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Reticulum/RNS/Link.py

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# MIT License
#
# Copyright (c) 2016-2023 Mark Qvist / unsigned.io and contributors.
#
# 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.
from RNS.Cryptography import X25519PrivateKey, X25519PublicKey, Ed25519PrivateKey, Ed25519PublicKey
from RNS.Cryptography import Fernet
from RNS.Channel import Channel, LinkChannelOutlet
from time import sleep
from .vendor import umsgpack as umsgpack
import threading
import inspect
import math
import time
import RNS
class LinkCallbacks:
def __init__(self):
self.link_established = None
self.link_closed = None
self.packet = None
self.resource = None
self.resource_started = None
self.resource_concluded = None
self.remote_identified = None
class Link:
"""
This class is used to establish and manage links to other peers. When a
link instance is created, Reticulum will attempt to establish verified
and encrypted connectivity with the specified destination.
:param destination: A :ref:`RNS.Destination<api-destination>` instance which to establish a link to.
:param established_callback: An optional function or method with the signature *callback(link)* to be called when the link has been established.
:param closed_callback: An optional function or method with the signature *callback(link)* to be called when the link is closed.
"""
CURVE = RNS.Identity.CURVE
"""
The curve used for Elliptic Curve DH key exchanges
"""
ECPUBSIZE = 32+32
KEYSIZE = 32
MDU = math.floor((RNS.Reticulum.MTU-RNS.Reticulum.IFAC_MIN_SIZE-RNS.Reticulum.HEADER_MINSIZE-RNS.Identity.FERNET_OVERHEAD)/RNS.Identity.AES128_BLOCKSIZE)*RNS.Identity.AES128_BLOCKSIZE - 1
ESTABLISHMENT_TIMEOUT_PER_HOP = RNS.Reticulum.DEFAULT_PER_HOP_TIMEOUT
"""
Timeout for link establishment in seconds per hop to destination.
"""
TRAFFIC_TIMEOUT_FACTOR = 6
KEEPALIVE_TIMEOUT_FACTOR = 4
"""
RTT timeout factor used in link timeout calculation.
"""
STALE_GRACE = 2
"""
Grace period in seconds used in link timeout calculation.
"""
KEEPALIVE = 360
"""
Interval for sending keep-alive packets on established links in seconds.
"""
STALE_TIME = 2*KEEPALIVE
"""
If no traffic or keep-alive packets are received within this period, the
link will be marked as stale, and a final keep-alive packet will be sent.
If after this no traffic or keep-alive packets are received within ``RTT`` *
``KEEPALIVE_TIMEOUT_FACTOR`` + ``STALE_GRACE``, the link is considered timed out,
and will be torn down.
"""
PENDING = 0x00
HANDSHAKE = 0x01
ACTIVE = 0x02
STALE = 0x03
CLOSED = 0x04
TIMEOUT = 0x01
INITIATOR_CLOSED = 0x02
DESTINATION_CLOSED = 0x03
ACCEPT_NONE = 0x00
ACCEPT_APP = 0x01
ACCEPT_ALL = 0x02
resource_strategies = [ACCEPT_NONE, ACCEPT_APP, ACCEPT_ALL]
@staticmethod
def validate_request(owner, data, packet):
if len(data) == (Link.ECPUBSIZE):
try:
link = Link(owner = owner, peer_pub_bytes=data[:Link.ECPUBSIZE//2], peer_sig_pub_bytes=data[Link.ECPUBSIZE//2:Link.ECPUBSIZE])
link.set_link_id(packet)
link.destination = packet.destination
link.establishment_timeout = Link.ESTABLISHMENT_TIMEOUT_PER_HOP * max(1, packet.hops)
link.establishment_cost += len(packet.raw)
RNS.log("Validating link request "+RNS.prettyhexrep(link.link_id), RNS.LOG_VERBOSE)
link.handshake()
link.attached_interface = packet.receiving_interface
link.prove()
link.request_time = time.time()
RNS.Transport.register_link(link)
link.last_inbound = time.time()
link.start_watchdog()
RNS.log("Incoming link request "+str(link)+" accepted", RNS.LOG_VERBOSE)
return link
except Exception as e:
RNS.log("Validating link request failed", RNS.LOG_VERBOSE)
RNS.log("exc: "+str(e))
return None
else:
RNS.log("Invalid link request payload size, dropping request", RNS.LOG_VERBOSE)
return None
def __init__(self, destination=None, established_callback = None, closed_callback = None, owner=None, peer_pub_bytes = None, peer_sig_pub_bytes = None):
if destination != None and destination.type != RNS.Destination.SINGLE:
raise TypeError("Links can only be established to the \"single\" destination type")
self.rtt = None
self.establishment_cost = 0
self.callbacks = LinkCallbacks()
self.resource_strategy = Link.ACCEPT_NONE
self.outgoing_resources = []
self.incoming_resources = []
self.pending_requests = []
self.last_inbound = 0
self.last_outbound = 0
self.last_proof = 0
self.tx = 0
self.rx = 0
self.txbytes = 0
self.rxbytes = 0
self.rssi = None
self.snr = None
self.q = None
self.traffic_timeout_factor = Link.TRAFFIC_TIMEOUT_FACTOR
self.keepalive_timeout_factor = Link.KEEPALIVE_TIMEOUT_FACTOR
self.keepalive = Link.KEEPALIVE
self.stale_time = Link.STALE_TIME
self.watchdog_lock = False
self.status = Link.PENDING
self.activated_at = None
self.type = RNS.Destination.LINK
self.owner = owner
self.destination = destination
self.attached_interface = None
self.__remote_identity = None
self._channel = None
if self.destination == None:
self.initiator = False
