[Net] Modularize multiplayer, expose MultiplayerAPI to extensions.

- RPC configurations are now dictionaries.
- Script.get_rpc_methods renamed to Script.get_rpc_config.
- Node.rpc[_id] and Callable.rpc now return an Error.
- Refactor MultiplayerAPI to allow extension.
- New MultiplayerAPI.rpc method with Array argument (for scripts).
- Move the default MultiplayerAPI implementation to a module.

1 files changed, 302 insertions, 0 deletions

diff --git a/modules/multiplayer/multiplayer_spawner.cpp b/modules/multiplayer/multiplayer_spawner.cpp
new file mode 100644
index 0000000000..ca2fd1c023
--- /dev/null
+++ b/modules/multiplayer/multiplayer_spawner.cpp
@@ -0,0 +1,302 @@
+/*************************************************************************/
+/*  multiplayer_spawner.cpp                                              */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "multiplayer_spawner.h"
+
+#include "core/io/marshalls.h"
+#include "scene/main/multiplayer_api.h"
+#include "scene/main/window.h"
+#include "scene/scene_string_names.h"
+
+#ifdef TOOLS_ENABLED
+/* This is editor only */
+bool MultiplayerSpawner::_set(const StringName &p_name, const Variant &p_value) {
+	if (p_name == "_spawnable_scene_count") {
+		spawnable_scenes.resize(p_value);
+		notify_property_list_changed();
+		return true;
+	} else {
+		String ns = p_name;
+		if (ns.begins_with("scenes/")) {
+			uint32_t index = ns.get_slicec('/', 1).to_int();
+			ERR_FAIL_UNSIGNED_INDEX_V(index, spawnable_scenes.size(), false);
+			spawnable_scenes[index].path = p_value;
+			return true;
+		}
+	}
+	return false;
+}
+
+bool MultiplayerSpawner::_get(const StringName &p_name, Variant &r_ret) const {
+	if (p_name == "_spawnable_scene_count") {
+		r_ret = spawnable_scenes.size();
+		return true;
+	} else {
+		String ns = p_name;
+		if (ns.begins_with("scenes/")) {
+			uint32_t index = ns.get_slicec('/', 1).to_int();
+			ERR_FAIL_UNSIGNED_INDEX_V(index, spawnable_scenes.size(), false);
+			r_ret = spawnable_scenes[index].path;
+			return true;
+		}
+	}
+	return false;
+}
+
+void MultiplayerSpawner::_get_property_list(List<PropertyInfo> *p_list) const {
+	p_list->push_back(PropertyInfo(Variant::INT, "_spawnable_scene_count", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_EDITOR | PROPERTY_USAGE_ARRAY, "Auto Spawn List,scenes/"));
+	List<String> exts;
+	ResourceLoader::get_recognized_extensions_for_type("PackedScene", &exts);
+	String ext_hint;
+	for (const String &E : exts) {
+		if (!ext_hint.is_empty()) {
+			ext_hint += ",";
+		}
+		ext_hint += "*." + E;
+	}
+	for (uint32_t i = 0; i < spawnable_scenes.size(); i++) {
+		p_list->push_back(PropertyInfo(Variant::STRING, "scenes/" + itos(i), PROPERTY_HINT_FILE, ext_hint, PROPERTY_USAGE_EDITOR));
+	}
+}
+#endif
+void MultiplayerSpawner::add_spawnable_scene(const String &p_path) {
+	SpawnableScene sc;
+	sc.path = p_path;
+	if (Engine::get_singleton()->is_editor_hint()) {
+		ERR_FAIL_COND(!FileAccess::exists(p_path));
+	} else {
+		sc.cache = ResourceLoader::load(p_path);
+		ERR_FAIL_COND_MSG(sc.cache.is_null(), "Invalid spawnable scene: " + p_path);
+	}
+	spawnable_scenes.push_back(sc);
+}
+int MultiplayerSpawner::get_spawnable_scene_count() const {
+	return spawnable_scenes.size();
+}
+String MultiplayerSpawner::get_spawnable_scene(int p_idx) const {
+	return spawnable_scenes[p_idx].path;
+}
+void MultiplayerSpawner::clear_spawnable_scenes() {
+	spawnable_scenes.clear();
+}
+
+Vector<String> MultiplayerSpawner::_get_spawnable_scenes() const {
+	Vector<String> ss;
+	ss.resize(spawnable_scenes.size());
+	for (int i = 0; i < ss.size(); i++) {
+		ss.write[i] = spawnable_scenes[i].path;
