Reticulum/FPE/Packet.py

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import struct
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import FPE
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class Packet:
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# Constants
MESSAGE = 0x00;
RESOURCE = 0x01;
LINKREQUEST = 0x02;
PROOF = 0x03;
types = [MESSAGE, RESOURCE, LINKREQUEST, PROOF]
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HEADER_1 = 0x00; # Normal header format
HEADER_2 = 0x01; # Header format used for link packets in transport
HEADER_3 = 0x02; # Reserved
HEADER_4 = 0x03; # Reserved
header_types = [HEADER_1, HEADER_2, HEADER_3, HEADER_4]
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def __init__(self, destination, data, packet_type = MESSAGE, transport_type = None, header_type = HEADER_1, transport_id = None):
if destination != None:
if transport_type == None:
transport_type = FPE.Transport.BROADCAST
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self.header_type = header_type
self.packet_type = packet_type
self.transport_type = transport_type
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self.hops = 0;
self.destination = destination
self.transport_id = transport_id
self.data = data
self.flags = self.getPackedFlags()
self.raw = None
self.packed = False
self.sent = False
self.MTU = self.destination.MTU
else:
self.raw = data
self.packed = True
def getPackedFlags(self):
packed_flags = (self.header_type << 6) | (self.transport_type << 4) | (self.destination.type << 2) | self.packet_type
return packed_flags
def pack(self):
self.header = ""
self.header += struct.pack("!B", self.flags)
self.header += struct.pack("!B", self.hops)
if self.header_type == Packet.HEADER_2:
if t_destination != None:
self.header += self.t_destination
else:
raise IOError("Packet with header type 2 must have a transport ID")
self.header += self.destination.hash
self.ciphertext = self.destination.encrypt(self.data)
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
def unpack(self):
self.flags = ord(self.raw[0])
self.hops = ord(self.raw[1])
self.header_type = (self.flags & 0b11000000) >> 6
self.transport_type = (self.flags & 0b00110000) >> 4
self.destination_type = (self.flags & 0b00001100) >> 2
self.packet_type = (self.flags & 0b00000011)
if self.header_type == Packet.HEADER_2:
self.transport_id = self.raw[2:12]
self.destination_hash = self.raw[12:22]
self.data = self.raw[22:]
else:
self.transport_id = None
self.destination_hash = self.raw[2:12]
self.data = self.raw[12:]
self.packed = False
def send(self):
if not self.sent:
self.pack()
FPE.log("Size: "+str(len(self.raw))+" header is "+str(len(self.header))+" payload is "+str(len(self.ciphertext)), FPE.LOG_DEBUG)
FPE.Transport.outbound(self.raw)
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self.sent = True
else:
raise IOError("Packet was already sent")
def resend(self):
if self.sent:
Transport.outbound(self.raw)
else:
raise IOError("Packet was not sent yet")