/****************************************************************************
 * apps/netutils/codecs/md5.c
 *
 * This file is part of the NuttX RTOS:
 *
 *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
 *   Author: Darcy Gong
 *
 * Reference:
 *
 *   This code implements the MD5 message-digest algorithm.
 *   The algorithm is due to Ron Rivest.  This code was
 *   written by Colin Plumb in 1993, no copyright is claimed.
 *   This code is in the public domain; do with it what you wish.
 *
 *   Equivalent code is available from RSA Data Security, Inc.
 *   This code has been tested against that, and is equivalent,
 *   except that you don't need to include two pages of legalese
 *   with every copy.
 *
 *   To compute the message digest of a chunk of bytes, declare an
 *   md5_context_s structure, pass it to md5_init, call md5_update as
 *   needed on buffers full of bytes, and then call md5_final, which
 *   will fill a supplied 16-byte array with the digest.
 *
 *   See README and COPYING for more details.
 *
 * And is re-released under the NuttX modified BSD license:
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *   3. Neither the name of the Institute nor the names of its contributors
 *      may be used to endorse or promote products derived from this software
 *      without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS''
 *   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 *   THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 *   PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS
 *   BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 *   THE POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

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

#include "netutils/md5.h"

#ifdef CONFIG_CODECS_HASH_MD5

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#  define F1(x, y, z) (z ^ (x & (y ^ z)))
#  define F2(x, y, z) F1(z, x, y)
#  define F3(x, y, z) (x ^ y ^ z)
#  define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */

#  define MD5STEP(f, w, x, y, z, data, s) \
        ( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: byte_reverse
 ****************************************************************************/

#ifndef CONFIG_ENDIAN_BIG
#  define byte_reverse(buf, len)
#else
static void byte_reverse(FAR unsigned char *buf, unsigned longs)
{
  uint32_t t;
  do
    {
      t = ((uint32_t)buf[3] << 24) |
          ((uint32_t)buf[2] << 16) |
          ((uint32_t)buf[1] << 8)  |
           (uint32_t)buf[0];

      *(uint32_t *)buf = t;
      buf += 4;
    }
  while (--longs);
}
#endif

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: md5_init
 *
 * Description:
 *   Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 *   initialization constants.
 *
 ****************************************************************************/

void md5_init(struct md5_context_s *ctx)
{
  ctx->buf[0] = 0x67452301;
  ctx->buf[1] = 0xefcdab89;
  ctx->buf[2] = 0x98badcfe;
  ctx->buf[3] = 0x10325476;

  ctx->bits[0] = 0;
  ctx->bits[1] = 0;
}

/****************************************************************************
 * Name: md5_update
 *
 * Description:
 *   Update context to reflect the concatenation of another buffer full
 *   of bytes.
 *
 ****************************************************************************/

void md5_update(struct md5_context_s *ctx, unsigned char const *buf,
               unsigned len)
{
  uint32_t t;

  /* Update bitcount */

  t = ctx->bits[0];
  if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
    {
      /* Carry from low to high */

      ctx->bits[1]++;
    }

  ctx->bits[1] += len >> 29;

  /* Bytes already in shsInfo->data */

  t = (t >> 3) & 0x3f;

  /* Handle any leading odd-sized chunks */

  if (t)
    {
      unsigned char *p = (unsigned char *)ctx->in + t;

      t = 64 - t;
      if (len < t)
        {
          memcpy(p, buf, len);
          return;
        }

      memcpy(p, buf, t);
      byte_reverse(ctx->in, 16);
      md5_transform(ctx->buf, (uint32_t *) ctx->in);
      buf += t;
      len -= t;
    }

  /* Process data in 64-byte chunks */

  while (len >= 64)
    {
      memcpy(ctx->in, buf, 64);
      byte_reverse(ctx->in, 16);
      md5_transform(ctx->buf, (uint32_t *) ctx->in);
      buf += 64;
      len -= 64;
    }

