/**********
This library 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 3 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library 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 library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2020 Live Networks, Inc.  All rights reserved.
// Because MD5 may not be implemented (at least, with the same interface) on all systems,
// we have our own implementation.
// Implementation

#include "ourMD5.hh"
#include <NetCommon.h> // for u_int32_t, u_int64_t
#include <string.h>

#define DIGEST_SIZE_IN_BYTES 16
#define DIGEST_SIZE_IN_HEX_DIGITS (2*DIGEST_SIZE_IN_BYTES)
#define DIGEST_SIZE_AS_STRING (DIGEST_SIZE_IN_HEX_DIGITS+1)

// The state of a MD5 computation in progress:

class MD5Context {
public:
  MD5Context();
  ~MD5Context();

  void addData(unsigned char const* inputData, unsigned inputDataSize);
  void end(char* outputDigest /*must point to an array of size DIGEST_SIZE_AS_STRING*/);
  void finalize(unsigned char* outputDigestInBytes);
      // Like "end()", except that the argument is a byte array, of size DIGEST_SIZE_IN_BYTES.
      // This function is used to implement "end()".

private:
  void zeroize(); // to remove potentially sensitive information
  void transform64Bytes(unsigned char const block[64]); // does the actual MD5 transform

private:
  u_int32_t fState[4]; // ABCD
  u_int64_t fBitCount; // number of bits, modulo 2^64
  unsigned char fWorkingBuffer[64];
};

char* our_MD5Data(unsigned char const* data, unsigned dataSize, char* outputDigest) {
  MD5Context ctx;

  ctx.addData(data, dataSize);

  if (outputDigest == NULL) outputDigest = new char[DIGEST_SIZE_AS_STRING];
  ctx.end(outputDigest);

  return outputDigest;
}

unsigned char* our_MD5DataRaw(unsigned char const* data, unsigned dataSize,
			      unsigned char* outputDigest) {
  MD5Context ctx;

  ctx.addData(data, dataSize);

  if (outputDigest == NULL) outputDigest = new unsigned char[DIGEST_SIZE_IN_BYTES];
  ctx.finalize(outputDigest);

  return outputDigest;
}


////////// MD5Context implementation //////////

MD5Context::MD5Context()
  : fBitCount(0) {
  // Initialize with magic constants:
  fState[0] = 0x67452301;
  fState[1] = 0xefcdab89;
  fState[2] = 0x98badcfe;
  fState[3] = 0x10325476;
}

MD5Context::~MD5Context() {
  zeroize();
}

void MD5Context::addData(unsigned char const* inputData, unsigned inputDataSize) {
  // Begin by noting how much of our 64-byte working buffer remains unfilled:
  u_int64_t const byteCount = fBitCount>>3;
  unsigned bufferBytesInUse = (unsigned)(byteCount&0x3F);
  unsigned bufferBytesRemaining = 64 - bufferBytesInUse;

  // Then update our bit count:
  fBitCount += inputDataSize<<3;

  unsigned i = 0;
  if (inputDataSize >= bufferBytesRemaining) {
    // We have enough input data to do (64-byte) MD5 transforms.
    // Do this now, starting with a transform on our working buffer, then with
    // (as many as possible) transforms on rest of the input data.

    memcpy((unsigned char*)&fWorkingBuffer[bufferBytesInUse], (unsigned char*)inputData, bufferBytesRemaining);
    transform64Bytes(fWorkingBuffer);
    bufferBytesInUse = 0;

    for (i = bufferBytesRemaining; i + 63 < inputDataSize; i += 64) {
      transform64Bytes(&inputData[i]);
    }
  }

  // Copy any remaining (and currently un-transformed) input data into our working buffer:
  if (i < inputDataSize) {
    memcpy((unsigned char*)&fWorkingBuffer[bufferBytesInUse], (unsigned char*)&inputData[i], inputDataSize - i);
  }
}

void MD5Context::end(char* outputDigest) {
  unsigned char digestInBytes[DIGEST_SIZE_IN_BYTES];
  finalize(digestInBytes);

  // Convert the digest from bytes (binary) to hex digits:
  static char const hex[]="0123456789abcdef";
  unsigned i;
  for (i = 0; i < DIGEST_SIZE_IN_BYTES; ++i) {
    outputDigest[2*i] = hex[digestInBytes[i] >> 4];
    outputDigest[2*i+1] = hex[digestInBytes[i] & 0x0F];
  }
  outputDigest[2*i] = '\0';
}

