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ptp.go
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ptp.go
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// Copyright 2015 CNI 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 main
import (
"encoding/json"
"errors"
"fmt"
"net"
"os"
"runtime"
"github.com/vishvananda/netlink"
"github.com/appc/cni/pkg/ip"
"github.com/appc/cni/pkg/ipam"
"github.com/appc/cni/pkg/ns"
"github.com/appc/cni/pkg/skel"
"github.com/appc/cni/pkg/types"
"github.com/appc/cni/pkg/utils"
)
func init() {
// this ensures that main runs only on main thread (thread group leader).
// since namespace ops (unshare, setns) are done for a single thread, we
// must ensure that the goroutine does not jump from OS thread to thread
runtime.LockOSThread()
}
type NetConf struct {
types.NetConf
IPMasq bool `json:"ipMasq"`
MTU int `json:"mtu"`
}
func setupContainerVeth(netns, ifName string, mtu int, pr *types.Result) (string, error) {
// The IPAM result will be something like IP=192.168.3.5/24, GW=192.168.3.1.
// What we want is really a point-to-point link but veth does not support IFF_POINTOPONT.
// Next best thing would be to let it ARP but set interface to 192.168.3.5/32 and
// add a route like "192.168.3.0/24 via 192.168.3.1 dev $ifName".
// Unfortunately that won't work as the GW will be outside the interface's subnet.
// Our solution is to configure the interface with 192.168.3.5/24, then delete the
// "192.168.3.0/24 dev $ifName" route that was automatically added. Then we add
// "192.168.3.1/32 dev $ifName" and "192.168.3.0/24 via 192.168.3.1 dev $ifName".
// In other words we force all traffic to ARP via the gateway except for GW itself.
var hostVethName string
err := ns.WithNetNSPath(netns, false, func(hostNS *os.File) error {
hostVeth, _, err := ip.SetupVeth(ifName, mtu, hostNS)
if err != nil {
return err
}
if err = ipam.ConfigureIface(ifName, pr); err != nil {
return err
}
contVeth, err := netlink.LinkByName(ifName)
if err != nil {
return fmt.Errorf("failed to look up %q: %v", ifName, err)
}
// Delete the route that was automatically added
route := netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.IP.IP.Mask(pr.IP4.IP.Mask),
Mask: pr.IP4.IP.Mask,
},
Scope: netlink.SCOPE_NOWHERE,
}
if err := netlink.RouteDel(&route); err != nil {
return fmt.Errorf("failed to delete route %v: %v", route, err)
}
for _, r := range []netlink.Route{
netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.Gateway,
Mask: net.CIDRMask(32, 32),
},
Scope: netlink.SCOPE_LINK,
Src: pr.IP4.IP.IP,
},
netlink.Route{
LinkIndex: contVeth.Attrs().Index,
Dst: &net.IPNet{
IP: pr.IP4.IP.IP.Mask(pr.IP4.IP.Mask),
Mask: pr.IP4.IP.Mask,
},
Scope: netlink.SCOPE_UNIVERSE,
Gw: pr.IP4.Gateway,
Src: pr.IP4.IP.IP,
},
} {
if err := netlink.RouteAdd(&r); err != nil {
return fmt.Errorf("failed to add route %v: %v", r, err)
}
}
hostVethName = hostVeth.Attrs().Name
return nil
})
return hostVethName, err
}
func setupHostVeth(vethName string, ipConf *types.IPConfig) error {
// hostVeth moved namespaces and may have a new ifindex
veth, err := netlink.LinkByName(vethName)
if err != nil {
return fmt.Errorf("failed to lookup %q: %v", vethName, err)
}
// TODO(eyakubovich): IPv6
ipn := &net.IPNet{
IP: ipConf.Gateway,
Mask: net.CIDRMask(32, 32),
}
addr := &netlink.Addr{IPNet: ipn, Label: ""}
if err = netlink.AddrAdd(veth, addr); err != nil {
return fmt.Errorf("failed to add IP addr (%#v) to veth: %v", ipn, err)
}
ipn = &net.IPNet{
IP: ipConf.IP.IP,
Mask: net.CIDRMask(32, 32),
}
// dst happens to be the same as IP/net of host veth
if err = ip.AddHostRoute(ipn, nil, veth); err != nil && !os.IsExist(err) {
return fmt.Errorf("failed to add route on host: %v", err)
}
return nil
}
func cmdAdd(args *skel.CmdArgs) error {
conf := NetConf{}
if err := json.Unmarshal(args.StdinData, &conf); err != nil {
return fmt.Errorf("failed to load netconf: %v", err)
}
if err := ip.EnableIP4Forward(); err != nil {
return fmt.Errorf("failed to enable forwarding: %v", err)
}
// run the IPAM plugin and get back the config to apply
result, err := ipam.ExecAdd(conf.IPAM.Type, args.StdinData)
if err != nil {
return err
}
if result.IP4 == nil {
return errors.New("IPAM plugin returned missing IPv4 config")
}
hostVethName, err := setupContainerVeth(args.Netns, args.IfName, conf.MTU, result)
if err != nil {
return err
}
if err = setupHostVeth(hostVethName, result.IP4); err != nil {
return err
}
if conf.IPMasq {
chain := utils.FormatChainName(conf.Name, args.ContainerID)
comment := utils.FormatComment(conf.Name, args.ContainerID)
if err = ip.SetupIPMasq(&result.IP4.IP, chain, comment); err != nil {
return err
}
}
result.DNS = conf.DNS
return result.Print()
}
func cmdDel(args *skel.CmdArgs) error {
conf := NetConf{}
if err := json.Unmarshal(args.StdinData, &conf); err != nil {
return fmt.Errorf("failed to load netconf: %v", err)
}
var ipn *net.IPNet
err := ns.WithNetNSPath(args.Netns, false, func(hostNS *os.File) error {
var err error
ipn, err = ip.DelLinkByNameAddr(args.IfName, netlink.FAMILY_V4)
return err
})
if err != nil {
return err
}
if conf.IPMasq {
chain := utils.FormatChainName(conf.Name, args.ContainerID)
comment := utils.FormatComment(conf.Name, args.ContainerID)
if err = ip.TeardownIPMasq(ipn, chain, comment); err != nil {
return err
}
}
return ipam.ExecDel(conf.IPAM.Type, args.StdinData)
}
func main() {
skel.PluginMain(cmdAdd, cmdDel)
}