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#ifndef FUZZY_H
#define FUZZY_H
/*
* Copyright (C) ManTech International Corporation 2010
* Copyright (C) Kyrus 2012
* Copyright (C) 2013 Helmut Grohne <helmut@subdivi.de>
*
* $Id$
*
* 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
* (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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Earlier versions of this code can be found at:
* http://ssdeep.sf.net/
*/
/// \mainpage
/// This is the documentation for the fuzzy hashing API from ssdeep.
///
/// There is a complete function reference in fuzzy.h.
///
/// The most recent version of this documentation can be found
/// at http://ssdeep.sourceforge.net/.
///
/// \copydoc fuzzy.h
///
/// \version 3.0
///
/// \author Jesse Kornblum, research@jessekornblum.com
/// \author Helmut Grohne, helmut@subdivi.de
/// \file fuzzy.h
/// \brief
/// These functions allow a programmer to compute the fuzzy hashes
/// (also called the context-triggered piecewise hashes) of
/// \link fuzzy_hash_buf() a buffer
/// of text @endlink,
/// \link fuzzy_hash_filename() the contents of a file on the disk @endlink,
/// and
/// @link fuzzy_hash_file() the contents of
/// an open file handle @endlink .
/// There is also a function to
/// @link fuzzy_compare() compute the
/// similarity between any two fuzzy signatures @endlink.
#include <stdint.h>
#include <stdio.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief fuzzy_digest flag indicating to eliminate sequences of more than
* three identical characters
*/
#define FUZZY_FLAG_ELIMSEQ 0x1u
/**
* @brief fuzzy_digest flag indicating not to truncate the second part to
* SPAMSUM_LENGTH/2 characters.
*/
#define FUZZY_FLAG_NOTRUNC 0x2u
struct fuzzy_state;
/**
* @brief Construct a fuzzy_state object and return it.
*
* To use it call fuzzy_update and fuzzy_digest on it. It must be disposed
* with fuzzy_free.
* @return the constructed fuzzy_state or NULL on failure
*/
extern /*@only@*/ /*@null@*/ struct fuzzy_state *fuzzy_new(void);
/**
* @brief Create a copy of a fuzzy_state object and return it.
*
* It can be used with fuzzy_update and fuzzy_digest independently of
* the original. It must be disposed with fuzzy_free like the original
* has to be cleared in this way.
* @param state The fuzzy state
* @return the cloned fuzzy_state or NULL on failure
*/
extern /*@only@*/ /*@null@*/ struct fuzzy_state *fuzzy_clone(const struct fuzzy_state *state);
/**
* @brief Set fixed length of input
*
* If we know the file size to compute fuzzy digest, we can boost
* computation by restricting range of blocksize.
* @param state The fuzzy state
* @param total_fixed_length Total length of the data to generate digest
* @return 0 on success or -1 on failure
*/
extern int fuzzy_set_total_input_length(struct fuzzy_state *state, uint_least64_t total_fixed_length);
/**
* @brief Feed the data contained in the given buffer to the state.
*
* When an error occurs, the state is undefined. In that case it must not be
* passed to any function besides fuzzy_free.
* @param state The fuzzy state
* @param buffer The data to be hashes
* @param buffer_size The length of the given buffer
* @return zero on success, non-zero on error
*/
extern int fuzzy_update(struct fuzzy_state *state,
const unsigned char *buffer,
size_t buffer_size);
/**
* @brief Obtain the fuzzy hash from the state.
*
* This operation does not change the state at all. It reports the hash for the
* concatenation of the data previously fed using fuzzy_update.
* @param state The fuzzy state
* @param result Where the fuzzy hash is stored. This variable
* must be allocated to hold at least FUZZY_MAX_RESULT bytes.
* @param flags is a bitwise or of FUZZY_FLAG_* macros. The absence of flags is
* represented by a zero.
* @return zero on success, non-zero on error
*/
extern int fuzzy_digest(const struct fuzzy_state *state,
/*@out@*/ char *result,
unsigned int flags);
/**
* @brief Dispose a fuzzy state.
* @param state The fuzzy state to dispose
*/
extern void fuzzy_free(/*@only@*/ struct fuzzy_state *state);
/**
* @brief Compute the fuzzy hash of a buffer
*
* The computes the fuzzy hash of the first buf_len bytes of the buffer.
* It is the caller's responsibility to append the filename,
* if any, to result after computation.
* @param buf The data to be fuzzy hashed
* @param buf_len The length of the data being hashed
* @param result Where the fuzzy hash of buf is stored. This variable
* must be allocated to hold at least FUZZY_MAX_RESULT bytes.
* @return Returns zero on success, non-zero on error.
*/
extern int fuzzy_hash_buf(const unsigned char *buf,
uint32_t buf_len,
/*@out@*/ char *result);
/**
* @brief Compute the fuzzy hash of a file using an open handle
*
* Computes the fuzzy hash of the contents of the open file, starting
* at the beginning of the file. When finished, the file pointer is
* returned to its original position. If an error occurs, the file
* pointer's value is undefined.
* It is the callers's responsibility to append the filename
* to the result after computation.
* @param handle Open handle to the file to be hashed
* @param result Where the fuzzy hash of the file is stored. This
* variable must be allocated to hold at least FUZZY_MAX_RESULT bytes.
* @return Returns zero on success, non-zero on error
*/
extern int fuzzy_hash_file(FILE *handle, /*@out@*/ char *result);
/**
* @brief Compute the fuzzy hash of a stream using an open handle
*
* Computes the fuzzy hash of the contents of the open stream, starting at the
* current file position until reaching EOF. Unlike fuzzy_hash_file the stream
* is never seeked. If an error occurs, the result as well as the file position
* are undefined.
* It is the callers's responsibility to append the filename
* to the result after computation.
* @param handle Open handle to the stream to be hashed
* @param result Where the fuzzy hash of the file is stored. This
* variable must be allocated to hold at least FUZZY_MAX_RESULT bytes.
* @return Returns zero on success, non-zero on error
*/
extern int fuzzy_hash_stream(FILE *handle, /*@out@*/ char *result);
/**
* @brief Compute the fuzzy hash of a file
*
* Opens, reads, and hashes the contents of the file 'filename'
* The result must be allocated to hold FUZZY_MAX_RESULT characters.
* It is the caller's responsibility to append the filename
* to the result after computation.
* @param filename The file to be hashed
* @param result Where the fuzzy hash of the file is stored. This
* variable must be allocated to hold at least FUZZY_MAX_RESULT bytes.
* @return Returns zero on success, non-zero on error.
*/
extern int fuzzy_hash_filename(const char *filename, /*@out@*/ char * result);
/// Computes the match score between two fuzzy hash signatures.
/// @return Returns a value from zero to 100 indicating the
/// match score of the
/// two signatures. A match score of zero indicates the signatures
/// did not match. When an error occurs, such as if one of the
/// inputs is NULL, returns -1.
extern int fuzzy_compare(const char *sig1, const char *sig2);
/** Length of an individual fuzzy hash signature component. */
#define SPAMSUM_LENGTH 64
/** The longest possible length for a fuzzy hash signature
* (without the filename) */
#define FUZZY_MAX_RESULT (2 * SPAMSUM_LENGTH + 20)
#ifdef __cplusplus
}
#endif
#endif