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// Copyright 2022 The Pigweed Authors
//
// 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.
#pragma once
#include <cstdint>
#include <optional>
#include "pw_bluetooth/types.h"
#include "pw_span/span.h"
namespace pw::bluetooth::gatt {
// A Handle uniquely identifies a service, characteristic, or descriptor.
enum class Handle : uint64_t {};
// Possible values for the characteristic properties bitfield. These specify
// the GATT procedures that are allowed for a particular characteristic.
enum class CharacteristicPropertyBits : uint16_t {
kBroadcast = 0x1,
kRead = 0x2,
kWriteWithoutResponse = 0x4,
kWrite = 0x8,
kNotify = 0x10,
kIndicate = 0x20,
kAuthenticatedSignedWrites = 0x40,
kReliableWrite = 0x100,
kWritableAuxiliaries = 0x200
};
// Helper operators to allow combining and comparing CharacteristicPropertyBits
// values.
inline constexpr bool operator&(CharacteristicPropertyBits left,
CharacteristicPropertyBits right) {
return static_cast<bool>(
static_cast<std::underlying_type_t<CharacteristicPropertyBits>>(left) &
static_cast<std::underlying_type_t<CharacteristicPropertyBits>>(right));
}
inline constexpr CharacteristicPropertyBits operator|(
CharacteristicPropertyBits left, CharacteristicPropertyBits right) {
return static_cast<CharacteristicPropertyBits>(
static_cast<std::underlying_type_t<CharacteristicPropertyBits>>(left) |
static_cast<std::underlying_type_t<CharacteristicPropertyBits>>(right));
}
inline constexpr CharacteristicPropertyBits& operator|=(
CharacteristicPropertyBits& left, CharacteristicPropertyBits right) {
return left = left | right;
}
// Represents encryption, authentication, and authorization permissions that can
// be assigned to a specific access permission.
struct SecurityRequirements {
// If true, the physical link must be encrypted to access this attribute.
bool encryption_required;
// If true, the physical link must be authenticated to access this
// attribute.
bool authentication_required;
// If true, the client needs to be authorized before accessing this
// attribute.
bool authorization_required;
};
/// Specifies the access permissions for a specific attribute value.
struct AttributePermissions {
// Specifies whether or not an attribute has the read permission. If null,
// then the attribute value cannot be read. Otherwise, it can be read only if
// the permissions specified in the SecurityRequirements table are satisfied.
std::optional<SecurityRequirements> read;
// Specifies whether or not an attribute has the write permission. If null,
// then the attribute value cannot be written. Otherwise, it can be written
// only if the permissions specified in the SecurityRequirements table are
// satisfied.
std::optional<SecurityRequirements> write;
// Specifies the security requirements for a client to subscribe to
// notifications or indications on a characteristic. A characteristic's
// support for notifications or indications is specified using the NOTIFY and
// INDICATE characteristic properties. If a local characteristic has one of
// these properties then this field can not be null. Otherwise, this field
// must be left as null.
//
// This field is ignored for Descriptors.
std::optional<SecurityRequirements> update;
};
// Represents a local or remote GATT characteristic descriptor.
struct Descriptor {
// Uniquely identifies this descriptor within a service.
// For local descriptors, the specified handle must be unique
// across all characteristic and descriptor handles in this service.
Handle handle;
// The UUID that identifies the type of this descriptor.
Uuid type;
// The attribute permissions of this descriptor. For remote descriptors, this
// value will be null until the permissions are discovered via read and write
// requests.
std::optional<AttributePermissions> permissions;
};
// Represents a local or remote GATT characteristic.
struct Characteristic {
// Uniquely identifies this characteristic within a service.
// For local characteristics, the specified handle must be unique across
// all characteristic and descriptor handles in this service.
Handle handle;
// The UUID that identifies the type of this characteristic.
Uuid type;
// The characteristic properties bitfield. This is a logic or of any number of
// values from `CharacteristicPropertyBits` above.
CharacteristicPropertyBits properties;
// The attribute permissions of this characteristic. For remote
// characteristics, this value will be null until the permissions are
// discovered via read and write requests.
std::optional<AttributePermissions> permissions;
// The descriptors of this characteristic.
span<const Descriptor> descriptors;
};
} // namespace pw::bluetooth::gatt
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