Merge branch 'connect_path' into next

This patch series adds the list_devices function that returns a list of
available Nitrokey devices and the Manager::connect_path function that
connects to one of the available devices.

6 files changed, 341 insertions, 25 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 71d2377..abdcab7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,11 @@ SPDX-License-Identifier: CC0-1.0
   - `NK_enable_firmware_update_pro`
   - `NK_list_devices_by_cpuID`
   - `NK_send_startup`
+- Implement connection by path:
+  - Add the `Error::UnsupportedDeviceError` variant.
+  - Add the `DeviceInfo` struct.
+  - Add the `list_devices` function.
+  - Add the `connect_path` function to the `Manager` struct.
 
 # v0.4.0 (2020-01-02)
 - Remove the `test-pro` and `test-storage` features.
diff --git a/TODO.md b/TODO.md
index 8adea87..eba14be 100644
--- a/TODO.md
+++ b/TODO.md
@@ -8,9 +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
   issue 65][]).
diff --git a/src/device/mod.rs b/src/device/mod.rs
index 5e15f08..e015886 100644
--- a/src/device/mod.rs
+++ b/src/device/mod.rs
@@ -5,6 +5,9 @@ mod pro;
 mod storage;
 mod wrapper;
 
+use std::cmp;
+use std::convert::{TryFrom, TryInto};
+use std::ffi;
 use std::fmt;
 
 use libc;
@@ -16,7 +19,8 @@ use crate::error::{CommunicationError, Error};
 use crate::otp::GenerateOtp;
 use crate::pws::GetPasswordSafe;
 use crate::util::{
-    get_command_result, get_cstring, get_last_error, result_from_string, result_or_error,
+    get_command_result, get_cstring, get_last_error, owned_str_from_ptr, result_from_string,
+    result_or_error,
 };
 
 pub use pro::Pro;
@@ -43,6 +47,97 @@ impl fmt::Display for Model {
     }
 }
 
+impl From<Model> for nitrokey_sys::NK_device_model {
+    fn from(model: Model) -> Self {
+        match model {
+            Model::Storage => nitrokey_sys::NK_device_model_NK_STORAGE,
+            Model::Pro => nitrokey_sys::NK_device_model_NK_PRO,
+        }
+    }
+}
+
+impl TryFrom<nitrokey_sys::NK_device_model> for Model {
+    type Error = Error;
+
+    fn try_from(model: nitrokey_sys::NK_device_model) -> Result<Self, Error> {
+        match model {
+            nitrokey_sys::NK_device_model_NK_DISCONNECTED => {
+                Err(CommunicationError::NotConnected.into())
+            }
+            nitrokey_sys::NK_device_model_NK_PRO => Ok(Model::Pro),
+            nitrokey_sys::NK_device_model_NK_STORAGE => Ok(Model::Storage),
+            _ => Err(Error::UnsupportedModelError),
+        }
+    }
+}
+
+/// Connection information for a Nitrokey device.
+#[derive(Clone, Debug, PartialEq)]
+pub struct DeviceInfo {
+    /// The model of the Nitrokey device, or `None` if the model is not supported by this crate.
+    pub model: Option<Model>,
+    /// The USB device path.
+    pub path: String,
+    /// The serial number as a 8-character hex string, or `None` if the device does not expose its
+    /// serial number.
+    pub serial_number: Option<String>,
+}
+
+impl TryFrom<&nitrokey_sys::NK_device_info> for DeviceInfo {
+    type Error = Error;
+
+    fn try_from(device_info: &nitrokey_sys::NK_device_info) -> Result<DeviceInfo, Error> {
+        let model_result = device_info.model.try_into();
+        let model_option = model_result.map(Some).or_else(|err| match err {
+            Error::UnsupportedModelError => Ok(None),
+            _ => Err(err),
+        })?;
+        let serial_number = unsafe { ffi::CStr::from_ptr(device_info.serial_number) }
+            .to_str()
+            .map_err(Error::from)?;
+        Ok(DeviceInfo {
+            model: model_option,
+            path: owned_str_from_ptr(device_info.path)?,
+            serial_number: get_hidapi_serial_number(serial_number),
+        })
+    }
+}
+
+impl fmt::Display for DeviceInfo {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.model {
+            Some(model) => write!(f, "Nitrokey {}", model)?,
+            None => write!(f, "Unsupported Nitrokey model")?,
+        }
+        write!(f, " at {} with ", self.path)?;
+        match &self.serial_number {
+            Some(ref serial_number) => write!(f, "serial no. {}", serial_number),
+            None => write!(f, "an unknown serial number"),
+        }
+    }
+}
+
+/// Parses a serial number returned by hidapi and transforms it to the Nitrokey format.
+///
+/// If the serial number is all zero, this function returns `None`.  Otherwise, all leading zeros
+/// (except the last eight characters) are stripped and `Some(_)` is returned.  If the serial
+/// number has less than eight characters, leading zeros are added.
+fn get_hidapi_serial_number(serial_number: &str) -> Option<String> {
+    let mut iter = serial_number.char_indices().skip_while(|(_, c)| *c == '0');
+    let first_non_null = iter.next();
+    if let Some((i, _)) = first_non_null {
+        // keep at least the last 8 characters
+        let len = serial_number.len();
+        let cut = cmp::min(len.saturating_sub(8), i);
+        let (_, suffix) = serial_number.split_at(cut);
+        // if necessary, add leading zeros to reach 8 characters
+        let fill = 8usize.saturating_sub(len);
+        Some("0".repeat(fill) + suffix)
+    } else {
+        None
+    }
+}
+
 /// A firmware version for a Nitrokey device.
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub struct FirmwareVersion {
@@ -428,12 +523,8 @@ pub trait Device<'a>: Authenticate<'a> + GetPasswordSafe<'a> + GenerateOtp + fmt
     }
 }
 
