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reticulum/RNS/Packet.py

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Python
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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.
import threading
import struct
import math
import time
import RNS
class Packet:
"""
The Packet class is used to create packet instances that can be sent
over a Reticulum network. Packets will automatically be encrypted if
they are addressed to a ``RNS.Destination.SINGLE`` destination,
``RNS.Destination.GROUP`` destination or a :ref:`RNS.Link<api-link>`.
For ``RNS.Destination.GROUP`` destinations, Reticulum will use the
pre-shared key configured for the destination. All packets to group
destinations are encrypted with the same AES-128 key.
For ``RNS.Destination.SINGLE`` destinations, Reticulum will use a newly
derived ephemeral AES-128 key for every packet.
For :ref:`RNS.Link<api-link>` destinations, Reticulum will use per-link
ephemeral keys, and offers **Forward Secrecy**.
:param destination: A :ref:`RNS.Destination<api-destination>` instance to which the packet will be sent.
:param data: The data payload to be included in the packet as *bytes*.
:param create_receipt: Specifies whether a :ref:`RNS.PacketReceipt<api-packetreceipt>` should be created when instantiating the packet.
"""
# Packet types
DATA = 0x00 # Data packets
ANNOUNCE = 0x01 # Announces
LINKREQUEST = 0x02 # Link requests
PROOF = 0x03 # Proofs
types = [DATA, ANNOUNCE, LINKREQUEST, PROOF]
# Header types
HEADER_1 = 0x00 # Normal header format
HEADER_2 = 0x01 # Header format used for packets in transport
header_types = [HEADER_1, HEADER_2]
