Add CNI networking to system-docker

vendor/github.com/containernetworking/cni/plugins/main/bridge/bridge.go

@@ -0,0 +1,319 @@
+// Copyright 2014 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 bridge
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net"
+	"runtime"
+	"syscall"
+
+	"github.com/containernetworking/cni/pkg/ip"
+	"github.com/containernetworking/cni/pkg/ipam"
+	"github.com/containernetworking/cni/pkg/ns"
+	"github.com/containernetworking/cni/pkg/skel"
+	"github.com/containernetworking/cni/pkg/types"
+	"github.com/containernetworking/cni/pkg/utils"
+	"github.com/vishvananda/netlink"
+)
+
+const defaultBrName = "cni0"
+
+type NetConf struct {
+	types.NetConf
+	BrName      string `json:"bridge"`
+	IsGW        bool   `json:"isGateway"`
+	IsDefaultGW bool   `json:"isDefaultGateway"`
+	IPMasq      bool   `json:"ipMasq"`
+	MTU         int    `json:"mtu"`
+	HairpinMode bool   `json:"hairpinMode"`
+}
+
+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()
+}
+
+func loadNetConf(bytes []byte) (*NetConf, error) {
+	n := &NetConf{
+		BrName: defaultBrName,
+	}
+	if err := json.Unmarshal(bytes, n); err != nil {
+		return nil, fmt.Errorf("failed to load netconf: %v", err)
+	}
+	return n, nil
+}
+
+func ensureBridgeAddr(br *netlink.Bridge, ipn *net.IPNet) error {
+	addrs, err := netlink.AddrList(br, syscall.AF_INET)
+	if err != nil && err != syscall.ENOENT {
+		return fmt.Errorf("could not get list of IP addresses: %v", err)
+	}
+
+	// if there're no addresses on the bridge, it's ok -- we'll add one
+	if len(addrs) > 0 {
+		ipnStr := ipn.String()
+		for _, a := range addrs {
+			// string comp is actually easiest for doing IPNet comps
+			if a.IPNet.String() == ipnStr {
+				return nil
+			}
+		}
+		return fmt.Errorf("%q already has an IP address different from %v", br.Name, ipn.String())
+	}
+
+	addr := &netlink.Addr{IPNet: ipn, Label: ""}
+	if err := netlink.AddrAdd(br, addr); err != nil {
+		return fmt.Errorf("could not add IP address to %q: %v", br.Name, err)
+	}
+	return nil
+}
+
+func bridgeByName(name string) (*netlink.Bridge, error) {
+	l, err := netlink.LinkByName(name)
+	if err != nil {
+		return nil, fmt.Errorf("could not lookup %q: %v", name, err)
+	}
+	br, ok := l.(*netlink.Bridge)
+	if !ok {
+		return nil, fmt.Errorf("%q already exists but is not a bridge", name)
+	}
+	return br, nil
+}
+
+func ensureBridge(brName string, mtu int) (*netlink.Bridge, error) {
+	br := &netlink.Bridge{
+		LinkAttrs: netlink.LinkAttrs{
+			Name: brName,
+			MTU:  mtu,
+			// Let kernel use default txqueuelen; leaving it unset
+			// means 0, and a zero-length TX queue messes up FIFO
+			// traffic shapers which use TX queue length as the
+			// default packet limit
+			TxQLen: -1,
+		},
+	}
+
+	if err := netlink.LinkAdd(br); err != nil {
+		if err != syscall.EEXIST {
+			return nil, fmt.Errorf("could not add %q: %v", brName, err)
+		}
+
+		// it's ok if the device already exists as long as config is similar
+		br, err = bridgeByName(brName)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if err := netlink.LinkSetUp(br); err != nil {
+		return nil, err
+	}
+
+	return br, nil
+}
+
+func setupVeth(netns ns.NetNS, br *netlink.Bridge, ifName string, mtu int, hairpinMode bool) error {
+	var hostVethName string
+
+	err := netns.Do(func(hostNS ns.NetNS) error {
+		// create the veth pair in the container and move host end into host netns
+		hostVeth, _, err := ip.SetupVeth(ifName, mtu, hostNS)
+		if err != nil {
+			return err
+		}
+
+		hostVethName = hostVeth.Attrs().Name
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+
+	// need to lookup hostVeth again as its index has changed during ns move
+	hostVeth, err := netlink.LinkByName(hostVethName)
+	if err != nil {
+		return fmt.Errorf("failed to lookup %q: %v", hostVethName, err)
