added feature assert_devices

src/util.rs

@@ -0,0 +1,44 @@
+use crate::cbor::AuthenticatorData;
+use crate::{FidoAssertionRequest, FidoCredential, FidoDevice, FidoErrorKind, FidoResult};
+use std::sync::mpsc::channel;
+#[cfg(feature = "assert_devices")]
+use crossbeam::thread;
+
+/// Will send the `assertion` to all supplied `devices` and return either the first successful assertion or the last error
+#[cfg(feature = "assert_devices")]
+pub fn get_assertion_devices<'a>(
+    assertion: &'a FidoAssertionRequest,
+    devices: impl Iterator<Item = &'a mut FidoDevice>,
+) -> FidoResult<(&'a FidoCredential, AuthenticatorData)> {
+    thread::scope(
+        |scope| -> FidoResult<(&'a FidoCredential, AuthenticatorData)> {
+            let (tx, rx) = channel();
+            let handles = devices
+                .map(|device| {
+                    let cancel = device.cancel_handle()?;
+                    let tx = tx.clone();
+                    let thread_handle =
+                        scope.spawn(move |_| tx.send(device.get_assertion(assertion)));
+                    Ok((cancel, thread_handle))
+                })
+                .collect::<FidoResult<Vec<_>>>()?;
+
+            let mut err = None;
+            for res in rx.iter().take(handles.len()) {
+                match res {
+                    Ok(_) => {
+                        for (mut cancel, join) in handles {
+                            // Canceling out of courtesy don't care if it fails
+                            let _ = cancel.cancel();
+                            let _ = join.join();
+                        }
+                        return res;
+                    }
+                    e => err = Some(e),
+                }
+            }
+            err.unwrap_or(Err(FidoErrorKind::DeviceUnsupported.into()))
+        },
+    )
+    .unwrap()
+}