Add a CapReference class for the message-tags capability.

[user/henk/code/inspircd.git] / include / modules.h

/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2019 iwalkalone <iwalkalone69@gmail.com>
 *   Copyright (C) 2013 Adam <Adam@anope.org>
 *   Copyright (C) 2012-2016, 2018 Attila Molnar <attilamolnar@hush.com>
 *   Copyright (C) 2012-2013, 2016-2020 Sadie Powell <sadie@witchery.services>
 *   Copyright (C) 2012 Robby <robby@chatbelgie.be>
 *   Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org>
 *   Copyright (C) 2009 Uli Schlachter <psychon@inspircd.org>
 *   Copyright (C) 2008 Thomas Stagner <aquanight@inspircd.org>
 *   Copyright (C) 2007-2009 Robin Burchell <robin+git@viroteck.net>
 *   Copyright (C) 2007-2008, 2010 Craig Edwards <brain@inspircd.org>
 *   Copyright (C) 2007 Oliver Lupton <om@inspircd.org>
 *   Copyright (C) 2007 Dennis Friis <peavey@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 "moduledefs.h"
#include "dynamic.h"
#include "base.h"
#include "ctables.h"
#include "inspsocket.h"
#include "timer.h"
#include "mode.h"

/** Used to specify the behaviour of a module. */
enum ModuleFlags
{
        /** The module has no special attributes. */
        VF_NONE = 0,

        /** The module is a coremod and can be assumed to be loaded on all servers. */
        VF_CORE = 1,

        /* The module is included with InspIRCd. */
        VF_VENDOR = 2,

        /** The module MUST be loaded on all servers on a network to link. */
        VF_COMMON = 4,

        /** The module SHOULD be loaded on all servers on a network for consistency. */
        VF_OPTCOMMON = 8
};

#define MOD_RES_ALLOW (ModResult(1))
#define MOD_RES_PASSTHRU (ModResult(0))
#define MOD_RES_DENY (ModResult(-1))

/** Used to represent an allow/deny module result.
 * Not constructed as an enum because it reverses the value logic of some functions;
 * the compiler will inline accesses to have the same efficiency as integer operations.
 */
struct ModResult {
        int res;
        ModResult() : res(0) {}
        explicit ModResult(int r) : res(r) {}
        inline bool operator==(const ModResult& r) const
        {
                return res == r.res;
        }
        inline bool operator!=(const ModResult& r) const
        {
                return res != r.res;
        }
        inline bool operator!() const
        {
                return !res;
        }
        inline bool check(bool def) const
        {
                return (res == 1 || (res == 0 && def));
        }
        /**
         * Merges two results, preferring ALLOW to DENY
         */
        inline ModResult operator+(const ModResult& r) const
        {
                if (res == r.res || r.res == 0)
                        return *this;
                if (res == 0)
                        return r;
                // they are different, and neither is passthru
                return MOD_RES_ALLOW;
        }
};

/**
 * This #define allows us to call a method in all
 * loaded modules in a readable simple way, e.g.:
 * 'FOREACH_MOD(OnConnect,(user));'
 */
#define FOREACH_MOD(y,x) do { \
        const Module::List& _handlers = ServerInstance->Modules->EventHandlers[I_ ## y]; \
        for (Module::List::const_reverse_iterator _i = _handlers.rbegin(), _next; _i != _handlers.rend(); _i = _next) \
        { \
                _next = _i+1; \
                try \
                { \
                        if (!(*_i)->dying) \
                                (*_i)->y x ; \
                } \
                catch (CoreException& modexcept) \
                { \
                        ServerInstance->Logs->Log("MODULE", LOG_DEFAULT, "Exception caught: " + modexcept.GetReason()); \
                } \
        } \
} while (0);

/**
 * Custom module result handling loop. This is a paired macro, and should only
 * be used with while_each_hook.
 *
 * See src/channels.cpp for an example of use.
 */
#define DO_EACH_HOOK(n,v,args) \
do { \
        const Module::List& _handlers = ServerInstance->Modules->EventHandlers[I_ ## n]; \
        for (Module::List::const_reverse_iterator _i = _handlers.rbegin(), _next; _i != _handlers.rend(); _i = _next) \
        { \
                _next = _i+1; \
                try \
                { \
                        if (!(*_i)->dying) \
                                v = (*_i)->n args;

#define WHILE_EACH_HOOK(n) \
                } \
                catch (CoreException& except_ ## n) \
                { \
                        ServerInstance->Logs->Log("MODULE", LOG_DEFAULT, "Exception caught: " + (except_ ## n).GetReason()); \
                } \
        } \
} while(0)

/**
 * Module result iterator
 * Runs the given hook until some module returns a useful result.
 *
 * Example: ModResult result;
 * FIRST_MOD_RESULT(OnUserPreNick, result, (user, newnick))
 */
#define FIRST_MOD_RESULT(n,v,args) do { \
        v = MOD_RES_PASSTHRU; \
        DO_EACH_HOOK(n,v,args) \
        { \
                if (v != MOD_RES_PASSTHRU) \
                        break; \
        } \
        WHILE_EACH_HOOK(n); \
} while (0)

/** Holds a module's Version information.
 * The members (set by the constructor only) indicate details as to the version number
 * of a module. A class of type Version is returned by the GetVersion method of the Module class.
 */
class CoreExport Version
{
 public:
        /** Module description
         */
        const std::string description;

        /** Flags
         */
        const int Flags;

        /** Server linking description string */
        const std::string link_data;

        /** Simple module version */
        Version(const std::string &desc, int flags = VF_NONE);

        /** Complex version information, including linking compatability data */
        Version(const std::string &desc, int flags, const std::string& linkdata);
};

class CoreExport DataProvider : public ServiceProvider
{
 public:
        DataProvider(Module* Creator, const std::string& Name)
                : ServiceProvider(Creator, Name, SERVICE_DATA) {}
};

/** Priority types which can be used by Module::Prioritize()
 */
enum Priority { PRIORITY_FIRST, PRIORITY_LAST, PRIORITY_BEFORE, PRIORITY_AFTER };

