virtcontainers: Add a Network API skeleton for Darwin

Empty for now.

Fixes: #6051

Signed-off-by: Samuel Ortiz <s.ortiz@apple.com>
Signed-off-by: Eric Ernst <eric_ernst@apple.com>

src/runtime/virtcontainers/network_darwin.go

@@ -0,0 +1,101 @@
+// Copyright (c) 2023 Apple Inc.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package virtcontainers
+
+import (
+	"context"
+	"errors"
+
+	"github.com/vishvananda/netlink"
+
+	persistapi "github.com/kata-containers/kata-containers/src/runtime/virtcontainers/persist/api"
+)
+
+var endpointNotSupported error = errors.New("Unsupported endpoint on Darwin")
+
+// DarwinNetwork represents a sandbox networking setup.
+type DarwinNetwork struct {
+	networkID         string
+	interworkingModel NetInterworkingModel
+	networkCreated    bool
+	eps               []Endpoint
+}
+
+func NewNetwork(configs ...*NetworkConfig) (Network, error) {
+	if len(configs) > 1 {
+		return nil, errors.New("too many network configurations")
+	}
+
+	// Empty constructor
+	if len(configs) == 0 {
+		return &DarwinNetwork{}, nil
+	}
+
+	config := configs[0]
+	if config == nil {
+		return nil, errors.New("missing network configuration")
+	}
+
+	return &DarwinNetwork{
+		config.NetworkID,
+		config.InterworkingModel,
+		config.NetworkCreated,
+		[]Endpoint{},
+	}, nil
+}
+
+func LoadNetwork(netInfo persistapi.NetworkInfo) Network {
+	network := DarwinNetwork{
+		networkID:      netInfo.NetworkID,
+		networkCreated: netInfo.NetworkCreated,
+	}
+
+	return &network
+}
+
+func (n *DarwinNetwork) AddEndpoints(context.Context, *Sandbox, []NetworkInfo, bool) ([]Endpoint, error) {
+	return nil, endpointNotSupported
+}
+
+func (n *DarwinNetwork) RemoveEndpoints(context.Context, *Sandbox, []Endpoint, bool) error {
+	return endpointNotSupported
+}
+
+func (n *DarwinNetwork) Run(context.Context, func() error) error {
+	return nil
+}
+
+func (n *DarwinNetwork) NetworkID() string {
+	return n.networkID
+}
+
+func (n *DarwinNetwork) NetworkCreated() bool {
+	return n.networkCreated
+}
+
+func (n *DarwinNetwork) NetMonitorThread() int {
+	return 0
+}
+
+func (n *DarwinNetwork) SetNetMonitorThread(pid int) {
+	return
+}
+
+func (n *DarwinNetwork) Endpoints() []Endpoint {
+	return n.eps
+}
+
+func (n *DarwinNetwork) SetEndpoints(endpoints []Endpoint) {
+	n.eps = endpoints
+}
+
+func validGuestRoute(route netlink.Route) bool {
+	return true
+}
+
+func validGuestNeighbor(route netlink.Neigh) bool {
+	return true
+}