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Fix MCS alignment #2771

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Merged
p-l- merged 1 commit into from
Aug 17, 2020
Merged

Fix MCS alignment #2771

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123 changes: 66 additions & 57 deletions scapy/layers/dot11.py
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,6 @@
"""

from __future__ import print_function
import math
import re
import struct
from zlib import crc32
Expand Down Expand Up @@ -147,22 +146,8 @@ def answers(self, other):

# https://www.radiotap.org/


class _RadiotapReversePadField(ReversePadField):
def __init__(self, fld):
# Quote from https://www.radiotap.org/:
# ""Radiotap requires that all fields in the radiotap header are aligned to natural boundaries. # noqa: E501
# For radiotap, that means all 8-, 16-, 32-, and 64-bit fields must begin on 8-, 16-, 32-, and 64-bit boundaries, respectively."" # noqa: E501
if isinstance(fld, BitField):
_align = int(math.ceil(fld.i2len(None, None)))
else:
_align = struct.calcsize(fld.fmt)
ReversePadField.__init__(
self,
fld,
_align,
padwith=b"\x00"
)
# Note: Radiotap alignment is crazy. See the doc:
# https://www.radiotap.org/#alignment-in-radiotap


def _next_radiotap_extpm(pkt, lst, cur, s):
Expand Down Expand Up @@ -287,68 +272,76 @@ class RadioTap(Packet):
FlagsField('present', None, -32, _rt_present), # noqa: E501
# Extended presence mask
ConditionalField(PacketListField("Ext", [], next_cls_cb=_next_radiotap_extpm), lambda pkt: pkt.present and pkt.present.Ext), # noqa: E501
# RadioTap fields - each starts with a _RadiotapReversePadField
# RadioTap fields - each starts with a ReversePadField
# to handle padding

