package docker
import (
"encoding/binary"
"errors"
"fmt"
"github.com/dotcloud/docker/iptables"
"github.com/dotcloud/docker/pkg/netlink"
"github.com/dotcloud/docker/proxy"
"github.com/dotcloud/docker/utils"
"log"
"net"
"strconv"
"sync"
"syscall"
"unsafe"
)
const (
DefaultNetworkBridge = "docker0"
DisableNetworkBridge = "none"
DefaultNetworkMtu = 1500
portRangeStart = 49153
portRangeEnd = 65535
siocBRADDBR = 0x89a0
)
// Calculates the first and last IP addresses in an IPNet
func networkRange(network *net.IPNet) (net.IP, net.IP) {
netIP := network.IP.To4()
firstIP := netIP.Mask(network.Mask)
lastIP := net.IPv4(0, 0, 0, 0).To4()
for i := 0; i < len(lastIP); i++ {
lastIP[i] = netIP[i] | ^network.Mask[i]
}
return firstIP, lastIP
}
// Detects overlap between one IPNet and another
func networkOverlaps(netX *net.IPNet, netY *net.IPNet) bool {
firstIP, _ := networkRange(netX)
if netY.Contains(firstIP) {
return true
}
firstIP, _ = networkRange(netY)
if netX.Contains(firstIP) {
return true
}
return false
}
// Converts a 4 bytes IP into a 32 bit integer
func ipToInt(ip net.IP) int32 {
return int32(binary.BigEndian.Uint32(ip.To4()))
}
// Converts 32 bit integer into a 4 bytes IP address
func intToIP(n int32) net.IP {
b := make([]byte, 4)
binary.BigEndian.PutUint32(b, uint32(n))
return net.IP(b)
}
// Given a netmask, calculates the number of available hosts
func networkSize(mask net.IPMask) int32 {
m := net.IPv4Mask(0, 0, 0, 0)
for i := 0; i < net.IPv4len; i++ {
m[i] = ^mask[i]
}
return int32(binary.BigEndian.Uint32(m)) + 1
}
func checkRouteOverlaps(networks []*net.IPNet, dockerNetwork *net.IPNet) error {
for _, network := range networks {
if networkOverlaps(dockerNetwork, network) {
return fmt.Errorf("Network %s is already routed: '%s'", dockerNetwork, network)
}
}
return nil
}
func checkNameserverOverlaps(nameservers []string, dockerNetwork *net.IPNet) error {
if len(nameservers) > 0 {
for _, ns := range nameservers {
_, nsNetwork, err := net.ParseCIDR(ns)
if err != nil {
return err
}
if networkOverlaps(dockerNetwork, nsNetwork) {
return fmt.Errorf("%s overlaps nameserver %s", dockerNetwork, nsNetwork)
}
}
}
return nil
}
// CreateBridgeIface creates a network bridge interface on the host system with the name `ifaceName`,
// and attempts to configure it with an address which doesn't conflict with any other interface on the host.
// If it can't find an address which doesn't conflict, it will return an error.
func CreateBridgeIface(config *DaemonConfig) error {
addrs := []string{
// Here we don't follow the convention of using the 1st IP of the range for the gateway.
// This is to use the same gateway IPs as the /24 ranges, which predate the /16 ranges.
// In theory this shouldn't matter - in practice there's bound to be a few scripts relying
// on the internal addressing or other stupid things like that.
// The shouldn't, but hey, let's not break them unless we really have to.
"172.17.42.1/16", // Don't use 172.16.0.0/16, it conflicts with EC2 DNS 172.16.0.23
"10.0.42.1/16", // Don't even try using the entire /8, that's too intrusive
"10.1.42.1/16",
"10.42.42.1/16",
"172.16.42.1/24",
"172.16.43.1/24",
"172.16.44.1/24",
"10.0.42.1/24",
"10.0.43.1/24",
"192.168.42.1/24",
"192.168.43.1/24",
"192.168.44.1/24",
}
nameservers := []string{}
resolvConf, _ := utils.GetResolvConf()
// we don't check for an error here, because we don't really care
// if we can't read /etc/resolv.conf. So instead we skip the append
// if resolvConf is nil. It either doesn't exist, or we can't read it
// for some reason.
if resolvConf != nil {
nameservers = append(nameservers, utils.GetNameserversAsCIDR(resolvConf)...)
