zeek/src/file_analysis/Analyzer.h

// See the file "COPYING" in the main distribution directory for copyright.

#ifndef FILE_ANALYSIS_ANALYZER_H
#define FILE_ANALYSIS_ANALYZER_H

#include "Val.h"
#include "NetVar.h"
#include "Tag.h"

#include "file_analysis/file_analysis.bif.h"

namespace file_analysis {

class File;

typedef uint32 ID;

/**
 * Base class for analyzers that can be attached to file_analysis::File objects.
 */
class Analyzer {
public:

	/**
	 * Destructor.  Nothing special about it. Virtual since we definitely expect
	 * to delete instances of derived classes via pointers to this class.
	 */
	virtual ~Analyzer();

	/**
	 * Initializes the analyzer before input processing starts.
	 */
	virtual void Init()
		{ }

	/**
	 * Finishes the analyzer's operation after all input has been parsed.
	 */
	virtual void Done()
		{ }

	/**
	 * Subclasses may override this metod to receive file data non-sequentially.
	 * @param data points to start of a chunk of file data.
	 * @param len length in bytes of the chunk of data pointed to by \a data.
	 * @param offset the byte offset within full file that data chunk starts.
	 * @return true if the analyzer is still in a valid state to continue
	 *         receiving data/events or false if it's essentially "done".
	 */
	virtual bool DeliverChunk(const u_char* data, uint64 len, uint64 offset)
		{ return true; }

	/**
	 * Subclasses may override this method to receive file sequentially.
	 * @param data points to start of the next chunk of file data.
	 * @param len length in bytes of the chunk of data pointed to by \a data.
	 * @return true if the analyzer is still in a valid state to continue
	 *         receiving data/events or false if it's essentially "done".
	 */
	virtual bool DeliverStream(const u_char* data, uint64 len)
		{ return true; }

	/**
	 * Subclasses may override this method to specifically handle an EOF signal,
	 * which means no more data is going to be incoming and the analyzer
	 * may be deleted/cleaned up soon.
	 * @return true if the analyzer is still in a valid state to continue
	 *         receiving data/events or false if it's essentially "done".
	 */
	virtual bool EndOfFile()
		{ return true; }

	/**
	 * Subclasses may override this method to handle missing data in a file.
	 * @param offset the byte offset within full file at which the missing
	 *        data chunk occurs.
	 * @param len the number of missing bytes.
	 * @return true if the analyzer is still in a valid state to continue
	 *         receiving data/events or false if it's essentially "done".
	 */
	virtual bool Undelivered(uint64 offset, uint64 len)
		{ return true; }

	/**
	 * @return the analyzer type enum value.
	 */
	file_analysis::Tag Tag() const { return tag; }

	/**
	 * Returns the analyzer instance's internal ID. These IDs are unique
	 * across all analyzers instantiated and can thus be used to
	 * indentify a specific instance.
	 */
	ID GetID() const	{ return id; }

	/**
	 * @return the AnalyzerArgs associated with the analyzer.
	 */
	RecordVal* Args() const { return args; }

	/**
	 * @return the file_analysis::File object to which the analyzer is attached.
	 */
	File* GetFile() const { return file; }

	/**
	 * Sets the tag associated with the analyzer's type. Note that this
	 * can be called only right after construction, if the constructor
	 * did not receive a name or tag. The method cannot be used to change
	 * an existing tag.
	 */
	void SetAnalyzerTag(const file_analysis::Tag& tag);

protected:

	/**
	 * Constructor.  Only derived classes are meant to be instantiated.
	 * @param arg_tag the tag definining the analyzer's type.
	 * @param arg_args an \c AnalyzerArgs (script-layer type) value specifiying
	 *        tunable options, if any, related to a particular analyzer type.
	 * @param arg_file the file to which the the analyzer is being attached.
	 */
	Analyzer(file_analysis::Tag arg_tag, RecordVal* arg_args, File* arg_file)
	    : tag(arg_tag),
	      args(arg_args->Ref()->AsRecordVal()),
	      file(arg_file)
		{
		id = ++id_counter;
		}

	/**
	 * Constructor.  Only derived classes are meant to be instantiated.
	 * As this version of the constructor does not receive a name or tag,
	 * SetAnalyzerTag() must be called before the instance can be used.
	 *
	 * @param arg_args an \c AnalyzerArgs (script-layer type) value specifiying
	 *        tunable options, if any, related to a particular analyzer type.
	 * @param arg_file the file to which the the analyzer is being attached.
	 */
	Analyzer(RecordVal* arg_args, File* arg_file)
	    : tag(),
	      args(arg_args->Ref()->AsRecordVal()),
	      file(arg_file)
		{
		id = ++id_counter;
		}

private:

	ID id;	/**< Unique instance ID. */
	file_analysis::Tag tag;	/**< The particular type of the analyzer instance. */
	RecordVal* args;	/**< \c AnalyzerArgs val gives tunable analyzer params. */
	File* file;	/**< The file to which the analyzer is attached. */

	static ID id_counter;
};

} // namespace file_analysis

#endif