github.com/jjyr/docker@v1.5.0-rc2/daemon/networkdriver/bridge/driver.go (about)

     1  package bridge
     2  
     3  import (
     4  	"encoding/hex"
     5  	"errors"
     6  	"fmt"
     7  	"io/ioutil"
     8  	"net"
     9  	"os"
    10  	"strings"
    11  	"sync"
    12  
    13  	log "github.com/Sirupsen/logrus"
    14  	"github.com/docker/docker/daemon/networkdriver"
    15  	"github.com/docker/docker/daemon/networkdriver/ipallocator"
    16  	"github.com/docker/docker/daemon/networkdriver/portmapper"
    17  	"github.com/docker/docker/engine"
    18  	"github.com/docker/docker/nat"
    19  	"github.com/docker/docker/pkg/iptables"
    20  	"github.com/docker/docker/pkg/networkfs/resolvconf"
    21  	"github.com/docker/docker/pkg/parsers/kernel"
    22  	"github.com/docker/libcontainer/netlink"
    23  )
    24  
    25  const (
    26  	DefaultNetworkBridge     = "docker0"
    27  	MaxAllocatedPortAttempts = 10
    28  )
    29  
    30  // Network interface represents the networking stack of a container
    31  type networkInterface struct {
    32  	IP           net.IP
    33  	IPv6         net.IP
    34  	PortMappings []net.Addr // there are mappings to the host interfaces
    35  }
    36  
    37  type ifaces struct {
    38  	c map[string]*networkInterface
    39  	sync.Mutex
    40  }
    41  
    42  func (i *ifaces) Set(key string, n *networkInterface) {
    43  	i.Lock()
    44  	i.c[key] = n
    45  	i.Unlock()
    46  }
    47  
    48  func (i *ifaces) Get(key string) *networkInterface {
    49  	i.Lock()
    50  	res := i.c[key]
    51  	i.Unlock()
    52  	return res
    53  }
    54  
    55  var (
    56  	addrs = []string{
    57  		// Here we don't follow the convention of using the 1st IP of the range for the gateway.
    58  		// This is to use the same gateway IPs as the /24 ranges, which predate the /16 ranges.
    59  		// In theory this shouldn't matter - in practice there's bound to be a few scripts relying
    60  		// on the internal addressing or other stupid things like that.
    61  		// They shouldn't, but hey, let's not break them unless we really have to.
    62  		"172.17.42.1/16", // Don't use 172.16.0.0/16, it conflicts with EC2 DNS 172.16.0.23
    63  		"10.0.42.1/16",   // Don't even try using the entire /8, that's too intrusive
    64  		"10.1.42.1/16",
    65  		"10.42.42.1/16",
    66  		"172.16.42.1/24",
    67  		"172.16.43.1/24",
    68  		"172.16.44.1/24",
    69  		"10.0.42.1/24",
    70  		"10.0.43.1/24",
    71  		"192.168.42.1/24",
    72  		"192.168.43.1/24",
    73  		"192.168.44.1/24",
    74  	}
    75  
    76  	bridgeIface       string
    77  	bridgeIPv4Network *net.IPNet
    78  	bridgeIPv6Addr    net.IP
    79  	globalIPv6Network *net.IPNet
    80  
    81  	defaultBindingIP  = net.ParseIP("0.0.0.0")
    82  	currentInterfaces = ifaces{c: make(map[string]*networkInterface)}
    83  )
    84  
    85  func InitDriver(job *engine.Job) engine.Status {
    86  	var (
    87  		networkv4      *net.IPNet
    88  		networkv6      *net.IPNet
    89  		addrv4         net.Addr
    90  		addrsv6        []net.Addr
    91  		enableIPTables = job.GetenvBool("EnableIptables")
    92  		enableIPv6     = job.GetenvBool("EnableIPv6")
    93  		icc            = job.GetenvBool("InterContainerCommunication")
    94  		ipMasq         = job.GetenvBool("EnableIpMasq")
    95  		ipForward      = job.GetenvBool("EnableIpForward")
    96  		bridgeIP       = job.Getenv("BridgeIP")
