scanner: detect OF devices in Nearby state

examples/device_scanner.py

@@ -1,11 +1,36 @@
 import asyncio
 import logging
 
-from findmy.scanner import OfflineFindingScanner
+from findmy.scanner import (
+    NearbyOfflineFindingDevice,
+    OfflineFindingScanner,
+    SeparatedOfflineFindingDevice,
+)
 
 logging.basicConfig(level=logging.INFO)
 
 
+def _print_nearby(device: NearbyOfflineFindingDevice) -> None:
+    print(f"NEARBY Device - {device.mac_address}")
+    print(f"  Status byte:  {device.status:x}")
+    print("  Extra data:")
+    for k, v in sorted(device.additional_data.items()):
+        print(f"    {k:20}: {v}")
+    print()
+
+
+def _print_separated(device: SeparatedOfflineFindingDevice) -> None:
+    print(f"SEPARATED Device - {device.mac_address}")
+    print(f"  Public key:   {device.adv_key_b64}")
+    print(f"  Lookup key:   {device.hashed_adv_key_b64}")
+    print(f"  Status byte:  {device.status:x}")
+    print(f"  Hint byte:    {device.hint:x}")
+    print("  Extra data:")
+    for k, v in sorted(device.additional_data.items()):
+        print(f"    {k:20}: {v}")
+    print()
+
+
 async def scan() -> None:
     scanner = await OfflineFindingScanner.create()
 
@@ -13,15 +38,13 @@ async def scan() -> None:
     print()
 
     async for device in scanner.scan_for(10, extend_timeout=True):
-        print(f"Device - {device.mac_address}")
-        print(f"  Public key:   {device.adv_key_b64}")
-        print(f"  Lookup key:   {device.hashed_adv_key_b64}")
-        print(f"  Status byte:  {device.status:x}")
-        print(f"  Hint byte:    {device.hint:x}")
-        print("  Extra data:")
-        for k, v in sorted(device.additional_data.items()):
-            print(f"    {k:20}: {v}")
-        print()
+        if isinstance(device, NearbyOfflineFindingDevice):
+            _print_nearby(device)
+        elif isinstance(device, SeparatedOfflineFindingDevice):
+            _print_separated(device)
+        else:
+            print(f"Unknown device: {device}")
+            print()
 
 
 if __name__ == "__main__":

findmy/scanner/__init__.py

@@ -1,4 +1,12 @@
 """Utilities related to physically discoverable FindMy-devices."""
-from .scanner import OfflineFindingScanner
+from .scanner import (
+    NearbyOfflineFindingDevice,
+    OfflineFindingScanner,
+    SeparatedOfflineFindingDevice,
+)
 
-__all__ = ("OfflineFindingScanner",)
+__all__ = (
+    "OfflineFindingScanner",
+    "NearbyOfflineFindingDevice",
+    "SeparatedOfflineFindingDevice",
+)

findmy/scanner/scanner.py

@@ -1,9 +1,11 @@
 """Airtag scanner."""
+
 from __future__ import annotations
 
 import asyncio
 import logging
 import time
+from abc import ABC, abstractmethod
 from typing import TYPE_CHECKING, Any, AsyncGenerator
 
 from bleak import BleakScanner
@@ -18,12 +20,151 @@ if TYPE_CHECKING:
 logging.getLogger(__name__)
 
 
-class OfflineFindingDevice(HasPublicKey):
+class OfflineFindingDevice(ABC):
     """Device discoverable through Apple's bluetooth-based Offline Finding protocol."""
 
