Add command to list configuration options

Cargo.toml

@@ -11,7 +11,7 @@ description = "Administrative Trussed app for SoloKeys Solo 2 security keys"
 
 [dependencies]
 apdu-dispatch = "0.1"
-cbor-smol = "0.4.0"
+cbor-smol = { version = "0.4.0", features = ["heapless-v0-7", "heapless-bytes-v0-3"] }
 ctaphid-dispatch = "0.1"
 delog = "0.1"
 iso7816 = "0.1"
@@ -48,3 +48,4 @@ littlefs2 = { git = "https://github.com/trussed-dev/littlefs2.git", rev = "ebd27
 trussed = { git = "https://github.com/Nitrokey/trussed.git", tag = "v0.1.0-nitrokey.18" }
 trussed-manage = { git = "https://github.com/trussed-dev/trussed-staging.git", tag = "manage-v0.1.0" }
 trussed-se050-manage = { git = "https://github.com/Nitrokey/trussed-se050-backend.git", tag = "se050-manage-v0.1.0" }
+cbor-smol = { git = "https://github.com/trussed-dev/cbor-smol.git", rev = "4a368461e06e3ca52d79638b9ab8f34b038491fc" }

src/admin.rs

@@ -1,7 +1,7 @@
 use super::Client as TrussedClient;
 use apdu_dispatch::iso7816::Status;
 use apdu_dispatch::{app as apdu, command, dispatch::Interface, response, Command as ApduCommand};
-use cbor_smol::cbor_deserialize;
+use cbor_smol::{cbor_deserialize, cbor_serialize_to};
 use core::{convert::TryInto, marker::PhantomData, time::Duration};
 use ctaphid_dispatch::app::{self as hid, Command as HidCommand, Message};
 use ctaphid_dispatch::command::VendorCommand;
@@ -28,6 +28,7 @@ const SET_CONFIG: u8 = 0x83;
 const FACTORY_RESET: u8 = 0x84;
 #[cfg(feature = "factory-reset")]
 const FACTORY_RESET_APP: u8 = 0x85;
+const LIST_AVAILABLE_FIELDS: u8 = 0x86;
 
 // For compatibility, old commands are also available directly as separate vendor commands.
 const UPDATE: VendorCommand = VendorCommand::H51;
@@ -69,6 +70,7 @@ enum Command {
     FactoryReset,
     #[cfg(feature = "factory-reset")]
     FactoryResetApp,
+    ListAvailableFields,
 }
 
 impl TryFrom<u8> for Command {
@@ -92,6 +94,7 @@ impl TryFrom<u8> for Command {
             FACTORY_RESET => Ok(Command::FactoryReset),
             #[cfg(feature = "factory-reset")]
             FACTORY_RESET_APP => Ok(Command::FactoryResetApp),
+            LIST_AVAILABLE_FIELDS => Ok(Command::ListAvailableFields),
             _ => Err(Error::UnsupportedCommand),
         }
     }
@@ -426,6 +429,10 @@ where
                 };
                 response.push(status).ok();
             }
+            Command::ListAvailableFields => {
+                cbor_serialize_to(&self.config.list_available_fields(), response).ok();
+                return Ok(());
+            }
             #[cfg(feature = "factory-reset")]
             Command::FactoryReset => {
                 debug_now!("Factory resetting the device");

src/config.rs

@@ -20,7 +20,7 @@ use trussed::{
 ///
 /// It is expected to have one such structure for each application supporting factory-reset by the admin-app
 ///
-/// ```rust
+/// ```rust,ignore
 ///# use admin_app::{ResetSignalAllocation, ConfigValueMut};
 ///# use littlefs2::{path::Path, path};
 /// #[derive(Default, PartialEq, serde::Deserialize, serde::Serialize)]
@@ -163,6 +163,34 @@ pub trait Config: Default + PartialEq + DeserializeOwned + Serialize {
     ///
     /// Return false if the configuration does not support storing the migration version
     fn set_migration_version(&mut self, _version: u32) -> bool;
+
+    fn list_available_fields(&self) -> &'static [ConfigField];
+}
+
+// No need to rename, cbor-smol already packs enum using ids
+#[derive(Serialize)]
+#[non_exhaustive]
+pub enum FieldType {
+    Bool,
+    U8,
+}
+
+#[derive(Serialize)]
+pub struct ConfigField {
+    #[serde(rename = "n")]
+    pub name: &'static str,
+    /// Changing the config field requires a touch
+    #[serde(rename = "c")]
+    pub requires_touch_confirmation: bool,
+    /// Changing the config field requires a power cycle
+    #[serde(rename = "r")]
+    pub requires_reboot: bool,
+    /// Changing the config field deletes data
+    #[serde(rename = "d")]
+    pub destructive: bool,
+    /// The type of data stored in this field
+    #[serde(rename = "t")]
+    pub ty: FieldType,
 }
 
 impl Config for () {
@@ -181,6 +209,10 @@ impl Config for () {
     fn set_migration_version(&mut self, _version: u32) -> bool {
         false
     }
+
+    fn list_available_fields(&self) -> &'static [ConfigField] {
+        &[]
+    }
 }
 
 #[derive(Debug, Serialize)]
@@ -313,3 +345,27 @@ fn load_if_exists<F: Filestore>(
         }
     })
 }
+
+#[cfg(test)]
+mod tests {
+    use hex_literal::hex;
+
+    use super::*;
+
+    #[test]
+    fn config_field() {
+        let fields = &[ConfigField {
+            name: "test_name",
+            requires_touch_confirmation: true,
+            requires_reboot: false,
+            destructive: true,
+            ty: FieldType::Bool,
+        }];
+        let mut bytes: trussed::types::Vec<u8, 100> = Default::default();
+        cbor_smol::cbor_serialize_to(fields, &mut bytes).unwrap();
+        assert_eq!(
+            &bytes,
+            &hex!("81A5616E69746573745F6E616D656163F56172F46164F5617400")
+        );
+    }
+}

src/lib.rs

@@ -16,7 +16,8 @@ pub mod migrations;
 
 pub use admin::{App, Reboot, StatusBytes};
 pub use config::{
-    Config, ConfigError, ConfigValueMut, ResetConfigResult, ResetSignal, ResetSignalAllocation,
+    Config, ConfigError, ConfigField, ConfigValueMut, FieldType, ResetConfigResult, ResetSignal,
+    ResetSignalAllocation,
 };
 use trussed_manage::ManageClient;
 #[cfg(feature = "se050")]