Implement support for the IRCv3 labeled-response specification.

2 files changed, 248 insertions, 0 deletions

diff --git a/docs/conf/modules.conf.example b/docs/conf/modules.conf.example
index 29adff840..d68248163 100644
--- a/docs/conf/modules.conf.example
+++ b/docs/conf/modules.conf.example
@@ -1195,6 +1195,12 @@
 #<module name="ircv3_invitenotify">
 
 #-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
+# IRCv3 labeled-response module: Provides the labeled-response IRCv3
+# extension which allows server responses to be associated with the
+# client message which caused them to be sent.
+#<module name="ircv3_labeledresponse">
+
+#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#
 # IRCv3 message id module: Provides the msgid IRCv3 extension which
 # adds a unique identifier to each message when the message-tags cap
 # has been requested. This enables support for modern features such as
diff --git a/src/modules/m_ircv3_labeledresponse.cpp b/src/modules/m_ircv3_labeledresponse.cpp
new file mode 100644
index 000000000..a0803c18d
--- /dev/null
+++ b/src/modules/m_ircv3_labeledresponse.cpp
@@ -0,0 +1,242 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2016 Attila Molnar <attilamolnar@hush.com>
+ *   Copyright (C) 2018-2020 Sadie Powell <sadie@witchery.services>
+ *
+ * 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 "modules/cap.h"
+#include "modules/ircv3_batch.h"
+
+class LabeledResponseTag : public ClientProtocol::MessageTagProvider
+{
+ private:
+	const Cap::Capability& cap;
+
+ public:
+	LocalUser* labeluser;
+	std::string label;
+	const std::string labeltag;
+
+	LabeledResponseTag(Module* mod, const Cap::Capability& capref)
+		: ClientProtocol::MessageTagProvider(mod)
+		, cap(capref)
+		, labeluser(NULL)
+		, labeltag("label")
+	{
+	}
+
+	ModResult OnProcessTag(User* user, const std::string& tagname, std::string& tagvalue) CXX11_OVERRIDE
+	{
+		if (!irc::equals(tagname, labeltag))
+			return MOD_RES_PASSTHRU;
+
+		// If the tag is empty or too long then we can't accept it.
+		if (tagvalue.empty() || tagvalue.size() > 64)
+			return MOD_RES_DENY;
+
+		// If the user is local then we check whether they have the labeled-response
+		// cap enabled. If not then we reject the label tag originating from them.
+		LocalUser* lu = IS_LOCAL(user);
+		if (lu && !cap.get(lu))
+			return MOD_RES_DENY;
+
+		// Remote users have their label tag checked by their local server.
+		return MOD_RES_ALLOW;
+	}
+
+	bool ShouldSendTag(LocalUser* user, const ClientProtocol::MessageTagData& tagdata) CXX11_OVERRIDE
+	{
+		// Messages only have a label when being sent to a user that sent one.
+		return user == labeluser && tagdata.value == label;
+	}
+};
+
+class ModuleIRCv3LabeledResponse : public Module
+{
+ private:
+	Cap::Capability cap;
+	LabeledResponseTag tag;
+	IRCv3::Batch::API batchmanager;
+	IRCv3::Batch::Batch batch;
+	IRCv3::Batch::CapReference batchcap;
+	ClientProtocol::EventProvider ackmsgprov;
+	ClientProtocol::EventProvider labelmsgprov;
+	insp::aligned_storage<ClientProtocol::Message> firstmsg;
+	size_t msgcount;
+
+	void FlushFirstMsg(LocalUser* user)
+	{
+		// This isn't a side effect but we treat it like one to avoid the logic in OnUserWrite.
+		firstmsg->SetSideEffect(true);
+		user->Send(labelmsgprov, *firstmsg);
+		firstmsg->~Message();
+	}
+
+ public:
+	ModuleIRCv3LabeledResponse()
+		: cap(this, "labeled-response")
+		, tag(this, cap)
+		, batchmanager(this)
+		, batch("labeled-response")
+		, batchcap(this)
+		, ackmsgprov(this, "ACK")
+		, labelmsgprov(this, "labeled")
+		, msgcount(0)
+
+	{
+	}
+
+	ModResult OnPreCommand(std::string& command, CommandBase::Params& parameters, LocalUser* user, bool validated) CXX11_OVERRIDE
+	{
+		// We only care about the initial unvalidated OnPreCommand call.
+		if (validated || tag.labeluser)
+			return MOD_RES_PASSTHRU;
+
+		// We only care about registered users with the labeled-response and batch caps.
