/*
* InspIRCd -- Internet Relay Chat Daemon
*
* Copyright (C) 2021 Dominic Hamon
* Copyright (C) 2020-2023 Sadie Powell <sadie@witchery.services>
* Copyright (C) 2018 linuxdaemon <linuxdaemon.irc@gmail.com>
* Copyright (C) 2014 Adam <Adam@anope.org>
* Copyright (C) 2013-2014, 2016 Attila Molnar <attilamolnar@hush.com>
* Copyright (C) 2013 Daniel Vassdal <shutter@canternet.org>
* Copyright (C) 2012, 2019 Robby <robby@chatbelgie.be>
* Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org>
* Copyright (C) 2009 Matt Smith <dz@inspircd.org>
* Copyright (C) 2008 Uli Schlachter <psychon@znc.in>
* Copyright (C) 2008 Craig Edwards <brain@inspircd.org>
* Copyright (C) 2007-2009 Robin Burchell <robin+git@viroteck.net>
* 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/>.
*/
#include "inspircd.h"
#include "listmode.h"
#include "modules/extban.h"
/* Originally written by Om, January 2009
*/
class BanRedirectEntry final
{
public:
std::string targetchan;
std::string banmask;
BanRedirectEntry(const std::string& target = "", const std::string& mask = "")
: targetchan(target)
, banmask(mask)
{
}
};
typedef std::vector<BanRedirectEntry> BanRedirectList;
class BanRedirect final
: public ModeWatcher
{
public:
ChanModeReference banmode;
ExtBan::ManagerRef extbanmgr;
SimpleExtItem<BanRedirectList> redirectlist;
BanRedirect(Module* parent)
: ModeWatcher(parent, "ban", MODETYPE_CHANNEL)
, banmode(parent, "ban")
, extbanmgr(parent)
, redirectlist(parent, "banredirect", ExtensionType::CHANNEL)
{
}
bool BeforeMode(User* source, User* dest, Channel* channel, Modes::Change& change) override
{
/* nick!user@host -> nick!user@host
* nick!user@host#chan -> nick!user@host#chan
* nick@host#chan -> nick!*@host#chan
* nick!user#chan -> nick!user@*#chan
* nick#chan -> nick!*@*#chan
*/
if ((channel) && !change.param.empty())
{
BanRedirectList* redirects;
std::string mask[4];
enum { NICK, USER, HOST, CHAN } current = NICK;
std::string::iterator start_pos = change.param.begin();
std::string unused = change.param;
if (extbanmgr && extbanmgr->Canonicalize(unused))
return true; // Skip extbans.
if (change.param.find('#') == std::string::npos)
return true;
ListModeBase* banlm = static_cast<ListModeBase*>(*banmode);
unsigned long maxbans = banlm->GetLimit(channel);
ListModeBase::ModeList* list = banlm->GetList(channel);
if (list && change.adding && maxbans <= list->size())
{
source->WriteNumeric(ERR_BANLISTFULL, channel->name, banlm->GetModeChar(), FMT::format("Channel ban list for {} is full (maximum entries for this channel is {})",
channel->name, maxbans));
return false;
}
for(std::string::iterator curr = start_pos; curr != change.param.end(); curr++)
{
switch(*curr)
{
case '!':
if (current != NICK)
break;
mask[current].assign(start_pos, curr);
current = USER;
start_pos = curr+1;
break;
case '@':
if (current != USER)
break;
mask[current].assign(start_pos, curr);
current = HOST;
start_pos = curr+1;
break;
case '#':
if (current == CHAN)
break;
mask[current].assign(start_pos, curr);
current = CHAN;
start_pos = curr;
break;
}
}
if(mask[current].empty())
{
mask[current].assign(start_pos, change.param.end());
}
/* nick@host wants to be changed to *!nick@host rather than nick!*@host... */
if(mask[NICK].length() && mask[HOST].length() && mask[USER].empty())
{
/* std::string::swap() is fast - it runs in constant time */
mask[NICK].swap(mask[USER]);
}
if (!mask[NICK].empty() && mask[USER].empty() && mask[HOST].empty())
{
if (mask[NICK].find('.') != std::string::npos || mask[NICK].find(':') != std::string::npos)
{
mask[NICK].swap(mask[HOST]);
}
}
for(int i = 0; i < 3; i++)
{
if(mask[i].empty())
{
mask[i].assign("*");
}
}
change.param.assign(mask[NICK]).append(1, '!').append(mask[USER]).append(1, '@').append(mask[HOST]);
if(mask[CHAN].length())
{
if (change.adding && IS_LOCAL(source))
{
if (!ServerInstance->Channels.IsChannel(mask[CHAN]))
{
source->WriteNumeric(ERR_NOSUCHCHANNEL, channel->name, FMT::format("Invalid channel name in redirection ({})", mask[CHAN]));
return false;
}
auto* c = ServerInstance->Channels.Find(mask[CHAN]);
if (!c)
{
source->WriteNumeric(690, FMT::format("Target channel {} must exist to be set as a redirect.", mask[CHAN]));
return false;
}
else if (change.adding && c->GetPrefixValue(source) < OP_VALUE)
{
source->WriteNumeric(690, FMT::format("You must be opped on {} to set it as a redirect.", mask[CHAN]));
return false;
}
if (irc::equals(channel->name, mask[CHAN]))
{
source->WriteNumeric(690, channel->name, "You cannot set a ban redirection to the channel the ban is on");