-fn get_connected_model() -> Option<Model> {
-    match unsafe { nitrokey_sys::NK_get_device_model() } {
-        nitrokey_sys::NK_device_model_NK_PRO => Some(Model::Pro),
-        nitrokey_sys::NK_device_model_NK_STORAGE => Some(Model::Storage),
-        _ => None,
-    }
+fn get_connected_model() -> Result<Model, Error> {
+    Model::try_from(unsafe { nitrokey_sys::NK_get_device_model() })
 }
 
 pub(crate) fn create_device_wrapper(
@@ -449,16 +540,40 @@ pub(crate) fn create_device_wrapper(
 pub(crate) fn get_connected_device(
     manager: &mut crate::Manager,
 ) -> Result<DeviceWrapper<'_>, Error> {
-    match get_connected_model() {
-        Some(model) => Ok(create_device_wrapper(manager, model)),
-        None => Err(CommunicationError::NotConnected.into()),
-    }
+    Ok(create_device_wrapper(manager, get_connected_model()?))
 }
 
 pub(crate) fn connect_enum(model: Model) -> bool {
-    let model = match model {
-        Model::Storage => nitrokey_sys::NK_device_model_NK_STORAGE,
-        Model::Pro => nitrokey_sys::NK_device_model_NK_PRO,
-    };
-    unsafe { nitrokey_sys::NK_login_enum(model) == 1 }
+    unsafe { nitrokey_sys::NK_login_enum(model.into()) == 1 }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::get_hidapi_serial_number;
+
+    #[test]
+    fn hidapi_serial_number() {
+        assert_eq!(None, get_hidapi_serial_number(""));
+        assert_eq!(None, get_hidapi_serial_number("00000000000000000"));
+        assert_eq!(
+            Some("00001234".to_string()),
+            get_hidapi_serial_number("1234")
+        );
+        assert_eq!(
+            Some("00001234".to_string()),
+            get_hidapi_serial_number("00001234")
+        );
+        assert_eq!(
+            Some("00001234".to_string()),
+            get_hidapi_serial_number("000000001234")
+        );
+        assert_eq!(
+            Some("100000001234".to_string()),
+            get_hidapi_serial_number("100000001234")
+        );
+        assert_eq!(
+            Some("10000001234".to_string()),
+            get_hidapi_serial_number("010000001234")
+        );
+    }
 }
diff --git a/src/error.rs b/src/error.rs
index 9e6adc0..f9af594 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -28,6 +28,8 @@ pub enum Error {
     UnexpectedError,
     /// An unknown error returned by libnitrokey.
     UnknownError(i64),
+    /// An error caused by a Nitrokey model that is not supported by this crate.
+    UnsupportedModelError,
     /// An error occurred when interpreting a UTF-8 string.
     Utf8Error(str::Utf8Error),
 }
@@ -102,6 +104,7 @@ impl error::Error for Error {
             Error::RandError(ref err) => Some(err.as_ref()),
             Error::UnexpectedError => None,
             Error::UnknownError(_) => None,
+            Error::UnsupportedModelError => None,
             Error::Utf8Error(ref err) => Some(err),
         }
     }
@@ -118,6 +121,7 @@ impl fmt::Display for Error {
             Error::RandError(ref err) => write!(f, "RNG error: {}", err),
