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cni.go
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cni.go
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package plugin
import (
"crypto/rand"
"encoding/json"
"fmt"
"net"
"github.com/appc/cni/pkg/ipam"
"github.com/appc/cni/pkg/skel"
"github.com/appc/cni/pkg/types"
"github.com/vishvananda/netlink"
"github.com/vishvananda/netns"
weaveapi "github.com/weaveworks/weave/api"
"github.com/weaveworks/weave/common"
weavenet "github.com/weaveworks/weave/net"
ipamplugin "github.com/weaveworks/weave/plugin/ipam"
)
var (
zeroNetwork = net.IPNet{IP: net.IPv4zero, Mask: net.IPv4Mask(0, 0, 0, 0)}
mask32 = net.IPv4Mask(0xff, 0xff, 0xff, 0xff)
)
type CNIPlugin struct {
weave *weaveapi.Client
}
func NewCNIPlugin(weave *weaveapi.Client) *CNIPlugin {
return &CNIPlugin{weave: weave}
}
func loadNetConf(bytes []byte) (*NetConf, error) {
n := &NetConf{
BrName: weavenet.WeaveBridgeName,
}
if err := json.Unmarshal(bytes, n); err != nil {
return nil, fmt.Errorf("failed to load netconf: %v", err)
}
return n, nil
}
func (c *CNIPlugin) CmdAdd(args *skel.CmdArgs) error {
conf, err := loadNetConf(args.StdinData)
if err != nil {
return err
}
if conf.IsGW {
return fmt.Errorf("Gateway functionality not supported")
}
if conf.IPMasq {
return fmt.Errorf("IP Masquerading functionality not supported")
}
var result *types.Result
// Default IPAM is Weave's own
if conf.IPAM.Type == "" {
result, err = ipamplugin.NewIpam(c.weave).Allocate(args)
} else {
result, err = ipam.ExecAdd(conf.IPAM.Type, args.StdinData)
}
if err != nil {
return fmt.Errorf("unable to allocate IP address: %s", err)
}
if result.IP4 == nil {
return fmt.Errorf("IPAM plugin failed to allocate IP address")
}
// If config says nothing about routes or gateway, default one will be via the bridge
if result.IP4.Routes == nil && result.IP4.Gateway == nil {
bridgeIP, err := findBridgeIP(conf.BrName, result.IP4.IP)
if err != nil {
return err
}
result.IP4.Gateway = bridgeIP
}
ns, err := netns.GetFromPath(args.Netns)
if err != nil {
return err
}
defer ns.Close()
id := args.ContainerID
if len(id) < 5 {
data := make([]byte, 5)
_, err := rand.Reader.Read(data)
if err != nil {
return err
}
id = fmt.Sprintf("%x", data)
}
if err := weavenet.AttachContainer(ns, id, args.IfName, conf.BrName, conf.MTU, false, []*net.IPNet{&result.IP4.IP}, false); err != nil {
return err
}
if err := weavenet.WithNetNSLink(ns, args.IfName, func(link netlink.Link) error {
return setupRoutes(link, args.IfName, result.IP4.IP, result.IP4.Gateway, result.IP4.Routes)
}); err != nil {
return fmt.Errorf("error setting up routes: %s", err)
}
result.DNS = conf.DNS
return result.Print()
}
func setupRoutes(link netlink.Link, name string, ipnet net.IPNet, gw net.IP, routes []types.Route) error {
var err error
if routes == nil { // If config says nothing about routes, add a default one
if !ipnet.Contains(gw) {
// The bridge IP is not on the same subnet; add a specific route to it
gw32 := &net.IPNet{IP: gw, Mask: mask32}
if err = weavenet.AddRoute(link, netlink.SCOPE_LINK, gw32, nil); err != nil {
return err
}
}
routes = []types.Route{{Dst: zeroNetwork}}
}
for _, r := range routes {
if r.GW != nil {
err = weavenet.AddRoute(link, netlink.SCOPE_UNIVERSE, &r.Dst, r.GW)
} else {
err = weavenet.AddRoute(link, netlink.SCOPE_UNIVERSE, &r.Dst, gw)
}
if err != nil {
return fmt.Errorf("failed to add route '%v via %v dev %v': %v", r.Dst, gw, name, err)
}
}
return nil
}
func findBridgeIP(bridgeName string, subnet net.IPNet) (net.IP, error) {
netdevs, err := common.GetBridgeNetDev(bridgeName)
if err != nil {
return nil, fmt.Errorf("Failed to get netdev for %q bridge: %s", bridgeName, err)
}
if len(netdevs) == 0 {
return nil, fmt.Errorf("Could not find %q bridge", bridgeName)
}
if len(netdevs[0].CIDRs) == 0 {
return nil, fmt.Errorf("Bridge %q has no IP addresses", bridgeName)
}
for _, cidr := range netdevs[0].CIDRs {
if subnet.Contains(cidr.IP) {
return cidr.IP, nil
}
}
// None in the required subnet; just return the first one
return netdevs[0].CIDRs[0].IP, nil
}
func (c *CNIPlugin) CmdDel(args *skel.CmdArgs) error {
conf, err := loadNetConf(args.StdinData)
if err != nil {
return err
}
ns, err := netns.GetFromPath(args.Netns)
if err != nil {
return err
}
defer ns.Close()
err = weavenet.WithNetNS(ns, func() error {
link, err := netlink.LinkByName(args.IfName)
if err != nil {
return err
}
return netlink.LinkDel(link)
})
if err != nil {
return fmt.Errorf("error removing interface: %s", err)
}
// Default IPAM is Weave's own
if conf.IPAM.Type == "" {
err = ipamplugin.NewIpam(c.weave).Release(args)
} else {
err = ipam.ExecDel(conf.IPAM.Type, args.StdinData)
}
if err != nil {
return fmt.Errorf("unable to release IP address: %s", err)
}
return nil
}
type NetConf struct {
types.NetConf
BrName string `json:"bridge"`
IsGW bool `json:"isGateway"`
IPMasq bool `json:"ipMasq"`
MTU int `json:"mtu"`
}