/*

 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>

 *

 * Permission is hereby granted, free of charge, to any person obtaining 

 * a copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, sublicense, and/or sell copies of the Software, and to

 * permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice shall be 

 * included in all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS

 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN

 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE.

 */

#include "inner.h"

#define F(B, C, D)     ((((C) ^ (D)) & (B)) ^ (D))

#define G(B, C, D)     ((((C) ^ (B)) & (D)) ^ (C))

#define H(B, C, D)     ((B) ^ (C) ^ (D))

#define I(B, C, D)     ((C) ^ ((B) | ~(D)))

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

/* see inner.h */

const uint32_t br_md5_IV[4] = {

  0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476

};

static const uint32_t K[64] = {

  0xD76AA478, 0xE8C7B756, 0x242070DB, 0xC1BDCEEE,

  0xF57C0FAF, 0x4787C62A, 0xA8304613, 0xFD469501,

  0x698098D8, 0x8B44F7AF, 0xFFFF5BB1, 0x895CD7BE,

  0x6B901122, 0xFD987193, 0xA679438E, 0x49B40821,

  0xF61E2562, 0xC040B340, 0x265E5A51, 0xE9B6C7AA,

  0xD62F105D, 0x02441453, 0xD8A1E681, 0xE7D3FBC8,

  0x21E1CDE6, 0xC33707D6, 0xF4D50D87, 0x455A14ED,

  0xA9E3E905, 0xFCEFA3F8, 0x676F02D9, 0x8D2A4C8A,

  0xFFFA3942, 0x8771F681, 0x6D9D6122, 0xFDE5380C,

  0xA4BEEA44, 0x4BDECFA9, 0xF6BB4B60, 0xBEBFBC70,

  0x289B7EC6, 0xEAA127FA, 0xD4EF3085, 0x04881D05,

  0xD9D4D039, 0xE6DB99E5, 0x1FA27CF8, 0xC4AC5665,

  0xF4292244, 0x432AFF97, 0xAB9423A7, 0xFC93A039,

  0x655B59C3, 0x8F0CCC92, 0xFFEFF47D, 0x85845DD1,

  0x6FA87E4F, 0xFE2CE6E0, 0xA3014314, 0x4E0811A1,

  0xF7537E82, 0xBD3AF235, 0x2AD7D2BB, 0xEB86D391

};

static const unsigned char MP[48] = {

  1, 6, 11, 0, 5, 10, 15, 4, 9, 14, 3, 8, 13, 2, 7, 12,

  5, 8, 11, 14, 1, 4, 7, 10, 13, 0, 3, 6, 9, 12, 15, 2,

  0, 7, 14, 5, 12, 3, 10, 1, 8, 15, 6, 13, 4, 11, 2, 9

};

/* see inner.h */

void

br_md5_round(const unsigned char *buf, uint32_t *val)

{

  uint32_t m[16];

  uint32_t a, b, c, d;

  int i;

  a = val[0];

  b = val[1];

  c = val[2];

  d = val[3];

  /* obsolete

  for (i = 0; i < 16; i ++) {

    m[i] = br_dec32le(buf + (i << 2));

  }

  */

  br_range_dec32le(m, 16, buf);

  for (i = 0; i < 16; i += 4) {

    a = b + ROTL(a + F(b, c, d) + m[i + 0] + K[i + 0],  7);

    d = a + ROTL(d + F(a, b, c) + m[i + 1] + K[i + 1], 12);

    c = d + ROTL(c + F(d, a, b) + m[i + 2] + K[i + 2], 17);

    b = c + ROTL(b + F(c, d, a) + m[i + 3] + K[i + 3], 22);

  }

  for (i = 16; i < 32; i += 4) {

    a = b + ROTL(a + G(b, c, d) + m[MP[i - 16]] + K[i + 0],  5);

    d = a + ROTL(d + G(a, b, c) + m[MP[i - 15]] + K[i + 1],  9);

    c = d + ROTL(c + G(d, a, b) + m[MP[i - 14]] + K[i + 2], 14);

    b = c + ROTL(b + G(c, d, a) + m[MP[i - 13]] + K[i + 3], 20);

