Shuffle the modules about a bit.

1 files changed, 446 insertions, 0 deletions

diff --git a/modules/codepage.cpp b/modules/codepage.cpp
new file mode 100644
index 000000000..fe6aafad1
--- /dev/null
+++ b/modules/codepage.cpp
@@ -0,0 +1,446 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2020-2023 Sadie Powell <sadie@witchery.services>
+ *
+ * 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/>.
+ */
+
+
+#include "inspircd.h"
+#include "modules/isupport.h"
+
+class Codepage
+{
+public:
+	enum class AllowCharacterResult
+		: uint8_t
+	{
+		// The character is allowed in a nick.
+		OKAY,
+
+		// The character is never valid in a nick.
+		NOT_VALID,
+
+		// The character is not valid at the front of a nick.
+		NOT_VALID_AT_FRONT,
+	};
+
+	// The mapping of lower case characters to upper case characters.
+	unsigned char casemap[UCHAR_MAX + 1];
+
+	// Initialises the Codepage class.
+	Codepage()
+	{
+		for (size_t i = 0; i <= UCHAR_MAX; ++i)
+			casemap[i] = i;
+	}
+
+	// Destroys the Codepage class.
+	virtual ~Codepage() = default;
+
+	// Specifies that a character is allowed.
+	virtual AllowCharacterResult AllowCharacter(uint32_t character, bool front)
+	{
+		if (front)
+		{
+			// Nicknames can not begin with a number as that would collide with
+			// a user identifier.
+			if (character >= '0' && character <= '9')
+				return AllowCharacterResult::NOT_VALID_AT_FRONT;
+
+			// Nicknames can not begin with a : or a $ as they have a special
+			// meaning within the IRC message format.
+			if (character == '$' || character == ':')
+				return AllowCharacterResult::NOT_VALID_AT_FRONT;
+
+			// Nicknames can not begin with a channel prefix character (e.g. #)
+			// as they are used to differentiate users from channels in message
+			// targets.
+			if (ServerInstance->Channels.IsPrefix(character))
+				return AllowCharacterResult::NOT_VALID_AT_FRONT;
+
+			// Nicknames can not begin with a prefix mode character (e.g. @)
+			// as they are used as a nick prefix when sending a STATUSMSG.
+			if (ServerInstance->Modes.FindPrefix(character))
+				return AllowCharacterResult::NOT_VALID_AT_FRONT;
+		}
+
+		// Nicknames can never contain NUL, CR, LF, SPACE, COMMA, PERIOD,
+		// ASTERISK, QUESTION MARK, EXCLAMATION MARK, or AT SIGN as they are
+		// either banned within an IRC message or have special meaning within
+		// the IRC message format.
+		switch (character)
+		{
+			case '\0':
+			case '\n':
+			case '\r':
+			case ' ':
+			case '!':
+			case '*':
+			case ',':
+			case '.':
+			case '?':
+			case '@':
+				return AllowCharacterResult::NOT_VALID;
+		}
+
+
+		// The character is probably okay?
+		return AllowCharacterResult::OKAY;
+	}
+
+	// Determines whether a nickname is valid.
+	virtual bool IsValidNick(const std::string_view& nick) = 0;
+
+	// Retrieves the link data for this codepage.
+	virtual void GetLinkData(Module::LinkData& data, std::string& compatdata) const = 0;
+
+	// Maps an upper case character to a lower case character.
+	virtual bool Map(uint32_t upper, uint32_t lower) = 0;
+};
+
+class SingleByteCodepage final
+	: public Codepage
+{
+private:
+	// The characters which are allowed in nicknames.
+	CharState allowedchars;
+
+	// The characters which are allowed at the front of a nickname.
+	CharState allowedfrontchars;
+
+public:
+	AllowCharacterResult AllowCharacter(uint32_t character, bool front) override
+	{
+		// Single byte codepage can, as their name suggests, only be one byte in size.
