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

5 files changed, 238 insertions, 29 deletions

diff --git a/src/network/clientopcodes.cpp b/src/network/clientopcodes.cpp
index fa63fba65..bc5bd37dd 100644
--- a/src/network/clientopcodes.cpp
+++ b/src/network/clientopcodes.cpp
@@ -111,8 +111,8 @@ const ToClientCommandHandler toClientCommandTable[TOCLIENT_NUM_MSG_TYPES] =
 	{ "TOCLIENT_CLOUD_PARAMS",             TOCLIENT_STATE_CONNECTED, &Client::handleCommand_CloudParams }, // 0x54
 	{ "TOCLIENT_FADE_SOUND",               TOCLIENT_STATE_CONNECTED, &Client::handleCommand_FadeSound }, // 0x55
 	{ "TOCLIENT_UPDATE_PLAYER_LIST",       TOCLIENT_STATE_CONNECTED, &Client::handleCommand_UpdatePlayerList }, // 0x56
-	null_command_handler,
-	null_command_handler,
+	{ "TOCLIENT_MODCHANNEL_MSG",           TOCLIENT_STATE_CONNECTED, &Client::handleCommand_ModChannelMsg }, // 0x57
+	{ "TOCLIENT_MODCHANNEL_SIGNAL",        TOCLIENT_STATE_CONNECTED, &Client::handleCommand_ModChannelSignal }, // 0x58
 	null_command_handler,
 	null_command_handler,
 	null_command_handler,
@@ -150,9 +150,9 @@ const ServerCommandFactory serverCommandFactoryTable[TOSERVER_NUM_MSG_TYPES] =
 	null_command_factory, // 0x14
 	null_command_factory, // 0x15
 	null_command_factory, // 0x16
-	null_command_factory, // 0x17
-	null_command_factory, // 0x18
-	null_command_factory, // 0x19
+	{ "TOSERVER_MODCHANNEL_JOIN", 0, true }, // 0x17
+	{ "TOSERVER_MODCHANNEL_LEAVE", 0, true }, // 0x18
+	{ "TOSERVER_MODCHANNEL_MSG", 0, true }, // 0x19
 	null_command_factory, // 0x1a
 	null_command_factory, // 0x1b
 	null_command_factory, // 0x1c
diff --git a/src/network/clientpackethandler.cpp b/src/network/clientpackethandler.cpp
index 3ff23453d..b5e2203c8 100644
--- a/src/network/clientpackethandler.cpp
+++ b/src/network/clientpackethandler.cpp
@@ -26,6 +26,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "map.h"
 #include "mapsector.h"
 #include "minimap.h"
+#include "modchannels.h"
 #include "nodedef.h"
 #include "serialization.h"
 #include "server.h"
@@ -1330,3 +1331,95 @@ void Client::handleCommand_CSMFlavourLimits(NetworkPacket *pkt)
 {
 	*pkt >> m_csm_flavour_limits >> m_csm_noderange_limit;
 }
+
+/*
+ * Mod channels
+ */
+
+void Client::handleCommand_ModChannelMsg(NetworkPacket *pkt)
+{
+	std::string channel_name, sender, channel_msg;
+	*pkt >> channel_name >> sender >> channel_msg;
+
+	verbosestream << "Mod channel message received from server " << pkt->getPeerId()
+		<< " on channel " << channel_name << ". sender: `" << sender << "`, message: "
+		<< channel_msg << std::endl;
+
+	if (!m_modchannel_mgr->channelRegistered(channel_name)) {
+		verbosestream << "Server sent us messages on unregistered channel "