     OF_HEADER_SIZE = 2
     OF_TYPE = 0x12
-    OF_DATA_LEN = 25
+
+    @classmethod
+    @property
+    @abstractmethod
+    def payload_len(cls) -> int:
+        """Length of OfflineFinding data payload in bytes."""
+        raise NotImplementedError
+
+    def __init__(
+        self,
+        mac_bytes: bytes,
+        additional_data: dict[Any, Any] | None = None,
+    ) -> None:
+        """Instantiate an OfflineFindingDevice."""
+        self._mac_bytes: bytes = mac_bytes
+        self._additional_data: dict[Any, Any] = additional_data or {}
+
+    @property
+    def mac_address(self) -> str:
+        """MAC address of the device in AA:BB:CC:DD:EE:FF format."""
+        mac = self._mac_bytes.hex().upper()
+        return ":".join(mac[i : i + 2] for i in range(0, len(mac), 2))
+
+    @property
+    def additional_data(self) -> dict[Any, Any]:
+        """Any additional data. No guarantees about the contents of this dictionary."""
+        return self._additional_data
+
+    @classmethod
+    @abstractmethod
+    def from_payload(
+        cls,
+        mac_address: str,
+        payload: bytes,
+        additional_data: dict[Any, Any] | None,
+    ) -> OfflineFindingDevice | None:
+        """Get a NearbyOfflineFindingDevice object from an OF message payload."""
+        raise NotImplementedError
+
+    @classmethod
+    def from_ble_payload(
+        cls,
+        mac_address: str,
+        ble_payload: bytes,
+        additional_data: dict[Any, Any] | None = None,
+    ) -> OfflineFindingDevice | None:
+        """Get a NearbyOfflineFindingDevice object from a BLE packet payload."""
+        if len(ble_payload) < cls.OF_HEADER_SIZE:
+            logging.error("Not enough bytes to decode: %s", len(ble_payload))
+            return None
+        if ble_payload[0] != cls.OF_TYPE:
+            logging.debug("Unsupported OF type: %s", ble_payload[0])
+            return None
+
+        device_type = next(
+            (dev for dev in cls.__subclasses__() if dev.payload_len == ble_payload[1]),
+            None,
+        )
+        if device_type is None:
+            logging.error("Invalid OF payload length: %s", ble_payload[1])
+            return None
+
+        return device_type.from_payload(
+            mac_address,
+            ble_payload[cls.OF_HEADER_SIZE :],
+            additional_data,
+        )
+
+    @override
+    def __eq__(self, other: object) -> bool:
+        if isinstance(other, OfflineFindingDevice):
+            return self.mac_address == other.mac_address
+
+        return NotImplemented
+
+    @override
+    def __hash__(self) -> int:
+        return int.from_bytes(self._mac_bytes)
+
+
+class NearbyOfflineFindingDevice(OfflineFindingDevice):
+    """Offline-Finding device in nearby state."""
+
+    @classmethod
+    @property
+    @override
+    def payload_len(cls) -> int:
+        """Length of OfflineFinding data payload in bytes."""
+        return 0x02  # 2
+
+    def __init__(
+        self,
+        mac_bytes: bytes,
+        status_byte: int,
+        extra_byte: int,
+        additional_data: dict[Any, Any] | None = None,
+    ) -> None:
+        """Instantiate a NearbyOfflineFindingDevice."""
+        super().__init__(mac_bytes, additional_data)
+
+        self._status_byte: int = status_byte
+        self._extra_byte: int = extra_byte
+
+    @property
+    def status(self) -> int:
+        """Status value as reported by the device."""
+        return self._status_byte % 255
+
+    @classmethod
+    @override
+    def from_payload(
+        cls,
+        mac_address: str,
+        payload: bytes,
+        additional_data: dict[Any, Any] | None = None,
+    ) -> NearbyOfflineFindingDevice | None:
+        """Get a NearbyOfflineFindingDevice object from an OF message payload."""
+        if len(payload) != cls.payload_len:
+            logging.error(
+                "Invalid OF data length: %s instead of %s",
+                len(payload),
+                payload[1],
+            )
+
+        mac_bytes = bytes.fromhex(mac_address.replace(":", "").replace("-", ""))
+        status_byte = payload[0]
+        extra_byte = payload[1]
+
+        return NearbyOfflineFindingDevice(mac_bytes, status_byte, extra_byte, additional_data)
+
+
+class SeparatedOfflineFindingDevice(OfflineFindingDevice, HasPublicKey):
+    """Offline-Finding device in separated state."""
+
+    @classmethod
+    @property
+    @override
+    def payload_len(cls) -> int:
+        """Length of OfflineFinding data in bytes."""
+        return 0x19  # 25
 
     def __init__(  # noqa: PLR0913
         self,
@@ -33,20 +174,13 @@ class OfflineFindingDevice(HasPublicKey):
         hint: int,
         additional_data: dict[Any, Any] | None = None,
     ) -> None:
-        """Initialize an `OfflineFindingDevice`."""
-        self._mac_bytes: bytes = mac_bytes
+        """Initialize a `SeparatedOfflineFindingDevice`."""
+        super().__init__(mac_bytes, additional_data)
+
         self._status: int = status
         self._public_key: bytes = public_key
         self._hint: int = hint
 
