Replace FIDO example with a dummy app

Maintaining a working setup for the FIDO and admin app is a lot of work
and is redundant to the usbip runner provided as part of the Nitrokey 3
firmware.  Therefore, this patch replaces the fido example with a much
simpler example that just setups up a dummy client responding to a
vendor command that requests random data.

This is sufficient for basic testing and getting started.  For more
advanced use cases, the Nitrokey 3 runner should be used.

Fixes: #31

Cargo.toml

@@ -24,26 +24,17 @@ clap = { version = "3.0.0", features = ["derive"] }
 clap-num = "1.0.0"
 delog = { version = "0.1.6", features = ["std-log"] }
 pretty_env_logger = "0.4.0"
-trussed = { version = "0.1", features = ["clients-3"] }
-
-# applications
-admin-app = { version = "0.1", features = ["log-all"] }
-fido-authenticator = { version = "0.1", features = ["dispatch", "log-all"] }
+trussed = { version = "0.1", features = ["clients-1"] }
 
 [features]
 default = ["ctaphid", "ccid"]
 ctaphid = ["ctaphid-dispatch", "usbd-ctaphid"]
 ccid = ["apdu-dispatch", "usbd-ccid"]
 
-[[example]]
-name = "fido"
-required-features = ["ctaphid"]
-
 [patch.crates-io]
 trussed = { git = "https://github.com/trussed-dev/trussed.git", rev = "51e68500d7601d04f884f5e95567d14b9018a6cb" }
 
 usbd-ctaphid = { git = "https://github.com/trussed-dev/usbd-ctaphid", rev = "e9cbf904f548979685c4c06d75479b75e3695160" }
 usbd-ccid = { git = "https://github.com/trussed-dev/usbd-ccid", tag = "0.3.0" }
 ctaphid-dispatch = { git = "https://github.com/trussed-dev/ctaphid-dispatch", rev = "57cb3317878a8593847595319aa03ef17c29ec5b" }
 apdu-dispatch = { git = "https://github.com/trussed-dev/apdu-dispatch.git", rev = "b72d5eb9f4d7a3f107a78a2f0e41f3c403f4c7a4" }
-

Makefile

@@ -1,4 +1,4 @@
-EXAMPLE_NAME := fido
+EXAMPLE_NAME := dummy
 
 all: | start-sim attach finish-message
 

README.md

@@ -1,16 +1,23 @@
-# USB/IP Simulation
+# trussed-usbip
 
-This runner allows using USB/IP as a means to simulate device connection
-to the OS, and should allow faster development of the embedded applications.
+This crate facilitates simulation of Trussed devices using USB/IP.
+It should only be used for development and testing.
 
 Remarks:
-- Extensible with CTAP apps: currently FIDO and Admin are active;
-- Does not work with Firefox at the moment;
-- Allows to inject own FIDO certificates, and device properties;
 - Requires multiple `usbip attach` calls to make it work [1].
+- Works best with CTAPHID.  CCID is supported but often unstable.
 
 [1] https://github.com/Sawchord/usbip-device#known-bugs
 
+## Examples
+
+[`examples/dummy.rs`](`examples/dummy.rs`) contains a very simple example that
+shows how to run a simulated Trussed device.
+For a more complex example, see the [usbip runner][] of the Nitrokey 3 that
+provides all features of the Nitrokey 3.
+
+[usbip runner]: https://github.com/Nitrokey/nitrokey-3-firmware/tree/main/runners/usbip
+
 ## Setup
 
 USB/IP tools are required to work, as well as kernel supporting it.