self.prv = X25519PrivateKey.generate()
self.sig_prv = self.owner.identity.sig_prv
else:
self.initiator = True
self.establishment_timeout = Link.ESTABLISHMENT_TIMEOUT_PER_HOP * max(1, RNS.Transport.hops_to(destination.hash))
self.prv = X25519PrivateKey.generate()
self.sig_prv = Ed25519PrivateKey.generate()
self.fernet = None
self.pub = self.prv.public_key()
self.pub_bytes = self.pub.public_bytes()
self.sig_pub = self.sig_prv.public_key()
self.sig_pub_bytes = self.sig_pub.public_bytes()
if peer_pub_bytes == None:
self.peer_pub = None
self.peer_pub_bytes = None
else:
self.load_peer(peer_pub_bytes, peer_sig_pub_bytes)
if established_callback != None:
self.set_link_established_callback(established_callback)
if closed_callback != None:
self.set_link_closed_callback(closed_callback)
if (self.initiator):
self.request_data = self.pub_bytes+self.sig_pub_bytes
self.packet = RNS.Packet(destination, self.request_data, packet_type=RNS.Packet.LINKREQUEST)
self.packet.pack()
self.establishment_cost += len(self.packet.raw)
self.set_link_id(self.packet)
RNS.Transport.register_link(self)
self.request_time = time.time()
self.start_watchdog()
self.packet.send()
self.had_outbound()
RNS.log("Link request "+RNS.prettyhexrep(self.link_id)+" sent to "+str(self.destination), RNS.LOG_DEBUG)
def load_peer(self, peer_pub_bytes, peer_sig_pub_bytes):
self.peer_pub_bytes = peer_pub_bytes
self.peer_pub = X25519PublicKey.from_public_bytes(self.peer_pub_bytes)
self.peer_sig_pub_bytes = peer_sig_pub_bytes
self.peer_sig_pub = Ed25519PublicKey.from_public_bytes(self.peer_sig_pub_bytes)
if not hasattr(self.peer_pub, "curve"):
self.peer_pub.curve = Link.CURVE
def set_link_id(self, packet):
self.link_id = packet.getTruncatedHash()
self.hash = self.link_id
def handshake(self):
if self.status == Link.PENDING and self.prv != None:
self.status = Link.HANDSHAKE
self.shared_key = self.prv.exchange(self.peer_pub)
self.derived_key = RNS.Cryptography.hkdf(
length=32,
derive_from=self.shared_key,
salt=self.get_salt(),
context=self.get_context(),
)
else:
RNS.log("Handshake attempt on "+str(self)+" with invalid state "+str(self.status), RNS.LOG_ERROR)
def prove(self):
signed_data = self.link_id+self.pub_bytes+self.sig_pub_bytes
signature = self.owner.identity.sign(signed_data)
proof_data = signature+self.pub_bytes
proof = RNS.Packet(self, proof_data, packet_type=RNS.Packet.PROOF, context=RNS.Packet.LRPROOF)
proof.send()
self.establishment_cost += len(proof.raw)
self.had_outbound()
def prove_packet(self, packet):
signature = self.sign(packet.packet_hash)
# TODO: Hardcoded as explicit proof for now
# if RNS.Reticulum.should_use_implicit_proof():
# proof_data = signature
# else:
# proof_data = packet.packet_hash + signature
proof_data = packet.packet_hash + signature
proof = RNS.Packet(self, proof_data, RNS.Packet.PROOF)
proof.send()
self.had_outbound()
def validate_proof(self, packet):
try:
if self.status == Link.PENDING:
if self.initiator and len(packet.data) == RNS.Identity.SIGLENGTH//8+Link.ECPUBSIZE//2:
peer_pub_bytes = packet.data[RNS.Identity.SIGLENGTH//8:RNS.Identity.SIGLENGTH//8+Link.ECPUBSIZE//2]
peer_sig_pub_bytes = self.destination.identity.get_public_key()[Link.ECPUBSIZE//2:Link.ECPUBSIZE]
self.load_peer(peer_pub_bytes, peer_sig_pub_bytes)
self.handshake()
self.establishment_cost += len(packet.raw)
signed_data = self.link_id+self.peer_pub_bytes+self.peer_sig_pub_bytes
signature = packet.data[:RNS.Identity.SIGLENGTH//8]
if self.destination.identity.validate(signature, signed_data):
if self.status != Link.HANDSHAKE:
raise IOError("Invalid link state for proof validation: "+str(self.status))
self.rtt = time.time() - self.request_time
self.attached_interface = packet.receiving_interface
self.__remote_identity = self.destination.identity
self.status = Link.ACTIVE
self.activated_at = time.time()
self.last_proof = self.activated_at
RNS.Transport.activate_link(self)
RNS.log("Link "+str(self)+" established with "+str(self.destination)+", RTT is "+str(round(self.rtt, 3))+"s", RNS.LOG_VERBOSE)
if self.rtt != None and self.establishment_cost != None and self.rtt > 0 and self.establishment_cost > 0:
self.establishment_rate = self.establishment_cost/self.rtt
rtt_data = umsgpack.packb(self.rtt)
rtt_packet = RNS.Packet(self, rtt_data, context=RNS.Packet.LRRTT)
rtt_packet.send()
self.had_outbound()
if self.callbacks.link_established != None:
thread = threading.Thread(target=self.callbacks.link_established, args=(self,))
thread.daemon = True
thread.start()
else:
RNS.log("Invalid link proof signature received by "+str(self)+". Ignoring.", RNS.LOG_DEBUG)
except Exception as e:
self.status = Link.CLOSED
RNS.log("An error ocurred while validating link request proof on "+str(self)+".", RNS.LOG_ERROR)
RNS.log("The contained exception was: "+str(e), RNS.LOG_ERROR)
def identify(self, identity):
"""
Identifies the initiator of the link to the remote peer. This can only happen
once the link has been established, and is carried out over the encrypted link.
