func pickLocalAddr(laddrs []ma.Multiaddr, raddr ma.Multiaddr) (laddr ma.Multiaddr) {
if len(laddrs) < 1 {
return nil
}
// make sure that we ONLY use local addrs that match the remote addr.
laddrs = manet.AddrMatch(raddr, laddrs)
if len(laddrs) < 1 {
return nil
}
// make sure that we ONLY use local addrs that CAN dial the remote addr.
// filter out all the local addrs that aren't capable
raddrIPLayer := ma.Split(raddr)[0]
raddrIsLoopback := manet.IsIPLoopback(raddrIPLayer)
raddrIsLinkLocal := manet.IsIP6LinkLocal(raddrIPLayer)
laddrs = addrutil.FilterAddrs(laddrs, func(a ma.Multiaddr) bool {
laddrIPLayer := ma.Split(a)[0]
laddrIsLoopback := manet.IsIPLoopback(laddrIPLayer)
laddrIsLinkLocal := manet.IsIP6LinkLocal(laddrIPLayer)
if laddrIsLoopback { // our loopback addrs can only dial loopbacks.
return raddrIsLoopback
}
if laddrIsLinkLocal {
return raddrIsLinkLocal // out linklocal addrs can only dial link locals.
}
return true
})
// TODO pick with a good heuristic
// we use a random one for now to prevent bad addresses from making nodes unreachable
// with a random selection, multiple tries may work.
return laddrs[rand.Intn(len(laddrs))]
}
// Builds and returns the Multiaddrs for the swarm to listen on
func BuildSwarmAddrs(port int) [][]byte {
// Get all interface addresses
all, _ := manet.InterfaceMultiaddrs()
// Filter out loopback and link-local addresses
var filtered []ma.Multiaddr
for _, m := range all {
if manet.IsIPLoopback(m) {
continue
}
if manet.IsIP6LinkLocal(m) {
continue
}
filtered = append(filtered, m)
}
// Add tcp/<port> to each address and convert to byte representation
prt, err := ma.NewMultiaddr(fmt.Sprintf("/tcp/%d", port))
if err != nil {
panic(err)
}
var listenAddrs [][]byte
for _, a := range filtered {
listenAddrs = append(listenAddrs, a.Encapsulate(prt).Bytes())
}
return listenAddrs
}
// AddrOverNonLocalIP returns whether the addr uses a non-local ip link
func AddrOverNonLocalIP(a ma.Multiaddr) bool {
split := ma.Split(a)
if len(split) < 1 {
return false
}
if manet.IsIP6LinkLocal(split[0]) {
return false
}
return true
}
// AddrIsShareableOnWAN returns whether the given address should be shareable on the
// wide area network (wide internet).
func AddrIsShareableOnWAN(addr ma.Multiaddr) bool {
s := ma.Split(addr)
if len(s) < 1 {
return false
}
a := s[0]
if manet.IsIPLoopback(a) || manet.IsIP6LinkLocal(a) || manet.IsIPUnspecified(a) {
return false
}
return manet.IsThinWaist(a)
}
func TestInterfaceAddrs(t *testing.T) {
addrs, err := InterfaceAddresses()
if err != nil {
t.Fatal(err)
}
if len(addrs) < 1 {
t.Error("no addresses")
}
for _, a := range addrs {
if manet.IsIP6LinkLocal(a) {
t.Error("should not return ip link local addresses", a)
}
}
if len(addrs) < 1 {
t.Error("no good interface addrs")
}
}