Add Volume Offset Control Service

bumble/profiles/vocs.py

@@ -0,0 +1,330 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+import struct
+from dataclasses import dataclass
+from typing import Optional
+
+from bumble.device import Connection
+from bumble.att import ATT_Error
+from bumble.gatt import (
+    Characteristic,
+    DelegatedCharacteristicAdapter,
+    TemplateService,
+    CharacteristicValue,
+    UTF8CharacteristicAdapter,
+    InvalidServiceError,
+    GATT_VOLUME_OFFSET_CONTROL_SERVICE,
+    GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC,
+    GATT_AUDIO_LOCATION_CHARACTERISTIC,
+    GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC,
+    GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC,
+)
+from bumble.gatt_client import ProfileServiceProxy, ServiceProxy
+from bumble.utils import OpenIntEnum
+from bumble.profiles.bap import AudioLocation
+
+# -----------------------------------------------------------------------------
+# Constants
+# -----------------------------------------------------------------------------
+
+MIN_VOLUME_OFFSET = -255
+MAX_VOLUME_OFFSET = 255
+CHANGE_COUNTER_MAX_VALUE = 0xFF
+
+
+class SetVolumeOffsetOpCode(OpenIntEnum):
+    SET_VOLUME_OFFSET = 0x01
+
+
+class ErrorCode(OpenIntEnum):
+    """
+    See Volume Offset Control Service 1.6. Application error codes.
+    """
+
+    INVALID_CHANGE_COUNTER = 0x80
+    OPCODE_NOT_SUPPORTED = 0x81
+    VALUE_OUT_OF_RANGE = 0x82
+
+
+# -----------------------------------------------------------------------------
+@dataclass
+class VolumeOffsetState:
+    volume_offset: int = 0
+    change_counter: int = 0
+    attribute_value: Optional[CharacteristicValue] = None
+
+    def __bytes__(self) -> bytes:
+        return struct.pack('<hB', self.volume_offset, self.change_counter)
+
+    @classmethod
+    def from_bytes(cls, data: bytes):
+        volume_offset, change_counter = struct.unpack('<hB', data)
+        return cls(volume_offset, change_counter)
+
+    def increment_change_counter(self) -> None:
+        self.change_counter = (self.change_counter + 1) % (CHANGE_COUNTER_MAX_VALUE + 1)
+
+    async def notify_subscribers_via_connection(self, connection: Connection) -> None:
+        assert self.attribute_value is not None
+        await connection.device.notify_subscribers(
+            attribute=self.attribute_value, value=bytes(self)
+        )
+
+    def on_read(self, _connection: Optional[Connection]) -> bytes:
+        return bytes(self)
+
+
+@dataclass
+class VocsAudioLocation:
+    audio_location: AudioLocation = AudioLocation.NOT_ALLOWED
+    attribute_value: Optional[CharacteristicValue] = None
+
+    def __bytes__(self) -> bytes:
+        return struct.pack('<I', self.audio_location)
+
+    @classmethod
+    def from_bytes(cls, data: bytes):
+        audio_location = AudioLocation(struct.unpack('<I', data)[0])
+        return cls(audio_location)
+
+    def on_read(self, _connection: Optional[Connection]) -> bytes:
+        return bytes(self)
+
+    async def on_write(self, connection: Optional[Connection], value: bytes) -> None:
+        assert connection
+        assert self.attribute_value
+
+        self.audio_location = AudioLocation(int.from_bytes(value, 'little'))
+        await connection.device.notify_subscribers(
+            attribute=self.attribute_value, value=value
+        )
+
+
+@dataclass
+class VolumeOffsetControlPoint:
+    volume_offset_state: VolumeOffsetState
+
+    async def on_write(self, connection: Optional[Connection], value: bytes) -> None:
+        assert connection
+
+        opcode = value[0]
+        if opcode != SetVolumeOffsetOpCode.SET_VOLUME_OFFSET:
+            raise ATT_Error(ErrorCode.OPCODE_NOT_SUPPORTED)
+
+        change_counter, volume_offset = struct.unpack('<Bh', value[1:])
+        await self._set_volume_offset(connection, change_counter, volume_offset)
+
+    async def _set_volume_offset(
+        self,
+        connection: Connection,
+        change_counter_operand: int,
+        volume_offset_operand: int,
+    ) -> None:
+        change_counter = self.volume_offset_state.change_counter
+
+        if change_counter != change_counter_operand:
+            raise ATT_Error(ErrorCode.INVALID_CHANGE_COUNTER)
+
+        if not MIN_VOLUME_OFFSET <= volume_offset_operand <= MAX_VOLUME_OFFSET:
+            raise ATT_Error(ErrorCode.VALUE_OUT_OF_RANGE)
+
+        self.volume_offset_state.volume_offset = volume_offset_operand
+        self.volume_offset_state.increment_change_counter()
+        await self.volume_offset_state.notify_subscribers_via_connection(connection)
+
+
+@dataclass
+class AudioOutputDescription:
+    audio_output_description: str = ''
+    attribute_value: Optional[CharacteristicValue] = None
+
+    @classmethod
+    def from_bytes(cls, data: bytes):
+        return cls(audio_output_description=data.decode('utf-8'))
+
+    def __bytes__(self) -> bytes:
+        return self.audio_output_description.encode('utf-8')
+
+    def on_read(self, _connection: Optional[Connection]) -> bytes:
+        return bytes(self)
+
+    async def on_write(self, connection: Optional[Connection], value: bytes) -> None:
+        assert connection
+        assert self.attribute_value
+
+        self.audio_output_description = value.decode('utf-8')
+        await connection.device.notify_subscribers(
+            attribute=self.attribute_value, value=value
+        )
+
+
+# -----------------------------------------------------------------------------
+class VolumeOffsetControlService(TemplateService):
+    UUID = GATT_VOLUME_OFFSET_CONTROL_SERVICE
+
+    def __init__(
+        self,
+        volume_offset_state: Optional[VolumeOffsetState] = None,
+        audio_location: Optional[VocsAudioLocation] = None,
+        audio_output_description: Optional[AudioOutputDescription] = None,
+    ) -> None:
+
+        self.volume_offset_state = (
+            VolumeOffsetState() if volume_offset_state is None else volume_offset_state
