517 lines
17 KiB
Python
517 lines
17 KiB
Python
from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives import serialization
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from cryptography.hazmat.primitives.asymmetric import ec
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from cryptography.hazmat.primitives.kdf.hkdf import HKDF
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from cryptography.fernet import Fernet
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from time import sleep
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import vendor.umsgpack as umsgpack
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import threading
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import base64
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import time
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import RNS
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import traceback
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class LinkCallbacks:
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def __init__(self):
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self.link_established = None
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self.link_closed = None
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self.packet = None
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self.resource_started = None
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self.resource_concluded = None
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class Link:
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CURVE = ec.SECP256R1()
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ECPUBSIZE = 91
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BLOCKSIZE = 16
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# TODO: This should not be hardcoded,
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# but calculated from something like
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# first-hop RTT latency and distance
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DEFAULT_TIMEOUT = 15.0
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TIMEOUT_FACTOR = 3
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KEEPALIVE = 120
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PENDING = 0x00
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HANDSHAKE = 0x01
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ACTIVE = 0x02
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STALE = 0x03
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CLOSED = 0x04
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TIMEOUT = 0x01
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INITIATOR_CLOSED = 0x02
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DESTINATION_CLOSED = 0x03
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ACCEPT_NONE = 0x00
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ACCEPT_APP = 0x01
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ACCEPT_ALL = 0x02
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resource_strategies = [ACCEPT_NONE, ACCEPT_APP, ACCEPT_ALL]
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@staticmethod
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def validateRequest(owner, data, packet):
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if len(data) == (Link.ECPUBSIZE):
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try:
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link = Link(owner = owner, peer_pub_bytes = data[:Link.ECPUBSIZE])
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link.setLinkID(packet)
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link.destination = packet.destination
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RNS.log("Validating link request "+RNS.prettyhexrep(link.link_id), RNS.LOG_VERBOSE)
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link.handshake()
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link.attached_interface = packet.receiving_interface
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link.prove()
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link.request_time = time.time()
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RNS.Transport.registerLink(link)
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link.last_inbound = time.time()
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link.start_watchdog()
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if link.owner.callbacks.link_established != None:
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link.owner.callbacks.link_established(link)
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RNS.log("Incoming link request "+str(link)+" accepted", RNS.LOG_VERBOSE)
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return link
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except Exception as e:
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RNS.log("Validating link request failed", RNS.LOG_VERBOSE)
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traceback.print_exc()
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return None
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else:
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RNS.log("Invalid link request payload size, dropping request", RNS.LOG_VERBOSE)
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return None
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def __init__(self, destination=None, owner=None, peer_pub_bytes = None):
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if destination != None and destination.type != RNS.Destination.SINGLE:
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raise TypeError("Links can only be established to the \"single\" destination type")
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self.rtt = None
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self.callbacks = LinkCallbacks()
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self.resource_strategy = Link.ACCEPT_NONE
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self.outgoing_resources = []
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self.incoming_resources = []
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self.last_inbound = 0
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self.last_outbound = 0
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self.tx = 0
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self.rx = 0
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self.txbytes = 0
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self.rxbytes = 0
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self.default_timeout = Link.DEFAULT_TIMEOUT
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self.proof_timeout = self.default_timeout
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self.timeout_factor = Link.TIMEOUT_FACTOR
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self.keepalive = Link.KEEPALIVE
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self.watchdog_lock = False
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self.status = Link.PENDING
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self.type = RNS.Destination.LINK
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self.owner = owner
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self.destination = destination
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self.attached_interface = None
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self.__encryption_disabled = False
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if self.destination == None:
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self.initiator = False
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else:
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self.initiator = True
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self.prv = ec.generate_private_key(Link.CURVE, default_backend())
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self.pub = self.prv.public_key()
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self.pub_bytes = self.pub.public_bytes(
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encoding=serialization.Encoding.DER,
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format=serialization.PublicFormat.SubjectPublicKeyInfo
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)
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if peer_pub_bytes == None:
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self.peer_pub = None
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self.peer_pub_bytes = None
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else:
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self.loadPeer(peer_pub_bytes)
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if (self.initiator):
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self.request_data = self.pub_bytes
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self.packet = RNS.Packet(destination, self.request_data, packet_type=RNS.Packet.LINKREQUEST)