    97  		bridgeIPv6     = "fe80::1/64"
    98  		fixedCIDR      = job.Getenv("FixedCIDR")
    99  		fixedCIDRv6    = job.Getenv("FixedCIDRv6")
   100  	)
   101  
   102  	if defaultIP := job.Getenv("DefaultBindingIP"); defaultIP != "" {
   103  		defaultBindingIP = net.ParseIP(defaultIP)
   104  	}
   105  
   106  	bridgeIface = job.Getenv("BridgeIface")
   107  	usingDefaultBridge := false
   108  	if bridgeIface == "" {
   109  		usingDefaultBridge = true
   110  		bridgeIface = DefaultNetworkBridge
   111  	}
   112  
   113  	addrv4, addrsv6, err := networkdriver.GetIfaceAddr(bridgeIface)
   114  
   115  	if err != nil {
   116  		// No Bridge existent. Create one
   117  		// If we're not using the default bridge, fail without trying to create it
   118  		if !usingDefaultBridge {
   119  			return job.Error(err)
   120  		}
   121  
   122  		// If the iface is not found, try to create it
   123  		if err := configureBridge(bridgeIP, bridgeIPv6, enableIPv6); err != nil {
   124  			return job.Error(err)
   125  		}
   126  
   127  		addrv4, addrsv6, err = networkdriver.GetIfaceAddr(bridgeIface)
   128  		if err != nil {
   129  			return job.Error(err)
   130  		}
   131  
   132  		if fixedCIDRv6 != "" {
   133  			// Setting route to global IPv6 subnet
   134  			log.Infof("Adding route to IPv6 network %q via device %q", fixedCIDRv6, bridgeIface)
   135  			if err := netlink.AddRoute(fixedCIDRv6, "", "", bridgeIface); err != nil {
   136  				log.Fatalf("Could not add route to IPv6 network %q via device %q", fixedCIDRv6, bridgeIface)
   137  			}
   138  		}
   139  	} else {
   140  		// Bridge exists already. Getting info...
   141  		// validate that the bridge ip matches the ip specified by BridgeIP
   142  		if bridgeIP != "" {
   143  			networkv4 = addrv4.(*net.IPNet)
   144  			bip, _, err := net.ParseCIDR(bridgeIP)
   145  			if err != nil {
   146  				return job.Error(err)
   147  			}
   148  			if !networkv4.IP.Equal(bip) {
   149  				return job.Errorf("bridge ip (%s) does not match existing bridge configuration %s", networkv4.IP, bip)
   150  			}
   151  		}
   152  
   153  		// a bridge might exist but not have any IPv6 addr associated with it yet
   154  		// (for example, an existing Docker installation that has only been used
   155  		// with IPv4 and docker0 already is set up) In that case, we can perform
   156  		// the bridge init for IPv6 here, else we will error out below if --ipv6=true
   157  		if len(addrsv6) == 0 && enableIPv6 {
   158  			if err := setupIPv6Bridge(bridgeIPv6); err != nil {
   159  				return job.Error(err)
   160  			}
   161  			// recheck addresses now that IPv6 is setup on the bridge
   162  			addrv4, addrsv6, err = networkdriver.GetIfaceAddr(bridgeIface)
   163  			if err != nil {
   164  				return job.Error(err)
   165  			}
   166  		}
   167  
   168  		// TODO: Check if route to fixedCIDRv6 is set
   169  	}
   170  
   171  	if enableIPv6 {
   172  		bip6, _, err := net.ParseCIDR(bridgeIPv6)
   173  		if err != nil {
   174  			return job.Error(err)
   175  		}
   176  		found := false
   177  		for _, addrv6 := range addrsv6 {
   178  			networkv6 = addrv6.(*net.IPNet)
   179  			if networkv6.IP.Equal(bip6) {
   180  				found = true
   181  				break
   182  			}
   183  		}
   184  		if !found {
   185  			return job.Errorf("bridge IPv6 does not match existing bridge configuration %s", bip6)
   186  		}
   187  	}
