/* Functions to compute MD5 message digest of files or memory blocks.
   according to the definition of MD5 in RFC 1321 from April 1992.
   Copyright (C) 1995,1996,1997,1999,2000,2001,2005,2006
	Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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, 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.  */


/* API pruned by Morten Welinder, 2015  */



#include "md5.h"

#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <glib.h>
#include <gsf/gsf-utils.h>

#if USE_UNLOCKED_IO
# include "unlocked-io.h"
#endif

/* Initialize structure containing state of computation.
   (RFC 1321, 3.3: Step 3)  */
void
md5_init_ctx (struct md5_ctx *ctx)
{
  ctx->A = 0x67452301;
  ctx->B = 0xefcdab89;
  ctx->C = 0x98badcfe;
  ctx->D = 0x10325476;

  ctx->total[0] = ctx->total[1] = 0;
  ctx->buflen = 0;
}

/* Put result from CTX in first 16 bytes following RESBUF.  The result
   will be in little endian byte order. */
void *
md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
{
	GSF_LE_SET_GUINT32 ((char *)resbuf + 0x00, ctx->A);
	GSF_LE_SET_GUINT32 ((char *)resbuf + 0x04, ctx->B);
	GSF_LE_SET_GUINT32 ((char *)resbuf + 0x08, ctx->C);
	GSF_LE_SET_GUINT32 ((char *)resbuf + 0x0c, ctx->D);
	return resbuf;
}

/* These are the four functions used in the four steps of the MD5 algorithm
   and defined in the RFC 1321.  The first function is a little bit optimized
   (as found in Colin Plumbs public domain implementation).  */
/* #define FF(b, c, d) ((b & c) | (~b & d)) */
#define FF(b, c, d) (d ^ (b & (c ^ d)))
#define FG(b, c, d) FF (d, b, c)
#define FH(b, c, d) (b ^ c ^ d)
#define FI(b, c, d) (c ^ (b | ~d))

/* Process LEN bytes of BUFFER, accumulating context into CTX.
   It is assumed that LEN % 64 == 0.  */

void
md5_process_block (const void *buffer, size_t len, struct md5_ctx *ctx)
{
  uint32_t correct_words[16];
  const uint32_t *words = buffer;
  size_t nwords = len / sizeof (uint32_t);
  const uint32_t *endp = words + nwords;
  uint32_t A = ctx->A;
  uint32_t B = ctx->B;
  uint32_t C = ctx->C;
  uint32_t D = ctx->D;

  /* First increment the byte count.  RFC 1321 specifies the possible
     length of the file up to 2^64 bits.  Here we only compute the
     number of bytes.  Do a double word increment.  */
  ctx->total[0] += len;
  if (ctx->total[0] < len)
    ++ctx->total[1];

  /* Process all bytes in the buffer with 64 bytes in each round of
     the loop.  */
  while (words < endp)
    {
      uint32_t *cwp = correct_words;
      uint32_t A_save = A;
      uint32_t B_save = B;
      uint32_t C_save = C;
      uint32_t D_save = D;

      /* First round: using the given function, the context and a constant
         the next context is computed.  Because the algorithms processing
         unit is a 32-bit word and it is determined to work on words in
         little endian byte order we perhaps have to change the byte order
         before the computation.  To reduce the work for the next steps
         we store the swapped words in the array CORRECT_WORDS.  */

#define OP(a, b, c, d, s, T)						\
      do								\
        {								\
	  a += FF (b, c, d) + (*cwp++ = GSF_LE_GET_GUINT32 (words)) + T;		\
	  ++words;							\
	  CYCLIC (a, s);						\
	  a += b;							\
        }								\
      while (0)

      /* It is unfortunate that C does not provide an operator for
         cyclic rotation.  Hope the C compiler is smart enough.  */
#define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))

      /* Before we start, one word to the strange constants.
         They are defined in RFC 1321 as