# TSFT
ConditionalField(
_RadiotapReversePadField(
LELongField("mac_timestamp", 0)
ReversePadField(
LELongField("mac_timestamp", 0),
8
),
lambda pkt: pkt.present and pkt.present.TSFT),
# Flags
ConditionalField(
_RadiotapReversePadField(
FlagsField("Flags", None, -8, _rt_flags)
),
FlagsField("Flags", None, -8, _rt_flags),
lambda pkt: pkt.present and pkt.present.Flags),
# Rate
ConditionalField(
_RadiotapReversePadField(
ScalingField("Rate", 0, scaling=0.5,
unit="Mbps", fmt="B")),
ScalingField("Rate", 0, scaling=0.5,
unit="Mbps", fmt="B"),
lambda pkt: pkt.present and pkt.present.Rate),
# Channel
ConditionalField(
_RadiotapReversePadField(LEShortField("ChannelFrequency", 0)),
ReversePadField(
LEShortField("ChannelFrequency", 0),
2
),
lambda pkt: pkt.present and pkt.present.Channel),
ConditionalField(
FlagsField("ChannelFlags", None, -16, _rt_channelflags),
lambda pkt: pkt.present and pkt.present.Channel),
# dBm_AntSignal
ConditionalField(
_RadiotapReversePadField(
ScalingField("dBm_AntSignal", 0, offset=-256,
unit="dBm", fmt="B")),
ScalingField("dBm_AntSignal", 0, offset=-256,
unit="dBm", fmt="B"),
lambda pkt: pkt.present and pkt.present.dBm_AntSignal),
# dBm_AntNoise
ConditionalField(
_RadiotapReversePadField(
ScalingField("dBm_AntNoise", 0, offset=-256,
unit="dBm", fmt="B")),
ScalingField("dBm_AntNoise", 0, offset=-256,
unit="dBm", fmt="B"),
lambda pkt: pkt.present and pkt.present.dBm_AntNoise),
# Lock_Quality
ConditionalField(
_RadiotapReversePadField(LEShortField("Lock_Quality", 0)),
ReversePadField(
LEShortField("Lock_Quality", 0),
2
),
lambda pkt: pkt.present and pkt.present.Lock_Quality),
# Antenna
ConditionalField(
_RadiotapReversePadField(ByteField("Antenna", 0)),
ByteField("Antenna", 0),
lambda pkt: pkt.present and pkt.present.Antenna),
# RX Flags
ConditionalField(
_RadiotapReversePadField(
FlagsField("RXFlags", None, -16, _rt_rxflags)),
ReversePadField(
FlagsField("RXFlags", None, -16, _rt_rxflags),
2
),
lambda pkt: pkt.present and pkt.present.RXFlags),
# TX Flags
ConditionalField(
_RadiotapReversePadField(
FlagsField("TXFlags", None, -16, _rt_txflags)),
ReversePadField(
FlagsField("TXFlags", None, -16, _rt_txflags),
2
),
lambda pkt: pkt.present and pkt.present.TXFlags),
# ChannelPlus
ConditionalField(
_RadiotapReversePadField(
FlagsField("ChannelPlusFlags", None, -32, _rt_channelflags2)),
ReversePadField(
FlagsField("ChannelPlusFlags", None, -32, _rt_channelflags2),
4
),
lambda pkt: pkt.present and pkt.present.ChannelPlus),
ConditionalField(
LEShortField("ChannelPlusFrequency", 0),
Expand All @@ -358,8 +351,10 @@ class RadioTap(Packet):
lambda pkt: pkt.present and pkt.present.ChannelPlus),
# MCS
ConditionalField(
_RadiotapReversePadField(
FlagsField("knownMCS", None, -8, _rt_knownmcs)),
ReversePadField(
FlagsField("knownMCS", None, -8, _rt_knownmcs),
4
),
lambda pkt: pkt.present and pkt.present.MCS),
ConditionalField(
BitField("Ness_LSB", 0, 1),
Expand All @@ -384,16 +379,20 @@ class RadioTap(Packet):
lambda pkt: pkt.present and pkt.present.MCS),
# A_MPDU
ConditionalField(
_RadiotapReversePadField(
LEIntField("A_MPDU_ref", 0)),
ReversePadField(
LEIntField("A_MPDU_ref", 0),
4
),
lambda pkt: pkt.present and pkt.present.A_MPDU),
ConditionalField(
FlagsField("A_MPDU_flags", None, -32, _rt_a_mpdu_flags),
lambda pkt: pkt.present and pkt.present.A_MPDU),
# VHT
ConditionalField(
_RadiotapReversePadField(
FlagsField("KnownVHT", None, -16, _rt_knownvht)),
ReversePadField(
FlagsField("KnownVHT", None, -16, _rt_knownvht),
2
),
lambda pkt: pkt.present and pkt.present.VHT),
ConditionalField(
FlagsField("PresentVHT", None, -8, _rt_presentvht),
Expand All @@ -412,8 +411,10 @@ class RadioTap(Packet):
lambda pkt: pkt.present and pkt.present.VHT),
# timestamp
ConditionalField(
_RadiotapReversePadField(
LELongField("timestamp", 0)),
ReversePadField(
LELongField("timestamp", 0),
8
),
lambda pkt: pkt.present and pkt.present.timestamp),
ConditionalField(
LEShortField("ts_accuracy", 0),
Expand All @@ -426,8 +427,10 @@ class RadioTap(Packet):
lambda pkt: pkt.present and pkt.present.timestamp),
# HE - XXX not complete
ConditionalField(
_RadiotapReversePadField(
ShortField("he_data1", 0)),
ReversePadField(
ShortField("he_data1", 0),
2
),
lambda pkt: pkt.present and pkt.present.HE),
ConditionalField(
ShortField("he_data2", 0),
Expand All @@ -446,8 +449,10 @@ class RadioTap(Packet):
lambda pkt: pkt.present and pkt.present.HE),
# HE_MU
ConditionalField(
_RadiotapReversePadField(
LEShortField("hemu_flags1", 0)),
ReversePadField(
LEShortField("hemu_flags1", 0),
2
),
lambda pkt: pkt.present and pkt.present.HE_MU),
ConditionalField(
LEShortField("hemu_flags2", 0),
Expand All @@ -462,8 +467,10 @@ class RadioTap(Packet):
lambda pkt: pkt.present and pkt.present.HE_MU),
# HE_MU_other_user
ConditionalField(
_RadiotapReversePadField(
LEShortField("hemuou_per_user_1", 0x7fff)),
ReversePadField(
LEShortField("hemuou_per_user_1", 0x7fff),
2
),
lambda pkt: pkt.present and pkt.present.HE_MU_other_user),
ConditionalField(
LEShortField("hemuou_per_user_2", 0x003f),
Expand All @@ -477,8 +484,10 @@ class RadioTap(Packet):
lambda pkt: pkt.present and pkt.present.HE_MU_other_user),
# L_SIG
ConditionalField(
_RadiotapReversePadField(
FlagsField("lsig_data1", 0, -16, ["rate", "length"])),
ReversePadField(
FlagsField("lsig_data1", 0, -16, ["rate", "length"]),
2
),
lambda pkt: pkt.present and pkt.present.L_SIG),
ConditionalField(
BitField("lsig_length", 0, 12),
Expand Down
12 changes: 12 additions & 0 deletions test/regression.uts
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Original file line number Diff line number Diff line change
Expand Up @@ -12433,6 +12433,18 @@ assert f.ASEL.Explicit_CSI_Feedback_Based_Transmit_ASEL
assert f.ASEL.Antenna_Selection
assert f.ASEL == 63