  }

  for (i = 32; i < 48; i += 4) {

    a = b + ROTL(a + H(b, c, d) + m[MP[i - 16]] + K[i + 0],  4);

    d = a + ROTL(d + H(a, b, c) + m[MP[i - 15]] + K[i + 1], 11);

    c = d + ROTL(c + H(d, a, b) + m[MP[i - 14]] + K[i + 2], 16);

    b = c + ROTL(b + H(c, d, a) + m[MP[i - 13]] + K[i + 3], 23);

  }

  for (i = 48; i < 64; i += 4) {

    a = b + ROTL(a + I(b, c, d) + m[MP[i - 16]] + K[i + 0],  6);

    d = a + ROTL(d + I(a, b, c) + m[MP[i - 15]] + K[i + 1], 10);

    c = d + ROTL(c + I(d, a, b) + m[MP[i - 14]] + K[i + 2], 15);

    b = c + ROTL(b + I(c, d, a) + m[MP[i - 13]] + K[i + 3], 21);

  }

  val[0] += a;

  val[1] += b;

  val[2] += c;

  val[3] += d;

}

/* see bearssl.h */

void

br_md5_init(br_md5_context *cc)

{

  cc->vtable = &br_md5_vtable;

  memcpy(cc->val, br_md5_IV, sizeof cc->val);

  cc->count = 0;

}

/* see bearssl.h */

void

br_md5_update(br_md5_context *cc, const void *data, size_t len)

{

  const unsigned char *buf;

  size_t ptr;

  buf = data;

  ptr = (size_t)cc->count & 63;

  while (len > 0) {

    size_t clen;

    clen = 64 - ptr;

    if (clen > len) {

      clen = len;

    }

    memcpy(cc->buf + ptr, buf, clen);

    ptr += clen;

    buf += clen;

    len -= clen;

    cc->count += (uint64_t)clen;

    if (ptr == 64) {

      br_md5_round(cc->buf, cc->val);

      ptr = 0;

    }

  }

}

/* see bearssl.h */

void

br_md5_out(const br_md5_context *cc, void *dst)

{

  unsigned char buf[64];

  uint32_t val[4];

  size_t ptr;

  ptr = (size_t)cc->count & 63;

  memcpy(buf, cc->buf, ptr);

  memcpy(val, cc->val, sizeof val);

  buf[ptr ++] = 0x80;

  if (ptr > 56) {

    memset(buf + ptr, 0, 64 - ptr);

    br_md5_round(buf, val);

    memset(buf, 0, 56);

  } else {

    memset(buf + ptr, 0, 56 - ptr);

  }

  br_enc64le(buf + 56, cc->count << 3);

  br_md5_round(buf, val);

  br_range_enc32le(dst, val, 4);

}

/* see bearssl.h */

uint64_t

br_md5_state(const br_md5_context *cc, void *dst)

{

  br_range_enc32le(dst, cc->val, 4);

  return cc->count;

}

/* see bearssl.h */

void

br_md5_set_state(br_md5_context *cc, const void *stb, uint64_t count)

{

  br_range_dec32le(cc->val, 4, stb);

  cc->count = count;

}

/* see bearssl.h */

const br_hash_class br_md5_vtable = {

  sizeof(br_md5_context),

  BR_HASHDESC_ID(br_md5_ID)

    | BR_HASHDESC_OUT(16)

    | BR_HASHDESC_STATE(16)

    | BR_HASHDESC_LBLEN(6)

    | BR_HASHDESC_MD_PADDING,

  (void (*)(const br_hash_class **))&br_md5_init,

  (void (*)(const br_hash_class **, const void *, size_t))&br_md5_update,

  (void (*)(const br_hash_class *const *, void *))&br_md5_out,

  (uint64_t (*)(const br_hash_class *const *, void *))&br_md5_state,

  (void (*)(const br_hash_class **, const void *, uint64_t))

    &br_md5_set_state

};