/* * InspIRCd -- Internet Relay Chat Daemon * * Copyright (C) 2021 Dominic Hamon * Copyright (C) 2013, 2018-2023 Sadie Powell * Copyright (C) 2012-2013 Robby * Copyright (C) 2012, 2014-2015 Attila Molnar * Copyright (C) 2009-2010 Daniel De Graaf * Copyright (C) 2008 Robin Burchell * Copyright (C) 2007 John Brooks * Copyright (C) 2007 Dennis Friis * Copyright (C) 2007 Craig Edwards * * 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 . */ #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 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& klass, std::optional& 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)