autorelay: curtail addrsplosion

p2p/host/relay/addrsplosion.go

@@ -0,0 +1,167 @@
+package relay
+
+import (
+	"encoding/binary"
+
+	circuit "github.com/libp2p/go-libp2p-circuit"
+	ma "github.com/multiformats/go-multiaddr"
+	dns "github.com/multiformats/go-multiaddr-dns"
+	manet "github.com/multiformats/go-multiaddr-net"
+)
+
+// This function cleans up a relay's address set to remove private addresses and curtail
+// addrsplosion.
+func cleanupAddressSet(addrs []ma.Multiaddr) []ma.Multiaddr {
+	var public, private []ma.Multiaddr
+
+	for _, a := range addrs {
+		if isRelayAddr(a) {
+			continue
+		}
+
+		if manet.IsPublicAddr(a) || isDNSAddr(a) {
+			public = append(public, a)
+			continue
+		}
+
+		// discard unroutable addrs
+		if manet.IsPrivateAddr(a) {
+			private = append(private, a)
+		}
+	}
+
+	if !hasAddrsplosion(public) {
+		return public
+	}
+
+	return sanitizeAddrsplodedSet(public, private)
+}
+
+func isRelayAddr(a ma.Multiaddr) bool {
+	isRelay := false
+
+	ma.ForEach(a, func(c ma.Component) bool {
+		switch c.Protocol().Code {
+		case circuit.P_CIRCUIT:
+			isRelay = true
+			return false
+		default:
+			return true
+		}
+	})
+
+	return isRelay
+}
+
+func isDNSAddr(a ma.Multiaddr) bool {
+	if first, _ := ma.SplitFirst(a); first != nil {
+		switch first.Protocol().Code {
+		case dns.P_DNS4, dns.P_DNS6, dns.P_DNSADDR:
+			return true
+		}
+	}
+	return false
+}
+
+// we have addrsplosion if for some protocol we advertise multiple ports on
+// the same base address.
+func hasAddrsplosion(addrs []ma.Multiaddr) bool {
+	aset := make(map[string]int)
+
+	for _, a := range addrs {
+		key, port := addrKeyAndPort(a)
+		xport, ok := aset[key]
+		if ok && port != xport {
+			return true
+		}
+		aset[key] = port
+	}
+
+	return false
+}
+
+func addrKeyAndPort(a ma.Multiaddr) (string, int) {
+	var (
+		key  string
+		port int
+	)
+
+	ma.ForEach(a, func(c ma.Component) bool {
+		switch c.Protocol().Code {
+		case ma.P_TCP, ma.P_UDP:
+			port = int(binary.BigEndian.Uint16(c.RawValue()))
+			key += "/" + c.Protocol().Name
+		default:
+			val := c.Value()
+			if val == "" {
+				val = c.Protocol().Name
+			}
+			key += "/" + val
+		}
+		return true
+	})
+
+	return key, port
+}
+
+// clean up addrsplosion
+// the following heuristic is used:
+// - for each base address/protocol combination, if there are multiple ports advertised then
+//   only accept the default port if present.
+//   - If the default port is not present, we check for non-standard ports by tracking
+//     private port bindings if present.
+//   - If there is no default or private port binding, then we can't infer the correct
+//     port and give up and return all addrs (for that base address)
+func sanitizeAddrsplodedSet(public, private []ma.Multiaddr) []ma.Multiaddr {
+	type portAndAddr struct {
+		addr ma.Multiaddr
+		port int
+	}
+
+	privports := make(map[int]struct{})
+	pubaddrs := make(map[string][]portAndAddr)
+
+	for _, a := range private {
+		_, port := addrKeyAndPort(a)
+		privports[port] = struct{}{}
+	}
+
+	for _, a := range public {
+		key, port := addrKeyAndPort(a)
+		pubaddrs[key] = append(pubaddrs[key], portAndAddr{addr: a, port: port})
+	}
+
+	var result []ma.Multiaddr
+	for _, pas := range pubaddrs {
+		if len(pas) == 1 {
+			// it's not addrsploded
+			result = append(result, pas[0].addr)
+			continue
+		}
+
+		haveAddr := false
+		for _, pa := range pas {
+			if _, ok := privports[pa.port]; ok {
+				// it matches a privately bound port, use it
+				result = append(result, pa.addr)
+				haveAddr = true
+				continue
+			}
+
+			if pa.port == 4001 || pa.port == 4002 {
+				// it's a default port, use it
+				result = append(result, pa.addr)
+				haveAddr = true
+			}
+		}
+
+		if !haveAddr {
+			// we weren't able to select a port; bite the bullet and use them all
+			for _, pa := range pas {
+				result = append(result, pa.addr)
+			}
+		}
+	}
+
+	return result
+}