// Routines that unpack 32 and 64-bit values into arrays of bytes (in little-endian order).
// (These are used to implement "finalize()".)

static void unpack32(unsigned char out[4], u_int32_t in) {
  for (unsigned i = 0; i < 4; ++i) {
    out[i] = (unsigned char)((in>>(8*i))&0xFF);
  }
}

static void unpack64(unsigned char out[8], u_int64_t in) {
  for (unsigned i = 0; i < 8; ++i) {
    out[i] = (unsigned char)((in>>(8*i))&0xFF);
  }
}

static unsigned char const 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
};

void MD5Context::finalize(unsigned char* outputDigestInBytes) {
  // Unpack our bit count:
  unsigned char bitCountInBytes[8];
  unpack64(bitCountInBytes, fBitCount);

  // Before 'finalizing', make sure that we transform any remaining bytes in our working buffer:
  u_int64_t const byteCount = fBitCount>>3;
  unsigned bufferBytesInUse = (unsigned)(byteCount&0x3F);
  unsigned numPaddingBytes
    = (bufferBytesInUse < 56) ? (56 - bufferBytesInUse) : (64 + 56 - bufferBytesInUse);
  addData(PADDING, numPaddingBytes);

  addData(bitCountInBytes, 8);

  // Unpack our 'state' into the output digest:
  unpack32(&outputDigestInBytes[0], fState[0]);
  unpack32(&outputDigestInBytes[4], fState[1]);
  unpack32(&outputDigestInBytes[8], fState[2]);
  unpack32(&outputDigestInBytes[12], fState[3]);

  zeroize();
}

void MD5Context::zeroize() {
  fState[0] = fState[1] = fState[2] = fState[3] = 0;
  fBitCount = 0;
  for (unsigned i = 0; i < 64; ++i) fWorkingBuffer[i] = 0;
}


////////// Implementation of the MD5 transform ("MD5Context::transform64Bytes()") //////////

// Constants for the transform:
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

// Basic MD5 functions:
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

// Rotate "x" left "n" bits:
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

// Other transforms:
#define FF(a, b, c, d, x, s, ac) { \
 (a) += F((b), (c), (d)) + (x) + (u_int32_t)(ac); \
 (a) = ROTATE_LEFT((a), (s)); \
 (a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) { \
 (a) += G((b), (c), (d)) + (x) + (u_int32_t)(ac); \
 (a) = ROTATE_LEFT((a), (s)); \
 (a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) { \
 (a) += H((b), (c), (d)) + (x) + (u_int32_t)(ac); \
 (a) = ROTATE_LEFT((a), (s)); \
 (a) += (b); \
}
#define II(a, b, c, d, x, s, ac) { \
 (a) += I((b), (c), (d)) + (x) + (u_int32_t)(ac); \
 (a) = ROTATE_LEFT((a), (s)); \
 (a) += (b); \
}

void MD5Context::transform64Bytes(unsigned char const block[64]) {
  u_int32_t a = fState[0], b = fState[1], c = fState[2], d = fState[3];

  // Begin by packing "block" into an array ("x") of 16 32-bit values (in little-endian order):
  u_int32_t x[16];
  for (unsigned i = 0, j = 0; i < 16; ++i, j += 4) {
    x[i] = ((u_int32_t)block[j]) | (((u_int32_t)block[j+1]) << 8) | (((u_int32_t)block[j+2]) << 16) | (((u_int32_t)block[j+3]) << 24);
  }

  // Now, perform the transform on the array "x":

  // Round 1
  FF(a, b, c, d, x[0], S11, 0xd76aa478);	// 1
  FF(d, a, b, c, x[1], S12, 0xe8c7b756);	// 2
  FF(c, d, a, b, x[2], S13, 0x242070db);	// 3
  FF(b, c, d, a, x[3], S14, 0xc1bdceee);	// 4
  FF(a, b, c, d, x[4], S11, 0xf57c0faf);	// 5
  FF(d, a, b, c, x[5], S12, 0x4787c62a);	// 6
  FF(c, d, a, b, x[6], S13, 0xa8304613);	// 7
  FF(b, c, d, a, x[7], S14, 0xfd469501);	// 8
  FF(a, b, c, d, x[8], S11, 0x698098d8);	// 9
  FF(d, a, b, c, x[9], S12, 0x8b44f7af);	// 10
  FF(c, d, a, b, x[10], S13, 0xffff5bb1);	// 11
  FF(b, c, d, a, x[11], S14, 0x895cd7be);	// 12
  FF(a, b, c, d, x[12], S11, 0x6b901122);	// 13
  FF(d, a, b, c, x[13], S12, 0xfd987193);	// 14
  FF(c, d, a, b, x[14], S13, 0xa679438e);	// 15
  FF(b, c, d, a, x[15], S14, 0x49b40821);	// 16
  