   188  
   189  	networkv4 = addrv4.(*net.IPNet)
   190  
   191  	log.Infof("enableIPv6 = %t", enableIPv6)
   192  	if enableIPv6 {
   193  		if len(addrsv6) == 0 {
   194  			return job.Error(errors.New("IPv6 enabled but no IPv6 detected"))
   195  		}
   196  		bridgeIPv6Addr = networkv6.IP
   197  	}
   198  
   199  	// Configure iptables for link support
   200  	if enableIPTables {
   201  		if err := setupIPTables(addrv4, icc, ipMasq); err != nil {
   202  			return job.Error(err)
   203  		}
   204  
   205  	}
   206  
   207  	if ipForward {
   208  		// Enable IPv4 forwarding
   209  		if err := ioutil.WriteFile("/proc/sys/net/ipv4/ip_forward", []byte{'1', '\n'}, 0644); err != nil {
   210  			job.Logf("WARNING: unable to enable IPv4 forwarding: %s\n", err)
   211  		}
   212  
   213  		if fixedCIDRv6 != "" {
   214  			// Enable IPv6 forwarding
   215  			if err := ioutil.WriteFile("/proc/sys/net/ipv6/conf/default/forwarding", []byte{'1', '\n'}, 0644); err != nil {
   216  				job.Logf("WARNING: unable to enable IPv6 default forwarding: %s\n", err)
   217  			}
   218  			if err := ioutil.WriteFile("/proc/sys/net/ipv6/conf/all/forwarding", []byte{'1', '\n'}, 0644); err != nil {
   219  				job.Logf("WARNING: unable to enable IPv6 all forwarding: %s\n", err)
   220  			}
   221  		}
   222  	}
   223  
   224  	// We can always try removing the iptables
   225  	if err := iptables.RemoveExistingChain("DOCKER", iptables.Nat); err != nil {
   226  		return job.Error(err)
   227  	}
   228  
   229  	if enableIPTables {
   230  		_, err := iptables.NewChain("DOCKER", bridgeIface, iptables.Nat)
   231  		if err != nil {
   232  			return job.Error(err)
   233  		}
   234  		chain, err := iptables.NewChain("DOCKER", bridgeIface, iptables.Filter)
   235  		if err != nil {
   236  			return job.Error(err)
   237  		}
   238  		portmapper.SetIptablesChain(chain)
   239  	}
   240  
   241  	bridgeIPv4Network = networkv4
   242  	if fixedCIDR != "" {
   243  		_, subnet, err := net.ParseCIDR(fixedCIDR)
   244  		if err != nil {
   245  			return job.Error(err)
   246  		}
   247  		log.Debugf("Subnet: %v", subnet)
   248  		if err := ipallocator.RegisterSubnet(bridgeIPv4Network, subnet); err != nil {
   249  			return job.Error(err)
   250  		}
   251  	}
   252  
   253  	if fixedCIDRv6 != "" {
   254  		_, subnet, err := net.ParseCIDR(fixedCIDRv6)
   255  		if err != nil {
   256  			return job.Error(err)
   257  		}
   258  		log.Debugf("Subnet: %v", subnet)
   259  		if err := ipallocator.RegisterSubnet(subnet, subnet); err != nil {
   260  			return job.Error(err)
   261  		}
   262  		globalIPv6Network = subnet
   263  	}
   264  
   265  	// Block BridgeIP in IP allocator
   266  	ipallocator.RequestIP(bridgeIPv4Network, bridgeIPv4Network.IP)
   267  
   268  	// https://github.com/docker/docker/issues/2768
   269  	job.Eng.Hack_SetGlobalVar("httpapi.bridgeIP", bridgeIPv4Network.IP)
   270  
   271  	for name, f := range map[string]engine.Handler{
   272  		"allocate_interface": Allocate,
   273  		"release_interface":  Release,
   274  		"allocate_port":      AllocatePort,
   275  		"link":               LinkContainers,
   276  	} {
   277  		if err := job.Eng.Register(name, f); err != nil {
   278  			return job.Error(err)
   279  		}
   280  	}
   281  	return engine.StatusOK
   282  }
   283  
   284  func setupIPTables(addr net.Addr, icc, ipmasq bool) error {
   285  	// Enable NAT
   286  