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self.packet.pack()
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self.setLinkID(self.packet)
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RNS.Transport.registerLink(self)
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self.request_time = time.time()
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self.start_watchdog()
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self.packet.send()
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RNS.log("Link request "+RNS.prettyhexrep(self.link_id)+" sent to "+str(self.destination), RNS.LOG_VERBOSE)
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def loadPeer(self, peer_pub_bytes):
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self.peer_pub_bytes = peer_pub_bytes
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self.peer_pub = serialization.load_der_public_key(peer_pub_bytes, backend=default_backend())
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if not hasattr(self.peer_pub, "curve"):
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self.peer_pub.curve = Link.CURVE
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def setLinkID(self, packet):
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self.link_id = RNS.Identity.truncatedHash(packet.raw)
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self.hash = self.link_id
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def handshake(self):
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self.status = Link.HANDSHAKE
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self.shared_key = self.prv.exchange(ec.ECDH(), self.peer_pub)
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self.derived_key = HKDF(
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algorithm=hashes.SHA256(),
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length=32,
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salt=self.getSalt(),
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info=self.getContext(),
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backend=default_backend()
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).derive(self.shared_key)
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def prove(self):
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signed_data = self.link_id+self.pub_bytes
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signature = self.owner.identity.sign(signed_data)
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proof_data = self.pub_bytes+signature
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proof = RNS.Packet(self, proof_data, packet_type=RNS.Packet.PROOF, context=RNS.Packet.LRPROOF)
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proof.send()
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def prove_packet(self, packet):
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signature = self.sign(packet.packet_hash)
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# TODO: Hardcoded as explicit proof for now
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# if RNS.Reticulum.should_use_implicit_proof():
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# proof_data = signature
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# else:
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# proof_data = packet.packet_hash + signature
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proof_data = packet.packet_hash + signature
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proof = RNS.Packet(self, proof_data, RNS.Packet.PROOF)
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proof.send()
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def validateProof(self, packet):
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if self.initiator:
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peer_pub_bytes = packet.data[:Link.ECPUBSIZE]
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signed_data = self.link_id+peer_pub_bytes
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signature = packet.data[Link.ECPUBSIZE:RNS.Identity.KEYSIZE/8+Link.ECPUBSIZE]
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if self.destination.identity.validate(signature, signed_data):
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self.loadPeer(peer_pub_bytes)
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self.handshake()
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self.rtt = time.time() - self.request_time
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self.attached_interface = packet.receiving_interface
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RNS.Transport.activateLink(self)
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RNS.log("Link "+str(self)+" established with "+str(self.destination)+", RTT is "+str(self.rtt), RNS.LOG_VERBOSE)
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rtt_data = umsgpack.packb(self.rtt)
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rtt_packet = RNS.Packet(self, rtt_data, context=RNS.Packet.LRRTT)
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# TODO: remove
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RNS.log("Sending RTT packet", RNS.LOG_EXTREME)
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rtt_packet.send()
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self.status = Link.ACTIVE
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if self.callbacks.link_established != None:
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self.callbacks.link_established(self)
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else:
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RNS.log("Invalid link proof signature received by "+str(self), RNS.LOG_VERBOSE)
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# TODO: should we really do this, or just wait
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# for a valid one? Needs analysis.
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self.teardown()
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def rtt_packet(self, packet):
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try:
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# TODO: This is crude, we should use the delta
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# to model a more representative per-bit round
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# trip time, and use that to set a sensible RTT
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# expectancy for the link. This will have to do
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# for now though.
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measured_rtt = time.time() - self.request_time
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plaintext = self.decrypt(packet.data)
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rtt = umsgpack.unpackb(plaintext)
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self.rtt = max(measured_rtt, rtt)
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self.status = Link.ACTIVE
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except Exception as e:
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self.teardown()
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def getSalt(self):
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return self.link_id
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def getContext(self):
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return None
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def teardown(self):
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if self.status != Link.PENDING and self.status != Link.CLOSED:
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teardown_packet = RNS.Packet(self, self.link_id, context=RNS.Packet.LINKCLOSE)
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teardown_packet.send()
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self.status = Link.CLOSED
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if self.initiator:
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self.teardown_reason = Link.INITIATOR_CLOSED
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else:
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self.teardown_reason = Link.DESTINATION_CLOSED
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self.link_closed()
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def teardown_packet(self, packet):
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try:
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plaintext = self.decrypt(packet.data)
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if plaintext == self.link_id:
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self.status = Link.CLOSED
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if self.initiator:
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self.teardown_reason = Link.DESTINATION_CLOSED
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else:
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self.teardown_reason = Link.INITIATOR_CLOSED
