Shuffle the modules about a bit.

1 files changed, 425 insertions, 0 deletions

diff --git a/modules/ident.cpp b/modules/ident.cpp
new file mode 100644
index 000000000..a35e5eb30
--- /dev/null
+++ b/modules/ident.cpp
@@ -0,0 +1,425 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2021 Dominic Hamon
+ *   Copyright (C) 2013, 2018-2023 Sadie Powell <sadie@witchery.services>
+ *   Copyright (C) 2012-2013 Robby <robby@chatbelgie.be>
+ *   Copyright (C) 2012, 2014-2015 Attila Molnar <attilamolnar@hush.com>
+ *   Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org>
+ *   Copyright (C) 2008 Robin Burchell <robin+git@viroteck.net>
+ *   Copyright (C) 2007 John Brooks <john@jbrooks.io>
+ *   Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
+ *   Copyright (C) 2007 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/>.
+ */
+
+
+#include "inspircd.h"
+#include "extension.h"
+
+enum
+{
+	// Either the ident lookup has not started yet or the user is fully connected.
+	IDENT_UNKNOWN = 0,
+
+	// Ident lookups are not enabled and a user has been marked as being skipped.
+	IDENT_SKIPPED,
+
+	// Ident lookups are not enabled and a user has been an insecure ident prefix.
+	IDENT_PREFIXED,
+
+	// An ident lookup was done and an ident was found.
+	IDENT_FOUND,
+
+	// An ident lookup was done but no ident was found
+	IDENT_MISSING
+};
+
+/* --------------------------------------------------------------
+ * Note that this is the third incarnation of m_ident. The first
+ * two attempts were pretty crashy, mainly due to the fact we tried
+ * to use InspSocket/BufferedSocket to make them work. This class
+ * is ok for more heavyweight tasks, it does a lot of things behind
+ * the scenes that are not good for ident sockets and it has a huge
+ * memory footprint!
+ *
+ * To fix all the issues that we had in the old ident modules (many
+ * nasty race conditions that would cause segfaults etc) we have
+ * rewritten this module to use a simplified socket object based
+ * directly off EventHandler. As EventHandler only has low level
+ * readability, writability and error events tied directly to the
+ * socket engine, this makes our lives easier as nothing happens to
+ * our ident lookup class that is outside of this module, or out-
+ * side of the control of the class. There are no timers, internal
+ * events, or such, which will cause the socket to be deleted,
+ * queued for deletion, etc. In fact, there's not even any queueing!
+ *
+ * Using this framework we have a much more stable module.
+ *
+ * A few things to note:
+ *
+ *   O  The only place that may *delete* an active or inactive
+ *      ident socket is OnUserDisconnect in the module class.
+ *      Because this is out of scope of the socket class there is
+ *      no possibility that the socket may ever try to delete
+ *      itself.
+ *
+ *   O  Closure of the ident socket with the Close() method will
+ *      not cause removal of the socket from memory or detachment
+ *      from its 'parent' User class. It will only flag it as an
+ *      inactive socket in the socket engine.
+ *
+ *   O  Timeouts are handled in OnCheckReady at the same time as
+ *      checking if the ident socket has a result. This is done
+ *      by checking if the age the of the class (its instantiation
+ *      time) plus the timeout value is greater than the current time.
+ *
+ *  O   The ident socket is able to but should not modify its
+ *      'parent' user directly. Instead the ident socket class sets
+ *      a completion flag and during the next call to OnCheckReady,
+ *      the completion flag will be checked and any result copied to
+ *      that user's class. This again ensures a single point of socket
+ *      deletion for safer, neater code.
+ *
+ *  O   The code in the constructor of the ident socket is taken from
+ *      BufferedSocket but majorly thinned down. It works for both
+ *      IPv4 and IPv6.
+ *
+ *  O   In the event that the ident socket throws a ModuleException,
+ *      nothing is done. This is counted as total and complete
+ *      failure to create a connection.