}
var ifaceAddr string
if len(config.BridgeIp) != 0 {
_, _, err := net.ParseCIDR(config.BridgeIp)
if err != nil {
return err
}
ifaceAddr = config.BridgeIp
} else {
for _, addr := range addrs {
_, dockerNetwork, err := net.ParseCIDR(addr)
if err != nil {
return err
}
routes, err := netlink.NetworkGetRoutes()
if err != nil {
return err
}
if err := checkRouteOverlaps(routes, dockerNetwork); err == nil {
if err := checkNameserverOverlaps(nameservers, dockerNetwork); err == nil {
ifaceAddr = addr
break
}
} else {
utils.Debugf("%s: %s", addr, err)
}
}
}
if ifaceAddr == "" {
return fmt.Errorf("Could not find a free IP address range for interface '%s'. Please configure its address manually and run 'docker -b %s'", config.BridgeIface, config.BridgeIface)
}
utils.Debugf("Creating bridge %s with network %s", config.BridgeIface, ifaceAddr)
if err := createBridgeIface(config.BridgeIface); err != nil {
return err
}
iface, err := net.InterfaceByName(config.BridgeIface)
if err != nil {
return err
}
ipAddr, ipNet, err := net.ParseCIDR(ifaceAddr)
if err != nil {
return err
}
if netlink.NetworkLinkAddIp(iface, ipAddr, ipNet); err != nil {
return fmt.Errorf("Unable to add private network: %s", err)
}
if err := netlink.NetworkLinkUp(iface); err != nil {
return fmt.Errorf("Unable to start network bridge: %s", err)
}
return nil
}
// Create the actual bridge device. This is more backward-compatible than
// netlink.NetworkLinkAdd and works on RHEL 6.
func createBridgeIface(name string) error {
s, err := syscall.Socket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_IP)
if err != nil {
utils.Debugf("Bridge socket creation failed IPv6 probably not enabled: %v", err)
s, err = syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_IP)
if err != nil {
return fmt.Errorf("Error creating bridge creation socket: %s", err)
}
}
defer syscall.Close(s)
nameBytePtr, err := syscall.BytePtrFromString(name)
if err != nil {
return fmt.Errorf("Error converting bridge name %s to byte array: %s", name, err)
}
if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, uintptr(s), siocBRADDBR, uintptr(unsafe.Pointer(nameBytePtr))); err != 0 {
return fmt.Errorf("Error creating bridge: %s", err)
}
return nil
}
// Return the IPv4 address of a network interface
func getIfaceAddr(name string) (net.Addr, error) {
iface, err := net.InterfaceByName(name)
if err != nil {
return nil, err
}
addrs, err := iface.Addrs()
if err != nil {
return nil, err
}
var addrs4 []net.Addr
for _, addr := range addrs {
ip := (addr.(*net.IPNet)).IP
if ip4 := ip.To4(); len(ip4) == net.IPv4len {
addrs4 = append(addrs4, addr)
}
}
switch {
case len(addrs4) == 0:
return nil, fmt.Errorf("Interface %v has no IP addresses", name)
case len(addrs4) > 1:
fmt.Printf("Interface %v has more than 1 IPv4 address. Defaulting to using %v\n",
name, (addrs4[0].(*net.IPNet)).IP)
}
return addrs4[0], nil
}
// Port mapper takes care of mapping external ports to containers by setting
// up iptables rules.
