Add list_devices function

This patch adds support for libnitrokey’s NK_list_devices function by
introducing the top-level list_devices function.  It returns a vector of
DeviceInfo structs with information about all connected Nitrokey
devices.

4 files changed, 105 insertions, 6 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3798540..15c76b3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ SPDX-License-Identifier: CC0-1.0
 - Implement connection by path:
   - Add the `Error::UnsupportedDeviceError` variant.
   - Add the `DeviceInfo` struct.
+  - Add the `list_devices` function.
 
 # v0.4.0 (2020-01-02)
 - Remove the `test-pro` and `test-storage` features.
diff --git a/TODO.md b/TODO.md
index 8adea87..e3708f9 100644
--- a/TODO.md
+++ b/TODO.md
@@ -8,8 +8,6 @@ SPDX-License-Identifier: CC0-1.0
     - `NK_get_SD_usage_data`
     - `NK_get_progress_bar_value`
     - `NK_get_status` -- waiting for [libnitrokey issue 166][]
-    - `NK_list_devices`
-    - `NK_free_device_info`
     - `NK_connect_with_path`
 - Clear passwords from memory.
 - Lock password safe in `PasswordSafe::drop()` (see [nitrokey-storage-firmware
diff --git a/src/lib.rs b/src/lib.rs
index dad4a20..5600d24 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -109,8 +109,10 @@ mod otp;
 mod pws;
 mod util;
 
+use std::convert::TryInto as _;
 use std::fmt;
 use std::marker;
+use std::ptr::NonNull;
 use std::sync;
 
 use nitrokey_sys;
@@ -126,6 +128,8 @@ pub use crate::otp::{ConfigureOtp, GenerateOtp, OtpMode, OtpSlotData};
 pub use crate::pws::{GetPasswordSafe, PasswordSafe, SLOT_COUNT};
 pub use crate::util::LogLevel;
 
+use crate::util::get_last_result;
+
 /// The default admin PIN for all Nitrokey devices.
 pub const DEFAULT_ADMIN_PIN: &str = "12345678";
 /// The default user PIN for all Nitrokey devices.
@@ -416,6 +420,70 @@ pub fn force_take() -> Result<sync::MutexGuard<'static, Manager>, Error> {
     }
 }
 
+/// List all connected Nitrokey devices.
+///
+/// This functions returns a vector with [`DeviceInfo`][] structs that contain information about
+/// all connected Nitrokey devices.  It will even list unsupported models, although you cannot
+/// connect to them.
+///
+/// # Errors
+///
+/// - [`NotConnected`][] if a Nitrokey device has been disconnected during enumeration
+/// - [`Utf8Error`][] if the USB path or the serial number returned by libnitrokey are invalid
+///   UTF-8 strings
+///
+/// # Example
+///
+/// ```
+/// let devices = nitrokey::list_devices()?;
+/// if devices.is_empty() {
+///     println!("No connected Nitrokey devices found.");
+/// } else {
+///     println!("model\tpath\tserial number");
+///     for device in devices {
+///         match device.model {
+///             Some(model) => print!("{}", model),
+///             None => print!("unsupported"),
+///         }
+///         print!("\t{}\t", device.path);
+///         match device.serial_number {
+///             Some(serial_number) => println!("{}", serial_number),
+///             None => println!("unknown"),
+///         }
+///     }
+/// }
+/// # Ok::<(), nitrokey::Error>(())
+/// ```
+///
+/// [`DeviceInfo`]: struct.DeviceInfo.html
+/// [`NotConnected`]: enum.CommunicationError.html#variant.NotConnected
+/// [`Utf8Error`]: enum.Error.html#variant.Utf8Error
+pub fn list_devices() -> Result<Vec<DeviceInfo>, Error> {
+    let ptr = NonNull::new(unsafe { nitrokey_sys::NK_list_devices() });
+    match ptr {
+        Some(mut ptr) => {
+            let mut vec: Vec<DeviceInfo> = Vec::new();
+            push_device_info(&mut vec, unsafe { ptr.as_ref() })?;
+            unsafe {
+                nitrokey_sys::NK_free_device_info(ptr.as_mut());
+            }
+            Ok(vec)
+        }
+        None => get_last_result().map(|_| Vec::new()),
+    }
+}
+
+fn push_device_info(
+    vec: &mut Vec<DeviceInfo>,
+    info: &nitrokey_sys::NK_device_info,
+) -> Result<(), Error> {
+    vec.push(info.try_into()?);
+    if let Some(ptr) = NonNull::new(info.next) {
+        push_device_info(vec, unsafe { ptr.as_ref() })?;
+    }
+    Ok(())
+}
+
 /// Enables or disables debug output.  Calling this method with `true` is equivalent to setting the
 /// log level to `Debug`; calling it with `false` is equivalent to the log level `Error` (see
 /// [`set_log_level`][]).
diff --git a/tests/device.rs b/tests/device.rs
index e367558..5e60002 100644
--- a/tests/device.rs
+++ b/tests/device.rs
@@ -8,8 +8,8 @@ use std::process::Command;
 use std::{thread, time};
 
 use nitrokey::{
-    Authenticate, CommandError, CommunicationError, Config, ConfigureOtp, Device, Error,
-    GenerateOtp, GetPasswordSafe, LibraryError, OtpMode, OtpSlotData, Storage, VolumeMode,
+    Authenticate, CommandError, CommunicationError, Config, ConfigureOtp, Device, DeviceInfo,
+    Error, GenerateOtp, GetPasswordSafe, LibraryError, OtpMode, OtpSlotData, Storage, VolumeMode,
     DEFAULT_ADMIN_PIN, DEFAULT_USER_PIN,
 };
 use nitrokey_test::test as test_device;
@@ -32,6 +32,33 @@ fn count_nitrokey_block_devices() -> usize {
 }
 
 #[test_device]
+fn list_no_devices() {
+    let devices = nitrokey::list_devices();
+    assert_ok!(Vec::<DeviceInfo>::new(), devices);
+}
+
+#[test_device]
+fn list_devices(_device: DeviceWrapper) {
+    let devices = unwrap_ok!(nitrokey::list_devices());
+    for device in devices {
+        assert!(!device.path.is_empty());
+        if let Some(model) = device.model {
+            match model {
+                nitrokey::Model::Pro => {
+                    assert!(device.serial_number.is_some());
+                    let serial_number = device.serial_number.unwrap();
+                    assert!(!serial_number.is_empty());
+                    assert_valid_serial_number(&serial_number);
+                },
+                nitrokey::Model::Storage => {
+                    assert_eq!(None, device.serial_number);
+                },
+            }
+        }
+    }
+}
+
+#[test_device]
 fn connect_no_device() {
     let mut manager = unwrap_ok!(nitrokey::take());
 
@@ -83,12 +110,17 @@ fn disconnect(device: DeviceWrapper) {
     assert_empty_serial_number();
 }
 
+fn assert_valid_serial_number(serial_number: &str) {
+    assert!(serial_number.is_ascii());
+    assert!(serial_number.chars().all(|c| c.is_ascii_hexdigit()));
+}
+
 #[test_device]
 fn get_serial_number(device: DeviceWrapper) {
     let serial_number = unwrap_ok!(device.get_serial_number());
-    assert!(serial_number.is_ascii());
-    assert!(serial_number.chars().all(|c| c.is_ascii_hexdigit()));
+    assert_valid_serial_number(&serial_number);
 }
+
 #[test_device]
 fn get_firmware_version(device: Pro) {
     let version = unwrap_ok!(device.get_firmware_version());