bluezdbus: Add BLEAK_DBUS_UID override

CHANGELOG.rst

@@ -12,6 +12,7 @@ and this project adheres to `Semantic Versioning <https://semver.org/spec/v2.0.0
 
 Added
 -----
+* Added DBUS UID override for BlueZ
 * Added return type None to some scanner methods.
 * Added optional hack to use Bluetooth address instead of UUID on macOS.
 * Added ``BleakScanner.find_device_by_name()`` class method.

bleak/backends/bluezdbus/client.py

@@ -30,7 +30,7 @@
 from .characteristic import BleakGATTCharacteristicBlueZDBus
 from .manager import get_global_bluez_manager
 from .scanner import BleakScannerBlueZDBus
-from .utils import assert_reply
+from .utils import assert_reply, get_dbus_authenticator
 from .version import BlueZFeatures
 
 logger = logging.getLogger(__name__)
@@ -130,7 +130,7 @@ async def connect(self, dangerous_use_bleak_cache: bool = False, **kwargs) -> bo
         # Each BLE connection session needs a new D-Bus connection to avoid a
         # BlueZ quirk where notifications are automatically enabled on reconnect.
         self._bus = await MessageBus(
-            bus_type=BusType.SYSTEM, negotiate_unix_fd=True
+            bus_type=BusType.SYSTEM, negotiate_unix_fd=True, auth=get_dbus_authenticator()
         ).connect()
 
         def on_connected_changed(connected: bool) -> None:

bleak/backends/bluezdbus/manager.py

@@ -36,7 +36,7 @@
 from .descriptor import BleakGATTDescriptorBlueZDBus
 from .service import BleakGATTServiceBlueZDBus
 from .signals import MatchRules, add_match
-from .utils import assert_reply
+from .utils import assert_reply, get_dbus_authenticator
 
 logger = logging.getLogger(__name__)
 
@@ -187,7 +187,7 @@ async def async_init(self):
             # We need to create a new MessageBus each time as
             # dbus-next will destory the underlying file descriptors
             # when the previous one is closed in its finalizer.
-            bus = MessageBus(bus_type=BusType.SYSTEM)
+            bus = MessageBus(bus_type=BusType.SYSTEM, auth=get_dbus_authenticator())
             await bus.connect()
 
             try:

bleak/backends/bluezdbus/utils.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 import re
 
+from dbus_fast.auth import AuthExternal
 from dbus_fast.constants import MessageType
 from dbus_fast.message import Message
 
@@ -43,3 +44,14 @@ def bdaddr_from_device_path(device_path: str) -> str:
         A Bluetooth address as a string.
     """
     return ":".join(device_path[-17:].split("_"))
+
+
+def get_dbus_authenticator():
+    uid = 0
+    try:
+        uid = int(os.environ("BLEAK_DBUS_UID"))
+    except ValueError as e:
+        pass
+    auth = None
+    if uid:
+        auth = AuthExternal(uid=uid)

docs/backends/linux.rst

@@ -41,6 +41,12 @@ individual Bleak objects should not be shared between event loops. Otherwise,
 RuntimeErrors similar to ``[...] got Future <Future pending> attached to a
 different loop`` will be thrown.
 
+User Namespaces
+---------------
+
+DBus authentication will fail if the client is invoked from within a user namespace.
+To work around this, use the `BLEAK_DBUS_UID` environment variable to hardcode a UID.
+
 API
 ---