1 files changed, 55 insertions, 0 deletions
diff --git a/p2p/natpmp.go b/p2p/natpmp.go
new file mode 100644
index 000000000..6714678c4
--- /dev/null
+++ b/p2p/natpmp.go
@@ -0,0 +1,55 @@
+package p2p
+
+import (
+	"fmt"
+	"net"
+	"time"
+
+	natpmp "github.com/jackpal/go-nat-pmp"
+)
+
+// Adapt the NAT-PMP protocol to the NAT interface
+
+// TODO:
+//  + Register for changes to the external address.
+//  + Re-register port mapping when router reboots.
+//  + A mechanism for keeping a port mapping registered.
+//  + Discover gateway address automatically.
+
+type natPMPClient struct {
+	client *natpmp.Client
+}
+
+// PMP returns a NAT traverser that uses NAT-PMP. The provided gateway
+// address should be the IP of your router.
+func PMP(gateway net.IP) (nat NAT) {
+	return &natPMPClient{natpmp.NewClient(gateway)}
+}
+
+func (*natPMPClient) String() string {
+	return "NAT-PMP"
+}
+
+func (n *natPMPClient) GetExternalAddress() (net.IP, error) {
+	response, err := n.client.GetExternalAddress()
+	if err != nil {
+		return nil, err
+	}
+	return response.ExternalIPAddress[:], nil
+}
+
+func (n *natPMPClient) AddPortMapping(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 AddPortMapping and the client's AddPortMapping.
+	_, err := n.client.AddPortMapping(protocol, intport, extport, int(lifetime/time.Second))
+	return err
+}
+
+func (n *natPMPClient) DeletePortMapping(protocol string, externalPort, internalPort 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.client.AddPortMapping(protocol, internalPort, 0, 0)
+	return
+}