examples/dummy.rs

@@ -0,0 +1,139 @@
+//! USB/IP simulation of a Trussed device.
+//!
+//! This example contains a dummy app that responds with random data to the CTAPHID vendor command
+//! 0x60.  It can be tested with `nitropy nk3 list` and `nitropy nk3 rng`.
+//!
+//! For a more complete example, see the [usbip runner][] for the Nitrokey 3.
+//!
+//! [usbip runner]: https://github.com/Nitrokey/nitrokey-3-firmware/tree/main/runners/usbip
+
+use std::path::PathBuf;
+
+#[cfg(feature = "ccid")]
+use apdu_dispatch::command::SIZE as ApduCommandSize;
+#[cfg(feature = "ctaphid")]
+use ctaphid_dispatch::{
+    command::{Command, VendorCommand},
+    types::{AppResult, Error, Message},
+};
+
+use clap::Parser;
+use clap_num::maybe_hex;
+use trussed::{
+    backend::CoreOnly,
+    client::{Client, ClientBuilder},
+    service::Service,
+    syscall,
+    types::Vec,
+    virt::{self, Platform, StoreProvider},
+};
+use trussed_usbip::Syscall;
+
+/// USP/IP based virtualization a Trussed device.
+#[derive(Parser, Debug)]
+#[clap(about, version, author)]
+struct Args {
+    /// USB Name string
+    #[clap(short, long, default_value = "Trussed")]
+    name: String,
+
+    /// USB Manufacturer string
+    #[clap(short, long, default_value = "Trussed")]
+    manufacturer: String,
+
+    /// Trussed state file
+    #[clap(long, default_value = "trussed-state.bin")]
+    state_file: PathBuf,
+
+    /// USB VID id
+    #[clap(short, long, parse(try_from_str=maybe_hex), default_value_t = 0x20a0)]
+    vid: u16,
+
+    /// USB PID id
+    #[clap(short, long, parse(try_from_str=maybe_hex), default_value_t = 0x42b2)]
+    pid: u16,
+}
+
+struct DummyApp<C: Client> {
+    client: C,
+}
+
+impl<C: Client> DummyApp<C> {
+    fn rng<const N: usize>(&mut self, response: &mut Vec<u8, N>) {
+        let bytes = syscall!(self.client.random_bytes(57)).bytes;
+        response.extend_from_slice(&bytes).unwrap();
+    }
+}
+
+#[cfg(feature = "ctaphid")]
+const CTAPHID_COMMAND_RNG: Command = Command::Vendor(VendorCommand::H60);
+
+#[cfg(feature = "ctaphid")]
+impl<'a, C: Client> ctaphid_dispatch::app::App<'a> for DummyApp<C> {
+    fn commands(&self) -> &'static [Command] {
+        &[CTAPHID_COMMAND_RNG]
+    }
+
+    fn call(&mut self, command: Command, _request: &Message, response: &mut Message) -> AppResult {
+        match command {
+            CTAPHID_COMMAND_RNG => self.rng(response),
+            _ => return Err(Error::InvalidCommand),
+        }
+        Ok(())
+    }
+}
+
+struct Apps<C: Client> {
+    dummy: DummyApp<C>,
+}
+
+impl<'a, S: StoreProvider> trussed_usbip::Apps<'a, S, CoreOnly>
+    for Apps<trussed_usbip::Client<CoreOnly>>
+{
+    type Data = ();
+
+    fn new(service: &mut Service<Platform<S>, CoreOnly>, syscall: Syscall, _data: ()) -> Self {
+        let client = ClientBuilder::new("dummy")
+            .prepare(service)
+            .unwrap()
+            .build(syscall);
+        let dummy = DummyApp { client };
+        Self { dummy }
+    }
+
+    #[cfg(feature = "ctaphid")]
+    fn with_ctaphid_apps<T>(
+        &mut self,
+        f: impl FnOnce(&mut [&mut dyn ctaphid_dispatch::app::App<'a>]) -> T,
+    ) -> T {
+        f(&mut [&mut self.dummy])
+    }
+
+    #[cfg(feature = "ccid")]
+    fn with_ccid_apps<T>(
+        &mut self,
+        f: impl FnOnce(&mut [&mut dyn apdu_dispatch::app::App<ApduCommandSize, ApduCommandSize>]) -> T,
+    ) -> T {
+        f(&mut [])
+    }
+}
+
+fn main() {
+    pretty_env_logger::init();
+
+    let args = Args::parse();
+
+    let store = virt::Filesystem::new(args.state_file);
+    let options = trussed_usbip::Options {
+        manufacturer: Some(args.manufacturer),
+        product: Some(args.name),
+        serial_number: None,
+        vid: args.vid,
+        pid: args.pid,
+    };
+
+    log::info!("Initializing Trussed");
+    trussed_usbip::Builder::new(store, options)
+        .build::<Apps<_>>()
+        .exec(|_| ());
+}