forked from auracaster/bumble_mirror
94 lines
3.0 KiB
Python
94 lines
3.0 KiB
Python
# Copyright 2021-2023 Google LLC
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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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# https://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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# Imports
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# -----------------------------------------------------------------------------
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from enum import IntEnum
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import struct
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import datetime
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from typing import BinaryIO
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from bumble.hci import HCI_Packet, HCI_COMMAND_PACKET, HCI_EVENT_PACKET
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# -----------------------------------------------------------------------------
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# Classes
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# -----------------------------------------------------------------------------
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class Snooper:
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"""
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Base class for snooper implementations.
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A snooper is an object that will be provided with HCI packets as they are
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exchanged between a host and a controller.
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"""
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class Direction(IntEnum):
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HOST_TO_CONTROLLER = 0
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CONTROLLER_TO_HOST = 1
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class DataLinkType(IntEnum):
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H1 = 1001
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H4 = 1002
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HCI_BSCP = 1003
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H5 = 1004
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def snoop(self, hci_packet: HCI_Packet, direction: Direction) -> None:
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"""Snoop on an HCI packet."""
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# -----------------------------------------------------------------------------
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class BtSnooper(Snooper):
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"""
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Snooper that saves HCI packets using the BTSnoop format, based on RFC 1761.
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"""
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IDENTIFICATION_PATTERN = b'btsnoop\0'
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TIMESTAMP_ANCHOR = datetime.datetime(2000, 1, 1)
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TIMESTAMP_DELTA = 0x00E03AB44A676000
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ONE_MS = datetime.timedelta(microseconds=1)
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def __init__(self, output: BinaryIO):
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self.output = output
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# Write the header
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self.output.write(
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self.IDENTIFICATION_PATTERN + struct.pack('>LL', 1, self.DataLinkType.H4)
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)
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def snoop(self, hci_packet: HCI_Packet, direction: Snooper.Direction) -> None:
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flags = int(direction)
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if hci_packet.hci_packet_type in (HCI_EVENT_PACKET, HCI_COMMAND_PACKET):
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flags |= 0x10
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# Compute the current timestamp
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timestamp = (
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int((datetime.datetime.utcnow() - self.TIMESTAMP_ANCHOR) / self.ONE_MS)
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+ self.TIMESTAMP_DELTA
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)
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# Emit the record
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packet_data = bytes(hci_packet)
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self.output.write(
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struct.pack(
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'>IIIIQ',
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len(packet_data), # Original Length
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len(packet_data), # Included Length
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flags, # Packet Flags
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0, # Cumulative Drops
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timestamp, # Timestamp
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)
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+ packet_data
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)
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