| #!/usr/bin/env python3 |
| # |
| # Copyright (c) 2018, The OpenThread Authors. |
| # All rights reserved. |
| # |
| # Redistribution and use in source and binary forms, with or without |
| # modification, are permitted provided that the following conditions are met: |
| # 1. Redistributions of source code must retain the above copyright |
| # notice, this list of conditions and the following disclaimer. |
| # 2. Redistributions in binary form must reproduce the above copyright |
| # notice, this list of conditions and the following disclaimer in the |
| # documentation and/or other materials provided with the distribution. |
| # 3. Neither the name of the copyright holder nor the |
| # names of its contributors may be used to endorse or promote products |
| # derived from this software without specific prior written permission. |
| # |
| # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
| # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| # CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| # POSSIBILITY OF SUCH DAMAGE. |
| # |
| """ Module to provide codec utilities for .pcap formatters. """ |
| |
| import struct |
| import time |
| |
| DLT_IEEE802_15_4 = 195 |
| PCAP_MAGIC_NUMBER = 0xA1B2C3D4 |
| PCAP_VERSION_MAJOR = 2 |
| PCAP_VERSION_MINOR = 4 |
| |
| |
| class PcapCodec(object): |
| """ Utility class for .pcap formatters. """ |
| |
| def __init__(self, filename): |
| self._pcap_file = open('%s.pcap' % filename, 'wb') |
| self._pcap_file.write(self.encode_header()) |
| self._epoch = time.time() |
| |
| def encode_header(self): |
| """ Returns a pcap file header. """ |
| return struct.pack( |
| "<LHHLLLL", |
| PCAP_MAGIC_NUMBER, |
| PCAP_VERSION_MAJOR, |
| PCAP_VERSION_MINOR, |
| 0, |
| 0, |
| 256, |
| DLT_IEEE802_15_4, |
| ) |
| |
| def encode_frame(self, frame, sec, usec): |
| """ Returns a pcap encapsulation of the given frame. """ |
| frame = frame[1:] |
| length = len(frame) |
| pcap_frame = struct.pack("<LLLL", sec, usec, length, length) |
| pcap_frame += frame |
| return pcap_frame |
| |
| def _get_timestamp(self): |
| """ Returns the internal timestamp. """ |
| timestamp = time.time() - self._epoch |
| timestamp_sec = int(timestamp) |
| timestamp_usec = int((timestamp - timestamp_sec) * 1000000) |
| return timestamp_sec, timestamp_usec |
| |
| def append(self, frame, timestamp=None): |
| """ Appends a frame. """ |
| if timestamp is None: |
| timestamp = self._get_timestamp() |
| pkt = self.encode_frame(frame, *timestamp) |
| self._pcap_file.write(pkt) |
| self._pcap_file.flush() |
| |
| def __del__(self): |
| self._pcap_file.close() |