Digest.cc

Go to the documentation of this file.

#include <iomanip>
#include <sstream>

#include "FWCore/Utilities/interface/EDMException.h"
#include "FWCore/Utilities/interface/Digest.h"

namespace cms
{
  namespace
  {
    MD5Result const& invalidResult()
    {
      static const MD5Result val;      
      return val;
    }

    char unhexify(char hexed)
    {
      switch (hexed) 
    {
    case '0': case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9':
      return hexed - '0';
    case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
      return hexed - 'a' + 10;
    case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
      return hexed - 'A' + 10;
    default:
      throw edm::Exception(edm::errors::LogicError)
        << "Non-hex character in Hash "
        << "Please report this to the core framework developers";
    }
      // We never get here; return put in place to calm the compiler's
      // anxieties.
      return '\0';
    }
  }

  //--------------------------------------------------------------------
  //
  // MD5Result and associated free functions
  //

  void set_to_default(MD5Result& val)
  {
    val.bytes[0] = 0xd4;
    val.bytes[1] = 0x1d;
    val.bytes[2] = 0x8c;
    val.bytes[3] = 0xd9;
    val.bytes[4] = 0x8f;
    val.bytes[5] = 0x00;
    val.bytes[6] = 0xb2;
    val.bytes[7] = 0x04;
    val.bytes[8] = 0xe9;
    val.bytes[9] = 0x80;
    val.bytes[10] = 0x09;
    val.bytes[11] = 0x98;
    val.bytes[12] = 0xec;
    val.bytes[13] = 0xf8;
    val.bytes[14] = 0x42;
    val.bytes[15] = 0x7e;
  }

  MD5Result::MD5Result() 
  {
    set_to_default(*this);
  }

  static const char * s_hexValues =
  "000102030405060708090a0b0c0d0e0f"
  "101112131415161718191a1b1c1d1e1f"
  "202122232425262728292a2b2c2d2e2f"
  "303132333435363738393a3b3c3d3e3f"
  "404142434445464748494a4b4c4d4e4f"
  "505152535455565758595a5b5c5d5e5f"
  "606162636465666768696a6b6c6d6e6f"
  "707172737475767778797a7b7c7d7e7f"
  "808182838485868788898a8b8c8d8e8f"
  "909192939495969798999a9b9c9d9e9f"
  "a0a1a2a3a4a5a6a7a8a9aaabacadaeaf"
  "b0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
  "c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"
  "d0d1d2d3d4d5d6d7d8d9dadbdcdddedf"
  "e0e1e2e3e4e5e6e7e8e9eaebecedeeef"
  "f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff";

  std::string MD5Result::toString() const
  {
    char buf[16*2];
    char* pBuf=buf;
    for(unsigned int i=0; i<sizeof(bytes);++i){
      const char* p = s_hexValues+2*bytes[i];
      *pBuf = *p;
      ++pBuf;
      ++p;
      *pBuf=*p;
      ++pBuf;
    }
    return std::string(buf, sizeof(buf));
  }

  std::string MD5Result::compactForm() const
  {
    // This is somewhat dangerous, because the conversion of 'unsigned
    // char' to 'char' may be undefined if 'char' is a signed type
    // (4.7p3 in the Standard).
    const char* p = reinterpret_cast<const char*>(&bytes[0]);
    return std::string(p, p+sizeof(bytes));
  }

  void MD5Result::fromHexifiedString(std::string const& hexy)
  {
    switch (hexy.size())
      {
      case 0:
    {
      set_to_default(*this);
    }
    break;
      case 32:
    {
      std::string::const_iterator it = hexy.begin();
      for (size_t i = 0; i != 16; ++i)
        {
          // first nybble
          bytes[i] = ( unhexify(*it++) << 4 );
          // second nybble
          bytes[i] += ( unhexify(*it++) );
        }
    }
    break;
      default:
    {
      // Not really sure of what sort of exception to throw...
      throw edm::Exception(edm::errors::LogicError)
        << "String of illegal length: "
        << hexy.size()
        << " given to MD5Result::fromHexifiedString";     
    }
      }
  }

  bool MD5Result::isValid() const
  {
    return (*this != invalidResult());
  }

  bool operator==(MD5Result const& a, MD5Result const& b)
  {
    return std::equal(a.bytes, a.bytes+sizeof(a.bytes), b.bytes);
  }


  bool operator< (MD5Result const& a, MD5Result const& b)
  {
    return std::lexicographical_compare(a.bytes, 
                    a.bytes+sizeof(a.bytes), 
                    b.bytes,
                    b.bytes+sizeof(b.bytes));
  }



  //--------------------------------------------------------------------
  //
  // Digest
  //

  Digest::Digest() :
    state_()
  {
    md5_init(&state_);
  }

  Digest::Digest(std::string const& s) :
    state_()
  {
    md5_init(&state_);
    this->append(s);
  }

  void Digest::append(std::string const& s) 
  {
    const md5_byte_t* data = reinterpret_cast<const md5_byte_t*>(s.data());
    md5_append(&state_, const_cast<md5_byte_t*>(data), s.size());
  }

  void Digest::append(const char *s, size_t size)
  {
    const md5_byte_t* data = reinterpret_cast<const md5_byte_t*>(s);
    md5_append(&state_, const_cast<md5_byte_t*>(data), size);
  }

  MD5Result Digest::digest() const
  {
    MD5Result aDigest;
    md5_finish(&state_, aDigest.bytes);
    return aDigest;
  }
}