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self.link_closed()
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except Exception as e:
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pass
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def link_closed(self):
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for resource in self.incoming_resources:
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resource.cancel()
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for resource in self.outgoing_resources:
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resource.cancel()
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self.prv = None
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self.pub = None
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self.pub_bytes = None
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self.shared_key = None
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self.derived_key = None
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if self.callbacks.link_closed != None:
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self.callbacks.link_closed(self)
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def start_watchdog(self):
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thread = threading.Thread(target=self.__watchdog_job)
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thread.setDaemon(True)
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thread.start()
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def __watchdog_job(self):
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while not self.status == Link.CLOSED:
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while (self.watchdog_lock):
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sleep(max(self.rtt, 0.025))
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if not self.status == Link.CLOSED:
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# Link was initiated, but no response
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# from destination yet
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if self.status == Link.PENDING:
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next_check = self.request_time + self.proof_timeout
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sleep_time = next_check - time.time()
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if time.time() >= self.request_time + self.proof_timeout:
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RNS.log("Link establishment timed out", RNS.LOG_VERBOSE)
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self.status = Link.CLOSED
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self.teardown_reason = Link.TIMEOUT
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self.link_closed()
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sleep_time = 0.001
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elif self.status == Link.HANDSHAKE:
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next_check = self.request_time + self.proof_timeout
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sleep_time = next_check - time.time()
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if time.time() >= self.request_time + self.proof_timeout:
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RNS.log("Timeout waiting for RTT packet from link initiator", RNS.LOG_DEBUG)
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self.status = Link.CLOSED
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self.teardown_reason = Link.TIMEOUT
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self.link_closed()
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sleep_time = 0.001
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elif self.status == Link.ACTIVE:
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if time.time() >= self.last_inbound + self.keepalive:
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sleep_time = self.rtt * self.timeout_factor
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self.status = Link.STALE
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if self.initiator:
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self.send_keepalive()
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else:
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sleep_time = (self.last_inbound + self.keepalive) - time.time()
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elif self.status == Link.STALE:
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sleep_time = 0.001
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self.status = Link.CLOSED
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self.teardown_reason = Link.TIMEOUT
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self.link_closed()
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if sleep_time == 0:
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RNS.log("Warning! Link watchdog sleep time of 0!", RNS.LOG_ERROR)
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if sleep_time == None or sleep_time < 0:
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RNS.log("Timing error! Closing Reticulum now.", RNS.LOG_CRITICAL)
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RNS.panic()
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sleep(sleep_time)
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def send_keepalive(self):
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keepalive_packet = RNS.Packet(self, chr(0xFF), context=RNS.Packet.KEEPALIVE)
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keepalive_packet.send()
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def receive(self, packet):
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self.watchdog_lock = True
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if not self.status == Link.CLOSED and not (self.initiator and packet.context == RNS.Packet.KEEPALIVE and packet.data == chr(0xFF)):
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if packet.receiving_interface != self.attached_interface:
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RNS.log("Link-associated packet received on unexpected interface! Someone might be trying to manipulate your communication!", RNS.LOG_ERROR)
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else:
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self.last_inbound = time.time()
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self.rx += 1
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self.rxbytes += len(packet.data)
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if self.status == Link.STALE:
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self.status = Link.ACTIVE
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if packet.packet_type == RNS.Packet.DATA:
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if packet.context == RNS.Packet.NONE:
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plaintext = self.decrypt(packet.data)
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if self.callbacks.packet != None:
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self.callbacks.packet(plaintext, packet)
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if self.destination.proof_strategy == RNS.Destination.PROVE_ALL:
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packet.prove()
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elif self.destination.proof_strategy == RNS.Destination.PROVE_APP:
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if self.destination.callbacks.proof_requested:
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self.destination.callbacks.proof_requested(packet)
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elif packet.context == RNS.Packet.LRRTT:
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if not self.initiator:
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self.rtt_packet(packet)
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elif packet.context == RNS.Packet.LINKCLOSE:
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self.teardown_packet(packet)
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elif packet.context == RNS.Packet.RESOURCE_ADV:
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packet.plaintext = self.decrypt(packet.data)
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if self.resource_strategy == Link.ACCEPT_NONE:
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pass
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elif self.resource_strategy == Link.ACCEPT_APP:
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if self.callbacks.resource != None:
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self.callbacks.resource(packet)
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elif self.resource_strategy == Link.ACCEPT_ALL:
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RNS.Resource.accept(packet, self.callbacks.resource_concluded)
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elif packet.context == RNS.Packet.RESOURCE_REQ:
