Add ScanFilter to Central::start_scan()

Author: paroga

examples/discover_adapters_peripherals.rs

@@ -5,7 +5,7 @@ use std::error::Error;
 use std::time::Duration;
 use tokio::time;
 
-use btleplug::api::{Central, Manager as _, Peripheral};
+use btleplug::api::{Central, Manager as _, Peripheral, ScanFilter};
 use btleplug::platform::Manager;
 
 #[tokio::main]
@@ -21,7 +21,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
     for adapter in adapter_list.iter() {
         println!("Starting scan...");
         adapter
-            .start_scan()
+            .start_scan(ScanFilter::default())
             .await
             .expect("Can't scan BLE adapter for connected devices...");
         time::sleep(Duration::from_secs(10)).await;

examples/event_driven_discovery.rs

@@ -1,7 +1,7 @@
 // See the "macOS permissions note" in README.md before running this on macOS
 // Big Sur or later.
 
-use btleplug::api::{bleuuid::BleUuid, Central, CentralEvent, Manager as _};
+use btleplug::api::{bleuuid::BleUuid, Central, CentralEvent, Manager as _, ScanFilter};
 use btleplug::platform::{Adapter, Manager};
 use futures::stream::StreamExt;
 use std::error::Error;
@@ -33,7 +33,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
     let mut events = central.events().await?;
 
     // start scanning for devices
-    central.start_scan().await?;
+    central.start_scan(ScanFilter::default()).await?;
 
     // Print based on whatever the event receiver outputs. Note that the event
     // receiver blocks, so in a real program, this should be run in its own

examples/lights.rs

@@ -1,7 +1,9 @@
 // See the "macOS permissions note" in README.md before running this on macOS
 // Big Sur or later.
 
-use btleplug::api::{bleuuid::uuid_from_u16, Central, Manager as _, Peripheral as _, WriteType};
+use btleplug::api::{
+    bleuuid::uuid_from_u16, Central, Manager as _, Peripheral as _, ScanFilter, WriteType,
+};
 use btleplug::platform::{Adapter, Manager, Peripheral};
 use rand::{thread_rng, Rng};
 use std::error::Error;
@@ -43,7 +45,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
         .expect("Unable to find adapters.");
 
     // start scanning for devices
-    central.start_scan().await?;
+    central.start_scan(ScanFilter::default()).await?;
     // instead of waiting, you can use central.event_receiver() to get a channel
     // to listen for notifications on.
     time::sleep(Duration::from_secs(2)).await;

examples/subscribe_notify_characteristic.rs

@@ -1,8 +1,7 @@
 // See the "macOS permissions note" in README.md before running this on macOS
 // Big Sur or later.
 
-use btleplug::api::CharPropFlags;
-use btleplug::api::{Central, Manager as _, Peripheral};
+use btleplug::api::{Central, CharPropFlags, Manager as _, Peripheral, ScanFilter};
 use btleplug::platform::Manager;
 use futures::stream::StreamExt;
 use std::error::Error;
@@ -26,7 +25,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
     for adapter in adapter_list.iter() {
         println!("Starting scan...");
         adapter
-            .start_scan()
+            .start_scan(ScanFilter::default())
             .await
             .expect("Can't scan BLE adapter for connected devices...");
         time::sleep(Duration::from_secs(2)).await;

src/api/mod.rs

@@ -180,6 +180,14 @@ pub struct PeripheralProperties {
     pub services: Vec<Uuid>,
 }
 
+/// The filter used when scanning for BLE devices.
+#[derive(Debug, Default, Clone)]
+pub struct ScanFilter {
+    /// If the filter contains at least one service UUID, only devices supporting at least one of
+    /// the given services will be available.
+    pub services: Vec<Uuid>,
+}
+
 /// The type of write operation to use.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum WriteType {
@@ -299,7 +307,11 @@ pub trait Central: Send + Sync + Clone {
     /// Starts a scan for BLE devices. This scan will generally continue until explicitly stopped,
     /// although this may depend on your Bluetooth adapter. Discovered devices will be announced
     /// to subscribers of `events` and will be available via `peripherals()`.
-    async fn start_scan(&self) -> Result<()>;
+    /// The filter can be used to scan only for specific devices. While some implementations migth
+    /// ignore (parts of) the filter and make additional devices available, other implementations
+    /// might require at least one filter for security reasons. Cross-platform code should provide
+    /// a filter, but must be able to handle devices, which do not fit into the filter.
+    async fn start_scan(&self, filter: ScanFilter) -> Result<()>;
 