// It keeps track of all mappings and is able to unmap at will
type PortMapper struct {
tcpMapping map[string]*net.TCPAddr
tcpProxies map[string]proxy.Proxy
udpMapping map[string]*net.UDPAddr
udpProxies map[string]proxy.Proxy
iptables *iptables.Chain
defaultIp net.IP
proxyFactoryFunc func(net.Addr, net.Addr) (proxy.Proxy, error)
}
func (mapper *PortMapper) Map(ip net.IP, port int, backendAddr net.Addr) error {
mapKey := (&net.TCPAddr{Port: port, IP: ip}).String()
if _, exists := mapper.tcpProxies[mapKey]; exists {
return fmt.Errorf("Port %s is already in use", mapKey)
}
if _, isTCP := backendAddr.(*net.TCPAddr); isTCP {
backendPort := backendAddr.(*net.TCPAddr).Port
backendIP := backendAddr.(*net.TCPAddr).IP
if mapper.iptables != nil {
if err := mapper.iptables.Forward(iptables.Add, ip, port, "tcp", backendIP.String(), backendPort); err != nil {
return err
}
}
mapper.tcpMapping[mapKey] = backendAddr.(*net.TCPAddr)
proxy, err := mapper.proxyFactoryFunc(&net.TCPAddr{IP: ip, Port: port}, backendAddr)
if err != nil {
mapper.Unmap(ip, port, "tcp")
return err
}
mapper.tcpProxies[mapKey] = proxy
go proxy.Run()
} else {
backendPort := backendAddr.(*net.UDPAddr).Port
backendIP := backendAddr.(*net.UDPAddr).IP
if mapper.iptables != nil {
if err := mapper.iptables.Forward(iptables.Add, ip, port, "udp", backendIP.String(), backendPort); err != nil {
return err
}
}
mapper.udpMapping[mapKey] = backendAddr.(*net.UDPAddr)
proxy, err := mapper.proxyFactoryFunc(&net.UDPAddr{IP: ip, Port: port}, backendAddr)
if err != nil {
mapper.Unmap(ip, port, "udp")
return err
}
mapper.udpProxies[mapKey] = proxy
go proxy.Run()
}
return nil
}
func (mapper *PortMapper) Unmap(ip net.IP, port int, proto string) error {
mapKey := (&net.TCPAddr{Port: port, IP: ip}).String()
if proto == "tcp" {
backendAddr, ok := mapper.tcpMapping[mapKey]
if !ok {
return fmt.Errorf("Port tcp/%s is not mapped", mapKey)
}
if proxy, exists := mapper.tcpProxies[mapKey]; exists {
proxy.Close()
delete(mapper.tcpProxies, mapKey)
}
if mapper.iptables != nil {
if err := mapper.iptables.Forward(iptables.Delete, ip, port, proto, backendAddr.IP.String(), backendAddr.Port); err != nil {
return err
}
}
delete(mapper.tcpMapping, mapKey)
} else {
backendAddr, ok := mapper.udpMapping[mapKey]
if !ok {
return fmt.Errorf("Port udp/%s is not mapped", mapKey)
}
if proxy, exists := mapper.udpProxies[mapKey]; exists {
proxy.Close()
delete(mapper.udpProxies, mapKey)
}
if mapper.iptables != nil {
if err := mapper.iptables.Forward(iptables.Delete, ip, port, proto, backendAddr.IP.String(), backendAddr.Port); err != nil {
return err
}
}
delete(mapper.udpMapping, mapKey)
}
return nil
}
func newPortMapper(config *DaemonConfig) (*PortMapper, error) {
// We can always try removing the iptables
if err := iptables.RemoveExistingChain("DOCKER"); err != nil {
return nil, err
}
var chain *iptables.Chain
if config.EnableIptables {
var err error
chain, err = iptables.NewChain("DOCKER", config.BridgeIface)
if err != nil {
return nil, fmt.Errorf("Failed to create DOCKER chain: %s", err)
}
}
mapper := &PortMapper{
tcpMapping: make(map[string]*net.TCPAddr),
tcpProxies: make(map[string]proxy.Proxy),
udpMapping: make(map[string]*net.UDPAddr),
udpProxies: make(map[string]proxy.Proxy),
iptables: chain,
defaultIp: config.DefaultIp,
proxyFactoryFunc: proxy.NewProxy,
}
return mapper, nil
}
// Port allocator: Automatically allocate and release networking ports
type PortAllocator struct {
sync.Mutex
inUse map[string]struct{}
fountain chan int
quit chan bool
}
func (alloc *PortAllocator) runFountain() {
for {
for port := portRangeStart; port < portRangeEnd; port++ {
select {
case alloc.fountain <- port:
case quit := <-alloc.quit:
if quit {
return
}
}
}
}
}
// FIXME: Release can no longer fail, change its prototype to reflect that.
