p2p/nat: new package for port mapping stuff

I have verified that UPnP and NAT-PMP work against an older version of
the MiniUPnP daemon running on pfSense. This code is kind of hard to
test automatically.
This commit is contained in:
Felix Lange 2015-02-10 23:49:45 +01:00
parent 4242b05462
commit 1543833ca0
3 changed files with 499 additions and 0 deletions

235
p2p/nat/nat.go Normal file
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// Package nat provides access to common port mapping protocols.
package nat
import (
"errors"
"fmt"
"net"
"strings"
"sync"
"time"
"github.com/ethereum/go-ethereum/logger"
"github.com/jackpal/go-nat-pmp"
)
var log = logger.NewLogger("P2P NAT")
// An implementation of nat.Interface can map local ports to ports
// accessible from the Internet.
type Interface interface {
// These methods manage a mapping between a port on the local
// machine to a port that can be connected to from the internet.
//
// protocol is "UDP" or "TCP". Some implementations allow setting
// a display name for the mapping. The mapping may be removed by
// the gateway when its lifetime ends.
AddMapping(protocol string, extport, intport int, name string, lifetime time.Duration) error
DeleteMapping(protocol string, extport, intport int) error
// This method should return the external (Internet-facing)
// address of the gateway device.
ExternalIP() (net.IP, error)
// Should return name of the method. This is used for logging.
String() string
}
// Parse parses a NAT interface description.
// The following formats are currently accepted.
// Note that mechanism names are not case-sensitive.
//
// "" or "none" return nil
// "extip:77.12.33.4" will assume the local machine is reachable on the given IP
// "any" uses the first auto-detected mechanism
// "upnp" uses the Universal Plug and Play protocol
// "pmp" uses NAT-PMP with an auto-detected gateway address
// "pmp:192.168.0.1" uses NAT-PMP with the given gateway address
func Parse(spec string) (Interface, error) {
var (
parts = strings.SplitN(spec, ":", 2)
mech = strings.ToLower(parts[0])
ip net.IP
)
if len(parts) > 1 {
ip = net.ParseIP(parts[1])
if ip == nil {
return nil, errors.New("invalid IP address")
}
}
switch mech {
case "", "none", "off":
return nil, nil
case "any", "auto", "on":
return Any(), nil
case "extip", "ip":
if ip == nil {
return nil, errors.New("missing IP address")
}
return ExtIP(ip), nil
case "upnp":
return UPnP(), nil
case "pmp", "natpmp", "nat-pmp":
return PMP(ip), nil
default:
return nil, fmt.Errorf("unknown mechanism %q", parts[0])
}
}
const (
mapTimeout = 20 * time.Minute
mapUpdateInterval = 15 * time.Minute
)
// Map adds a port mapping on m and keeps it alive until c is closed.
// This function is typically invoked in its own goroutine.
func Map(m Interface, c chan struct{}, protocol string, extport, intport int, name string) {
refresh := time.NewTimer(mapUpdateInterval)
defer func() {
refresh.Stop()
log.Debugf("Deleting port mapping: %s %d -> %d (%s) using %s\n", protocol, extport, intport, name, m)
m.DeleteMapping(protocol, extport, intport)
}()
log.Debugf("add mapping: %s %d -> %d (%s) using %s\n", protocol, extport, intport, name, m)
if err := m.AddMapping(protocol, intport, extport, name, mapTimeout); err != nil {
log.Errorf("mapping error: %v\n", err)
}
for {
select {
case _, ok := <-c:
if !ok {
return
}
case <-refresh.C:
log.DebugDetailf("refresh mapping: %s %d -> %d (%s) using %s\n", protocol, extport, intport, name, m)
if err := m.AddMapping(protocol, intport, extport, name, mapTimeout); err != nil {
log.Errorf("mapping error: %v\n", err)
}
refresh.Reset(mapUpdateInterval)
}
}
}
// ExtIP assumes that the local machine is reachable on the given
// external IP address, and that any required ports were mapped manually.
// Mapping operations will not return an error but won't actually do anything.
func ExtIP(ip net.IP) Interface {
if ip == nil {
panic("IP must not be nil")
}
return extIP(ip)
}
type extIP net.IP
func (n extIP) ExternalIP() (net.IP, error) { return net.IP(n), nil }
func (n extIP) String() string { return fmt.Sprintf("ExtIP(%v)", net.IP(n)) }
// These do nothing.
func (extIP) AddMapping(string, int, int, string, time.Duration) error { return nil }
func (extIP) DeleteMapping(string, int, int) error { return nil }
// Any returns a port mapper that tries to discover any supported
// mechanism on the local network.
func Any() Interface {
// TODO: attempt to discover whether the local machine has an
// Internet-class address. Return ExtIP in this case.
return startautodisc("UPnP or NAT-PMP", func() Interface {
found := make(chan Interface, 2)
go func() { found <- discoverUPnP() }()
go func() { found <- discoverPMP() }()
for i := 0; i < cap(found); i++ {
if c := <-found; c != nil {
return c
}
}
return nil
})
}
// UPnP returns a port mapper that uses UPnP. It will attempt to
// discover the address of your router using UDP broadcasts.