return false;
}
}
if (change.adding)
{
/* It's a properly valid redirecting ban, and we're adding it */
redirects = redirectlist.Get(channel);
if (!redirects)
{
redirects = new BanRedirectList;
redirectlist.Set(channel, redirects);
}
else
{
for (const auto& redirect : *redirects)
{
// Mimic the functionality used when removing the mode
if (irc::equals(redirect.targetchan, mask[CHAN]) && irc::equals(redirect.banmask, change.param))
{
// Make sure the +b handler will still set the right ban
change.param.append(mask[CHAN]);
// Silently ignore the duplicate and don't set metadata
// This still allows channel ops to set/unset a redirect ban to clear "ghost" redirects
return true;
}
}
}
/* Here 'param' doesn't have the channel on it yet */
redirects->emplace_back(mask[CHAN], change.param);
/* Now it does */
change.param.append(mask[CHAN]);
}
else
{
/* Removing a ban, if there's no extensible there are no redirecting bans and we're fine. */
redirects = redirectlist.Get(channel);
if (redirects)
{
/* But there were, so we need to remove the matching one if there is one */
for(BanRedirectList::iterator redir = redirects->begin(); redir != redirects->end(); redir++)
{
if ((irc::equals(redir->targetchan, mask[CHAN])) && (irc::equals(redir->banmask, change.param)))
{
redirects->erase(redir);
if(redirects->empty())
{
redirectlist.Unset(channel);
}
break;
}
}
}
/* Append the channel so the default +b handler can remove the entry too */
change.param.append(mask[CHAN]);
}
}
}
return true;
}
};
class ModuleBanRedirect final
: public Module
{
private:
BanRedirect banwatcher;
bool nofollow = false;
ChanModeReference limitmode;
ChanModeReference redirectmode;
public:
ModuleBanRedirect()
: Module(VF_VENDOR | VF_COMMON, "Allows specifying a channel to redirect a banned user to in the ban mask.")
, banwatcher(this)
, limitmode(this, "limit")
, redirectmode(this, "redirect")
{
}
void OnCleanup(ExtensionType type, Extensible* item) override
{
if (type != ExtensionType::CHANNEL)
return;
auto* chan = static_cast<Channel*>(item);
auto* redirects = banwatcher.redirectlist.Get(chan);
if (!redirects)
return;
Modes::ChangeList changelist;
for (auto& redirect : *redirects)
changelist.push_remove(*banwatcher.banmode, redirect.targetchan.insert(0, redirect.banmask));
for (const auto& redirect : *redirects)
changelist.push_add(*banwatcher.banmode, redirect.banmask);
ServerInstance->Modes.Process(ServerInstance->FakeClient, chan, nullptr, changelist, ModeParser::MODE_LOCALONLY);
}
ModResult OnUserPreJoin(LocalUser* user, Channel* chan, const std::string& cname, std::string& privs, const std::string& keygiven, bool override) override
{
if (!override && chan)
{
BanRedirectList* redirects = banwatcher.redirectlist.Get(chan);
if (redirects)
{
/* We actually had some ban redirects to check */
ModResult result;
FIRST_MOD_RESULT(OnCheckChannelBan, result, (user, chan, ServerInstance->Config->BanRealMask));
if (result == MOD_RES_ALLOW)
{
// they have a ban exception
return MOD_RES_PASSTHRU;
}
std::string ipmask(user->nick);
ipmask.append(1, '!').append(user->GetUserAddress());
for (const auto& redirect : *redirects)
{
if (InspIRCd::Match(user->GetRealMask(), redirect.banmask) || InspIRCd::Match(user->GetMask(), redirect.banmask) || InspIRCd::MatchCIDR(ipmask, redirect.banmask))
{
/* This prevents recursion when a user sets multiple ban redirects in a chain
* (thanks Potter)
*
* If we're here and nofollow is true then we're already redirecting this user
* and there's a redirecting ban set on this channel that matches him, too.
* Deny both joins.
*/
if (nofollow)
return MOD_RES_DENY;
/* tell them they're banned and are being transferred */
auto* destchan = ServerInstance->Channels.Find(redirect.targetchan);
std::string destlimit;
if (destchan)
destlimit = destchan->GetModeParameter(limitmode);
if(destchan && destchan->IsModeSet(redirectmode) && !destlimit.empty() && (destchan->GetUsers().size() >= ConvToNum<size_t>(destlimit)))
{
user->WriteNumeric(ERR_BANNEDFROMCHAN, chan->name, "Cannot join channel (you're banned)");
return MOD_RES_DENY;
}
else
{
user->WriteNumeric(ERR_BANNEDFROMCHAN, chan->name, "Cannot join channel (you're banned)");
user->WriteNumeric(470, chan->name, redirect.targetchan, "You are banned from this channel, so you are automatically being transferred to the redirected channel.");
nofollow = true;
Channel::JoinUser(user, redirect.targetchan);
nofollow = false;
return MOD_RES_DENY;
}
}
}
}
}
return MOD_RES_PASSTHRU;
}
};
MODULE_INIT(ModuleBanRedirect)
