forked from auracaster/bumble_mirror
Support GATT Service
This commit is contained in:
Josh Wu
166
bumble/profiles/gatt_service.py
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166
bumble/profiles/gatt_service.py
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# Copyright 2021-2025 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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from __future__ import annotations
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import struct
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from typing import TYPE_CHECKING
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from bumble import att
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from bumble import gatt
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from bumble import gatt_client
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from bumble import crypto
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if TYPE_CHECKING:
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from bumble import device
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# -----------------------------------------------------------------------------
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class GenericAttributeProfileService(gatt.TemplateService):
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'''See Vol 3, Part G - 7 - DEFINED GENERIC ATTRIBUTE PROFILE SERVICE.'''
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UUID = gatt.GATT_GENERIC_ATTRIBUTE_SERVICE
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client_supported_features_characteristic: gatt.Characteristic | None = None
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server_supported_features_characteristic: gatt.Characteristic | None = None
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database_hash_characteristic: gatt.Characteristic | None = None
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service_changed_characteristic: gatt.Characteristic | None = None
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def __init__(
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self,
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server_supported_features: gatt.ServerSupportedFeatures | None = None,
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database_hash_enabled: bool = True,
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service_change_enabled: bool = True,
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) -> None:
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if server_supported_features is not None:
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self.server_supported_features_characteristic = gatt.Characteristic(
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uuid=gatt.GATT_SERVER_SUPPORTED_FEATURES_CHARACTERISTIC,
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properties=gatt.Characteristic.Properties.READ,
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permissions=gatt.Characteristic.Permissions.READABLE,
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value=bytes([server_supported_features]),
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)
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if database_hash_enabled:
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self.database_hash_characteristic = gatt.Characteristic(
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uuid=gatt.GATT_DATABASE_HASH_CHARACTERISTIC,
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properties=gatt.Characteristic.Properties.READ,
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permissions=gatt.Characteristic.Permissions.READABLE,
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value=gatt.CharacteristicValue(read=self.get_database_hash),
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)
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if service_change_enabled:
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self.service_changed_characteristic = gatt.Characteristic(
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uuid=gatt.GATT_SERVICE_CHANGED_CHARACTERISTIC,
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properties=gatt.Characteristic.Properties.INDICATE,
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permissions=gatt.Characteristic.Permissions(0),
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value=b'',
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)
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if (database_hash_enabled and service_change_enabled) or (
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server_supported_features
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and (
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server_supported_features & gatt.ServerSupportedFeatures.EATT_SUPPORTED
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)
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): # TODO: Support Multiple Handle Value Notifications
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self.client_supported_features_characteristic = gatt.Characteristic(
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uuid=gatt.GATT_CLIENT_SUPPORTED_FEATURES_CHARACTERISTIC,
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properties=(
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gatt.Characteristic.Properties.READ
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| gatt.Characteristic.Properties.WRITE
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),
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permissions=(
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gatt.Characteristic.Permissions.READABLE
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| gatt.Characteristic.Permissions.WRITEABLE
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),
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value=bytes(1),
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)
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super().__init__(
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characteristics=[
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c
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for c in (
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self.service_changed_characteristic,
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self.client_supported_features_characteristic,
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self.database_hash_characteristic,
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self.server_supported_features_characteristic,
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)
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if c is not None
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],
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primary=True,
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)
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@classmethod
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def get_attribute_data(cls, attribute: att.Attribute) -> bytes:
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if attribute.type in (
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gatt.GATT_PRIMARY_SERVICE_ATTRIBUTE_TYPE,
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gatt.GATT_SECONDARY_SERVICE_ATTRIBUTE_TYPE,
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gatt.GATT_INCLUDE_ATTRIBUTE_TYPE,
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gatt.GATT_CHARACTERISTIC_ATTRIBUTE_TYPE,
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gatt.GATT_CHARACTERISTIC_EXTENDED_PROPERTIES_DESCRIPTOR,
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):
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return (
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struct.pack("<H", attribute.handle)
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+ attribute.type.to_bytes()
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+ attribute.value
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)
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elif attribute.type in (
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gatt.GATT_CHARACTERISTIC_USER_DESCRIPTION_DESCRIPTOR,
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gatt.GATT_CLIENT_CHARACTERISTIC_CONFIGURATION_DESCRIPTOR,
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gatt.GATT_SERVER_CHARACTERISTIC_CONFIGURATION_DESCRIPTOR,
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gatt.GATT_CHARACTERISTIC_PRESENTATION_FORMAT_DESCRIPTOR,
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gatt.GATT_CHARACTERISTIC_AGGREGATE_FORMAT_DESCRIPTOR,
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):
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return struct.pack("<H", attribute.handle) + attribute.type.to_bytes()
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return b''
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def get_database_hash(self, connection: device.Connection | None) -> bytes:
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assert connection
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m = b''.join(
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[
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self.get_attribute_data(attribute)
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for attribute in connection.device.gatt_server.attributes
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]
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)
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return crypto.aes_cmac(m=m, k=bytes(16))
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class GenericAttributeProfileServiceProxy(gatt_client.ProfileServiceProxy):
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SERVICE_CLASS = GenericAttributeProfileService
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client_supported_features_characteristic: gatt_client.CharacteristicProxy | None = (
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None
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)
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server_supported_features_characteristic: gatt_client.CharacteristicProxy | None = (
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None
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)
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database_hash_characteristic: gatt_client.CharacteristicProxy | None = None
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service_changed_characteristic: gatt_client.CharacteristicProxy | None = None
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_CHARACTERISTICS = {
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gatt.GATT_CLIENT_SUPPORTED_FEATURES_CHARACTERISTIC: 'client_supported_features_characteristic',
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gatt.GATT_SERVER_SUPPORTED_FEATURES_CHARACTERISTIC: 'server_supported_features_characteristic',
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gatt.GATT_DATABASE_HASH_CHARACTERISTIC: 'database_hash_characteristic',
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gatt.GATT_SERVICE_CHANGED_CHARACTERISTIC: 'service_changed_characteristic',
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}
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def __init__(self, service_proxy: gatt_client.ServiceProxy) -> None:
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self.service_proxy = service_proxy
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for uuid, attribute_name in self._CHARACTERISTICS.items():
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if characteristics := self.service_proxy.get_characteristics_by_uuid(uuid):
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setattr(self, attribute_name, characteristics[0])
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