Add a module for hiding mode changes from unprivileged users.

Co-authored-by: Attila Molnar <attilamolnar@hush.com>

2 files changed, 206 insertions, 0 deletions

diff --git a/docs/conf/modules.conf.example b/docs/conf/modules.conf.example
index 9cc40bdd7..bc90c7b14 100644
--- a/docs/conf/modules.conf.example
+++ b/docs/conf/modules.conf.example
@@ -906,6 +906,14 @@
 #<hidelist mode="invex" rank="0">
 
 #-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
+# Hide mode module: Allows for hiding mode changes from users who do not
+# have sufficient channel privileges.
+#<module name="hidemode">
+#
+# Hide bans (+b) from people who are not voiced:
+#<hidemode mode="ban" rank="10000">
+
+#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
 # Hide oper module: Allows opers to hide their oper status from non-
 # opers by setting user mode +H on themselves.
 # This module is oper-only.
diff --git a/src/modules/m_hidemode.cpp b/src/modules/m_hidemode.cpp
new file mode 100644
index 000000000..d6ae05801
--- /dev/null
+++ b/src/modules/m_hidemode.cpp
@@ -0,0 +1,198 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2016 Attila Molnar <attilamolnar@hush.com>
+ *
+ * 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"
+
+namespace
+{
+class Settings
+{
+	typedef insp::flat_map<std::string, unsigned int> RanksToSeeMap;
+	RanksToSeeMap rankstosee;
+
+ public:
+	unsigned int GetRequiredRank(const ModeHandler& mh) const
+	{
+		RanksToSeeMap::const_iterator it = rankstosee.find(mh.name);
+		if (it != rankstosee.end())
+			return it->second;
+		return 0;
+	}
+
+	void Load()
+	{
+		rankstosee.clear();
+
+		ConfigTagList tags = ServerInstance->Config->ConfTags("hidemode");
+		for (ConfigIter i = tags.first; i != tags.second; ++i)
+		{
+			ConfigTag* tag = i->second;
+			std::string modename = tag->getString("mode");
+			unsigned int rank = tag->getInt("rank", 0, 0);
+			if (!modename.empty() && rank)
+			{
+				ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Hiding the %s mode from users below rank %u", modename.c_str(), rank);
+				rankstosee.insert(std::make_pair(modename, rank));
+			}
+		}
+	}
+};
+
+class ModeHook : public ClientProtocol::EventHook
+{
+	typedef insp::flat_map<unsigned int, const ClientProtocol::MessageList*> FilteredModeMap;
+
+	std::vector<Modes::ChangeList> modechangelists;
+	std::list<ClientProtocol::Messages::Mode> filteredmodelist;
+	std::list<ClientProtocol::MessageList> filteredmsgplists;
+	FilteredModeMap cache;
+
+	static ModResult HandleResult(const ClientProtocol::MessageList* filteredmessagelist, ClientProtocol::MessageList& messagelist)
+	{
+		// Deny if member isn't allowed to see even a single mode change from this mode event
+		if (!filteredmessagelist)
+			return MOD_RES_DENY;
+
+		// Member is allowed to see at least one mode change, replace list
+		if (filteredmessagelist != &messagelist)
+			messagelist = *filteredmessagelist;
+
+		return MOD_RES_PASSTHRU;
+	}
+
+	Modes::ChangeList* FilterModeChangeList(const ClientProtocol::Events::Mode& mode, unsigned int rank)
+	{
+		Modes::ChangeList* modechangelist = NULL;
+		for (Modes::ChangeList::List::const_iterator i = mode.GetChangeList().getlist().begin(); i != mode.GetChangeList().getlist().end(); ++i)
+		{
+			const Modes::Change& curr = *i;
+			if (settings.GetRequiredRank(*curr.mh) <= rank)
+			{
+				 // No restriction on who can see this mode or there is one but the member's rank is sufficient
+				if (modechangelist)
+					modechangelist->push(curr);
+
+				continue;
+			}
+
+			// Member cannot see the current mode change
+
+			if (!modechangelist)
+			{
+				// Create new mode change list or reuse the last one if it's empty
+				if ((modechangelists.empty()) || (!modechangelists.back().empty()))
+					modechangelists.push_back(Modes::ChangeList());
+
+				// Add all modes to it which we've accepted so far
+				modechangelists.back().push(mode.GetChangeList().getlist().begin(), i);
+				modechangelist = &modechangelists.back();
+			}
+		}
+		return modechangelist;
+	}
+
+	void OnEventInit(const ClientProtocol::Event& ev) CXX11_OVERRIDE
+	{
+		cache.clear();
+		filteredmsgplists.clear();
+		filteredmodelist.clear();
+		modechangelists.clear();
+
+		// Ensure no reallocations will happen
+		const size_t numprefixmodes = ServerInstance->Modes.GetPrefixModes().size();
+		modechangelists.reserve(numprefixmodes);
+	}
+
+	ModResult OnPreEventSend(LocalUser* user, const ClientProtocol::Event& ev, ClientProtocol::MessageList& messagelist) CXX11_OVERRIDE
+	{
+		const ClientProtocol::Events::Mode& mode = static_cast<const ClientProtocol::Events::Mode&>(ev);
+		Channel* const chan = mode.GetMessages().front().GetChanTarget();
+		if (!chan)
+			return MOD_RES_PASSTHRU;
+
+		Membership* const memb = chan->GetUser(user);
+		if (!memb)
+			return MOD_RES_PASSTHRU;
+
+		// Check cache first
+		const FilteredModeMap::const_iterator it = cache.find(memb->getRank());
+		if (it != cache.end())
+			return HandleResult(it->second, messagelist);
+
+		// Message for this rank isn't cached, generate it now
+		const Modes::ChangeList* const filteredchangelist = FilterModeChangeList(mode, memb->getRank());
+
+		// If no new change list was generated (above method returned NULL) it means the member and everyone else
+		// with the same rank can see everything in the original change list.
+		ClientProtocol::MessageList* finalmsgplist = &messagelist;
+		if (filteredchangelist)
+		{
+			if (filteredchangelist->empty())
+			{
+				// This rank cannot see any mode changes in the original change list
+				finalmsgplist = NULL;
+			}
+			else
+			{
+				// This rank can see some of the mode changes in the filtered mode change list.
+				// Create and store a new protocol message from it.
+				filteredmsgplists.push_back(ClientProtocol::MessageList());
+				ClientProtocol::Events::Mode::BuildMessages(mode.GetMessages().front().GetSourceUser(), chan, NULL, *filteredchangelist, filteredmodelist, filteredmsgplists.back());
+				finalmsgplist = &filteredmsgplists.back();
+			}
+		}
+
+		// Cache the result in all cases so it can be reused for further members with the same rank
+		cache.insert(std::make_pair(memb->getRank(), finalmsgplist));
+		return HandleResult(finalmsgplist, messagelist);
+	}
+
+ public:
+	Settings settings;
+
+	ModeHook(Module* mod)
+		: ClientProtocol::EventHook(mod, "MODE", 10)
+	{
+	}
+};
+}
+
+class ModuleHideMode : public Module
+{
+ private:
+	ModeHook modehook;
+
+ public:
+	ModuleHideMode()
+		: modehook(this)
+	{
+	}
+
+	void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
+	{
+		modehook.settings.Load();
+	}
+
+	Version GetVersion() CXX11_OVERRIDE
+	{
+		return Version("Provides support for hiding mode changes", VF_VENDOR);
+	}
+};
+
+MODULE_INIT(ModuleHideMode)