Golang ns.WithNetNSPath函數代碼示例

func setupVeth(netns string, br *netlink.Bridge, ifName string, mtu int) error {
	var hostVethName string

	err := ns.WithNetNSPath(netns, false, func(hostNS *os.File) 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)
	}

	return nil
}

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 {
		h := sha512.Sum512([]byte(args.ContainerID))
		chain := fmt.Sprintf("CNI-%s-%x", conf.Name, h[:8])
		if err = ip.TeardownIPMasq(ipn, chain); err != nil {
			return err
		}
	}

	return ipam.ExecDel(conf.IPAM.Type, args.StdinData)
}

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 cmdAdd(args *skel.CmdArgs) error {
	n, err := loadNetConf(args.StdinData)
	if err != nil {
		return err
	}

	br, err := setupBridge(n)
	if err != nil {
		return err
	}

	if err = setupVeth(args.Netns, br, args.IfName, n.MTU); 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
	}

	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)
	}

	err = ns.WithNetNSPath(args.Netns, false, func(hostNS *os.File) error {
		return ipam.ConfigureIface(args.IfName, result)
	})
	if 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 := "CNI-" + n.Name
		if err = ip.SetupIPMasq(ip.Network(&result.IP4.IP), chain); err != nil {
			return err
		}
	}

	return result.Print()
}

func cmdAdd(args *skel.CmdArgs) error {
	tuningConf := TuningConf{}
	if err := json.Unmarshal(args.StdinData, &tuningConf); err != nil {
		return fmt.Errorf("failed to load netconf: %v", err)
	}

	// The directory /proc/sys/net is per network namespace. Enter in the
	// network namespace before writing on it.

	err := ns.WithNetNSPath(args.Netns, false, func(hostNS *os.File) error {
		for key, value := range tuningConf.SysCtl {
			fileName := filepath.Join("/proc/sys", strings.Replace(key, ".", "/", -1))
			fileName = filepath.Clean(fileName)

			// Refuse to modify sysctl parameters that don't belong
			// to the network subsystem.
			if !strings.HasPrefix(fileName, "/proc/sys/net/") {
				return fmt.Errorf("invalid net sysctl key: %q", key)
			}
			content := []byte(value)
			err := ioutil.WriteFile(fileName, content, 0644)
			if err != nil {
				return err
			}
		}
		return nil
	})
	if err != nil {
		return err
	}

	result := types.Result{}
	return result.Print()
}

func cmdDel(args *skel.CmdArgs) error {
	n, err := loadConf(args.StdinData)
	if err != nil {
		return err
	}

	err = plugin.ExecDel(n.IPAM.Type, args.StdinData)
	if err != nil {
		return err
	}

	return ns.WithNetNSPath(args.Netns, false, func(hostNS *os.File) error {
		return ip.DelLinkByName(args.IfName)
	})
}

func setupContainerVeth(netns, ifName string, mtu int, pr *plugin.Result) (string, error) {
	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
		}

		err = plugin.ConfigureIface(ifName, pr)
		if err != nil {
			return err
		}

		hostVethName = hostVeth.Attrs().Name

		return nil
	})
	return hostVethName, err
}

func cmdDel(args *skel.CmdArgs) error {
	args.IfName = "lo" // ignore config, this only works for loopback
	err := ns.WithNetNSPath(args.Netns, false, func(hostNS *os.File) error {
		link, err := netlink.LinkByName(args.IfName)
		if err != nil {
			return err // not tested
		}

		err = netlink.LinkSetDown(link)
		if err != nil {
			return err // not tested
		}

		return nil
	})
	if err != nil {
		return err // not tested
	}

	return nil
}

// AcquireLease gets an DHCP lease and then maintains it in the background
// by periodically renewing it. The acquired lease can be released by
// calling DHCPLease.Stop()
func AcquireLease(clientID, netns, ifName string) (*DHCPLease, error) {
	errCh := make(chan error, 1)
	l := &DHCPLease{
		clientID: clientID,
		stop:     make(chan struct{}),
	}

	log.Printf("%v: acquiring lease", clientID)

	l.wg.Add(1)
	go func() {
		errCh <- ns.WithNetNSPath(netns, true, func(_ *os.File) error {
			defer l.wg.Done()

			link, err := netlink.LinkByName(ifName)
			if err != nil {
				return fmt.Errorf("error looking up %q: %v", ifName, err)
			}

			l.link = link

			if err = l.acquire(); err != nil {
				return err
			}

			log.Printf("%v: lease acquired, expiration is %v", l.clientID, l.expireTime)

			errCh <- nil

			l.maintain()
			return nil
		})
	}()

	if err := <-errCh; err != nil {
		return nil, err
	}

	return l, nil
}

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
}

	})

	Context("when given a network namespace", func() {
		It("sets the lo device to UP", func() {
			command.Env = append(environ, fmt.Sprintf("CNI_COMMAND=%s", "ADD"))

			session, err := gexec.Start(command, GinkgoWriter, GinkgoWriter)
			Expect(err).NotTo(HaveOccurred())

			Eventually(session).Should(gbytes.Say(`{.*}`))
			Eventually(session).Should(gexec.Exit(0))

			var lo *net.Interface
			err = ns.WithNetNSPath(networkNS, true, func(hostNS *os.File) error {
				var err error
				lo, err = net.InterfaceByName("lo")
				return err
			})
			Expect(err).NotTo(HaveOccurred())

			Expect(lo.Flags & net.FlagUp).To(Equal(net.FlagUp))
		})

		It("sets the lo device to DOWN", func() {
			command.Env = append(environ, fmt.Sprintf("CNI_COMMAND=%s", "DEL"))

			session, err := gexec.Start(command, GinkgoWriter, GinkgoWriter)
			Expect(err).NotTo(HaveOccurred())

			Eventually(session).Should(gbytes.Say(``))
			Eventually(session).Should(gexec.Exit(0))

func (n *namespace) Execute(callback func(*os.File) error) error {
	return ns.WithNetNSPath(n.path, false, func(f *os.File) error {
		return callback(f)
	})
}