Requesting MTU

Cargo.toml

@@ -38,7 +38,7 @@ tokio-stream = { version = "0.1.16", features = ["sync"] }
 
 [target.'cfg(target_os = "linux")'.dependencies]
 dbus = "0.9.7"
-bluez-async = "0.7.2"
+bluez-async = "0.8.0"
 
 [target.'cfg(target_os = "android")'.dependencies]
 jni = "0.19.0"

src/api/mod.rs

@@ -43,6 +43,9 @@ pub use self::bdaddr::{BDAddr, ParseBDAddrError};
 
 use crate::platform::PeripheralId;
 
+/// The default MTU size for a peripheral.
+pub const DEFAULT_MTU_SIZE: u16 = 23;
+
 #[cfg_attr(
     feature = "serde",
     derive(Serialize, Deserialize),
@@ -230,6 +233,9 @@ pub trait Peripheral: Send + Sync + Clone + Debug {
     /// Returns the MAC address of the peripheral.
     fn address(&self) -> BDAddr;
 
+    /// Returns the currently negotiated mtu size
+    fn mtu(&self) -> u16;
+
     /// Returns the set of properties associated with the peripheral. These may be updated over time
     /// as additional advertising reports are received.
     async fn properties(&self) -> Result<Option<PeripheralProperties>>;

src/bluez/peripheral.rs

@@ -138,6 +138,17 @@ impl api::Peripheral for Peripheral {
         self.mac_address
     }
 
+    fn mtu(&self) -> u16 {
+        let services = self.services.lock().unwrap();
+        for (_, service) in services.iter() {
+            for (_, characteristic) in service.characteristics.iter() {
+                return characteristic.info.mtu.unwrap();
+            }
+        }
+
+        api::DEFAULT_MTU_SIZE
+    }
+
     async fn properties(&self) -> Result<Option<PeripheralProperties>> {
         let device_info = self.device_info().await?;
         Ok(Some(PeripheralProperties {

src/winrtble/ble/device.rs

@@ -18,28 +18,37 @@ use windows::{
         BluetoothCacheMode, BluetoothConnectionStatus, BluetoothLEDevice,
         GenericAttributeProfile::{
             GattCharacteristic, GattCommunicationStatus, GattDescriptor, GattDeviceService,
-            GattDeviceServicesResult,
+            GattDeviceServicesResult, GattSession,
         },
     },
     Foundation::{EventRegistrationToken, TypedEventHandler},
 };
 
 pub type ConnectedEventHandler = Box<dyn Fn(bool) + Send>;
+pub type MaxPduSizeChangedEventHandler = Box<dyn Fn(u16) + Send>;
 
 pub struct BLEDevice {
     device: BluetoothLEDevice,
+    gatt_session: GattSession,
     connection_token: EventRegistrationToken,
+    pdu_change_token: EventRegistrationToken,
     services: Vec<GattDeviceService>,
 }
 
 impl BLEDevice {
     pub async fn new(
         address: BDAddr,
         connection_status_changed: ConnectedEventHandler,
+        max_pdu_size_changed: MaxPduSizeChangedEventHandler,
     ) -> Result<Self> {
         let async_op = BluetoothLEDevice::FromBluetoothAddressAsync(address.into())
             .map_err(|_| Error::DeviceNotFound)?;
         let device = async_op.await.map_err(|_| Error::DeviceNotFound)?;
+
+        let async_op = GattSession::FromDeviceIdAsync(&device.BluetoothDeviceId()?)
+            .map_err(|_| Error::DeviceNotFound)?;
+        let gatt_session = async_op.await.map_err(|_| Error::DeviceNotFound)?;
+
         let connection_status_handler =
             TypedEventHandler::new(move |sender: &Option<BluetoothLEDevice>, _| {
                 if let Some(sender) = sender {
@@ -57,9 +66,23 @@ impl BLEDevice {
             .ConnectionStatusChanged(&connection_status_handler)
             .map_err(|_| Error::Other("Could not add connection status handler".into()))?;
 
