isTemporaryNetErr didn't work when the error was wrapped

Signed-off-by: Kazuyoshi Kato <[email protected]>

Author: kzys

internal/vm/vsock.go

@@ -314,9 +314,9 @@ func (e vsockAckError) Temporary() bool {
 // error, according to the interface defined here:
 // https://golang.org/pkg/net/#Error
 func isTemporaryNetErr(err error) bool {
-	terr, ok := err.(interface {
+	type tempError interface {
 		Temporary() bool
-	})
-
-	return err != nil && ok && terr.Temporary()
+	}
+	var terr tempError
+	return err != nil && errors.As(err, &terr) && terr.Temporary()
 }

internal/vm/vsock_test.go

@@ -0,0 +1,27 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"). You may
+// not use this file except in compliance with the License. A copy of the
+// License is located at
+//
+//	http://aws.amazon.com/apache2.0/
+//
+// or in the "license" file accompanying this file. This file is distributed
+// on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied. See the License for the specific language governing
+// permissions and limitations under the License.
+
+package vm
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTemporaryNetErr(t *testing.T) {
+	assert.False(t, isTemporaryNetErr(nil))
+	assert.False(t, isTemporaryNetErr(errors.New("hello")))
+	assert.True(t, isTemporaryNetErr(&vsockAckError{cause: errors.New("hello")}))
+}