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## This file is (hopefully) part of Scapy
## See http://www.secdev.org/projects/scapy for more informations
## <jellch@harris.com>
## This program is published under a GPLv2 license
# scapy.contrib.description = PPI
# scapy.contrib.status = loads
"""
PPI (Per-Packet Information).
"""
import logging,struct
from scapy.config import conf
from scapy.packet import *
from scapy.fields import *
from scapy.layers.l2 import Ether
from scapy.layers.dot11 import Dot11
# Dictionary to map the TLV type to the class name of a sub-packet
_ppi_types = {}
def addPPIType(id, value):
_ppi_types[id] = value
def getPPIType(id, default="default"):
return _ppi_types.get(id, _ppi_types.get(default, None))
# Default PPI Field Header
class PPIGenericFldHdr(Packet):
name = "PPI Field Header"
fields_desc = [ LEShortField('pfh_type', 0),
FieldLenField('pfh_length', None, length_of="value", fmt='<H', adjust=lambda p,x:x+4),
StrLenField("value", "", length_from=lambda p:p.pfh_length) ]
def extract_padding(self, p):
return "",p
def _PPIGuessPayloadClass(p, **kargs):
""" This function tells the PacketListField how it should extract the
TLVs from the payload. We pass cls only the length string
pfh_len says it needs. If a payload is returned, that means
part of the sting was unused. This converts to a Raw layer, and
the remainder of p is added as Raw's payload. If there is no
payload, the remainder of p is added as out's payload.
"""
if len(p) >= 4:
t,pfh_len = struct.unpack("<HH", p[:4])
# Find out if the value t is in the dict _ppi_types.
# If not, return the default TLV class
cls = getPPIType(t, "default")
pfh_len += 4
out = cls(p[:pfh_len], **kargs)
if (out.payload):
out.payload = conf.raw_layer(out.payload.load)
if (len(p) > pfh_len):
out.payload.payload = conf.padding_layer(p[pfh_len:])
elif (len(p) > pfh_len):
out.payload = conf.padding_layer(p[pfh_len:])
else:
out = conf.raw_layer(p, **kargs)
return out
class PPI(Packet):
name = "PPI Packet Header"
fields_desc = [ ByteField('pph_version', 0),
ByteField('pph_flags', 0),
FieldLenField('pph_len', None, length_of="PPIFieldHeaders", fmt="<H", adjust=lambda p,x:x+8 ),
LEIntField('dlt', None),
PacketListField("PPIFieldHeaders", [], _PPIGuessPayloadClass, length_from=lambda p:p.pph_len-8,) ]
def guess_payload_class(self,payload):
return conf.l2types.get(self.dlt, Packet.guess_payload_class(self, payload))
#Register PPI
addPPIType("default", PPIGenericFldHdr)
conf.l2types.register(192, PPI)
conf.l2types.register_num2layer(192, PPI)
bind_layers(PPI, Dot11, dlt=conf.l2types.get(Dot11))
bind_layers(Dot11, PPI)
bind_layers(PPI, Ether, dlt=conf.l2types.get(Ether))
bind_layers(Dot11, Ether)
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