         T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64

         Here is an equivalent invocation using Perl:

         perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
       */

      /* Round 1.  */
      OP (A, B, C, D, 7, 0xd76aa478);
      OP (D, A, B, C, 12, 0xe8c7b756);
      OP (C, D, A, B, 17, 0x242070db);
      OP (B, C, D, A, 22, 0xc1bdceee);
      OP (A, B, C, D, 7, 0xf57c0faf);
      OP (D, A, B, C, 12, 0x4787c62a);
      OP (C, D, A, B, 17, 0xa8304613);
      OP (B, C, D, A, 22, 0xfd469501);
      OP (A, B, C, D, 7, 0x698098d8);
      OP (D, A, B, C, 12, 0x8b44f7af);
      OP (C, D, A, B, 17, 0xffff5bb1);
      OP (B, C, D, A, 22, 0x895cd7be);
      OP (A, B, C, D, 7, 0x6b901122);
      OP (D, A, B, C, 12, 0xfd987193);
      OP (C, D, A, B, 17, 0xa679438e);
      OP (B, C, D, A, 22, 0x49b40821);

      /* For the second to fourth round we have the possibly swapped words
         in CORRECT_WORDS.  Redefine the macro to take an additional first
         argument specifying the function to use.  */
#undef OP
#define OP(f, a, b, c, d, k, s, T)					\
      do								\
	{								\
	  a += f (b, c, d) + correct_words[k] + T;			\
	  CYCLIC (a, s);						\
	  a += b;							\
	}								\
      while (0)

      /* Round 2.  */
      OP (FG, A, B, C, D, 1, 5, 0xf61e2562);
      OP (FG, D, A, B, C, 6, 9, 0xc040b340);
      OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
      OP (FG, B, C, D, A, 0, 20, 0xe9b6c7aa);
      OP (FG, A, B, C, D, 5, 5, 0xd62f105d);
      OP (FG, D, A, B, C, 10, 9, 0x02441453);
      OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
      OP (FG, B, C, D, A, 4, 20, 0xe7d3fbc8);
      OP (FG, A, B, C, D, 9, 5, 0x21e1cde6);
      OP (FG, D, A, B, C, 14, 9, 0xc33707d6);
      OP (FG, C, D, A, B, 3, 14, 0xf4d50d87);
      OP (FG, B, C, D, A, 8, 20, 0x455a14ed);
      OP (FG, A, B, C, D, 13, 5, 0xa9e3e905);
      OP (FG, D, A, B, C, 2, 9, 0xfcefa3f8);
      OP (FG, C, D, A, B, 7, 14, 0x676f02d9);
      OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);

      /* Round 3.  */
      OP (FH, A, B, C, D, 5, 4, 0xfffa3942);
      OP (FH, D, A, B, C, 8, 11, 0x8771f681);
      OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
      OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
      OP (FH, A, B, C, D, 1, 4, 0xa4beea44);
      OP (FH, D, A, B, C, 4, 11, 0x4bdecfa9);
      OP (FH, C, D, A, B, 7, 16, 0xf6bb4b60);
      OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
      OP (FH, A, B, C, D, 13, 4, 0x289b7ec6);
      OP (FH, D, A, B, C, 0, 11, 0xeaa127fa);
      OP (FH, C, D, A, B, 3, 16, 0xd4ef3085);
      OP (FH, B, C, D, A, 6, 23, 0x04881d05);
      OP (FH, A, B, C, D, 9, 4, 0xd9d4d039);
      OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
      OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
      OP (FH, B, C, D, A, 2, 23, 0xc4ac5665);

      /* Round 4.  */
      OP (FI, A, B, C, D, 0, 6, 0xf4292244);
      OP (FI, D, A, B, C, 7, 10, 0x432aff97);
      OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
      OP (FI, B, C, D, A, 5, 21, 0xfc93a039);
      OP (FI, A, B, C, D, 12, 6, 0x655b59c3);
      OP (FI, D, A, B, C, 3, 10, 0x8f0ccc92);
      OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
      OP (FI, B, C, D, A, 1, 21, 0x85845dd1);
      OP (FI, A, B, C, D, 8, 6, 0x6fa87e4f);
      OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
      OP (FI, C, D, A, B, 6, 15, 0xa3014314);
      OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
      OP (FI, A, B, C, D, 4, 6, 0xf7537e82);
      OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
      OP (FI, C, D, A, B, 2, 15, 0x2ad7d2bb);
      OP (FI, B, C, D, A, 9, 21, 0xeb86d391);

      /* Add the starting values of the context.  */
      A += A_save;
      B += B_save;
      C += C_save;
      D += D_save;
    }

  /* Put checksum in context given as argument.  */
  ctx->A = A;
  ctx->B = B;
  ctx->C = C;
  ctx->D = D;
}