func (alloc *PortAllocator) Release(addr net.IP, port int) error {
mapKey := (&net.TCPAddr{Port: port, IP: addr}).String()
utils.Debugf("Releasing %d", port)
alloc.Lock()
delete(alloc.inUse, mapKey)
alloc.Unlock()
return nil
}
func (alloc *PortAllocator) Acquire(addr net.IP, port int) (int, error) {
mapKey := (&net.TCPAddr{Port: port, IP: addr}).String()
utils.Debugf("Acquiring %s", mapKey)
if port == 0 {
// Allocate a port from the fountain
for port := range alloc.fountain {
if _, err := alloc.Acquire(addr, port); err == nil {
return port, nil
}
}
return -1, fmt.Errorf("Port generator ended unexpectedly")
}
alloc.Lock()
defer alloc.Unlock()
if _, inUse := alloc.inUse[mapKey]; inUse {
return -1, fmt.Errorf("Port already in use: %d", port)
}
alloc.inUse[mapKey] = struct{}{}
return port, nil
}
func (alloc *PortAllocator) Close() error {
alloc.quit <- true
close(alloc.quit)
close(alloc.fountain)
return nil
}
func newPortAllocator() (*PortAllocator, error) {
allocator := &PortAllocator{
inUse: make(map[string]struct{}),
fountain: make(chan int),
quit: make(chan bool),
}
go allocator.runFountain()
return allocator, nil
}
// IP allocator: Automatically allocate and release networking ports
type IPAllocator struct {
network *net.IPNet
queueAlloc chan allocatedIP
queueReleased chan net.IP
inUse map[int32]struct{}
quit chan bool
}
type allocatedIP struct {
ip net.IP
err error
}
func (alloc *IPAllocator) run() {
firstIP, _ := networkRange(alloc.network)
ipNum := ipToInt(firstIP)
ownIP := ipToInt(alloc.network.IP)
size := networkSize(alloc.network.Mask)
pos := int32(1)
max := size - 2 // -1 for the broadcast address, -1 for the gateway address
for {
var (
newNum int32
inUse bool
)
// Find first unused IP, give up after one whole round
for attempt := int32(0); attempt < max; attempt++ {
newNum = ipNum + pos
pos = pos%max + 1
// The network's IP is never okay to use
if newNum == ownIP {
continue
}
if _, inUse = alloc.inUse[newNum]; !inUse {
// We found an unused IP
break
}
}
ip := allocatedIP{ip: intToIP(newNum)}
if inUse {
ip.err = errors.New("No unallocated IP available")
}
select {
case quit := <-alloc.quit:
if quit {
return
}
case alloc.queueAlloc <- ip:
alloc.inUse[newNum] = struct{}{}
case released := <-alloc.queueReleased:
r := ipToInt(released)
delete(alloc.inUse, r)
if inUse {
// If we couldn't allocate a new IP, the released one
// will be the only free one now, so instantly use it
// next time
pos = r - ipNum
} else {
// Use same IP as last time
if pos == 1 {
pos = max
} else {
pos--
}
}
}
}
}
func (alloc *IPAllocator) Acquire() (net.IP, error) {
ip := <-alloc.queueAlloc
return ip.ip, ip.err
}
func (alloc *IPAllocator) Release(ip net.IP) {
alloc.queueReleased <- ip
}
func (alloc *IPAllocator) Close() error {
alloc.quit <- true
close(alloc.quit)
close(alloc.queueAlloc)
close(alloc.queueReleased)
return nil
}
func newIPAllocator(network *net.IPNet) *IPAllocator {
alloc := &IPAllocator{
network: network,
queueAlloc: make(chan allocatedIP),
queueReleased: make(chan net.IP),
inUse: make(map[int32]struct{}),
quit: make(chan bool),
}
go alloc.run()
return alloc
}
// Network interface represents the networking stack of a container
type NetworkInterface struct {
IPNet net.IPNet
Gateway net.IP
manager *NetworkManager
extPorts []*Nat
disabled bool
}
// Allocate an external port and map it to the interface
func (iface *NetworkInterface) AllocatePort(port Port, binding PortBinding) (*Nat, error) {
if iface.disabled {