             Error::UnexpectedError => write!(f, "An unexpected error occurred"),
             Error::UnknownError(ref err) => write!(f, "Unknown error: {}", err),
+            Error::UnsupportedModelError => write!(f, "Unsupported Nitrokey model"),
             Error::Utf8Error(ref err) => write!(f, "UTF-8 error: {}", err),
         }
     }
diff --git a/src/lib.rs b/src/lib.rs
index 059792d..7e8b3ef 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -16,6 +16,10 @@
 //! [`connect_model`][], [`connect_pro`][] or [`connect_storage`][] to connect to a specific
 //! device.
 //!
+//! To get a list of all connected Nitrokey devices, use the [`list_devices`][] function.  You can
+//! then connect to one of the connected devices using the [`connect_path`][] function of the
+//! `Manager` struct.
+//!
 //! You can call [`authenticate_user`][] or [`authenticate_admin`][] to get an authenticated device
 //! that can perform operations that require authentication.  You can use [`device`][] to go back
 //! to the unauthenticated device.
@@ -86,8 +90,10 @@
 //! [`take`]: fn.take.html
 //! [`connect`]: struct.Manager.html#method.connect
 //! [`connect_model`]: struct.Manager.html#method.connect_model
+//! [`connect_path`]: struct.Manager.html#method.connect_path
 //! [`connect_pro`]: struct.Manager.html#method.connect_pro
 //! [`connect_storage`]: struct.Manager.html#method.connect_storage
+//! [`list_devices`]: fn.list_devices.html
 //! [`manager`]: trait.Device.html#method.manager
 //! [`device`]: struct.User.html#method.device
 //! [`get_hotp_code`]: trait.GenerateOtp.html#method.get_hotp_code
@@ -109,8 +115,10 @@ 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;
@@ -118,14 +126,16 @@ use nitrokey_sys;
 pub use crate::auth::{Admin, Authenticate, User};
 pub use crate::config::Config;
 pub use crate::device::{
-    Device, DeviceWrapper, Model, Pro, SdCardData, Storage, StorageProductionInfo, StorageStatus,
-    VolumeMode, VolumeStatus,
+    Device, DeviceInfo, DeviceWrapper, Model, Pro, SdCardData, Storage, StorageProductionInfo,
+    StorageStatus, VolumeMode, VolumeStatus,
 };
 pub use crate::error::{CommandError, CommunicationError, Error, LibraryError};
 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_cstring, 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.
@@ -235,6 +245,7 @@ impl Manager {
     /// # Errors
     ///
     /// - [`NotConnected`][] if no Nitrokey device is connected
+    /// - [`UnsupportedModelError`][] if the Nitrokey device is not supported by this crate
     ///
     /// # Example
     ///
@@ -252,6 +263,7 @@ impl Manager {
     /// ```
     ///
     /// [`NotConnected`]: enum.CommunicationError.html#variant.NotConnected
+    /// [`UnsupportedModelError`]: enum.Error.html#variant.UnsupportedModelError
     pub fn connect(&mut self) -> Result<DeviceWrapper<'_>, Error> {
         if unsafe { nitrokey_sys::NK_login_auto() } == 1 {
             device::get_connected_device(self)
@@ -290,6 +302,49 @@ impl Manager {
         }
     }
 