+		if (character > UCHAR_MAX)
+			return AllowCharacterResult::NOT_VALID;
+
+		// Check the common allowed character rules.
+		AllowCharacterResult result = Codepage::AllowCharacter(character, front);
+		if (result != AllowCharacterResult::OKAY)
+			return result;
+
+		// The character is okay.
+		allowedchars.set(character);
+		allowedfrontchars.set(character, front);
+		return AllowCharacterResult::OKAY;
+	}
+
+	bool IsValidNick(const std::string_view& nick) override
+	{
+		if (nick.empty() || nick.length() > ServerInstance->Config->Limits.MaxNick)
+			return false;
+
+		for (std::string_view::const_iterator iter = nick.begin(); iter != nick.end(); ++iter)
+		{
+			unsigned char chr = static_cast<unsigned char>(*iter);
+
+			// Check that the character is allowed at the front of the nick.
+			if (iter == nick.begin() && !allowedfrontchars[chr])
+				return false;
+
+			// Check that the character is allowed in the nick.
+			if (!allowedchars[chr])
+				return false;
+		}
+
+		return true;
+	}
+
+	void GetLinkData(Module::LinkData& data, std::string& compatdata) const override
+	{
+		for (size_t i = 0; i < allowedfrontchars.size(); ++i)
+			if (allowedfrontchars[i])
+				data["front"].push_back(static_cast<unsigned char>(i));
+
+		for (size_t i = 0; i < allowedchars.size(); ++i)
+			if (allowedchars[i])
+				data["middle"].push_back(static_cast<unsigned char>(i));
+
+		for (size_t i = 0; i < sizeof(casemap); ++i)
+		{
+			if (casemap[i] == i)
+				continue;
+
+			data["map"].push_back(static_cast<unsigned char>(i));
+			data["map"].push_back(casemap[i]);
+			data["map"].push_back(',');
+		}
+
+		compatdata = fmt::format("front={}&middle={}&map={}", data["front"], data["middle"], data["map"]);
+	}
+
+	bool Map(uint32_t upper, uint32_t lower) override
+	{
+		if (upper > UCHAR_MAX || lower > UCHAR_MAX)
+			return false;
+
+		casemap[upper] = lower;
+		return true;
+	}
+};
+
+class ModuleCodepage final
+	: public Module
+	, public ISupport::EventListener
+{
+private:
+	// The currently active codepage.
+	std::unique_ptr<Codepage> codepage = nullptr;
+
+	// The character map which was set before this module was loaded.
+	const unsigned char* origcasemap;
+
+	// The name of the character map which was set before this module was loaded.
+	const std::string origcasemapname;
+
+	// The IsNick handler which was set before this module was loaded.
+	const std::function<bool(const std::string_view&)> origisnick;
+
+	// The character set used for the codepage.
+	std::string charset;
+
+	template <typename T>
+	static void RehashHashmap(T& hashmap)
+	{
+		T newhash(hashmap.bucket_count());
+		for (const auto& [key, value] : hashmap)
+			newhash.emplace(key, value);
+		hashmap.swap(newhash);
+	}
+
+	static void DestroyChannel(Channel* chan)
+	{
+		// Remove all of the users from the channel. Using KICK here will mean
+		// the user's client will probably attempt to rejoin and will enter the
+		// succeeding channel. Unfortunately this is the best we can do for now.
+		while (!chan->userlist.empty())
+			chan->KickUser(ServerInstance->FakeClient, chan->userlist.begin(), "This channel does not exist anymore.");
+
+		// Remove all modes from the channel just in case one of them keeps the channel open.
+		Modes::ChangeList changelist;
+		for (const auto& [_, mh] : ServerInstance->Modes.GetModes(MODETYPE_CHANNEL))
+			mh->RemoveMode(chan, changelist);
+		ServerInstance->Modes.Process(ServerInstance->FakeClient, chan, nullptr, changelist, ModeParser::MODE_LOCALONLY);
+
+		// The channel will be destroyed automatically by CheckDestroy.