# Packet context types
NONE = 0x00 # Generic data packet
RESOURCE = 0x01 # Packet is part of a resource
RESOURCE_ADV = 0x02 # Packet is a resource advertisement
RESOURCE_REQ = 0x03 # Packet is a resource part request
RESOURCE_HMU = 0x04 # Packet is a resource hashmap update
RESOURCE_PRF = 0x05 # Packet is a resource proof
RESOURCE_ICL = 0x06 # Packet is a resource initiator cancel message
RESOURCE_RCL = 0x07 # Packet is a resource receiver cancel message
CACHE_REQUEST = 0x08 # Packet is a cache request
REQUEST = 0x09 # Packet is a request
RESPONSE = 0x0A # Packet is a response to a request
PATH_RESPONSE = 0x0B # Packet is a response to a path request
COMMAND = 0x0C # Packet is a command
COMMAND_STATUS = 0x0D # Packet is a status of an executed command
CHANNEL = 0x0E # Packet contains link channel data
KEEPALIVE = 0xFA # Packet is a keepalive packet
LINKIDENTIFY = 0xFB # Packet is a link peer identification proof
LINKCLOSE = 0xFC # Packet is a link close message
LINKPROOF = 0xFD # Packet is a link packet proof
LRRTT = 0xFE # Packet is a link request round-trip time measurement
LRPROOF = 0xFF # Packet is a link request proof
# This is used to calculate allowable
# payload sizes
HEADER_MAXSIZE = RNS.Reticulum.HEADER_MAXSIZE
MDU = RNS.Reticulum.MDU
# With an MTU of 500, the maximum of data we can
# send in a single encrypted packet is given by
# the below calculation; 383 bytes.
ENCRYPTED_MDU = math.floor((RNS.Reticulum.MDU-RNS.Identity.FERNET_OVERHEAD-RNS.Identity.KEYSIZE//16)/RNS.Identity.AES128_BLOCKSIZE)*RNS.Identity.AES128_BLOCKSIZE - 1
"""
The maximum size of the payload data in a single encrypted packet
"""
PLAIN_MDU = MDU
"""
The maximum size of the payload data in a single unencrypted packet
"""
TIMEOUT_PER_HOP = RNS.Reticulum.DEFAULT_PER_HOP_TIMEOUT
def __init__(self, destination, data, packet_type = DATA, context = NONE, transport_type = RNS.Transport.BROADCAST, header_type = HEADER_1, transport_id = None, attached_interface = None, create_receipt = True):
if destination != None:
if transport_type == None:
transport_type = RNS.Transport.BROADCAST
self.header_type = header_type
self.packet_type = packet_type
self.transport_type = transport_type
self.context = context
self.hops = 0;
self.destination = destination
self.transport_id = transport_id
self.data = data
self.flags = self.get_packed_flags()
self.raw = None
self.packed = False
self.sent = False
self.create_receipt = create_receipt
self.receipt = None
self.fromPacked = False
else:
self.raw = data
self.packed = True
self.fromPacked = True
self.create_receipt = False
self.MTU = RNS.Reticulum.MTU
self.sent_at = None
self.packet_hash = None
self.attached_interface = attached_interface
self.receiving_interface = None
self.rssi = None
self.snr = None
self.q = None
def get_packed_flags(self):
if self.context == Packet.LRPROOF:
packed_flags = (self.header_type << 6) | (self.transport_type << 4) | (RNS.Destination.LINK << 2) | self.packet_type
else:
packed_flags = (self.header_type << 6) | (self.transport_type << 4) | (self.destination.type << 2) | self.packet_type
return packed_flags
def pack(self):
self.destination_hash = self.destination.hash
self.header = b""
self.header += struct.pack("!B", self.flags)
self.header += struct.pack("!B", self.hops)
if self.context == Packet.LRPROOF:
self.header += self.destination.link_id
self.ciphertext = self.data
else:
if self.header_type == Packet.HEADER_1:
self.header += self.destination.hash
if self.packet_type == Packet.ANNOUNCE:
# Announce packets are not encrypted
self.ciphertext = self.data
elif self.packet_type == Packet.LINKREQUEST:
# Link request packets are not encrypted
self.ciphertext = self.data
elif self.packet_type == Packet.PROOF and self.context == Packet.RESOURCE_PRF:
# Resource proofs are not encrypted
self.ciphertext = self.data
elif self.packet_type == Packet.PROOF and self.destination.type == RNS.Destination.LINK:
# Packet proofs over links are not encrypted
self.ciphertext = self.data
elif self.context == Packet.RESOURCE:
# A resource takes care of encryption
# by itself
self.ciphertext = self.data
elif self.context == Packet.KEEPALIVE:
# Keepalive packets contain no actual
# data
self.ciphertext = self.data
elif self.context == Packet.CACHE_REQUEST:
# Cache-requests are not encrypted
self.ciphertext = self.data
else:
# In all other cases, we encrypt the packet
# with the destination's encryption method
self.ciphertext = self.destination.encrypt(self.data)
if self.header_type == Packet.HEADER_2:
if self.transport_id != None:
self.header += self.transport_id
self.header += self.destination.hash
if self.packet_type == Packet.ANNOUNCE:
# Announce packets are not encrypted
self.ciphertext = self.data
else:
raise IOError("Packet with header type 2 must have a transport ID")
self.header += bytes([self.context])
self.raw = self.header + self.ciphertext
if len(self.raw) > self.MTU:
raise IOError("Packet size of "+str(len(self.raw))+" exceeds MTU of "+str(self.MTU)+" bytes")
self.packed = True
self.update_hash()
def unpack(self):
try:
self.flags = self.raw[0]
self.hops = self.raw[1]
self.header_type = (self.flags & 0b01000000) >> 6
self.transport_type = (self.flags & 0b00110000) >> 4
self.destination_type = (self.flags & 0b00001100) >> 2
self.packet_type = (self.flags & 0b00000011)
DST_LEN = RNS.Reticulum.TRUNCATED_HASHLENGTH//8
if self.header_type == Packet.HEADER_2:
self.transport_id = self.raw[2:DST_LEN+2]
self.destination_hash = self.raw[DST_LEN+2:2*DST_LEN+2]
self.context = ord(self.raw[2*DST_LEN+2:2*DST_LEN+3])
self.data = self.raw[2*DST_LEN+3:]
else:
self.transport_id = None
self.destination_hash = self.raw[2:DST_LEN+2]
self.context = ord(self.raw[DST_LEN+2:DST_LEN+3])
self.data = self.raw[DST_LEN+3:]
self.packed = False
self.update_hash()
return True
except Exception as e:
RNS.log("Received malformed packet, dropping it. The contained exception was: "+str(e), RNS.LOG_EXTREME)
return False
def send(self):
"""
Sends the packet.
:returns: A :ref:`RNS.PacketReceipt<api-packetreceipt>` instance if *create_receipt* was set to *True* when the packet was instantiated, if not returns *None*. If the packet could not be sent *False* is returned.
"""
if not self.sent:
if self.destination.type == RNS.Destination.LINK:
if self.destination.status == RNS.Link.CLOSED:
raise IOError("Attempt to transmit over a closed link")
else:
self.destination.last_outbound = time.time()
self.destination.tx += 1
self.destination.txbytes += len(self.data)
if not self.packed:
self.pack()
if RNS.Transport.outbound(self):
return self.receipt
else:
RNS.log("No interfaces could process the outbound packet", RNS.LOG_ERROR)
self.sent = False
self.receipt = None
return False
else:
raise IOError("Packet was already sent")
def resend(self):
"""
Re-sends the packet.
