encfs/fs/NameIO.h

/*****************************************************************************
 * 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/>.
 */

#ifndef _NameIO_incl_
#define _NameIO_incl_

#include <string>
#include <list>

#include <inttypes.h>

#include "base/Interface.h"
#include "base/shared_ptr.h"

namespace encfs {

class CipherV1;

class NameIO
{
 public:
  typedef shared_ptr<NameIO> (*Constructor)(const Interface &iface,
                                            const shared_ptr<CipherV1> &cipher);

  struct Algorithm
  {
    std::string name;
    std::string description;
    Interface iface;
    bool needsStreamMode;
  };

  typedef std::list<Algorithm> AlgorithmList;
  static AlgorithmList GetAlgorithmList( bool includeHidden = false );

  static shared_ptr<NameIO> New(const Interface &iface,
                                const shared_ptr<CipherV1> &cipher);
  static shared_ptr<NameIO> New(const std::string &name,
                                const shared_ptr<CipherV1> &cipher);

  static bool Register( const char *name, const char *description,
                       const Interface &iface, Constructor constructor, 
                       bool needsStreamMode,
                       bool hidden = false);


  NameIO();
  virtual ~NameIO();

  virtual Interface interface() const =0;

  void setChainedNameIV( bool enable );
  bool getChainedNameIV() const;
  void setReverseEncryption( bool enable );
  bool getReverseEncryption() const;

  std::string encodePath( const char *plaintextPath ) const;
  std::string decodePath( const char *encodedPath ) const;

  std::string encodePath( const char *plaintextPath, uint64_t *iv ) const;
  std::string decodePath( const char *encodedPath, uint64_t *iv ) const;

  virtual int maxEncodedNameLen( int plaintextNameLen ) const =0;
  virtual int maxDecodedNameLen( int encodedNameLen ) const =0;

  std::string encodeName( const char *plaintextName, int length ) const;
  std::string decodeName( const char *encodedName, int length ) const;

 protected:	                    
  virtual int encodeName( const char *plaintextName, int length,
                         char *encodedName ) const;
  virtual int decodeName( const char *encodedName, int length,
                         char *plaintextName ) const;

  virtual int encodeName( const char *plaintextName, int length,
                         uint64_t *iv, char *encodedName ) const =0;
  virtual int decodeName( const char *encodedName, int length,
                         uint64_t *iv, char *plaintextName ) const =0;


 private:

  std::string recodePath( const char *path,
                         int (NameIO::*codingLen)(int) const,
                         int (NameIO::*codingFunc)(const char *, int, 
                                                   uint64_t *, char *) const,
                         uint64_t *iv ) const;

  std::string _encodePath( const char *plaintextPath, uint64_t *iv ) const;
  std::string _decodePath( const char *encodedPath, uint64_t *iv ) const;
  std::string _encodeName( const char *plaintextName, int length ) const;
  std::string _decodeName( const char *encodedName, int length ) const;

  bool chainedNameIV;
  bool reverseEncryption;
};



/*
   Helper macros for creating temporary buffers with an optimization that
   below a given size (OptimizedSize) is allocated on the stack, and when a
   larger size is requested it is allocated on the heap.

   BUFFER_RESET should be called for the same name as BUFFER_INIT
 */
#define BUFFER_INIT( Name, OptimizedSize, Size ) \
  char Name ## _Raw [ OptimizedSize ]; \
  char *Name = Name ## _Raw; \
  if( sizeof(Name ## _Raw) < Size ) { \
    Name = new char[ Size ];\
  } \
  memset( Name, 0, Size )

#define BUFFER_RESET( Name ) \
  do { \
    if( Name != Name ## _Raw ) { \
      delete[] Name; \
      Name = Name ## _Raw; \
    } \
  } while(0)

}  // namespace encfs

#endif