Shuffle the modules about a bit.

1 files changed, 332 insertions, 0 deletions

diff --git a/modules/spanningtree/fjoin.cpp b/modules/spanningtree/fjoin.cpp
new file mode 100644
index 000000000..d2329c76b
--- /dev/null
+++ b/modules/spanningtree/fjoin.cpp
@@ -0,0 +1,332 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2018-2023 Sadie Powell <sadie@witchery.services>
+ *   Copyright (C) 2012-2016 Attila Molnar <attilamolnar@hush.com>
+ *   Copyright (C) 2012 Robby <robby@chatbelgie.be>
+ *   Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org>
+ *   Copyright (C) 2008, 2012 Robin Burchell <robin+git@viroteck.net>
+ *   Copyright (C) 2008 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 "timeutils.h"
+
+#include "commands.h"
+#include "treeserver.h"
+#include "treesocket.h"
+
+/** FJOIN builder for rebuilding incoming FJOINs and splitting them up into multiple messages if necessary
+ */
+class FwdFJoinBuilder final
+	: public CommandFJoin::Builder
+{
+public:
+	FwdFJoinBuilder(Channel* chan, TreeServer* server)
+		: CommandFJoin::Builder(chan, server)
+	{
+	}
+
+	void add(Membership* memb, std::string::const_iterator mbegin, std::string::const_iterator mend);
+};
+
+/** FJOIN, almost identical to TS6 SJOIN, except for nicklist handling. */
+CmdResult CommandFJoin::Handle(User* srcuser, Params& params)
+{
+	/* 1.1+ FJOIN works as follows:
+	 *
+	 * Each FJOIN is sent along with a timestamp, and the side with the lowest
+	 * timestamp 'wins'. From this point on we will refer to this side as the
+	 * winner. The side with the higher timestamp loses, from this point on we
+	 * will call this side the loser or losing side. This should be familiar to
+	 * anyone who's dealt with dreamforge or TS6 before.
+	 *
+	 * When two sides of a split heal and this occurs, the following things
+	 * will happen:
+	 *
+	 * If the timestamps are exactly equal, both sides merge their privileges
+	 * and users, as in InspIRCd 1.0 and ircd2.8. The channels have not been
+	 * re-created during a split, this is safe to do.
+	 *
+	 * If the timestamps are NOT equal, the losing side removes all of its
+	 * modes from the channel, before introducing new users into the channel
+	 * which are listed in the FJOIN command's parameters. The losing side then
+	 * LOWERS its timestamp value of the channel to match that of the winning
+	 * side, and the modes of the users of the winning side are merged in with
+	 * the losing side.
+	 *
+	 * The winning side on the other hand will ignore all user modes from the
+	 * losing side, so only its own modes get applied. Life is simple for those
+	 * who succeed at internets. :-)
+	 *
+	 * Outside of netbursts, the winning side also resyncs the losing side if it
+	 * detects that the other side recreated the channel.
+	 *
+	 * Syntax:
+	 * :<sid> FJOIN <chan> <TS> <modes> :[<member> [<member> ...]]
+	 * The last parameter is a list consisting of zero or more channel members
+	 * (permanent channels may have zero users). Each entry on the list is in the
+	 * following format:
+	 * [[<modes>,]<uuid>[:<membid>]
+	 * <modes> is a concatenation of the mode letters the user has on the channel
+	 * (e.g.: "ov" if the user is opped and voiced). The order of the mode letters
+	 * are not important but if a server encounters an unknown mode letter, it will
+	 * drop the link to avoid desync.
+	 *
+	 * InspIRCd 2.0 and older required a comma before the uuid even if the user
+	 * had no prefix modes on the channel, InspIRCd 3.0 and later does not require
+	 * a comma in this case anymore.
+	 *
+	 * <membid> is a positive integer representing the id of the membership.
+	 * If not present (in FJOINs coming from pre-1205 servers), 0 is assumed.
+	 *
+	 * Forwarding:
+	 * FJOIN messages are forwarded with the new TS and modes. Prefix modes of
+	 * members on the losing side are not forwarded.
+	 * This is required to only have one server on each side of the network who
+	 * decides the fate of a channel during a network merge. Otherwise, if the
+	 * clock of a server is slightly off it may make a different decision than
+	 * the rest of the network and desync.
+	 * The prefix modes are always forwarded as-is, or not at all.
+	 *
+	 * Forwarding examples:
+	 * Existing channel #chan with TS 1000, modes +n.
+	 * Incoming:  :220 FJOIN #chan 1000 +t :o,220AAAAAB:0
+	 * Forwarded: :220 FJOIN #chan 1000 +nt :o,220AAAAAB:0
+	 * Merge modes and forward the result. Forward their prefix modes as well.
