From 1543833ca0b920d38e98994367f3871867d66781 Mon Sep 17 00:00:00 2001 From: Felix Lange Date: Tue, 10 Feb 2015 23:49:45 +0100 Subject: 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. --- p2p/nat/nat.go | 235 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 235 insertions(+) create mode 100644 p2p/nat/nat.go (limited to 'p2p/nat/nat.go') diff --git a/p2p/nat/nat.go b/p2p/nat/nat.go new file mode 100644 index 000000000..12d355ba1 --- /dev/null +++ b/p2p/nat/nat.go @@ -0,0 +1,235 @@ +// 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 +} -- cgit