+ * --------------------------------------------------------------
+ */
+
+class IdentRequestSocket final
+	: public EventHandler
+{
+public:
+	LocalUser* user;			/* User we are attached to */
+	std::string result;		/* Holds the ident string if done */
+	time_t age;
+	bool done;			/* True if lookup is finished */
+
+	IdentRequestSocket(const Module* mod, LocalUser* luser)
+		: user(luser)
+	{
+		age = ServerInstance->Time();
+
+		SetFd(socket(user->server_sa.family(), SOCK_STREAM, 0));
+		if (!HasFd())
+			throw ModuleException(mod, "Could not create socket");
+
+		done = false;
+
+		irc::sockets::sockaddrs bindaddr(user->server_sa);
+		irc::sockets::sockaddrs connaddr(user->client_sa);
+
+		if (connaddr.family() == AF_INET6)
+		{
+			bindaddr.in6.sin6_port = 0;
+			connaddr.in6.sin6_port = htons(113);
+		}
+		else
+		{
+			bindaddr.in4.sin_port = 0;
+			connaddr.in4.sin_port = htons(113);
+		}
+
+		/* Attempt to bind (ident requests must come from the ip the query is referring to */
+		if (SocketEngine::Bind(this, bindaddr) < 0)
+		{
+			this->Close();
+			throw ModuleException(mod, "failed to bind()");
+		}
+
+		SocketEngine::NonBlocking(GetFd());
+
+		/* Attempt connection (nonblocking) */
+		if (SocketEngine::Connect(this, connaddr) == -1 && errno != EINPROGRESS)
+		{
+			this->Close();
+			throw ModuleException(mod, "connect() failed");
+		}
+
+		/* Add fd to socket engine */
+		if (!SocketEngine::AddFd(this, FD_WANT_NO_READ | FD_WANT_POLL_WRITE))
+		{
+			this->Close();
+			throw ModuleException(mod, "out of fds");
+		}
+	}
+
+	void OnEventHandlerWrite() override
+	{
+		SocketEngine::ChangeEventMask(this, FD_WANT_POLL_READ | FD_WANT_NO_WRITE);
+
+		char req[32];
+
+		/* Build request in the form 'localport,remoteport\r\n' */
+		int req_size;
+		if (user->client_sa.family() == AF_INET6)
+			req_size = snprintf(req, sizeof(req), "%d,%d\r\n",
+				ntohs(user->client_sa.in6.sin6_port), ntohs(user->server_sa.in6.sin6_port));
+		else
+			req_size = snprintf(req, sizeof(req), "%d,%d\r\n",
+				ntohs(user->client_sa.in4.sin_port), ntohs(user->server_sa.in4.sin_port));
+
+		/* Send failed if we didnt write the whole ident request --
+		 * might as well give up if this happens!
+		 */
+		if (SocketEngine::Send(this, req, req_size, 0) < req_size)
+			done = true;
+	}
+
+	void Close()
+	{
+		/* Remove ident socket from engine, and close it, but dont detach it
+		 * from its parent user class, or attempt to delete its memory.
+		 */
+		if (HasFd())
+		{
+			ServerInstance->Logs.Debug(MODNAME, "Close ident socket {}", GetFd());
+			SocketEngine::Close(this);
+		}
+	}
+
+	bool HasResult() const
+	{
+		return done;
+	}
+
+	void OnEventHandlerRead() override
+	{
+		/* We don't really need to buffer for incomplete replies here, since IDENT replies are
+		 * extremely short - there is *no* sane reason it'd be in more than one packet
+		 */
+		char ibuf[256];
+		ssize_t recvresult = SocketEngine::Recv(this, ibuf, sizeof(ibuf)-1, 0);
+
+		/* Close (but don't delete from memory) our socket
+		 * and flag as done since the ident lookup has finished
+		 */
+		Close();
+		done = true;
+
+		/* Cant possibly be a valid response shorter than 3 chars,
+		 * because the shortest possible response would look like: '1,1'
+		 */
+		if (recvresult < 3)
+			return;
+
+		ServerInstance->Logs.Debug(MODNAME, "ReadResponse()");
+
+		/* Truncate at the first null character, but first make sure
+		 * there is at least one null char (at the end of the buffer).
+		 */
+		ibuf[recvresult] = '\0';
+		std::string buf(ibuf);
+
+		/* <2 colons: invalid
+		 *  2 colons: reply is an error
+		 * >3 colons: there is a colon in the ident
+		 */
+		if (std::count(buf.begin(), buf.end(), ':') != 3)
+			return;
+
+		std::string::size_type lastcolon = buf.rfind(':');
+
+		/* Truncate the ident at any characters we don't like, skip leading spaces */
+		for (const auto chr : insp::iterator_range(buf.begin() + lastcolon + 1, buf.end()))
+		{
+			if (result.size() == ServerInstance->Config->Limits.MaxUser)
+				/* Ident is getting too long */
+				break;
+
+			if (chr == ' ')
+				continue;
+
+			/* Add the next char to the result and see if it's still a valid ident,
+			 * according to IsUser(). If it isn't, then erase what we just added and
+			 * we're done.
+			 */
+			result += chr;
+			if (!ServerInstance->IsUser(result))
+			{
+				result.pop_back();
+				break;
+			}
+		}
+	}
+
+	void OnEventHandlerError(int errornum) override
+	{
+		Close();
+		done = true;
+	}
+
+	Cullable::Result Cull() override
+	{
+		Close();
+		return EventHandler::Cull();
+	}
+};
+
+class ModuleIdent final
+	: public Module
+{
+private:
+	unsigned long timeout;
+	bool prefixunqueried;
+	SimpleExtItem<IdentRequestSocket, Cullable::Deleter> socket;
+	IntExtItem state;
+
+	static void PrefixUser(LocalUser* user)
+	{
+		// Check that they haven't been prefixed already.
