558 lines
22 KiB
Python
558 lines
22 KiB
Python
from cryptography.hazmat.backends import default_backend
|
|
from cryptography.hazmat.primitives import hashes
|
|
from cryptography.hazmat.primitives import serialization
|
|
from cryptography.hazmat.primitives.asymmetric import ec
|
|
from cryptography.hazmat.primitives.kdf.hkdf import HKDF
|
|
from cryptography.fernet import Fernet
|
|
from time import sleep
|
|
from .vendor import umsgpack as umsgpack
|
|
import threading
|
|
import base64
|
|
import math
|
|
import time
|
|
import RNS
|
|
|
|
import traceback
|
|
|
|
class LinkCallbacks:
|
|
def __init__(self):
|
|
self.link_established = None
|
|
self.link_closed = None
|
|
self.packet = None
|
|
self.resource_started = None
|
|
self.resource_concluded = None
|
|
|
|
class Link:
|
|
CURVE = ec.SECP256R1()
|
|
ECPUBSIZE = 91
|
|
BLOCKSIZE = 16
|
|
AES_HMAC_OVERHEAD = 58
|
|
MDU = math.floor((RNS.Reticulum.MDU-AES_HMAC_OVERHEAD)/BLOCKSIZE)*BLOCKSIZE - 1
|
|
|
|
# TODO: This should not be hardcoded,
|
|
# but calculated from something like
|
|
# first-hop RTT latency and distance
|
|
DEFAULT_TIMEOUT = 15.0
|
|
TIMEOUT_FACTOR = 3
|
|
STALE_GRACE = 2
|
|
KEEPALIVE = 180
|
|
|
|
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 validateRequest(owner, data, packet):
|
|
if len(data) == (Link.ECPUBSIZE):
|
|
try:
|
|
link = Link(owner = owner, peer_pub_bytes = data[:Link.ECPUBSIZE])
|
|
link.setLinkID(packet)
|
|
link.destination = packet.destination
|
|
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.registerLink(link)
|
|
link.last_inbound = time.time()
|
|
link.start_watchdog()
|
|
|
|
# TODO: Why was link_established callback here? Seems weird
|
|
# to call this before RTT packet has been received
|
|
#if self.owner.callbacks.link_established != None:
|
|
# self.owner.callbacks.link_established(link)
|
|
|
|
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)
|
|
traceback.print_exc()
|
|
return None
|
|
|
|
else:
|
|
RNS.log("Invalid link request payload size, dropping request", RNS.LOG_VERBOSE)
|
|
return None
|
|
|
|
|
|
def __init__(self, destination=None, owner=None, peer_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.callbacks = LinkCallbacks()
|
|
self.resource_strategy = Link.ACCEPT_NONE
|
|
self.outgoing_resources = []
|
|
self.incoming_resources = []
|
|
self.last_inbound = 0
|
|
self.last_outbound = 0
|
|
self.tx = 0
|
|
self.rx = 0
|
|
self.txbytes = 0
|
|
self.rxbytes = 0
|
|
self.default_timeout = Link.DEFAULT_TIMEOUT
|
|
self.proof_timeout = self.default_timeout
|
|
self.timeout_factor = Link.TIMEOUT_FACTOR
|
|
self.keepalive = Link.KEEPALIVE
|
|
self.watchdog_lock = False
|
|
self.status = Link.PENDING
|
|
self.type = RNS.Destination.LINK
|
|
self.owner = owner
|
|
self.destination = destination
|
|
self.attached_interface = None
|
|
self.__encryption_disabled = False
|
|
if self.destination == None:
|
|
self.initiator = False
|
|
else:
|
|
self.initiator = True
|
|
|
|
self.prv = ec.generate_private_key(Link.CURVE, default_backend())
|
|
self.pub = self.prv.public_key()
|
|
self.pub_bytes = self.pub.public_bytes(
|
|
encoding=serialization.Encoding.DER,
|
|
format=serialization.PublicFormat.SubjectPublicKeyInfo
|
|
)
|
|
|
|
if peer_pub_bytes == None:
|
|
self.peer_pub = None
|
|
self.peer_pub_bytes = None
|
|
else:
|
|
self.loadPeer(peer_pub_bytes)
|
|
|
|
if (self.initiator):
|
|
self.request_data = self.pub_bytes
|
|
self.packet = RNS.Packet(destination, self.request_data, packet_type=RNS.Packet.LINKREQUEST)
|
|
self.packet.pack()
|
|
self.setLinkID(self.packet)
|
|
RNS.Transport.registerLink(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_VERBOSE)
|
|
|
|
|
|
def loadPeer(self, peer_pub_bytes):
|
|
self.peer_pub_bytes = peer_pub_bytes
|
|
self.peer_pub = serialization.load_der_public_key(peer_pub_bytes, backend=default_backend())
|
|
if not hasattr(self.peer_pub, "curve"):
|
|
self.peer_pub.curve = Link.CURVE
|
|
|
|
def setLinkID(self, packet):
|
|
