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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
}
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