+	}
+	return ss;
+}
+
+void MultiplayerSpawner::_set_spawnable_scenes(const Vector<String> &p_scenes) {
+	clear_spawnable_scenes();
+	for (int i = 0; i < p_scenes.size(); i++) {
+		add_spawnable_scene(p_scenes[i]);
+	}
+}
+
+void MultiplayerSpawner::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("add_spawnable_scene", "path"), &MultiplayerSpawner::add_spawnable_scene);
+	ClassDB::bind_method(D_METHOD("get_spawnable_scene_count"), &MultiplayerSpawner::get_spawnable_scene_count);
+	ClassDB::bind_method(D_METHOD("get_spawnable_scene", "path"), &MultiplayerSpawner::get_spawnable_scene);
+	ClassDB::bind_method(D_METHOD("clear_spawnable_scenes"), &MultiplayerSpawner::clear_spawnable_scenes);
+
+	ClassDB::bind_method(D_METHOD("_get_spawnable_scenes"), &MultiplayerSpawner::_get_spawnable_scenes);
+	ClassDB::bind_method(D_METHOD("_set_spawnable_scenes", "scenes"), &MultiplayerSpawner::_set_spawnable_scenes);
+
+	ADD_PROPERTY(PropertyInfo(Variant::PACKED_STRING_ARRAY, "_spawnable_scenes", PROPERTY_HINT_NONE, "", (PROPERTY_USAGE_STORAGE | PROPERTY_USAGE_INTERNAL)), "_set_spawnable_scenes", "_get_spawnable_scenes");
+
+	ClassDB::bind_method(D_METHOD("spawn", "data"), &MultiplayerSpawner::spawn, DEFVAL(Variant()));
+
+	ClassDB::bind_method(D_METHOD("get_spawn_path"), &MultiplayerSpawner::get_spawn_path);
+	ClassDB::bind_method(D_METHOD("set_spawn_path", "path"), &MultiplayerSpawner::set_spawn_path);
+	ADD_PROPERTY(PropertyInfo(Variant::NODE_PATH, "spawn_path", PROPERTY_HINT_NONE, ""), "set_spawn_path", "get_spawn_path");
+
+	ClassDB::bind_method(D_METHOD("get_spawn_limit"), &MultiplayerSpawner::get_spawn_limit);
+	ClassDB::bind_method(D_METHOD("set_spawn_limit", "limit"), &MultiplayerSpawner::set_spawn_limit);
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "spawn_limit", PROPERTY_HINT_RANGE, "0,1024,1,or_greater"), "set_spawn_limit", "get_spawn_limit");
+
+	GDVIRTUAL_BIND(_spawn_custom, "data");
+
+	ADD_SIGNAL(MethodInfo("despawned", PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "node", PROPERTY_HINT_RESOURCE_TYPE, "Node")));
+	ADD_SIGNAL(MethodInfo("spawned", PropertyInfo(Variant::INT, "scene_id"), PropertyInfo(Variant::OBJECT, "node", PROPERTY_HINT_RESOURCE_TYPE, "Node")));
+}
+
+void MultiplayerSpawner::_update_spawn_node() {
+#ifdef TOOLS_ENABLED
+	if (Engine::get_singleton()->is_editor_hint()) {
+		return;
+	}
+#endif
+	if (spawn_node.is_valid()) {
+		Node *node = Object::cast_to<Node>(ObjectDB::get_instance(spawn_node));
+		if (node && node->is_connected("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added))) {
+			node->disconnect("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added));
+		}
+	}
+	Node *node = spawn_path.is_empty() && is_inside_tree() ? nullptr : get_node_or_null(spawn_path);
+	if (node) {
+		spawn_node = node->get_instance_id();
+		if (get_spawnable_scene_count() && !GDVIRTUAL_IS_OVERRIDDEN(_spawn_custom)) {
+			node->connect("child_entered_tree", callable_mp(this, &MultiplayerSpawner::_node_added));
+		}
+	} else {
+		spawn_node = ObjectID();
+	}
+}
+
+void MultiplayerSpawner::_notification(int p_what) {
+	switch (p_what) {
+		case NOTIFICATION_POST_ENTER_TREE: {
+			_update_spawn_node();
+		} break;
+
+		case NOTIFICATION_EXIT_TREE: {
+			_update_spawn_node();
+
+			for (const KeyValue<ObjectID, SpawnInfo> &E : tracked_nodes) {
+				Node *node = Object::cast_to<Node>(ObjectDB::get_instance(E.key));
+				ERR_CONTINUE(!node);
+				node->disconnect(SceneStringNames::get_singleton()->tree_exiting, callable_mp(this, &MultiplayerSpawner::_node_exit));
+				// This is unlikely, but might still crash the engine.