+	}
+
+	static void ChangeNick(User* user, const std::string& message)
+	{
+		user->WriteNumeric(RPL_SAVENICK, user->uuid, message);
+		user->ChangeNick(user->uuid);
+	}
+
+	static void CheckDuplicateChan()
+	{
+		ChannelMap duplicates;
+		for (auto &[_, chan] : ServerInstance->Channels.GetChans())
+		{
+			auto check = duplicates.insert(std::make_pair(chan->name, chan));
+			if (check.second)
+				continue; // No duplicate.
+
+			Channel* otherchan = check.first->second;
+			if (otherchan->age < chan->age)
+			{
+				// The other channel was created first.
+				DestroyChannel(chan);
+			}
+			else if (otherchan->age > chan->age)
+			{
+				// The other channel was created last.
+				DestroyChannel(otherchan);
+				check.first->second = chan;
+			}
+			else
+			{
+				// Both created at the same time.
+				DestroyChannel(chan);
+				DestroyChannel(otherchan);
+				duplicates.erase(check.first);
+			}
+		}
+	}
+
+	static void CheckDuplicateNick()
+	{
+		UserMap duplicates;
+		for (auto* user : ServerInstance->Users.GetLocalUsers())
+		{
+			if (user->nick == user->uuid)
+				continue; // UUID users are always unique.
+
+			auto check = duplicates.insert(std::make_pair(user->nick, user));
+			if (check.second)
+				continue; // No duplicate.
+
+			User* otheruser = check.first->second;
+			if (otheruser->nickchanged < user->nickchanged)
+			{
+				// The other user connected first.
+				ChangeNick(user, "Your nickname is no longer available.");
+			}
+			else if (otheruser->nickchanged > user->nickchanged)
+			{
+				// The other user connected last.
+				ChangeNick(otheruser, "Your nickname is no longer available.");
+				check.first->second = user;
+			}
+			else
+			{
+				// Both connected at the same time.
+				ChangeNick(user, "Your nickname is no longer available.");
+				ChangeNick(otheruser, "Your nickname is no longer available.");
+				duplicates.erase(check.first);
+			}
+		}
+	}
+
+	static void CheckInvalidNick()
+	{
+		for (auto* user : ServerInstance->Users.GetLocalUsers())
+		{
+			if (user->nick != user->uuid && !ServerInstance->IsNick(user->nick))
+				ChangeNick(user, "Your nickname is no longer valid.");
+		}
+	}
+
+	static void CheckRehash(unsigned char* prevmap)
+	{
+		if (!memcmp(prevmap, national_case_insensitive_map, UCHAR_MAX))
+			return;
+
+		RehashHashmap(ServerInstance->Users.clientlist);
+		RehashHashmap(ServerInstance->Users.uuidlist);
+		RehashHashmap(ServerInstance->Channels.GetChans());
+	}
+
+	static std::string GetPrintable(uint32_t chr)
+	{
+		if (isprint(chr))
+			return fmt::format("{} ({})", reinterpret_cast<const char*>(&chr), chr);
+		else
+			return fmt::format("{}", chr);
+	}
+
+public:
+	ModuleCodepage()
+		: Module(VF_VENDOR | VF_COMMON, "Allows the server administrator to define what characters are allowed in nicknames and how characters should be compared in a case insensitive way.")
+		, ISupport::EventListener(this)
+		, origcasemap(national_case_insensitive_map)
+		, origcasemapname(ServerInstance->Config->CaseMapping)
+		, origisnick(ServerInstance->IsNick)
+	{
+	}
+
+	~ModuleCodepage() override
+	{
+		ServerInstance->IsNick = origisnick;
+		CheckInvalidNick();
+
+		ServerInstance->Config->CaseMapping = origcasemapname;
+		national_case_insensitive_map = origcasemap;
+		CheckDuplicateChan();
+		CheckDuplicateNick();
+		if (codepage) // nullptr if ReadConfig throws on load.
