Expose ssl_select_cert_disable_ech

boring/src/ssl/async_callbacks.rs

@@ -96,9 +96,16 @@ impl SslContextBuilder {
                 Poll::Pending => return Err(SelectCertError::RETRY),
             };
 
-            let finish = fut_result.or(Err(SelectCertError::ERROR))?;
-
-            finish(client_hello).or(Err(SelectCertError::ERROR))
+            let finish = fut_result.map_err(|e| match e {
+                AsyncSelectCertError::Error => SelectCertError::ERROR,
+                AsyncSelectCertError::DisableEch => SelectCertError::DISABLE_ECH,
+            })?;
+
+            match finish(client_hello) {
+                Ok(_) => Ok(()),
+                Err(AsyncSelectCertError::Error) => Err(SelectCertError::ERROR),
+                Err(AsyncSelectCertError::DisableEch) => Err(SelectCertError::DISABLE_ECH),
+            }
         });
     }
 
@@ -230,7 +237,12 @@ where
 
 /// A fatal error to be returned from async select certificate callbacks.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub struct AsyncSelectCertError;
+pub enum AsyncSelectCertError {
+    /// A fatal error occurred and the handshake should be terminated.
+    Error,
+    /// Discard ECH ClientHelloInner and re-handshake with ClientHelloOuter.
+    DisableEch,
+}
 
 /// Describes async private key hooks. This is used to off-load signing
 /// operations to a custom, potentially asynchronous, backend. Metadata about the

boring/src/ssl/mod.rs

@@ -563,6 +563,9 @@ impl SelectCertError {
 
     /// The operation could not be completed and should be retried later.
     pub const RETRY: Self = Self(ffi::ssl_select_cert_result_t::ssl_select_cert_retry);
+
+    /// Discard ECH ClientHelloInner and re-handshake with ClientHelloOuter.
+    pub const DISABLE_ECH: Self = Self(ffi::ssl_select_cert_result_t::ssl_select_cert_disable_ech);
 }
 
 /// Extension types, to be used with `ClientHello::get_extension`.

tokio-boring/tests/async_select_certificate.rs

@@ -35,13 +35,13 @@ async fn test_async_select_certificate_callback_yield() {
 
 #[tokio::test]
 async fn test_async_select_certificate_callback_return_error() {
-    with_async_select_certificate_callback_error(|_| Err(AsyncSelectCertError)).await;
+    with_async_select_certificate_callback_error(|_| Err(AsyncSelectCertError::Error)).await;
 }
 
 #[tokio::test]
 async fn test_async_select_certificate_callback_future_error() {
     with_async_select_certificate_callback_error(|_| {
-        Ok(Box::pin(async move { Err(AsyncSelectCertError) }))
+        Ok(Box::pin(async move { Err(AsyncSelectCertError::Error) }))
     })
     .await;
 }
@@ -52,7 +52,7 @@ async fn test_async_select_certificate_callback_future_yield_error() {
         Ok(Box::pin(async move {
             yield_now().await;
 
-            Err(AsyncSelectCertError)
+            Err(AsyncSelectCertError::Error)
         }))
     })
     .await;
@@ -64,7 +64,10 @@ async fn test_async_select_certificate_callback_finish_error() {
         Ok(Box::pin(async move {
             yield_now().await;
 
-            Ok(Box::new(|_: ClientHello<'_>| Err(AsyncSelectCertError)) as BoxSelectCertFinish)
+            Ok(
+                Box::new(|_: ClientHello<'_>| Err(AsyncSelectCertError::Error))
+                    as BoxSelectCertFinish,
+            )
         }))
     })
     .await;