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package eth
import (
"fmt"
"net"
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.
type natPMPClient struct {
client *natpmp.Client
}
func NewNatPMP(gateway net.IP) (nat NAT) {
return &natPMPClient{natpmp.NewClient(gateway)}
}
func (n *natPMPClient) GetExternalAddress() (addr net.IP, err error) {
response, err := n.client.GetExternalAddress()
if err != nil {
return
}
ip := response.ExternalIPAddress
addr = net.IPv4(ip[0], ip[1], ip[2], ip[3])
return
}
func (n *natPMPClient) AddPortMapping(protocol string, externalPort, internalPort int,
description string, timeout int) (mappedExternalPort int, err error) {
if timeout <= 0 {
err = fmt.Errorf("timeout must not be <= 0")
return
}
// Note order of port arguments is switched between our AddPortMapping and the client's AddPortMapping.
response, err := n.client.AddPortMapping(protocol, internalPort, externalPort, timeout)
if err != nil {
return
}
mappedExternalPort = int(response.MappedExternalPort)
return
}
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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