inspircd/include/hashcomp.h

/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2013, 2018-2022 Sadie Powell <sadie@witchery.services>
 *   Copyright (C) 2013 Adam <Adam@anope.org>
 *   Copyright (C) 2012-2013, 2016 Attila Molnar <attilamolnar@hush.com>
 *   Copyright (C) 2012 Robby <robby@chatbelgie.be>
 *   Copyright (C) 2009 Daniel De Graaf <danieldg@inspircd.org>
 *   Copyright (C) 2008-2009 Robin Burchell <robin+git@viroteck.net>
 *   Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
 *   Copyright (C) 2005-2008 Craig Edwards <brain@inspircd.org>
 *
 * This file is part of InspIRCd.  InspIRCd 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, version 2.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */


#pragma once

#include "inspircd.h"
#include "convto.h"

/*******************************************************
 * This file contains classes and templates that deal
 * with the comparison and hashing of 'irc strings'.
 * An 'irc string' is a string which compares in a
 * case insensitive manner, and as per RFC 1459 will
 * treat [ identical to {, ] identical to }, and \
 * as identical to |.
 *
 * There are functors that accept std::string and
 * compare/hash them as type irc::string by using
 * mapping arrays internally.
 *******************************************************/

/** Separate from the other casemap tables so that code *can* still exclusively rely on RFC casemapping
 * if it must.
 *
 * This is provided as a pointer so that modules can change it to their custom mapping tables,
 * e.g. for national character support.
 */
CoreExport extern const unsigned char* national_case_insensitive_map;

/** Case insensitive map, ASCII rules.
 * That is;
 * [ != {, but A == a.
 */
CoreExport extern const unsigned char ascii_case_insensitive_map[256];

/** The irc namespace contains a number of helper classes.
 */
namespace irc
{
	/** Check if two IRC object (e.g. nick or channel) names are equal.
	 * This function uses national_case_insensitive_map to determine equality, which, by default does comparison
	 * according to RFC 1459, treating certain otherwise non-identical characters as identical.
	 * @param s1 First string to compare
	 * @param s2 Second string to compare
	 * @return True if the two names are equal, false otherwise
	 */
	CoreExport bool equals(const std::string_view& s1, const std::string_view& s2);

	/** Check whether \p needle exists within \p haystack.
	 * @param haystack The string to search within.
	 * @param needle The string to search for.
	 * @return Either the index at which \p needle was found or std::string::npos.
	 */
	CoreExport size_t find(const std::string_view& haystack, const std::string_view& needle);

	/** This class returns true if two strings match.
	 * Case sensitivity is ignored, and the RFC 'character set'
	 * is adhered to
	 */
	struct StrHashComp final
	{
		/** The operator () does the actual comparison in hash_map
		 */
		bool operator()(const std::string& s1, const std::string& s2) const
		{
			return equals(s1, s2);
		}
	};

	struct insensitive final
	{
		size_t CoreExport operator()(const std::string& s) const;
	};

	struct insensitive_swo
	{
		bool CoreExport operator()(const std::string& a, const std::string& b) const;
	};

	/** irc::sepstream allows for splitting token separated lists.
	 * Each successive call to sepstream::GetToken() returns
	 * the next token, until none remain, at which point the method returns
	 * false.
	 */
	class CoreExport sepstream
	{
	protected:
		/** Original string.
		 */
		std::string tokens;
		/** Separator value
		 */
		char sep;
		/** Current string position
		 */
		size_t pos = 0;
		/** If set then GetToken() can return an empty string
		 */
		bool allow_empty;
	public:
		/** Create a sepstream and fill it with the provided data
		 */
		sepstream(const std::string& source, char separator, bool allowempty = false);

		/** Fetch the next token from the stream
		 * @param token The next token from the stream is placed here
		 * @return True if tokens still remain, false if there are none left
		 */
		bool GetToken(std::string& token);

