From 4663cffb9695f3cbf02cf621f18e6bcad287e4cc Mon Sep 17 00:00:00 2001
From: Tony Arcieri <bascule@gmail.com>
Date: Sun, 8 Dec 2019 12:12:03 -0800
Subject: [PATCH] yubikey: add `open_by_serial` method

Support for opening a `YubiKey` with a specific serial number.
---
 src/yubikey.rs | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/yubikey.rs b/src/yubikey.rs
index 7926670..3ba012d 100644
--- a/src/yubikey.rs
+++ b/src/yubikey.rs
@@ -159,8 +159,8 @@ impl YubiKey {
     /// Returns an error if there is more than one YubiKey detected.
     ///
     /// If you need to operate in environments with more than one YubiKey
-    /// attached to the same system, use [`yubikey_piv::Readers`] to select
-    /// from the available PC/SC readers connected.
+    /// attached to the same system, use [`YubiKey::open_by_serial`] or
+    ///[`yubikey_piv::Readers`] to select from the available PC/SC readers.
     pub fn open() -> Result<Self, Error> {
         let mut readers = Readers::open()?;
         let mut reader_iter = readers.iter()?;
@@ -178,6 +178,25 @@ impl YubiKey {
         Err(Error::NotFound)
     }
 
+    /// Open a YubiKey with a specific serial number.
+    pub fn open_by_serial(serial: Serial) -> Result<Self, Error> {
+        let mut readers = Readers::open()?;
+
+        for reader in readers.iter()? {
+            let mut yubikey = match reader.open() {
+                Ok(yk) => yk,
+                Err(_) => continue,
+            };
+
+            if serial == yubikey.serial() {
+                return Ok(yubikey);
+            }
+        }
+
+        error!("no YubiKey detected with serial: {}", serial);
+        Err(Error::NotFound)
+    }
+
     /// Reconnect to a YubiKey
     #[cfg(feature = "untested")]
     pub fn reconnect(&mut self) -> Result<(), Error> {