From eda9b76c36aef006facbfcf8c6da05b3cae72809 Mon Sep 17 00:00:00 2001
From: Robin Krahl <robin@nitrokey.com>
Date: Mon, 19 Feb 2024 20:48:46 +0100
Subject: [PATCH] Support invalid CTAPHID commands

Previously, we just ignored invalid CTAPHID commands.  With this patch,
we return a CTAPHID_INVALID_COMMAND error.
---
 src/pipe.rs | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/pipe.rs b/src/pipe.rs
index f81dfa1..998e609 100644
--- a/src/pipe.rs
+++ b/src/pipe.rs
@@ -70,8 +70,12 @@ impl Response {
     }
 
     pub fn error_from_request(request: Request) -> Self {
+        Self::error_on_channel(request.channel)
+    }
+
+    pub fn error_on_channel(channel: u32) -> Self {
         Self {
-            channel: request.channel,
+            channel,
             command: ctaphid_dispatch::command::Command::Error,
             length: 1,
         }
@@ -292,7 +296,8 @@ impl<'alloc, 'pipe, 'interrupt, Bus: UsbBus> Pipe<'alloc, 'pipe, 'interrupt, Bus
                 Ok(command) => command,
                 // `solo ls` crashes here as it uses command 0x86
                 Err(_) => {
-                    info!("Ignoring invalid command.");
+                    info!("Received invalid command.");
+                    self.start_sending_error_on_channel(channel, AuthenticatorError::InvalidCommand);
                     return;
                 }
             };
@@ -616,8 +621,12 @@ impl<'alloc, 'pipe, 'interrupt, Bus: UsbBus> Pipe<'alloc, 'pipe, 'interrupt, Bus
     }
 
     fn start_sending_error(&mut self, request: Request, error: AuthenticatorError) {
+        self.start_sending_error_on_channel(request.channel, error);
+    }
+
+    fn start_sending_error_on_channel(&mut self, channel: u32, error: AuthenticatorError) {
         self.buffer[0] = error as u8;
-        let response = Response::error_from_request(request);
+        let response = Response::error_on_channel(channel);
         self.start_sending(response);
     }