encfs/fs/NameIO.cpp

/*****************************************************************************
 * Author:   Valient Gough <vgough@pobox.com>
 *
 *****************************************************************************
 * Copyright (c) 2004, Valient Gough
 *
 * This program 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.  
 *
 * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "base/config.h"
#include "base/Error.h"
#include "fs/NameIO.h"

#include <glog/logging.h>

#include <map>
#include <cstring>

// for static build.  Need to reference the modules which are registered at
// run-time, to ensure that the linker doesn't optimize them away.
#include <iostream>
#include "fs/BlockNameIO.h"
#include "fs/StreamNameIO.h"
#include "fs/NullNameIO.h"

using namespace std;

namespace encfs {

#define REF_MODULE(TYPE) \
  do { \
    if(!TYPE::Enabled() ) \
      cerr << "referenceModule: should never happen\n"; \
  } while(0)

static
void AddSymbolReferences()
{
  REF_MODULE(BlockNameIO);
  REF_MODULE(StreamNameIO);
  REF_MODULE(NullNameIO);
}


struct NameIOAlg
{
  bool hidden;
  NameIO::Constructor constructor;
  string description;
  Interface iface;
  bool needsStreamMode;
};

typedef multimap< string, NameIOAlg > NameIOMap_t;
static NameIOMap_t *gNameIOMap = 0;


list< NameIO::Algorithm > NameIO::GetAlgorithmList( bool includeHidden )
{
  AddSymbolReferences();

  list< Algorithm > result;
  if(gNameIOMap)
  {
    NameIOMap_t::const_iterator it;
    NameIOMap_t::const_iterator end = gNameIOMap->end();
    for(it = gNameIOMap->begin(); it != end; ++it)
    {
      if(includeHidden || !it->second.hidden)
      {
        Algorithm tmp;
        tmp.name = it->first;
        tmp.description = it->second.description;
        tmp.iface = it->second.iface;
        tmp.needsStreamMode = it->second.needsStreamMode;

        result.push_back( tmp );
      }
    }
  }

  return result;
}

bool NameIO::Register( const char *name, const char *description,
    const Interface &iface, Constructor constructor,
    bool needsStreamMode,
    bool hidden )
{
  if( !gNameIOMap )
    gNameIOMap = new NameIOMap_t;

  NameIOAlg alg;
  alg.hidden = hidden;
  alg.constructor = constructor;
  alg.description = description;
  alg.iface = iface;
  alg.needsStreamMode = needsStreamMode;

  gNameIOMap->insert( make_pair( string(name), alg ));
  return true;
}

shared_ptr<NameIO> NameIO::New(const string &name, 
                               const shared_ptr<CipherV1> &cipher)
{
  shared_ptr<NameIO> result;
  if(gNameIOMap)
  {
    NameIOMap_t::const_iterator it = gNameIOMap->find( name );
    if(it != gNameIOMap->end())
    {
      Constructor fn = it->second.constructor;
      result = (*fn)( it->second.iface, cipher );
    }
  }
  return result;
}

shared_ptr<NameIO> NameIO::New(const Interface &iface, 
                               const shared_ptr<CipherV1> &cipher)
{
  shared_ptr<NameIO> result;
  if(gNameIOMap)
  {
    NameIOMap_t::const_iterator it;
    NameIOMap_t::const_iterator end = gNameIOMap->end();
    for(it = gNameIOMap->begin(); it != end; ++it)
    {
      if( implements(it->second.iface, iface ))
      {
        Constructor fn = it->second.constructor;
        result = (*fn)( iface, cipher );
        break;
      }
    }
  }
  return result;
}



NameIO::NameIO()
    : chainedNameIV( false ), reverseEncryption( false )
{
}

NameIO::~NameIO()
{
}

void NameIO::setChainedNameIV( bool enable )
{
  chainedNameIV = enable;
}

bool NameIO::getChainedNameIV() const
{
  return chainedNameIV;
}

void NameIO::setReverseEncryption( bool enable )
{
  reverseEncryption = enable;
}

bool NameIO::getReverseEncryption() const
{
  return reverseEncryption;
}


std::string NameIO::recodePath( const char *path, 
    int (NameIO::*_length)(int) const,
    int (NameIO::*_code)(const char*, int, uint64_t *, char*) const,
    uint64_t *iv ) const
{
  string output;

  while( *path )
  {
    if( *path == '/' )
    {
      if( !output.empty() ) // don't start the string with '/'
        output += '/';
      ++path;
    } else
    {
      bool isDotFile = (*path == '.');
      const char *next = strchr( path, '/' );
      int len = next ? next - path : strlen( path );

