Implement the otp get subcommand

This patch implements the `otp get` subcommand that allows the user to
generate a one-time password on the Nitrokey device.  Before generating
the password, the device configuration is checked so that the user only
has to enter a PIN if it is required for the OTP generation.

1 files changed, 31 insertions, 1 deletions

diff --git a/nitrocli/src/commands.rs b/nitrocli/src/commands.rs
index 9761728..a82734e 100644
--- a/nitrocli/src/commands.rs
+++ b/nitrocli/src/commands.rs
@@ -20,7 +20,9 @@
 use std::result;
 
 use nitrokey::Device;
+use nitrokey::GenerateOtp;
 
+use crate::args;
 use crate::error::Error;
 use crate::pinentry;
 use crate::Result;
@@ -30,6 +32,11 @@ fn get_error(msg: &str, err: &nitrokey::CommandError) -> Error {
   Error::Error(format!("{}: {:?}", msg, err))
 }
 
+/// Connect to any Nitrokey device and return it.
+fn get_device() -> Result<nitrokey::DeviceWrapper> {
+  nitrokey::connect().map_err(|_| Error::Error("Nitrokey device not found".to_string()))
+}
+
 /// Connect to a Nitrokey Storage device and return it.
 fn get_storage_device() -> Result<nitrokey::Storage> {
   nitrokey::Storage::connect()
@@ -53,7 +60,6 @@ where
 }
 
 /// Authenticate the given device with the user PIN.
-#[allow(unused)]
 fn authenticate_user<T>(device: T) -> Result<nitrokey::User<T>>
 where
   T: Device,
@@ -246,3 +252,27 @@ pub fn clear() -> Result<()> {
   pinentry::clear_passphrase(pinentry::PinType::User)?;
   Ok(())
 }
+
+fn get_otp<T: GenerateOtp>(slot: u8, algorithm: args::OtpAlgorithm, device: &T) -> Result<String> {
+  match algorithm {
+    args::OtpAlgorithm::Hotp => device.get_hotp_code(slot),
+    args::OtpAlgorithm::Totp => device.get_totp_code(slot),
+  }
+  .map_err(|err| get_error("Could not generate OTP", &err))
+}
+
+/// Generate a one-time password on the Nitrokey device.
+pub fn otp_get(slot: u8, algorithm: args::OtpAlgorithm) -> Result<()> {
+  let device = get_device()?;
+  let config = device
+    .get_config()
+    .map_err(|err| get_error("Could not get device configuration", &err))?;
+  let otp = if config.user_password {
+    let user = authenticate_user(device)?;
+    get_otp(slot, algorithm, &user)
+  } else {
+    get_otp(slot, algorithm, &device)
+  }?;
+  println!("{}", otp);
+  Ok(())
+}