= RadioTap - MCS weird padding
f = RadioTap(b'\x00\x00,\x00K\x08\x1c\x00"b\x96\x03\x00\x00\x00\x00\x10\x00l\t\x80\x04\xb0\x00\x80\x04\x01\x00l\t\x01\x00\x1f\x08\x0c\x00\x94\x05\x00\x00\x04\x00\x00\x00\x88\x020\x00.\xdf\xc4J\xb0\xdc\xa0c\x91sf\xech\x05\xca?\xf4h@Y\x00\x00\xaa\xaa\x03\x00\x00\x00\x08\x00E\x00\x05\xdc \xcf@\x00\x80\x06P\xf0\xc0\xa8\x01\n\xc0\xa8\x01\x02\xdb\x8f\x13\x89\xfbv\xa3\xde\xf6\xd8L\xe8P\x10\xff\xfft\xdd\x00\x0023456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901O\xdc\x01x')
assert f.knownMCS == 31
assert f.Ness_LSB == 0
assert f.STBC_streams == 0
assert f.FEC_type == 0
assert f.HT_format == 1
assert f.guard_interval == 0
assert f.MCS_bandwidth == 0
assert f.MCS_index == 0xc
assert f.A_MPDU_ref == 1428

= Reassociation request
f = Dot11(b' \x00:\x01@\xe3\xd6\x7f*\x00\x00\x10\x18\xa9l.@\xe3\xd6\x7f*\x00 \t1\x04\n\x00@\xe3\xd6\x7f*\x00\x00\x064.2.12\x01\x08\x82\x84\x0b\x16$0Hl!\x02\x08\x1a$\x02\x01\x0b0&\x01\x00\x00\x0f\xac\x04\x01\x00\x00\x0f\xac\x04\x01\x00\x00\x0f\xac\x01\x00\x00\x01\x00LD\xfe\xf2l\xdcV\xce\x0b7\xab\xc62\x02O\x112\x04\x0c\x12\x18`\x7f\x08\x01\x00\x00\x00\x00\x00\x00@\xdd\t\x00\x10\x18\x02\x00\x00\x10\x00\x00')
assert Dot11EltRSN in f
Expand Down