Add support for password safes

A password safe (PWS) stores names, logins and passwords in slots.  PWS
are supported both by the Nitrokey Pro and the Nitrokey Storage.  They
are implemented as a struct wrapping a device as the device may not be
disconnected while the password safe is alive.  The creation of a
password safe is handled by the GetPasswordSafe trait, implemented by
DeviceWrapper, Pro and Storage.

1 files changed, 403 insertions, 0 deletions

diff --git a/src/pws.rs b/src/pws.rs
new file mode 100644
index 0000000..fc4b516
--- /dev/null
+++ b/src/pws.rs
@@ -0,0 +1,403 @@
+use device::{Device, DeviceWrapper, Pro, Storage};
+use libc;
+use nitrokey_sys;
+use std::ffi::CString;
+use util::{get_last_error, result_from_string, CommandError, CommandStatus};
+
+/// The number of slots in a [`PasswordSafe`][].
+///
+/// [`PasswordSafe`]: struct.PasswordSafe.html
+pub const SLOT_COUNT: u8 = 16;
+
+/// A password safe on a Nitrokey device.
+///
+/// The password safe stores a tuple consisting of a name, a login and a password on a slot.  The
+/// number of available slots is [`SLOT_COUNT`][].  The slots are addressed starting with zero.
+///
+/// The password safe struct wraps a device.  To get back to the original device, use the
+/// [`device`][] method.  To retrieve a password safe from a Nitrokey device, use the
+/// [`get_password_safe`][] method from the [`GetPasswordSafe`][] trait.
+///
+/// # Examples
+///
+/// Open a password safe and access a password:
+///
+/// ```no_run
+/// use nitrokey::{Device, GetPasswordSafe};
+/// # use nitrokey::CommandError;
+///
+/// fn use_device<T: Device>(device: &T) {}
+///
+/// # fn try_main() -> Result<(), CommandError> {
+/// let device = nitrokey::connect()?;
+/// let device = match device.get_password_safe("123456") {
+///     Ok(pws) => {
+///         let name = pws.get_slot_name(0)?;
+///         let login = pws.get_slot_login(0)?;
+///         let password = pws.get_slot_login(0)?;
+///         println!("Credentials for {}: login {}, password {}", name, login, password);
+///         pws.device()
+///     },
+///     Err((device, err)) => {
+///         println!("Could not open the password safe: {:?}", err);
+///         device
+///     },
+/// };
+/// use_device(&device);
+/// #     Ok(())
+/// # }
+/// ```
+///
+/// [`SLOT_COUNT`]: constant.SLOT_COUNT.html
+/// [`device`]: #method.device
+/// [`get_password_safe`]: trait.GetPasswordSafe.html#method.get_password_safe
+/// [`GetPasswordSafe`]: trait.GetPasswordSafe.html
+pub struct PasswordSafe<T: Device> {
+    device: T,
+}
+
+/// Provides access to a [`PasswordSafe`][].
+///
+/// When retrieving a password safe, the underlying device is consumed.  On success, the returned
+/// password safe also containes the device.  On error, the device is returned as part of the
+/// error.
+///
+/// [`PasswordSafe`]: struct.PasswordSafe.html
+pub trait GetPasswordSafe {
+    /// Enables and returns the password safe.  This method consumes the device.  You can go back
+    /// to the device using the [`device`][] method of the returned password safe.  If the method
+    /// fails, the current device will be returned as part of the error.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
+    /// - [`WrongPassword`][] if the current user password is wrong
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::{Device, GetPasswordSafe, PasswordSafe};
+    /// # use nitrokey::CommandError;
+    ///
+    /// fn use_password_safe<T: Device>(pws: &PasswordSafe<T>) {}
+    /// fn use_device<T: Device>(device: &T) {}
+    ///
+    /// # fn try_main() -> Result<(), CommandError> {
+    /// let device = nitrokey::connect()?;
+    /// let device = match device.get_password_safe("123456") {
+    ///     Ok(pws) => {
+    ///         use_password_safe(&pws);
+    ///         pws.device()
+    ///     },
+    ///     Err((device, err)) => {
+    ///         println!("Could not open the password safe: {:?}", err);
+    ///         device
+    ///     },
+    /// };
+    /// use_device(&device);
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`device`]: struct.PasswordSafe.html#method.device
+    /// [`InvalidString`]: enum.CommandError.html#variant.InvalidString
+    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
+    fn get_password_safe(self, user_pin: &str) -> Result<PasswordSafe<Self>, (Self, CommandError)>
+    where
+        Self: Device + Sized;
+}
+
+fn get_password_safe<T: Device>(
+    device: T,
+    user_pin: &str,
+) -> Result<PasswordSafe<T>, (T, CommandError)> {
+    let user_pin_string = CString::new(user_pin);
+    if user_pin_string.is_err() {
+        return Err((device, CommandError::InvalidString));
+    }
+    let user_pin_string = user_pin_string.unwrap();
+    let status = unsafe {
+        CommandStatus::from(nitrokey_sys::NK_enable_password_safe(
+            user_pin_string.as_ptr(),
+        ))
+    };
+    match status {
+        CommandStatus::Success => Ok(PasswordSafe { device }),
+        CommandStatus::Error(err) => Err((device, err)),
+    }
+}
+
+fn get_password_safe_wrapper<T, C>(
+    device: T,
+    constructor: C,
+    user_pin: &str,
+) -> Result<PasswordSafe<DeviceWrapper>, (DeviceWrapper, CommandError)>
+where
+    T: Device,
+    C: Fn(T) -> DeviceWrapper,
+{
+    let result = device.get_password_safe(user_pin);
+    match result {
+        Ok(pws) => Ok(PasswordSafe {
+            device: constructor(pws.device),
+        }),
+        Err((device, err)) => Err((constructor(device), err)),
+    }
+}
+
+impl<T: Device> PasswordSafe<T> {
+    /// Forgets the password safe access and returns an unauthenticated device.  This method
+    /// consumes the password safe.  It does not perform any actual commands on the Nitrokey.
