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"""
tcpdump capture file
"""
from construct_legacy import *
import time
from datetime import datetime
class MicrosecAdapter(Adapter):
def _decode(self, obj, context):
return datetime.fromtimestamp(obj[0] + (obj[1] / 1000000.0))
def _encode(self, obj, context):
offset = time.mktime(*obj.timetuple())
sec = int(offset)
usec = (offset - sec) * 1000000
return (sec, usec)
packet = Struct("packet",
MicrosecAdapter(
Sequence("time",
ULInt32("time"),
ULInt32("usec"),
)
),
ULInt32("length"),
Padding(4),
HexDumpAdapter(Field("data", lambda ctx: ctx.length)),
)
cap_file = Struct("cap_file",
Padding(24),
Rename("packets", OptionalGreedyRange(packet)),
)
if __name__ == "__main__":
obj = cap_file.parse_stream(open("../../tests/cap2.cap", "rb"))
print(len(obj.packets))
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