mirror of
https://github.com/espressif/openthread.git
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Yakun Xu
70 lines
2.2 KiB
Python
70 lines
2.2 KiB
Python
#
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# Copyright (c) 2018, The OpenThread Authors.
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# All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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""" Module to provide codec utilities for .pcap formatters. """
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import struct
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import time
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DLT_IEEE802_15_4 = 195
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PCAP_MAGIC_NUMBER = 0xa1b2c3d4
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PCAP_VERSION_MAJOR = 2
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PCAP_VERSION_MINOR = 4
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class PcapCodec(object):
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""" Utility class for .pcap formatters. """
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def __init__(self, filename):
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self._pcap_file = open('%s.pcap' % filename, 'wb')
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self._pcap_file.write(self.encode_header())
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self._epoch = time.time()
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def encode_header(self):
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""" Returns a pcap file header. """
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return struct.pack("<LHHLLLL",
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PCAP_MAGIC_NUMBER,
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PCAP_VERSION_MAJOR,
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PCAP_VERSION_MINOR,
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0, 0, 256,
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DLT_IEEE802_15_4)
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def encode_frame(self, frame, sec, usec):
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""" Returns a pcap encapsulation of the given frame. """
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frame = frame[1:]
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length = len(frame)
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pcap_frame = struct.pack("<LLLL", sec, usec, length, length)
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pcap_frame += frame
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return pcap_frame
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def _get_timestamp(self):
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""" Returns the internal timestamp. """
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timestamp = time.time() - self._epoch
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timestamp_sec = int(timestamp)
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timestamp_usec = int((timestamp - timestamp_sec) * 1000000)
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return timestamp_sec, timestamp_usec
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def append(self, frame, timestamp=None):
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""" Appends a frame. """
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if timestamp is None:
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timestamp = self._get_timestamp()
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pkt = self.encode_frame(frame, *timestamp)
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self._pcap_file.write(pkt)
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def __del__(self):
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self._pcap_file.close()
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