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Fix payload_len calculation for DataPacket. #4545

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Merged
merged 1 commit into from
Nov 2, 2025
Merged

Fix payload_len calculation for DataPacket. #4545

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3 changes: 2 additions & 1 deletion scapy/contrib/rtps/common_types.py
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Original file line number Diff line number Diff line change
Expand Up @@ -161,7 +161,8 @@ class SerializedDataField(StrLenField):
class DataPacketField(EPacketField):
def m2i(self, pkt, m):
self.set_endianness(pkt)
pl_len = pkt.octetsToNextHeader - 24
fld, val = pkt.getfield_and_val("inlineQoS")
pl_len = pkt.octetsToNextHeader - 24 - fld.i2len(pkt, val)
_pkt = self.cls(
m,
endianness=self.endianness,
Expand Down
3 changes: 2 additions & 1 deletion scapy/contrib/rtps/rtps.py
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Expand Up @@ -197,7 +197,8 @@ def __init__(self, *args, **kwargs):
writer_entity_id_key = kwargs.pop("writer_entity_id_key", None)
writer_entity_id_kind = kwargs.pop("writer_entity_id_kind", None)
pl_len = kwargs.pop("pl_len", 0)
if writer_entity_id_key == 0x200 and writer_entity_id_kind == 0xC2:
if (writer_entity_id_key == 0x200 or writer_entity_id_key == 0x100) and \
writer_entity_id_kind == 0xC2:
DataPacket._pl_type = "ParticipantMessageData"
else:
DataPacket._pl_type = "SerializedData"
Expand Down
104 changes: 103 additions & 1 deletion test/contrib/rtps.uts
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Original file line number Diff line number Diff line change
Expand Up @@ -404,7 +404,6 @@ p1 = RTPS(
)
assert p0.build() == d
assert p1.build() == d
assert p1 == p0

+ Test for pr #3914
= RTPS Heartbeat SequenceNumber_t packing and dissection
Expand Down Expand Up @@ -476,3 +475,106 @@ p1 = RTPS(
assert p0.build() == d
assert p1.build() == d
assert p0 == p1

+ Test for #PR4545
= RTPS length computation with inlineQos

p0 = RTPS(
protocolVersion=ProtocolVersionPacket(major=2, minor=2),
vendorId=VendorIdPacket(vendor_id=0x010f),
guidPrefix=GUIDPrefixPacket(
hostId=0x010f45d2, appId=0xb3f558b9, instanceId=0x01000000
),magic=b"RTPS"
)/RTPSMessage(submessages=[
RTPSSubMessage_INFO_TS(
submessageId=9,
submessageFlags=1,
octetsToNextHeader=8,
ts_seconds=1638425814,
ts_fraction=2083784982,
),
RTPSSubMessage_DATA(
submessageId= 0x15,
submessageFlags= 0x7,
octetsToNextHeader= 54,
extraFlags= 0x0,
octetsToInlineQoS= 16,
readerEntityIdKey= 0x0,
readerEntityIdKind= 0x0,
writerEntityIdKey= 0x0,
writerEntityIdKind= 0x0,
writerSeqNumHi= 0,
writerSeqNumLow= 4,
inlineQoS= InlineQoSPacket(
parameters= [
PID_UNKNOWN(
parameterId= 0x801e,
parameterLength= 4,
parameterData= b'\x00\x00\x00\x00',
),
],
sentinel= PID_SENTINEL(
parameterId= 0x1,
parameterLength= 0,
parameterData= b'',
),
),
data= DataPacket(
encapsulationKind= 0x1,
encapsulationOptions= 0x3,
serializedData= b'=\x00\x00\x00abcdefghij\x00\x00\x00\x00',
),
),
RTPSSubMessage_INFO_TS(
submessageId=9,
submessageFlags=1,
octetsToNextHeader=8,
ts_seconds=1638425814,
ts_fraction=2083784982,
),
RTPSSubMessage_DATA(
submessageId= 0x15,
submessageFlags= 0x7,
octetsToNextHeader= 54,
extraFlags= 0x0,
octetsToInlineQoS= 16,
readerEntityIdKey= 0x0,
readerEntityIdKind= 0x0,
writerEntityIdKey= 0x0,
writerEntityIdKind= 0x0,
writerSeqNumHi= 0,
writerSeqNumLow= 4,
inlineQoS= InlineQoSPacket(
parameters= [
PID_UNKNOWN(
parameterId= 0x801e,
parameterLength= 4,
parameterData= b'\x00\x00\x00\x00',
),
],
sentinel= PID_SENTINEL(
parameterId= 0x1,
parameterLength= 0,
parameterData= b'',
),
),
data= DataPacket(
encapsulationKind= 0x1,
encapsulationOptions= 0x3,
serializedData= b'=\x00\x00\x00abcdefghij\x00\x00\x00\x00',
),
),
])

d = b"\x52\x54\x50\x53\x02\x02\x01\x0f\x01\x0f\x45\xd2\xb3\xf5\x58\xb9" \
b"\x01\x00\x00\x00\x09\x01\x08\x00\xd6\x64\xa8\x61\x16\x09\x34\x7c" \
b"\x15\x07\x36\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00" \
b"\x00\x00\x00\x00\x04\x00\x00\x00\x1e\x80\x04\x00\x00\x00\x00\x00" \
b"\x01\x00\x00\x00\x00\x01\x00\x03\x3d\x00\x00\x00\x61\x62\x63\x64" \
b"\x65\x66\x67\x68\x69\x6a\x00\x00\x00\x00\x09\x01\x08\x00\xd6\x64" \
b"\xa8\x61\x16\x09\x34\x7c\x15\x07\x36\x00\x00\x00\x10\x00\x00\x00" \
b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x1e\x80" \
b"\x04\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x01\x00\x03\x3d\x00" \
b"\x00\x00\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x00\x00\x00\x00"

assert RTPS(d) == p0