import base64 import math import RNS from cryptography.fernet import Fernet from cryptography.hazmat.primitives import hashes from cryptography.hazmat.backends import default_backend class Callbacks: def __init__(self): self.link_established = None self.packet = None self.proof_requested = None class Destination: """ A class used to describe endpoints in a Reticulum Network. Destination instances are used both to create outgoing and incoming endpoints. The destination type will decide if encryption, and what type, is used in communication with the endpoint. A destination can also announce its presence on the network, which will also distribute necessary keys for encrypted communication with it. :param identity: An instance of :ref:`RNS.Identity`. Can hold only public keys for an outgoing destination, or holding private keys for an ingoing. :param direction: ``RNS.Destination.IN`` or ``RNS.Destination.OUT`` :param type: ``RNS.Destination.SINGLE``, ``RNS.Destination.GROUP`` or ``RNS.Destination.PLAIN``. :param app_name: A string specifying the app name. :param \*aspects: Any non-zero number of string arguments. """ # Constants SINGLE = 0x00 GROUP = 0x01 PLAIN = 0x02 LINK = 0x03 types = [SINGLE, GROUP, PLAIN, LINK] PROVE_NONE = 0x21 PROVE_APP = 0x22 PROVE_ALL = 0x23 proof_strategies = [PROVE_NONE, PROVE_APP, PROVE_ALL] ALLOW_NONE = 0x00 ALLOW_ALL = 0x01 ALLOW_LIST = 0x02 request_policies = [ALLOW_NONE, ALLOW_ALL, ALLOW_LIST] IN = 0x11; OUT = 0x12; directions = [IN, OUT] @staticmethod def full_name(app_name, *aspects): """ :returns: A string containing the full human-readable name of the destination, for an app_name and a number of aspects. """ # Check input values and build name string if "." in app_name: raise ValueError("Dots can't be used in app names") name = app_name for aspect in aspects: if "." in aspect: raise ValueError("Dots can't be used in aspects") name = name + "." + aspect return name @staticmethod def hash(app_name, *aspects): """ :returns: A destination name in adressable hash form, for an app_name and a number of aspects. """ name = Destination.full_name(app_name, *aspects) # Create a digest for the destination digest = hashes.Hash(hashes.SHA256(), backend=default_backend()) digest.update(name.encode("UTF-8")) return digest.finalize()[:10] @staticmethod def app_and_aspects_from_name(full_name): """ :returns: A tuple containing the app name and a list of aspects, for a full-name string. """ components = full_name.split(".") return (components[0], components[1:]) @staticmethod def hash_from_name_and_identity(full_name, identity): """ :returns: A destination name in adressable hash form, for a full name string and Identity instance. """ app_name, aspects = Destination.app_and_aspects_from_name(full_name) aspects.append(identity.hexhash) return Destination.hash(app_name, *aspects) def __init__(self, identity, direction, type, app_name, *aspects): # Check input values and build name string if "." in app_name: raise ValueError("Dots can't be used in app names") if not type in Destination.types: raise ValueError("Unknown destination type") if not direction in Destination.directions: raise ValueError("Unknown destination direction") self.callbacks = Callbacks() self.request_handlers = {} self.type = type self.direction = direction self.proof_strategy = Destination.PROVE_NONE self.mtu = 0 self.links = [] if identity != None and type == Destination.SINGLE: aspects = aspects+(identity.hexhash,) if identity == None and direction == Destination.IN and self.type != Destination.PLAIN: identity = RNS.Identity() aspects = aspects+(identity.hexhash,) self.identity = identity self.name = Destination.full_name(app_name, *aspects) self.hash = Destination.hash(app_name, *aspects) self.hexhash = self.hash.hex() self.default_app_data = None self.callback = None self.proofcallback = None RNS.Transport.register_destination(self) def __str__(self): """ :returns: A human-readable representation of the destination including addressable hash and full name. """ return "<"+self.name+"/"+self.hexhash+">" def announce(self, app_data=None, path_response=False): """ Creates an announce packet for this destination and broadcasts it on all relevant interfaces. Application specific data can be added to the announce. :param app_data: *bytes* containing the app_data. :param path_response: Internal flag used by :ref:`RNS.Transport`. Ignore. """ destination_hash = self.hash random_hash = RNS.Identity.get_random_hash() if app_data == None and self.default_app_data != None: if isinstance(self.default_app_data, bytes): app_data = self.default_app_data elif callable(self.default_app_data): returned_app_data = self.default_app_data() if isinstance(returned_app_data, bytes): app_data = returned_app_data signed_data = self.hash+self.identity.get_public_key()+random_hash if app_data != None: signed_data += app_data signature = self.identity.sign(signed_data) announce_data = self.identity.get_public_key()+random_hash+signature if app_data != None: announce_data += app_data if path_response: announce_context = RNS.Packet.PATH_RESPONSE else: announce_context = RNS.Packet.NONE RNS.Packet(self, announce_data, RNS.Packet.ANNOUNCE, context = announce_context).send() def set_link_established_callback(self, callback): """ Registers a function to be called when a link has been established to this destination. :param callback: A function or method to be called. """ self.callbacks.link_established = callback def set_packet_callback(self, callback): """ Registers a function to be called when a packet has been received by this destination. :param callback: A function or method to be called. """ self.callbacks.packet = callback def set_proof_requested_callback(self, callback): """ Registers a function to be called when a proof has been requested for a packet sent to this destination. Allows control over when and if proofs should be returned for received packets. :param callback: A function or method to be called. The callback must return one of True or False. If the callback returns True, a proof will be sent. If it returns False, a proof will not be sent. """ self.callbacks.proof_requested = callback def set_proof_strategy(self, proof_strategy): """ Sets the destinations proof strategy. :param proof_strategy: One of ``RNS.Destination.PROVE_NONE``, ``RNS.Destination.PROVE_ALL`` or ``RNS.Destination.PROVE_APP``. If ``RNS.Destination.PROVE_APP`` is set, the `proof_requested_callback` will be called to determine whether a proof should be sent or not. """ if not proof_strategy in Destination.proof_strategies: raise TypeError("Unsupported proof strategy") else: self.proof_strategy = proof_strategy def register_request_handler(self, path, response_generator = None, allow = ALLOW_NONE, allowed_list = None): """ Registers a request handler. :param path: The path for the request handler to be registered. :param response_generator: A function or method with the signature *response_generator(path, data, request_id, remote_identity_hash, requested_at)* to be called. Whatever this funcion returns will be sent as a response to the requester. If the function returns ``None``, no response will be sent. :param allow: One of ``RNS.Destination.ALLOW_NONE``, ``RNS.Destination.ALLOW_ALL`` or ``RNS.Destination.ALLOW_LIST``. If ``RNS.Destination.ALLOW_LIST`` is set, the request handler will only respond to requests for identified peers in the supplied list. :param allowed_list: A list of *bytes-like* :ref:`RNS.Identity` hashes. :raises: ``ValueError`` if any of the supplied arguments are invalid. """ if path == None or path == "": raise ValueError("Invalid path specified") elif not callable(response_generator): raise ValueError("Invalid response generator specified") elif not allow in Destination.request_policies: raise ValueError("Invalid request policy") else: path_hash = RNS.Identity.truncated_hash(path.encode("utf-8")) request_handler = [path, response_generator, allow, allowed_list] self.request_handlers[path_hash] = request_handler def deregister_request_handler(self, path): """ Deregisters a request handler. :param path: The path for the request handler to be deregistered. :returns: True if the handler was deregistered, otherwise False. """ path_hash = RNS.Identity.truncated_hash(path.encode("utf-8")) if path_hash in self.request_handlers: self.request_handlers.pop(path_hash) return True else: return False def receive(self, packet): if packet.packet_type == RNS.Packet.LINKREQUEST: plaintext = packet.data self.incoming_link_request(plaintext, packet) else: plaintext = self.decrypt(packet.data) if plaintext != None: if packet.packet_type == RNS.Packet.DATA: if self.callbacks.packet != None: self.callbacks.packet(plaintext, packet) def incoming_link_request(self, data, packet): link = RNS.Link.validate_request(self, data, packet) if link != None: self.links.append(link) def