// createPortMapping creates a NAT port mapping, or nil if none requested or found.
func CreatePortMapping(flags *TorrentFlags) (nat NAT, err error) {
if flags.UseUPnP && flags.UseNATPMP {
err = fmt.Errorf("Cannot specify both -useUPnP and -useNATPMP")
return
}
if flags.UseUPnP {
log.Println("Using UPnP to open port.")
nat, err = Discover()
}
if flags.UseNATPMP {
var gatewayIP net.IP
if flags.Gateway == "" {
log.Printf("useNATPMP but gateway not provided, trying discovery")
gatewayIP, err = gateway.DiscoverGateway()
if err != nil {
return
}
log.Printf("...discovered gateway IP: %s", gatewayIP)
} else {
gatewayIP = net.ParseIP(flags.Gateway)
}
log.Println("Using NAT-PMP to open port.")
if gatewayIP == nil {
err = fmt.Errorf("Could not parse gateway %q", flags.Gateway)
}
nat = NewNatPMP(gatewayIP)
}
return
}
// 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 {
if iface.Flags == net.FlagLoopback {
continue
}
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)
}
}
}
}
}
wip, err := gateway.DiscoverGateway()
if err == nil {
gws = append(gws, wip)
}
return gws
}
// Create a NAT-PMP client for the NAT-PMP server at the default gateway.
func NewClientForDefaultGateway(timeout time.Duration) (nat *Client, err error) {
var g net.IP
g, err = gateway.DiscoverGateway()
if err != nil {
return
}
nat = NewClient(g, timeout)
return
}
// Create a NAT-PMP client for the NAT-PMP server at the default gateway.
func NewClientForDefaultGateway() (nat *Client, err error) {
var g net.IP
g, err = gateway.DiscoverGateway()
if err != nil {
return
}
nat = NewClient(g)
return
}
func discoverNATPMP() <-chan NAT {
res := make(chan NAT, 1)
ip, err := gateway.DiscoverGateway()
if err == nil {
go discoverNATPMPWithAddr(res, ip)
}
return res
}
func Discover(renewal, timeout time.Duration) []nat.Device {
ip, err := gateway.DiscoverGateway()
if err != nil {
l.Debugln("Failed to discover gateway", err)
return nil
}
if ip == nil || ip.IsUnspecified() {
return nil
}
l.Debugln("Discovered gateway at", ip)
c := natpmp.NewClient(ip, timeout)
// Try contacting the gateway, if it does not respond, assume it does not
// speak NAT-PMP.
_, err = c.GetExternalAddress()
if err != nil && strings.Contains(err.Error(), "Timed out") {
l.Debugln("Timeout trying to get external address, assume no NAT-PMP available")
return nil
}
var localIP net.IP
// Port comes from the natpmp package
conn, err := net.DialTimeout("udp", net.JoinHostPort(ip.String(), "5351"), timeout)
if err == nil {
conn.Close()
localIPAddress, _, err := net.SplitHostPort(conn.LocalAddr().String())
if err == nil {
localIP = net.ParseIP(localIPAddress)
} else {
l.Debugln("Failed to lookup local IP", err)
}
}
return []nat.Device{&wrapper{
renewal: renewal,
localIP: localIP,
gatewayIP: ip,
client: c,
}}
}