def decode_interest(self, input: bytearray) -> Name:
"""
Decode an interest packet
:param input: Interest packet in NDN-TLV wire format
:return: Name
"""
decoder = TlvDecoder(input)
decoder.readNestedTlvsStart(Tlv.Interest)
return self.decode_name(decoder)
def decode_heartbeat(self, input: bytearray) -> Name:
"""
Decode a heartbeat packet
:param input: Heartbeat packet in NDN-TLV wire format
:return: Name
"""
decoder = TlvDecoder(input)
decoder.readNestedTlvsStart(self.heartbeatTV)
return self.decode_name(decoder)
def decode_meta_info(self, decoder: TlvDecoder) -> None:
"""
Decode meta info
:param decoder: Decoder
:return: Nothing so far
"""
endOffset = decoder.readNestedTlvsStart(Tlv.MetaInfo)
# Does not yet parse meta data, but:
# Lets the decoder jump over meta data.
decoder.finishNestedTlvs(endOffset)
def decode_name_component(self, decoder: TlvDecoder) -> bytearray:
"""
Decode a name component
:param decoder: Decoder
:return: Value of name component
"""
savePosition = decoder.getOffset()
type = decoder.readVarNumber()
decoder.seek(savePosition)
return decoder.readBlobTlv(type).tobytes()
def decode_data(self, input: bytearray) -> ([bytearray], bytearray):
"""
Decodes a data packet
:param input: Data packet in NDN-TLV wire format
:return: Name and payload
"""
decoder = TlvDecoder(input)
decoder.readNestedTlvsStart(Tlv.Data)
name = self.decode_name(decoder)
self.decode_meta_info(decoder)
payload = decoder.readBlobTlv(Tlv.Content).tobytes()
return (name, payload)
def decode_nack(self, input: bytearray) -> (Name, NackReason):
"""
Decode NACK packet
:param input: Data packet in NDN-TLV wire format
:return: Name
"""
# decode name
name = self.decode_interest(input[13:])
# decode nack reason
decoder = TlvDecoder(input)
decoder.readNestedTlvsStart(Tlv.LpPacket_LpPacket)
decoder.readNestedTlvsStart(Tlv.LpPacket_Nack)
try:
decoder.readNestedTlvsStart(Tlv.LpPacket_NackReason)
wire_reason = decoder.readVarNumber()
reason = self.__nack_reason_enum[wire_reason]
except ValueError:
# happens when nack reason is not specified
reason = NackReason.NOT_SET
return (name, reason)
def decode_name(self, decoder: TlvDecoder) -> Name:
"""
Decode a name
:param decoder: Decoder
:return: Name
"""
endOffset = decoder.readNestedTlvsStart(Tlv.Name)
comps = []
dgest = None
while decoder.getOffset() < endOffset:
if decoder.peekType(Tlv.ImplicitSha256DigestComponent, endOffset):
dgest = decoder.readBlobTlv(Tlv.ImplicitSha256DigestComponent)
dgest = dgest.tobytes()
else:
comps.append(self.decode_name_component(decoder))
decoder.finishNestedTlvs(endOffset)
return Name(suite='ndn2013').__add__(comps).set_digest(dgest)