Add service-filtered BLE scanning on macOS

darwin/device.go

@@ -93,6 +93,16 @@ func (d *Device) Option(opts ...ble.Option) error {
 //
 // Concurrent Scan operations will result in undefined behavior.
 func (d *Device) Scan(ctx context.Context, allowDup bool, h ble.AdvHandler) error {
+	return d.scan(ctx, allowDup, h, nil)
+}
+
+// ScanWithServices behaves like Scan but forwards the service UUID filter to
+// CoreBluetooth so macOS will request scan responses for matching devices.
+func (d *Device) ScanWithServices(ctx context.Context, allowDup bool, h ble.AdvHandler, services []ble.UUID) error {
+	return d.scan(ctx, allowDup, h, services)
+}
+
+func (d *Device) scan(ctx context.Context, allowDup bool, h ble.AdvHandler, services []ble.UUID) error {
 	// Because the OS delivers results to the delegate
 	// DidDiscoverPeripheral concurrently, we need a way to handle
 	// events when a Scan is in progress, and safely discard them
@@ -117,7 +127,7 @@ func (d *Device) Scan(ctx context.Context, allowDup bool, h ble.AdvHandler) erro
 
 	// Start scanning, and stop scanning when the context expires.
 	go func() {
-		d.cm.Scan(nil, &cbgo.CentralManagerScanOpts{
+		d.cm.Scan(uuidsToCbgoUUIDs(services), &cbgo.CentralManagerScanOpts{
 			AllowDuplicates: allowDup,
 		})
 		<-ctx.Done()

gatt.go

@@ -14,6 +14,10 @@ var ErrDefaultDevice = errors.New("default device is not set")
 
 var defaultDevice Device
 
+type serviceScanner interface {
+	ScanWithServices(ctx context.Context, allowDup bool, h AdvHandler, services []UUID) error
+}
+
 // SetDefaultDevice returns the default HCI device.
 func SetDefaultDevice(d Device) {
 	defaultDevice = d
@@ -100,6 +104,35 @@ func Scan(ctx context.Context, allowDup bool, h AdvHandler, f AdvFilter) error {
 	return defaultDevice.Scan(ctx, allowDup, h2)
 }
 
+// ScanWithServices starts scanning while requesting that the backend use the
+// provided service UUIDs as native scan filters when supported.
+func ScanWithServices(ctx context.Context, allowDup bool, h AdvHandler, f AdvFilter, services []UUID) error {
+	if defaultDevice == nil {
+		return ErrDefaultDevice
+	}
+	defer untrap(trap(ctx))
+
+	if len(services) == 0 {
+		return Scan(ctx, allowDup, h, f)
+	}
+
+	scanner, ok := defaultDevice.(serviceScanner)
+	if !ok {
+		return Scan(ctx, allowDup, h, f)
+	}
+
+	if f == nil {
+		return scanner.ScanWithServices(ctx, allowDup, h, services)
+	}
+
+	h2 := func(a Advertisement) {
+		if f(a) {
+			h(a)
+		}
+	}
+	return scanner.ScanWithServices(ctx, allowDup, h2, services)
+}
+
 // Find ...
 func Find(ctx context.Context, allowDup bool, f AdvFilter) ([]Advertisement, error) {
 	if defaultDevice == nil {