+		if (user->GetRealUser().front() == '~')
+			return;
+
+		// All invalid usernames are prefixed with a tilde.
+		std::string newuser(user->GetRealUser());
+		newuser.insert(newuser.begin(), '~');
+
+		// If the username is too long then truncate it.
+		if (newuser.length() > ServerInstance->Config->Limits.MaxUser)
+			newuser.erase(ServerInstance->Config->Limits.MaxUser);
+
+		// Apply the new username.
+		user->ChangeRealUser(newuser, user->GetDisplayedUser() == user->GetRealUser());
+	}
+
+public:
+	ModuleIdent()
+		: Module(VF_VENDOR, "Allows the usernames of users to be looked up using the RFC 1413 Identification Protocol.")
+		, socket(this, "ident-socket", ExtensionType::USER)
+		, state(this, "ident-state", ExtensionType::USER)
+	{
+	}
+
+	void ReadConfig(ConfigStatus& status) override
+	{
+		const auto& tag = ServerInstance->Config->ConfValue("ident");
+		timeout = tag->getDuration("timeout", 5, 1, 60);
+		prefixunqueried = tag->getBool("prefixunqueried");
+	}
+
+	void OnChangeRemoteAddress(LocalUser* user) override
+	{
+		IdentRequestSocket* isock = socket.Get(user);
+		if (isock)
+		{
+			// If an ident lookup request was in progress then cancel it.
+			isock->Close();
+			socket.Unset(user);
+		}
+
+		// The ident protocol requires that clients are connecting over a protocol with ports.
+		if (!user->client_sa.is_ip())
+			return;
+
+		// We don't want to look this up once the user has connected.
+		if (user->IsFullyConnected() || user->quitting)
+			return;
+
+		if (!user->GetClass()->config->getBool("useident", true))
+		{
+			state.Set(user, IDENT_SKIPPED);
+			return;
+		}
+
+		user->WriteNotice("*** Looking up your username...");
+
+		try
+		{
+			isock = new IdentRequestSocket(this, user);
+			socket.Set(user, isock);
+		}
+		catch (const ModuleException& e)
+		{
+			ServerInstance->Logs.Debug(MODNAME, "Ident exception: " + e.GetReason());
+		}
+	}
+
+	/* This triggers pretty regularly, we can use it in preference to
+	 * creating a Timer object and especially better than creating a
+	 * Timer per ident lookup!
+	 */
+	ModResult OnCheckReady(LocalUser* user) override
+	{
+		/* Does user have an ident socket attached at all? */
+		IdentRequestSocket* isock = socket.Get(user);
+		if (!isock)
+		{
+			if (prefixunqueried && state.Get(user) == IDENT_SKIPPED)
+			{
+				PrefixUser(user);
+				state.Set(user, IDENT_PREFIXED);
+			}
+			return MOD_RES_PASSTHRU;
+		}
+
+		time_t compare = isock->age + timeout;
+
+		/* Check for timeout of the socket */
+		if (ServerInstance->Time() >= compare)
+		{
+			/* Ident timeout */
+			state.Set(user, IDENT_MISSING);
+			PrefixUser(user);
+			user->WriteNotice("*** Ident lookup timed out, using " + user->GetRealUser() + " instead.");
+		}
+		else if (!isock->HasResult())
+		{
+			// time still good, no result yet... hold the connection
+			return MOD_RES_DENY;
+		}
+
+		/* wooo, got a result (it will be good, or bad) */
+		else if (isock->result.empty())
+		{
+			state.Set(user, IDENT_MISSING);
+			PrefixUser(user);
+			user->WriteNotice("*** Could not find your username, using " + user->GetRealUser() + " instead.");
+		}
+		else
+		{
+			state.Set(user, IDENT_FOUND);
+			user->ChangeRealUser(isock->result, user->GetDisplayedUser() == user->GetRealUser());
+			user->WriteNotice("*** Found your username (" + user->GetRealUser() + ")");
+		}
+
+		isock->Close();
+		socket.Unset(user);
+		return MOD_RES_PASSTHRU;
+	}
+
+	ModResult OnPreChangeConnectClass(LocalUser* user, const std::shared_ptr<ConnectClass>& klass, std::optional<Numeric::Numeric>& errnum) override
+	{
+		if (klass->config->getBool("requireident") && state.Get(user) != IDENT_FOUND)
+		{
+			ServerInstance->Logs.Debug("CONNECTCLASS", "The {} connect class is not suitable as it requires an identd response.",
+				klass->GetName());
+			return MOD_RES_DENY;
+		}
+		return MOD_RES_PASSTHRU;
+	}
+
+	void OnUserConnect(LocalUser* user) override
+	{
+		// Clear this as it is no longer necessary.
+		state.Unset(user);
+	}
+};
+
+MODULE_INIT(ModuleIdent)