      // at this point we know that len > 0
      if( isDotFile && (path[len-1] == '.') && (len <= 2) )
      {
        output.append(len, '.'); // append [len] copies of '.'
        path += len;
        continue;
      }

      // figure out buffer sizes
      int approxLen = (this->*_length)( len );
      if(approxLen <= 0)
        throw Error("Filename too small to decode");

      BUFFER_INIT( codeBuf, 32, (unsigned int)approxLen+1 );

      // code the name
      int codedLen = (this->*_code)( path, len, iv, codeBuf );
      rAssert( codedLen <= approxLen );
      rAssert( codeBuf[codedLen] == '\0' );
      path += len;

      // append result to string
      output += (char*)codeBuf;

      BUFFER_RESET( codeBuf );
    }
  }

  return output;
}

std::string NameIO::encodePath( const char *plaintextPath ) const
{
  uint64_t iv = 0;
  return encodePath( plaintextPath, &iv);
}

std::string NameIO::decodePath( const char *cipherPath ) const
{
  uint64_t iv = 0;
  return decodePath( cipherPath, &iv );
}

std::string NameIO::_encodePath( const char *plaintextPath, uint64_t *iv ) const
{
    // if chaining is not enabled, then the iv pointer is not used..
  if(!chainedNameIV)
    iv = 0;
  return recodePath( plaintextPath, 
      &NameIO::maxEncodedNameLen, &NameIO::encodeName, iv);
}

std::string NameIO::_decodePath( const char *cipherPath, uint64_t *iv ) const
{
  // if chaining is not enabled, then the iv pointer is not used..
  if(!chainedNameIV)
    iv = 0;
  return recodePath( cipherPath, 
      &NameIO::maxDecodedNameLen, &NameIO::decodeName, iv);
}

std::string NameIO::encodePath( const char *path, uint64_t *iv ) const
{
  return getReverseEncryption() ? 
    _decodePath( path, iv ) :
    _encodePath( path, iv );
} 

std::string NameIO::decodePath( const char *path, uint64_t *iv ) const
{
  return getReverseEncryption() ? 
    _encodePath( path, iv ) :
    _decodePath( path, iv );
} 


int NameIO::encodeName( const char *input, int length, char *output ) const
{
  return encodeName( input, length, (uint64_t*)0, output );
}

int NameIO::decodeName( const char *input, int length, char *output ) const
{
  return decodeName( input, length, (uint64_t*)0, output );
}

std::string NameIO::_encodeName( const char *plaintextName, int length ) const
{
  int approxLen = maxEncodedNameLen( length );

  BUFFER_INIT( codeBuf, 32, (unsigned int)approxLen+1 );

  // code the name
  int codedLen = encodeName( plaintextName, length, 0, codeBuf );
  rAssert( codedLen <= approxLen );
  rAssert( codeBuf[codedLen] == '\0' );

  // append result to string
  std::string result = (char*)codeBuf;

  BUFFER_RESET( codeBuf );

  return result;
}

std::string NameIO::_decodeName( const char *encodedName, int length ) const
{
  int approxLen = maxDecodedNameLen( length );

  BUFFER_INIT( codeBuf, 32, (unsigned int)approxLen+1 );

  // code the name
  int codedLen = decodeName( encodedName, length, 0, codeBuf );
  rAssert( codedLen <= approxLen );
  rAssert( codeBuf[codedLen] == '\0' );

  // append result to string
  std::string result = (char*)codeBuf;

  BUFFER_RESET( codeBuf );

  return result;
}

std::string NameIO::encodeName( const char *path, int length ) const
{
  return getReverseEncryption() ?
    _decodeName( path, length ) :
    _encodeName( path, length );
}

std::string NameIO::decodeName( const char *path, int length ) const
{
  return getReverseEncryption() ?
    _encodeName( path, length ) :
    _decodeName( path, length );
}

}  // namespace encfs