/*
* InspIRCd -- Internet Relay Chat Daemon
*
* Copyright (C) 2021 Dominic Hamon
* Copyright (C) 2013, 2018-2023, 2025 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)