p2p/host/relay/addrsplosion_test.go

@@ -0,0 +1,122 @@
+package relay
+
+import (
+	"testing"
+
+	ma "github.com/multiformats/go-multiaddr"
+	_ "github.com/multiformats/go-multiaddr-dns"
+)
+
+func TestCleanupAddrs(t *testing.T) {
+	// test with no addrsplosion
+	addrs := makeAddrList(
+		"/ip4/127.0.0.1/tcp/4001",
+		"/ip4/127.0.0.1/udp/4002/quic",
+		"/ip4/1.2.3.4/tcp/4001",
+		"/ip4/1.2.3.4/udp/4002/quic",
+		"/dnsaddr/somedomain.com/tcp/4002/ws",
+	)
+	clean := makeAddrList(
+		"/ip4/1.2.3.4/tcp/4001",
+		"/ip4/1.2.3.4/udp/4002/quic",
+		"/dnsaddr/somedomain.com/tcp/4002/ws",
+	)
+
+	r := cleanupAddressSet(addrs)
+	if !sameAddrs(clean, r) {
+		t.Fatal("cleaned up set doesn't match expected")
+	}
+
+	// test with default port addrspolosion
+	addrs = makeAddrList(
+		"/ip4/127.0.0.1/tcp/4001",
+		"/ip4/1.2.3.4/tcp/4001",
+		"/ip4/1.2.3.4/tcp/33333",
+		"/ip4/1.2.3.4/tcp/33334",
+		"/ip4/1.2.3.4/tcp/33335",
+		"/ip4/1.2.3.4/udp/4002/quic",
+	)
+	clean = makeAddrList(
+		"/ip4/1.2.3.4/tcp/4001",
+		"/ip4/1.2.3.4/udp/4002/quic",
+	)
+	r = cleanupAddressSet(addrs)
+	if !sameAddrs(clean, r) {
+		t.Fatal("cleaned up set doesn't match expected")
+	}
+
+	// test with default port addrsplosion but no private addrs
+	addrs = makeAddrList(
+		"/ip4/1.2.3.4/tcp/4001",
+		"/ip4/1.2.3.4/tcp/33333",
+		"/ip4/1.2.3.4/tcp/33334",
+		"/ip4/1.2.3.4/tcp/33335",
+		"/ip4/1.2.3.4/udp/4002/quic",
+	)
+	clean = makeAddrList(
+		"/ip4/1.2.3.4/tcp/4001",
+		"/ip4/1.2.3.4/udp/4002/quic",
+	)
+	r = cleanupAddressSet(addrs)
+	if !sameAddrs(clean, r) {
+		t.Fatal("cleaned up set doesn't match expected")
+	}
+
+	// test with non-standard port addrsplosion
+	addrs = makeAddrList(
+		"/ip4/127.0.0.1/tcp/12345",
+		"/ip4/1.2.3.4/tcp/12345",
+		"/ip4/1.2.3.4/tcp/33333",
+		"/ip4/1.2.3.4/tcp/33334",
+		"/ip4/1.2.3.4/tcp/33335",
+	)
+	clean = makeAddrList(
+		"/ip4/1.2.3.4/tcp/12345",
+	)
+	r = cleanupAddressSet(addrs)
+	if !sameAddrs(clean, r) {
+		t.Fatal("cleaned up set doesn't match expected")
+	}
+
+	// test with a squeaky clean address set
+	addrs = makeAddrList(
+		"/ip4/1.2.3.4/tcp/4001",
+		"/ip4/1.2.3.4/udp/4001/quic",
+	)
+	clean = addrs
+	r = cleanupAddressSet(addrs)
+	if !sameAddrs(clean, r) {
+		t.Fatal("cleaned up set doesn't match expected")
+	}
+}
+
+func makeAddrList(strs ...string) []ma.Multiaddr {
+	result := make([]ma.Multiaddr, 0, len(strs))
+	for _, s := range strs {
+		a := ma.StringCast(s)
+		result = append(result, a)
+	}
+	return result
+}
+
+func sameAddrs(as, bs []ma.Multiaddr) bool {
+	if len(as) != len(bs) {
+		return false
+	}
+
+	for _, a := range as {
+		if !findAddr(a, bs) {
+			return false
+		}
+	}
+	return true
+}
+
+func findAddr(a ma.Multiaddr, bs []ma.Multiaddr) bool {
+	for _, b := range bs {
+		if a.Equal(b) {
+			return true
+		}
+	}
+	return false
+}