+	}
+
+	// connect host veth end to the bridge
+	if err = netlink.LinkSetMaster(hostVeth, br); err != nil {
+		return fmt.Errorf("failed to connect %q to bridge %v: %v", hostVethName, br.Attrs().Name, err)
+	}
+
+	// set hairpin mode
+	if err = netlink.LinkSetHairpin(hostVeth, hairpinMode); err != nil {
+		return fmt.Errorf("failed to setup hairpin mode for %v: %v", hostVethName, err)
+	}
+
+	return nil
+}
+
+func calcGatewayIP(ipn *net.IPNet) net.IP {
+	nid := ipn.IP.Mask(ipn.Mask)
+	return ip.NextIP(nid)
+}
+
+func setupBridge(n *NetConf) (*netlink.Bridge, error) {
+	// create bridge if necessary
+	br, err := ensureBridge(n.BrName, n.MTU)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create bridge %q: %v", n.BrName, err)
+	}
+
+	return br, nil
+}
+
+func cmdAdd(args *skel.CmdArgs) error {
+	n, err := loadNetConf(args.StdinData)
+	if err != nil {
+		return err
+	}
+
+	if n.IsDefaultGW {
+		n.IsGW = true
+	}
+
+	br, err := setupBridge(n)
+	if err != nil {
+		return err
+	}
+
+	netns, err := ns.GetNS(args.Netns)
+	if err != nil {
+		return fmt.Errorf("failed to open netns %q: %v", args.Netns, err)
+	}
+	defer netns.Close()
+
+	if err = setupVeth(netns, br, args.IfName, n.MTU, n.HairpinMode); err != nil {
+		return err
+	}
+
+	// run the IPAM plugin and get back the config to apply
+	result, err := ipam.ExecAdd(n.IPAM.Type, args.StdinData)
+	if err != nil {
+		return err
+	}
+
+	// TODO: make this optional when IPv6 is supported
+	if result.IP4 == nil {
+		return errors.New("IPAM plugin returned missing IPv4 config")
+	}
+
+	if result.IP4.Gateway == nil && n.IsGW {
+		result.IP4.Gateway = calcGatewayIP(&result.IP4.IP)
+	}
+
+	if err := netns.Do(func(_ ns.NetNS) error {
+		// set the default gateway if requested
+		if n.IsDefaultGW {
+			_, defaultNet, err := net.ParseCIDR("0.0.0.0/0")
+			if err != nil {
+				return err
+			}
+
+			for _, route := range result.IP4.Routes {
+				if defaultNet.String() == route.Dst.String() {
+					if route.GW != nil && !route.GW.Equal(result.IP4.Gateway) {
+						return fmt.Errorf(
+							"isDefaultGateway ineffective because IPAM sets default route via %q",
+							route.GW,
+						)
+					}
+				}
+			}
+
+			result.IP4.Routes = append(
+				result.IP4.Routes,
+				types.Route{Dst: *defaultNet, GW: result.IP4.Gateway},
+			)
+
+			// TODO: IPV6
+		}
+
+		return ipam.ConfigureIface(args.IfName, result)
+	}); err != nil {
+		return err
+	}
+
+	if n.IsGW {
+		gwn := &net.IPNet{
+			IP:   result.IP4.Gateway,
+			Mask: result.IP4.IP.Mask,
+		}
+
+		if err = ensureBridgeAddr(br, gwn); err != nil {
+			return err
+		}
+
+		if err := ip.EnableIP4Forward(); err != nil {
+			return fmt.Errorf("failed to enable forwarding: %v", err)
+		}
+	}
+
+	if n.IPMasq {
+		chain := utils.FormatChainName(n.Name, args.ContainerID)
+		comment := utils.FormatComment(n.Name, args.ContainerID)
+		if err = ip.SetupIPMasq(ip.Network(&result.IP4.IP), chain, comment); err != nil {
+			return err
+		}
+	}
+
+	result.DNS = n.DNS
+	return result.Print()
+}
+
+func cmdDel(args *skel.CmdArgs) error {
+	n, err := loadNetConf(args.StdinData)
+	if err != nil {
+		return err
+	}
+
+	if err := ipam.ExecDel(n.IPAM.Type, args.StdinData); err != nil {
+		return err
+	}
+
+	if args.Netns == "" {
+		return nil
+	}
+
+	var ipn *net.IPNet
+	err = ns.WithNetNSPath(args.Netns, func(_ ns.NetNS) error {
+		var err error
+		ipn, err = ip.DelLinkByNameAddr(args.IfName, netlink.FAMILY_V4)
+		return err
+	})
+	if err != nil {
+		return err
+	}
+
+	if n.IPMasq {
+		chain := utils.FormatChainName(n.Name, args.ContainerID)
+		comment := utils.FormatComment(n.Name, args.ContainerID)
+		if err = ip.TeardownIPMasq(ipn, chain, comment); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func Main() {
+	skel.PluginMain(cmdAdd, cmdDel)
+}