// Copyright 2017 Paul Nettle.
//
// This file is part of Gobbledegook.
//
// Gobbledegook is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Gobbledegook is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Gobbledegook. If not, see .
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// >>
// >>> INSIDE THIS FILE
// >>
//
// This is our representation of a GATT Characteristic which is intended to be used in our server description
//
// >>
// >>> DISCUSSION
// >>
//
// See the discussion at the top of GattCharacteristic.cpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#pragma once
#include
#include
#include
#include
#include "Utils.h"
#include "TickEvent.h"
#include "GattInterface.h"
namespace ggk {
// ---------------------------------------------------------------------------------------------------------------------------------
// Forward declarations
// ---------------------------------------------------------------------------------------------------------------------------------
struct GattCharacteristic;
struct GattDescriptor;
struct GattProperty;
struct GattService;
struct GattUuid;
struct DBusObject;
// ---------------------------------------------------------------------------------------------------------------------------------
// Useful Lambdas
// ---------------------------------------------------------------------------------------------------------------------------------
#define CHARACTERISTIC_UPDATED_VALUE_CALLBACK_LAMBDA [] \
( \
const GattCharacteristic &self, \
GDBusConnection *pConnection, \
void *pUserData \
) -> bool
#define CHARACTERISTIC_EVENT_CALLBACK_LAMBDA [] \
( \
const GattCharacteristic &self, \
const TickEvent &event, \
GDBusConnection *pConnection, \
void *pUserData \
)
#define CHARACTERISTIC_METHOD_CALLBACK_LAMBDA [] \
( \
const GattCharacteristic &self, \
GDBusConnection *pConnection, \
const std::string &methodName, \
GVariant *pParameters, \
GDBusMethodInvocation *pInvocation, \
void *pUserData \
)
// ---------------------------------------------------------------------------------------------------------------------------------
// Representation of a Bluetooth GATT Characteristic
// ---------------------------------------------------------------------------------------------------------------------------------
struct GattCharacteristic : GattInterface
{
// Our interface type
static constexpr const char *kInterfaceType = "GattCharacteristic";
typedef void (*MethodCallback)(const GattCharacteristic &self, GDBusConnection *pConnection, const std::string &methodName, GVariant *pParameters, GDBusMethodInvocation *pInvocation, void *pUserData);
typedef void (*EventCallback)(const GattCharacteristic &self, const TickEvent &event, GDBusConnection *pConnection, void *pUserData);
typedef bool (*UpdatedValueCallback)(const GattCharacteristic &self, GDBusConnection *pConnection, void *pUserData);
// Construct a GattCharacteristic
//
// Genreally speaking, these objects should not be constructed directly. Rather, use the `gattCharacteristicBegin()` method
// in `GattService`.
GattCharacteristic(DBusObject &owner, GattService &service, const std::string &name);
virtual ~GattCharacteristic() {}
// Returns a string identifying the type of interface
virtual const std::string getInterfaceType() const { return GattCharacteristic::kInterfaceType; }
// Returning the owner pops us one level up the hierarchy
//
// This method compliments `GattService::gattCharacteristicBegin()`
GattService &gattCharacteristicEnd();
// Locates a D-Bus method within this D-Bus interface and invokes the method
virtual bool callMethod(const std::string &methodName, GDBusConnection *pConnection, GVariant *pParameters, GDBusMethodInvocation *pInvocation, gpointer pUserData) const;
// Adds an event to the characteristic and returns a refereence to 'this` to enable method chaining in the server description
//
// NOTE: We specifically overload this method in order to accept our custom EventCallback type and transform it into a
// TickEvent::Callback type. We also return our own type. This simplifies the server description by allowing call to chain.
GattCharacteristic &onEvent(int tickFrequency, void *pUserData, EventCallback callback);
// Ticks events within this characteristic
//
// Note: we specifically override this method in order to translate the generic TickEvent::Callback into our own EventCallback
virtual void tickEvents(GDBusConnection *pConnection, void *pUserData) const;
// Specialized support for Characteristic ReadlValue method
//
// Defined as: array{byte} ReadValue(dict options)
//
// D-Bus breakdown:
//
// Input args: options - "a{sv}"
// Output args: value - "ay"
GattCharacteristic &onReadValue(MethodCallback callback);
// Specialized support for Characteristic WriteValue method
//
// Defined as: void WriteValue(array{byte} value, dict options)
//
// D-Bus breakdown:
//
// Input args: value - "ay"
// options - "a{sv}"
// Output args: void
GattCharacteristic &onWriteValue(MethodCallback callback);
// Custom support for handling updates to our characteristic's value
//
// Defined as: (NOT defined by Bluetooth or BlueZ - this method is internal only)
//
// This method is called by our framework whenever a characteristic's value is updated. If you need to perform any actions
// when a value is updatd, this is a good place to do that work.
//
// If you need to perform the same action(s) when a value is updated from the client (via `onWriteValue`) or from this server,
// then it may be beneficial to call this method from within your onWriteValue callback to reduce duplicated code. See
// `callOnUpdatedValue` for more information.
GattCharacteristic &onUpdatedValue(UpdatedValueCallback callback);
// Calls the onUpdatedValue method, if one was set.
//
// Returns false if there was no method set, otherwise, returns the boolean result of the method call.
//
// If you need to perform the same action(s) when a value is updated from the client (via onWriteValue) or from this server,
// then it may be beneficial to place those actions in the `onUpdatedValue` method and call it from from within your
// `onWriteValue` callback to reduce duplicated code. To call the `onUpdatedValue` method from within your `onWriteValue`, you
// can use this pattern:
//
// .onWriteValue(CHARACTERISTIC_UPDATED_VALUE_CALLBACK_LAMBDA
// {
// // Update your value
// ...
//
// // Call the onUpdateValue method that was set in the same Characteristic
// self.callOnUpdatedValue(pConnection, pUserData);
// })
bool callOnUpdatedValue(GDBusConnection *pConnection, void *pUserData) const;
// Convenience functions to add a GATT descriptor to the hierarchy
//
// We simply add a new child at the given path and add an interface configured as a GATT descriptor to it. The
// new descriptor is declared with a UUID and a variable argument list of flags (in string form.) For a complete and
// up-to-date list of flag values, see: https://git.kernel.org/pub/scm/bluetooth/bluez.git/plain/doc/gatt-api.txt
//
// At the time of this writing, the list of flags is as follows:
//
// "read"
// "write"
// "encrypt-read"
// "encrypt-write"
// "encrypt-authenticated-read"
// "encrypt-authenticated-write"
// "secure-read" (Server Only)
// "secure-write" (Server Only)
//
// To end the descriptor, call `gattDescriptorEnd()`
GattDescriptor &gattDescriptorBegin(const std::string &pathElement, const GattUuid &uuid, const std::vector &flags);
// Sends a change notification to subscribers to this characteristic
//
// This is a generalized method that accepts a `GVariant *`. A templated version is available that supports common types called
// `sendChangeNotificationValue()`.
void sendChangeNotificationVariant(GDBusConnection *pBusConnection, GVariant *pNewValue) const;
// Sends a change notification to subscribers to this characteristic
//
// This is a helper method that accepts common types. For custom types, there is a form that accepts a `GVariant *`, called
// `sendChangeNotificationVariant()`.
template
void sendChangeNotificationValue(GDBusConnection *pBusConnection, T value) const
{
GVariant *pVariant = Utils::gvariantFromByteArray(value);
sendChangeNotificationVariant(pBusConnection, pVariant);
}
protected:
GattService &service;
UpdatedValueCallback pOnUpdatedValueFunc;
};
}; // namespace ggk