   287  	if ipmasq {
   288  		natArgs := []string{"POSTROUTING", "-t", "nat", "-s", addr.String(), "!", "-o", bridgeIface, "-j", "MASQUERADE"}
   289  
   290  		if !iptables.Exists(natArgs...) {
   291  			if output, err := iptables.Raw(append([]string{"-I"}, natArgs...)...); err != nil {
   292  				return fmt.Errorf("Unable to enable network bridge NAT: %s", err)
   293  			} else if len(output) != 0 {
   294  				return &iptables.ChainError{Chain: "POSTROUTING", Output: output}
   295  			}
   296  		}
   297  	}
   298  
   299  	var (
   300  		args       = []string{"FORWARD", "-i", bridgeIface, "-o", bridgeIface, "-j"}
   301  		acceptArgs = append(args, "ACCEPT")
   302  		dropArgs   = append(args, "DROP")
   303  	)
   304  
   305  	if !icc {
   306  		iptables.Raw(append([]string{"-D"}, acceptArgs...)...)
   307  
   308  		if !iptables.Exists(dropArgs...) {
   309  			log.Debugf("Disable inter-container communication")
   310  			if output, err := iptables.Raw(append([]string{"-I"}, dropArgs...)...); err != nil {
   311  				return fmt.Errorf("Unable to prevent intercontainer communication: %s", err)
   312  			} else if len(output) != 0 {
   313  				return fmt.Errorf("Error disabling intercontainer communication: %s", output)
   314  			}
   315  		}
   316  	} else {
   317  		iptables.Raw(append([]string{"-D"}, dropArgs...)...)
   318  
   319  		if !iptables.Exists(acceptArgs...) {
   320  			log.Debugf("Enable inter-container communication")
   321  			if output, err := iptables.Raw(append([]string{"-I"}, acceptArgs...)...); err != nil {
   322  				return fmt.Errorf("Unable to allow intercontainer communication: %s", err)
   323  			} else if len(output) != 0 {
   324  				return fmt.Errorf("Error enabling intercontainer communication: %s", output)
   325  			}
   326  		}
   327  	}
   328  
   329  	// Accept all non-intercontainer outgoing packets
   330  	outgoingArgs := []string{"FORWARD", "-i", bridgeIface, "!", "-o", bridgeIface, "-j", "ACCEPT"}
   331  	if !iptables.Exists(outgoingArgs...) {
   332  		if output, err := iptables.Raw(append([]string{"-I"}, outgoingArgs...)...); err != nil {
   333  			return fmt.Errorf("Unable to allow outgoing packets: %s", err)
   334  		} else if len(output) != 0 {
   335  			return &iptables.ChainError{Chain: "FORWARD outgoing", Output: output}
   336  		}
   337  	}
   338  
   339  	// Accept incoming packets for existing connections
   340  	existingArgs := []string{"FORWARD", "-o", bridgeIface, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
   341  
   342  	if !iptables.Exists(existingArgs...) {
   343  		if output, err := iptables.Raw(append([]string{"-I"}, existingArgs...)...); err != nil {
   344  			return fmt.Errorf("Unable to allow incoming packets: %s", err)
   345  		} else if len(output) != 0 {
   346  			return &iptables.ChainError{Chain: "FORWARD incoming", Output: output}
   347  		}
   348  	}
   349  	return nil
   350  }
   351  
   352  // configureBridge attempts to create and configure a network bridge interface named `bridgeIface` on the host
   353  // If bridgeIP is empty, it will try to find a non-conflicting IP from the Docker-specified private ranges
   354  // If the bridge `bridgeIface` already exists, it will only perform the IP address association with the existing
   355  // bridge (fixes issue #8444)
   356  // If an address which doesn't conflict with existing interfaces can't be found, an error is returned.
