Implement mod communication channels (#6351)

Implement network communication for channels

* Implement ModChannel manager server side to route incoming messages from clients to other clients
* Add signal handler switch on client & ModChannelMgr on client to handle channels
* Add Lua API bindings + client packet sending + unittests
* Implement server message sending
* Add callback from received message handler to Lua API using registration method

1 files changed, 92 insertions, 0 deletions

diff --git a/src/modchannels.h b/src/modchannels.h
new file mode 100644
index 000000000..5f1aa884e
--- /dev/null
+++ b/src/modchannels.h
@@ -0,0 +1,92 @@
+/*
+Minetest
+Copyright (C) 2017 nerzhul, Loic Blot <loic.blot@unix-experience.fr>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+
+#include <unordered_map>
+#include <string>
+#include <vector>
+#include <memory>
+#include "irrlichttypes.h"
+
+enum ModChannelState : u8
+{
+	MODCHANNEL_STATE_INIT,
+	MODCHANNEL_STATE_READ_WRITE,
+	MODCHANNEL_STATE_READ_ONLY,
+	MODCHANNEL_STATE_MAX,
+};
+
+class ModChannel
+{
+public:
+	ModChannel(const std::string &name) : m_name(name) {}
+	~ModChannel() = default;
+
+	const std::string &getName() const { return m_name; }
+	bool registerConsumer(u16 peer_id);
+	bool removeConsumer(u16 peer_id);
+	const std::vector<u16> &getChannelPeers() const { return m_client_consumers; }
+	bool canWrite() const;
+	void setState(ModChannelState state);
+
+private:
+	std::string m_name;
+	ModChannelState m_state = MODCHANNEL_STATE_INIT;
+	std::vector<u16> m_client_consumers;
+};
+
+enum ModChannelSignal : u8
+{
+	MODCHANNEL_SIGNAL_JOIN_OK,
+	MODCHANNEL_SIGNAL_JOIN_FAILURE,
+	MODCHANNEL_SIGNAL_LEAVE_OK,
+	MODCHANNEL_SIGNAL_LEAVE_FAILURE,
+	MODCHANNEL_SIGNAL_CHANNEL_NOT_REGISTERED,
+	MODCHANNEL_SIGNAL_SET_STATE,
+};
+
+class ModChannelMgr
+{
+public:
+	ModChannelMgr() = default;
+	~ModChannelMgr() = default;
+
+	void registerChannel(const std::string &channel);
+	bool setChannelState(const std::string &channel, ModChannelState state);
+	bool joinChannel(const std::string &channel, u16 peer_id);
+	bool leaveChannel(const std::string &channel, u16 peer_id);
+	bool channelRegistered(const std::string &channel) const;
+	ModChannel *getModChannel(const std::string &channel);
+	/**
+	 * This function check if a local mod can write on the channel
+	 *
+	 * @param channel
+	 * @return true if write is allowed
+	 */
+	bool canWriteOnChannel(const std::string &channel) const;
+	void leaveAllChannels(u16 peer_id);
+	const std::vector<u16> &getChannelPeers(const std::string &channel) const;
+
+private:
+	bool removeChannel(const std::string &channel);
+
+	std::unordered_map<std::string, std::unique_ptr<ModChannel>>
+			m_registered_channels;
+};