/** Implementation-specific flags which may be set in Module::Implements()
 */
enum Implementation
{
        I_OnUserConnect, I_OnUserPreQuit, I_OnUserQuit, I_OnUserDisconnect, I_OnUserJoin, I_OnUserPart,
        I_OnSendSnotice, I_OnUserPreJoin, I_OnUserPreKick, I_OnUserKick, I_OnOper,
        I_OnUserPreInvite, I_OnUserInvite, I_OnUserPreMessage, I_OnUserPreNick,
        I_OnUserPostMessage, I_OnUserMessageBlocked, I_OnMode, I_OnShutdown,
        I_OnDecodeMetaData, I_OnAcceptConnection, I_OnUserInit, I_OnUserPostInit,
        I_OnChangeHost, I_OnChangeRealName, I_OnAddLine, I_OnDelLine, I_OnExpireLine,
        I_OnUserPostNick, I_OnPreMode, I_On005Numeric, I_OnKill, I_OnLoadModule,
        I_OnUnloadModule, I_OnBackgroundTimer, I_OnPreCommand, I_OnCheckReady, I_OnCheckInvite,
        I_OnRawMode, I_OnCheckKey, I_OnCheckLimit, I_OnCheckBan, I_OnCheckChannelBan, I_OnExtBanCheck,
        I_OnPreChangeHost, I_OnPreTopicChange, I_OnConnectionFail,
        I_OnPostTopicChange, I_OnPostConnect, I_OnPostDeoper,
        I_OnPreChangeRealName, I_OnUserRegister, I_OnChannelPreDelete, I_OnChannelDelete,
        I_OnPostOper, I_OnPostCommand, I_OnCommandBlocked, I_OnPostJoin,
        I_OnBuildNeighborList, I_OnGarbageCollect, I_OnSetConnectClass,
        I_OnUserMessage, I_OnPassCompare, I_OnNumeric,
        I_OnPreRehash, I_OnModuleRehash, I_OnChangeIdent, I_OnSetUserIP,
        I_OnServiceAdd, I_OnServiceDel, I_OnUserWrite,
        I_END
};

/** Base class for all InspIRCd modules
 *  This class is the base class for InspIRCd modules. All modules must inherit from this class,
 *  its methods will be called when irc server events occur. class inherited from module must be
 *  instantiated by the ModuleFactory class (see relevent section) for the module to be initialised.
 */
class CoreExport Module : public classbase, public usecountbase
{
        /** Detach an event from this module
         * @param i Event type to detach
         */
        void DetachEvent(Implementation i);

 public:
        /** A list of modules. */
        typedef std::vector<Module*> List;

        /** File that this module was loaded from
         */
        std::string ModuleSourceFile;

        /** Reference to the dlopen() value
         */
        DLLManager* ModuleDLLManager;

        /** If true, this module will be unloaded soon, further unload attempts will fail
         * Value is used by the ModuleManager internally, you should not modify it
         */
        bool dying;

        /** Default constructor.
         * Creates a module class. Don't do any type of hook registration or checks
         * for other modules here; do that in init().
         */
        Module();

        /** Module setup
         * \exception ModuleException Throwing this class, or any class derived from ModuleException, causes loading of the module to abort.
         */
        virtual void init() {}

        /** Clean up prior to destruction
         * If you override, you must call this AFTER your module's cleanup
         */
        CullResult cull() CXX11_OVERRIDE;

        /** Default destructor.
         * destroys a module class
         */
        virtual ~Module();

        virtual void Prioritize()
        {
        }

        /** This method is called when you should reload module specific configuration:
         * on boot, on a /REHASH and on module load.
         * @param status The current status, can be inspected for more information;
         * also used for reporting configuration errors and warnings.
         */
        virtual void ReadConfig(ConfigStatus& status);

        /** Returns the version number of a Module.
         * The method should return a Version object with its version information assigned via
         * Version::Version
         */
        virtual Version GetVersion() = 0;

        /** Called when a user connects.
         * The details of the connecting user are available to you in the parameter User *user
         * @param user The user who is connecting
         */
        virtual void OnUserConnect(LocalUser* user);

        /** Called when before a user quits.
         * The details of the exiting user are available to you in the parameter User *user
         * This event is only called when the user is fully registered when they quit. To catch
         * raw disconnections, use the OnUserDisconnect method.
         * @param user The user who is quitting
         * @param message The user's quit message (as seen by non-opers)
         * @param oper_message The user's quit message (as seen by opers)
         */
        virtual ModResult OnUserPreQuit(LocalUser* user, std::string& message, std::string& oper_message);

        /** Called when a user quits.
         * The details of the exiting user are available to you in the parameter User *user
         * This event is only called when the user is fully registered when they quit. To catch
         * raw disconnections, use the OnUserDisconnect method.
         * @param user The user who is quitting
         * @param message The user's quit message (as seen by non-opers)
         * @param oper_message The user's quit message (as seen by opers)
         */
        virtual void OnUserQuit(User* user, const std::string &message, const std::string &oper_message);

        /** Called whenever a user's socket is closed.
         * The details of the exiting user are available to you in the parameter User *user
         * This event is called for all users, registered or not, as a cleanup method for modules
         * which might assign resources to user, such as dns lookups, objects and sockets.
         * @param user The user who is disconnecting
         */
        virtual void OnUserDisconnect(LocalUser* user);

        /** Called whenever a channel is about to be deleted
         * @param chan The channel being deleted
         * @return An integer specifying whether or not the channel may be deleted. 0 for yes, 1 for no.
         */
        virtual ModResult OnChannelPreDelete(Channel *chan);

        /** Called whenever a channel is deleted, either by QUIT, KICK or PART.
         * @param chan The channel being deleted
         */
        virtual void OnChannelDelete(Channel* chan);