   357  func configureBridge(bridgeIP string, bridgeIPv6 string, enableIPv6 bool) error {
   358  	nameservers := []string{}
   359  	resolvConf, _ := resolvconf.Get()
   360  	// we don't check for an error here, because we don't really care
   361  	// if we can't read /etc/resolv.conf. So instead we skip the append
   362  	// if resolvConf is nil. It either doesn't exist, or we can't read it
   363  	// for some reason.
   364  	if resolvConf != nil {
   365  		nameservers = append(nameservers, resolvconf.GetNameserversAsCIDR(resolvConf)...)
   366  	}
   367  
   368  	var ifaceAddr string
   369  	if len(bridgeIP) != 0 {
   370  		_, _, err := net.ParseCIDR(bridgeIP)
   371  		if err != nil {
   372  			return err
   373  		}
   374  		ifaceAddr = bridgeIP
   375  	} else {
   376  		for _, addr := range addrs {
   377  			_, dockerNetwork, err := net.ParseCIDR(addr)
   378  			if err != nil {
   379  				return err
   380  			}
   381  			if err := networkdriver.CheckNameserverOverlaps(nameservers, dockerNetwork); err == nil {
   382  				if err := networkdriver.CheckRouteOverlaps(dockerNetwork); err == nil {
   383  					ifaceAddr = addr
   384  					break
   385  				} else {
   386  					log.Debugf("%s %s", addr, err)
   387  				}
   388  			}
   389  		}
   390  	}
   391  
   392  	if ifaceAddr == "" {
   393  		return fmt.Errorf("Could not find a free IP address range for interface '%s'. Please configure its address manually and run 'docker -b %s'", bridgeIface, bridgeIface)
   394  	}
   395  	log.Debugf("Creating bridge %s with network %s", bridgeIface, ifaceAddr)
   396  
   397  	if err := createBridgeIface(bridgeIface); err != nil {
   398  		// the bridge may already exist, therefore we can ignore an "exists" error
   399  		if !os.IsExist(err) {
   400  			return err
   401  		}
   402  	}
   403  
   404  	iface, err := net.InterfaceByName(bridgeIface)
   405  	if err != nil {
   406  		return err
   407  	}
   408  
   409  	ipAddr, ipNet, err := net.ParseCIDR(ifaceAddr)
   410  	if err != nil {
   411  		return err
   412  	}
   413  
   414  	if err := netlink.NetworkLinkAddIp(iface, ipAddr, ipNet); err != nil {
   415  		return fmt.Errorf("Unable to add private network: %s", err)
   416  	}
   417  
   418  	if enableIPv6 {
   419  		if err := setupIPv6Bridge(bridgeIPv6); err != nil {
   420  			return err
   421  		}
   422  	}
   423  
   424  	if err := netlink.NetworkLinkUp(iface); err != nil {
   425  		return fmt.Errorf("Unable to start network bridge: %s", err)
   426  	}
   427  	return nil
   428  }
   429  
   430  func setupIPv6Bridge(bridgeIPv6 string) error {
   431  
   432  	iface, err := net.InterfaceByName(bridgeIface)
   433  	if err != nil {
   434  		return err
   435  	}
   436  	// Enable IPv6 on the bridge
   437  	procFile := "/proc/sys/net/ipv6/conf/" + iface.Name + "/disable_ipv6"
   438  	if err := ioutil.WriteFile(procFile, []byte{'0', '\n'}, 0644); err != nil {
   439  		return fmt.Errorf("Unable to enable IPv6 addresses on bridge: %v", err)
   440  	}
   441  
   442  	ipAddr6, ipNet6, err := net.ParseCIDR(bridgeIPv6)
   443  	if err != nil {
   444  		return fmt.Errorf("Unable to parse bridge IPv6 address: %q, error: %v", bridgeIPv6, err)
   445  	}
   446  
   447  	if err := netlink.NetworkLinkAddIp(iface, ipAddr6, ipNet6); err != nil {
   448  		return fmt.Errorf("Unable to add private IPv6 network: %v", err)
   449  	}
   450  
   451  	return nil
   452  }
   453  
   454  func createBridgeIface(name string) error {
   455  	kv, err := kernel.GetKernelVersion()
   456  	// only set the bridge's mac address if the kernel version is > 3.3
   457  	// before that it was not supported
   458  	setBridgeMacAddr := err == nil && (kv.Kernel >= 3 && kv.Major >= 3)
   459  	log.Debugf("setting bridge mac address = %v", setBridgeMacAddr)
   460  	return netlink.CreateBridge(name, setBridgeMacAddr)
   461  }
   462  
   463  // Generate a IEEE802 compliant MAC address from the given IP address.