+			<< channel_name << ", ignoring." << std::endl;
+		return;
+	}
+
+	m_script->on_modchannel_message(channel_name, sender, channel_msg);
+}
+
+void Client::handleCommand_ModChannelSignal(NetworkPacket *pkt)
+{
+	u8 signal_tmp;
+	ModChannelSignal signal;
+	std::string channel;
+
+	*pkt >> signal_tmp >> channel;
+
+	signal = (ModChannelSignal)signal_tmp;
+
+	bool valid_signal = true;
+	// @TODO: send Signal to Lua API
+	switch (signal) {
+		case MODCHANNEL_SIGNAL_JOIN_OK:
+			m_modchannel_mgr->setChannelState(channel, MODCHANNEL_STATE_READ_WRITE);
+			infostream << "Server ack our mod channel join on channel `" << channel
+				<< "`, joining." << std::endl;
+			break;
+		case MODCHANNEL_SIGNAL_JOIN_FAILURE:
+			// Unable to join, remove channel
+			m_modchannel_mgr->leaveChannel(channel, 0);
+			infostream << "Server refused our mod channel join on channel `" << channel
+				<< "`" << std::endl;
+			break;
+		case MODCHANNEL_SIGNAL_LEAVE_OK:
+#ifndef NDEBUG
+			infostream << "Server ack our mod channel leave on channel " << channel
+				<< "`, leaving." << std::endl;
+#endif
+			break;
+		case MODCHANNEL_SIGNAL_LEAVE_FAILURE:
+			infostream << "Server refused our mod channel leave on channel `" << channel
+				<< "`" << std::endl;
+			break;
+		case MODCHANNEL_SIGNAL_CHANNEL_NOT_REGISTERED:
+#ifndef NDEBUG
+			// Generally unused, but ensure we don't do an implementation error
+			infostream << "Server tells us we sent a message on channel `" << channel
+				<< "` but we are not registered. Message was dropped." << std::endl;
+#endif
+			break;
+		case MODCHANNEL_SIGNAL_SET_STATE: {
+			u8 state;
+			*pkt >> state;
+
+			if (state == MODCHANNEL_STATE_INIT || state >= MODCHANNEL_STATE_MAX) {
+				infostream << "Received wrong channel state " << state
+						<< ", ignoring." << std::endl;
+				return;
+			}
+
+			m_modchannel_mgr->setChannelState(channel, (ModChannelState) state);
+			infostream << "Server sets mod channel `" << channel
+					<< "` in read-only mode." << std::endl;
+			break;
+		}
+		default:
+#ifndef NDEBUG
+			warningstream << "Received unhandled mod channel signal ID "
+				<< signal << ", ignoring." << std::endl;
+#endif
+			valid_signal = false;
+			break;
+	}
+
+	// If signal is valid, forward it to client side mods
+	if (valid_signal)
+		m_script->on_modchannel_signal(channel, signal);
+}
diff --git a/src/network/networkprotocol.h b/src/network/networkprotocol.h
index f4258e9cd..28132396b 100644
--- a/src/network/networkprotocol.h
+++ b/src/network/networkprotocol.h
@@ -180,6 +180,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 		Backwards compatibility drop
 		Add 'can_zoom' to player object properties
 		Add glow to object properties
+		Mod channels
 */
 