:returns: A :ref:`RNS.PacketReceipt<api-packetreceipt>` instance if *create_receipt* was set to *True* when the packet was instantiated, if not returns *None*. If the packet could not be sent *False* is returned.
"""
if self.sent:
# Re-pack the packet to obtain new ciphertext for
# encrypted destinations
self.pack()
if RNS.Transport.outbound(self):
return self.receipt
else:
RNS.log("No interfaces could process the outbound packet", RNS.LOG_ERROR)
self.sent = False
self.receipt = None
return False
else:
raise IOError("Packet was not sent yet")
def prove(self, destination=None):
if self.fromPacked and hasattr(self, "destination") and self.destination:
if self.destination.identity and self.destination.identity.prv:
self.destination.identity.prove(self, destination)
elif self.fromPacked and hasattr(self, "link") and self.link:
self.link.prove_packet(self)
else:
RNS.log("Could not prove packet associated with neither a destination nor a link", RNS.LOG_ERROR)
# Generates a special destination that allows Reticulum
# to direct the proof back to the proved packet's sender
def generate_proof_destination(self):
return ProofDestination(self)
def validate_proof_packet(self, proof_packet):
return self.receipt.validate_proof_packet(proof_packet)
def validate_proof(self, proof):
return self.receipt.validate_proof(proof)
def update_hash(self):
self.packet_hash = self.get_hash()
def get_hash(self):
return RNS.Identity.full_hash(self.get_hashable_part())
def getTruncatedHash(self):
return RNS.Identity.truncated_hash(self.get_hashable_part())
def get_hashable_part(self):
hashable_part = bytes([self.raw[0] & 0b00001111])
if self.header_type == Packet.HEADER_2:
hashable_part += self.raw[(RNS.Identity.TRUNCATED_HASHLENGTH//8)+2:]
else:
hashable_part += self.raw[2:]
return hashable_part
class ProofDestination:
def __init__(self, packet):
self.hash = packet.get_hash()[:RNS.Reticulum.TRUNCATED_HASHLENGTH//8];
self.type = RNS.Destination.SINGLE
def encrypt(self, plaintext):
return plaintext
class PacketReceipt:
"""
The PacketReceipt class is used to receive notifications about
:ref:`RNS.Packet<api-packet>` instances sent over the network. Instances
of this class are never created manually, but always returned from
the *send()* method of a :ref:`RNS.Packet<api-packet>` instance.
"""
# Receipt status constants
FAILED = 0x00
SENT = 0x01
DELIVERED = 0x02
CULLED = 0xFF
EXPL_LENGTH = RNS.Identity.HASHLENGTH//8+RNS.Identity.SIGLENGTH//8
IMPL_LENGTH = RNS.Identity.SIGLENGTH//8
# Creates a new packet receipt from a sent packet
def __init__(self, packet):
self.hash = packet.get_hash()
self.truncated_hash = packet.getTruncatedHash()
self.sent = True
self.sent_at = time.time()
self.proved = False
self.status = PacketReceipt.SENT
self.destination = packet.destination
self.callbacks = PacketReceiptCallbacks()
self.concluded_at = None
self.proof_packet = None
if packet.destination.type == RNS.Destination.LINK:
self.timeout = packet.destination.rtt * packet.destination.traffic_timeout_factor
else:
self.timeout = RNS.Reticulum.get_instance().get_first_hop_timeout(self.destination.hash)
self.timeout += Packet.TIMEOUT_PER_HOP * RNS.Transport.hops_to(self.destination.hash)
def get_status(self):
"""
:returns: The status of the associated :ref:`RNS.Packet<api-packet>` instance. Can be one of ``RNS.PacketReceipt.SENT``, ``RNS.PacketReceipt.DELIVERED``, ``RNS.PacketReceipt.FAILED`` or ``RNS.PacketReceipt.CULLED``.