The identity is only revealed to the remote peer, and initiator anonymity is
thus preserved. This method can be used for authentication.
:param identity: An RNS.Identity instance to identify as.
"""
if self.initiator and self.status == Link.ACTIVE:
signed_data = self.link_id + identity.get_public_key()
signature = identity.sign(signed_data)
proof_data = identity.get_public_key() + signature
proof = RNS.Packet(self, proof_data, RNS.Packet.DATA, context = RNS.Packet.LINKIDENTIFY)
proof.send()
self.had_outbound()
def request(self, path, data = None, response_callback = None, failed_callback = None, progress_callback = None, timeout = None):
"""
Sends a request to the remote peer.
:param path: The request path.
:param response_callback: An optional function or method with the signature *response_callback(request_receipt)* to be called when a response is received. See the :ref:`Request Example<example-request>` for more info.
:param failed_callback: An optional function or method with the signature *failed_callback(request_receipt)* to be called when a request fails. See the :ref:`Request Example<example-request>` for more info.
:param progress_callback: An optional function or method with the signature *progress_callback(request_receipt)* to be called when progress is made receiving the response. Progress can be accessed as a float between 0.0 and 1.0 by the *request_receipt.progress* property.
:param timeout: An optional timeout in seconds for the request. If *None* is supplied it will be calculated based on link RTT.
:returns: A :ref:`RNS.RequestReceipt<api-requestreceipt>` instance if the request was sent, or *False* if it was not.
"""
request_path_hash = RNS.Identity.truncated_hash(path.encode("utf-8"))
unpacked_request = [time.time(), request_path_hash, data]
packed_request = umsgpack.packb(unpacked_request)
if timeout == None:
timeout = self.rtt * self.traffic_timeout_factor + RNS.Resource.RESPONSE_MAX_GRACE_TIME/4.0
if len(packed_request) <= Link.MDU:
request_packet = RNS.Packet(self, packed_request, RNS.Packet.DATA, context = RNS.Packet.REQUEST)
packet_receipt = request_packet.send()
if packet_receipt == False:
return False
else:
packet_receipt.set_timeout(timeout)
return RequestReceipt(
self,
packet_receipt = packet_receipt,
response_callback = response_callback,
failed_callback = failed_callback,
progress_callback = progress_callback,
timeout = timeout,
request_size = len(packed_request),
)
else:
request_id = RNS.Identity.truncated_hash(packed_request)
RNS.log("Sending request "+RNS.prettyhexrep(request_id)+" as resource.", RNS.LOG_DEBUG)
request_resource = RNS.Resource(packed_request, self, request_id = request_id, is_response = False, timeout = timeout)
return RequestReceipt(
self,
resource = request_resource,
response_callback = response_callback,
failed_callback = failed_callback,
progress_callback = progress_callback,
timeout = timeout,
request_size = len(packed_request),
)
def rtt_packet(self, packet):
try:
measured_rtt = time.time() - self.request_time
plaintext = self.decrypt(packet.data)
rtt = umsgpack.unpackb(plaintext)
self.rtt = max(measured_rtt, rtt)
self.status = Link.ACTIVE
self.activated_at = time.time()
if self.rtt != None and self.establishment_cost != None and self.rtt > 0 and self.establishment_cost > 0:
self.establishment_rate = self.establishment_cost/self.rtt
try:
if self.owner.callbacks.link_established != None:
self.owner.callbacks.link_established(self)
except Exception as e:
RNS.log("Error occurred in external link establishment callback. The contained exception was: "+str(e), RNS.LOG_ERROR)
except Exception as e:
RNS.log("Error occurred while processing RTT packet, tearing down link. The contained exception was: "+str(e), RNS.LOG_ERROR)
self.teardown()
def get_establishment_rate(self):
"""
:returns: The data transfer rate at which the link establishment procedure ocurred, in bits per second.
"""
if self.establishment_rate != None:
return self.establishment_rate*8
else:
return None
def get_salt(self):
return self.link_id
def get_context(self):
return None
def no_inbound_for(self):
"""
:returns: The time in seconds since last inbound packet on the link.
