def decode_packet(data):
"""decode the data, return some kind of PDU."""
if _debug: decode_packet._debug("decode_packet %r", data)
# convert the hex data to an octet string
data = ''.join(chr(int(data[i:i + 2], 16)) for i in range(0, len(data), 2))
# build a PDU
pdu = PDU(data)
# check for a BVLL header
if (pdu.pduData[0] == '\x81'):
if _debug: decode_packet._debug(" - BVLL header found")
xpdu = BVLPDU()
xpdu.decode(pdu)
if _debug: decode_packet._debug(" - xpdu: %r", xpdu)
pdu = xpdu
# make a more focused interpretation
atype = bvl_pdu_types.get(pdu.bvlciFunction)
if not atype:
if _debug:
decode_packet._debug(" - unknown BVLL type: %r",
pdu.bvlciFunction)
return pdu
# decode it as one of the basic types
try:
xpdu = pdu
bpdu = atype()
bpdu.decode(pdu)
if _debug: decode_packet._debug(" - bpdu: %r", bpdu)
pdu = bpdu
# lift the address for forwarded NPDU's
if atype is ForwardedNPDU:
pdu.pduSource = bpdu.bvlciAddress
# no deeper decoding for some
elif atype not in (DistributeBroadcastToNetwork,
OriginalUnicastNPDU, OriginalBroadcastNPDU):
return pdu
except Exception, err:
if _debug: decode_packet._debug(" - decoding Error: %r", err)
return xpdu
def decode_packet(data, destination):
"""decode the data, return some kind of PDU."""
if _debug:
decode_packet._debug("decode_packet %r %r", data, destination)
# build a PDU
pdu = PDU(data, destination=destination)
# check for a BVLL header
if pdu.pduData[0] == 0x84:
if _debug:
decode_packet._debug(" - BVLL header found")
xpdu = BVLPDU()
xpdu.decode(pdu)
pdu = xpdu
# make a more focused interpretation
atype = bvl_pdu_types.get(pdu.bvlciFunction)
if not atype:
if _debug:
decode_packet._debug(" - unknown BVLL type: %r", pdu.bvlciFunction)
return pdu
# decode it as one of the basic types
try:
xpdu = pdu
bpdu = atype()
bpdu.decode(pdu)
if _debug:
decode_packet._debug(" - bpdu: %r", bpdu)
pdu = bpdu
# source address in the packet
pdu.pduSource = pdu.bvlciAddress
# no deeper decoding for some
if atype not in (OriginalUnicastNPDU, OriginalBroadcastNPDU):
return pdu
except Exception as err:
if _debug:
decode_packet._debug(" - decoding Error: %r", err)
return xpdu
# check for version number
if pdu.pduData[0] != 0x01:
if _debug:
decode_packet._debug(
" - not a version 1 packet: %s...", btox(pdu.pduData[:30], ".")
)
return None
# it's an NPDU
try:
npdu = NPDU()
npdu.decode(pdu)
except Exception as err:
if _debug:
decode_packet._debug(" - decoding Error: %r", err)
return None
# application or network layer message
if npdu.npduNetMessage is None:
if _debug:
decode_packet._debug(" - not a network layer message, try as an APDU")
# decode as a generic APDU
try:
xpdu = APDU()
xpdu.decode(npdu)
apdu = xpdu
except Exception as err:
if _debug:
decode_packet._debug(" - decoding Error: %r", err)
return npdu
# "lift" the source and destination address
if npdu.npduSADR:
apdu.pduSource = npdu.npduSADR
else:
apdu.pduSource = npdu.pduSource
if npdu.npduDADR:
apdu.pduDestination = npdu.npduDADR
else:
apdu.pduDestination = npdu.pduDestination
# make a more focused interpretation
atype = apdu_types.get(apdu.apduType)
if not atype:
if _debug:
decode_packet._debug(" - unknown APDU type: %r", apdu.apduType)
return apdu
# decode it as one of the basic types
try:
xpdu = apdu
apdu = atype()
apdu.decode(xpdu)
except Exception as err:
if _debug:
decode_packet._debug(" - decoding Error: %r", err)
return xpdu
# decode it at the next level
if isinstance(apdu, ConfirmedRequestPDU):
atype = confirmed_request_types.get(apdu.apduService)
if not atype:
if _debug:
decode_packet._debug(
" - no confirmed request decoder: %r", apdu.apduService
)
return apdu
elif isinstance(apdu, UnconfirmedRequestPDU):
atype = unconfirmed_request_types.get(apdu.apduService)
if not atype:
if _debug:
decode_packet._debug(
" - no unconfirmed request decoder: %r", apdu.apduService
)
return apdu
elif isinstance(apdu, SimpleAckPDU):
atype = None
elif isinstance(apdu, ComplexAckPDU):
atype = complex_ack_types.get(apdu.apduService)
if not atype:
if _debug:
decode_packet._debug(
" - no complex ack decoder: %r", apdu.apduService
)
return apdu
elif isinstance(apdu, SegmentAckPDU):
atype = None
elif isinstance(apdu, ErrorPDU):
atype = error_types.get(apdu.apduService)
if not atype:
if _debug:
decode_packet._debug(" - no error decoder: %r", apdu.apduService)
return apdu
elif isinstance(apdu, RejectPDU):
atype = None
elif isinstance(apdu, AbortPDU):
atype = None
if _debug:
decode_packet._debug(" - atype: %r", atype)
# deeper decoding
try:
if atype:
xpdu = apdu
apdu = atype()
apdu.decode(xpdu)
except Exception as err:
if _debug:
decode_packet._debug(" - decoding error: %r", err)
return xpdu
# success
return apdu
else:
# make a more focused interpretation
ntype = npdu_types.get(npdu.npduNetMessage)
if not ntype:
if _debug:
decode_packet._debug(
" - no network layer decoder: %r", npdu.npduNetMessage
)
return npdu
if _debug:
decode_packet._debug(" - ntype: %r", ntype)
# deeper decoding
try:
xpdu = npdu
npdu = ntype()
npdu.decode(xpdu)
except Exception as err:
if _debug:
decode_packet._debug(" - decoding error: %r", err)
return xpdu
# success
return npdu