		/** Fetch the next numeric token from the stream
		 * @param token The next token from the stream is placed here
		 * @return True if tokens still remain, false if there are none left
		 */
		template<typename Numeric>
		bool GetNumericToken(Numeric& token)
		{
			std::string str;
			if (!GetToken(str))
				return false;

			token = ConvToNum<Numeric>(str);
			return true;
		}

		/** Fetch the entire remaining stream, without tokenizing
		 * @return The remaining part of the stream
		 */
		std::string GetRemaining();

		/** Returns true if the end of the stream has been reached
		 * @return True if the end of the stream has been reached, otherwise false
		 */
		bool StreamEnd();
	};

	/** A derived form of sepstream, which separates on commas
	 */
	class CoreExport commasepstream : public sepstream
	{
	public:
		/** Initialize with comma separator
		 */
		commasepstream(const std::string& source, bool allowempty = false)
			: sepstream(source, ',', allowempty)
		{
		}
	};

	/** A derived form of sepstream, which separates on spaces
	 */
	class CoreExport spacesepstream : public sepstream
	{
	public:
		/** Initialize with space separator
		 */
		spacesepstream(const std::string& source, bool allowempty = false)
			: sepstream(source, ' ', allowempty)
		{
		}
	};

	/** irc::tokenstream reads a string formatted as per RFC1459 and RFC2812.
	 * It will split the string into 'tokens' each containing one parameter
	 * from the string.
	 * For instance, if it is instantiated with the string:
	 * "PRIVMSG #test :foo bar baz qux"
	 * then each successive call to tokenstream::GetToken() will return
	 * "PRIVMSG", "#test", "foo bar baz qux", "".
	 * Note that if the whole string starts with a colon this is not taken
	 * to mean the string is all one parameter, and the first item in the
	 * list will be ":item". This is to allow for parsing 'source' fields
	 * from data.
	 */
	class CoreExport tokenstream
	{
	private:
		/** The message we are parsing tokens from. */
		std::string message;

		/** The current position within the message. */
		size_t position = 0;

	public:
		/** Create a tokenstream and fill it with the provided data. */
		tokenstream(const std::string& msg, size_t start = 0, size_t end = std::string::npos);

		/** Retrieves the underlying message. */
		std::string& GetMessage() { return message; }

		/** Retrieve the next \<middle> token in the token stream.
		 * @param token The next token available, or an empty string if none remain.
		 * @return True if tokens are left to be read, false if the last token was just retrieved.
		 */
		bool GetMiddle(std::string& token);

		/** Retrieve the next \<trailing> token in the token stream.
		 * @param token The next token available, or an empty string if none remain.
		 * @return True if tokens are left to be read, false if the last token was just retrieved.
		 */
		bool GetTrailing(std::string& token);
	};

	/** The portparser class separates out a port range into integers.
	 * A port range may be specified in the input string in the form
	 * "6660,6661,6662-6669,7020". The end of the stream is indicated by
	 * a return value of 0 from portparser::GetToken(). If you attempt
	 * to specify an illegal range (e.g. one where start >= end, or
	 * start or end < 0) then GetToken() will return the first element
	 * of the pair of numbers.
	 */
	class CoreExport portparser
	{
	private:

		/** Used to split on commas
		 */
		commasepstream sep;

		/** Current position in a range of ports
		 */
		long in_range = 0;

		/** Starting port in a range of ports
		 */
		long range_begin = 0;

		/** Ending port in a range of ports
		 */
		long range_end = 0;

		/** Allow overlapped port ranges
		 */
		bool overlapped;

		/** Used to determine overlapping of ports
		 * without O(n) algorithm being used
		 */
		std::set<long> overlap_set;

		/** Returns true if val overlaps an existing range
		 */
		bool Overlaps(long val);
	public:

		/** Create a portparser and fill it with the provided data
		 * @param source The source text to parse from
		 * @param allow_overlapped Allow overlapped ranges
		 */
		portparser(const std::string& source, bool allow_overlapped = true);

		/** Fetch the next token from the stream
		 * @return The next port number is returned, or 0 if none remain
		 */
		long GetToken();
	};
}