+    pub fn device(self) -> T {
+        self.device
+    }
+
+    /// Returns the status of all password slots.
+    ///
+    /// The status indicates whether a slot is programmed or not.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::{GetPasswordSafe, SLOT_COUNT};
+    /// # use nitrokey::CommandError;
+    ///
+    /// # fn try_main() -> Result<(), CommandError> {
+    /// let device = nitrokey::connect()?;
+    /// match device.get_password_safe("123456") {
+    ///     Ok(pws) => {
+    ///         pws.get_slot_status()?.iter().enumerate().for_each(|(slot, programmed)| {
+    ///             let status = match *programmed {
+    ///                 true => "programmed",
+    ///                 false => "not programmed",
+    ///             };
+    ///             println!("Slot {}: {}", slot, status);
+    ///         });
+    ///     },
+    ///     Err((_, err)) => println!("Could not open the password safe: {:?}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    pub fn get_slot_status(&self) -> Result<[bool; SLOT_COUNT as usize], CommandError> {
+        let status_ptr = unsafe { nitrokey_sys::NK_get_password_safe_slot_status() };
+        if status_ptr.is_null() {
+            return Err(get_last_error());
+        }
+        let status_array_ptr = status_ptr as *const [u8; SLOT_COUNT as usize];
+        let status_array = unsafe { *status_array_ptr };
+        let mut result = [false; SLOT_COUNT as usize];
+        for i in 0..SLOT_COUNT {
+            result[i as usize] = status_array[i as usize] == 1;
+        }
+        unsafe {
+            libc::free(status_ptr as *mut libc::c_void);
+        }
+        Ok(result)
+    }
+
+    /// Returns the name of the given slot (if it is programmed).
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidSlot`][] if the given slot is out of range
+    /// - [`Unknown`][] if the slot is not programmed
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::GetPasswordSafe;
+    /// # use nitrokey::CommandError;
+    ///
+    /// # fn try_main() -> Result<(), CommandError> {
+    /// let device = nitrokey::connect()?;
+    /// match device.get_password_safe("123456") {
+    ///     Ok(pws) => {
+    ///         let name = pws.get_slot_name(0)?;
+    ///         let login = pws.get_slot_login(0)?;
+    ///         let password = pws.get_slot_login(0)?;
+    ///         println!("Credentials for {}: login {}, password {}", name, login, password);
+    ///     },
+    ///     Err((_, err)) => println!("Could not open the password safe: {:?}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidSlot`]: enum.CommandError.html#variant.InvalidSlot
+    /// [`Unknown`]: enum.CommandError.html#variant.Unknown
+    pub fn get_slot_name(&self, slot: u8) -> Result<String, CommandError> {
+        unsafe { result_from_string(nitrokey_sys::NK_get_password_safe_slot_name(slot)) }
+    }
+
+    /// Returns the login for the given slot (if it is programmed).
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidSlot`][] if the given slot is out of range
+    /// - [`Unknown`][] if the slot is not programmed
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::GetPasswordSafe;
+    /// # use nitrokey::CommandError;
+    ///
+    /// # fn try_main() -> Result<(), CommandError> {
+    /// let device = nitrokey::connect()?;
+    /// match device.get_password_safe("123456") {
+    ///     Ok(pws) => {
+    ///         let name = pws.get_slot_name(0)?;
+    ///         let login = pws.get_slot_login(0)?;
+    ///         let password = pws.get_slot_login(0)?;
+    ///         println!("Credentials for {}: login {}, password {}", name, login, password);
+    ///     },
+    ///     Err((_, err)) => println!("Could not open the password safe: {:?}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidSlot`]: enum.CommandError.html#variant.InvalidSlot
+    /// [`Unknown`]: enum.CommandError.html#variant.Unknown
+    pub fn get_slot_login(&self, slot: u8) -> Result<String, CommandError> {
+        unsafe { result_from_string(nitrokey_sys::NK_get_password_safe_slot_login(slot)) }
+    }
+
+    /// Returns the password for the given slot (if it is programmed).
