feat(sdk,ffi): add CheckCodeSender::validate()

bindings/matrix-sdk-ffi/CHANGELOG.md

@@ -8,6 +8,8 @@ All notable changes to this project will be documented in this file.
 
 ### Features
 
+- Add `CheckCodeSender::validate()` to allow `CheckCode` to be validated without sending.
+  ([#5957](https://github.com/matrix-org/matrix-rust-sdk/pull/5957))
 - Add `SpaceService::get_space_room` to get a space given its id from the space graph if available.
 [#5944](https://github.com/matrix-org/matrix-rust-sdk/pull/5944)
 - Add `QrCodeData::to_bytes()` to allow generation of a QR code.

bindings/matrix-sdk-ffi/src/qr_code.rs

@@ -633,4 +633,16 @@ impl CheckCodeSender {
     pub async fn send(&self, code: u8) -> Result<(), HumanQrLoginError> {
         self.inner.send(code).await.map_err(HumanQrLoginError::from)
     }
+
+    /// Validate the [`CheckCode`] without sending it.
+    ///
+    /// This can be used to provide immediate feedback to the user.
+    ///
+    /// # Arguments
+    /// * `check_code` - The check code in digits representation.
+    ///
+    /// Returns `true` if the code is valid, `false` otherwise.
+    pub fn validate(&self, check_code: u8) -> bool {
+        self.inner.validate(check_code)
+    }
 }

crates/matrix-sdk/CHANGELOG.md

@@ -8,6 +8,8 @@ All notable changes to this project will be documented in this file.
 
 ### Features
 
+- Add `CheckCodeSender::validate()` to allow `CheckCode` to be validated without sending.
+  ([#5957](https://github.com/matrix-org/matrix-rust-sdk/pull/5957))
 - Sending `MessageLike` and `RawMessageLike` events through a `Room` now returns
   the used `EncryptionInfo`, if any.
   ([#5936](https://github.com/matrix-org/matrix-rust-sdk/pull/5936))

crates/matrix-sdk/src/authentication/oauth/qrcode/grant.rs

@@ -346,7 +346,7 @@ impl<'a> IntoFuture for GrantLoginWithGeneratedQrCode<'a> {
             // -- MSC4108 Secure channel setup step 6
             let (tx, rx) = tokio::sync::oneshot::channel();
             self.state.set(GrantLoginProgress::EstablishingSecureChannel(
-                GeneratedQrProgress::QrScanned(CheckCodeSender::new(tx)),
+                GeneratedQrProgress::QrScanned(CheckCodeSender::new(tx, channel.check_code())),
             ));
             let check_code = rx.await.map_err(|_| SecureChannelError::CannotReceiveCheckCode)?;
 
@@ -756,6 +756,8 @@ mod test {
                             .expect("The checkcode should only be forwarded once")
                             .await
                             .expect("Alice should receive the checkcode");
+                        assert!(checkcode_sender.validate(checkcode));
+                        assert!(!checkcode_sender.validate((checkcode + 1) % 100));
                         checkcode_sender
                             .send(checkcode)
                             .await

crates/matrix-sdk/src/authentication/oauth/qrcode/login.rs

@@ -470,7 +470,7 @@ impl<'a> LoginWithGeneratedQrCode<'a> {
         trace!("Waiting for checkcode.");
         let (tx, rx) = tokio::sync::oneshot::channel();
         self.state.set(LoginProgress::EstablishingSecureChannel(GeneratedQrProgress::QrScanned(
-            CheckCodeSender::new(tx),
+            CheckCodeSender::new(tx, channel.check_code()),
         )));
 
         // Retrieve the entered checkcode and verify it to confirm that the channel is

crates/matrix-sdk/src/authentication/oauth/qrcode/mod.rs

@@ -329,11 +329,15 @@ pub enum GeneratedQrProgress {
 #[derive(Clone, Debug)]
 pub struct CheckCodeSender {
     inner: Arc<Mutex<Option<tokio::sync::oneshot::Sender<u8>>>>,
+    expected_check_code: CheckCode,
 }
 
 impl CheckCodeSender {
-    pub(crate) fn new(tx: tokio::sync::oneshot::Sender<u8>) -> Self {
-        Self { inner: Arc::new(Mutex::new(Some(tx))) }
+    pub(crate) fn new(
+        tx: tokio::sync::oneshot::Sender<u8>,
+        expected_check_code: CheckCode,
+    ) -> Self {
+        Self { inner: Arc::new(Mutex::new(Some(tx))), expected_check_code }
     }
 
     /// Send the checkcode.
@@ -349,6 +353,18 @@ impl CheckCodeSender {
             None => Err(CheckCodeSenderError::AlreadySent),
         }
     }
+
+    /// Validate the [`CheckCode`] without sending it.
+    ///
+    /// This can be used to provide immediate feedback to the user.
+    ///
+    /// # Arguments
+    /// * `check_code` - The check code in digits representation.
+    ///
+    /// Returns `true` if the code is valid, `false` otherwise.
+    pub fn validate(&self, check_code: u8) -> bool {
+        self.expected_check_code.to_digit() == check_code
+    }
 }
 
 /// Possible errors when calling [`CheckCodeSender::send`].

crates/matrix-sdk/src/authentication/oauth/qrcode/secure_channel/mod.rs

@@ -124,6 +124,10 @@ impl AlmostEstablishedSecureChannel {
             Err(Error::InvalidCheckCode)
         }
     }
+
+    pub fn check_code(&self) -> CheckCode {
+        self.secure_channel.check_code().clone()
+    }
 }
 
 pub(super) struct EstablishedSecureChannel {