+	 *
+	 * Existing channel #chan with TS 1000, modes +nt.
+	 * Incoming:  :220 FJOIN #CHAN 2000 +i :ov,220AAAAAB:0 o,220AAAAAC:20
+	 * Forwarded: :220 FJOIN #chan 1000 +nt :,220AAAAAB:0 ,220AAAAAC:20
+	 * Drop their modes, forward our modes and TS, use our channel name
+	 * capitalization. Don't forward prefix modes.
+	 *
+	 */
+
+	time_t TS = ServerCommand::ExtractTS(params[1]);
+
+	const std::string& channel = params[0];
+	auto* chan = ServerInstance->Channels.Find(channel);
+	bool apply_other_sides_modes = true;
+	TreeServer* const sourceserver = TreeServer::Get(srcuser);
+
+	if (!chan)
+	{
+		if (!ServerInstance->Channels.IsPrefix(channel[0]))
+			throw ProtocolException("Malformed channel name in FJOIN: " + channel);
+
+		chan = new Channel(channel, TS);
+	}
+	else
+	{
+		time_t ourTS = chan->age;
+		if (TS != ourTS)
+		{
+			ServerInstance->Logs.Debug(MODNAME, "Merge FJOIN received for {}, ourTS: {}, TS: {}, difference: {}",
+				chan->name, ourTS, TS, ourTS - TS);
+			/* If our TS is less than theirs, we dont accept their modes */
+			if (ourTS < TS)
+			{
+				// If the source server isn't bursting then this FJOIN is the result of them recreating the channel with a higher TS.
+				// This happens if the last user on the channel hops and before the PART propagates a user on another server joins. Fix it by doing a resync.
+				// Servers behind us won't react this way because the forwarded FJOIN will have the correct TS.
+				if (!sourceserver->IsBursting())
+				{
+					ServerInstance->Logs.Debug(MODNAME, "Server {} recreated channel {} with higher TS, resyncing", sourceserver->GetName(), chan->name);
+					sourceserver->GetSocket()->SyncChannel(chan);
+				}
+				apply_other_sides_modes = false;
+			}
+			else if (ourTS > TS)
+			{
+				// Our TS is greater than theirs, remove all modes, extensions, etc. from the channel
+				LowerTS(chan, TS, channel);
+
+				// XXX: If the channel does not exist in the chan hash at this point, create it so the remote modes can be applied on it.
+				// This happens to 0-user permanent channels on the losing side, because those are removed (from the chan hash, then
+				// deleted later) as soon as the permchan mode is removed from them.
+				if (!ServerInstance->Channels.Find(channel))
+				{
+					chan = new Channel(channel, TS);
+				}
+			}
+		}
+	}
+
+	// Apply their channel modes if we have to
+	Modes::ChangeList modechangelist;
+	if (apply_other_sides_modes)
+	{
+		ServerInstance->Modes.ModeParamsToChangeList(srcuser, MODETYPE_CHANNEL, params, modechangelist, 2, params.size() - 1);
+		ServerInstance->Modes.Process(srcuser, chan, nullptr, modechangelist, ModeParser::MODE_LOCALONLY | ModeParser::MODE_MERGE);
+		// Reuse for prefix modes
+		modechangelist.clear();
+	}
+
+	// Build a new FJOIN for forwarding. Put the correct TS in it and the current modes of the channel
+	// after applying theirs. If they lost, the prefix modes from their message are not forwarded.