+				if (node->is_connected(SceneStringNames::get_singleton()->ready, callable_mp(this, &MultiplayerSpawner::_node_ready))) {
+					node->disconnect(SceneStringNames::get_singleton()->ready, callable_mp(this, &MultiplayerSpawner::_node_ready));
+				}
+				get_multiplayer()->object_configuration_remove(node, this);
+			}
+			tracked_nodes.clear();
+		} break;
+	}
+}
+
+void MultiplayerSpawner::_node_added(Node *p_node) {
+	if (!get_multiplayer()->has_multiplayer_peer() || !is_multiplayer_authority()) {
+		return;
+	}
+	if (tracked_nodes.has(p_node->get_instance_id())) {
+		return;
+	}
+	const Node *parent = get_spawn_node();
+	if (!parent || p_node->get_parent() != parent) {
+		return;
+	}
+	int id = find_spawnable_scene_index_from_path(p_node->get_scene_file_path());
+	if (id == INVALID_ID) {
+		return;
+	}
+	const String name = p_node->get_name();
+	ERR_FAIL_COND_MSG(name.validate_node_name() != name, vformat("Unable to auto-spawn node with reserved name: %s. Make sure to add your replicated scenes via 'add_child(node, true)' to produce valid names.", name));
+	_track(p_node, Variant(), id);
+}
+
+NodePath MultiplayerSpawner::get_spawn_path() const {
+	return spawn_path;
+}
+
+void MultiplayerSpawner::set_spawn_path(const NodePath &p_path) {
+	spawn_path = p_path;
+	_update_spawn_node();
+}
+
+void MultiplayerSpawner::_track(Node *p_node, const Variant &p_argument, int p_scene_id) {
+	ObjectID oid = p_node->get_instance_id();
+	if (!tracked_nodes.has(oid)) {
+		tracked_nodes[oid] = SpawnInfo(p_argument.duplicate(true), p_scene_id);
+		p_node->connect(SceneStringNames::get_singleton()->tree_exiting, callable_mp(this, &MultiplayerSpawner::_node_exit), varray(p_node->get_instance_id()), CONNECT_ONESHOT);
+		p_node->connect(SceneStringNames::get_singleton()->ready, callable_mp(this, &MultiplayerSpawner::_node_ready), varray(p_node->get_instance_id()), CONNECT_ONESHOT);
+	}
+}
+
+void MultiplayerSpawner::_node_ready(ObjectID p_id) {
+	get_multiplayer()->object_configuration_add(ObjectDB::get_instance(p_id), this);
+}
+
+void MultiplayerSpawner::_node_exit(ObjectID p_id) {
+	Node *node = Object::cast_to<Node>(ObjectDB::get_instance(p_id));
+	ERR_FAIL_COND(!node);
+	if (tracked_nodes.has(p_id)) {
+		tracked_nodes.erase(p_id);
+		get_multiplayer()->object_configuration_remove(node, this);
+	}
+}
+
+int MultiplayerSpawner::find_spawnable_scene_index_from_path(const String &p_scene) const {
+	for (uint32_t i = 0; i < spawnable_scenes.size(); i++) {
+		if (spawnable_scenes[i].path == p_scene) {
+			return i;
+		}
+	}
+	return INVALID_ID;
+}
+
+int MultiplayerSpawner::find_spawnable_scene_index_from_object(const ObjectID &p_id) const {
+	const SpawnInfo *info = tracked_nodes.getptr(p_id);
+	return info ? info->id : INVALID_ID;
+}
+
+const Variant MultiplayerSpawner::get_spawn_argument(const ObjectID &p_id) const {
+	const SpawnInfo *info = tracked_nodes.getptr(p_id);
+	return info ? info->args : Variant();
+}
+
+Node *MultiplayerSpawner::instantiate_scene(int p_id) {
+	ERR_FAIL_COND_V_MSG(spawn_limit && spawn_limit <= tracked_nodes.size(), nullptr, "Spawn limit reached!");
+	ERR_FAIL_UNSIGNED_INDEX_V((uint32_t)p_id, spawnable_scenes.size(), nullptr);
+	Ref<PackedScene> scene = spawnable_scenes[p_id].cache;
+	ERR_FAIL_COND_V(scene.is_null(), nullptr);
+	return scene->instantiate();
+}
+
+Node *MultiplayerSpawner::instantiate_custom(const Variant &p_data) {
+	ERR_FAIL_COND_V_MSG(spawn_limit && spawn_limit <= tracked_nodes.size(), nullptr, "Spawn limit reached!");
+	Object *obj = nullptr;
+	Node *node = nullptr;
+	if (GDVIRTUAL_CALL(_spawn_custom, p_data, obj)) {
+		node = Object::cast_to<Node>(obj);
+	}
+	return node;
+}
+
+Node *MultiplayerSpawner::spawn(const Variant &p_data) {
+	ERR_FAIL_COND_V(!is_inside_tree() || !get_multiplayer()->has_multiplayer_peer() || !is_multiplayer_authority(), nullptr);
+	ERR_FAIL_COND_V_MSG(spawn_limit && spawn_limit <= tracked_nodes.size(), nullptr, "Spawn limit reached!");
+	ERR_FAIL_COND_V_MSG(!GDVIRTUAL_IS_OVERRIDDEN(_spawn_custom), nullptr, "Custom spawn requires the '_spawn_custom' virtual method to be implemented via script.");
+
+	Node *parent = get_spawn_node();
+	ERR_FAIL_COND_V_MSG(!parent, nullptr, "Cannot find spawn node.");
+
+	Node *node = instantiate_custom(p_data);
+	ERR_FAIL_COND_V_MSG(!node, nullptr, "The '_spawn_custom' implementation must return a valid Node.");
+
+	_track(node, p_data);
+	parent->add_child(node, true);
+	return node;
+}