  /* Handle any remaining bytes of data. */

  memcpy(ctx->in, buf, len);
}

/****************************************************************************
 * Name: md5_final
 *
 * Description:
 *   Final wrapup - pad to 64-byte boundary with the bit pattern
 *   1 0* (64-bit count of bits processed, MSB-first)
 *
 ****************************************************************************/

void md5_final(unsigned char digest[16], struct md5_context_s *ctx)
{
  unsigned count;
  unsigned char *p;

  /* Compute number of bytes mod 64 */

  count = (ctx->bits[0] >> 3) & 0x3f;

  /* Set the first char of padding to 0x80.  This is safe since there is
   * always at least one byte free.
   */

  p = ctx->in + count;
  *p++ = 0x80;

  /* Bytes of padding needed to make 64 bytes */

  count = 64 - 1 - count;

  /* Pad out to 56 mod 64 */

  if (count < 8)
    {
      /* Two lots of padding: Pad the first block to 64 bytes */

      memset(p, 0, count);
      byte_reverse(ctx->in, 16);
      md5_transform(ctx->buf, (uint32_t *) ctx->in);

      /* Now fill the next block with 56 bytes */

      memset(ctx->in, 0, 56);
    }
  else
    {
      /* Pad block to 56 bytes */

      memset(p, 0, count - 8);
    }

  byte_reverse(ctx->in, 14);

  /* Append length in bits and transform */

  ((uint32_t *)ctx->in)[14] = ctx->bits[0];
  ((uint32_t *)ctx->in)[15] = ctx->bits[1];

  md5_transform(ctx->buf, (uint32_t *) ctx->in);
  byte_reverse((unsigned char *)ctx->buf, 4);
  memcpy(digest, ctx->buf, 16);
  memset(ctx, 0, sizeof(struct md5_context_s));  /* In case it's sensitive */
}

/****************************************************************************
 * Name: md5_transform
 *
 * Description:
 *   The core of the MD5 algorithm, this alters an existing MD5 hash to
 *   reflect the addition of 16 longwords of new data. md5_update blocks
 *   the data and converts bytes into longwords for this routine.
 *
 ****************************************************************************/

void md5_transform(uint32_t buf[4], uint32_t const in[16])
{
  register uint32_t a;
  register uint32_t b;
  register uint32_t c;
  register uint32_t d;

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

  MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
  MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
  MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
  MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
  MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
  MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
  MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
  MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
  MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
  MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
  MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
  MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
  MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
  MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
  MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
  MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

  MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
  MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
  MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
  MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
  MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
  MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
  MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
  MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
  MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
  MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
  MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
  MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
  MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
  MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
  MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
  MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

  MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
  MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
  MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
  MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
  MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
  MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
  MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
  MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
  MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
  MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
  MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
  MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
  MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
  MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
  MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
  MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

  MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
  MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
  MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
  MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
  MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
  MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
  MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
  MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
  MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
  MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
  MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
  MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
  MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
  MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
  MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
  MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

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

/****************************************************************************
 * Name: md5_sum
 *
 * Description:
 * MD5 hash for a data block
 *
 * Input Parameters:
 *   addr: Pointers to the data area
 *   len: Lengths of the data block
 *   mac: Buffer for the hash
 *
 ****************************************************************************/

void md5_sum(const uint8_t * addr, const size_t len, uint8_t * mac)
{
  MD5_CTX ctx;

  md5_init(&ctx);
  md5_update(&ctx, addr, len);
  md5_final(mac, &ctx);
}

/****************************************************************************
 * Name: md5_hash
 ****************************************************************************/

char *md5_hash(const uint8_t * addr, const size_t len)
{
  uint8_t digest[16];
  char *hash;
  int i;

  hash = malloc(33);
  md5_sum(addr, len, digest);
  for (i = 0; i < 16; i++)
    {
      sprintf(&hash[i * 2], "%02x", digest[i]);
    }

  hash[32] = 0;
  return hash;
}

#endif /* CONFIG_CODECS_HASH_MD5 */