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device.go
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device.go
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// 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 vxlan
import (
"fmt"
"net"
"os"
"syscall"
"time"
log "github.com/golang/glog"
"github.com/vishvananda/netlink"
"github.com/vishvananda/netlink/nl"
"github.com/coreos/flannel/pkg/ip"
)
type vxlanDeviceAttrs struct {
vni uint32
name string
vtepIndex int
vtepAddr net.IP
vtepPort int
gbp bool
}
type vxlanDevice struct {
link *netlink.Vxlan
}
func sysctlSet(path, value string) error {
f, err := os.Create(path)
if err != nil {
return err
}
defer f.Close()
_, err = f.Write([]byte(value))
return err
}
func newVXLANDevice(devAttrs *vxlanDeviceAttrs) (*vxlanDevice, error) {
link := &netlink.Vxlan{
LinkAttrs: netlink.LinkAttrs{
Name: devAttrs.name,
},
VxlanId: int(devAttrs.vni),
VtepDevIndex: devAttrs.vtepIndex,
SrcAddr: devAttrs.vtepAddr,
Port: devAttrs.vtepPort,
Learning: false,
GBP: devAttrs.gbp,
}
link, err := ensureLink(link)
if err != nil {
return nil, err
}
// this enables ARP requests being sent to userspace via netlink
sysctlPath := fmt.Sprintf("/proc/sys/net/ipv4/neigh/%s/app_solicit", devAttrs.name)
if err := sysctlSet(sysctlPath, "3"); err != nil {
return nil, err
}
return &vxlanDevice{
link: link,
}, nil
}
func ensureLink(vxlan *netlink.Vxlan) (*netlink.Vxlan, error) {
err := netlink.LinkAdd(vxlan)
if err == syscall.EEXIST {
// it's ok if the device already exists as long as config is similar
existing, err := netlink.LinkByName(vxlan.Name)
if err != nil {
return nil, err
}
incompat := vxlanLinksIncompat(vxlan, existing)
if incompat == "" {
return existing.(*netlink.Vxlan), nil
}
// delete existing
log.Warningf("%q already exists with incompatable configuration: %v; recreating device", vxlan.Name, incompat)
if err = netlink.LinkDel(existing); err != nil {
return nil, fmt.Errorf("failed to delete interface: %v", err)
}
// create new
if err = netlink.LinkAdd(vxlan); err != nil {
return nil, fmt.Errorf("failed to create vxlan interface: %v", err)
}
} else if err != nil {
return nil, err
}
ifindex := vxlan.Index
link, err := netlink.LinkByIndex(vxlan.Index)
if err != nil {
return nil, fmt.Errorf("can't locate created vxlan device with index %v", ifindex)
}
var ok bool
if vxlan, ok = link.(*netlink.Vxlan); !ok {
return nil, fmt.Errorf("created vxlan device with index %v is not vxlan", ifindex)
}
return vxlan, nil
}
func (dev *vxlanDevice) Configure(ipn ip.IP4Net) error {
setAddr4(dev.link, ipn.ToIPNet())
if err := netlink.LinkSetUp(dev.link); err != nil {
return fmt.Errorf("failed to set interface %s to UP state: %s", dev.link.Attrs().Name, 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
route := netlink.Route{
LinkIndex: dev.link.Attrs().Index,
Scope: netlink.SCOPE_UNIVERSE,
Dst: ipn.Network().ToIPNet(),
}
if err := netlink.RouteAdd(&route); err != nil && err != syscall.EEXIST {
return fmt.Errorf("failed to add route (%s -> %s): %v", ipn.Network().String(), dev.link.Attrs().Name, err)
}
return nil
}
func (dev *vxlanDevice) Destroy() {
netlink.LinkDel(dev.link)
}
func (dev *vxlanDevice) MACAddr() net.HardwareAddr {
return dev.link.HardwareAddr
}
func (dev *vxlanDevice) MTU() int {
return dev.link.MTU
}
type neighbor struct {
MAC net.HardwareAddr
IP ip.IP4
}
func (dev *vxlanDevice) GetL2List() ([]netlink.Neigh, error) {
log.V(4).Infof("calling GetL2List() dev.link.Index: %d ", dev.link.Index)
return netlink.NeighList(dev.link.Index, syscall.AF_BRIDGE)
}
func (dev *vxlanDevice) AddL2(n neighbor) error {
