forked from flannel-io/flannel
/
udp_network_amd64.go
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/
udp_network_amd64.go
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// +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.
// +build !windows
package udp
import (
"fmt"
"net"
"os"
"sync"
"syscall"
log "github.com/golang/glog"
"github.com/vishvananda/netlink"
"golang.org/x/net/context"
"github.com/coreos/flannel/backend"
"github.com/coreos/flannel/pkg/ip"
"github.com/coreos/flannel/subnet"
)
const (
encapOverhead = 28 // 20 bytes IP hdr + 8 bytes UDP hdr
)
type network struct {
backend.SimpleNetwork
name string
port int
ctl *os.File
ctl2 *os.File
tun *os.File
conn *net.UDPConn
tunNet ip.IP4Net
sm subnet.Manager
}
func newNetwork(sm subnet.Manager, extIface *backend.ExternalInterface, port int, nw ip.IP4Net, l *subnet.Lease) (*network, error) {
n := &network{
SimpleNetwork: backend.SimpleNetwork{
SubnetLease: l,
ExtIface: extIface,
},
port: port,
sm: sm,
}
n.tunNet = nw
if err := n.initTun(); err != nil {
return nil, err
}
var err error
n.conn, err = net.ListenUDP("udp4", &net.UDPAddr{IP: extIface.IfaceAddr, Port: port})
if err != nil {
return nil, fmt.Errorf("failed to start listening on UDP socket: %v", err)
}
n.ctl, n.ctl2, err = newCtlSockets()
if err != nil {
return nil, fmt.Errorf("failed to create control socket: %v", err)
}
return n, nil
}
func (n *network) Run(ctx context.Context) {
defer func() {
n.tun.Close()
n.conn.Close()
n.ctl.Close()
n.ctl2.Close()
}()
// one for each goroutine below
wg := sync.WaitGroup{}
defer wg.Wait()
wg.Add(1)
go func() {
runCProxy(n.tun, n.conn, n.ctl2, n.tunNet.IP, n.MTU())
wg.Done()
}()
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()
}()
for {
select {
case evtBatch := <-evts:
n.processSubnetEvents(evtBatch)
case <-ctx.Done():
stopProxy(n.ctl)
return
}
}
}
func (n *network) MTU() int {
return n.ExtIface.Iface.MTU - encapOverhead
}
func newCtlSockets() (*os.File, *os.File, error) {
fds, err := syscall.Socketpair(syscall.AF_UNIX, syscall.SOCK_SEQPACKET, 0)
if err != nil {
return nil, nil, err
}
f1 := os.NewFile(uintptr(fds[0]), "ctl")
f2 := os.NewFile(uintptr(fds[1]), "ctl")
return f1, f2, nil
}
func (n *network) initTun() error {
var tunName string
var err error
n.tun, tunName, err = ip.OpenTun("flannel%d")
if err != nil {
return fmt.Errorf("failed to open TUN device: %v", err)
}
err = configureIface(tunName, n.tunNet, n.MTU())
return err
}
func configureIface(ifname string, ipn ip.IP4Net, mtu int) error {
iface, err := netlink.LinkByName(ifname)
if err != nil {
return fmt.Errorf("failed to lookup interface %v", ifname)
}
// Ensure that the device has a /32 address so that no broadcast routes are created.
// This IP is just used as a source address for host to workload traffic (so
// the return path for the traffic has an address on the flannel network to use as the destination)
ipnLocal := ipn
ipnLocal.PrefixLen = 32
err = netlink.AddrAdd(iface, &netlink.Addr{IPNet: ipnLocal.ToIPNet(), Label: ""})
if err != nil {
return fmt.Errorf("failed to add IP address %v to %v: %v", ipnLocal.String(), ifname, err)
}
err = netlink.LinkSetMTU(iface, mtu)
if err != nil {
return fmt.Errorf("failed to set MTU for %v: %v", ifname, err)
}
err = netlink.LinkSetUp(iface)
if err != nil {
return fmt.Errorf("failed to set interface %v to UP state: %v", ifname, err)
}
// explicitly add a route since there might be a route for a subnet already
// installed by Docker and then it won't get auto added
err = netlink.RouteAdd(&netlink.Route{
LinkIndex: iface.Attrs().Index,
Scope: netlink.SCOPE_UNIVERSE,
Dst: ipn.Network().ToIPNet(),
})
if err != nil && err != syscall.EEXIST {
return fmt.Errorf("failed to add route (%v -> %v): %v", ipn.Network().String(), ifname, err)
}
return nil
}
func (n *network) processSubnetEvents(batch []subnet.Event) {
for _, evt := range batch {
switch evt.Type {
case subnet.EventAdded:
log.Info("Subnet added: ", evt.Lease.Subnet)
setRoute(n.ctl, evt.Lease.Subnet, evt.Lease.Attrs.PublicIP, n.port)
case subnet.EventRemoved:
log.Info("Subnet removed: ", evt.Lease.Subnet)
removeRoute(n.ctl, evt.Lease.Subnet)
default:
log.Error("Internal error: unknown event type: ", int(evt.Type))
}
}
}