Package bounded X4 BLE diagnostics and USB mode reader
This commit is contained in:
DCCONSTRUCTIONS
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"""Read-only Options codec derived from the pinned SDK's descriptors/serializer.
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This establishes packet structure, not BLE support on a particular X4 firmware.
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No transport, pairing, setting changes, capture, reboot or generic send API.
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"""
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import struct
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MAX_PACKET = 4096
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READ_OPTIONS = frozenset({15, 48, 95, 97})
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def varint(value):
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if type(value) is not int or not 0 <= value < 2**64:
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raise ValueError("Invalid protobuf integer")
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result = bytearray()
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while value >= 128:
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result.append((value & 127) | 128)
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value >>= 7
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result.append(value)
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return bytes(result)
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def read_varint(data, offset):
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value = 0
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for shift in range(0, 70, 7):
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if offset >= len(data):
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raise ValueError("Truncated varint")
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byte = data[offset]
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offset += 1
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if shift == 63 and byte > 1:
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raise ValueError("Overflowed varint")
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value |= (byte & 127) << shift
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if not byte & 128:
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return value, offset
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raise ValueError("Oversized varint")
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def protobuf_fields(data):
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if len(data) > MAX_PACKET:
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raise ValueError("Oversized protobuf")
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result, offset = [], 0
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while offset < len(data):
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tag, offset = read_varint(data, offset)
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number, wire = tag >> 3, tag & 7
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if not 1 <= number <= 0x1FFFFFFF:
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raise ValueError("Invalid field number")
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if wire == 0:
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value, offset = read_varint(data, offset)
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elif wire in {1, 2, 5}:
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if wire == 2:
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size, offset = read_varint(data, offset)
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else:
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size = 8 if wire == 1 else 4
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if size > len(data) - offset:
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raise ValueError("Truncated field")
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value, offset = data[offset : offset + size], offset + size
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else:
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raise ValueError("Unsupported protobuf wire type")
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result.append((number, wire, value))
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return result
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def get_options_packet(options, message_id):
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if (
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not options
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or len(options) > 4
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or len(set(options)) != len(options)
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or any(type(x) is not int or x not in READ_OPTIONS for x in options)
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):
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raise ValueError("Only identity and USB/wakeup option reads are allowed")
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if type(message_id) is not int or not 1 <= message_id < 0x40000000:
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raise ValueError("Invalid message ID")
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payload = b"".join(b"\x08" + varint(option) for option in options)
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# CameraPacket header7 + CameraMessage header9. Command8=GET_OPTIONS.
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return (
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struct.pack("<IBHHBIH", 16 + len(payload), 4, 0, 8, 2, message_id | 0x80000000, 0) + payload
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)
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class PacketReader:
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"""Accept split/combined notifications; no unbounded resync or CRC guessing."""
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def __init__(self):
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self.buffer = bytearray()
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def feed(self, chunk):
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if not chunk or len(self.buffer) + len(chunk) > MAX_PACKET * 2:
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raise ValueError("Invalid notification size")
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self.buffer.extend(chunk)
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result = []
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while len(self.buffer) >= 4:
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size = struct.unpack_from("<I", self.buffer)[0]
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if not 16 <= size <= MAX_PACKET:
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raise ValueError("Unknown packet framing")
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if len(self.buffer) < size:
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break
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raw = bytes(self.buffer[:size])
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del self.buffer[:size]
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_, kind, reserved, code, content, ident, tail = struct.unpack("<IBHHBIH", raw[:16])
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if kind != 4 or reserved or tail or content != 2 or ident & 0xC0000000 != 0xC0000000:
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raise ValueError("Unsupported message header/direction/fragmentation")
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result.append(
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{"code": code, "message_id": ident & 0x3FFFFFFF, "payload": raw[16:], "raw": raw}
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)
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return result
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def decode_options_response(packet, message_id, requested):
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if packet["message_id"] != message_id:
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raise ValueError("Response belongs to another request")
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# HTTP-style response codes in the common protocol. Hardware must confirm.
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if packet["code"] != 200:
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raise ValueError("Camera did not return a successful response")
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listed, values = [], None
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for number, wire, value in protobuf_fields(packet["payload"]):
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if number == 1:
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if wire == 0:
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listed.append(value)
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elif wire == 2:
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offset = 0
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while offset < len(value):
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item, offset = read_varint(value, offset)
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listed.append(item)
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else:
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raise ValueError("Invalid option list")
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elif number == 2:
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if wire != 2 or values is not None:
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raise ValueError("Invalid or duplicate Options value")
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values = value
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if values is None or len(listed) != len(set(listed)) or not set(listed) <= set(requested):
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raise ValueError("Missing/ambiguous Options response")
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decoded = {}
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for number, wire, value in protobuf_fields(values):
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if number not in requested:
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continue
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if number in decoded or number not in listed:
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raise ValueError("Duplicate or unacknowledged option")
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if number in {15, 48}:
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if wire != 2 or not 1 <= len(value) <= 256:
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raise ValueError("Invalid camera identity")
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decoded[number] = value.decode("utf-8", errors="strict")
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else:
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if wire != 0 or value not in {0, 1}:
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raise ValueError("Unsupported option enum")
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decoded[number] = value
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# Missing scalar is unknown, NEVER default PC=0 or wakeup=0.
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return {
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number: {
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"acknowledged": number in listed,
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"present": number in decoded,
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"value": decoded.get(number),
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}
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for number in requested
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}
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