log.V(4).Infof("calling NeighAdd: %v, %v", n.IP, n.MAC)
return netlink.NeighAdd(&netlink.Neigh{
LinkIndex: dev.link.Index,
State: netlink.NUD_PERMANENT,
Family: syscall.AF_BRIDGE,
Flags: netlink.NTF_SELF,
IP: n.IP.ToIP(),
HardwareAddr: n.MAC,
})
}
func (dev *vxlanDevice) DelL2(n neighbor) error {
log.V(4).Infof("calling NeighDel: %v, %v", n.IP, n.MAC)
return netlink.NeighDel(&netlink.Neigh{
LinkIndex: dev.link.Index,
Family: syscall.AF_BRIDGE,
Flags: netlink.NTF_SELF,
IP: n.IP.ToIP(),
HardwareAddr: n.MAC,
})
}
func (dev *vxlanDevice) AddL3(n neighbor) error {
log.V(4).Infof("calling NeighSet: %v, %v", n.IP, n.MAC)
return netlink.NeighSet(&netlink.Neigh{
LinkIndex: dev.link.Index,
State: netlink.NUD_REACHABLE,
Type: syscall.RTN_UNICAST,
IP: n.IP.ToIP(),
HardwareAddr: n.MAC,
})
}
func (dev *vxlanDevice) DelL3(n neighbor) error {
log.V(4).Infof("calling NeighDel: %v, %v", n.IP, n.MAC)
return netlink.NeighDel(&netlink.Neigh{
LinkIndex: dev.link.Index,
State: netlink.NUD_REACHABLE,
Type: syscall.RTN_UNICAST,
IP: n.IP.ToIP(),
HardwareAddr: n.MAC,
})
}
func (dev *vxlanDevice) MonitorMisses(misses chan *netlink.Neigh) {
nlsock, err := nl.Subscribe(syscall.NETLINK_ROUTE, syscall.RTNLGRP_NEIGH)
if err != nil {
log.Error("Failed to subscribe to netlink RTNLGRP_NEIGH messages")
return
}
for {
msgs, err := nlsock.Receive()
if err != nil {
log.Errorf("Failed to receive from netlink: %v ", err)
time.Sleep(1 * time.Second)
continue
}
for _, msg := range msgs {
dev.processNeighMsg(msg, misses)
}
}
}
func isNeighResolving(state int) bool {
return (state & (netlink.NUD_INCOMPLETE | netlink.NUD_STALE | netlink.NUD_DELAY | netlink.NUD_PROBE)) != 0
}
func (dev *vxlanDevice) processNeighMsg(msg syscall.NetlinkMessage, misses chan *netlink.Neigh) {
neigh, err := netlink.NeighDeserialize(msg.Data)
if err != nil {
log.Error("Failed to deserialize netlink ndmsg: %v", err)
return
}
if neigh.LinkIndex != dev.link.Index {
return
}
if msg.Header.Type != syscall.RTM_GETNEIGH && msg.Header.Type != syscall.RTM_NEWNEIGH {
return
}
if !isNeighResolving(neigh.State) {
// misses come with NUD_STALE bit set
return
}
misses <- neigh
}
func vxlanLinksIncompat(l1, l2 netlink.Link) string {
if l1.Type() != l2.Type() {
return fmt.Sprintf("link type: %v vs %v", l1.Type(), l2.Type())
}
v1 := l1.(*netlink.Vxlan)
v2 := l2.(*netlink.Vxlan)
if v1.VxlanId != v2.VxlanId {
return fmt.Sprintf("vni: %v vs %v", v1.VxlanId, v2.VxlanId)
}
if v1.VtepDevIndex > 0 && v2.VtepDevIndex > 0 && v1.VtepDevIndex != v2.VtepDevIndex {
return fmt.Sprintf("vtep (external) interface: %v vs %v", v1.VtepDevIndex, v2.VtepDevIndex)
}
if len(v1.SrcAddr) > 0 && len(v2.SrcAddr) > 0 && !v1.SrcAddr.Equal(v2.SrcAddr) {
return fmt.Sprintf("vtep (external) IP: %v vs %v", v1.SrcAddr, v2.SrcAddr)
}
if len(v1.Group) > 0 && len(v2.Group) > 0 && !v1.Group.Equal(v2.Group) {
return fmt.Sprintf("group address: %v vs %v", v1.Group, v2.Group)
}
if v1.L2miss != v2.L2miss {
return fmt.Sprintf("l2miss: %v vs %v", v1.L2miss, v2.L2miss)
}
if v1.Port > 0 && v2.Port > 0 && v1.Port != v2.Port {
return fmt.Sprintf("port: %v vs %v", v1.Port, v2.Port)
}
if v1.GBP != v2.GBP {
return fmt.Sprintf("gbp: %v vs %v", v1.GBP, v2.GBP)
}
return ""
}
// sets IP4 addr on link
func setAddr4(link *netlink.Vxlan, ipn *net.IPNet) error {
// 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 a decent address to use as the destination)
ipn.Mask = net.CIDRMask(32, 32)
addr := netlink.Addr{IPNet: ipn, Label: ""}
if err := netlink.AddrAdd(link, &addr); err != nil {
return fmt.Errorf("failed to add IP address %s to %s: %s", ipn.String(), link.Attrs().Name, err)
}
return nil
}