return nil, fmt.Errorf("Trying to allocate port for interface %v, which is disabled", iface) // FIXME
}
ip := iface.manager.portMapper.defaultIp
if binding.HostIp != "" {
ip = net.ParseIP(binding.HostIp)
} else {
binding.HostIp = ip.String()
}
nat := &Nat{
Port: port,
Binding: binding,
}
containerPort, err := parsePort(port.Port())
if err != nil {
return nil, err
}
hostPort, _ := parsePort(nat.Binding.HostPort)
if nat.Port.Proto() == "tcp" {
extPort, err := iface.manager.tcpPortAllocator.Acquire(ip, hostPort)
if err != nil {
return nil, err
}
backend := &net.TCPAddr{IP: iface.IPNet.IP, Port: containerPort}
if err := iface.manager.portMapper.Map(ip, extPort, backend); err != nil {
iface.manager.tcpPortAllocator.Release(ip, extPort)
return nil, err
}
nat.Binding.HostPort = strconv.Itoa(extPort)
} else {
extPort, err := iface.manager.udpPortAllocator.Acquire(ip, hostPort)
if err != nil {
return nil, err
}
backend := &net.UDPAddr{IP: iface.IPNet.IP, Port: containerPort}
if err := iface.manager.portMapper.Map(ip, extPort, backend); err != nil {
iface.manager.udpPortAllocator.Release(ip, extPort)
return nil, err
}
nat.Binding.HostPort = strconv.Itoa(extPort)
}
iface.extPorts = append(iface.extPorts, nat)
return nat, nil
}
type Nat struct {
Port Port
Binding PortBinding
}
func (n *Nat) String() string {
return fmt.Sprintf("%s:%s:%s/%s", n.Binding.HostIp, n.Binding.HostPort, n.Port.Port(), n.Port.Proto())
}
// Release: Network cleanup - release all resources
func (iface *NetworkInterface) Release() {
if iface.disabled {
return
}
for _, nat := range iface.extPorts {
hostPort, err := parsePort(nat.Binding.HostPort)
if err != nil {
log.Printf("Unable to get host port: %s", err)
continue
}
ip := net.ParseIP(nat.Binding.HostIp)
utils.Debugf("Unmaping %s/%s:%s", nat.Port.Proto, ip.String(), nat.Binding.HostPort)
if err := iface.manager.portMapper.Unmap(ip, hostPort, nat.Port.Proto()); err != nil {
log.Printf("Unable to unmap port %s: %s", nat, err)
}
if nat.Port.Proto() == "tcp" {
if err := iface.manager.tcpPortAllocator.Release(ip, hostPort); err != nil {
log.Printf("Unable to release port %s", nat)
}
} else if nat.Port.Proto() == "udp" {
if err := iface.manager.udpPortAllocator.Release(ip, hostPort); err != nil {
log.Printf("Unable to release port %s: %s", nat, err)
}
}
}
iface.manager.ipAllocator.Release(iface.IPNet.IP)
}
// Network Manager manages a set of network interfaces
// Only *one* manager per host machine should be used
type NetworkManager struct {
bridgeIface string
bridgeNetwork *net.IPNet
ipAllocator *IPAllocator
tcpPortAllocator *PortAllocator
udpPortAllocator *PortAllocator
portMapper *PortMapper
disabled bool
}
// Allocate a network interface
func (manager *NetworkManager) Allocate() (*NetworkInterface, error) {
if manager.disabled {
return &NetworkInterface{disabled: true}, nil
}
var ip net.IP
var err error
ip, err = manager.ipAllocator.Acquire()
if err != nil {
return nil, err
}
// avoid duplicate IP
ipNum := ipToInt(ip)
firstIP := manager.ipAllocator.network.IP.To4().Mask(manager.ipAllocator.network.Mask)
firstIPNum := ipToInt(firstIP) + 1
if firstIPNum == ipNum {
ip, err = manager.ipAllocator.Acquire()
if err != nil {
return nil, err
}
}
iface := &NetworkInterface{
IPNet: net.IPNet{IP: ip, Mask: manager.bridgeNetwork.Mask},
Gateway: manager.bridgeNetwork.IP,
manager: manager,
}
return iface, nil
}
func (manager *NetworkManager) Close() error {
if manager.disabled {
return nil
}
err1 := manager.tcpPortAllocator.Close()
err2 := manager.udpPortAllocator.Close()
err3 := manager.ipAllocator.Close()