"""
activated_at = self.activated_at if self.activated_at != None else 0
last_inbound = max(self.last_inbound, activated_at)
return time.time() - last_inbound
def no_outbound_for(self):
"""
:returns: The time in seconds since last outbound packet on the link.
"""
return time.time() - self.last_outbound
def inactive_for(self):
"""
:returns: The time in seconds since activity on the link.
"""
return min(self.no_inbound_for(), self.no_outbound_for())
def get_remote_identity(self):
"""
:returns: The identity of the remote peer, if it is known. Calling this method will not query the remote initiator to reveal its identity. Returns ``None`` if the link initiator has not already independently called the ``identify(identity)`` method.
"""
return self.__remote_identity
def had_outbound(self):
self.last_outbound = time.time()
def teardown(self):
"""
Closes the link and purges encryption keys. New keys will
be used if a new link to the same destination is established.
"""
if self.status != Link.PENDING and self.status != Link.CLOSED:
teardown_packet = RNS.Packet(self, self.link_id, context=RNS.Packet.LINKCLOSE)
teardown_packet.send()
self.had_outbound()
self.status = Link.CLOSED
if self.initiator:
self.teardown_reason = Link.INITIATOR_CLOSED
else:
self.teardown_reason = Link.DESTINATION_CLOSED
self.link_closed()
def teardown_packet(self, packet):
try:
plaintext = self.decrypt(packet.data)
if plaintext == self.link_id:
self.status = Link.CLOSED
if self.initiator:
self.teardown_reason = Link.DESTINATION_CLOSED
else:
self.teardown_reason = Link.INITIATOR_CLOSED
self.__update_phy_stats(packet)
self.link_closed()
except Exception as e:
pass
def link_closed(self):
for resource in self.incoming_resources:
resource.cancel()
for resource in self.outgoing_resources:
resource.cancel()
if self._channel:
self._channel._shutdown()
self.prv = None
self.pub = None
self.pub_bytes = None
self.shared_key = None
self.derived_key = None
if self.destination != None:
if self.destination.direction == RNS.Destination.IN:
if self in self.destination.links:
self.destination.links.remove(self)
if self.callbacks.link_closed != None:
try:
self.callbacks.link_closed(self)
except Exception as e:
RNS.log("Error while executing link closed callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
def start_watchdog(self):
thread = threading.Thread(target=self.__watchdog_job)
thread.daemon = True
thread.start()
def __watchdog_job(self):
while not self.status == Link.CLOSED:
while (self.watchdog_lock):
rtt_wait = 0.025
if hasattr(self, "rtt") and self.rtt:
rtt_wait = self.rtt
sleep(max(rtt_wait, 0.025))
if not self.status == Link.CLOSED:
# Link was initiated, but no response
# from destination yet
if self.status == Link.PENDING:
next_check = self.request_time + self.establishment_timeout
sleep_time = next_check - time.time()
if time.time() >= self.request_time + self.establishment_timeout:
RNS.log("Link establishment timed out", RNS.LOG_VERBOSE)
self.status = Link.CLOSED
self.teardown_reason = Link.TIMEOUT
self.link_closed()
sleep_time = 0.001
elif self.status == Link.HANDSHAKE:
next_check = self.request_time + self.establishment_timeout
sleep_time = next_check - time.time()
if time.time() >= self.request_time + self.establishment_timeout:
self.status = Link.CLOSED
self.teardown_reason = Link.TIMEOUT
self.link_closed()
sleep_time = 0.001
if self.initiator:
RNS.log("Timeout waiting for link request proof", RNS.LOG_DEBUG)
else:
RNS.log("Timeout waiting for RTT packet from link initiator", RNS.LOG_DEBUG)
elif self.status == Link.ACTIVE:
activated_at = self.activated_at if self.activated_at != None else 0
last_inbound = max(max(self.last_inbound, self.last_proof), activated_at)
if time.time() >= last_inbound + self.keepalive:
if self.initiator:
self.send_keepalive()
if time.time() >= last_inbound + self.stale_time:
sleep_time = self.rtt * self.keepalive_timeout_factor + Link.STALE_GRACE
self.status = Link.STALE
else:
sleep_time = self.keepalive
else:
sleep_time = (last_inbound + self.keepalive) - time.time()
elif self.status == Link.STALE:
sleep_time = 0.001
self.status = Link.CLOSED
self.teardown_reason = Link.TIMEOUT
self.link_closed()
if sleep_time == 0:
RNS.log("Warning! Link watchdog sleep time of 0!", RNS.LOG_ERROR)
if sleep_time == None or sleep_time < 0:
RNS.log("Timing error! Tearing down link "+str(self)+" now.", RNS.LOG_ERROR)
self.teardown()
sleep_time = 0.1
sleep(sleep_time)