  // Round 2
  GG(a, b, c, d, x[1], S21, 0xf61e2562);	// 17
  GG(d, a, b, c, x[6], S22, 0xc040b340);	// 18
  GG(c, d, a, b, x[11], S23, 0x265e5a51);	// 19
  GG(b, c, d, a, x[0], S24, 0xe9b6c7aa);	// 20
  GG(a, b, c, d, x[5], S21, 0xd62f105d);	// 21
  GG(d, a, b, c, x[10], S22, 0x2441453);	// 22
  GG(c, d, a, b, x[15], S23, 0xd8a1e681);	// 23
  GG(b, c, d, a, x[4], S24, 0xe7d3fbc8);	// 24
  GG(a, b, c, d, x[9], S21, 0x21e1cde6);	// 25
  GG(d, a, b, c, x[14], S22, 0xc33707d6);	// 26
  GG(c, d, a, b, x[3], S23, 0xf4d50d87);	// 27
  GG(b, c, d, a, x[8], S24, 0x455a14ed);	// 28
  GG(a, b, c, d, x[13], S21, 0xa9e3e905);	// 29
  GG(d, a, b, c, x[2], S22, 0xfcefa3f8);	// 30
  GG(c, d, a, b, x[7], S23, 0x676f02d9);	// 31
  GG(b, c, d, a, x[12], S24, 0x8d2a4c8a);	// 32
  
  // Round 3
  HH(a, b, c, d, x[5], S31, 0xfffa3942);	// 33
  HH(d, a, b, c, x[8], S32, 0x8771f681);	// 34
  HH(c, d, a, b, x[11], S33, 0x6d9d6122);	// 35
  HH(b, c, d, a, x[14], S34, 0xfde5380c);	// 36
  HH(a, b, c, d, x[1], S31, 0xa4beea44);	// 37
  HH(d, a, b, c, x[4], S32, 0x4bdecfa9);	// 38
  HH(c, d, a, b, x[7], S33, 0xf6bb4b60);	// 39
  HH(b, c, d, a, x[10], S34, 0xbebfbc70);	// 40
  HH(a, b, c, d, x[13], S31, 0x289b7ec6);	// 41
  HH(d, a, b, c, x[0], S32, 0xeaa127fa);	// 42
  HH(c, d, a, b, x[3], S33, 0xd4ef3085);	// 43
  HH(b, c, d, a, x[6], S34, 0x4881d05);	// 44
  HH(a, b, c, d, x[9], S31, 0xd9d4d039);	// 45
  HH(d, a, b, c, x[12], S32, 0xe6db99e5);	// 46
  HH(c, d, a, b, x[15], S33, 0x1fa27cf8);	// 47
  HH(b, c, d, a, x[2], S34, 0xc4ac5665);	// 48
  
  // Round 4
  II(a, b, c, d, x[0], S41, 0xf4292244);	// 49
  II(d, a, b, c, x[7], S42, 0x432aff97);	// 50
  II(c, d, a, b, x[14], S43, 0xab9423a7);	// 51
  II(b, c, d, a, x[5], S44, 0xfc93a039);	// 52
  II(a, b, c, d, x[12], S41, 0x655b59c3);	// 53
  II(d, a, b, c, x[3], S42, 0x8f0ccc92);	// 54
  II(c, d, a, b, x[10], S43, 0xffeff47d);	// 55
  II(b, c, d, a, x[1], S44, 0x85845dd1);	// 56
  II(a, b, c, d, x[8], S41, 0x6fa87e4f);	// 57
  II(d, a, b, c, x[15], S42, 0xfe2ce6e0);	// 58
  II(c, d, a, b, x[6], S43, 0xa3014314);	// 59
  II(b, c, d, a, x[13], S44, 0x4e0811a1);	// 60
  II(a, b, c, d, x[4], S41, 0xf7537e82);	// 61
  II(d, a, b, c, x[11], S42, 0xbd3af235);	// 62
  II(c, d, a, b, x[2], S43, 0x2ad7d2bb);	// 63
  II(b, c, d, a, x[9], S44, 0xeb86d391);	// 64
  
  fState[0] += a; fState[1] += b; fState[2] += c; fState[3] += d;

  // Zeroize sensitive information.
  for (unsigned k = 0; k < 16; ++k) x[k] = 0;
}