create_keys(self): """ For a ``RNS.Destination.GROUP`` type destination, creates a new symmetric key. :raises: ``TypeError`` if called on an incompatible type of destination. """ if self.type == Destination.PLAIN: raise TypeError("A plain destination does not hold any keys") if self.type == Destination.SINGLE: raise TypeError("A single destination holds keys through an Identity instance") if self.type == Destination.GROUP: self.prv_bytes = base64.urlsafe_b64decode(Fernet.generate_key()) self.prv = Fernet(base64.urlsafe_b64encode(self.prv_bytes)) def get_private_key(self): """ For a ``RNS.Destination.GROUP`` type destination, returns the symmetric private key. :raises: ``TypeError`` if called on an incompatible type of destination. """ if self.type == Destination.PLAIN: raise TypeError("A plain destination does not hold any keys") elif self.type == Destination.SINGLE: raise TypeError("A single destination holds keys through an Identity instance") else: return self.prv_bytes def load_private_key(self, key): """ For a ``RNS.Destination.GROUP`` type destination, loads a symmetric private key. :param key: A *bytes-like* containing the symmetric key. :raises: ``TypeError`` if called on an incompatible type of destination. """ if self.type == Destination.PLAIN: raise TypeError("A plain destination does not hold any keys") if self.type == Destination.SINGLE: raise TypeError("A single destination holds keys through an Identity instance") if self.type == Destination.GROUP: self.prv_bytes = key self.prv = Fernet(base64.urlsafe_b64encode(self.prv_bytes)) def load_public_key(self, key): if self.type != Destination.SINGLE: raise TypeError("Only the \"single\" destination type can hold a public key") else: raise TypeError("A single destination holds keys through an Identity instance") def encrypt(self, plaintext): """ Encrypts information for ``RNS.Destination.SINGLE`` or ``RNS.Destination.GROUP`` type destination. :param plaintext: A *bytes-like* containing the plaintext to be encrypted. :raises: ``ValueError`` if destination does not hold a necessary key for encryption. """ if self.type == Destination.PLAIN: return plaintext if self.type == Destination.SINGLE and self.identity != None: return self.identity.encrypt(plaintext) if self.type == Destination.GROUP: if hasattr(self, "prv") and self.prv != None: try: return base64.urlsafe_b64decode(self.prv.encrypt(plaintext)) except Exception as e: RNS.log("The GROUP destination could not encrypt data", RNS.LOG_ERROR) RNS.log("The contained exception was: "+str(e), RNS.LOG_ERROR) else: raise ValueError("No private key held by GROUP destination. Did you create or load one?") def decrypt(self, ciphertext): """ Decrypts information for ``RNS.Destination.SINGLE`` or ``RNS.Destination.GROUP`` type destination. :param ciphertext: *Bytes* containing the ciphertext to be decrypted. :raises: ``ValueError`` if destination does not hold a necessary key for decryption. """ if self.type == Destination.PLAIN: return ciphertext if self.type == Destination.SINGLE and self.identity != None: return self.identity.decrypt(ciphertext) if self.type == Destination.GROUP: if hasattr(self, "prv") and self.prv != None: try: return self.prv.decrypt(base64.urlsafe_b64encode(ciphertext)) except Exception as e: RNS.log("The GROUP destination could not decrypt data", RNS.LOG_ERROR) RNS.log("The contained exception was: "+str(e), RNS.LOG_ERROR) else: raise ValueError("No private key held by GROUP destination. Did you create or load one?") def sign(self, message): """ Signs information for ``RNS.Destination.SINGLE`` type destination. :param message: *Bytes* containing the message to be signed. :returns: A *bytes-like* containing the message signature, or *None* if the destination could not sign the message. """ if self.type == Destination.SINGLE and self.identity != None: return self.identity.sign(message) else: return None def set_default_app_data(self, app_data=None): """ Sets the default app_data for the destination. If set, the default app_data will be included in every announce sent by the destination, unless other app_data is specified in the *announce* method. :param app_data: A *bytes-like* containing the default app_data, or a *callable* returning a *bytes-like* containing the app_data. """ self.default_app_data = app_data def clear_default_app_data(self): """ Clears default app_data previously set for the destination. """ self.set_default_app_data(app_data=None)