func UPnP() Interface {
return startautodisc("UPnP", discoverUPnP)
}
// PMP returns a port mapper that uses NAT-PMP. The provided gateway
// address should be the IP of your router. If the given gateway
// address is nil, PMP will attempt to auto-discover the router.
func PMP(gateway net.IP) Interface {
if gateway != nil {
return &pmp{gw: gateway, c: natpmp.NewClient(gateway)}
}
return startautodisc("NAT-PMP", discoverPMP)
}
// autodisc represents a port mapping mechanism that is still being
// auto-discovered. Calls to the Interface methods on this type will
// wait until the discovery is done and then call the method on the
// discovered mechanism.
//
// This type is useful because discovery can take a while but we
// want return an Interface value from UPnP, PMP and Auto immediately.
type autodisc struct {
what string
done <-chan Interface
mu sync.Mutex
found Interface
}
func startautodisc(what string, doit func() Interface) Interface {
// TODO: monitor network configuration and rerun doit when it changes.
done := make(chan Interface)
ad := &autodisc{what: what, done: done}
go func() { done <- doit(); close(done) }()
return ad
}
func (n *autodisc) AddMapping(protocol string, extport, intport int, name string, lifetime time.Duration) error {
if err := n.wait(); err != nil {
return err
}
return n.found.AddMapping(protocol, extport, intport, name, lifetime)
}
func (n *autodisc) DeleteMapping(protocol string, extport, intport int) error {
if err := n.wait(); err != nil {
return err
}
return n.found.DeleteMapping(protocol, extport, intport)
}
func (n *autodisc) ExternalIP() (net.IP, error) {
if err := n.wait(); err != nil {
return nil, err
}
return n.found.ExternalIP()
}
func (n *autodisc) String() string {
n.mu.Lock()
defer n.mu.Unlock()
if n.found == nil {
return n.what
} else {
return n.found.String()
}
}
func (n *autodisc) wait() error {
n.mu.Lock()
found := n.found
n.mu.Unlock()
if found != nil {
// already discovered
return nil
}
if found = <-n.done; found == nil {
return errors.New("no devices discovered")
}
n.mu.Lock()
n.found = found
n.mu.Unlock()
return nil
}

115
p2p/nat/natpmp.go Normal file
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package nat
import (
"fmt"
"net"
"strings"
"time"
"github.com/jackpal/go-nat-pmp"
)
// natPMPClient adapts the NAT-PMP protocol implementation so it conforms to
// the common interface.
type pmp struct {
gw net.IP
c *natpmp.Client
}
func (n *pmp) String() string {
return fmt.Sprintf("NAT-PMP(%v)", n.gw)
}
func (n *pmp) ExternalIP() (net.IP, error) {
response, err := n.c.GetExternalAddress()
if err != nil {
return nil, err
}
return response.ExternalIPAddress[:], nil
}
func (n *pmp) AddMapping(protocol string, extport, intport int, name string, lifetime time.Duration) error {
if lifetime <= 0 {
return fmt.Errorf("lifetime must not be <= 0")
}
// Note order of port arguments is switched between our
// AddMapping and the client's AddPortMapping.
_, err := n.c.AddPortMapping(strings.ToLower(protocol), intport, extport, int(lifetime/time.Second))
return err
}
func (n *pmp) DeleteMapping(protocol string, extport, intport int) (err error) {
// To destroy a mapping, send an add-port with an internalPort of
// the internal port to destroy, an external port of zero and a
// time of zero.
_, err = n.c.AddPortMapping(strings.ToLower(protocol), intport, 0, 0)
return err
}
func discoverPMP() Interface {
// run external address lookups on all potential gateways
gws := potentialGateways()
found := make(chan *pmp, len(gws))
for i := range gws {
gw := gws[i]
go func() {
c := natpmp.NewClient(gw)
if _, err := c.GetExternalAddress(); err != nil {
found <- nil
} else {
found <- &pmp{gw, c}
}
}()
}
// return the one that responds first.
// discovery needs to be quick, so we stop caring about
// any responses after a very short timeout.
timeout := time.NewTimer(1 * time.Second)
defer timeout.Stop()
for _ = range gws {
select {
case c := <-found:
if c != nil {
return c
}
case <-timeout.C:
return nil
}
}
return nil
}
var (
// LAN IP ranges
_, lan10, _ = net.ParseCIDR("10.0.0.0/8")
_, lan176, _ = net.ParseCIDR("172.16.0.0/12")
_, lan192, _ = net.ParseCIDR("192.168.0.0/16")
)
// TODO: improve this. We currently assume that (on most networks)
// the router is X.X.X.1 in a local LAN range.
