Add windows portforward support

Signed-off-by: Angela Li <yanhuil@google.com>

pkg/server/sandbox_portforward.go

@@ -0,0 +1,38 @@
+/*
+Copyright The containerd 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 server
+
+import (
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+	runtime "k8s.io/cri-api/pkg/apis/runtime/v1alpha2"
+
+	sandboxstore "github.com/containerd/cri/pkg/store/sandbox"
+)
+
+// PortForward prepares a streaming endpoint to forward ports from a PodSandbox, and returns the address.
+func (c *criService) PortForward(ctx context.Context, r *runtime.PortForwardRequest) (retRes *runtime.PortForwardResponse, retErr error) {
+	sandbox, err := c.sandboxStore.Get(r.GetPodSandboxId())
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to find sandbox %q", r.GetPodSandboxId())
+	}
+	if sandbox.Status.Get().State != sandboxstore.StateReady {
+		return nil, errors.New("sandbox container is not running")
+	}
+	// TODO(random-liu): Verify that ports are exposed.
+	return c.streamServer.GetPortForward(r)
+}