   464  //
   465  // The generator is guaranteed to be consistent: the same IP will always yield the same
   466  // MAC address. This is to avoid ARP cache issues.
   467  func generateMacAddr(ip net.IP) net.HardwareAddr {
   468  	hw := make(net.HardwareAddr, 6)
   469  
   470  	// The first byte of the MAC address has to comply with these rules:
   471  	// 1. Unicast: Set the least-significant bit to 0.
   472  	// 2. Address is locally administered: Set the second-least-significant bit (U/L) to 1.
   473  	// 3. As "small" as possible: The veth address has to be "smaller" than the bridge address.
   474  	hw[0] = 0x02
   475  
   476  	// The first 24 bits of the MAC represent the Organizationally Unique Identifier (OUI).
   477  	// Since this address is locally administered, we can do whatever we want as long as
   478  	// it doesn't conflict with other addresses.
   479  	hw[1] = 0x42
   480  
   481  	// Insert the IP address into the last 32 bits of the MAC address.
   482  	// This is a simple way to guarantee the address will be consistent and unique.
   483  	copy(hw[2:], ip.To4())
   484  
   485  	return hw
   486  }
   487  
   488  func linkLocalIPv6FromMac(mac string) (string, error) {
   489  	hx := strings.Replace(mac, ":", "", -1)
   490  	hw, err := hex.DecodeString(hx)
   491  	if err != nil {
   492  		return "", errors.New("Could not parse MAC address " + mac)
   493  	}
   494  
   495  	hw[0] ^= 0x2
   496  
   497  	return fmt.Sprintf("fe80::%x%x:%xff:fe%x:%x%x/64", hw[0], hw[1], hw[2], hw[3], hw[4], hw[5]), nil
   498  }
   499  
   500  // Allocate a network interface
   501  func Allocate(job *engine.Job) engine.Status {
   502  	var (
   503  		ip            net.IP
   504  		mac           net.HardwareAddr
   505  		err           error
   506  		id            = job.Args[0]
   507  		requestedIP   = net.ParseIP(job.Getenv("RequestedIP"))
   508  		requestedIPv6 = net.ParseIP(job.Getenv("RequestedIPv6"))
   509  		globalIPv6    net.IP
   510  	)
   511  
   512  	if requestedIP != nil {
   513  		ip, err = ipallocator.RequestIP(bridgeIPv4Network, requestedIP)
   514  	} else {
   515  		ip, err = ipallocator.RequestIP(bridgeIPv4Network, nil)
   516  	}
   517  	if err != nil {
   518  		return job.Error(err)
   519  	}
   520  
   521  	// If no explicit mac address was given, generate a random one.
