zeek/src/RE.h

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

#pragma once

#include <sys/types.h> // for u_char
#include <ctype.h>
#include <set>
#include <map>
#include <string>

#include "zeek/List.h"
#include "zeek/CCL.h"
#include "zeek/EquivClass.h"

typedef int (*cce_func)(int);

// This method is automatically generated by flex and shouldn't be namespaced
extern int re_lex(void);

namespace zeek {

class String;
class RE_Matcher;

namespace detail {

class NFA_Machine;
class DFA_Machine;
class DFA_State;
class Specific_RE_Matcher;
class CCL;

extern int case_insensitive;
extern CCL* curr_ccl;
extern NFA_Machine* nfa;
extern Specific_RE_Matcher* rem;
extern const char* RE_parse_input;

extern int clower(int);
extern void synerr(const char str[]);

using AcceptIdx = int;
using AcceptingSet = std::set<AcceptIdx>;
using MatchPos = uint64_t;
using AcceptingMatchSet = std::map<AcceptIdx, MatchPos>;
using string_list = name_list;

enum match_type { MATCH_ANYWHERE, MATCH_EXACTLY };

// A "specific" RE matcher will match one type of pattern: either
// MATCH_ANYWHERE or MATCH_EXACTLY.

class Specific_RE_Matcher {
public:
	explicit Specific_RE_Matcher(match_type mt, int multiline=0);
	~Specific_RE_Matcher();

	void AddPat(const char* pat);

	void MakeCaseInsensitive();

	void SetPat(const char* pat)	{ pattern_text = util::copy_string(pat); }

	bool Compile(bool lazy = false);

	// The following is vestigial from flex's use of "{name}" definitions.
	// It's here because at some point we may want to support such
	// functionality.
	std::string LookupDef(const std::string& def);

	void InsertCCL(const char* txt, CCL* ccl) { ccl_dict[std::string(txt)] = ccl; }
	int InsertCCL(CCL* ccl)
		{
		ccl_list.push_back(ccl);
		return ccl_list.length() - 1;
		}
	CCL* LookupCCL(const char* txt)
		{
		const auto& iter = ccl_dict.find(std::string(txt));
		if ( iter != ccl_dict.end() )
			return iter->second;

		return nullptr;
		}
	CCL* LookupCCL(int index)	{ return ccl_list[index]; }
	CCL* AnyCCL();

	void ConvertCCLs();

	bool MatchAll(const char* s);
	bool MatchAll(const String* s);

	// Compiles a set of regular expressions simultaniously.
	// 'idx' contains indizes associated with the expressions.
	// On matching, the set of indizes is returned which correspond
	// to the matching expressions.  (idx must not contain zeros).
	bool CompileSet(const string_list& set, const int_list& idx);

	// Returns the position in s just beyond where the first match
	// occurs, or 0 if there is no such position in s.  Note that
	// if the pattern matches empty strings, matching continues
	// in an attempt to match at least one character.
	int Match(const char* s);
	int Match(const String* s);

	int LongestMatch(const char* s);
	int LongestMatch(const String* s);
	int LongestMatch(const u_char* bv, int n);

	EquivClass* EC()		{ return &equiv_class; }

	const char* PatternText() const	{ return pattern_text; }

	DFA_Machine* DFA() const		{ return dfa; }

	void Dump(FILE* f);

	unsigned int MemoryAllocation() const;

protected:
	void AddAnywherePat(const char* pat);
	void AddExactPat(const char* pat);

	// Used by the above.  orig_fmt is the format to use when building
	// up a new pattern_text from the given pattern; app_fmt is for when
	// appending to an existing pattern_text.
	void AddPat(const char* pat, const char* orig_fmt, const char* app_fmt);

	bool MatchAll(const u_char* bv, int n);
	int Match(const u_char* bv, int n);

	match_type mt;
	int multiline;
	char* pattern_text;

	std::map<std::string, std::string> defs;
	std::map<std::string, CCL*> ccl_dict;
	PList<CCL> ccl_list;
	EquivClass equiv_class;
	int* ecs;
	DFA_Machine* dfa;
	CCL* any_ccl;
	AcceptingSet* accepted;
};

class RE_Match_State {
public:
	explicit RE_Match_State(Specific_RE_Matcher* matcher)
		{
		dfa = matcher->DFA() ? matcher->DFA() : nullptr;
		ecs = matcher->EC()->EquivClasses();
		current_pos = -1;
		current_state = nullptr;
		}

	const AcceptingMatchSet& AcceptedMatches() const
		{ return accepted_matches; }

	// Returns the number of bytes feeded into the matcher so far
	int Length()	{ return current_pos; }

	// Returns true if this inputs leads to at least one new match.
	// If clear is true, starts matching over.
	bool Match(const u_char* bv, int n, bool bol, bool eol, bool clear);

	void Clear()
		{
		current_pos = -1;
		current_state = nullptr;
		accepted_matches.clear();
		}

	void AddMatches(const AcceptingSet& as, MatchPos position);

protected:
	DFA_Machine* dfa;
	int* ecs;

	AcceptingMatchSet accepted_matches;
	DFA_State* current_state;
	int current_pos;
};

extern RE_Matcher* RE_Matcher_conjunction(const RE_Matcher* re1, const RE_Matcher* re2);
extern RE_Matcher* RE_Matcher_disjunction(const RE_Matcher* re1, const RE_Matcher* re2);

} // namespace detail

class RE_Matcher final {
public:
	RE_Matcher();
	explicit RE_Matcher(const char* pat);
	RE_Matcher(const char* exact_pat, const char* anywhere_pat);
	~RE_Matcher();

	void AddPat(const char* pat);

	// Makes the matcher as specified to date case-insensitive.
	void MakeCaseInsensitive();

	bool Compile(bool lazy = false);

	// Returns true if s exactly matches the pattern, false otherwise.
	bool MatchExactly(const char* s)
		{ return re_exact->MatchAll(s); }
	bool MatchExactly(const String* s)
		{ return re_exact->MatchAll(s); }

	// Returns the position in s just beyond where the first match
	// occurs, or 0 if there is no such position in s.  Note that
	// if the pattern matches empty strings, matching continues
	// in an attempt to match at least one character.
	int MatchAnywhere(const char* s)
		{ return re_anywhere->Match(s); }
	int MatchAnywhere(const String* s)
		{ return re_anywhere->Match(s); }

	// Note: it matches the *longest* prefix and returns the
	// length of matched prefix. It returns -1 on mismatch.
	int MatchPrefix(const char* s)
		{ return re_exact->LongestMatch(s); }
	int MatchPrefix(const String* s)
		{ return re_exact->LongestMatch(s); }
	int MatchPrefix(const u_char* s, int n)
		{ return re_exact->LongestMatch(s, n); }

	const char* PatternText() const	{ return re_exact->PatternText(); }
	const char* AnywherePatternText() const	{ return re_anywhere->PatternText(); }

	unsigned int MemoryAllocation() const
		{
		return padded_sizeof(*this)
			+ (re_anywhere ? re_anywhere->MemoryAllocation() : 0)
			+ (re_exact ? re_exact->MemoryAllocation() : 0);
		}

protected:
	detail::Specific_RE_Matcher* re_anywhere;
	detail::Specific_RE_Matcher* re_exact;
};

} // namespace zeek