def __update_phy_stats(self, packet):
if packet.rssi != None:
self.rssi = packet.rssi
if packet.snr != None:
self.snr = packet.snr
if packet.q != None:
self.q = packet.q
def send_keepalive(self):
keepalive_packet = RNS.Packet(self, bytes([0xFF]), context=RNS.Packet.KEEPALIVE)
keepalive_packet.send()
self.had_outbound()
def handle_request(self, request_id, unpacked_request):
if self.status == Link.ACTIVE:
requested_at = unpacked_request[0]
path_hash = unpacked_request[1]
request_data = unpacked_request[2]
if path_hash in self.destination.request_handlers:
request_handler = self.destination.request_handlers[path_hash]
path = request_handler[0]
response_generator = request_handler[1]
allow = request_handler[2]
allowed_list = request_handler[3]
allowed = False
if not allow == RNS.Destination.ALLOW_NONE:
if allow == RNS.Destination.ALLOW_LIST:
if self.__remote_identity != None and self.__remote_identity.hash in allowed_list:
allowed = True
elif allow == RNS.Destination.ALLOW_ALL:
allowed = True
if allowed:
RNS.log("Handling request "+RNS.prettyhexrep(request_id)+" for: "+str(path), RNS.LOG_DEBUG)
if len(inspect.signature(response_generator).parameters) == 5:
response = response_generator(path, request_data, request_id, self.__remote_identity, requested_at)
elif len(inspect.signature(response_generator).parameters) == 6:
response = response_generator(path, request_data, request_id, self.link_id, self.__remote_identity, requested_at)
else:
raise TypeError("Invalid signature for response generator callback")
if response != None:
packed_response = umsgpack.packb([request_id, response])
if len(packed_response) <= Link.MDU:
RNS.Packet(self, packed_response, RNS.Packet.DATA, context = RNS.Packet.RESPONSE).send()
else:
response_resource = RNS.Resource(packed_response, self, request_id = request_id, is_response = True)
else:
identity_string = str(self.get_remote_identity()) if self.get_remote_identity() != None else "<Unknown>"
RNS.log("Request "+RNS.prettyhexrep(request_id)+" from "+identity_string+" not allowed for: "+str(path), RNS.LOG_DEBUG)
def handle_response(self, request_id, response_data, response_size, response_transfer_size):
if self.status == Link.ACTIVE:
remove = None
for pending_request in self.pending_requests:
if pending_request.request_id == request_id:
remove = pending_request
try:
pending_request.response_size = response_size
pending_request.response_transfer_size = response_transfer_size
pending_request.response_received(response_data)
except Exception as e:
RNS.log("Error occurred while handling response. The contained exception was: "+str(e), RNS.LOG_ERROR)
break
if remove != None:
if remove in self.pending_requests:
self.pending_requests.remove(remove)
def request_resource_concluded(self, resource):
if resource.status == RNS.Resource.COMPLETE:
packed_request = resource.data.read()
unpacked_request = umsgpack.unpackb(packed_request)
request_id = RNS.Identity.truncated_hash(packed_request)
request_data = unpacked_request
self.handle_request(request_id, request_data)
else:
RNS.log("Incoming request resource failed with status: "+RNS.hexrep([resource.status]), RNS.LOG_DEBUG)
def response_resource_concluded(self, resource):
if resource.status == RNS.Resource.COMPLETE:
packed_response = resource.data.read()
unpacked_response = umsgpack.unpackb(packed_response)
request_id = unpacked_response[0]
response_data = unpacked_response[1]
self.handle_response(request_id, response_data, resource.total_size, resource.size)
else:
RNS.log("Incoming response resource failed with status: "+RNS.hexrep([resource.status]), RNS.LOG_DEBUG)
for pending_request in self.pending_requests:
if pending_request.request_id == resource.request_id:
pending_request.request_timed_out(None)
def get_channel(self):
"""
Get the ``Channel`` for this link.
:return: ``Channel`` object
"""
if self._channel is None:
self._channel = Channel(LinkChannelOutlet(self))
return self._channel
def receive(self, packet):
self.watchdog_lock = True
if not self.status == Link.CLOSED and not (self.initiator and packet.context == RNS.Packet.KEEPALIVE and packet.data == bytes([0xFF])):
if packet.receiving_interface != self.attached_interface:
RNS.log("Link-associated packet received on unexpected interface! Someone might be trying to manipulate your communication!", RNS.LOG_ERROR)
else:
self.last_inbound = time.time()
self.rx += 1
self.rxbytes += len(packet.data)
if self.status == Link.STALE:
self.status = Link.ACTIVE