        /** Called when a user joins a channel.
         * The details of the joining user are available to you in the parameter User *user,
         * and the details of the channel they have joined is available in the variable Channel *channel
         * @param memb The channel membership being created
         * @param sync This is set to true if the JOIN is the result of a network sync and the remote user is being introduced
         * to a channel due to the network sync.
         * @param created This is true if the join created the channel
         * @param except_list A list of users not to send to.
         */
        virtual void OnUserJoin(Membership* memb, bool sync, bool created, CUList& except_list);

        /** Called after a user joins a channel
         * Identical to OnUserJoin, but called immediately afterwards, when any linking module has
         * seen the join.
         * @param memb The channel membership created
         */
        virtual void OnPostJoin(Membership* memb);

        /** Called when a user parts a channel.
         * The details of the leaving user are available to you in the parameter User *user,
         * and the details of the channel they have left is available in the variable Channel *channel
         * @param memb The channel membership being destroyed
         * @param partmessage The part message, or an empty string (may be modified)
         * @param except_list A list of users to not send to.
         */
        virtual void OnUserPart(Membership* memb, std::string &partmessage, CUList& except_list);

        /** Called on rehash.
         * This method is called prior to a /REHASH or when a SIGHUP is received from the operating
         * system. This is called in all cases -- including when this server will not execute the
         * rehash because it is directed at a remote server.
         *
         * @param user The user performing the rehash, if any. If this is server initiated, the value of
         * this variable will be NULL.
         * @param parameter The (optional) parameter given to REHASH from the user. Empty when server
         * initiated.
         */
        virtual void OnPreRehash(User* user, const std::string &parameter);

        /** Called on rehash.
         * This method is called when a user initiates a module-specific rehash. This can be used to do
         * expensive operations (such as reloading SSL certificates) that are not executed on a normal
         * rehash for efficiency. A rehash of this type does not reload the core configuration.
         *
         * @param user The user performing the rehash.
         * @param parameter The parameter given to REHASH
         */
        virtual void OnModuleRehash(User* user, const std::string &parameter);

        /** Called whenever a snotice is about to be sent to a snomask.
         * snomask and type may both be modified; the message may not.
         * @param snomask The snomask the message is going to (e.g. 'A')
         * @param type The textual description the snomask will go to (e.g. 'OPER')
         * @param message The text message to be sent via snotice
         * @return 1 to block the snotice from being sent entirely, 0 else.
         */
        virtual ModResult OnSendSnotice(char &snomask, std::string &type, const std::string &message);

        /** Called whenever a user is about to join a channel, before any processing is done.
         * Returning a value of 1 from this function stops the process immediately, causing no
         * output to be sent to the user by the core. If you do this you must produce your own numerics,
         * notices etc. This is useful for modules which may want to mimic +b, +k, +l etc. Returning -1 from
         * this function forces the join to be allowed, bypassing restrictions such as banlists, invite, keys etc.
         *
         * IMPORTANT NOTE!
         *
         * If the user joins a NEW channel which does not exist yet, OnUserPreJoin will be called BEFORE the channel
         * record is created. This will cause Channel* chan to be NULL. There is very little you can do in form of
         * processing on the actual channel record at this point, however the channel NAME will still be passed in
         * char* cname, so that you could for example implement a channel blacklist or whitelist, etc.
         * @param user The user joining the channel
         * @param chan If the  channel is a new channel, this will be NULL, otherwise it will be a pointer to the channel being joined
         * @param cname The channel name being joined. For new channels this is valid where chan is not.
         * @param privs A string containing the users privilages when joining the channel. For new channels this will contain "o".
         * You may alter this string to alter the user's modes on the channel.
         * @param keygiven The key given to join the channel, or an empty string if none was provided
         * @return 1 To prevent the join, 0 to allow it.
         */
        virtual ModResult OnUserPreJoin(LocalUser* user, Channel* chan, const std::string& cname, std::string& privs, const std::string& keygiven);

        /** Called whenever a user is about to be kicked.
         * Returning a value of 1 from this function stops the process immediately, causing no
         * output to be sent to the user by the core. If you do this you must produce your own numerics,
         * notices etc.
         * @param source The user issuing the kick
         * @param memb The channel membership of the user who is being kicked.
         * @param reason The kick reason
         * @return 1 to prevent the kick, 0 to continue normally, -1 to explicitly allow the kick regardless of normal operation
         */
        virtual ModResult OnUserPreKick(User* source, Membership* memb, const std::string &reason);

        /** Called whenever a user is kicked.
         * If this method is called, the kick is already underway and cannot be prevented, so
         * to prevent a kick, please use Module::OnUserPreKick instead of this method.
         * @param source The user issuing the kick
         * @param memb The channel membership of the user who was kicked.
         * @param reason The kick reason
         * @param except_list A list of users to not send to.
         */
        virtual void OnUserKick(User* source, Membership* memb, const std::string &reason, CUList& except_list);

        /** Called whenever a user opers locally.
         * The User will contain the oper mode 'o' as this function is called after any modifications
         * are made to the user's structure by the core.
         * @param user The user who is opering up
         * @param opertype The opers type name
         */
        virtual void OnOper(User* user, const std::string &opertype);

        /** Called after a user opers locally.
         * This is identical to Module::OnOper(), except it is called after OnOper so that other modules
         * can be gauranteed to already have processed the oper-up, for example m_spanningtree has sent
         * out the OPERTYPE, etc.
         * @param user The user who is opering up
         * @param opername The name of the oper that the user is opering up to. Only valid locally. Empty string otherwise.
         * @param opertype The opers type name
         */
        virtual void OnPostOper(User* user, const std::string &opername, const std::string &opertype);

        /** Called after a user deopers locally.
         * @param user The user who has deopered.
         */
        virtual void OnPostDeoper(User* user);

        /** Called whenever a user is about to invite another user into a channel, before any processing is done.
         * Returning 1 from this function stops the process immediately, causing no
         * output to be sent to the user by the core. If you do this you must produce your own numerics,
         * notices etc. This is useful for modules which may want to filter invites to channels.
         * @param source The user who is issuing the INVITE
         * @param dest The user being invited
         * @param channel The channel the user is being invited to
         * @param timeout The time the invite will expire (0 == never)
         * @return 1 to deny the invite, 0 to check whether or not the user has permission to invite, -1 to explicitly allow the invite
         */
        virtual ModResult OnUserPreInvite(User* source,User* dest,Channel* channel, time_t timeout);

