Implement the pin set command

This change implements the pin set command which can be used to change
a Nitrokey's user or admin PIN.

5 files changed, 72 insertions, 3 deletions

diff --git a/nitrocli/README.md b/nitrocli/README.md
index ed5e4e4..ac6710f 100644
--- a/nitrocli/README.md
+++ b/nitrocli/README.md
@@ -15,8 +15,6 @@ The following commands are currently supported:
 - config: Access the Nitrokey's configuration
   - get: Read the current configuration.
   - set: Change the configuration.
-- pin: Change the Nitrokey’s PINs
-  - unblock: Unblock and reset the user PIN.
 - storage: Work with the Nitrokey's storage.
   - open: Open the encrypted volume. The user PIN needs to be entered.
   - close: Close the encrypted volume.
@@ -28,6 +26,7 @@ The following commands are currently supported:
   - clear: Delete an OTP slot.
 - pin: Manage the Nitrokey's PINs.
   - clear: Remove the user and admin PIN from gpg-agent's cache.
+  - set: Change the admin or the user PIN.
   - unblock: Unblock and reset the user PIN.
 
 ### *Note:*
diff --git a/nitrocli/doc/nitrocli.1 b/nitrocli/doc/nitrocli.1
index bec9a15..4e59352 100644
--- a/nitrocli/doc/nitrocli.1
+++ b/nitrocli/doc/nitrocli.1
@@ -139,6 +139,14 @@ Use the \fBstatus\fR command to check the retry counters.
 Clear the PINs cached by the other commands.
 
 .TP
+\fBnitrocli pin set \fItype\fR
+Change a PIN.
+\fItype\fR is the type of the PIN that will be changed:  \fBadmin\fR to change
+the admin PIN or \fBuser\fR to change the user PIN.
+This command only works if the retry counter for the PIN type is at least one.
+(Use the \fBstatus\fR command to check the retry counters.)
+
+.TP
 .B nitrocli pin unblock
 Unblock and reset the user PIN.
 This command requires the admin PIN.
diff --git a/nitrocli/src/args.rs b/nitrocli/src/args.rs
index 4341235..f00ac2a 100644
--- a/nitrocli/src/args.rs
+++ b/nitrocli/src/args.rs
@@ -24,6 +24,7 @@ use std::str;
 
 use crate::commands;
 use crate::error::Error;
+use crate::pinentry;
 
 type Result<T> = result::Result<T, Error>;
 
@@ -278,6 +279,7 @@ impl From<OtpMode> for nitrokey::OtpMode {
 #[derive(Debug)]
 enum PinCommand {
   Clear,
+  Set,
   Unblock,
 }
 
@@ -285,6 +287,7 @@ impl PinCommand {
   fn execute(&self, args: Vec<String>) -> Result<()> {
     match *self {
       PinCommand::Clear => pin_clear(args),
+      PinCommand::Set => pin_set(args),
       PinCommand::Unblock => pin_unblock(args),
     }
   }
@@ -297,6 +300,7 @@ impl fmt::Display for PinCommand {
       "{}",
       match *self {
         PinCommand::Clear => "clear",
+        PinCommand::Set => "set",
         PinCommand::Unblock => "unblock",
       }
     )
@@ -309,6 +313,7 @@ impl str::FromStr for PinCommand {
   fn from_str(s: &str) -> result::Result<Self, Self::Err> {
     match s {
       "clear" => Ok(PinCommand::Clear),
+      "set" => Ok(PinCommand::Set),
       "unblock" => Ok(PinCommand::Unblock),
       _ => Err(()),
     }
@@ -693,7 +698,7 @@ fn pin(args: Vec<String>) -> Result<()> {
   let _ = parser.refer(&mut subcommand).required().add_argument(
     "subcommand",
     argparse::Store,
-    "The subcommand to execute (clear|unblock)",
+    "The subcommand to execute (clear|set|unblock)",
   );
   let _ = parser.refer(&mut subargs).add_argument(
     "arguments",
@@ -717,6 +722,22 @@ fn pin_clear(args: Vec<String>) -> Result<()> {
   commands::pin_clear()
 }
 
+/// Change a PIN.
+fn pin_set(args: Vec<String>) -> Result<()> {
+  let mut pintype = pinentry::PinType::User;
+  let mut parser = argparse::ArgumentParser::new();
+  parser.set_description("Changes a PIN");
+  let _ = parser.refer(&mut pintype).required().add_argument(
+    "type",
+    argparse::Store,
+    "The PIN type to change (admin|user)",
+  );
+  parse(&parser, args)?;
+  drop(parser);
+
+  commands::pin_set(pintype)
+}
+
 /// Unblock and reset the user PIN.
 fn pin_unblock(args: Vec<String>) -> Result<()> {
   let mut parser = argparse::ArgumentParser::new();
diff --git a/nitrocli/src/commands.rs b/nitrocli/src/commands.rs
index e3e2a14..b018a58 100644
--- a/nitrocli/src/commands.rs
+++ b/nitrocli/src/commands.rs
@@ -507,6 +507,20 @@ fn choose_pin(pintype: pinentry::PinType) -> Result<String> {
   }
 }
 
+/// Change a PIN.
+pub fn pin_set(pintype: pinentry::PinType) -> Result<()> {
+  let device = get_device()?;
+  let new_pin = choose_pin(pintype)?;
+  try_with_passphrase(
+    pintype,
+    "Could not change the PIN",
+    |current_pin| match pintype {
+      pinentry::PinType::Admin => device.change_admin_pin(&current_pin, &new_pin),
+      pinentry::PinType::User => device.change_user_pin(&current_pin, &new_pin),
+    },
+  )
+}
+
 /// Unblock and reset the user PIN.
 pub fn pin_unblock() -> Result<()> {
   let device = get_device()?;
diff --git a/nitrocli/src/pinentry.rs b/nitrocli/src/pinentry.rs
index 33b5266..0d9fc5f 100644
--- a/nitrocli/src/pinentry.rs
+++ b/nitrocli/src/pinentry.rs
@@ -17,7 +17,9 @@
 // * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 // *************************************************************************
 
+use std::fmt;
 use std::process;
+use std::str;
 
 use crate::error::Error;
 
@@ -33,6 +35,31 @@ pub enum PinType {
   User,
 }
 
+impl fmt::Display for PinType {
+  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    write!(
+      f,
+      "{}",
+      match *self {
+        PinType::Admin => "admin",
+        PinType::User => "user",
+      }
+    )
+  }
+}
+
+impl str::FromStr for PinType {
+  type Err = ();
+
+  fn from_str(s: &str) -> Result<Self, Self::Err> {
+    match s {
+      "admin" => Ok(PinType::Admin),
+      "user" => Ok(PinType::User),
+      _ => Err(()),
+    }
+  }
+}
+
 impl PinType {
   fn cache_id(self) -> &'static str {
     match self {