// @(#)root/base:$Name:  $:$Id: TMD5.cxx,v 1.12 2003/03/06 17:09:42 rdm Exp $
// Author: Fons Rademakers   29/9/2001

/*************************************************************************
 * Copyright (C) 1995-2001, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TMD5                                                                 //
//                                                                      //
// 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, create an         //
// TMD5 object, call Update() as needed on buffers full of bytes, and   //
// then call Final(), which will, optionally, fill a supplied 16-byte   //
// array with the  digest.                                              //
//                                                                      //
//////////////////////////////////////////////////////////////////////////

#include "TMD5.h"
#include "TError.h"
#include "TSystem.h"
#include "Bytes.h"
#include <string.h>
#include <errno.h>
#ifdef R__WIN32
#include <io.h>
#endif

ClassImp(TMD5)

//______________________________________________________________________________
 TMD5::TMD5()
{
   // Create TMD5 object. Set bit count to 0 and buffer to mysterious
   // initialization constants.

   fBuf[0] = 0x67452301;
   fBuf[1] = 0xefcdab89;
   fBuf[2] = 0x98badcfe;
   fBuf[3] = 0x10325476;

   fBits[0] = 0;
   fBits[1] = 0;

   memset(fIn, 0, 64);

   memset(fDigest, 0, 16);
   fFinalized = kFALSE;
}

//______________________________________________________________________________
 TMD5::TMD5(const UChar_t *digest)
{
   // Create finalized TMD5 object containing passed in 16 byte digest.

   if (digest)
      memcpy(fDigest, digest, 16);
   else {
      memset(fDigest, 0, 16);
      Error("TMD5::TMD5", "digest is 0");
   }
   fFinalized = kTRUE;
}

//______________________________________________________________________________
 TMD5::TMD5(const TMD5 &md5)
{
   // MD5 copy ctor. Special copy ctor avoids copying unnecessary
   // temp arrays when finalized.

   if (!md5.fFinalized) {
      memcpy(fBuf,  md5.fBuf,  4*sizeof(UInt_t));
      memcpy(fBits, md5.fBits, 2*sizeof(UInt_t));
      memcpy(fIn,   md5.fIn,   64);
   }

   memcpy(fDigest, md5.fDigest, 16);
   fFinalized = md5.fFinalized;
}

//______________________________________________________________________________
TMD5 &TMD5::operator=(const TMD5 &rhs)
{
   // MD5 assignment operator. Special assignment operator avoids
   // copying unnecessary temp arrays when finalized.

   if (this != &rhs) {
      if (!rhs.fFinalized) {
         memcpy(fBuf,  rhs.fBuf,  4*sizeof(UInt_t));
         memcpy(fBits, rhs.fBits, 2*sizeof(UInt_t));
         memcpy(fIn,   rhs.fIn,   64);
      }
      memcpy(fDigest, rhs.fDigest, 16);
      fFinalized = rhs.fFinalized;
   }
   return *this;
}

//______________________________________________________________________________
 void TMD5::Update(const UChar_t *buf, UInt_t len)
{
   // Update TMD5 object to reflect the concatenation of another buffer full
   // of bytes.

   if (fFinalized) {
      Error("TMD5::Update", "Final() has already been called");
      return;
   }

   UInt_t t;

   // Update bitcount
   t = fBits[0];
   if ((fBits[0] = t + (len << 3)) < t)
      fBits[1]++;        // Carry from low to high
   fBits[1] += len >> 29;

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

   // Handle any leading odd-sized chunks
   if (t) {
      UChar_t *p = (UChar_t *) fIn + t;

      t = 64 - t;
      if (len < t) {
         memcpy(p, buf, len);
         return;
      }
      memcpy(p, buf, t);
      ByteReverse(fIn, 16);
      Transform(fBuf, (UInt_t *) fIn);
      buf += t;
      len -= t;
   }

   // Process data in 64-byte chunks
   while (len >= 64) {
      memcpy(fIn, buf, 64);
      ByteReverse(fIn, 16);
      Transform(fBuf, (UInt_t *) fIn);
      buf += 64;
      len -= 64;
   }

   // Handle any remaining bytes of data
   memcpy(fIn, buf, len);
}

//______________________________________________________________________________
 void TMD5::Final(UChar_t digest[16])
{
   // Final wrapup - pad to 64-byte boundary with the bit patterns
   // 1 0* (64-bit count of bits processed, MSB-first).
   // Returns digest.

