backend: Support host-gw backed on Windows

This uses new Windows Host Networking Service (HNS) features to
configure networking for the host-gw mode

Fixes #833

backend/hostgw/hostgw_network_windows.go

@@ -0,0 +1,208 @@
+// +build windows
+
+// Copyright 2015 flannel 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 hostgw
+
+import (
+	"sync"
+	"time"
+
+	log "github.com/golang/glog"
+	"golang.org/x/net/context"
+
+	"github.com/coreos/flannel/backend"
+	"github.com/coreos/flannel/subnet"
+
+	netroute "github.com/rakelkar/gonetsh/netroute"
+)
+
+type network struct {
+	name      string
+	extIface  *backend.ExternalInterface
+	linkIndex int
+	rl        []netroute.Route
+	lease     *subnet.Lease
+	sm        subnet.Manager
+}
+
+func (n *network) Lease() *subnet.Lease {
+	return n.lease
+}
+
+func (n *network) MTU() int {
+	return n.extIface.Iface.MTU
+}
+
+func (n *network) Run(ctx context.Context) {
+	wg := sync.WaitGroup{}
+
+	log.Info("Watching for new subnet leases")
+	evts := make(chan []subnet.Event)
+	wg.Add(1)
+	go func() {
+		subnet.WatchLeases(ctx, n.sm, n.lease, evts)
+		wg.Done()
+	}()
+
+	n.rl = make([]netroute.Route, 0, 10)
+	wg.Add(1)
+	go func() {
+		n.routeCheck(ctx)
+		wg.Done()
+	}()
+
+	defer wg.Wait()
+
+	for {
+		select {
+		case evtBatch := <-evts:
+			n.handleSubnetEvents(evtBatch)
+
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+func (n *network) handleSubnetEvents(batch []subnet.Event) {
+	nr := netroute.New()
+	defer nr.Exit()
+
+	for _, evt := range batch {
+		switch evt.Type {
+		case subnet.EventAdded:
+			log.Infof("Subnet added: %v via %v", evt.Lease.Subnet, evt.Lease.Attrs.PublicIP)
+
+			if evt.Lease.Attrs.BackendType != "host-gw" {
+				log.Warningf("Ignoring non-host-gw subnet: type=%v", evt.Lease.Attrs.BackendType)
+				continue
+			}
+
+			route := netroute.Route{
+				DestinationSubnet: evt.Lease.Subnet.ToIPNet(),
+				GatewayAddress:    evt.Lease.Attrs.PublicIP.ToIP(),
+				LinkIndex:         n.linkIndex,
+			}
+
+			existingRoutes, _ := nr.GetNetRoutes(route.LinkIndex, route.DestinationSubnet)
+
+			if existingRoutes != nil && len(existingRoutes) > 0 {
+				if existingRoutes[0].Equal(route) {
+					continue
+				}
+
+				log.Warningf("Replacing existing route to %v via %v with %v via %v.", evt.Lease.Subnet, existingRoutes[0].GatewayAddress, evt.Lease.Subnet, evt.Lease.Attrs.PublicIP)
+				err := nr.RemoveNetRoute(route.LinkIndex, route.DestinationSubnet, existingRoutes[0].GatewayAddress)
+				if err != nil {
+					log.Errorf("Error removing route: %v", err)
+					continue
+				}
+			}
+
+			err := nr.NewNetRoute(route.LinkIndex, route.DestinationSubnet, route.GatewayAddress)
+			if err != nil {
+				log.Errorf("Error creating route: %v", err)
+			}
+
+			n.addToRouteList(route)
+
+		case subnet.EventRemoved:
+			log.Info("Subnet removed: ", evt.Lease.Subnet)
+
+			if evt.Lease.Attrs.BackendType != "host-gw" {
+				log.Warningf("Ignoring non-host-gw subnet: type=%v", evt.Lease.Attrs.BackendType)
+				continue
+			}
+
+			route := netroute.Route{
+				DestinationSubnet: evt.Lease.Subnet.ToIPNet(),
+				GatewayAddress:    evt.Lease.Attrs.PublicIP.ToIP(),
+				LinkIndex:         n.linkIndex,
+			}
+
+			existingRoutes, _ := nr.GetNetRoutes(route.LinkIndex, route.DestinationSubnet)
+
+			if existingRoutes != nil {
+				err := nr.RemoveNetRoute(route.LinkIndex, route.DestinationSubnet, route.GatewayAddress)
+				if err != nil {
+					log.Errorf("Error removing route: %v", err)
+				}
+			}
+
+			n.removeFromRouteList(route)
+
+		default:
+			log.Error("Internal error: unknown event type: ", int(evt.Type))
+		}
+	}
+}
+
+func (n *network) addToRouteList(route netroute.Route) {
+	for _, r := range n.rl {
+		if r.Equal(route) {
+			return
+		}
+	}
+	n.rl = append(n.rl, route)
+}
+
+func (n *network) removeFromRouteList(route netroute.Route) {
+	for index, r := range n.rl {
+		if r.Equal(route) {
+			n.rl = append(n.rl[:index], n.rl[index+1:]...)
+			return
+		}
+	}
+}
+
+func (n *network) routeCheck(ctx context.Context) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-time.After(routeCheckRetries * time.Second):
+			n.checkSubnetExistInRoutes()
+		}
+	}
+}
+
+func (n *network) checkSubnetExistInRoutes() {
+	nr := netroute.New()
+	defer nr.Exit()
+
+	currentRoutes, err := nr.GetNetRoutesAll()
+	if err != nil {
+		log.Errorf("Error enumerating routes", err)
+		return
+	}
+	for _, r := range n.rl {
+		exist := false
+		for _, currentRoute := range currentRoutes {
+			if r.Equal(currentRoute) {
+				exist = true
+				break
+			}
+		}
+
+		if !exist {
+			err := nr.NewNetRoute(r.LinkIndex, r.DestinationSubnet, r.GatewayAddress)
+			if err != nil {
+				log.Errorf("Error recovering route to %v via %v on %v (%v).", r.DestinationSubnet, r.GatewayAddress, r.LinkIndex, err)
+				continue
+			}
+			log.Errorf("Recovered route to %v via %v on %v.", r.DestinationSubnet, r.GatewayAddress, r.LinkIndex)
+		}
+	}
+}