   522  	if mac, err = net.ParseMAC(job.Getenv("RequestedMac")); err != nil {
   523  		mac = generateMacAddr(ip)
   524  	}
   525  
   526  	if globalIPv6Network != nil {
   527  		// if globalIPv6Network Size is at least a /80 subnet generate IPv6 address from MAC address
   528  		netmask_ones, _ := globalIPv6Network.Mask.Size()
   529  		if requestedIPv6 == nil && netmask_ones <= 80 {
   530  			requestedIPv6 = globalIPv6Network.IP
   531  			for i, h := range mac {
   532  				requestedIPv6[i+10] = h
   533  			}
   534  		}
   535  
   536  		globalIPv6, err = ipallocator.RequestIP(globalIPv6Network, requestedIPv6)
   537  		if err != nil {
   538  			log.Errorf("Allocator: RequestIP v6: %s", err.Error())
   539  			return job.Error(err)
   540  		}
   541  		log.Infof("Allocated IPv6 %s", globalIPv6)
   542  	}
   543  
   544  	out := engine.Env{}
   545  	out.Set("IP", ip.String())
   546  	out.Set("Mask", bridgeIPv4Network.Mask.String())
   547  	out.Set("Gateway", bridgeIPv4Network.IP.String())
   548  	out.Set("MacAddress", mac.String())
   549  	out.Set("Bridge", bridgeIface)
   550  
   551  	size, _ := bridgeIPv4Network.Mask.Size()
   552  	out.SetInt("IPPrefixLen", size)
   553  
   554  	// if linklocal IPv6
   555  	localIPv6Net, err := linkLocalIPv6FromMac(mac.String())
   556  	if err != nil {
   557  		return job.Error(err)
   558  	}
   559  	localIPv6, _, _ := net.ParseCIDR(localIPv6Net)
   560  	out.Set("LinkLocalIPv6", localIPv6.String())
   561  	out.Set("MacAddress", mac.String())
   562  
   563  	if globalIPv6Network != nil {
   564  		out.Set("GlobalIPv6", globalIPv6.String())
   565  		sizev6, _ := globalIPv6Network.Mask.Size()
   566  		out.SetInt("GlobalIPv6PrefixLen", sizev6)
   567  		out.Set("IPv6Gateway", bridgeIPv6Addr.String())
   568  	}
   569  
   570  	currentInterfaces.Set(id, &networkInterface{
   571  		IP:   ip,
   572  		IPv6: globalIPv6,
   573  	})
   574  
   575  	out.WriteTo(job.Stdout)
   576  
   577  	return engine.StatusOK
   578  }
   579  
   580  // release an interface for a select ip
   581  func Release(job *engine.Job) engine.Status {
   582  	var (
   583  		id                 = job.Args[0]
   584  		containerInterface = currentInterfaces.Get(id)
   585  	)
   586  
   587  	if containerInterface == nil {
   588  		return job.Errorf("No network information to release for %s", id)
   589  	}
   590  
   591  	for _, nat := range containerInterface.PortMappings {
   592  		if err := portmapper.Unmap(nat); err != nil {
   593  			log.Infof("Unable to unmap port %s: %s", nat, err)
   594  		}
   595  	}
   596  
   597  	if err := ipallocator.ReleaseIP(bridgeIPv4Network, containerInterface.IP); err != nil {
   598  		log.Infof("Unable to release IPv4 %s", err)
   599  	}
   600  	if globalIPv6Network != nil {
   601  		if err := ipallocator.ReleaseIP(globalIPv6Network, containerInterface.IPv6); err != nil {
   602  			log.Infof("Unable to release IPv6 %s", err)
   603  		}
   604  	}
   605  	return engine.StatusOK
   606  }
   607  
   608  // Allocate an external port and map it to the interface
   609  func AllocatePort(job *engine.Job) engine.Status {
   610  	var (
   611  		err error
   612  
   613  		ip            = defaultBindingIP
   614  		id            = job.Args[0]
   615  		hostIP        = job.Getenv("HostIP")
   616  		hostPort      = job.GetenvInt("HostPort")
   617  		containerPort = job.GetenvInt("ContainerPort")
   618  		proto         = job.Getenv("Proto")
   619  		network       = currentInterfaces.Get(id)
   620  	)
   621  
   622  	if hostIP != "" {
   623  		ip = net.ParseIP(hostIP)
   624  		if ip == nil {
   625  			return job.Errorf("Bad parameter: invalid host ip %s", hostIP)
   626  		}
   627  	}
   628  
   629  	// host ip, proto, and host port
   630  	var container net.Addr
   631  	switch proto {
   632  	case "tcp":
   633  		container = &net.TCPAddr{IP: network.IP, Port: containerPort}
   634  	case "udp":
   635  		container = &net.UDPAddr{IP: network.IP, Port: containerPort}
   636  	default:
   637  		return job.Errorf("unsupported address type %s", proto)
   638  	}
   639  
   640  	//
   641  	// Try up to 10 times to get a port that's not already allocated.
