godot/modules/multiplayer/scene_cache_interface.cpp

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/*  scene_cache_interface.cpp                                            */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
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#include "scene_cache_interface.h"

#include "core/io/marshalls.h"
#include "scene/main/node.h"
#include "scene/main/window.h"

#include "scene_multiplayer.h"

void SceneCacheInterface::on_peer_change(int p_id, bool p_connected) {
	if (p_connected) {
		path_get_cache.insert(p_id, PathGetCache());
	} else {
		// Cleanup get cache.
		path_get_cache.erase(p_id);
		// Cleanup sent cache.
		// Some refactoring is needed to make this faster and do paths GC.
		for (const KeyValue<NodePath, PathSentCache> &E : path_send_cache) {
			PathSentCache *psc = path_send_cache.getptr(E.key);
			psc->confirmed_peers.erase(p_id);
		}
	}
}

void SceneCacheInterface::process_simplify_path(int p_from, const uint8_t *p_packet, int p_packet_len) {
	Node *root_node = SceneTree::get_singleton()->get_root()->get_node(multiplayer->get_root_path());
	ERR_FAIL_COND(!root_node);
	ERR_FAIL_COND_MSG(p_packet_len < 38, "Invalid packet received. Size too small.");
	int ofs = 1;

	String methods_md5;
	methods_md5.parse_utf8((const char *)(p_packet + ofs), 32);
	ofs += 33;

	int id = decode_uint32(&p_packet[ofs]);
	ofs += 4;

	String paths;
	paths.parse_utf8((const char *)(p_packet + ofs), p_packet_len - ofs);

	NodePath path = paths;

	if (!path_get_cache.has(p_from)) {
		path_get_cache[p_from] = PathGetCache();
	}

	Node *node = root_node->get_node(path);
	ERR_FAIL_COND(node == nullptr);
	const bool valid_rpc_checksum = multiplayer->get_rpc_md5(node) == methods_md5;
	if (valid_rpc_checksum == false) {
		ERR_PRINT("The rpc node checksum failed. Make sure to have the same methods on both nodes. Node path: " + path);
	}

	PathGetCache::NodeInfo ni;
	ni.path = path;

	path_get_cache[p_from].nodes[id] = ni;

	// Encode path to send ack.
	CharString pname = String(path).utf8();
	int len = encode_cstring(pname.get_data(), nullptr);

	Vector<uint8_t> packet;

	packet.resize(1 + 1 + len);
	packet.write[0] = SceneMultiplayer::NETWORK_COMMAND_CONFIRM_PATH;
	packet.write[1] = valid_rpc_checksum;
	encode_cstring(pname.get_data(), &packet.write[2]);

	Ref<MultiplayerPeer> multiplayer_peer = multiplayer->get_multiplayer_peer();
	ERR_FAIL_COND(multiplayer_peer.is_null());

	multiplayer_peer->set_transfer_channel(0);
	multiplayer_peer->set_transfer_mode(MultiplayerPeer::TRANSFER_MODE_RELIABLE);
	multiplayer->send_command(p_from, packet.ptr(), packet.size());
}

void SceneCacheInterface::process_confirm_path(int p_from, const uint8_t *p_packet, int p_packet_len) {
	ERR_FAIL_COND_MSG(p_packet_len < 3, "Invalid packet received. Size too small.");

	const bool valid_rpc_checksum = p_packet[1];

	String paths;
	paths.parse_utf8((const char *)&p_packet[2], p_packet_len - 2);

	NodePath path = paths;

	if (valid_rpc_checksum == false) {
		ERR_PRINT("The rpc node checksum failed. Make sure to have the same methods on both nodes. Node path: " + path);
	}

	PathSentCache *psc = path_send_cache.getptr(path);
	ERR_FAIL_COND_MSG(!psc, "Invalid packet received. Tries to confirm a path which was not found in cache.");

	HashMap<int, bool>::Iterator E = psc->confirmed_peers.find(p_from);
	ERR_FAIL_COND_MSG(!E, "Invalid packet received. Source peer was not found in cache for the given path.");
	E->value = true;
}

Error SceneCacheInterface::_send_confirm_path(Node *p_node, NodePath p_path, PathSentCache *psc, const List<int> &p_peers) {
	// Encode function name.
	const CharString path = String(p_path).utf8();
	const int path_len = encode_cstring(path.get_data(), nullptr);

	// Extract MD5 from rpc methods list.
	const String methods_md5 = multiplayer->get_rpc_md5(p_node);
	const int methods_md5_len = 33; // 32 + 1 for the `0` that is added by the encoder.

