[MP] Add MultiplayerPeer disconnect_peer, close.

Update ENet, WebRTC, and WebSocket to support peer disconnection and
unify the close function.

3 files changed, 112 insertions, 157 deletions

diff --git a/modules/enet/doc_classes/ENetMultiplayerPeer.xml b/modules/enet/doc_classes/ENetMultiplayerPeer.xml
index f02fc893fd..2e0d1f5079 100644
--- a/modules/enet/doc_classes/ENetMultiplayerPeer.xml
+++ b/modules/enet/doc_classes/ENetMultiplayerPeer.xml
@@ -21,13 +21,6 @@
 				[b]Note:[/b] The [code]host[/code] must have exactly one peer in the [constant ENetPacketPeer.STATE_CONNECTED] state.
 			</description>
 		</method>
-		<method name="close_connection">
-			<return type="void" />
-			<param index="0" name="wait_usec" type="int" default="100" />
-			<description>
-				Closes the connection. Ignored if no connection is currently established. If this is a server it tries to notify all clients before forcibly disconnecting them. If this is a client it simply closes the connection to the server.
-			</description>
-		</method>
 		<method name="create_client">
 			<return type="int" enum="Error" />
 			<param index="0" name="address" type="String" />
@@ -37,7 +30,7 @@
 			<param index="4" name="out_bandwidth" type="int" default="0" />
 			<param index="5" name="local_port" type="int" default="0" />
 			<description>
-				Create client that connects to a server at [code]address[/code] using specified [code]port[/code]. The given address needs to be either a fully qualified domain name (e.g. [code]"www.example.com"[/code]) or an IP address in IPv4 or IPv6 format (e.g. [code]"192.168.1.1"[/code]). The [code]port[/code] is the port the server is listening on. The [code]channel_count[/code] parameter can be used to specify the number of ENet channels allocated for the connection. The [code]in_bandwidth[/code] and [code]out_bandwidth[/code] parameters can be used to limit the incoming and outgoing bandwidth to the given number of bytes per second. The default of 0 means unlimited bandwidth. Note that ENet will strategically drop packets on specific sides of a connection between peers to ensure the peer's bandwidth is not overwhelmed. The bandwidth parameters also determine the window size of a connection which limits the amount of reliable packets that may be in transit at any given time. Returns [constant OK] if a client was created, [constant ERR_ALREADY_IN_USE] if this ENetMultiplayerPeer instance already has an open connection (in which case you need to call [method close_connection] first) or [constant ERR_CANT_CREATE] if the client could not be created. If [code]local_port[/code] is specified, the client will also listen to the given port; this is useful for some NAT traversal techniques.
+				Create client that connects to a server at [code]address[/code] using specified [code]port[/code]. The given address needs to be either a fully qualified domain name (e.g. [code]"www.example.com"[/code]) or an IP address in IPv4 or IPv6 format (e.g. [code]"192.168.1.1"[/code]). The [code]port[/code] is the port the server is listening on. The [code]channel_count[/code] parameter can be used to specify the number of ENet channels allocated for the connection. The [code]in_bandwidth[/code] and [code]out_bandwidth[/code] parameters can be used to limit the incoming and outgoing bandwidth to the given number of bytes per second. The default of 0 means unlimited bandwidth. Note that ENet will strategically drop packets on specific sides of a connection between peers to ensure the peer's bandwidth is not overwhelmed. The bandwidth parameters also determine the window size of a connection which limits the amount of reliable packets that may be in transit at any given time. Returns [constant OK] if a client was created, [constant ERR_ALREADY_IN_USE] if this ENetMultiplayerPeer instance already has an open connection (in which case you need to call [method MultiplayerPeer.close] first) or [constant ERR_CANT_CREATE] if the client could not be created. If [code]local_port[/code] is specified, the client will also listen to the given port; this is useful for some NAT traversal techniques.
 			</description>
 		</method>
 		<method name="create_mesh">
@@ -55,7 +48,7 @@
 			<param index="3" name="in_bandwidth" type="int" default="0" />
 			<param index="4" name="out_bandwidth" type="int" default="0" />
 			<description>
-				Create server that listens to connections via [code]port[/code]. The port needs to be an available, unused port between 0 and 65535. Note that ports below 1024 are privileged and may require elevated permissions depending on the platform. To change the interface the server listens on, use [method set_bind_ip]. The default IP is the wildcard [code]"*"[/code], which listens on all available interfaces. [code]max_clients[/code] is the maximum number of clients that are allowed at once, any number up to 4095 may be used, although the achievable number of simultaneous clients may be far lower and depends on the application. For additional details on the bandwidth parameters, see [method create_client]. Returns [constant OK] if a server was created, [constant ERR_ALREADY_IN_USE] if this ENetMultiplayerPeer instance already has an open connection (in which case you need to call [method close_connection] first) or [constant ERR_CANT_CREATE] if the server could not be created.
+				Create server that listens to connections via [code]port[/code]. The port needs to be an available, unused port between 0 and 65535. Note that ports below 1024 are privileged and may require elevated permissions depending on the platform. To change the interface the server listens on, use [method set_bind_ip]. The default IP is the wildcard [code]"*"[/code], which listens on all available interfaces. [code]max_clients[/code] is the maximum number of clients that are allowed at once, any number up to 4095 may be used, although the achievable number of simultaneous clients may be far lower and depends on the application. For additional details on the bandwidth parameters, see [method create_client]. Returns [constant OK] if a server was created, [constant ERR_ALREADY_IN_USE] if this ENetMultiplayerPeer instance already has an open connection (in which case you need to call [method MultiplayerPeer.close] first) or [constant ERR_CANT_CREATE] if the server could not be created.
 			</description>
 		</method>
 		<method name="get_peer" qualifiers="const">
diff --git a/modules/enet/enet_multiplayer_peer.cpp b/modules/enet/enet_multiplayer_peer.cpp
index c93db3b972..31ae643b59 100644
--- a/modules/enet/enet_multiplayer_peer.cpp
+++ b/modules/enet/enet_multiplayer_peer.cpp
@@ -146,92 +146,24 @@ void ENetMultiplayerPeer::_store_packet(int32_t p_source, ENetConnection::Event
 	incoming_packets.push_back(packet);
 }
 