"""
return self.status
# Validate a proof packet
def validate_proof_packet(self, proof_packet):
if hasattr(proof_packet, "link") and proof_packet.link:
return self.validate_link_proof(proof_packet.data, proof_packet.link, proof_packet)
else:
return self.validate_proof(proof_packet.data, proof_packet)
# Validate a raw proof for a link
def validate_link_proof(self, proof, link, proof_packet=None):
# TODO: Hardcoded as explicit proofs for now
if True or len(proof) == PacketReceipt.EXPL_LENGTH:
# This is an explicit proof
proof_hash = proof[:RNS.Identity.HASHLENGTH//8]
signature = proof[RNS.Identity.HASHLENGTH//8:RNS.Identity.HASHLENGTH//8+RNS.Identity.SIGLENGTH//8]
if proof_hash == self.hash:
proof_valid = link.validate(signature, self.hash)
if proof_valid:
self.status = PacketReceipt.DELIVERED
self.proved = True
self.concluded_at = time.time()
self.proof_packet = proof_packet
link.last_proof = self.concluded_at
if self.callbacks.delivery != None:
try:
self.callbacks.delivery(self)
except Exception as e:
RNS.log("An error occurred while evaluating external delivery callback for "+str(link), RNS.LOG_ERROR)
RNS.log("The contained exception was: "+str(e), RNS.LOG_ERROR)
return True
else:
return False
else:
return False
elif len(proof) == PacketReceipt.IMPL_LENGTH:
pass
# TODO: Why is this disabled?
# signature = proof[:RNS.Identity.SIGLENGTH//8]
# proof_valid = self.link.validate(signature, self.hash)
# if proof_valid:
# self.status = PacketReceipt.DELIVERED
# self.proved = True
# self.concluded_at = time.time()
# if self.callbacks.delivery != None:
# self.callbacks.delivery(self)
# RNS.log("valid")
# return True
# else:
# RNS.log("invalid")
# return False
else:
return False
# Validate a raw proof
def validate_proof(self, proof, proof_packet=None):
if len(proof) == PacketReceipt.EXPL_LENGTH:
# This is an explicit proof
proof_hash = proof[:RNS.Identity.HASHLENGTH//8]
signature = proof[RNS.Identity.HASHLENGTH//8:RNS.Identity.HASHLENGTH//8+RNS.Identity.SIGLENGTH//8]
if proof_hash == self.hash:
proof_valid = self.destination.identity.validate(signature, self.hash)
if proof_valid:
self.status = PacketReceipt.DELIVERED
self.proved = True
self.concluded_at = time.time()
self.proof_packet = proof_packet
if self.callbacks.delivery != None:
try:
self.callbacks.delivery(self)
except Exception as e:
RNS.log("Error while executing proof validated callback. The contained exception was: "+str(e), RNS.LOG_ERROR)
return True
else:
return False
else:
return False
elif len(proof) == PacketReceipt.IMPL_LENGTH:
# This is an implicit proof
if self.destination.identity == None:
return False
signature = proof[:RNS.Identity.SIGLENGTH//8]
proof_valid = self.destination.identity.validate(signature, self.hash)
if proof_valid:
self.status = PacketReceipt.DELIVERED
self.proved = True
self.concluded_at = time.time()
self.proof_packet = proof_packet
if self.callbacks.delivery != None:
try:
self.callbacks.delivery(self)
except Exception as e:
RNS.log("Error while executing proof validated callback. The contained exception was: "+str(e), RNS.LOG_ERROR)
return True
else:
return False
else:
return False
def get_rtt(self):
"""
:returns: The round-trip-time in seconds
"""
return self.concluded_at - self.sent_at
def is_timed_out(self):
return (self.sent_at+self.timeout < time.time())
def check_timeout(self):
if self.status == PacketReceipt.SENT and self.is_timed_out():
if self.timeout == -1:
self.status = PacketReceipt.CULLED
else:
self.status = PacketReceipt.FAILED
self.concluded_at = time.time()
if self.callbacks.timeout:
thread = threading.Thread(target=self.callbacks.timeout, args=(self,))
thread.daemon = True
thread.start()
def set_timeout(self, timeout):
"""
Sets a timeout in seconds
:param timeout: The timeout in seconds.
"""
self.timeout = float(timeout)
def set_delivery_callback(self, callback):
"""
Sets a function that gets called if a successfull delivery has been proven.
:param callback: A *callable* with the signature *callback(packet_receipt)*
"""
self.callbacks.delivery = callback
# Set a function that gets called if the
# delivery times out
def set_timeout_callback(self, callback):
"""
Sets a function that gets called if the delivery times out.
:param callback: A *callable* with the signature *callback(packet_receipt)*
"""
self.callbacks.timeout = callback
class PacketReceiptCallbacks:
def __init__(self):
self.delivery = None
self.timeout = None
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