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Diffstat (limited to 'freestyle_hid/tools/extract_chatter.py')
| -rwxr-xr-x | freestyle_hid/tools/extract_chatter.py | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/freestyle_hid/tools/extract_chatter.py b/freestyle_hid/tools/extract_chatter.py new file mode 100755 index 0000000..a77a0ec --- /dev/null +++ b/freestyle_hid/tools/extract_chatter.py @@ -0,0 +1,233 @@ +#!/usr/bin/env python3 +# +# SPDX-FileCopyrightText: © 2019 The usbmon-tools Authors +# SPDX-FileCopyrightText: © 2020 The freestyle-hid Authors +# +# SPDX-License-Identifier: Apache-2.0 + +import logging +import sys +import textwrap +from typing import BinaryIO + +import click +import click_log +import construct +import usbmon +import usbmon.chatter +import usbmon.pcapng + +logger = logging.getLogger() +click_log.basic_config(logger) + +_KEEPALIVE_TYPE = 0x22 + +_UNENCRYPTED_TYPES = ( + 0x01, + 0x04, + 0x05, + 0x06, + 0x0C, + 0x0D, + 0x14, + 0x15, + 0x33, + 0x34, + 0x35, + 0x71, + _KEEPALIVE_TYPE, +) + +_ENCRYPTION_SETUP_TYPES = (0x14, 0x33) + +_START_AUTHORIZE_CMD = 0x11 +_CHALLENGE_CMD = 0x16 +_CHALLENGE_RESPONSE_CMD = 0x17 +_CHALLENGE_ACCEPTED_CMD = 0x18 + +_ABBOTT_VENDOR_ID = 0x1A61 +_LIBRE2_PRODUCT_ID = 0x3950 + +_ENCRYPTED_MESSAGE = construct.Struct( + message_type=construct.Byte, + encrypted_message=construct.Bytes(64 - 1 - 4 - 4), + sequence_number=construct.Int32ul, + mac=construct.Int32ul, +) + + +@click.command() +@click_log.simple_verbosity_option(logger, "--vlog") +@click.option( + "--device-address", + help=( + "Device address (busnum.devnum) of the device to extract capture" + " of. If none provided, device descriptors will be relied on." + ), +) +@click.option( + "--encrypted-protocol / --no-encrypted-protocol", + default=False, + help=( + "Whether to expect encrypted protocol in the capture." + " Ignored if the device descriptors are present in the capture." + ), +) +@click.option( + "--verbose-encryption-setup / --no-verbose-encryption-setup", + default=False, + help=( + "Whether to parse encryption setup commands and printing their component" + " together with the raw messsage." + ), +) +@click.option( + "--print-keepalive / --no-print-keepalive", + default=False, + help=( + "Whether to print the keepalive messages sent by the device. " + "Keepalive messages are usually safely ignored." + ), +) +@click.argument( + "pcap-file", + type=click.File(mode="rb"), +) +def main( + *, + device_address: str, + encrypted_protocol: bool, + verbose_encryption_setup: bool, + print_keepalive: bool, + pcap_file: BinaryIO, +) -> None: + if sys.version_info < (3, 7): + raise Exception("Unsupported Python version, please use at least Python 3.7.") + + session = usbmon.pcapng.parse_stream(pcap_file, retag_urbs=False) + + if not device_address: + for descriptor in session.device_descriptors.values(): + if descriptor.vendor_id == _ABBOTT_VENDOR_ID: + if device_address and device_address != descriptor.address: + raise Exception( + "Multiple Abbott device present in capture, please" + " provide a --device-address flag." + ) + device_address = descriptor.address + + if device_address not in session.device_descriptors: + logging.warning( + f"Unable to find device {device_address} in the capture's descriptors." + " Assuming non-encrypted protocol.", + ) + else: + descriptor = session.device_descriptors[device_address] + assert descriptor.vendor_id == _ABBOTT_VENDOR_ID + + if descriptor.product_id == _LIBRE2_PRODUCT_ID: + encrypted_protocol = True + + for first, second in session.in_pairs(): + # Ignore stray callbacks/errors. + if not first.type == usbmon.constants.PacketType.SUBMISSION: + continue + + if not first.address.startswith(f"{device_address}."): + # No need to check second, they will be linked. + continue + + if first.xfer_type == usbmon.constants.XferType.INTERRUPT: + pass + elif ( + first.xfer_type == usbmon.constants.XferType.CONTROL + and not first.setup_packet + or first.setup_packet.type == usbmon.setup.Type.CLASS # type: ignore + ): + pass + else: + continue + + if first.direction == usbmon.constants.Direction.OUT: + packet = first + else: + assert second is not None + packet = second + + if not packet.payload: + continue + + assert len(packet.payload) >= 2 + + message_type = packet.payload[0] + + if message_type == _KEEPALIVE_TYPE and not print_keepalive: + continue + + message_metadata = [] + + if encrypted_protocol and message_type not in _UNENCRYPTED_TYPES: + # With encrypted communication, the length of the message is also encrypted, + # and all the packets use the full 64 bytes. So instead, we extract what + # metadata we can. + parsed = _ENCRYPTED_MESSAGE.parse(packet.payload) + message_metadata.extend( + [f"SEQUENCE_NUMBER={parsed.sequence_number}", f"MAC={parsed.mac:04x}"] + ) + + message_type_str = f"x{message_type:02x}" + message = parsed.encrypted_message + elif verbose_encryption_setup and message_type in _ENCRYPTION_SETUP_TYPES: + message_length = packet.payload[1] + message_end_idx = 2 + message_length + message = packet.payload[2:message_end_idx] + + if message[0] == _START_AUTHORIZE_CMD: + message_metadata.append("START_AUTHORIZE") + elif message[0] == _CHALLENGE_CMD: + message_metadata.append("CHALLENGE") + challenge = message[1:9] + iv = message[9:16] + message_metadata.append(f"CHALLENGE={challenge.hex()}") + message_metadata.append(f"IV={iv.hex()}") + elif message[0] == _CHALLENGE_RESPONSE_CMD: + message_metadata.append("CHALLENGE_RESPONSE") + encrypted_challenge = message[1:17] + challenge_mac = message[18:26] + message_metadata.append( + f"ENCRYPTED_CHALLENGE={encrypted_challenge.hex()}" + ) + message_metadata.append(f"MAC={challenge_mac.hex()}") + elif message[0] == _CHALLENGE_ACCEPTED_CMD: + message_metadata.append("CHALLENGE_ACCEPTED") + + message_metadata.append(f"RAW_LENGTH={message_length}") + message_type_str = f" {message_type:02x}" + else: + message_length = packet.payload[1] + message_metadata.append(f"LENGTH={message_length}") + message_end_idx = 2 + message_length + message_type_str = f" {message_type:02x}" + message = packet.payload[2:message_end_idx] + + if message_metadata: + metadata_string = "\n".join( + textwrap.wrap( + " ".join(message_metadata), width=80, break_long_words=False + ) + ) + print(metadata_string) + + print( + usbmon.chatter.dump_bytes( + packet.direction, + message, + prefix=f"[{message_type_str}]", + print_empty=True, + ), + "\n", + ) + + +if __name__ == "__main__": + main() |