-bool ENetMultiplayerPeer::_parse_server_event(ENetConnection::EventType p_type, ENetConnection::Event &p_event) {
-	switch (p_type) {
-		case ENetConnection::EVENT_CONNECT: {
-			if (is_refusing_new_connections()) {
-				p_event.peer->reset();
-				return false;
-			}
-			// Client joined with invalid ID, probably trying to exploit us.
-			if (p_event.data < 2 || peers.has((int)p_event.data)) {
-				p_event.peer->reset();
-				return false;
-			}
-			int id = p_event.data;
-			p_event.peer->set_meta(SNAME("_net_id"), id);
-			peers[id] = p_event.peer;
-
-			emit_signal(SNAME("peer_connected"), id);
-			return false;
-		}
-		case ENetConnection::EVENT_DISCONNECT: {
-			int id = p_event.peer->get_meta(SNAME("_net_id"));
-			if (!peers.has(id)) {
-				// Never fully connected.
-				return false;
-			}
-
-			emit_signal(SNAME("peer_disconnected"), id);
-			peers.erase(id);
-			return false;
-		}
-		case ENetConnection::EVENT_RECEIVE: {
-			int32_t source = p_event.peer->get_meta(SNAME("_net_id"));
-			_store_packet(source, p_event);
-			return false;
+void ENetMultiplayerPeer::_disconnect_inactive_peers() {
+	HashSet<int> to_drop;
+	for (const KeyValue<int, Ref<ENetPacketPeer>> &E : peers) {
+		if (E.value->is_active()) {
+			continue;
 		}
-		default:
-			return true;
+		to_drop.insert(E.key);
 	}
-}
-
-bool ENetMultiplayerPeer::_parse_client_event(ENetConnection::EventType p_type, ENetConnection::Event &p_event) {
-	switch (p_type) {
-		case ENetConnection::EVENT_CONNECT: {
-			connection_status = CONNECTION_CONNECTED;
-			emit_signal(SNAME("peer_connected"), 1);
-			emit_signal(SNAME("connection_succeeded"));
-			return false;
+	for (const int &P : to_drop) {
+		peers.erase(P);
+		if (hosts.has(P)) {
+			hosts.erase(P);
 		}
-		case ENetConnection::EVENT_DISCONNECT: {
-			if (connection_status == CONNECTION_CONNECTED) {
-				// Client just disconnected from server.
-				emit_signal(SNAME("server_disconnected"));
-			} else {
-				emit_signal(SNAME("connection_failed"));
-			}
-			close_connection();
-			return true;
+		if (active_mode == MODE_CLIENT) {
+			ERR_CONTINUE(P != TARGET_PEER_SERVER);
+			emit_signal(SNAME("server_disconnected"));
 		}
-		case ENetConnection::EVENT_RECEIVE: {
-			_store_packet(1, p_event);
-			return false;
-		}
-		default:
-			return true;
-	}
-}
-
-bool ENetMultiplayerPeer::_parse_mesh_event(ENetConnection::EventType p_type, ENetConnection::Event &p_event, int p_peer_id) {
-	switch (p_type) {
-		case ENetConnection::EVENT_CONNECT:
-			p_event.peer->reset();
-			return false;
-		case ENetConnection::EVENT_DISCONNECT:
-			if (peers.has(p_peer_id)) {
-				emit_signal(SNAME("peer_disconnected"), p_peer_id);
-				peers.erase(p_peer_id);
-			}
-			hosts.erase(p_peer_id);
-			return true;
-		case ENetConnection::EVENT_RECEIVE: {
-			_store_packet(p_peer_id, p_event);
-			return false;
-		} break;
-		default:
-			// Nothing to do
-			return true;
+		emit_signal(SNAME("peer_disconnected"), P);
 	}
 }
 