        /** Called after a user has been successfully invited to a channel.
         * You cannot prevent the invite from occuring using this function, to do that,
         * use OnUserPreInvite instead.
         * @param source The user who is issuing the INVITE
         * @param dest The user being invited
         * @param channel The channel the user is being invited to
         * @param timeout The time the invite will expire (0 == never)
         * @param notifyrank Rank required to get an invite announcement (if enabled)
         * @param notifyexcepts List of users to not send the default NOTICE invite announcement to
         */
        virtual void OnUserInvite(User* source, User* dest, Channel* channel, time_t timeout, unsigned int notifyrank, CUList& notifyexcepts);

        /** Called before a user sends a message to a channel, a user, or a server glob mask.
         * @param user The user sending the message.
         * @param target The target of the message. This can either be a channel, a user, or a server
         *               glob mask.
         * @param details Details about the message such as the message text and type. See the
         *                MessageDetails class for more information.
         * @return MOD_RES_ALLOW to explicitly allow the message, MOD_RES_DENY to explicitly deny the
         *         message, or MOD_RES_PASSTHRU to let another module handle the event.
         */
        virtual ModResult OnUserPreMessage(User* user, const MessageTarget& target, MessageDetails& details);

        /** Called when sending a message to all "neighbors" of a given user -
         * that is, all users that share a common channel. This is used in
         * commands such as NICK, QUIT, etc.
         * @param source The source of the message
         * @param include_c Channels to scan for users to include
         * @param exceptions Map of user->bool that overrides the inclusion decision
         *
         * Set exceptions[user] = true to include, exceptions[user] = false to exclude
         */
        virtual void OnBuildNeighborList(User* source, IncludeChanList& include_c, std::map<User*, bool>& exceptions);

        /** Called before local nickname changes. This can be used to implement Q-lines etc.
         * If your method returns nonzero, the nickchange is silently forbidden, and it is down to your
         * module to generate some meaninful output.
         * @param user The username changing their nick
         * @param newnick Their new nickname
         * @return 1 to deny the change, 0 to allow
         */
        virtual ModResult OnUserPreNick(LocalUser* user, const std::string& newnick);

        /** Called immediately after a user sends a message to a channel, a user, or a server glob mask.
         * @param user The user sending the message.
         * @param target The target of the message. This can either be a channel, a user, or a server
         *               glob mask.
         * @param details Details about the message such as the message text and type. See the
         *                MessageDetails class for more information.
         */
        virtual void OnUserPostMessage(User* user, const MessageTarget& target, const MessageDetails& details);

        /** Called immediately before a user sends a message to a channel, a user, or a server glob mask.
         * @param user The user sending the message.
         * @param target The target of the message. This can either be a channel, a user, or a server
         *               glob mask.
         * @param details Details about the message such as the message text and type. See the
         *                MessageDetails class for more information.
         */
        virtual void OnUserMessage(User* user, const MessageTarget& target, const MessageDetails& details);

        /** Called when a message sent by a user to a channel, a user, or a server glob mask is blocked.
         * @param user The user sending the message.
         * @param target The target of the message. This can either be a channel, a user, or a server
         *               glob mask.
         * @param details Details about the message such as the message text and type. See the
         *                MessageDetails class for more information.
         */
        virtual void OnUserMessageBlocked(User* user, const MessageTarget& target, const MessageDetails& details);

        /** Called after every MODE command sent from a user
         * Either the usertarget or the chantarget variable contains the target of the modes,
         * the actual target will have a non-NULL pointer.
         * All changed modes are available in the changelist object.
         * @param user The user sending the MODEs
         * @param usertarget The target user of the modes, NULL if the target is a channel
         * @param chantarget The target channel of the modes, NULL if the target is a user
         * @param changelist The changed modes.
         * @param processflags Flags passed to ModeParser::Process(), see ModeParser::ModeProcessFlags
         * for the possible flags.
         */
        virtual void OnMode(User* user, User* usertarget, Channel* chantarget, const Modes::ChangeList& changelist, ModeParser::ModeProcessFlag processflags);

        /** Allows module data, sent via ProtoSendMetaData, to be decoded again by a receiving module.
         * Please see src/modules/m_swhois.cpp for a working example of how to use this method call.
         * @param target The Channel* or User* that data should be added to
         * @param extname The extension name which is being sent
         * @param extdata The extension data, encoded at the other end by an identical module
         */
        virtual void OnDecodeMetaData(Extensible* target, const std::string &extname, const std::string &extdata);

        /** Called whenever a user's hostname is changed.
         * This event triggers after the host has been set.
         * @param user The user whos host is being changed
         * @param newhost The new hostname being set
         */
        virtual void OnChangeHost(User* user, const std::string &newhost);

        /** Called whenever a user's real name is changed.
         * This event triggers after the name has been set.
         * @param user The user who's real name is being changed
         * @param real The new real name being set on the user
         */
        virtual void OnChangeRealName(User* user, const std::string& real);

        /** Called whenever a user's IDENT is changed.
         * This event triggers after the name has been set.
         * @param user The user who's IDENT is being changed
         * @param ident The new IDENT being set on the user
         */
        virtual void OnChangeIdent(User* user, const std::string &ident);

        /** Called whenever an xline is added by a local user.
         * This method is triggered after the line is added.
         * @param source The sender of the line or NULL for local server
         * @param line The xline being added
         */
        virtual void OnAddLine(User* source, XLine* line);

        /** Called whenever an xline is deleted MANUALLY. See OnExpireLine for expiry.
         * This method is triggered after the line is deleted.
         * @param source The user removing the line or NULL for local server
         * @param line the line being deleted
         */
        virtual void OnDelLine(User* source, XLine* line);