if packet.packet_type == RNS.Packet.DATA:
if packet.context == RNS.Packet.NONE:
plaintext = self.decrypt(packet.data)
if self.callbacks.packet != None:
thread = threading.Thread(target=self.callbacks.packet, args=(plaintext, packet))
thread.daemon = True
thread.start()
if self.destination.proof_strategy == RNS.Destination.PROVE_ALL:
packet.prove()
elif self.destination.proof_strategy == RNS.Destination.PROVE_APP:
if self.destination.callbacks.proof_requested:
try:
self.destination.callbacks.proof_requested(packet)
except Exception as e:
RNS.log("Error while executing proof request callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
self.__update_phy_stats(packet)
elif packet.context == RNS.Packet.LINKIDENTIFY:
plaintext = self.decrypt(packet.data)
if not self.initiator and len(plaintext) == RNS.Identity.KEYSIZE//8 + RNS.Identity.SIGLENGTH//8:
public_key = plaintext[:RNS.Identity.KEYSIZE//8]
signed_data = self.link_id+public_key
signature = plaintext[RNS.Identity.KEYSIZE//8:RNS.Identity.KEYSIZE//8+RNS.Identity.SIGLENGTH//8]
identity = RNS.Identity(create_keys=False)
identity.load_public_key(public_key)
if identity.validate(signature, signed_data):
self.__remote_identity = identity
if self.callbacks.remote_identified != None:
try:
self.callbacks.remote_identified(self, self.__remote_identity)
except Exception as e:
RNS.log("Error while executing remote identified callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
self.__update_phy_stats(packet)
elif packet.context == RNS.Packet.REQUEST:
try:
request_id = packet.getTruncatedHash()
packed_request = self.decrypt(packet.data)
unpacked_request = umsgpack.unpackb(packed_request)
self.handle_request(request_id, unpacked_request)
self.__update_phy_stats(packet)
except Exception as e:
RNS.log("Error occurred while handling request. The contained exception was: "+str(e), RNS.LOG_ERROR)
elif packet.context == RNS.Packet.RESPONSE:
try:
packed_response = self.decrypt(packet.data)
unpacked_response = umsgpack.unpackb(packed_response)
request_id = unpacked_response[0]
response_data = unpacked_response[1]
transfer_size = len(umsgpack.packb(response_data))-2
self.handle_response(request_id, response_data, transfer_size, transfer_size)
self.__update_phy_stats(packet)
except Exception as e:
RNS.log("Error occurred while handling response. The contained exception was: "+str(e), RNS.LOG_ERROR)
elif packet.context == RNS.Packet.LRRTT:
if not self.initiator:
self.rtt_packet(packet)
self.__update_phy_stats(packet)
elif packet.context == RNS.Packet.LINKCLOSE:
self.teardown_packet(packet)
elif packet.context == RNS.Packet.RESOURCE_ADV:
packet.plaintext = self.decrypt(packet.data)
self.__update_phy_stats(packet)
if RNS.ResourceAdvertisement.is_request(packet):
RNS.Resource.accept(packet, callback=self.request_resource_concluded)
elif RNS.ResourceAdvertisement.is_response(packet):
request_id = RNS.ResourceAdvertisement.read_request_id(packet)
for pending_request in self.pending_requests:
if pending_request.request_id == request_id:
RNS.Resource.accept(packet, callback=self.response_resource_concluded, progress_callback=pending_request.response_resource_progress, request_id = request_id)
pending_request.response_size = RNS.ResourceAdvertisement.read_size(packet)
pending_request.response_transfer_size = RNS.ResourceAdvertisement.read_transfer_size(packet)
pending_request.started_at = time.time()
elif self.resource_strategy == Link.ACCEPT_NONE:
pass
elif self.resource_strategy == Link.ACCEPT_APP:
if self.callbacks.resource != None:
try:
resource_advertisement = RNS.ResourceAdvertisement.unpack(packet.plaintext)
resource_advertisement.link = self
if self.callbacks.resource(resource_advertisement):
RNS.Resource.accept(packet, self.callbacks.resource_concluded)
except Exception as e:
RNS.log("Error while executing resource accept callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
elif self.resource_strategy == Link.ACCEPT_ALL:
RNS.Resource.accept(packet, self.callbacks.resource_concluded)
elif packet.context == RNS.Packet.RESOURCE_REQ:
plaintext = self.decrypt(packet.data)
self.__update_phy_stats(packet)
if ord(plaintext[:1]) == RNS.Resource.HASHMAP_IS_EXHAUSTED:
resource_hash = plaintext[1+RNS.Resource.MAPHASH_LEN:RNS.Identity.HASHLENGTH//8+1+RNS.Resource.MAPHASH_LEN]
else:
resource_hash = plaintext[1:RNS.Identity.HASHLENGTH//8+1]
for resource in self.outgoing_resources:
if resource.hash == resource_hash:
