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route_network.go
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/
route_network.go
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// +build !windows
// Copyright 2017 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 backend
import (
"bytes"
"net"
"sync"
"time"
log "github.com/golang/glog"
"golang.org/x/net/context"
"github.com/coreos/flannel/subnet"
"github.com/vishvananda/netlink"
)
const (
routeCheckRetries = 10
)
type RouteNetwork struct {
SimpleNetwork
BackendType string
routes []netlink.Route
SM subnet.Manager
GetRoute func(lease *subnet.Lease) *netlink.Route
Mtu int
LinkIndex int
}
func (n *RouteNetwork) MTU() int {
return n.Mtu
}
func (n *RouteNetwork) 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.SubnetLease, evts)
wg.Done()
}()
n.routes = make([]netlink.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 *RouteNetwork) handleSubnetEvents(batch []subnet.Event) {
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 != n.BackendType {
log.Warningf("Ignoring non-%v subnet: type=%v", n.BackendType, evt.Lease.Attrs.BackendType)
continue
}
route := n.GetRoute(&evt.Lease)
n.addToRouteList(*route)
// Check if route exists before attempting to add it
routeList, err := netlink.RouteListFiltered(netlink.FAMILY_V4, &netlink.Route{Dst: route.Dst}, netlink.RT_FILTER_DST)
if err != nil {
log.Warningf("Unable to list routes: %v", err)
}
if len(routeList) > 0 && !routeEqual(routeList[0], *route) {
// Same Dst different Gw or different link index. Remove it, correct route will be added below.
log.Warningf("Replacing existing route to %v via %v dev index %d with %v via %v dev index %d.", evt.Lease.Subnet, routeList[0].Gw, routeList[0].LinkIndex, evt.Lease.Subnet, evt.Lease.Attrs.PublicIP, route.LinkIndex)
if err := netlink.RouteDel(&routeList[0]); err != nil {
log.Errorf("Error deleting route to %v: %v", evt.Lease.Subnet, err)
continue
}
n.removeFromRouteList(routeList[0])
}
if len(routeList) > 0 && routeEqual(routeList[0], *route) {
// Same Dst and same Gw, keep it and do not attempt to add it.
log.Infof("Route to %v via %v dev index %d already exists, skipping.", evt.Lease.Subnet, evt.Lease.Attrs.PublicIP, routeList[0].LinkIndex)
} else if err := netlink.RouteAdd(route); err != nil {
log.Errorf("Error adding route to %v via %v dev index %d: %v", evt.Lease.Subnet, evt.Lease.Attrs.PublicIP, route.LinkIndex, err)
continue
}
case subnet.EventRemoved:
log.Info("Subnet removed: ", evt.Lease.Subnet)
if evt.Lease.Attrs.BackendType != n.BackendType {
log.Warningf("Ignoring non-%v subnet: type=%v", n.BackendType, evt.Lease.Attrs.BackendType)
continue
}
route := n.GetRoute(&evt.Lease)
// Always remove the route from the route list.
n.removeFromRouteList(*route)
if err := netlink.RouteDel(route); err != nil {
log.Errorf("Error deleting route to %v: %v", evt.Lease.Subnet, err)
continue
}
default:
log.Error("Internal error: unknown event type: ", int(evt.Type))
}
}
}
func (n *RouteNetwork) addToRouteList(route netlink.Route) {
for _, r := range n.routes {
if routeEqual(r, route) {
return
}
}
n.routes = append(n.routes, route)
}
func (n *RouteNetwork) removeFromRouteList(route netlink.Route) {
for index, r := range n.routes {
if routeEqual(r, route) {
n.routes = append(n.routes[:index], n.routes[index+1:]...)
return
}
}
}
func (n *RouteNetwork) routeCheck(ctx context.Context) {
for {
select {
case <-ctx.Done():
return
case <-time.After(routeCheckRetries * time.Second):
n.checkSubnetExistInRoutes()
}
}
}
func (n *RouteNetwork) checkSubnetExistInRoutes() {
routeList, err := netlink.RouteList(nil, netlink.FAMILY_V4)
if err == nil {
for _, route := range n.routes {
exist := false
for _, r := range routeList {
if r.Dst == nil {
continue
}
if routeEqual(r, route) {
exist = true
break
}
}
if !exist {
if err := netlink.RouteAdd(&route); err != nil {
if nerr, ok := err.(net.Error); !ok {
log.Errorf("Error recovering route to %v: %v, %v", route.Dst, route.Gw, nerr)
}
continue
} else {
log.Infof("Route recovered %v : %v", route.Dst, route.Gw)
}
}
}
} else {
log.Errorf("Error fetching route list. Will automatically retry: %v", err)
}
}
func routeEqual(x, y netlink.Route) bool {
// For ipip backend, when enabling directrouting, link index of some routes may change
// For both ipip and host-gw backend, link index may also change if updating ExtIface
if x.Dst.IP.Equal(y.Dst.IP) && x.Gw.Equal(y.Gw) && bytes.Equal(x.Dst.Mask, y.Dst.Mask) && x.LinkIndex == y.LinkIndex {
return true
}
return false
}