        /** Called whenever an xline expires.
         * This method is triggered after the line is deleted.
         * @param line The line being deleted.
         */
        virtual void OnExpireLine(XLine *line);

        /** Called before the module is unloaded to clean up extensibles.
         * This method is called once for every channel, membership, and user.
         * so that you can clear up any data relating to the specified extensible.
         * @param type The type of extensible being cleaned up. If this is EXT_CHANNEL
         *             then item is a Channel*, EXT_MEMBERSHIP then item is a Membership*,
         *             and EXT_USER then item is a User*.
         * @param item A pointer to the extensible which is being cleaned up.
         */
        virtual void OnCleanup(ExtensionItem::ExtensibleType type, Extensible* item);

        /** Called after any nickchange, local or remote. This can be used to track users after nickchanges
         * have been applied. Please note that although you can see remote nickchanges through this function, you should
         * NOT make any changes to the User if the user is a remote user as this may cause a desnyc.
         * check user->server before taking any action (including returning nonzero from the method).
         * Because this method is called after the nickchange is taken place, no return values are possible
         * to indicate forbidding of the nick change. Use OnUserPreNick for this.
         * @param user The user changing their nick
         * @param oldnick The old nickname of the user before the nickchange
         */
        virtual void OnUserPostNick(User* user, const std::string &oldnick);

        /** Called before a mode change via the MODE command, to allow a single access check for
         * a full mode change (use OnRawMode to check individual modes)
         *
         * Returning MOD_RES_ALLOW will skip prefix level checks, but can be overridden by
         * OnRawMode for each individual mode
         *
         * @param source the user making the mode change
         * @param dest the user destination of the umode change (NULL if a channel mode)
         * @param channel the channel destination of the mode change
         * @param modes Modes being changed, can be edited
         */
        virtual ModResult OnPreMode(User* source, User* dest, Channel* channel, Modes::ChangeList& modes);

        /** Called when a 005 numeric is about to be output.
         * The module should modify the 005 numeric if needed to indicate its features.
        * @param tokens The 005 map to be modified if neccessary.
        */
        virtual void On005Numeric(std::map<std::string, std::string>& tokens);

        /** Called when a client is disconnected by KILL.
         * If a client is killed by a server, e.g. a nickname collision or protocol error,
         * source is NULL.
         * Return 1 from this function to prevent the kill, and 0 from this function to allow
         * it as normal. If you prevent the kill no output will be sent to the client, it is
         * down to your module to generate this information.
         * NOTE: It is NOT advisable to stop kills which originate from servers or remote users.
         * If you do so youre risking race conditions, desyncs and worse!
         * @param source The user sending the KILL
         * @param dest The user being killed
         * @param reason The kill reason
         * @return 1 to prevent the kill, 0 to allow
         */
        virtual ModResult OnKill(User* source, User* dest, const std::string &reason);

        /** Called whenever a module is loaded.
         * mod will contain a pointer to the module, and string will contain its name,
         * for example m_widgets.so. This function is primary for dependency checking,
         * your module may decide to enable some extra features if it sees that you have
         * for example loaded "m_killwidgets.so" with "m_makewidgets.so". It is highly
         * recommended that modules do *NOT* bail if they cannot satisfy dependencies,
         * but instead operate under reduced functionality, unless the dependency is
         * absolutely neccessary (e.g. a module that extends the features of another
         * module).
         * @param mod A pointer to the new module
         */
        virtual void OnLoadModule(Module* mod);

        /** Called whenever a module is unloaded.
         * mod will contain a pointer to the module, and string will contain its name,
         * for example m_widgets.so. This function is primary for dependency checking,
         * your module may decide to enable some extra features if it sees that you have
         * for example loaded "m_killwidgets.so" with "m_makewidgets.so". It is highly
         * recommended that modules do *NOT* bail if they cannot satisfy dependencies,
         * but instead operate under reduced functionality, unless the dependency is
         * absolutely neccessary (e.g. a module that extends the features of another
         * module).
         * @param mod Pointer to the module being unloaded (still valid)
         */
        virtual void OnUnloadModule(Module* mod);

        /** Called once every five seconds for background processing.
         * This timer can be used to control timed features. Its period is not accurate
         * enough to be used as a clock, but it is gauranteed to be called at least once in
         * any five second period, directly from the main loop of the server.
         * @param curtime The current timer derived from time(2)
         */
        virtual void OnBackgroundTimer(time_t curtime);

        /** Called whenever any command is about to be executed.
         * This event occurs for all registered commands, wether they are registered in the core,
         * or another module, and for invalid commands. Invalid commands may only be sent to this
         * function when the value of validated is false. By returning 1 from this method you may prevent the
         * command being executed. If you do this, no output is created by the core, and it is
         * down to your module to produce any output neccessary.
         * Note that unless you return 1, you should not destroy any structures (e.g. by using
         * InspIRCd::QuitUser) otherwise when the command's handler function executes after your
         * method returns, it will be passed an invalid pointer to the user object and crash!)
         * @param command The command being executed
         * @param parameters An array of array of characters containing the parameters for the command
         * @param user the user issuing the command
         * @param validated True if the command has passed all checks, e.g. it is recognised, has enough parameters, the user has permission to execute it, etc.
         * You should only change the parameter list and command string if validated == false (e.g. before the command lookup occurs).
         * @return 1 to block the command, 0 to allow
         */
        virtual ModResult OnPreCommand(std::string& command, CommandBase::Params& parameters, LocalUser* user, bool validated);

        /** Called after any command has been executed.
         * This event occurs for all registered commands, wether they are registered in the core,
         * or another module, but it will not occur for invalid commands (e.g. ones which do not
         * exist within the command table). The result code returned by the command handler is
         * provided.
         * @param command The command being executed
         * @param parameters An array of array of characters containing the parameters for the command
         * @param user the user issuing the command
         * @param result The return code given by the command handler, one of CMD_SUCCESS or CMD_FAILURE
         * @param loop Whether the command is being called from LoopCall or directly.
         */
        virtual void OnPostCommand(Command* command, const CommandBase::Params& parameters, LocalUser* user, CmdResult result, bool loop);