func potentialGateways() (gws []net.IP) {
ifaces, err := net.Interfaces()
if err != nil {
return nil
}
for _, iface := range ifaces {
ifaddrs, err := iface.Addrs()
if err != nil {
return gws
}
for _, addr := range ifaddrs {
switch x := addr.(type) {
case *net.IPNet:
if lan10.Contains(x.IP) || lan176.Contains(x.IP) || lan192.Contains(x.IP) {
ip := x.IP.Mask(x.Mask).To4()
if ip != nil {
ip[3] = ip[3] | 0x01
gws = append(gws, ip)
}
}
}
}
}
return gws
}

149
p2p/nat/natupnp.go Normal file
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package nat
import (
"errors"
"fmt"
"net"
"strings"
"time"
"github.com/fjl/goupnp"
"github.com/fjl/goupnp/dcps/internetgateway1"
"github.com/fjl/goupnp/dcps/internetgateway2"
)
type upnp struct {
dev *goupnp.RootDevice
service string
client upnpClient
}
type upnpClient interface {
GetExternalIPAddress() (string, error)
AddPortMapping(string, uint16, string, uint16, string, bool, string, uint32) error
DeletePortMapping(string, uint16, string) error
GetNATRSIPStatus() (sip bool, nat bool, err error)
}
func (n *upnp) ExternalIP() (addr net.IP, err error) {
ipString, err := n.client.GetExternalIPAddress()
if err != nil {
return nil, err
}
ip := net.ParseIP(ipString)
if ip == nil {
return nil, errors.New("bad IP in response")
}
return ip, nil
}
func (n *upnp) AddMapping(protocol string, extport, intport int, desc string, lifetime time.Duration) error {
ip, err := n.internalAddress()
if err != nil {
return nil
}
protocol = strings.ToUpper(protocol)
lifetimeS := uint32(lifetime / time.Second)
return n.client.AddPortMapping("", uint16(extport), protocol, uint16(intport), ip.String(), true, desc, lifetimeS)
}
func (n *upnp) internalAddress() (net.IP, error) {
devaddr, err := net.ResolveUDPAddr("udp4", n.dev.URLBase.Host)
if err != nil {
return nil, err
}
ifaces, err := net.Interfaces()
if err != nil {
return nil, err
}
for _, iface := range ifaces {
addrs, err := iface.Addrs()
if err != nil {
return nil, err
}
for _, addr := range addrs {
switch x := addr.(type) {
case *net.IPNet:
if x.Contains(devaddr.IP) {
return x.IP, nil
}
}
}
}
return nil, fmt.Errorf("could not find local address in same net as %v", devaddr)
}
func (n *upnp) DeleteMapping(protocol string, extport, intport int) error {
return n.client.DeletePortMapping("", uint16(extport), strings.ToUpper(protocol))
}
func (n *upnp) String() string {
return "UPNP " + n.service
}
// discoverUPnP searches for Internet Gateway Devices
// and returns the first one it can find on the local network.
func discoverUPnP() Interface {
found := make(chan *upnp, 2)
// IGDv1
go discover(found, internetgateway1.URN_WANConnectionDevice_1, func(dev *goupnp.RootDevice, sc goupnp.ServiceClient) *upnp {
switch sc.Service.ServiceType {
case internetgateway1.URN_WANIPConnection_1:
return &upnp{dev, "IGDv1-IP1", &internetgateway1.WANIPConnection1{sc}}
case internetgateway1.URN_WANPPPConnection_1:
return &upnp{dev, "IGDv1-PPP1", &internetgateway1.WANPPPConnection1{sc}}
}
return nil
})
// IGDv2
go discover(found, internetgateway2.URN_WANConnectionDevice_2, func(dev *goupnp.RootDevice, sc goupnp.ServiceClient) *upnp {
switch sc.Service.ServiceType {
case internetgateway2.URN_WANIPConnection_1:
return &upnp{dev, "IGDv2-IP1", &internetgateway2.WANIPConnection1{sc}}
case internetgateway2.URN_WANIPConnection_2:
return &upnp{dev, "IGDv2-IP2", &internetgateway2.WANIPConnection2{sc}}
case internetgateway2.URN_WANPPPConnection_1:
return &upnp{dev, "IGDv2-PPP1", &internetgateway2.WANPPPConnection1{sc}}
}
return nil
})
for i := 0; i < cap(found); i++ {
if c := <-found; c != nil {
return c
}
}
return nil
}
func discover(out chan<- *upnp, target string, matcher func(*goupnp.RootDevice, goupnp.ServiceClient) *upnp) {
devs, err := goupnp.DiscoverDevices(target)
if err != nil {
return
}
found := false
for i := 0; i < len(devs) && !found; i++ {
if devs[i].Root == nil {
continue
}
devs[i].Root.Device.VisitServices(func(service *goupnp.Service) {
if found {
return
}
// check for a matching IGD service
sc := goupnp.ServiceClient{service.NewSOAPClient(), devs[i].Root, service}
upnp := matcher(devs[i].Root, sc)
if upnp == nil {
return
}
// check whether port mapping is enabled
if _, nat, err := upnp.client.GetNATRSIPStatus(); err != nil || !nat {
return
}
out <- upnp
found = true
})
}
if !found {
out <- nil
}
}