+        max_pdu_size_changed(gatt_session.MaxPduSize().unwrap());
+        let max_pdu_size_changed_handler =
+            TypedEventHandler::new(move |sender: &Option<GattSession>, _| {
+                if let Some(sender) = sender {
+                    max_pdu_size_changed(sender.MaxPduSize().unwrap());
+                }
+                Ok(())
+            });
+        let pdu_change_token = gatt_session
+            .MaxPduSizeChanged(&max_pdu_size_changed_handler)
+            .map_err(|_| Error::Other("Could not add max pdu size changed handler".into()))?;
+
         Ok(BLEDevice {
             device,
+            gatt_session,
             connection_token,
+            pdu_change_token,
             services: vec![],
         })
     }
@@ -167,6 +190,13 @@ impl BLEDevice {
 
 impl Drop for BLEDevice {
     fn drop(&mut self) {
+        let result = self
+            .gatt_session
+            .RemoveMaxPduSizeChanged(self.pdu_change_token);
+        if let Err(err) = result {
+            debug!("Drop: remove_max_pdu_size_changed {:?}", err);
+        }
+
         let result = self
             .device
             .RemoveConnectionStatusChanged(self.connection_token);

src/winrtble/peripheral.rs

@@ -37,7 +37,7 @@ use std::{
     convert::TryInto,
     fmt::{self, Debug, Display, Formatter},
     pin::Pin,
-    sync::atomic::{AtomicBool, Ordering},
+    sync::atomic::{AtomicBool, AtomicU16, Ordering},
     sync::{Arc, RwLock},
 };
 use tokio::sync::broadcast;
@@ -70,6 +70,7 @@ struct Shared {
     device: tokio::sync::Mutex<Option<BLEDevice>>,
     adapter: Weak<AdapterManager<Peripheral>>,
     address: BDAddr,
+    mtu: AtomicU16,
     connected: AtomicBool,
     ble_services: DashMap<Uuid, BLEService>,
     notifications_channel: broadcast::Sender<ValueNotification>,
@@ -93,6 +94,7 @@ impl Peripheral {
                 adapter,
                 device: tokio::sync::Mutex::new(None),
                 address,
+                mtu: AtomicU16::new(api::DEFAULT_MTU_SIZE),
                 connected: AtomicBool::new(false),
                 ble_services: DashMap::new(),
                 notifications_channel: broadcast_sender,
@@ -341,6 +343,11 @@ impl ApiPeripheral for Peripheral {
         self.shared.address
     }
 
+    /// Returns the currently negotiated mtu size
+    fn mtu(&self) -> u16 {
+        self.shared.mtu.load(Ordering::Relaxed)
+    }
+
     /// Returns the set of properties associated with the peripheral. These may be updated over time
     /// as additional advertising reports are received.
     async fn properties(&self) -> Result<Option<PeripheralProperties>> {
@@ -364,12 +371,12 @@ impl ApiPeripheral for Peripheral {
     /// Ok there has been successful connection. Note that peripherals allow only one connection at
     /// a time. Operations that attempt to communicate with a device will fail until it is connected.
     async fn connect(&self) -> Result<()> {
-        let shared_clone = Arc::downgrade(&self.shared);
         let adapter_clone = self.shared.adapter.clone();
         let address = self.shared.address;
-        let device = BLEDevice::new(
-            self.shared.address,
-            Box::new(move |is_connected| {
+
+        let connection_status_changed = Box::new({
+            let shared_clone = Arc::downgrade(&self.shared);
+            move |is_connected| {
                 if let Some(shared) = shared_clone.upgrade() {
                     shared.connected.store(is_connected, Ordering::Relaxed);
                 }
@@ -379,7 +386,22 @@ impl ApiPeripheral for Peripheral {
                         adapter.emit(CentralEvent::DeviceDisconnected(address.into()));
                     }
                 }
-            }),
+            }
+        });
+
+        let max_pdu_size_changed = Box::new({
+            let shared_clone = Arc::downgrade(&self.shared);
+            move |mtu| {
+                if let Some(shared) = shared_clone.upgrade() {
+                    shared.mtu.store(mtu, Ordering::Relaxed);
+                }
+            }
+        });
+
+        let device = BLEDevice::new(
+            self.shared.address,
+            connection_status_changed,
+            max_pdu_size_changed,
         )
         .await?;