portforward: tunnel spdy through websockets

Kubernetes-commit: 8b447d8c97e8823b4308eb91cf7d75693e867c61

tools/portforward/fallback_dialer.go

@@ -0,0 +1,57 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License 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 portforward
+
+import (
+	"k8s.io/apimachinery/pkg/util/httpstream"
+	"k8s.io/klog/v2"
+)
+
+var _ httpstream.Dialer = &fallbackDialer{}
+
+// fallbackDialer encapsulates a primary and secondary dialer, including
+// the boolean function to determine if the primary dialer failed. Implements
+// the httpstream.Dialer interface.
+type fallbackDialer struct {
+	primary        httpstream.Dialer
+	secondary      httpstream.Dialer
+	shouldFallback func(error) bool
+}
+
+// NewFallbackDialer creates the fallbackDialer with the primary and secondary dialers,
+// as well as the boolean function to determine if the primary dialer failed.
+func NewFallbackDialer(primary, secondary httpstream.Dialer, shouldFallback func(error) bool) httpstream.Dialer {
+	return &fallbackDialer{
+		primary:        primary,
+		secondary:      secondary,
+		shouldFallback: shouldFallback,
+	}
+}
+
+// Dial is the single function necessary to implement the "httpstream.Dialer" interface.
+// It takes the protocol version strings to request, returning an the upgraded
+// httstream.Connection and the negotiated protocol version accepted. If the initial
+// primary dialer fails, this function attempts the secondary dialer. Returns an error
+// if one occurs.
+func (f *fallbackDialer) Dial(protocols ...string) (httpstream.Connection, string, error) {
+	conn, version, err := f.primary.Dial(protocols...)
+	if err != nil && f.shouldFallback(err) {
+		klog.V(4).Infof("fallback to secondary dialer from primary dialer err: %v", err)
+		return f.secondary.Dial(protocols...)
+	}
+	return conn, version, err
+}