self.link_id = packet.getTruncatedHash()
|
|
self.hash = self.link_id
|
|
|
|
def handshake(self):
|
|
self.status = Link.HANDSHAKE
|
|
self.shared_key = self.prv.exchange(ec.ECDH(), self.peer_pub)
|
|
self.derived_key = HKDF(
|
|
algorithm=hashes.SHA256(),
|
|
length=32,
|
|
salt=self.getSalt(),
|
|
info=self.getContext(),
|
|
backend=default_backend()
|
|
).derive(self.shared_key)
|
|
|
|
def prove(self):
|
|
signed_data = self.link_id+self.pub_bytes
|
|
signature = self.owner.identity.sign(signed_data)
|
|
|
|
proof_data = self.pub_bytes+signature
|
|
proof = RNS.Packet(self, proof_data, packet_type=RNS.Packet.PROOF, context=RNS.Packet.LRPROOF)
|
|
proof.send()
|
|
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 validateProof(self, packet):
|
|
if self.initiator:
|
|
peer_pub_bytes = packet.data[:Link.ECPUBSIZE]
|
|
signed_data = self.link_id+peer_pub_bytes
|
|
signature = packet.data[Link.ECPUBSIZE:RNS.Identity.KEYSIZE//8+Link.ECPUBSIZE]
|
|
|
|
if self.destination.identity.validate(signature, signed_data):
|
|
self.loadPeer(peer_pub_bytes)
|
|
self.handshake()
|
|
self.rtt = time.time() - self.request_time
|
|
self.attached_interface = packet.receiving_interface
|
|
RNS.Transport.activateLink(self)
|
|
RNS.log("Link "+str(self)+" established with "+str(self.destination)+", RTT is "+str(self.rtt), RNS.LOG_VERBOSE)
|
|
rtt_data = umsgpack.packb(self.rtt)
|
|
rtt_packet = RNS.Packet(self, rtt_data, context=RNS.Packet.LRRTT)
|
|
RNS.log("Sending RTT packet", RNS.LOG_EXTREME);
|
|
rtt_packet.send()
|
|
self.had_outbound()
|
|
|
|
self.status = Link.ACTIVE
|
|
if self.callbacks.link_established != None:
|
|
thread = threading.Thread(target=self.callbacks.link_established, args=(self,))
|
|
thread.setDaemon(True)
|
|
thread.start()
|
|
else:
|
|
RNS.log("Invalid link proof signature received by "+str(self), RNS.LOG_VERBOSE)
|
|
# TODO: should we really do this, or just wait
|
|
# for a valid one? Needs analysis.
|
|
self.teardown()
|
|
|
|
|
|
def rtt_packet(self, packet):
|
|
try:
|
|
# TODO: This is crude, we should use the delta
|
|
# to model a more representative per-bit round
|
|
# trip time, and use that to set a sensible RTT
|
|
# expectancy for the link. This will have to do
|
|
# for now though.
|
|
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
|
|
|
|
if self.owner.callbacks.link_established != None:
|
|
self.owner.callbacks.link_established(self)
|
|
except Exception as e:
|
|
RNS.log("Error occurred while processing RTT packet, tearing down link", RNS.LOG_ERROR)
|
|
traceback.print_exc()
|
|
self.teardown()
|
|
|
|
def getSalt(self):
|
|
return self.link_id
|
|
|
|
def getContext(self):
|
|
return None
|
|
|
|
def no_inbound_for(self):
|
|
return time.time() - self.last_inbound
|
|
|
|
def no_outbound_for(self):
|
|
return time.time() - self.last_outbound
|
|
|
|
def inactive_for(self):
|
|
return min(self.no_inbound_for(), self.no_outbound_for())
|
|
|
|
def had_outbound(self):
|
|
self.last_outbound = time.time()
|
|
|
|
def teardown(self):
|
|
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.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()
|
|
|
|
self.prv = None
|
|
self.pub = None
|
|
self.pub_bytes = None
|
|
self.shared_key = None
|
|
self.derived_key = None
|
|
|
|
if self.callbacks.link_closed != None:
|
|
self.callbacks.link_closed(self)
|
|
|
|
def start_watchdog(self):
|
|
thread = threading.Thread(target=self.__watchdog_job)
|
|
thread.setDaemon(True)
|
|
thread.start()
|
|
|
|
def __watchdog_job(self):
|
|
while not self.status == Link.CLOSED:
|
|
while (self.watchdog_lock):
|
|
sleep(max(self.rtt, 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.proof_timeout
|
|
sleep_time = next_check - time.time()
|
|
if time.time() >= self.request_time + self.proof_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.proof_timeout
|
|
sleep_time = next_check - time.time()
|
|
if time.time() >= self.request_time + self.proof_timeout:
|
|