     /// Stops scanning for BLE devices.
     async fn stop_scan(&self) -> Result<()>;

src/bluez/adapter.rs

@@ -1,5 +1,5 @@
 use super::peripheral::{Peripheral, PeripheralId};
-use crate::api::{BDAddr, Central, CentralEvent};
+use crate::api::{BDAddr, Central, CentralEvent, ScanFilter};
 use crate::{Error, Result};
 use async_trait::async_trait;
 use bluez_async::{
@@ -46,8 +46,9 @@ impl Central for Adapter {
         Ok(Box::pin(initial_events.chain(events)))
     }
 
-    async fn start_scan(&self) -> Result<()> {
+    async fn start_scan(&self, filter: ScanFilter) -> Result<()> {
         let filter = DiscoveryFilter {
+            service_uuids: filter.services,
             transport: Some(Transport::Auto),
             ..Default::default()
         };

src/corebluetooth/adapter.rs

@@ -1,6 +1,6 @@
 use super::internal::{run_corebluetooth_thread, CoreBluetoothEvent, CoreBluetoothMessage};
 use super::peripheral::{Peripheral, PeripheralId};
-use crate::api::{BDAddr, Central, CentralEvent};
+use crate::api::{BDAddr, Central, CentralEvent, ScanFilter};
 use crate::common::adapter_manager::AdapterManager;
 use crate::{Error, Result};
 use async_trait::async_trait;
@@ -87,10 +87,10 @@ impl Central for Adapter {
         Ok(self.manager.event_stream())
     }
 
-    async fn start_scan(&self) -> Result<()> {
+    async fn start_scan(&self, filter: ScanFilter) -> Result<()> {
         self.sender
             .to_owned()
-            .send(CoreBluetoothMessage::StartScanning)
+            .send(CoreBluetoothMessage::StartScanning { filter })
             .await?;
         Ok(())
     }

src/corebluetooth/internal.rs

@@ -17,7 +17,7 @@ use super::{
     future::{BtlePlugFuture, BtlePlugFutureStateShared},
     utils::{core_bluetooth::cbuuid_to_uuid, nsstring::nsstring_to_string, nsuuid_to_uuid},
 };
-use crate::api::{CharPropFlags, Characteristic, Service, WriteType};
+use crate::api::{CharPropFlags, Characteristic, ScanFilter, Service, WriteType};
 use crate::Error;
 use futures::channel::mpsc::{self, Receiver, Sender};
 use futures::select;
@@ -258,7 +258,9 @@ impl Debug for CoreBluetoothInternal {
 
 #[derive(Debug)]
 pub enum CoreBluetoothMessage {
-    StartScanning,
+    StartScanning {
+        filter: ScanFilter,
+    },
     StopScanning,
     ConnectDevice {
         peripheral_uuid: Uuid,
@@ -762,7 +764,7 @@ impl CoreBluetoothInternal {
             adapter_msg = self.message_receiver.select_next_some() => {
                 trace!("Adapter message!");
                 match adapter_msg {
-                    CoreBluetoothMessage::StartScanning => self.start_discovery(),
+                    CoreBluetoothMessage::StartScanning{filter} => self.start_discovery(filter),
                     CoreBluetoothMessage::StopScanning => self.stop_discovery(),
                     CoreBluetoothMessage::ConnectDevice{peripheral_uuid, future} => {
                         trace!("got connectdevice msg!");
@@ -793,14 +795,15 @@ impl CoreBluetoothInternal {
         }
     }
 
-    fn start_discovery(&mut self) {
+    fn start_discovery(&mut self, _filter: ScanFilter) {
         trace!("BluetoothAdapter::start_discovery");
         let options = ns::mutabledictionary();
         // NOTE: If duplicates are not allowed then a peripheral will not show
         // up again once connected and then disconnected.
         ns::mutabledictionary_setobject_forkey(options, ns::number_withbool(YES), unsafe {
             cb::CENTRALMANAGERSCANOPTIONALLOWDUPLICATESKEY
         });
+        // TODO: set cb::CBCENTRALMANAGERSCANOPTIONSOLICITEDSERVICEUUIDSKEY with filter.services
         cb::centralmanager_scanforperipherals_options(*self.manager, options);
     }
 

src/winrtble/adapter.rs

@@ -13,7 +13,7 @@
 
 use super::{ble::watcher::BLEWatcher, peripheral::Peripheral, peripheral::PeripheralId};
 use crate::{
-    api::{BDAddr, Central, CentralEvent},
+    api::{BDAddr, Central, CentralEvent, ScanFilter},
     common::adapter_manager::AdapterManager,
     Error, Result,
 };
@@ -55,7 +55,8 @@ impl Central for Adapter {
         Ok(self.manager.event_stream())
     }
 
-    async fn start_scan(&self) -> Result<()> {
+    async fn start_scan(&self, _filter: ScanFilter) -> Result<()> {
+        // TODO: implement filter
         let watcher = self.watcher.lock().unwrap();
         let manager = self.manager.clone();
         watcher.start(Box::new(move |args| {