 #define LATEST_PROTOCOL_VERSION 36
@@ -611,6 +612,22 @@ enum ToClientCommand
 			u8[len] player name
 	*/
 
+	TOCLIENT_MODCHANNEL_MSG = 0x57,
+	/*
+		u16 channel name length
+	 	std::string channel name
+	 	u16 channel name sender
+	 	std::string channel name
+	 	u16 message length
+	 	std::string message
+	 */
+	TOCLIENT_MODCHANNEL_SIGNAL = 0x58,
+	/*
+		u8 signal id
+	 	u16 channel name length
+	 	std::string channel name
+	 */
+
 	TOCLIENT_SRP_BYTES_S_B = 0x60,
 	/*
 		Belonging to AUTH_MECHANISM_SRP.
@@ -645,6 +662,26 @@ enum ToServerCommand
 		[0] u16 TOSERVER_INIT2
 	*/
 
+	TOSERVER_MODCHANNEL_JOIN = 0x17,
+	/*
+		u16 channel name length
+	 	std::string channel name
+	 */
+
+	TOSERVER_MODCHANNEL_LEAVE = 0x18,
+	/*
+		u16 channel name length
+	 	std::string channel name
+	 */
+
+	TOSERVER_MODCHANNEL_MSG = 0x19,
+	/*
+		u16 channel name length
+	 	std::string channel name
+	 	u16 message length
+	 	std::string message
+	 */
+
 	TOSERVER_GETBLOCK = 0x20, // Obsolete
 	TOSERVER_ADDNODE = 0x21, // Obsolete
 	TOSERVER_REMOVENODE = 0x22, // Obsolete
diff --git a/src/network/serveropcodes.cpp b/src/network/serveropcodes.cpp
index 8c6d159cd..6dcf9c93a 100644
--- a/src/network/serveropcodes.cpp
+++ b/src/network/serveropcodes.cpp
@@ -47,9 +47,9 @@ const ToServerCommandHandler toServerCommandTable[TOSERVER_NUM_MSG_TYPES] =
 	null_command_handler, // 0x14
 	null_command_handler, // 0x15
 	null_command_handler, // 0x16
-	null_command_handler, // 0x17
-	null_command_handler, // 0x18
-	null_command_handler, // 0x19
+	{ "TOSERVER_MODCHANNEL_JOIN",          TOSERVER_STATE_INGAME, &Server::handleCommand_ModChannelJoin }, // 0x17
+	{ "TOSERVER_MODCHANNEL_LEAVE",         TOSERVER_STATE_INGAME, &Server::handleCommand_ModChannelLeave }, // 0x18
+	{ "TOSERVER_MODCHANNEL_MSG",           TOSERVER_STATE_INGAME, &Server::handleCommand_ModChannelMsg }, // 0x19
 	null_command_handler, // 0x1a
 	null_command_handler, // 0x1b
 	null_command_handler, // 0x1c
@@ -200,8 +200,8 @@ const ClientCommandFactory clientCommandFactoryTable[TOCLIENT_NUM_MSG_TYPES] =
 	{ "TOCLIENT_CLOUD_PARAMS",             0, true }, // 0x54
 	{ "TOCLIENT_FADE_SOUND",               0, true }, // 0x55
 	{ "TOCLIENT_UPDATE_PLAYER_LIST",       0, true }, // 0x56
-	null_command_factory,
-	null_command_factory,
+	{ "TOCLIENT_MODCHANNEL_MSG",           0, true}, // 0x57
+	{ "TOCLIENT_MODCHANNEL_SIGNAL",        0, true}, // 0x58
 	null_command_factory,
 	null_command_factory,
 	null_command_factory,
diff --git a/src/network/serverpackethandler.cpp b/src/network/serverpackethandler.cpp
index c4c0c9d0d..7d2f6009f 100644
--- a/src/network/serverpackethandler.cpp
+++ b/src/network/serverpackethandler.cpp
@@ -23,6 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "content_sao.h"
 #include "emerge.h"
 #include "mapblock.h"
+#include "modchannels.h"
 #include "nodedef.h"
 #include "remoteplayer.h"
 #include "rollback_interface.h"
@@ -363,7 +364,7 @@ void Server::handleCommand_ClientReady(NetworkPacket* pkt)
 		actionstream
 			<< "TOSERVER_CLIENT_READY stage 2 client init failed for peer_id: "
 			<< peer_id << std::endl;
-		m_con->DisconnectPeer(peer_id);
+		DisconnectPeer(peer_id);
 		return;
 	}
 
@@ -372,7 +373,7 @@ void Server::handleCommand_ClientReady(NetworkPacket* pkt)
 		errorstream
 			<< "TOSERVER_CLIENT_READY client sent inconsistent data, disconnecting peer_id: "
 			<< peer_id << std::endl;
-		m_con->DisconnectPeer(peer_id);
+		DisconnectPeer(peer_id);
 		return;
 	}
 
@@ -503,7 +504,7 @@ void Server::handleCommand_PlayerPos(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -512,7 +513,7 @@ void Server::handleCommand_PlayerPos(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player object for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -564,7 +565,7 @@ void Server::handleCommand_InventoryAction(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -573,7 +574,7 @@ void Server::handleCommand_InventoryAction(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player object for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -745,7 +746,7 @@ void Server::handleCommand_ChatMessage(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -773,7 +774,7 @@ void Server::handleCommand_Damage(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -782,7 +783,7 @@ void Server::handleCommand_Damage(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player object for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -839,7 +840,7 @@ void Server::handleCommand_Password(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -892,7 +893,7 @@ void Server::handleCommand_PlayerItem(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -901,7 +902,7 @@ void Server::handleCommand_PlayerItem(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player object for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -919,7 +920,7 @@ void Server::handleCommand_Respawn(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -972,7 +973,7 @@ void Server::handleCommand_Interact(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -981,7 +982,7 @@ void Server::handleCommand_Interact(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player object for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -1411,7 +1412,7 @@ void Server::handleCommand_NodeMetaFields(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -1420,7 +1421,7 @@ void Server::handleCommand_NodeMetaFields(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player object for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!"  << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -1462,7 +1463,7 @@ void Server::handleCommand_InventoryFields(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -1471,7 +1472,7 @@ void Server::handleCommand_InventoryFields(NetworkPacket* pkt)
 		errorstream << "Server::ProcessData(): Canceling: "
 				"No player object for peer_id=" << pkt->getPeerId()
 				<< " disconnecting peer!" << std::endl;
-		m_con->DisconnectPeer(pkt->getPeerId());
+		DisconnectPeer(pkt->getPeerId());
 		return;
 	}
 