        /** Called when a command was blocked before it could be executed.
         * @param command The command being executed.
         * @param parameters The parameters for the command.
         * @param user The user issuing the command.
         */
        virtual void OnCommandBlocked(const std::string& command, const CommandBase::Params& parameters, LocalUser* user);

        /** Called after a user object is initialised and added to the user list.
         * When this is called the user has not had their I/O hooks checked or had their initial
         * connect class assigned and may not yet have a serialiser. You probably want to use
         * the OnUserPostInit or OnUserSetIP hooks instead of this one.
         * @param user The connecting user.
         */
        virtual void OnUserInit(LocalUser* user);

        /** Called after a user object has had their I/O hooks checked, their initial connection
         * class assigned, and had a serialiser set.
         * @param user The connecting user.
         */
        virtual void OnUserPostInit(LocalUser* user);

        /** Called to check if a user who is connecting can now be allowed to register
         * If any modules return false for this function, the user is held in the waiting
         * state until all modules return true. For example a module which implements ident
         * lookups will continue to return false for a user until their ident lookup is completed.
         * Note that the registration timeout for a user overrides these checks, if the registration
         * timeout is reached, the user is disconnected even if modules report that the user is
         * not ready to connect.
         * @param user The user to check
         * @return true to indicate readiness, false if otherwise
         */
        virtual ModResult OnCheckReady(LocalUser* user);

        /** Called whenever a user is about to register their connection (e.g. before the user
         * is sent the MOTD etc). Modules can use this method if they are performing a function
         * which must be done before the actual connection is completed (e.g. ident lookups,
         * dnsbl lookups, etc).
         * Note that you should NOT delete the user record here by causing a disconnection!
         * Use OnUserConnect for that instead.
         * @param user The user registering
         * @return 1 to indicate user quit, 0 to continue
         */
        virtual ModResult OnUserRegister(LocalUser* user);

        /** Called whenever a user joins a channel, to determine if invite checks should go ahead or not.
         * This method will always be called for each join, wether or not the channel is actually +i, and
         * determines the outcome of an if statement around the whole section of invite checking code.
         * return 1 to explicitly allow the join to go ahead or 0 to ignore the event.
         * @param user The user joining the channel
         * @param chan The channel being joined
         * @return 1 to explicitly allow the join, 0 to proceed as normal
         */
        virtual ModResult OnCheckInvite(User* user, Channel* chan);

        /** Called whenever a mode character is processed.
         * Return 1 from this function to block the mode character from being processed entirely.
         * @param user The user who is sending the mode
         * @param chan The channel the mode is being sent to (or NULL if a usermode)
         * @param mh The mode handler for the mode being changed
         * @param param The parameter for the mode or an empty string
         * @param adding true of the mode is being added, false if it is being removed
         * @return ACR_DENY to deny the mode, ACR_DEFAULT to do standard mode checking, and ACR_ALLOW
         * to skip all permission checking. Please note that for remote mode changes, your return value
         * will be ignored!
         */
        virtual ModResult OnRawMode(User* user, Channel* chan, ModeHandler* mh, const std::string& param, bool adding);

        /** Called whenever a user joins a channel, to determine if key checks should go ahead or not.
         * This method will always be called for each join, wether or not the channel is actually +k, and
         * determines the outcome of an if statement around the whole section of key checking code.
         * if the user specified no key, the keygiven string will be a valid but empty value.
         * return 1 to explicitly allow the join to go ahead or 0 to ignore the event.
         * @param user The user joining the channel
         * @param chan The channel being joined
         * @param keygiven The key given on joining the channel.
         * @return 1 to explicitly allow the join, 0 to proceed as normal
         */
        virtual ModResult OnCheckKey(User* user, Channel* chan, const std::string &keygiven);

        /** Called whenever a user joins a channel, to determine if channel limit checks should go ahead or not.
         * This method will always be called for each join, wether or not the channel is actually +l, and
         * determines the outcome of an if statement around the whole section of channel limit checking code.
         * return 1 to explicitly allow the join to go ahead or 0 to ignore the event.
         * @param user The user joining the channel
         * @param chan The channel being joined
         * @return 1 to explicitly allow the join, 0 to proceed as normal
         */
        virtual ModResult OnCheckLimit(User* user, Channel* chan);

        /**
         * Checks for a user's ban from the channel
         * @param user The user to check
         * @param chan The channel to check in
         * @return MOD_RES_DENY to mark as banned, MOD_RES_ALLOW to skip the
         * ban check, or MOD_RES_PASSTHRU to check bans normally
         */
        virtual ModResult OnCheckChannelBan(User* user, Channel* chan);

        /**
         * Checks for a user's match of a single ban
         * @param user The user to check for match
         * @param chan The channel on which the match is being checked
         * @param mask The mask being checked
         * @return MOD_RES_DENY to mark as banned, MOD_RES_ALLOW to skip the
         * ban check, or MOD_RES_PASSTHRU to check bans normally
         */
        virtual ModResult OnCheckBan(User* user, Channel* chan, const std::string& mask);

        /** Checks for a match on a given extban type
         * @return MOD_RES_DENY to mark as banned, MOD_RES_ALLOW to skip the
         * ban check, or MOD_RES_PASSTHRU to check bans normally
         */
        virtual ModResult OnExtBanCheck(User* user, Channel* chan, char type);

        /** Called whenever a change of a local users displayed host is attempted.
         * Return 1 to deny the host change, or 0 to allow it.
         * @param user The user whos host will be changed
         * @param newhost The new hostname
         * @return 1 to deny the host change, 0 to allow
         */
        virtual ModResult OnPreChangeHost(LocalUser* user, const std::string &newhost);