   Final();
   memcpy(digest, fDigest, 16);
}

//______________________________________________________________________________
 void TMD5::Final()
{
   // Final wrapup - pad to 64-byte boundary with the bit patterns
   // 1 0* (64-bit count of bits processed, MSB-first).

   if (fFinalized)
      return;

   UInt_t   count;
   UChar_t *p;

   // Compute number of bytes mod 64
   count = (fBits[0] >> 3) & 0x3F;

   // Set the first char of padding to 0x80. This is safe since there is
   // always at least one byte free.
   p = fIn + 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);
      ByteReverse(fIn, 16);
      Transform(fBuf, (UInt_t *) fIn);

      // Now fill the next block with 56 bytes
      memset(fIn, 0, 56);
   } else {
      // Pad block to 56 bytes
      memset(p, 0, count - 8);
   }
   ByteReverse(fIn, 14);

   // Append length in bits and transform
   ((UInt_t *) fIn)[14] = fBits[0];
   ((UInt_t *) fIn)[15] = fBits[1];

   Transform(fBuf, (UInt_t *) fIn);
   ByteReverse((UChar_t *) fBuf, 4);
   memcpy(fDigest, fBuf, 16);

   fFinalized = kTRUE;
}

//______________________________________________________________________________
 void TMD5::Print() const
{
   // Print digest in ascii hex form.

   if (!fFinalized) {
      Error("TMD5::Print", "Final() has not yet been called");
      return;
   }

   for (int i = 0; i < 16; i++)
      printf("%.2hx", (UShort_t)fDigest[i]);
   printf("n");
}

//______________________________________________________________________________
 const char *TMD5::AsString() const
{
   // Return message digest as string. Returns "" in case Final() has
   // not yet been called. Copy result because it points to a statically
   // allocated string.

   if (!fFinalized) {
      Error("TMD5::AsString", "Final() has not yet been called");
      return "";
   }

   static char s[33];

   for (int i = 0; i < 16; i++)
      sprintf((s+2*i), "%.2hx", (UShort_t)fDigest[i]);
   s[32] = 0;

   return s;
}

//______________________________________________________________________________
 void TMD5::ByteReverse(UChar_t *buf, UInt_t longs)
{
#ifdef R__BYTESWAP
   UInt_t t;
   do {
      t = host2net(*(UInt_t *)buf);
      *(UInt_t *) buf = t;
      buf += 4;
   } while (--longs);
#else
   if (buf || longs) { }
#endif
}


// 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 )

//______________________________________________________________________________
 void TMD5::Transform(UInt_t buf[4], const UInt_t in[16])
{
   // The core of the MD5 algorithm, this alters an existing MD5 hash to
   // reflect the addition of 16 longwords of new data. Update() blocks
   // the data and converts bytes into longwords for this routine.

    register UInt_t a, b, c, 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;
}

//______________________________________________________________________________
Bool_t operator==(const TMD5 &m1, const TMD5 &m2)
{
   // Compare two message digests for equality.

   // Make sure both are finalized.
   if (!m1.fFinalized || !m2.fFinalized) {
      if (!m1.fFinalized)
         Error("TMD5::operator==(const TMD5&, const TMD5&)", "arg1.Final() not yet called");
      if (!m2.fFinalized)
         Error("TMD5::operator==(const TMD5&, const TMD5&)", "arg2.Final() not yet called");
      return kFALSE;
   }

   for (int i = 0; i < 16; i++)
      if (m1.fDigest[i] != m2.fDigest[i])
         return kFALSE;

   return kTRUE;
}

//______________________________________________________________________________
 TMD5 *TMD5::ReadChecksum(const char *file)
{
   // Returns checksum stored in ASCII in specified file. Use to read files
   // created via WriteChecksum(). The returned TMD5 object must be deleted
   // by the user. Returns 0 in case the file cannot be opened or in case of
   // error. Static utlity function.