@@ -240,74 +172,96 @@ void ENetMultiplayerPeer::poll() {
 
 	_pop_current_packet();
 
+	_disconnect_inactive_peers();
+
 	switch (active_mode) {
 		case MODE_CLIENT: {
-			if (peers.has(1) && !peers[1]->is_active()) {
-				if (connection_status == CONNECTION_CONNECTED) {
-					// Client just disconnected from server.
-					emit_signal(SNAME("server_disconnected"));
-				} else {
-					emit_signal(SNAME("connection_failed"));
-				}
-				close_connection();
+			if (!peers.has(1)) {
+				close();
 				return;
 			}
 			ENetConnection::Event event;
 			ENetConnection::EventType ret = hosts[0]->service(0, event);
-			if (ret == ENetConnection::EVENT_ERROR) {
-				return;
-			}
 			do {
-				if (_parse_client_event(ret, event)) {
-					return;
+				if (ret == ENetConnection::EVENT_CONNECT) {
+					connection_status = CONNECTION_CONNECTED;
+					emit_signal(SNAME("peer_connected"), 1);
+					emit_signal(SNAME("connection_succeeded"));
+				} else if (ret == ENetConnection::EVENT_DISCONNECT) {
+					if (connection_status == CONNECTION_CONNECTED) {
+						// Client just disconnected from server.
+						emit_signal(SNAME("server_disconnected"));
+						emit_signal(SNAME("peer_disconnected"), 1);
+					} else {
+						emit_signal(SNAME("connection_failed"));
+					}
+					close();
+				} else if (ret == ENetConnection::EVENT_RECEIVE) {
+					_store_packet(1, event);
+				} else if (ret != ENetConnection::EVENT_NONE) {
+					close(); // Error.
 				}
-			} while (hosts[0]->check_events(ret, event) > 0);
+			} while (hosts.has(0) && hosts[0]->check_events(ret, event) > 0);
 		} break;
 		case MODE_SERVER: {
-			for (const KeyValue<int, Ref<ENetPacketPeer>> &E : peers) {
-				if (!(E.value->is_active())) {
-					emit_signal(SNAME("peer_disconnected"), E.value->get_meta(SNAME("_net_id")));
-					peers.erase(E.key);
-				}
-			}
 			ENetConnection::Event event;
 			ENetConnection::EventType ret = hosts[0]->service(0, event);
-			if (ret == ENetConnection::EVENT_ERROR) {
-				return;
-			}
 			do {
-				if (_parse_server_event(ret, event)) {
-					return;
+				if (ret == ENetConnection::EVENT_CONNECT) {
+					if (is_refusing_new_connections()) {
+						event.peer->reset();
+						continue;
+					}
+					// Client joined with invalid ID, probably trying to exploit us.
+					if (event.data < 2 || peers.has((int)event.data)) {
+						event.peer->reset();
+						continue;
+					}
+					int id = event.data;
+					event.peer->set_meta(SNAME("_net_id"), id);
+					peers[id] = event.peer;
+					emit_signal(SNAME("peer_connected"), id);
+				} else if (ret == ENetConnection::EVENT_DISCONNECT) {
+					int id = event.peer->get_meta(SNAME("_net_id"));
+					if (!peers.has(id)) {
+						// Never fully connected.
