Support reading OTP secrets from stdin

In an earlier commit we added support for reading PWS passwords from
stdin. With this patch, we use the same mechanism for OTP secrets.

CHANGELOG.md

@@ -7,7 +7,7 @@ Unreleased
 - Removed the `pws set` subcommand
 - Added the `--only-aes-key` option to the `reset` command to build a new AES
   key without performing a factory reset
-- Added support for reading PWS passwords from stdin
+- Added support for reading PWS passwords and OTP secrets from stdin
 - Added `NITROCLI_RESOLVED_USB_PATH` environment variable to be used by
   extensions
 - Allowed entering of `base32` encoded strings containing spaces

doc/nitrocli.1

@@ -1,4 +1,4 @@
-.TH NITROCLI 1 2021-04-20
+.TH NITROCLI 1 2021-04-24
 .SH NAME
 nitrocli \- access Nitrokey devices
 .SH SYNOPSIS
@@ -182,7 +182,7 @@ If \fB\-\-time\fR is set, it is set to \fItime\fR instead, which must be a Unix
 timestamp (i.e., the number of seconds since 1970-01-01 00:00:00 UTC).
 This command might require the user PIN (see the Configuration section).
 .TP
-\fBnitrocli otp set \fIslot name secret \
+\fBnitrocli otp set \fIslot name secret\fR|\fB-\fR \
 \fR[\fB\-a\fR|\fB\-\-algorithm \fIalgorithm\fR] \
 [\fB\-d\fR|\fB\-\-digits \fIdigits\fR] [\fB\-c\fR|\fB\-\-counter \fIcounter\fR] \
 [\fB\-t\fR|\fB\-\-time-window \fItime-window\fR] \
@@ -191,6 +191,8 @@ Configure a one-time password slot.
 \fIslot\fR is the number of the slot to configure.
 \fIname\fR is the name of the slot (may not be empty).
 \fIsecret\fR is the secret value to store in that slot.
+If \fIsecret\fR is set to \fB-\fR, the secret is read from the standard
+input.
 
 The \fB\-\-format\fR option specifies the format of the secret.
 If it is set to \fBascii\fR, each character of the given secret is interpreted

src/commands.rs

@@ -824,15 +824,18 @@ fn prepare_base32_secret(secret: &str) -> anyhow::Result<String> {
 }
 
 /// Prepare a secret string in the given format for libnitrokey.
-fn prepare_secret(secret: String, format: args::OtpSecretFormat) -> anyhow::Result<String> {
+fn prepare_secret(
+  secret: borrow::Cow<'_, str>,
+  format: args::OtpSecretFormat,
+) -> anyhow::Result<String> {
   match format {
     args::OtpSecretFormat::Ascii => prepare_ascii_secret(&secret),
     args::OtpSecretFormat::Base32 => prepare_base32_secret(&secret),
     args::OtpSecretFormat::Hex => {
       // We need to ensure to provide a string with an even number of
       // characters in it, just because that's what libnitrokey
       // expects. So prepend a '0' if that is not the case.
-      let mut secret = secret;
+      let mut secret = secret.into_owned();
       if secret.len() % 2 != 0 {
         secret.insert(0, '0')
       }
@@ -843,7 +846,8 @@ fn prepare_secret(secret: String, format: args::OtpSecretFormat) -> anyhow::Resu
 
 /// Configure a one-time password slot on the Nitrokey device.
 pub fn otp_set(ctx: &mut Context<'_>, args: args::OtpSetArgs) -> anyhow::Result<()> {
-  let secret = prepare_secret(args.secret, args.format)?;
+  let secret = value_or_stdin(ctx, &args.secret)?;
+  let secret = prepare_secret(secret, args.format)?;
   let data = nitrokey::OtpSlotData::new(args.slot, args.name, secret, args.digits.into());
   let (algorithm, counter, time_window) = (args.algorithm, args.counter, args.time_window);
   with_device(ctx, |ctx, device| {

src/tests/otp.rs

@@ -103,6 +103,24 @@ fn set_totp_uneven_chars(model: nitrokey::Model) -> anyhow::Result<()> {
   Ok(())
 }
 
+#[test_device]
+fn set_stdin(model: nitrokey::Model) -> anyhow::Result<()> {
+  const SECRET: &str = "12345678901234567890";
+  const TIME: &str = stringify!(1111111111);
+  const OTP: &str = concat!(14050471, "\n");
+
+  let _ = Nitrocli::new()
+    .model(model)
+    .stdin(SECRET)
+    .handle(&["otp", "set", "-d", "8", "-f", "ascii", "2", "name", "-"])?;
+
+  let out = Nitrocli::new()
+    .model(model)
+    .handle(&["otp", "get", "-t", TIME, "2"])?;
+  assert_eq!(out, OTP);
+  Ok(())
+}
+
 #[test_device]
 fn clear(model: nitrokey::Model) -> anyhow::Result<()> {
   let mut ncli = Nitrocli::new().model(model);