import struct import FPE class Packet: # Constants MESSAGE = 0x00; RESOURCE = 0x01; LINKREQUEST = 0x02; PROOF = 0x03; types = [MESSAGE, RESOURCE, LINKREQUEST, PROOF] 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] 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 self.header_type = header_type self.packet_type = packet_type self.transport_type = transport_type 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) 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")