+						continue;
+					}
+					emit_signal(SNAME("peer_disconnected"), id);
+					peers.erase(id);
+				} else if (ret == ENetConnection::EVENT_RECEIVE) {
+					int32_t source = event.peer->get_meta(SNAME("_net_id"));
+					_store_packet(source, event);
+				} else if (ret != ENetConnection::EVENT_NONE) {
+					close(); // Error
 				}
-			} while (hosts[0]->check_events(ret, event) > 0);
+			} while (hosts.has(0) && hosts[0]->check_events(ret, event) > 0);
 		} break;
 		case MODE_MESH: {
-			for (const KeyValue<int, Ref<ENetPacketPeer>> &E : peers) {
-				if (!(E.value->is_active())) {
-					emit_signal(SNAME("peer_disconnected"), E.key);
-					peers.erase(E.key);
-					if (hosts.has(E.key)) {
-						hosts.erase(E.key);
-					}
-				}
-			}
+			HashSet<int> to_drop;
 			for (KeyValue<int, Ref<ENetConnection>> &E : hosts) {
 				ENetConnection::Event event;
 				ENetConnection::EventType ret = E.value->service(0, event);
-				if (ret == ENetConnection::EVENT_ERROR) {
-					if (peers.has(E.key)) {
-						emit_signal(SNAME("peer_disconnected"), E.key);
-						peers.erase(E.key);
-					}
-					hosts.erase(E.key);
-					continue;
-				}
 				do {
-					if (_parse_mesh_event(ret, event, E.key)) {
+					if (ret == ENetConnection::EVENT_CONNECT) {
+						event.peer->reset();
+					} else if (ret == ENetConnection::EVENT_RECEIVE) {
+						_store_packet(E.key, event);
+					} else if (ret == ENetConnection::EVENT_NONE) {
+						break; // Keep polling the others.
+					} else {
+						to_drop.insert(E.key); // Error or disconnect.
 						break; // Keep polling the others.
 					}
 				} while (E.value->check_events(ret, event) > 0);
 			}
+			for (const int &P : to_drop) {
+				if (peers.has(P)) {
+					emit_signal(SNAME("peer_disconnected"), P);
+					peers.erase(P);
+				}
+				hosts.erase(P);
+			}
 		} break;
 		default:
 			return;
@@ -322,29 +276,41 @@ bool ENetMultiplayerPeer::is_server_relay_supported() const {
 	return active_mode == MODE_SERVER || active_mode == MODE_CLIENT;
 }
 
-void ENetMultiplayerPeer::close_connection(uint32_t wait_usec) {
+void ENetMultiplayerPeer::disconnect_peer(int p_peer, bool p_force) {
+	ERR_FAIL_COND(!_is_active() || !peers.has(p_peer));
+	peers[p_peer]->peer_disconnect(0); // Will be removed during next poll.
+	if (active_mode == MODE_CLIENT || active_mode == MODE_SERVER) {
+		hosts[0]->flush();
+	} else {
+		ERR_FAIL_COND(!hosts.has(p_peer));
+		hosts[p_peer]->flush();
+	}
+	if (p_force) {
+		peers.erase(p_peer);
+		if (hosts.has(p_peer)) {
+			hosts.erase(p_peer);
+		}
+		if (active_mode == MODE_CLIENT) {
+			hosts.clear(); // Avoid flushing again.
+			close();
+		}
+	}
+}
+
+void ENetMultiplayerPeer::close() {
 	if (!_is_active()) {
 		return;
 	}
 