-        self._additional_data: dict[Any, Any] = additional_data or {}
-
-    @property
-    def mac_address(self) -> str:
-        """MAC address of the device in AA:BB:CC:DD:EE:FF format."""
-        mac = self._mac_bytes.hex().upper()
-        return ":".join(mac[i : i + 2] for i in range(0, len(mac), 2))
-
     @property
     def status(self) -> int:
         """Status value as reported by the device."""
@@ -57,11 +191,6 @@ class OfflineFindingDevice(HasPublicKey):
         """Hint value as reported by the device."""
         return self._hint % 255
 
-    @property
-    def additional_data(self) -> dict[Any, Any]:
-        """Any additional data. No guarantees about the contents of this dictionary."""
-        return self._additional_data
-
     @property
     @override
     def adv_key_bytes(self) -> bytes:
@@ -69,44 +198,36 @@ class OfflineFindingDevice(HasPublicKey):
         return self._public_key
 
     @classmethod
+    @override
     def from_payload(
         cls,
         mac_address: str,
         payload: bytes,
-        additional_data: dict[Any, Any],
-    ) -> OfflineFindingDevice | None:
-        """Get an OfflineFindingDevice object from a BLE payload."""
-        if len(payload) < cls.OF_HEADER_SIZE:
-            logging.error("Not enough bytes to decode: %s", len(payload))
-            return None
-        if payload[0] != cls.OF_TYPE:
-            logging.debug("Unsupported OF type: %s", payload[0])
-            return None
-        if payload[1] != cls.OF_DATA_LEN:
-            logging.debug("Unknown OF data length: %s", payload[1])
-            return None
-        if len(payload) != cls.OF_HEADER_SIZE + cls.OF_DATA_LEN:
-            logging.debug(
+        additional_data: dict[Any, Any] | None = None,
+    ) -> SeparatedOfflineFindingDevice | None:
+        """Get a SeparatedOfflineFindingDevice object from an OF message payload."""
+        if len(payload) != cls.payload_len:
+            logging.error(
                 "Invalid OF data length: %s instead of %s",
-                len(payload) - cls.OF_HEADER_SIZE,
+                len(payload),
                 payload[1],
             )
             return None
 
         mac_bytes = bytes.fromhex(mac_address.replace(":", "").replace("-", ""))
 
-        status = payload[cls.OF_HEADER_SIZE + 0]
+        status = payload[0]
 
-        pubkey_end = payload[cls.OF_HEADER_SIZE + 1 : cls.OF_HEADER_SIZE + 23]
+        pubkey_end = payload[1:23]
         pubkey_middle = mac_bytes[1:]
-        pubkey_start_ms = payload[cls.OF_HEADER_SIZE + 23] << 6
+        pubkey_start_ms = payload[23] << 6
         pubkey_start_ls = mac_bytes[0] & 0b00111111
         pubkey_start = (pubkey_start_ms | pubkey_start_ls).to_bytes(1, "big")
         pubkey = pubkey_start + pubkey_middle + pubkey_end
 
-        hint = payload[cls.OF_HEADER_SIZE + 24]
+        hint = payload[24]
 
-        return OfflineFindingDevice(mac_bytes, status, pubkey, hint, additional_data)
+        return SeparatedOfflineFindingDevice(mac_bytes, status, pubkey, hint, additional_data)
 
     @override
     def __repr__(self) -> str:
@@ -179,7 +300,7 @@ class OfflineFindingScanner:
             # Likely Windows host, where details is a '_RawAdvData' object.
             # See: https://github.com/malmeloo/FindMy.py/issues/24
             additional_data = {}
-        return OfflineFindingDevice.from_payload(device.address, apple_data, additional_data)
+        return OfflineFindingDevice.from_ble_payload(device.address, apple_data, additional_data)
 
     async def scan_for(
         self,