+		if (user->registered != REG_ALL || !cap.get(user) || !batchcap.get(user))
+			return MOD_RES_PASSTHRU;
+
+		const ClientProtocol::TagMap& tagmap = parameters.GetTags();
+		const ClientProtocol::TagMap::const_iterator labeltag = tagmap.find(tag.labeltag);
+		if (labeltag == tagmap.end())
+			return MOD_RES_PASSTHRU;
+
+		tag.label = labeltag->second.value;
+		tag.labeluser = user;
+		return MOD_RES_PASSTHRU;
+	}
+
+	void OnPostCommand(Command* command, const CommandBase::Params& parameters, LocalUser* user, CmdResult result, bool loop) CXX11_OVERRIDE
+	{
+		// Do nothing if this isn't the last OnPostCommand() run for the command.
+		//
+		// If a parameter for the command was originally a list and the command handler chose to be executed
+		// for each element on the list with synthesized parameters (CommandHandler::LoopCall) then this hook
+		// too will run for each element on the list plus once after the whole list has been processed.
+		// loop will only be false for the last run.
+		if (!loop)
+			OnCommandBlocked(command->name, parameters, user);
+	}
+
+	void OnCommandBlocked(const std::string& command, const CommandBase::Params& parameters, LocalUser* user) CXX11_OVERRIDE
+	{
+		// If no label was sent we don't have to do anything.
+		if (!tag.labeluser)
+			return;
+
+		switch (msgcount)
+		{
+			case 0:
+			{
+				// There was no response so we send an ACK instead.
+				ClientProtocol::Message ackmsg("ACK", ServerInstance->FakeClient);
+				ackmsg.AddTag(tag.labeltag, &tag, tag.label);
+				ackmsg.SetSideEffect(true);
+				tag.labeluser->Send(ackmsgprov, ackmsg);
+				break;
+			}
+
+			case 1:
+			{
+				// There was one response which was cached; send it now.
+				firstmsg->AddTag(tag.labeltag, &tag, tag.label);
+				FlushFirstMsg(user);
+				break;
+			}
+
+			default:
+			{
+				// There was two or more responses; send an end-of-batch.
+				if (batchmanager)
+				{
+					// Set end start as side effect so we'll ignore it otherwise it'd end up added into the batch.
+					batch.GetBatchEndMessage().SetSideEffect(true);
+					batchmanager->End(batch);
+				}
+				break;
+			}
+		}
+
+		tag.labeluser = NULL;
+		msgcount = 0;
+	}
+
+	ModResult OnUserWrite(LocalUser* user, ClientProtocol::Message& msg) CXX11_OVERRIDE
+	{
+		// The label user is writing a message to another user.
+		if (user != tag.labeluser)
+			return MOD_RES_PASSTHRU;
+
+		// The message is a side effect (e.g. a self-PRIVMSG).
+		if (msg.IsSideEffect())
+			return MOD_RES_PASSTHRU;
+
+		switch (++msgcount)
+		{
+			case 1:
+			{
+				// First reply message. We can' send it yet because we don't know if there will be more.
+				new(firstmsg) ClientProtocol::Message(msg);
+				firstmsg->CopyAll();
+				return MOD_RES_DENY;
+			}
+
+			case 2:
+			{
+				// Second reply message. This and all subsequent messages need to go into a batch.
+				if (batchmanager)
+				{
+					batchmanager->Start(batch);
+
+					// Set batch start as side effect so we'll ignore it otherwise it'd end up added into the batch.
+					ClientProtocol::Message& batchstartmsg = batch.GetBatchStartMessage();
+					batchstartmsg.SetSideEffect(true);
+					batchstartmsg.AddTag(tag.labeltag, &tag, tag.label);
+
+					batch.AddToBatch(*firstmsg);
+					batch.AddToBatch(msg);
+				}
+
+				// Flush first message which triggers the batch start message
+				FlushFirstMsg(user);
+				return MOD_RES_PASSTHRU;
+			}
+
+			default:
+			{
+				// Third or later message. Put it in the batch and send directly.
+				if (batchmanager)
+					batch.AddToBatch(msg);
+				return MOD_RES_PASSTHRU;
+			}
+		}
+	}
+
+	void Prioritize() CXX11_OVERRIDE
+	{
+		Module* alias = ServerInstance->Modules->Find("m_alias.so");
+		ServerInstance->Modules->SetPriority(this, I_OnPreCommand, PRIORITY_BEFORE, alias);
+	}
+
+	Version GetVersion() CXX11_OVERRIDE
+	{
+		return Version("Provides the DRAFT labeled-response IRCv3 extension", VF_VENDOR);
+	}
+};
+
+MODULE_INIT(ModuleIRCv3LabeledResponse)