Add decentralized cryptographic identity

network/known_player_store.gd

@@ -0,0 +1,119 @@
+class_name KnownPlayerStore
+extends Node
+
+const FORMAT_VERSION: int = 1
+const STORE_PATH: String = "user://known_players.json"
+const TEMP_PATH: String = STORE_PATH + ".tmp"
+const MAX_RECORDS: int = 500
+
+var _records: Dictionary = {}
+var _loaded: bool = false
+var _write_blocked: bool = false
+
+
+func observe(fingerprint: String, display_name: String) -> String:
+	_ensure_loaded()
+	if (
+		not NetworkIdentityCrypto.valid_fingerprint(fingerprint)
+		or not NetworkProfilePreferences.is_valid_display_name(display_name)
+	):
+		return ""
+	var now := int(Time.get_unix_time_from_system())
+	var status := "New identity"
+	var record: Dictionary = _records.get(fingerprint, {})
+	if not record.is_empty():
+		status = "Known player"
+	else:
+		for value: Dictionary in _records.values():
+			if str(value.get("last_known_display_name", "")).nocasecmp_to(display_name) == 0:
+				status = "New identity using a familiar name"
+				break
+		record = {
+			"fingerprint": fingerprint,
+			"first_seen_unix": now,
+			"locally_verified": false,
+		}
+	record["last_known_display_name"] = display_name
+	record["last_seen_unix"] = now
+	_records[fingerprint] = record
+	_bound_records()
+	_save()
+	return status
+
+
+func get_record(fingerprint: String) -> Dictionary:
+	_ensure_loaded()
+	return Dictionary(_records.get(fingerprint, {})).duplicate(true)
+
+
+func identity_status(fingerprint: String, display_name: String) -> String:
+	_ensure_loaded()
+	var record: Dictionary = _records.get(fingerprint, {})
+	if not record.is_empty():
+		return "Known player"
+	for value: Dictionary in _records.values():
+		if str(value.get("last_known_display_name", "")).nocasecmp_to(display_name) == 0:
+			return "New identity using a familiar name"
+	return "New identity"
+
+
+func _ensure_loaded() -> void:
+	if _loaded:
+		return
+	_loaded = true
+	if not FileAccess.file_exists(STORE_PATH):
+		return
+	var file := FileAccess.open(STORE_PATH, FileAccess.READ)
+	if file == null:
+		return
+	var json := JSON.new()
+	if json.parse(file.get_as_text()) != OK or typeof(json.data) != TYPE_DICTIONARY:
+		return
+	var data: Dictionary = json.data
+	if data.get("format_version") != FORMAT_VERSION:
+		_write_blocked = true
+		return
+	if typeof(data.get("records")) != TYPE_ARRAY:
+		return
+	for value: Variant in data["records"]:
+		if typeof(value) != TYPE_DICTIONARY:
+			continue
+		var record: Dictionary = value
+		var fingerprint := str(record.get("fingerprint", ""))
+		if NetworkIdentityCrypto.valid_fingerprint(fingerprint):
+			_records[fingerprint] = record.duplicate(true)
+
+
+func _save() -> bool:
+	if _write_blocked:
+		return false
+	var file := FileAccess.open(TEMP_PATH, FileAccess.WRITE)
+	if file == null:
+		return false
+	file.store_string(JSON.stringify({
+		"format_version": FORMAT_VERSION,
+		"records": _records.values(),
+	}, "\t"))
+	file.flush()
+	var ok := file.get_error() == OK
+	file.close()
+	if not ok:
+		return false
+	if FileAccess.file_exists(STORE_PATH):
+		DirAccess.remove_absolute(ProjectSettings.globalize_path(STORE_PATH))
+	return DirAccess.rename_absolute(
+		ProjectSettings.globalize_path(TEMP_PATH),
+		ProjectSettings.globalize_path(STORE_PATH),
+	) == OK
+
+
+func _bound_records() -> void:
+	while _records.size() > MAX_RECORDS:
+		var oldest_key := ""
+		var oldest_time := 9223372036854775807
+		for key: String in _records:
+			var seen := int(_records[key].get("last_seen_unix", 0))
+			if seen < oldest_time:
+				oldest_time = seen
+				oldest_key = key
+		_records.erase(oldest_key)