+    /// Connects to a Nitrokey device at the given USB path.
+    ///
+    /// To get a list of all connected Nitrokey devices, use the [`list_devices`][] function.  The
+    /// [`DeviceInfo`][] structs returned by that function contain the USB path in the `path`
+    /// field.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if the USB path contains a null byte
+    /// - [`NotConnected`][] if no Nitrokey device can be found at the given USB path
+    /// - [`UnsupportedModelError`][] if the model of the Nitrokey device at the given USB path is
+    ///   not supported by this crate
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use nitrokey::DeviceWrapper;
+    ///
+    /// fn use_device(device: DeviceWrapper) {}
+    ///
+    /// let mut manager = nitrokey::take()?;
+    /// let devices = nitrokey::list_devices()?;
+    /// for device in devices {
+    ///     let device = manager.connect_path(device.path)?;
+    ///     use_device(device);
+    /// }
+    /// # Ok::<(), nitrokey::Error>(())
+    /// ```
+    ///
+    /// [`list_devices`]: fn.list_devices.html
+    /// [`DeviceInfo`]: struct.DeviceInfo.html
+    /// [`InvalidString`]: enum.LibraryError.html#variant.InvalidString
+    /// [`NotConnected`]: enum.CommunicationError.html#variant.NotConnected
+    /// [`UnsupportedModelError`]: enum.Error.html#variant.UnsupportedModelError
+    pub fn connect_path<S: Into<Vec<u8>>>(&mut self, path: S) -> Result<DeviceWrapper<'_>, Error> {
+        let path = get_cstring(path)?;
+        if unsafe { nitrokey_sys::NK_connect_with_path(path.as_ptr()) } == 1 {
+            device::get_connected_device(self)
+        } else {
+            Err(CommunicationError::NotConnected.into())
+        }
+    }
+
     /// Connects to a Nitrokey Pro.
     ///
     /// # Errors
@@ -414,6 +469,71 @@ 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.  To connect to a supported model, call the [`connect_path`][] function.
+///
+/// # 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>(())
+/// ```
+///
+/// [`connect_path`]: struct.Manager.html#fn.connect_path
+/// [`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..509763b 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());
 
@@ -78,17 +105,65 @@ fn assert_empty_serial_number() {
 }
 
 #[test_device]
+fn connect_path_no_device() {
+    let mut manager = unwrap_ok!(nitrokey::take());
+
+    assert_cmu_err!(CommunicationError::NotConnected, manager.connect_path(""));
+    assert_cmu_err!(
+        CommunicationError::NotConnected,
+        manager.connect_path("foobar")
+    );
+    // TODO: add realistic path
+}
+
+#[test_device]
+fn connect_path(device: DeviceWrapper) {
+    let manager = device.into_manager();
+
+    assert_cmu_err!(CommunicationError::NotConnected, manager.connect_path(""));
+    assert_cmu_err!(
+        CommunicationError::NotConnected,
+        manager.connect_path("foobar")
+    );
+    // TODO: add realistic path
+
+    let devices = unwrap_ok!(nitrokey::list_devices());
+    assert!(!devices.is_empty());
+    for device in devices {
+        let connected_device = unwrap_ok!(manager.connect_path(device.path));
+        assert_eq!(device.model, Some(connected_device.get_model()));
+        match device.model.unwrap() {
+            nitrokey::Model::Pro => {
+                assert!(device.serial_number.is_some());
+                assert_ok!(
+                    device.serial_number.unwrap(),
+                    connected_device.get_serial_number()
+                );
+            }
+            nitrokey::Model::Storage => {
+                assert_eq!(None, device.serial_number);
+            }
+        }
+    }
+}
+
+#[test_device]
 fn disconnect(device: DeviceWrapper) {
     drop(device);
     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());