feat: add new method for select device by touching on it

fido2.go

@@ -12,6 +12,7 @@ import (
 	"encoding/hex"
 	"fmt"
 	"sync"
+	"time"
 	"unsafe"
 
 	"github.com/pkg/errors"
@@ -240,6 +241,85 @@ func NewDevice(path string) (*Device, error) {
 	}, nil
 }
 
+// SelectDevice returns the first device of the passed list that is touched by the user within the given timeout.
+// It returns an error if no device was selected.
+func SelectDevice(devs []*Device, timeout time.Duration) (*Device, error) {
+	selectedDev := &Device{}
+	done := make(chan int, len(devs))
+
+	pollDevice := func(d *Device) {
+		// make sure each thread signals `done` before exiting
+		defer func() {
+			done <- 0
+		}()
+
+		dev, err := d.open()
+		if err != nil {
+			logger.Errorf("%v", errors.Wrap(err, fmt.Sprintf("failed open device %s", d.path)))
+			return
+		}
+
+		defer d.close(dev)
+
+		if cErr := C.fido_dev_get_touch_begin(dev); cErr != C.FIDO_OK {
+			msg := fmt.Sprintf("failed to start selection for %s", d.path)
+			logger.Errorf("%v", errors.Wrap(errFromCode(cErr), msg))
+			return
+		}
+
+		tick := time.Tick(200 * time.Millisecond)
+		after := time.After(timeout)
+		for {
+			select {
+			case <-tick:
+				if selectedDev.path != "" {
+					logger.Debugf(fmt.Sprintf("stop polling: %s", d.path))
+					C.fido_dev_cancel(dev)
+					return
+				}
+
+				var touched C.int
+				if cErr := C.fido_dev_get_touch_status(dev, &touched, 50); cErr != C.FIDO_OK {
+					msg := fmt.Sprintf("failed to get touch status of %s", d.path)
+					logger.Errorf("%v", errors.Wrap(errFromCode(cErr), msg))
+					C.fido_dev_cancel(dev)
+					return
+				}
+
+				if touched == 1 {
+					logger.Debugf(fmt.Sprintf("device touched: %s", d.path))
+					selectedDev.Lock()
+					if selectedDev.path == "" {
+						selectedDev.path = d.path
+					}
+					selectedDev.Unlock()
+					// call quit to stop polling for all devices
+					return
+				}
+			case <-after:
+				logger.Debugf(fmt.Sprintf("stop polling (timeout reached): %s", d.path))
+				C.fido_dev_cancel(dev)
+				return
+			}
+		}
+	}
+
+	for i := 0; i < len(devs); i++ {
+		go pollDevice(devs[i])
+	}
+
+	// wait for all threads to finish
+	for i := 0; i < len(devs); i++ {
+		<-done
+	}
+
+	if selectedDev.path == "" {
+		return nil, fmt.Errorf("timeout reached before any device was touched")
+	}
+
+	return selectedDev, nil
+}
+
 func (d *Device) open() (*C.fido_dev_t, error) {
 	dev := C.fido_dev_new()
 	if cErr := C.fido_dev_open(dev, C.CString(d.path)); cErr != C.FIDO_OK {