# We need to check that this request has not been
# received before in order to avoid sequencing errors.
if not packet.packet_hash in resource.req_hashlist:
resource.req_hashlist.append(packet.packet_hash)
resource.request(plaintext)
elif packet.context == RNS.Packet.RESOURCE_HMU:
plaintext = self.decrypt(packet.data)
self.__update_phy_stats(packet)
resource_hash = plaintext[:RNS.Identity.HASHLENGTH//8]
for resource in self.incoming_resources:
if resource_hash == resource.hash:
resource.hashmap_update_packet(plaintext)
elif packet.context == RNS.Packet.RESOURCE_ICL:
plaintext = self.decrypt(packet.data)
self.__update_phy_stats(packet)
resource_hash = plaintext[:RNS.Identity.HASHLENGTH//8]
for resource in self.incoming_resources:
if resource_hash == resource.hash:
resource.cancel()
elif packet.context == RNS.Packet.KEEPALIVE:
if not self.initiator and packet.data == bytes([0xFF]):
keepalive_packet = RNS.Packet(self, bytes([0xFE]), context=RNS.Packet.KEEPALIVE)
keepalive_packet.send()
self.had_outbound()
# TODO: find the most efficient way to allow multiple
# transfers at the same time, sending resource hash on
# each packet is a huge overhead. Probably some kind
# of hash -> sequence map
elif packet.context == RNS.Packet.RESOURCE:
for resource in self.incoming_resources:
resource.receive_part(packet)
self.__update_phy_stats(packet)
elif packet.context == RNS.Packet.CHANNEL:
if not self._channel:
RNS.log(f"Channel data received without open channel", RNS.LOG_DEBUG)
else:
# TODO: Remove packet loss simulator ######
# if not hasattr(self, "drop_counter"):
# self.drop_counter = 0
# self.drop_counter += 1
# if self.drop_counter%6 == 0:
# RNS.log("Dropping channel packet for testing", RNS.LOG_DEBUG)
# else:
# packet.prove()
# plaintext = self.decrypt(packet.data)
# self._channel._receive(plaintext)
############################################
packet.prove()
plaintext = self.decrypt(packet.data)
self.__update_phy_stats(packet)
self._channel._receive(plaintext)
elif packet.packet_type == RNS.Packet.PROOF:
if packet.context == RNS.Packet.RESOURCE_PRF:
resource_hash = packet.data[0:RNS.Identity.HASHLENGTH//8]
for resource in self.outgoing_resources:
if resource_hash == resource.hash:
resource.validate_proof(packet.data)
self.__update_phy_stats(packet)
self.watchdog_lock = False
def encrypt(self, plaintext):
try:
if not self.fernet:
try:
self.fernet = Fernet(self.derived_key)
except Exception as e:
RNS.log("Could not instantiate Fernet while performin encryption on link "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
raise e
return self.fernet.encrypt(plaintext)
except Exception as e:
RNS.log("Encryption on link "+str(self)+" failed. The contained exception was: "+str(e), RNS.LOG_ERROR)
raise e
def decrypt(self, ciphertext):
try:
if not self.fernet:
self.fernet = Fernet(self.derived_key)
return self.fernet.decrypt(ciphertext)
except Exception as e:
RNS.log("Decryption failed on link "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
def sign(self, message):
return self.sig_prv.sign(message)
def validate(self, signature, message):
try:
self.peer_sig_pub.verify(signature, message)
return True
except Exception as e:
return False
def set_link_established_callback(self, callback):
self.callbacks.link_established = callback
def set_link_closed_callback(self, callback):
"""
Registers a function to be called when a link has been
torn down.
:param callback: A function or method with the signature *callback(link)* to be called.
"""
self.callbacks.link_closed = callback
def set_packet_callback(self, callback):
"""
Registers a function to be called when a packet has been
received over this link.
:param callback: A function or method with the signature *callback(message, packet)* to be called.
"""
self.callbacks.packet = callback
def set_resource_callback(self, callback):
"""
Registers a function to be called when a resource has been
advertised over this link. If the function returns *True*
the resource will be accepted. If it returns *False* it will
be ignored.
:param callback: A function or method with the signature *callback(resource)* to be called. Please note that only the basic information of the resource is available at this time, such as *get_transfer_size()*, *get_data_size()*, *get_parts()* and *is_compressed()*.
"""
self.callbacks.resource = callback
def set_resource_started_callback(self, callback):
"""
Registers a function to be called when a resource has begun
transferring over this link.
:param callback: A function or method with the signature *callback(resource)* to be called.
"""
self.callbacks.resource_started = callback
def set_resource_concluded_callback(self, callback):
"""
Registers a function to be called when a resource has concluded
transferring over this link.
:param callback: A function or method with the signature *callback(resource)* to be called.
"""
self.callbacks.resource_concluded = callback
def set_remote_identified_callback(self, callback):
"""
Registers a function to be called when an initiating peer has
identified over this link.
:param callback: A function or method with the signature *callback(link, identity)* to be called.
"""
self.callbacks.remote_identified = callback
def resource_concluded(self, resource):
if resource in self.incoming_resources:
self.incoming_resources.remove(resource)
if resource in self.outgoing_resources:
self.outgoing_resources.remove(resource)
def set_resource_strategy(self, resource_strategy):
"""
Sets the resource strategy for the link.
:param resource_strategy: One of ``RNS.Link.ACCEPT_NONE``, ``RNS.Link.ACCEPT_ALL`` or ``RNS.Link.ACCEPT_APP``. If ``RNS.Link.ACCEPT_APP`` is set, the `resource_callback` will be called to determine whether the resource should be accepted or not.
:raises: *TypeError* if the resource strategy is unsupported.
"""
if not resource_strategy in Link.resource_strategies:
raise TypeError("Unsupported resource strategy")
else:
self.resource_strategy = resource_strategy
def register_outgoing_resource(self, resource):
self.outgoing_resources.append(resource)
def register_incoming_resource(self, resource):
self.incoming_resources.append(resource)
def has_incoming_resource(self, resource):
for incoming_resource in self.incoming_resources:
if incoming_resource.hash == resource.hash:
return True
return False
def cancel_outgoing_resource(self, resource):
if resource in self.outgoing_resources:
self.outgoing_resources.remove(resource)
else:
RNS.log("Attempt to cancel a non-existing outgoing resource", RNS.LOG_ERROR)
def cancel_incoming_resource(self, resource):
if resource in self.incoming_resources:
self.incoming_resources.remove(resource)
else:
RNS.log("Attempt to cancel a non-existing incoming resource", RNS.LOG_ERROR)
def ready_for_new_resource(self):
if len(self.outgoing_resources) > 0:
return False
else:
return True
def __str__(self):
return RNS.prettyhexrep(self.link_id)
class RequestReceipt():
"""
An instance of this class is returned by the ``request`` method of ``RNS.Link``
instances. It should never be instantiated manually. It provides methods to
check status, response time and response data when the request concludes.