   642  	//
   643  	// In the event of failure to bind, return the error that portmapper.Map
   644  	// yields.
   645  	//
   646  
   647  	var host net.Addr
   648  	for i := 0; i < MaxAllocatedPortAttempts; i++ {
   649  		if host, err = portmapper.Map(container, ip, hostPort); err == nil {
   650  			break
   651  		}
   652  		// There is no point in immediately retrying to map an explicitly
   653  		// chosen port.
   654  		if hostPort != 0 {
   655  			job.Logf("Failed to allocate and map port %d: %s", hostPort, err)
   656  			break
   657  		}
   658  		job.Logf("Failed to allocate and map port: %s, retry: %d", err, i+1)
   659  	}
   660  
   661  	if err != nil {
   662  		return job.Error(err)
   663  	}
   664  
   665  	network.PortMappings = append(network.PortMappings, host)
   666  
   667  	out := engine.Env{}
   668  	switch netAddr := host.(type) {
   669  	case *net.TCPAddr:
   670  		out.Set("HostIP", netAddr.IP.String())
   671  		out.SetInt("HostPort", netAddr.Port)
   672  	case *net.UDPAddr:
   673  		out.Set("HostIP", netAddr.IP.String())
   674  		out.SetInt("HostPort", netAddr.Port)
   675  	}
   676  	if _, err := out.WriteTo(job.Stdout); err != nil {
   677  		return job.Error(err)
   678  	}
   679  
   680  	return engine.StatusOK
   681  }
   682  
   683  func LinkContainers(job *engine.Job) engine.Status {
   684  	var (
   685  		action       = job.Args[0]
   686  		nfAction     iptables.Action
   687  		childIP      = job.Getenv("ChildIP")
   688  		parentIP     = job.Getenv("ParentIP")
   689  		ignoreErrors = job.GetenvBool("IgnoreErrors")
   690  		ports        = job.GetenvList("Ports")
   691  	)
   692  
   693  	switch action {
   694  	case "-A":
   695  		nfAction = iptables.Append
   696  	case "-I":
   697  		nfAction = iptables.Insert
   698  	case "-D":
   699  		nfAction = iptables.Delete
   700  	default:
   701  		return job.Errorf("Invalid action '%s' specified", action)
   702  	}
   703  
   704  	ip1 := net.ParseIP(parentIP)
   705  	if ip1 == nil {
   706  		return job.Errorf("parent IP '%s' is invalid", parentIP)
   707  	}
   708  	ip2 := net.ParseIP(childIP)
   709  	if ip2 == nil {
   710  		return job.Errorf("child IP '%s' is invalid", childIP)
   711  	}
   712  
   713  	chain := iptables.Chain{Name: "DOCKER", Bridge: bridgeIface}
   714  	for _, p := range ports {
   715  		port := nat.Port(p)
   716  		if err := chain.Link(nfAction, ip1, ip2, port.Int(), port.Proto()); !ignoreErrors && err != nil {
   717  			return job.Error(err)
   718  		}
   719  	}
   720  	return engine.StatusOK
   721  }