfour_t * md, void const *in_void, size_t n)
{
    unsigned char const        *in = (unsigned char const *) in_void;

    /* increment totalN */
#ifdef HAVE_UINT64
    md->totalN+=n;
#else /* HAVE_UINT64 */
    if ((md->totalN_lo += n) < n) 
	md->totalN_hi++;
#endif /* HAVE_UINT64 */

    /* If there's any leftover data in the tail buffer, then first we have
     * to make it up to a whole block to process it.  */
    if (md->tail_len) {
        size_t  tail_gap = 64 - md->tail_len;
        if (tail_gap <= n) {
            memcpy(&md->tail[md->tail_len], in, tail_gap);
            rs_mdfour_block(md, md->tail);
            in += tail_gap;
            n -= tail_gap;
            md->tail_len = 0;
        }
    }
    /* process complete blocks of input */
    while (n >= 64) {
        rs_mdfour_block(md, in);
        in += 64;
        n -= 64;
    }
    /* Put remaining bytes onto tail*/
    if (n) {
        memcpy(&md->tail[md->tail_len], in, n);
        md->tail_len += n;
    }
}


void
rs_mdfour_result(rs_mdfour_t * md, unsigned char *out)
{
    rs_mdfour_tail(md);

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


void
rs_mdfour(unsigned char *out, void const *in, size_t n)
{
    rs_mdfour_t     md;

    rs_mdfour_begin(&md);
    rs_mdfour_update(&md, in, n);
    rs_mdfour_result(&md, out);
}