+			CheckRehash(codepage->casemap);
+	}
+
+	void ReadConfig(ConfigStatus& status) override
+	{
+		const auto& codepagetag = ServerInstance->Config->ConfValue("codepage");
+
+		const std::string name = codepagetag->getString("name");
+		if (name.empty())
+			throw ModuleException(this, "<codepage:name> is a required field!");
+
+		std::unique_ptr<Codepage> newcodepage = std::make_unique<SingleByteCodepage>();
+		for (const auto& [_, tag] : ServerInstance->Config->ConfTags("cpchars"))
+		{
+			uint32_t begin = tag->getNum<uint32_t>("begin", tag->getNum<uint32_t>("index", 0));
+			if (!begin)
+				throw ModuleException(this, "<cpchars> tag without index or begin specified at " + tag->source.str());
+
+			uint32_t end = tag->getNum<uint32_t>("end", begin);
+			if (begin > end)
+				throw ModuleException(this, "<cpchars:begin> must be lower than <cpchars:end> at " + tag->source.str());
+
+			bool front = tag->getBool("front", false);
+			for (uint32_t pos = begin; pos <= end; ++pos)
+			{
+				switch (newcodepage->AllowCharacter(pos, front))
+				{
+					case Codepage::AllowCharacterResult::OKAY:
+						ServerInstance->Logs.Debug(MODNAME, "Marked {} as allowed (front: {})",
+							GetPrintable(pos), front ? "yes" : "no");
+						break;
+
+					case Codepage::AllowCharacterResult::NOT_VALID:
+						throw ModuleException(this, fmt::format("<cpchars> tag contains a forbidden character: {} at {}",
+							GetPrintable(pos), tag->source.str()));
+
+					case Codepage::AllowCharacterResult::NOT_VALID_AT_FRONT:
+						throw ModuleException(this, fmt::format("<cpchars> tag contains a forbidden front character: {} at {}",
+							GetPrintable(pos), tag->source.str()));
+				}
+			}
+		}
+
+		for (const auto& [_, tag] : ServerInstance->Config->ConfTags("cpcase"))
+		{
+			uint32_t lower = tag->getNum<uint32_t>("lower", 0);
+			if (!lower)
+				throw ModuleException(this, "<cpcase:lower> is required at " + tag->source.str());
+
+			uint32_t upper = tag->getNum<uint32_t>("upper", 0);
+			if (!upper)
+				throw ModuleException(this, "<cpcase:upper> is required at " + tag->source.str());
+
+			if (!newcodepage->Map(upper, lower))
+				throw ModuleException(this, "Malformed <cpcase> tag at " + tag->source.str());
+
+			ServerInstance->Logs.Debug(MODNAME, "Marked {} as the lower case version of {}",
+				GetPrintable(lower), GetPrintable(upper));
+		}
+
+		charset = codepagetag->getString("charset");
+		std::swap(codepage, newcodepage);
+		ServerInstance->IsNick = [this](const std::string_view& nick) { return codepage->IsValidNick(nick); };
+		CheckInvalidNick();
+
+		ServerInstance->Config->CaseMapping = name;
+		national_case_insensitive_map = codepage->casemap;
+		if (newcodepage) // nullptr on first read.
+		{
+			CheckDuplicateChan();
+			CheckDuplicateNick();
+			CheckRehash(newcodepage->casemap);
+		}
+	}
+
+	void OnBuildISupport(ISupport::TokenMap& tokens) override
+	{
+		if (!charset.empty())
+			tokens["CHARSET"] = charset;
+	}
+
+	void GetLinkData(LinkData& data, std::string& compatdata) override
+	{
+		codepage->GetLinkData(data, compatdata);
+	}
+};
+
+MODULE_INIT(ModuleCodepage)