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidSlot`][] if the given slot is out of range
+    /// - [`Unknown`][] if the slot is not programmed
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::GetPasswordSafe;
+    /// # use nitrokey::CommandError;
+    ///
+    /// # fn try_main() -> Result<(), CommandError> {
+    /// let device = nitrokey::connect()?;
+    /// match device.get_password_safe("123456") {
+    ///     Ok(pws) => {
+    ///         let name = pws.get_slot_name(0)?;
+    ///         let login = pws.get_slot_login(0)?;
+    ///         let password = pws.get_slot_login(0)?;
+    ///         println!("Credentials for {}: login {}, password {}", name, login, password);
+    ///     },
+    ///     Err((_, err)) => println!("Could not open the password safe: {:?}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidSlot`]: enum.CommandError.html#variant.InvalidSlot
+    /// [`Unknown`]: enum.CommandError.html#variant.Unknown
+    pub fn get_slot_password(&self, slot: u8) -> Result<String, CommandError> {
+        unsafe { result_from_string(nitrokey_sys::NK_get_password_safe_slot_password(slot)) }
+    }
+
+    /// Writes the given slot with the given name, login and password.
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidSlot`][] if the given slot is out of range
+    /// - [`InvalidString`][] if the provided token ID contains a null byte
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::{CommandStatus, GetPasswordSafe};
+    /// # use nitrokey::CommandError;
+    ///
+    /// # fn try_main() -> Result<(), CommandError> {
+    /// let device = nitrokey::connect()?;
+    /// match device.get_password_safe("123456") {
+    ///     Ok(pws) => match pws.write_slot(0, "GitHub", "johndoe", "passw0rd") {
+    ///         CommandStatus::Success => println!("Successfully wrote slot 0."),
+    ///         CommandStatus::Error(err) => println!("Could not write slot 0: {:?}", err),
+    ///     },
+    ///     Err((_, err)) => println!("Could not open the password safe: {:?}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidSlot`]: enum.CommandError.html#variant.InvalidSlot
+    /// [`InvalidString`]: enum.CommandError.html#variant.InvalidString
+    pub fn write_slot(&self, slot: u8, name: &str, login: &str, password: &str) -> CommandStatus {
+        let name_string = CString::new(name);
+        let login_string = CString::new(login);
+        let password_string = CString::new(password);
+        if name_string.is_err() || login_string.is_err() || password_string.is_err() {
+            return CommandStatus::Error(CommandError::InvalidString);
+        }
+
+        let name_string = name_string.unwrap();
+        let login_string = login_string.unwrap();
+        let password_string = password_string.unwrap();
+        unsafe {
+            CommandStatus::from(nitrokey_sys::NK_write_password_safe_slot(
+                slot,
+                name_string.as_ptr(),
+                login_string.as_ptr(),
+                password_string.as_ptr(),
+            ))
+        }
+    }
+
+    /// Erases the given slot.  Erasing clears the stored name, login and password (if the slot was
+    /// programmed).
+    ///
+    /// # Errors
+    ///
+    /// - [`InvalidSlot`][] if the given slot is out of range
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// use nitrokey::{CommandStatus, GetPasswordSafe};
+    /// # use nitrokey::CommandError;
+    ///
+    /// # fn try_main() -> Result<(), CommandError> {
+    /// let device = nitrokey::connect()?;
+    /// match device.get_password_safe("123456") {
+    ///     Ok(pws) => match pws.erase_slot(0) {
+    ///         CommandStatus::Success => println!("Successfully erased slot 0."),
+    ///         CommandStatus::Error(err) => println!("Could not erase slot 0: {:?}", err),
+    ///     },
+    ///     Err((_, err)) => println!("Could not open the password safe: {:?}", err),
+    /// };
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`InvalidSlot`]: enum.CommandError.html#variant.InvalidSlot
+    pub fn erase_slot(&self, slot: u8) -> CommandStatus {
+        unsafe { CommandStatus::from(nitrokey_sys::NK_erase_password_safe_slot(slot)) }
+    }
+}
+
+impl GetPasswordSafe for Pro {
+    fn get_password_safe(self, user_pin: &str) -> Result<PasswordSafe<Self>, (Self, CommandError)> {
+        get_password_safe(self, user_pin)
+    }
+}
+
+impl GetPasswordSafe for Storage {
+    fn get_password_safe(self, user_pin: &str) -> Result<PasswordSafe<Self>, (Self, CommandError)> {
+        get_password_safe(self, user_pin)
+    }
+}
+
+impl GetPasswordSafe for DeviceWrapper {
+    fn get_password_safe(self, user_pin: &str) -> Result<PasswordSafe<Self>, (Self, CommandError)> {
+        match self {
+            DeviceWrapper::Storage(storage) => {
+                get_password_safe_wrapper(storage, DeviceWrapper::Storage, user_pin)
+            }
+            DeviceWrapper::Pro(pro) => get_password_safe_wrapper(pro, DeviceWrapper::Pro, user_pin),
+        }
+    }
+}