	Vector<uint8_t> packet;
	packet.resize(1 + 4 + path_len + methods_md5_len);
	int ofs = 0;

	packet.write[ofs] = SceneMultiplayer::NETWORK_COMMAND_SIMPLIFY_PATH;
	ofs += 1;

	ofs += encode_cstring(methods_md5.utf8().get_data(), &packet.write[ofs]);

	ofs += encode_uint32(psc->id, &packet.write[ofs]);

	ofs += encode_cstring(path.get_data(), &packet.write[ofs]);

	Ref<MultiplayerPeer> multiplayer_peer = multiplayer->get_multiplayer_peer();
	ERR_FAIL_COND_V(multiplayer_peer.is_null(), ERR_BUG);

	Error err = OK;
	for (int peer_id : p_peers) {
		multiplayer_peer->set_transfer_channel(0);
		multiplayer_peer->set_transfer_mode(MultiplayerPeer::TRANSFER_MODE_RELIABLE);
		err = multiplayer->send_command(peer_id, packet.ptr(), packet.size());
		ERR_FAIL_COND_V(err != OK, err);
		// Insert into confirmed, but as false since it was not confirmed.
		psc->confirmed_peers.insert(peer_id, false);
	}
	return err;
}

bool SceneCacheInterface::is_cache_confirmed(NodePath p_path, int p_peer) {
	const PathSentCache *psc = path_send_cache.getptr(p_path);
	ERR_FAIL_COND_V(!psc, false);
	HashMap<int, bool>::ConstIterator F = psc->confirmed_peers.find(p_peer);
	ERR_FAIL_COND_V(!F, false); // Should never happen.
	return F->value;
}

int SceneCacheInterface::make_object_cache(Object *p_obj) {
	Node *node = Object::cast_to<Node>(p_obj);
	ERR_FAIL_COND_V(!node, -1);
	NodePath for_path = multiplayer->get_root_path().rel_path_to(node->get_path());
	// See if the path is cached.
	PathSentCache *psc = path_send_cache.getptr(for_path);
	if (!psc) {
		// Path is not cached, create.
		path_send_cache[for_path] = PathSentCache();
		psc = path_send_cache.getptr(for_path);
		psc->id = last_send_cache_id++;
	}
	return psc->id;
}

bool SceneCacheInterface::send_object_cache(Object *p_obj, int p_peer_id, int &r_id) {
	Node *node = Object::cast_to<Node>(p_obj);
	ERR_FAIL_COND_V(!node, false);

	r_id = make_object_cache(p_obj);
	ERR_FAIL_COND_V(r_id < 0, false);
	NodePath for_path = multiplayer->get_root_path().rel_path_to(node->get_path());
	PathSentCache *psc = path_send_cache.getptr(for_path);

	bool has_all_peers = true;
	List<int> peers_to_add; // If one is missing, take note to add it.

	if (p_peer_id > 0) {
		// Fast single peer check.
		HashMap<int, bool>::Iterator F = psc->confirmed_peers.find(p_peer_id);
		if (!F) {
			peers_to_add.push_back(p_peer_id); // Need to also be notified.
			has_all_peers = false;
		} else if (!F->value) {
			has_all_peers = false;
		}
	} else {
		// Long and painful.
		for (const int &E : multiplayer->get_connected_peers()) {
			if (p_peer_id < 0 && E == -p_peer_id) {
				continue; // Continue, excluded.
			}

			HashMap<int, bool>::Iterator F = psc->confirmed_peers.find(E);
			if (!F) {
				peers_to_add.push_back(E); // Need to also be notified.
				has_all_peers = false;
			} else if (!F->value) {
				has_all_peers = false;
			}
		}
	}

	if (peers_to_add.size()) {
		_send_confirm_path(node, for_path, psc, peers_to_add);
	}

	return has_all_peers;
}

Object *SceneCacheInterface::get_cached_object(int p_from, uint32_t p_cache_id) {
	Node *root_node = SceneTree::get_singleton()->get_root()->get_node(multiplayer->get_root_path());
	ERR_FAIL_COND_V(!root_node, nullptr);
	HashMap<int, PathGetCache>::Iterator E = path_get_cache.find(p_from);
	ERR_FAIL_COND_V_MSG(!E, nullptr, vformat("No cache found for peer %d.", p_from));

	HashMap<int, PathGetCache::NodeInfo>::Iterator F = E->value.nodes.find(p_cache_id);
	ERR_FAIL_COND_V_MSG(!F, nullptr, vformat("ID %d not found in cache of peer %d.", p_cache_id, p_from));

	PathGetCache::NodeInfo *ni = &F->value;
	Node *node = root_node->get_node(ni->path);
	if (!node) {
		ERR_PRINT("Failed to get cached path: " + String(ni->path) + ".");
	}
	return node;
}

void SceneCacheInterface::clear() {
	path_get_cache.clear();
	path_send_cache.clear();
	last_send_cache_id = 1;
}