+        )
+
+        self.audio_location = (
+            VocsAudioLocation() if audio_location is None else audio_location
+        )
+
+        self.audio_output_description = (
+            AudioOutputDescription()
+            if audio_output_description is None
+            else audio_output_description
+        )
+
+        self.volume_offset_control_point: VolumeOffsetControlPoint = (
+            VolumeOffsetControlPoint(self.volume_offset_state)
+        )
+
+        self.volume_offset_state_characteristic = DelegatedCharacteristicAdapter(
+            Characteristic(
+                uuid=GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC,
+                properties=(
+                    Characteristic.Properties.READ | Characteristic.Properties.NOTIFY
+                ),
+                permissions=Characteristic.Permissions.READ_REQUIRES_ENCRYPTION,
+                value=CharacteristicValue(read=self.volume_offset_state.on_read),
+            ),
+            encode=lambda value: bytes(value),
+        )
+
+        self.audio_location_characteristic = DelegatedCharacteristicAdapter(
+            Characteristic(
+                uuid=GATT_AUDIO_LOCATION_CHARACTERISTIC,
+                properties=(
+                    Characteristic.Properties.READ
+                    | Characteristic.Properties.NOTIFY
+                    | Characteristic.Properties.WRITE_WITHOUT_RESPONSE
+                ),
+                permissions=(
+                    Characteristic.Permissions.READ_REQUIRES_ENCRYPTION
+                    | Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION
+                ),
+                value=CharacteristicValue(
+                    read=self.audio_location.on_read,
+                    write=self.audio_location.on_write,
+                ),
+            ),
+            encode=lambda value: bytes(value),
+            decode=VocsAudioLocation.from_bytes,
+        )
+        self.audio_location.attribute_value = self.audio_location_characteristic.value
+
+        self.volume_offset_control_point_characteristic = Characteristic(
+            uuid=GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC,
+            properties=Characteristic.Properties.WRITE,
+            permissions=Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION,
+            value=CharacteristicValue(write=self.volume_offset_control_point.on_write),
+        )
+
+        self.audio_output_description_characteristic = DelegatedCharacteristicAdapter(
+            Characteristic(
+                uuid=GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC,
+                properties=(
+                    Characteristic.Properties.READ
+                    | Characteristic.Properties.NOTIFY
+                    | Characteristic.Properties.WRITE_WITHOUT_RESPONSE
+                ),
+                permissions=(
+                    Characteristic.Permissions.READ_REQUIRES_ENCRYPTION
+                    | Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION
+                ),
+                value=CharacteristicValue(
+                    read=self.audio_output_description.on_read,
+                    write=self.audio_output_description.on_write,
+                ),
+            )
+        )
+
+        self.audio_output_description.attribute_value = (
+            self.audio_output_description_characteristic.value
+        )
+
+        super().__init__(
+            characteristics=[
+                self.volume_offset_state_characteristic,  # type: ignore
+                self.audio_location_characteristic,  # type: ignore
+                self.volume_offset_control_point_characteristic,  # type: ignore
+                self.audio_output_description_characteristic,  # type: ignore
+            ],
+            primary=False,
+        )
+
+
+# -----------------------------------------------------------------------------
+# Client
+# -----------------------------------------------------------------------------
+class VolumeOffsetControlServiceProxy(ProfileServiceProxy):
+    SERVICE_CLASS = VolumeOffsetControlService
+
+    def __init__(self, service_proxy: ServiceProxy) -> None:
+        self.service_proxy = service_proxy
+
+        if not (
+            characteristics := service_proxy.get_characteristics_by_uuid(
+                GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC
+            )
+        ):
+            raise InvalidServiceError("Volume Offset State characteristic not found")
+        self.volume_offset_state = DelegatedCharacteristicAdapter(
+            characteristics[0], decode=VolumeOffsetState.from_bytes
+        )
+
+        if not (
+            characteristics := service_proxy.get_characteristics_by_uuid(
+                GATT_AUDIO_LOCATION_CHARACTERISTIC
+            )
+        ):
+            raise InvalidServiceError("Audio Location characteristic not found")
+        self.audio_location = DelegatedCharacteristicAdapter(
+            characteristics[0],
+            encode=lambda value: bytes(value),
+            decode=VocsAudioLocation.from_bytes,
+        )
+
+        if not (
+            characteristics := service_proxy.get_characteristics_by_uuid(
+                GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC
+            )
+        ):
+            raise InvalidServiceError(
+                "Volume Offset Control Point characteristic not found"
+            )
+        self.volume_offset_control_point = characteristics[0]
+
+        if not (
+            characteristics := service_proxy.get_characteristics_by_uuid(
+                GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC
+            )
+        ):
+            raise InvalidServiceError(
+                "Audio Output Description characteristic not found"
+            )
+        self.audio_output_description = UTF8CharacteristicAdapter(characteristics[0])