RNS.log("Timeout waiting for RTT packet from link initiator", RNS.LOG_DEBUG)
|
|
self.status = Link.CLOSED
|
|
self.teardown_reason = Link.TIMEOUT
|
|
self.link_closed()
|
|
sleep_time = 0.001
|
|
|
|
elif self.status == Link.ACTIVE:
|
|
if time.time() >= self.last_inbound + self.keepalive:
|
|
sleep_time = self.rtt * self.timeout_factor + Link.STALE_GRACE
|
|
self.status = Link.STALE
|
|
if self.initiator:
|
|
self.send_keepalive()
|
|
else:
|
|
sleep_time = (self.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 send_keepalive(self):
|
|
keepalive_packet = RNS.Packet(self, bytes([0xFF]), context=RNS.Packet.KEEPALIVE)
|
|
keepalive_packet.send()
|
|
self.had_outbound()
|
|
|
|
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.setDaemon(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:
|
|
self.destination.callbacks.proof_requested(packet)
|
|
|
|
elif packet.context == RNS.Packet.LRRTT:
|
|
if not self.initiator:
|
|
self.rtt_packet(packet)
|
|
|
|
elif packet.context == RNS.Packet.LINKCLOSE:
|
|
self.teardown_packet(packet)
|
|
|
|
elif packet.context == RNS.Packet.RESOURCE_ADV:
|
|
packet.plaintext = self.decrypt(packet.data)
|
|
if self.resource_strategy == Link.ACCEPT_NONE:
|
|
pass
|
|
elif self.resource_strategy == Link.ACCEPT_APP:
|
|
if self.callbacks.resource != None:
|
|
thread = threading.Thread(target=self.callbacks.resource, args=(packet))
|
|
thread.setDaemon(True)
|
|
thread.start()
|
|
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)
|
|
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:
|
|
resource.request(plaintext)
|
|
|
|
elif packet.context == RNS.Packet.RESOURCE_HMU:
|
|
plaintext = self.decrypt(packet.data)
|
|
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)
|
|
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)
|
|
|
|
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.validateProof(packet.data)
|
|
|
|
self.watchdog_lock = False
|
|
|
|
|
|
def encrypt(self, plaintext):
|
|
if self.__encryption_disabled:
|
|
return plaintext
|
|
try:
|
|
# TODO: Optimise this re-allocation
|
|
fernet = Fernet(base64.urlsafe_b64encode(self.derived_key))
|
|
ciphertext = base64.urlsafe_b64decode(fernet.encrypt(plaintext))
|
|
return ciphertext
|
|
except Exception as e:
|
|
RNS.log("Encryption on link "+str(self)+" failed. The contained exception was: "+str(e), RNS.LOG_ERROR)
|
|
|
|
|
|
def decrypt(self, ciphertext):
|
|
if self.__encryption_disabled:
|
|
return ciphertext
|
|
try:
|
|
fernet = Fernet(base64.urlsafe_b64encode(self.derived_key))
|
|
plaintext = fernet.decrypt(base64.urlsafe_b64encode(ciphertext))
|
|
return plaintext
|
|
except Exception as e:
|
|
RNS.log("Decryption failed on link "+str(self)+". The contained exception was: "+str(e), RNS.LOG_ERROR)
|
|
RNS.log(traceback.format_exc(), RNS.LOG_ERROR)
|
|
# TODO: Do we really need to do this? Or can we recover somehow?
|
|
self.teardown()
|
|
|
|
|
|
def sign(self, message):
|
|
return self.prv.sign(message, ec.ECDSA(hashes.SHA256()))
|
|
|
|
def validate(self, signature, message):
|
|
try:
|
|
self.peer_pub.verify(signature, message, ec.ECDSA(hashes.SHA256()))
|
|
return True
|
|
except Exception as e:
|
|
return False
|
|
|
|
def link_established_callback(self, callback):
|
|
self.callbacks.link_established = callback
|
|
|
|
def link_closed_callback(self, callback):
|
|
self.callbacks.link_closed = callback
|
|
|
|
def packet_callback(self, callback):
|
|
self.callbacks.packet = callback
|
|
|
|
# Called when an incoming resource transfer is started
|
|
def resource_started_callback(self, callback):
|
|
self.callbacks.resource_started = callback
|
|
|
|
# Called when a resource transfer is concluded
|
|
def resource_concluded_callback(self, callback):
|
|
self.callbacks.resource_concluded = 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):
|
|
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 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 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) |