// Copyright (C) 1999-2005 Open Source Telecom Corporation.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
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//
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// file does not by itself cause the resulting executable to be covered by
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/**
 * @file digest.h
 * @short Digest algorithms: checksum, CRC and MD5.
 **/

#ifndef	CCXX_DIGEST_H_
#define	CCXX_DIGEST_H_

#ifndef CCXX_MISSING_H_
#include <cc++/missing.h>
#endif

#ifndef CCXX_THREAD_H_
#include <cc++/thread.h>
#endif

#ifndef	CCXX_EXCEPTION_H_
#include <cc++/exception.h>
#endif

#ifdef	CCXX_NAMESPACES
namespace ost {
#endif

/**
 * The digest base class is used for implementing and deriving one way
 * hashing functions.
 *
 * @author David Sugar <dyfet@ostel.com>
 * @short base class for hashing services.
 */
class __EXPORT Digest : protected std::streambuf, public std::ostream
{
protected:
	Digest();

	/**
	 * Get the size of a digest in octets.
	 *
	 * @return number of bytes in digest.
	 */
	virtual unsigned getSize(void) = 0;

	/**
	 * Copy the binary digest buffer to user memory.
	 *
	 * @return number of bytes in digest.
	 * @param buffer to write into.
	 */
	virtual unsigned getDigest(unsigned char *buffer) = 0;

	/**
	 * Put data into the digest bypassing the stream subsystem.
	 *
	 * @param buffer to read from.
	 * @param length of data.
	 */
	virtual void putDigest(const unsigned char *buffer, unsigned length) = 0;

	/**
	 * print a digest string for export.
	 *
	 * @return string representation of digest.
	 */
	virtual std::ostream &strDigest(std::ostream &os) = 0;

	friend std::ostream &operator<<(std::ostream &os, Digest &ia)
		{return ia.strDigest(os);};

public:
	/**
	 * Reset the digest table to an initial default value.
	 */
	virtual void initDigest(void) = 0;

	virtual ~Digest();
};

/**
 * A simple checksum digest function.
 *
 * @author David Sugar <dyfet@ostel.com>
 * @short checksum hash function.
 */
class __EXPORT ChecksumDigest : public Digest
{
private:
	unsigned char csum;

protected:
	int overflow(int c);
	std::ostream &strDigest(std::ostream &os);

public:
	ChecksumDigest();

	void initDigest(void)
		{csum = 0;};

	unsigned getSize(void)
		{return 1;};

	unsigned getDigest(unsigned char *buffer);

	void putDigest(const unsigned char *buffer, unsigned length);
};

/**
 * A crc16 collection/compution hash accumulator class.
 *
 * @author David Sugar <dyfet@ostel.com>
 * @short crc16 computation hash.
 */
class __EXPORT CRC16Digest : public Digest
{
private:
	unsigned short crc16;

protected:
	int overflow(int c);

	std::ostream &strDigest(std::ostream &os);

public:
	CRC16Digest();

	inline void initDigest(void)
		{crc16 = 0;};

	inline unsigned getSize(void)
		{return 2;};

	unsigned getDigest(unsigned char *buffer);

	void putDigest(const unsigned char *buffer, unsigned length);
};

/**
 * A crc32 collection/computation hash accumulator class.
 *
 * @author Kevin Kraatz <kraatz@arlut.utexas.edu>
 * @short crc32 computation hash.
 */

class __EXPORT CRC32Digest : public Digest
{
private:
   unsigned long crc_table[256];
   unsigned long crc_reg;
   unsigned long crc32;

protected:
   unsigned char overflow(unsigned char octet);

   std::ostream &strDigest(std::ostream &os);

public:
   CRC32Digest();

   void initDigest(void);

   inline unsigned getSize(void) {return 4;}

   unsigned getDigest(unsigned char *buffer);

   void putDigest(const unsigned char *buffer, unsigned length);
};

/**
 * A md5 collection/computation accululator class.
 *
 * @author David Sugar <dyfet@ostel.com>
 * @short md5 hash accumulation.
 */
class __EXPORT MD5Digest : public Digest
{
private:
	unsigned long state[4];
	unsigned long count[2];
	unsigned char buf[64];
	unsigned bpos;
	unsigned char md5[16];
	bool updated;

protected:
	int overflow(int c);

	void update(void);

	void commit(void);

	std::ostream &strDigest(std::ostream &os);

public:
	MD5Digest();

	void initDigest(void);

	inline unsigned getSize(void)
		{return 16;};

	unsigned getDigest(unsigned char *buffer);

	void putDigest(const unsigned char *buffer, unsigned len);
};

#ifdef	COMMON_STD_EXCEPTION
/**
 * DigestException
 *
 * Exception classes that pertain to errors when making or otherwise
 * working with digests.
 *
 * @author Elizabeth Barham <lizzy@soggytrousers.net>
 * @short Exceptions involving digests.
 */
class __EXPORT DigestException : public Exception {
public:
	DigestException(const String &str) : Exception(str) {};
};
#endif

#ifdef	CCXX_NAMESPACES
}
#endif

#endif
/** EMACS **
 * Local variables:
 * mode: c++
 * c-basic-offset: 8
 * End:
 */