if err1 != nil {
return err1
}
if err2 != nil {
return err2
}
return err3
}
func newNetworkManager(config *DaemonConfig) (*NetworkManager, error) {
if config.BridgeIface == DisableNetworkBridge {
manager := &NetworkManager{
disabled: true,
}
return manager, nil
}
addr, err := getIfaceAddr(config.BridgeIface)
if err != nil {
// If the iface is not found, try to create it
if err := CreateBridgeIface(config); err != nil {
return nil, err
}
addr, err = getIfaceAddr(config.BridgeIface)
if err != nil {
return nil, err
}
}
network := addr.(*net.IPNet)
// Configure iptables for link support
if config.EnableIptables {
// Enable NAT
natArgs := []string{"POSTROUTING", "-t", "nat", "-s", addr.String(), "!", "-d", addr.String(), "-j", "MASQUERADE"}
if !iptables.Exists(natArgs...) {
if output, err := iptables.Raw(append([]string{"-A"}, natArgs...)...); err != nil {
return nil, fmt.Errorf("Unable to enable network bridge NAT: %s", err)
} else if len(output) != 0 {
return nil, fmt.Errorf("Error iptables postrouting: %s", output)
}
}
// Accept incoming packets for existing connections
existingArgs := []string{"FORWARD", "-o", config.BridgeIface, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"}
if !iptables.Exists(existingArgs...) {
if output, err := iptables.Raw(append([]string{"-I"}, existingArgs...)...); err != nil {
return nil, fmt.Errorf("Unable to allow incoming packets: %s", err)
} else if len(output) != 0 {
return nil, fmt.Errorf("Error iptables allow incoming: %s", output)
}
}
// Accept all non-intercontainer outgoing packets
outgoingArgs := []string{"FORWARD", "-i", config.BridgeIface, "!", "-o", config.BridgeIface, "-j", "ACCEPT"}
if !iptables.Exists(outgoingArgs...) {
if output, err := iptables.Raw(append([]string{"-I"}, outgoingArgs...)...); err != nil {
return nil, fmt.Errorf("Unable to allow outgoing packets: %s", err)
} else if len(output) != 0 {
return nil, fmt.Errorf("Error iptables allow outgoing: %s", output)
}
}
args := []string{"FORWARD", "-i", config.BridgeIface, "-o", config.BridgeIface, "-j"}
acceptArgs := append(args, "ACCEPT")
dropArgs := append(args, "DROP")
if !config.InterContainerCommunication {
iptables.Raw(append([]string{"-D"}, acceptArgs...)...)
if !iptables.Exists(dropArgs...) {
utils.Debugf("Disable inter-container communication")
if output, err := iptables.Raw(append([]string{"-I"}, dropArgs...)...); err != nil {
return nil, fmt.Errorf("Unable to prevent intercontainer communication: %s", err)
} else if len(output) != 0 {
return nil, fmt.Errorf("Error disabling intercontainer communication: %s", output)
}
}
} else {
iptables.Raw(append([]string{"-D"}, dropArgs...)...)
if !iptables.Exists(acceptArgs...) {
utils.Debugf("Enable inter-container communication")
if output, err := iptables.Raw(append([]string{"-I"}, acceptArgs...)...); err != nil {
return nil, fmt.Errorf("Unable to allow intercontainer communication: %s", err)
} else if len(output) != 0 {
return nil, fmt.Errorf("Error enabling intercontainer communication: %s", output)
}
}
}
}
ipAllocator := newIPAllocator(network)
tcpPortAllocator, err := newPortAllocator()
if err != nil {
return nil, err
}
udpPortAllocator, err := newPortAllocator()
if err != nil {
return nil, err
}
portMapper, err := newPortMapper(config)
if err != nil {
return nil, err
}
manager := &NetworkManager{
bridgeIface: config.BridgeIface,
bridgeNetwork: network,
ipAllocator: ipAllocator,
tcpPortAllocator: tcpPortAllocator,
udpPortAllocator: udpPortAllocator,
portMapper: portMapper,
}
return manager, nil
}