        /** Called whenever a change of a local users real name is attempted.
         * return MOD_RES_DENY to deny the name change, or MOD_RES_ALLOW to allow it.
         * @param user The user whos real name will be changed
         * @param newhost The new real name.
         * @return MOD_RES_DENY to deny the real name change, MOD_RES_ALLOW to allow
         */
        virtual ModResult OnPreChangeRealName(LocalUser* user, const std::string &newhost);

        /** Called before a topic is changed.
         * Return 1 to deny the topic change, 0 to check details on the change, -1 to let it through with no checks
         * As with other 'pre' events, you should only ever block a local event.
         * @param user The user changing the topic
         * @param chan The channels who's topic is being changed
         * @param topic The actual topic text
         * @return 1 to block the topic change, 0 to allow
         */
        virtual ModResult OnPreTopicChange(User* user, Channel* chan, const std::string &topic);

        /** Called whenever a topic has been changed.
         * To block topic changes you must use OnPreTopicChange instead.
         * @param user The user changing the topic
         * @param chan The channels who's topic is being changed
         * @param topic The actual topic text
         */
        virtual void OnPostTopicChange(User* user, Channel* chan, const std::string &topic);

        /** Called whenever a password check is to be made. Replaces the old OldOperCompare API.
         * The password field (from the config file) is in 'password' and is to be compared against
         * 'input'. This method allows for encryption of passwords (oper, connect:allow, die/restart, etc).
         * You should return a nonzero value to override the normal comparison, or zero to pass it on.
         * @param ex The object that's causing the authentication (User* for \<oper> \<connect:allow> etc, Server* for \<link>).
         * @param password The password from the configuration file (the password="" value).
         * @param input The password entered by the user or whoever.
         * @param hashtype The hash value from the config
         * @return 0 to do nothing (pass on to next module/default), 1 == password is OK, -1 == password is not OK
         */
        virtual ModResult OnPassCompare(Extensible* ex, const std::string &password, const std::string &input, const std::string& hashtype);

        /** Called after a user has fully connected and all modules have executed OnUserConnect
         * This event is informational only. You should not change any user information in this
         * event. To do so, use the OnUserConnect method to change the state of local users.
         * This is called for both local and remote users.
         * @param user The user who is connecting
         */
        virtual void OnPostConnect(User* user);

        /** Called when a port accepts a connection
         * Return MOD_RES_ACCEPT if you have used the file descriptor.
         * @param fd The file descriptor returned from accept()
         * @param sock The socket connection for the new user
         * @param client The client IP address and port
         * @param server The server IP address and port
         */
        virtual ModResult OnAcceptConnection(int fd, ListenSocket* sock, irc::sockets::sockaddrs* client, irc::sockets::sockaddrs* server);

        /** Called at intervals for modules to garbage-collect any hashes etc.
         * Certain data types such as hash_map 'leak' buckets, which must be
         * tidied up and freed by copying into a new item every so often. This
         * method is called when it is time to do that.
         */
        virtual void OnGarbageCollect();

        /** Called when a user's connect class is being matched
         * @return MOD_RES_ALLOW to force the class to match, MOD_RES_DENY to forbid it, or
         * MOD_RES_PASSTHRU to allow normal matching (by host/port).
         */
        virtual ModResult OnSetConnectClass(LocalUser* user, ConnectClass* myclass);

        virtual ModResult OnNumeric(User* user, const Numeric::Numeric& numeric);

        /** Called whenever a local user's IP is set for the first time, or when a local user's IP changes due to
         * a module like m_cgiirc changing it.
         * @param user The user whose IP is being set
         */
        virtual void OnSetUserIP(LocalUser* user);

        /** Called whenever a ServiceProvider is registered.
         * @param service ServiceProvider being registered.
         */
        virtual void OnServiceAdd(ServiceProvider& service);

        /** Called whenever a ServiceProvider is unregistered.
         * @param service ServiceProvider being unregistered.
         */
        virtual void OnServiceDel(ServiceProvider& service);

        /** Called whenever a message is about to be written to a user.
         * @param user The user who is having a message sent to them.
         * @param msg The message which is being written to the user.
         * @return MOD_RES_ALLOW to explicitly allow the message to be sent, MOD_RES_DENY to explicitly
         * deny the message from being sent, or MOD_RES_PASSTHRU to let another module handle the event.
         */
        virtual ModResult OnUserWrite(LocalUser* user, ClientProtocol::Message& msg);

        /** Called when a user connection has been unexpectedly disconnected.
         * @param user The user who has been unexpectedly disconnected.
         * @param error The type of error which caused this connection failure.
         * @return MOD_RES_ALLOW to explicitly retain the user as a zombie, MOD_RES_DENY to explicitly
         * disconnect the user, or MOD_RES_PASSTHRU to let another module handle the event.
         */
        virtual ModResult OnConnectionFail(LocalUser* user, BufferedSocketError error);

        /** Called before a server shuts down.
         * @param reason The reason the server is shutting down.
         * @param restart Whether the server is restarting.
         */
        virtual void OnShutdown(const std::string& reason);
};

/** ModuleManager takes care of all things module-related
 * in the core.
 */
class CoreExport ModuleManager : public fakederef<ModuleManager>
{
 public:
        typedef std::vector<ServiceProvider*> ServiceList;

 private:
        /** Holds a string describing the last module error to occur
         */
        std::string LastModuleError;

        /** List of loaded modules and shared object/dll handles
         * keyed by module name
         */
        std::map<std::string, Module*> Modules;

        enum {
                PRIO_STATE_FIRST,
                PRIO_STATE_AGAIN,
                PRIO_STATE_LAST
        } prioritizationState;

        /** Loads all core modules (core_*)
         */
        void LoadCoreModules(std::map<std::string, ServiceList>& servicemap);

        /** Calls the Prioritize() method in all loaded modules
         * @return True if all went well, false if a dependency loop was detected
         */
        bool PrioritizeHooks();

        /** Unregister all user modes or all channel modes owned by a module
         * @param mod Module whose modes to unregister
         * @param modetype MODETYPE_USER to unregister user modes, MODETYPE_CHANNEL to unregister channel modes
         */
        void UnregisterModes(Module* mod, ModeType modetype);

 public:
        typedef std::map<std::string, Module*> ModuleMap;