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plaintext = self.decrypt(packet.data)
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if ord(plaintext[:1]) == RNS.Resource.HASHMAP_IS_EXHAUSTED:
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resource_hash = plaintext[1+RNS.Resource.MAPHASH_LEN:RNS.Identity.HASHLENGTH/8+1+RNS.Resource.MAPHASH_LEN]
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else:
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resource_hash = plaintext[1:RNS.Identity.HASHLENGTH/8+1]
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for resource in self.outgoing_resources:
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if resource.hash == resource_hash:
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resource.request(plaintext)
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elif packet.context == RNS.Packet.RESOURCE_HMU:
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plaintext = self.decrypt(packet.data)
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resource_hash = plaintext[:RNS.Identity.HASHLENGTH/8]
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for resource in self.incoming_resources:
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if resource_hash == resource.hash:
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resource.hashmap_update_packet(plaintext)
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elif packet.context == RNS.Packet.RESOURCE_ICL:
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plaintext = self.decrypt(packet.data)
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resource_hash = plaintext[:RNS.Identity.HASHLENGTH/8]
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for resource in self.incoming_resources:
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if resource_hash == resource.hash:
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resource.cancel()
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elif packet.context == RNS.Packet.KEEPALIVE:
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if not self.initiator and packet.data == chr(0xFF):
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keepalive_packet = RNS.Packet(self, chr(0xFE), context=RNS.Packet.KEEPALIVE)
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keepalive_packet.send()
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# TODO: find the most efficient way to allow multiple
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# transfers at the same time, sending resource hash on
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# each packet is a huge overhead. Probably some kind
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# of hash -> sequence map
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elif packet.context == RNS.Packet.RESOURCE:
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for resource in self.incoming_resources:
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resource.receive_part(packet)
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elif packet.packet_type == RNS.Packet.PROOF:
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if packet.context == RNS.Packet.RESOURCE_PRF:
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resource_hash = packet.data[0:RNS.Identity.HASHLENGTH/8]
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for resource in self.outgoing_resources:
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if resource_hash == resource.hash:
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resource.validateProof(packet.data)
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self.watchdog_lock = False
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def encrypt(self, plaintext):
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if self.__encryption_disabled:
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return plaintext
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try:
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fernet = Fernet(base64.urlsafe_b64encode(self.derived_key))
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ciphertext = base64.urlsafe_b64decode(fernet.encrypt(plaintext))
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return ciphertext
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except Exception as e:
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RNS.log("Encryption on link "+str(self)+" failed. The contained exception was: "+str(e), RNS.LOG_ERROR)
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def decrypt(self, ciphertext):
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if self.__encryption_disabled:
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return ciphertext
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try:
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fernet = Fernet(base64.urlsafe_b64encode(self.derived_key))
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plaintext = fernet.decrypt(base64.urlsafe_b64encode(ciphertext))
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return plaintext
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except Exception as e:
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RNS.log("Decryption failed on link "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
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def sign(self, message):
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return self.prv.sign(message, ec.ECDSA(hashes.SHA256()))
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def validate(self, signature, message):
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try:
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self.peer_pub.verify(signature, message, ec.ECDSA(hashes.SHA256()))
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return True
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except Exception as e:
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return False
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def link_established_callback(self, callback):
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self.callbacks.link_established = callback
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def link_closed_callback(self, callback):
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self.callbacks.link_closed = callback
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def packet_callback(self, callback):
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self.callbacks.packet = callback
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# Called when an incoming resource transfer is started
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def resource_started_callback(self, callback):
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self.callbacks.resource_started = callback
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# Called when a resource transfer is concluded
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def resource_concluded_callback(self, callback):
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self.callbacks.resource_concluded = callback
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def resource_concluded(self, resource):
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if resource in self.incoming_resources:
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self.incoming_resources.remove(resource)
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if resource in self.outgoing_resources:
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self.outgoing_resources.remove(resource)
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def set_resource_strategy(self, resource_strategy):
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if not resource_strategy in Link.resource_strategies:
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raise TypeError("Unsupported resource strategy")
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else:
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self.resource_strategy = resource_strategy
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def register_outgoing_resource(self, resource):
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self.outgoing_resources.append(resource)
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def register_incoming_resource(self, resource):
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self.incoming_resources.append(resource)
|
|
|
|
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 incoming 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 disableEncryption(self):
|
|
if (RNS.Reticulum.should_allow_unencrypted()):
|
|
RNS.log("The link "+str(self)+" was downgraded to an encryptionless link", RNS.LOG_NOTICE)
|
|
self.__encryption_disabled = True
|
|
else:
|
|
RNS.log("Attempt to disable encryption on link, but encryptionless links are not allowed by config.", RNS.LOG_CRITICAL)
|
|
RNS.log("Shutting down Reticulum now!", RNS.LOG_CRITICAL)
|
|
RNS.panic()
|
|
|
|
def encryption_disabled(self):
|
|
return self.__encryption_disabled
|
|
|
|
def __str__(self):
|
|
return RNS.prettyhexrep(self.link_id) |