"""
FAILED = 0x00
SENT = 0x01
DELIVERED = 0x02
RECEIVING = 0x03
READY = 0x04
def __init__(self, link, packet_receipt = None, resource = None, response_callback = None, failed_callback = None, progress_callback = None, timeout = None, request_size = None):
self.packet_receipt = packet_receipt
self.resource = resource
self.started_at = None
if self.packet_receipt != None:
self.hash = packet_receipt.truncated_hash
self.packet_receipt.set_timeout_callback(self.request_timed_out)
self.started_at = time.time()
elif self.resource != None:
self.hash = resource.request_id
resource.set_callback(self.request_resource_concluded)
self.link = link
self.request_id = self.hash
self.request_size = request_size
self.response = None
self.response_transfer_size = None
self.response_size = None
self.status = RequestReceipt.SENT
self.sent_at = time.time()
self.progress = 0
self.concluded_at = None
self.response_concluded_at = None
if timeout != None:
self.timeout = timeout
else:
raise ValueError("No timeout specified for request receipt")
self.callbacks = RequestReceiptCallbacks()
self.callbacks.response = response_callback
self.callbacks.failed = failed_callback
self.callbacks.progress = progress_callback
self.link.pending_requests.append(self)
def request_resource_concluded(self, resource):
if resource.status == RNS.Resource.COMPLETE:
RNS.log("Request "+RNS.prettyhexrep(self.request_id)+" successfully sent as resource.", RNS.LOG_DEBUG)
self.started_at = time.time()
self.status = RequestReceipt.DELIVERED
self.__resource_response_timeout = time.time()+self.timeout
response_timeout_thread = threading.Thread(target=self.__response_timeout_job)
response_timeout_thread.daemon = True
response_timeout_thread.start()
else:
RNS.log("Sending request "+RNS.prettyhexrep(self.request_id)+" as resource failed with status: "+RNS.hexrep([resource.status]), RNS.LOG_DEBUG)
self.status = RequestReceipt.FAILED
self.concluded_at = time.time()
self.link.pending_requests.remove(self)
if self.callbacks.failed != None:
try:
self.callbacks.failed(self)
except Exception as e:
RNS.log("Error while executing request failed callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
def __response_timeout_job(self):
while self.status == RequestReceipt.DELIVERED:
now = time.time()
if now > self.__resource_response_timeout:
self.request_timed_out(None)
time.sleep(0.1)
def request_timed_out(self, packet_receipt):
self.status = RequestReceipt.FAILED
self.concluded_at = time.time()
self.link.pending_requests.remove(self)
if self.callbacks.failed != None:
try:
self.callbacks.failed(self)
except Exception as e:
RNS.log("Error while executing request timed out callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
def response_resource_progress(self, resource):
if not self.status == RequestReceipt.FAILED:
self.status = RequestReceipt.RECEIVING
if self.packet_receipt != None:
self.packet_receipt.status = RNS.PacketReceipt.DELIVERED
self.packet_receipt.proved = True
self.packet_receipt.concluded_at = time.time()
if self.packet_receipt.callbacks.delivery != None:
self.packet_receipt.callbacks.delivery(self.packet_receipt)
self.progress = resource.get_progress()
if self.callbacks.progress != None:
try:
self.callbacks.progress(self)
except Exception as e:
RNS.log("Error while executing response progress callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
else:
resource.cancel()
def response_received(self, response):
if not self.status == RequestReceipt.FAILED:
self.progress = 1.0
self.response = response
self.status = RequestReceipt.READY
self.response_concluded_at = time.time()
if self.packet_receipt != None:
self.packet_receipt.status = RNS.PacketReceipt.DELIVERED
self.packet_receipt.proved = True
self.packet_receipt.concluded_at = time.time()
if self.packet_receipt.callbacks.delivery != None:
self.packet_receipt.callbacks.delivery(self.packet_receipt)
if self.callbacks.progress != None:
try:
self.callbacks.progress(self)
except Exception as e:
RNS.log("Error while executing response progress callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
if self.callbacks.response != None:
try:
self.callbacks.response(self)
except Exception as e:
RNS.log("Error while executing response received callback from "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
def get_request_id(self):
"""
:returns: The request ID as *bytes*.
"""
return self.request_id
def get_status(self):
"""
:returns: The current status of the request, one of ``RNS.RequestReceipt.FAILED``, ``RNS.RequestReceipt.SENT``, ``RNS.RequestReceipt.DELIVERED``, ``RNS.RequestReceipt.READY``.
"""
return self.status
def get_progress(self):
"""
:returns: The progress of a response being received as a *float* between 0.0 and 1.0.
"""
return self.progress
def get_response(self):
"""
:returns: The response as *bytes* if it is ready, otherwise *None*.
"""
if self.status == RequestReceipt.READY:
return self.response
else:
return None
def get_response_time(self):
"""
:returns: The response time of the request in seconds.
"""
if self.status == RequestReceipt.READY:
return self.response_concluded_at - self.started_at
else:
return None
class RequestReceiptCallbacks:
def __init__(self):
self.response = None
self.failed = None
self.progress = None
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