   FILE *fid = fopen(file, "r");
   if (!fid) {
      // file cannot be opened
      return 0;
   }

   char buf[33];

   fgets(buf, 33, fid);

   UChar_t digest[16];
   for (int i = 0; i < 16; i++) {
      UShort_t d;
      char s = buf[2+2*i];
      buf[2+2*i] = 0;
      sscanf(buf+2*i, "%hx", &d);
      buf[2+2*i] = s;
      digest[i] = (UChar_t) d;
   }

   fclose(fid);

   TMD5 *md5 = new TMD5(digest);
   return md5;
}

//______________________________________________________________________________
 Int_t TMD5::WriteChecksum(const char *file, const TMD5 *md5)
{
   // Writes checksum in ASCII format to specified file. This file can
   // directly be read by ReadChecksum(). The md5 must have been finalized.
   // Returns -1 in case file cannot be opened or in case of error,
   // 0 otherwise. Static utility function.

   FILE *fid = fopen(file, "w");
   if (!fid) {
      // file cannot be opened
      return -1;
   }

   fputs(md5->AsString(), fid);

   fclose(fid);

   return 0;
}

//______________________________________________________________________________
 TMD5 *TMD5::FileChecksum(const char *file)
{
   // Returns checksum of specified file. The returned TMD5 object must
   // be deleted by the user. Returns 0 in case the file does not exists
   // or in case of error. This function preserves the modtime of the file
   // so it can be safely used in conjunction with methods that keep track
   // of the file's modtime. Static utility function.

   Long_t id, size, flags, modtime;
   if (gSystem->GetPathInfo(file, &id, &size, &flags, &modtime) == 0) {
      if (flags > 1) {
         Error("TMD5::FileChecksum", "%s not a regular file (%ld)", file, flags);
         return 0;
      }
   } else {
      // file does not exist
      return 0;
   }

#ifndef WIN32
   Int_t fd = open(file, O_RDONLY);
#else
   Int_t fd = open(file, O_RDONLY | O_BINARY);
#endif
   if (fd < 0) {
      Error("TMD5::FileChecksum", "cannot open %s in read mode", file);
      return 0;
   }

   TMD5 *md5 = new TMD5;

   Seek_t pos = 0;
   const Int_t bufSize = 8192;
   UChar_t buf[bufSize];

   while (pos < size) {
      Seek_t left = Seek_t(size - pos);
      if (left > bufSize)
         left = bufSize;
      Int_t siz;
      while ((siz = read(fd, buf, left)) < 0 && TSystem::GetErrno() == EINTR)
         TSystem::ResetErrno();
      if (siz < 0 || siz != left) {
         Error("TMD5::FileChecksum", "error reading from file %s", file);
         close(fd);
         delete md5;
         return 0;
      }

      md5->Update(buf, left);

      pos += left;
   }

   close(fd);

   md5->Final();

   gSystem->Utime(file, modtime, modtime);

   return md5;
}

//______________________________________________________________________________
 Int_t TMD5::FileChecksum(const char *file, UChar_t digest[16])
{
   // Returns checksum of specified file in digest argument. Returns -1 in
   // case of error, 0 otherwise. This method preserves the modtime of the
   // file so it can be safely used in conjunction with methods that keep
   // track of the file's modtime. Static utility function.

   TMD5 *md5 = FileChecksum(file);
   if (md5) {
      memcpy(digest, md5->fDigest, 16);
      delete md5;
      return 0;
   } else
      memset(digest, 0, 16);

   return -1;
}