        /** Event handler hooks.
         * This needs to be public to be used by FOREACH_MOD and friends.
         */
        Module::List EventHandlers[I_END];

        /** List of data services keyed by name */
        std::multimap<std::string, ServiceProvider*, irc::insensitive_swo> DataProviders;

        /** A list of ServiceProviders waiting to be registered.
         * Non-NULL when constructing a Module, NULL otherwise.
         * When non-NULL ServiceProviders add themselves to this list on creation and the core
         * automatically registers them (that is, call AddService()) after the Module is constructed,
         * and before Module::init() is called.
         * If a service is created after the construction of the Module (for example in init()) it
         * has to be registered manually.
         */
        ServiceList* NewServices;

        /** Expands the name of a module by prepending "m_" and appending ".so".
         * No-op if the name already has the ".so" extension.
         * @param modname Module name to expand
         * @return Module name starting with "m_" and ending with ".so"
         */
        static std::string ExpandModName(const std::string& modname);

        /** Simple, bog-standard, boring constructor.
         */
        ModuleManager();

        /** Destructor
         */
        ~ModuleManager();

        /** Change the priority of one event in a module.
         * Each module event has a list of modules which are attached to that event type.
         * If you wish to be called before or after other specific modules, you may use this
         * method (usually within void Module::Prioritize()) to set your events priority.
         * You may use this call in other methods too, however, this is not supported behaviour
         * for a module.
         * @param mod The module to change the priority of
         * @param i The event to change the priority of
         * @param s The state you wish to use for this event. Use one of
         * PRIO_FIRST to set the event to be first called, PRIO_LAST to
         * set it to be the last called, or PRIO_BEFORE and PRIORITY_AFTER
         * to set it to be before or after one or more other modules.
         * @param which If PRIO_BEFORE or PRIORITY_AFTER is set in parameter 's',
         * then this contains a the module that your module must be placed before
         * or after.
         */
        bool SetPriority(Module* mod, Implementation i, Priority s, Module* which = NULL);

        /** Change the priority of all events in a module.
         * @param mod The module to set the priority of
         * @param s The priority of all events in the module.
         * Note that with this method, it is not possible to effectively use
         * PRIO_BEFORE or PRIORITY_AFTER, you should use the more fine tuned
         * SetPriority method for this, where you may specify other modules to
         * be prioritized against.
         */
        void SetPriority(Module* mod, Priority s);

        /** Attach an event to a module.
         * You may later detatch the event with ModuleManager::Detach().
         * If your module is unloaded, all events are automatically detatched.
         * @param i Event type to attach
         * @param mod Module to attach event to
         * @return True if the event was attached
         */
        bool Attach(Implementation i, Module* mod);

        /** Detatch an event from a module.
         * This is not required when your module unloads, as the core will
         * automatically detatch your module from all events it is attached to.
         * @param i Event type to detach
         * @param mod Module to detach event from
         * @return True if the event was detached
         */
        bool Detach(Implementation i, Module* mod);

        /** Attach an array of events to a module
         * @param i Event types (array) to attach
         * @param mod Module to attach events to
         * @param sz The size of the implementation array
         */
        void Attach(Implementation* i, Module* mod, size_t sz);

        /** Detach all events from a module (used on unload)
         * @param mod Module to detach from
         */
        void DetachAll(Module* mod);

        /** Attach all events to a module (used on module load)
         * @param mod Module to attach to all events
         */
        void AttachAll(Module* mod);

        /** Returns text describing the last module error
         * @return The last error message to occur
         */
        std::string& LastError();

        /** Load a given module file
         * @param filename The file to load
         * @param defer Defer module init (loading many modules)
         * @return True if the module was found and loaded
         */
        bool Load(const std::string& filename, bool defer = false);

        /** Unload a given module file. Note that the module will not be
         * completely gone until the cull list has finished processing.
         *
         * @return true on success; if false, LastError will give a reason
         */
        bool Unload(Module* module);

        /** Called by the InspIRCd constructor to load all modules from the config file.
         */
        void LoadAll();
        void UnloadAll();
        void DoSafeUnload(Module*);

        /** Check if a module can be unloaded and if yes, prepare it for unload
         * @param mod Module to be unloaded
         * @return True if the module is unloadable, false otherwise.
         * If true the module must be unloaded in the current main loop iteration.
         */
        bool CanUnload(Module* mod);

        /** Find a module by name, and return a Module* to it.
         * This is preferred over iterating the module lists yourself.
         * @param name The module name to look up
         * @return A pointer to the module, or NULL if the module cannot be found
         */
        Module* Find(const std::string &name);

        /** Register a service provided by a module */
        void AddService(ServiceProvider&);

        /** Unregister a service provided by a module */
        void DelService(ServiceProvider&);

        /** Register all services in a given ServiceList
         * @param list The list containing the services to register
         */
        void AddServices(const ServiceList& list);

        inline void AddServices(ServiceProvider** list, int count)
        {
                for(int i=0; i < count; i++)
                        AddService(*list[i]);
        }

        /** Find a service by name.
         * If multiple modules provide a given service, the first one loaded will be chosen.
         */
        ServiceProvider* FindService(ServiceType Type, const std::string& name);

        template<typename T> inline T* FindDataService(const std::string& name)
        {
                return static_cast<T*>(FindService(SERVICE_DATA, name));
        }

        /** Get a map of all loaded modules keyed by their name
         * @return A ModuleMap containing all loaded modules
         */
        const ModuleMap& GetModules() const { return Modules; }

        /** Make a service referenceable by dynamic_references
         * @param name Name that will be used by dynamic_references to find the object
         * @param service Service to make referenceable by dynamic_references
         */
        void AddReferent(const std::string& name, ServiceProvider* service);

        /** Make a service no longer referenceable by dynamic_references
         * @param service Service to make no longer referenceable by dynamic_references
         */
        void DelReferent(ServiceProvider* service);
};