+	FwdFJoinBuilder fwdfjoin(chan, sourceserver);
+
+	// Process every member in the message
+	irc::spacesepstream users(params.back());
+	std::string item;
+	Modes::ChangeList* modechangelistptr = (apply_other_sides_modes ? &modechangelist : nullptr);
+	while (users.GetToken(item))
+	{
+		ProcessModeUUIDPair(item, sourceserver, chan, modechangelistptr, fwdfjoin);
+	}
+
+	fwdfjoin.finalize();
+	fwdfjoin.Forward(sourceserver->GetRoute());
+
+	// Set prefix modes on their users if we lost the FJOIN or had equal TS
+	if (apply_other_sides_modes)
+		ServerInstance->Modes.Process(srcuser, chan, nullptr, modechangelist, ModeParser::MODE_LOCALONLY);
+
+	return CmdResult::SUCCESS;
+}
+
+void CommandFJoin::ProcessModeUUIDPair(const std::string& item, TreeServer* sourceserver, Channel* chan, Modes::ChangeList* modechangelist, FwdFJoinBuilder& fwdfjoin)
+{
+	std::string::size_type comma = item.find(',');
+
+	// Comma not required anymore if the user has no modes
+	const std::string::size_type ubegin = (comma == std::string::npos ? 0 : comma+1);
+	std::string uuid(item, ubegin, UIDGenerator::UUID_LENGTH);
+	auto* who = ServerInstance->Users.FindUUID(uuid);
+	if (!who)
+	{
+		// Probably KILLed, ignore
+		return;
+	}
+
+	TreeSocket* src_socket = sourceserver->GetSocket();
+	/* Check that the user's 'direction' is correct */
+	TreeServer* route_back_again = TreeServer::Get(who);
+	if (route_back_again->GetSocket() != src_socket)
+	{
+		return;
+	}
+
+	std::string::const_iterator modeendit = item.begin(); // End of the "ov" mode string
+	/* Check if the user received at least one mode */
+	if ((modechangelist) && (comma != std::string::npos))
+	{
+		modeendit += comma;
+		/* Iterate through the modes and see if they are valid here, if so, apply */
+		for (std::string::const_iterator i = item.begin(); i != modeendit; ++i)
+		{
+			ModeHandler* mh = ServerInstance->Modes.FindMode(*i, MODETYPE_CHANNEL);
+			if (!mh)
+				throw ProtocolException("Unrecognised mode '" + std::string(1, *i) + "'");
+
+			/* Add any modes this user had to the mode stack */
+			modechangelist->push_add(mh, who->nick);
+		}
+	}
+
+	Membership* memb = chan->ForceJoin(who, nullptr, sourceserver->IsBursting());
+	if (!memb)
+	{
+		// User was already on the channel, forward because of the modes they potentially got
+		memb = chan->GetUser(who);
+		if (memb)
+			fwdfjoin.add(memb, item.begin(), modeendit);
+		return;
+	}
+
+	// Assign the id to the new Membership
+	Membership::Id membid = 0;
+	const std::string::size_type colon = item.rfind(':');
+	if (colon != std::string::npos)
+		membid = Membership::IdFromString(item.substr(colon+1));
+	memb->id = membid;
+
+	// Add member to fwdfjoin with prefix modes
+	fwdfjoin.add(memb, item.begin(), modeendit);
+}
+
+void CommandFJoin::RemoveStatus(Channel* c)
+{
+	Modes::ChangeList changelist;
+
+	for (const auto& [_, mh] : ServerInstance->Modes.GetModes(MODETYPE_CHANNEL))
+	{
+		// Add the removal of this mode to the changelist. This handles all kinds of modes, including prefix modes.
+		mh->RemoveMode(c, changelist);
+	}
+
+	ServerInstance->Modes.Process(ServerInstance->FakeClient, c, nullptr, changelist, ModeParser::MODE_LOCALONLY);
+}
+
+void CommandFJoin::LowerTS(Channel* chan, time_t TS, const std::string& newname)
+{
+	if (Utils->AnnounceTSChange)
+	{
+		// WriteRemoteNotice is not used here because the message only needs to go to the local server.
+		chan->WriteNotice(fmt::format("Creation time of {} changed from {} to {}", newname,
+			Time::ToString(chan->age), Time::ToString(TS)));
+	}
+
+	// While the name is equal in case-insensitive compare, it might differ in case; use the remote version
+	chan->name = newname;
+	chan->age = TS;
+
+	// Clear all modes
+	CommandFJoin::RemoveStatus(chan);
+
+	// Unset all extensions
+	chan->FreeAllExtItems();
+
+	// Clear the topic
+	chan->SetTopic(ServerInstance->FakeClient, std::string(), 0);
+	chan->setby.clear();
+}
+
+CommandFJoin::Builder::Builder(Channel* chan, TreeServer* source)
+	: CmdBuilder(source, "FJOIN")
+{
+	push(chan->name).push_int(chan->age).push_raw(" +");
+	pos = str().size();
+	push_raw(chan->ChanModes(true)).push_raw(" :");
+}
+
+void CommandFJoin::Builder::add(Membership* memb, std::string::const_iterator mbegin, std::string::const_iterator mend)
+{
+	push_raw(mbegin, mend).push_raw(',').push_raw(memb->user->uuid);
+	push_raw(':').push_raw_int(memb->id);
+	push_raw(' ');
+}
+
+void CommandFJoin::Builder::clear()
+{
+	content.erase(pos);
+	push_raw(" :");
+}
+
+const std::string& CommandFJoin::Builder::finalize()
+{
+	if (content.back() == ' ')
+		content.pop_back();
+	return str();
+}
+
+void FwdFJoinBuilder::add(Membership* memb, std::string::const_iterator mbegin, std::string::const_iterator mend)
+{
+	// Add the member and their modes exactly as they sent them
+	CommandFJoin::Builder::add(memb, mbegin, mend);
+}