@@ -1733,3 +1734,81 @@ void Server::handleCommand_SrpBytesM(NetworkPacket* pkt)
 
 	acceptAuth(pkt->getPeerId(), wantSudo);
 }
+
+/*
+ * Mod channels
+ */
+
+void Server::handleCommand_ModChannelJoin(NetworkPacket *pkt)
+{
+	std::string channel_name;
+	*pkt >> channel_name;
+
+	NetworkPacket resp_pkt(TOCLIENT_MODCHANNEL_SIGNAL, 1 + 2 + channel_name.size(),
+		pkt->getPeerId());
+
+	// Send signal to client to notify join succeed or not
+	if (g_settings->getBool("enable_mod_channels") &&
+			m_modchannel_mgr->joinChannel(channel_name, pkt->getPeerId())) {
+		resp_pkt << (u8) MODCHANNEL_SIGNAL_JOIN_OK;
+		infostream << "Peer " << pkt->getPeerId() << " joined channel " << channel_name
+				<< std::endl;
+	}
+	else {
+		resp_pkt << (u8)MODCHANNEL_SIGNAL_JOIN_FAILURE;
+		infostream << "Peer " << pkt->getPeerId() << " tried to join channel "
+			<< channel_name << ", but was already registered." << std::endl;
+	}
+	resp_pkt << channel_name;
+	Send(&resp_pkt);
+}
+
+void Server::handleCommand_ModChannelLeave(NetworkPacket *pkt)
+{
+	std::string channel_name;
+	*pkt >> channel_name;
+
+	NetworkPacket resp_pkt(TOCLIENT_MODCHANNEL_SIGNAL, 1 + 2 + channel_name.size(),
+		pkt->getPeerId());
+
+	// Send signal to client to notify join succeed or not
+	if (g_settings->getBool("enable_mod_channels") &&
+			m_modchannel_mgr->leaveChannel(channel_name, pkt->getPeerId())) {
+		resp_pkt << (u8)MODCHANNEL_SIGNAL_LEAVE_OK;
+		infostream << "Peer " << pkt->getPeerId() << " left channel " << channel_name
+				<< std::endl;
+	} else {
+		resp_pkt << (u8) MODCHANNEL_SIGNAL_LEAVE_FAILURE;
+		infostream << "Peer " << pkt->getPeerId() << " left channel " << channel_name
+				<< ", but was not registered." << std::endl;
+	}
+	resp_pkt << channel_name;
+	Send(&resp_pkt);
+}
+
+void Server::handleCommand_ModChannelMsg(NetworkPacket *pkt)
+{
+	std::string channel_name, channel_msg;
+	*pkt >> channel_name >> channel_msg;
+
+	verbosestream << "Mod channel message received from peer " << pkt->getPeerId()
+			<< " on channel " << channel_name << " message: " << channel_msg << std::endl;
+
+	// If mod channels are not enabled, discard message
+	if (!g_settings->getBool("enable_mod_channels")) {
+		return;
+	}
+
+	// If channel not registered, signal it and ignore message
+	if (!m_modchannel_mgr->channelRegistered(channel_name)) {
+		NetworkPacket resp_pkt(TOCLIENT_MODCHANNEL_SIGNAL, 1 + 2 + channel_name.size(),
+			pkt->getPeerId());
+		resp_pkt << (u8)MODCHANNEL_SIGNAL_CHANNEL_NOT_REGISTERED << channel_name;
+		Send(&resp_pkt);
+		return;
+	}
+
+	// @TODO: filter, rate limit
+
+	broadcastModChannelMessage(channel_name, channel_msg, pkt->getPeerId());
+}