/*****************************************************************************
*
* "derived from the RSA Data Security, Inc. MD5 Message-Digest Algorithm".
*
* 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
*
*****************************************************************************/

#include <endian.h>
#include <md5.h>
#include <string.h>

#if (__BYTE_ORDER == __BIG_ENDIAN)
/*
   Block copy and convert byte order to little-endian.
   dst must be 32bit aligned.
   Length is the number of 32bit words 
*/   
static void CopyToLittleEndian (uint32_t *dst, const uint8_t *src, int length) {
  while (length--) {
    *dst=(((uint32_t)src[3])<<24) |
	 (((uint32_t)src[2])<<16) |
	 (((uint32_t)src[1])<< 8) |
	   (uint32_t)src[0];
    src+=4;
    dst++;
  }
}
#endif


/*
   Assembler versions of __MD5Transform, MD5Init and MD5Update
   currently exist for x86 and little-endian ARM.
   For other targets, we need to use the C versions below.
*/

#if !(defined (__i386__) || ((defined (__arm__) && (__BYTE_ORDER == __LITTLE_ENDIAN))))

/*
   Initialise the MD5 context.
*/
void MD5Init (MD5_CTX* context) {
   context->count[0] = 0;
   context->count[1] = 0;

   context->state[0] = 0x67452301;              /* Load magic constants. */
   context->state[1] = 0xefcdab89;
   context->state[2] = 0x98badcfe;
   context->state[3] = 0x10325476;
}

#define ROTATE_LEFT(x, n) ((x << n) | (x >> (32-n)))

#define F(x, y, z) (z ^ (x & (y ^ z)))
#define G(x, y, z) (y ^ (z & (x ^ y)))
#define H(x, y, z) (x ^ y ^ z)
#define I(x, y, z) (y ^ (x | ~z))

#define FF(a, b, c, d, x, s, ac) { (a) += F (b, c, d) + (x) + (uint32_t)(ac); (a) = ROTATE_LEFT (a, s); (a) += (b); }
#define GG(a, b, c, d, x, s, ac) { (a) += G (b, c, d) + (x) + (uint32_t)(ac); (a) = ROTATE_LEFT (a, s); (a) += (b); }
#define HH(a, b, c, d, x, s, ac) { (a) += H (b, c, d) + (x) + (uint32_t)(ac); (a) = ROTATE_LEFT (a, s); (a) += (b); }
#define II(a, b, c, d, x, s, ac) { (a) += I (b, c, d) + (x) + (uint32_t)(ac); (a) = ROTATE_LEFT (a, s); (a) += (b); }

static void __MD5Transform (uint32_t state[4], const uint8_t *in, int repeat) {
   const uint32_t *x;

   uint32_t  a = state[0];
   uint32_t  b = state[1];
   uint32_t  c = state[2];
   uint32_t  d = state[3];

   for ( ; repeat; repeat--) {
      uint32_t tempBuffer[16];
#if (__BYTE_ORDER == __BIG_ENDIAN)

      CopyToLittleEndian (tempBuffer, in, 16);
      x = tempBuffer;
#else
      if ((long)in & 3) {
	memcpy(tempBuffer, in, 64);
	x = tempBuffer;
      } else
	x = (const uint32_t *) in;
#endif

      FF (a, b, c, d, x[ 0],  7, 0xd76aa478); /*  1 */     /* Round 1 */
      FF (d, a, b, c, x[ 1], 12, 0xe8c7b756); /*  2 */
      FF (c, d, a, b, x[ 2], 17, 0x242070db); /*  3 */
      FF (b, c, d, a, x[ 3], 22, 0xc1bdceee); /*  4 */
      FF (a, b, c, d, x[ 4],  7, 0xf57c0faf); /*  5 */
      FF (d, a, b, c, x[ 5], 12, 0x4787c62a); /*  6 */
      FF (c, d, a, b, x[ 6], 17, 0xa8304613); /*  7 */
      FF (b, c, d, a, x[ 7], 22, 0xfd469501); /*  8 */
      FF (a, b, c, d, x[ 8],  7, 0x698098d8); /*  9 */
      FF (d, a, b, c, x[ 9], 12, 0x8b44f7af); /* 10 */
      FF (c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
      FF (b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
      FF (a, b, c, d, x[12],  7, 0x6b901122); /* 13 */
      FF (d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
      FF (c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
      FF (b, c, d, a, x[15], 22, 0x49b40821); /* 16 */

      GG (a, b, c, d, x[ 1],  5, 0xf61e2562); /* 17 */     /* Round 2 */
      GG (d, a, b, c, x[ 6],  9, 0xc040b340); /* 18 */
      GG (c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
      GG (b, c, d, a, x[ 0], 20, 0xe9b6c7aa); /* 20 */
      GG (a, b, c, d, x[ 5],  5, 0xd62f105d); /* 21 */
      GG (d, a, b, c, x[10],  9, 0x02441453); /* 22 */
      GG (c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
      GG (b, c, d, a, x[ 4], 20, 0xe7d3fbc8); /* 24 */
      GG (a, b, c, d, x[ 9],  5, 0x21e1cde6); /* 25 */
      GG (d, a, b, c, x[14],  9, 0xc33707d6); /* 26 */
      GG (c, d, a, b, x[ 3], 14, 0xf4d50d87); /* 27 */
      GG (b, c, d, a, x[ 8], 20, 0x455a14ed); /* 28 */
      GG (a, b, c, d, x[13],  5, 0xa9e3e905); /* 29 */
      GG (d, a, b, c, x[ 2],  9, 0xfcefa3f8); /* 30 */
      GG (c, d, a, b, x[ 7], 14, 0x676f02d9); /* 31 */
      GG (b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */

      HH (a, b, c, d, x[ 5],  4, 0xfffa3942); /* 33 */     /* Round 3 */
      HH (d, a, b, c, x[ 8], 11, 0x8771f681); /* 34 */
      HH (c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
      HH (b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
      HH (a, b, c, d, x[ 1],  4, 0xa4beea44); /* 37 */
      HH (d, a, b, c, x[ 4], 11, 0x4bdecfa9); /* 38 */
      HH (c, d, a, b, x[ 7], 16, 0xf6bb4b60); /* 39 */
      HH (b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
      HH (a, b, c, d, x[13],  4, 0x289b7ec6); /* 41 */
      HH (d, a, b, c, x[ 0], 11, 0xeaa127fa); /* 42 */
      HH (c, d, a, b, x[ 3], 16, 0xd4ef3085); /* 43 */
      HH (b, c, d, a, x[ 6], 23, 0x04881d05); /* 44 */
      HH (a, b, c, d, x[ 9],  4, 0xd9d4d039); /* 45 */
      HH (d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
      HH (c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
      HH (b, c, d, a, x[ 2], 23, 0xc4ac5665); /* 48 */

      II (a, b, c, d, x[ 0],  6, 0xf4292244); /* 49 */     /* Round 4 */
      II (d, a, b, c, x[ 7], 10, 0x432aff97); /* 50 */
      II (c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
      II (b, c, d, a, x[ 5], 21, 0xfc93a039); /* 52 */
      II (a, b, c, d, x[12],  6, 0x655b59c3); /* 53 */
      II (d, a, b, c, x[ 3], 10, 0x8f0ccc92); /* 54 */
      II (c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
      II (b, c, d, a, x[ 1], 21, 0x85845dd1); /* 56 */
      II (a, b, c, d, x[ 8],  6, 0x6fa87e4f); /* 57 */
      II (d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
      II (c, d, a, b, x[ 6], 15, 0xa3014314); /* 59 */
      II (b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
      II (a, b, c, d, x[ 4],  6, 0xf7537e82); /* 61 */
      II (d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
      II (c, d, a, b, x[ 2], 15, 0x2ad7d2bb); /* 63 */
      II (b, c, d, a, x[ 9], 21, 0xeb86d391); /* 64 */

      state[0] = a = a + state[0];
      state[1] = b = b + state[1];
      state[2] = c = c + state[2];
      state[3] = d = d + state[3];

      in += 64;
   }
}


/*
   MD5 block update operation:
   Process another sub-string of the message and update the context.
*/
void MD5Update (MD5_CTX *context, const uint8_t *input, size_t inputBytes) {
   int i;
   int byteIndex;
   unsigned int partLen;
   int len;

   /* Compute number of bytes mod 64 */
   byteIndex = (context->count[0] >> 3) & 0x3F;

   /* Update number of bits: count += 8 * inputBytes */
   if ((context->count[0] += inputBytes << 3) < (inputBytes << 3))
      context->count[1]++;
   context->count[1] += (inputBytes >> (32-3));

   partLen = (64 - byteIndex);

   /* Transform as many times as possible. */
   if (inputBytes >= partLen) {
      memcpy (context->buffer + byteIndex, input, partLen);
      __MD5Transform (context->state, (const uint8_t *) context->buffer, 1);
      len = (inputBytes - partLen) / 64;
      __MD5Transform (context->state, &input[partLen], len);
      i = partLen + 64 * len;
      byteIndex = 0;
   } else
      i = 0;

   /* Buffer remaining input */
   memcpy (&context->buffer[byteIndex], &input[i], inputBytes - i);
}

#endif


void MD5Final (uint8_t digest[16], MD5_CTX* context) {
   static uint8_t finalBlock[64];

   uint32_t bits[2];
   int      byteIndex;
   int      finalBlockLength;

   byteIndex = (context->count[0] >> 3) & 0x3F;
   finalBlockLength = ((byteIndex < 56) ? 56 : 120) - byteIndex;
   finalBlock[0] = 0x80;

#if (__BYTE_ORDER == __BIG_ENDIAN)
   CopyToLittleEndian (bits, (const uint8_t *) context->count, 2);
#else
   memcpy(bits, context->count, 8);
#endif

   MD5Update (context, finalBlock, finalBlockLength);
   MD5Update (context, (const uint8_t *) bits, 8);

#if (__BYTE_ORDER == __BIG_ENDIAN)
   CopyToLittleEndian ((uint32_t *) digest, (const uint8_t *) context->state, 4);
#else
   memcpy (digest, context->state, 16);
#endif

   memset(context, 0, sizeof(*context));
}