 	_pop_current_packet();
 
-	bool peers_disconnected = false;
 	for (KeyValue<int, Ref<ENetPacketPeer>> &E : peers) {
 		if (E.value.is_valid() && E.value->get_state() == ENetPacketPeer::STATE_CONNECTED) {
-			E.value->peer_disconnect_now(unique_id);
-			peers_disconnected = true;
+			E.value->peer_disconnect_now(0);
 		}
 	}
-
-	if (peers_disconnected) {
-		for (KeyValue<int, Ref<ENetConnection>> &E : hosts) {
-			E.value->flush();
-		}
-
-		if (wait_usec > 0) {
-			OS::get_singleton()->delay_usec(wait_usec); // Wait for disconnection packets to send
-		}
+	for (KeyValue<int, Ref<ENetConnection>> &E : hosts) {
+		E.value->flush();
 	}
 
 	active_mode = MODE_NONE;
@@ -516,7 +482,6 @@ void ENetMultiplayerPeer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("create_client", "address", "port", "channel_count", "in_bandwidth", "out_bandwidth", "local_port"), &ENetMultiplayerPeer::create_client, DEFVAL(0), DEFVAL(0), DEFVAL(0), DEFVAL(0));
 	ClassDB::bind_method(D_METHOD("create_mesh", "unique_id"), &ENetMultiplayerPeer::create_mesh);
 	ClassDB::bind_method(D_METHOD("add_mesh_peer", "peer_id", "host"), &ENetMultiplayerPeer::add_mesh_peer);
-	ClassDB::bind_method(D_METHOD("close_connection", "wait_usec"), &ENetMultiplayerPeer::close_connection, DEFVAL(100));
 	ClassDB::bind_method(D_METHOD("set_bind_ip", "ip"), &ENetMultiplayerPeer::set_bind_ip);
 
 	ClassDB::bind_method(D_METHOD("get_host"), &ENetMultiplayerPeer::get_host);
@@ -531,7 +496,7 @@ ENetMultiplayerPeer::ENetMultiplayerPeer() {
 
 ENetMultiplayerPeer::~ENetMultiplayerPeer() {
 	if (_is_active()) {
-		close_connection();
+		close();
 	}
 }
 
diff --git a/modules/enet/enet_multiplayer_peer.h b/modules/enet/enet_multiplayer_peer.h
index 85692e8eee..2665b69669 100644
--- a/modules/enet/enet_multiplayer_peer.h
+++ b/modules/enet/enet_multiplayer_peer.h
@@ -83,9 +83,7 @@ private:
 
 	void _store_packet(int32_t p_source, ENetConnection::Event &p_event);
 	void _pop_current_packet();
-	bool _parse_server_event(ENetConnection::EventType p_event_type, ENetConnection::Event &p_event);
-	bool _parse_client_event(ENetConnection::EventType p_event_type, ENetConnection::Event &p_event);
-	bool _parse_mesh_event(ENetConnection::EventType p_event_type, ENetConnection::Event &p_event, int p_peer_id);
+	void _disconnect_inactive_peers();
 	void _destroy_unused(ENetPacket *p_packet);
 	_FORCE_INLINE_ bool _is_active() const { return active_mode != MODE_NONE; }
 
@@ -102,6 +100,9 @@ public:
 	virtual int get_packet_channel() const override;
 
 	virtual void poll() override;
+	virtual void close() override;
+	virtual void disconnect_peer(int p_peer, bool p_force = false) override;
+
 	virtual bool is_server() const override;
 	virtual bool is_server_relay_supported() const override;
 
@@ -122,10 +123,6 @@ public:
 	Error create_mesh(int p_id);
 	Error add_mesh_peer(int p_id, Ref<ENetConnection> p_host);
 
-	void close_connection(uint32_t wait_usec = 100);
-
-	void disconnect_peer(int p_peer, bool now = false);
-
 	void set_bind_ip(const IPAddress &p_ip);
 
 	Ref<ENetConnection> get_host() const;