feat(bindings): enable application owned certs (#4937)

bindings/rust/s2n-tls/src/callbacks/pkey.rs

@@ -128,7 +128,7 @@ mod tests {
         testing::{self, *},
     };
     use core::task::{Poll, Waker};
-    use futures_test::task::new_count_waker;
+    use futures_test::task::{new_count_waker, noop_waker};
     use openssl::{ec::EcKey, ecdsa::EcdsaSig};
 
     type Error = Box<dyn std::error::Error>;
@@ -350,4 +350,52 @@ mod tests {
         assert_test_error(err, ERROR);
         Ok(())
     }
+
+    /// pkey offload should also work with public certs created from
+    /// [CertificateChain::from_public_pems].
+    #[test]
+    fn app_owned_public_cert() -> Result<(), Error> {
+        struct TestPkeyCallback;
+        impl PrivateKeyCallback for TestPkeyCallback {
+            fn handle_operation(
+                &self,
+                conn: &mut connection::Connection,
+                op: PrivateKeyOperation,
+            ) -> Result<Option<Pin<Box<dyn ConnectionFuture>>>, error::Error> {
+                ecdsa_sign(op, conn, KEY)?;
+                Ok(None)
+            }
+        }
+
+        let public_chain = {
+            let mut chain = crate::cert_chain::Builder::new()?;
+            chain.load_public_pem(CERT)?;
+            chain.build()?
+        };
+
+        let server_config = {
+            let mut config = config::Builder::new();
+            config
+                .set_security_policy(&security::DEFAULT_TLS13)?
+                .load_chain(public_chain)?
+                .set_private_key_callback(TestPkeyCallback)?;
+            config.build()?
+        };
+
+        let client_config = {
+            let mut config = config::Builder::new();
+            config
+                .set_security_policy(&security::DEFAULT_TLS13)?
+                .set_verify_host_callback(InsecureAcceptAllCertificatesHandler {})?
+                .trust_pem(CERT)?;
+            config.build()?
+        };
+
+        let mut pair = TestPair::from_configs(&client_config, &server_config);
+        pair.server.set_waker(Some(&noop_waker()))?;
+
+        assert!(pair.handshake().is_ok());
+
+        Ok(())
+    }
 }