multi: remove tor v2 onion address encoder paths

Drop the v2 onion encoder branches from lnwire.WriteOnionAddr,
graph/db.encodeOnionAddr, graph/db.collectAddressRecords, and the
tor.OnionHostToFakeIP helper. lnd no longer produces v2 onion addresses
on any code path.

Decoders for v2 addresses are intentionally retained in lnwire,
graph/db, and tor so that existing graph databases and peer-announced
v2 addresses continue to deserialize. Update unit tests to use v3 onion
fixtures.

Author: erickcestari

chanbackup/single_test.go

@@ -38,8 +38,9 @@ var (
 	addr1, _ = net.ResolveTCPAddr("tcp", "10.0.0.2:9000")
 	addr2, _ = net.ResolveTCPAddr("tcp", "10.0.0.3:9000")
 	addr3    = &tor.OnionAddr{
-		OnionService: "3g2upl4pq6kufc4m.onion",
-		Port:         9735,
+		OnionService: "vww6ybal4bd7szmgncyruucpgfkqahzd" +
+			"di37ktceo3ah7ngmcopnpyyd.onion",
+		Port: 9735,
 	}
 	addr4 = &lnwire.DNSAddress{
 		Hostname: "example.com",

channeldb/codec.go

@@ -189,16 +189,24 @@ func WriteElement(w io.Writer, element interface{}) error {
 		}
 
 	case net.Addr:
-		if err := graphdb.SerializeAddr(w, e); err != nil {
+		// Route through the filter so a stale v2 onion address is
+		// dropped (with a warning) rather than failing the whole
+		// write with "unknown onion service length".
+		filtered := graphdb.FilterSerializableAddrs([]net.Addr{e})
+		if len(filtered) == 0 {
+			return nil
+		}
+		if err := graphdb.SerializeAddr(w, filtered[0]); err != nil {
 			return err
 		}
 
 	case []net.Addr:
-		if err := WriteElement(w, uint32(len(e))); err != nil {
+		addrs := graphdb.FilterSerializableAddrs(e)
+		if err := WriteElement(w, uint32(len(addrs))); err != nil {
 			return err
 		}
 
-		for _, addr := range e {
+		for _, addr := range addrs {
 			if err := graphdb.SerializeAddr(w, addr); err != nil {
 				return err
 			}

channeldb/nodes.go

@@ -358,13 +358,14 @@ func serializeLinkNode(w io.Writer, l *LinkNode) error {
 		return err
 	}
 
-	numAddrs := uint32(len(l.Addresses))
+	addresses := graphdb.FilterSerializableAddrs(l.Addresses)
+	numAddrs := uint32(len(addresses))
 	byteOrder.PutUint32(buf[:4], numAddrs)
 	if _, err := w.Write(buf[:4]); err != nil {
 		return err
 	}
 
-	for _, addr := range l.Addresses {
+	for _, addr := range addresses {
 		if err := graphdb.SerializeAddr(w, addr); err != nil {
 			return err
 		}

docs/configuring_tor.md

@@ -15,13 +15,13 @@ by using Tor for anonymous networking to establish connections.
 
 With widespread usage of Onion Services within the network, concerns about the
 difficulty of proper NAT traversal are alleviated, as usage of onion services
-allows nodes to accept inbound connections even if they're behind a NAT. At the
-time of writing this documentation, `lnd` supports both types of onion services:
-v2 and v3.
+allows nodes to accept inbound connections even if they're behind a NAT. `lnd`
+supports v3 onion services only; legacy v2 onion service support has been
+removed.
 
-Before following the remainder of this documentation, you should ensure that you
-already have Tor installed locally. **If you want to run v3 Onion Services, make
-sure that you run at least version 0.3.3.6.**
+Before following the remainder of this documentation, you should ensure that
+you already have Tor installed locally. **Make sure that you run at least
+version 0.3.3.6 of Tor in order to use v3 Onion Services.**
 Official instructions to install the latest release of Tor can be found
 [here](https://www.torproject.org/docs/tor-doc-unix.html.en).
 

graph/db/addr.go

@@ -104,11 +104,6 @@ func encodeOnionAddr(w io.Writer, addr *tor.OnionAddr) error {
 	var suffixIndex int
 	hostLen := len(addr.OnionService)
 	switch hostLen {
-	case tor.V2Len:
-		if _, err := w.Write([]byte{byte(v2OnionAddr)}); err != nil {
-			return err
-		}
-		suffixIndex = tor.V2Len - tor.OnionSuffixLen
 	case tor.V3Len:
 		if _, err := w.Write([]byte{byte(v3OnionAddr)}); err != nil {
 			return err
@@ -131,12 +126,7 @@ func encodeOnionAddr(w io.Writer, addr *tor.OnionAddr) error {
 	}
 
 	// Sanity check the decoded length.
-	switch {
-	case hostLen == tor.V2Len && len(host) != tor.V2DecodedLen:
-		return fmt.Errorf("onion service %v decoded to invalid host %x",
-			addr.OnionService, host)
-
-	case hostLen == tor.V3Len && len(host) != tor.V3DecodedLen:
+	if hostLen == tor.V3Len && len(host) != tor.V3DecodedLen {
 		return fmt.Errorf("onion service %v decoded to invalid host %x",
 			addr.OnionService, host)
 	}
@@ -322,3 +312,26 @@ func SerializeAddr(w io.Writer, address net.Addr) error {
 		return ErrUnknownAddressType
 	}
 }
+
+// FilterSerializableAddrs returns the subset of addresses that this package
+// can currently serialize. Legacy Tor v2 onion addresses are dropped (with a
+// warning) since lnd no longer persists them; pre-existing v2 addresses on
+// disk can still be deserialized, but any rewrite path must call this helper
+// before counting and encoding the address slice so that node updates do not
+// fail when a stale v2 address is present.
+func FilterSerializableAddrs(addrs []net.Addr) []net.Addr {
+	out := make([]net.Addr, 0, len(addrs))
+	for _, a := range addrs {
+		onion, ok := a.(*tor.OnionAddr)
+		if ok && len(onion.OnionService) == tor.V2Len {
+			log.Warnf("Dropping legacy v2 onion address %v "+
+				"during serialization; v2 is no longer "+
+				"supported", onion)
+
+			continue
+		}
+		out = append(out, a)
+	}
+
+	return out
+}

graph/db/addr_test.go

@@ -29,11 +29,6 @@ var (
 		Port: 65535,
 	}
 
-	testOnionV2Addr = &tor.OnionAddr{
-		OnionService: "3g2upl4pq6kufc4m.onion",
-		Port:         9735,
-	}
-
 	testOnionV3Addr = &tor.OnionAddr{
 		OnionService: "vww6ybal4bd7szmgncyruucpgfkqahzddi37ktceo3ah7ngmcopnpyyd.onion", //nolint:ll
 		Port:         80,
@@ -63,9 +58,6 @@ var addrTests = []struct {
 	{
 		expAddr: testIPV6Addr,
 	},
-	{
-		expAddr: testOnionV2Addr,
-	},
 	{
 		expAddr: testOnionV3Addr,
 	},

graph/db/graph_test.go

@@ -400,8 +400,7 @@ func testNodeInsertionAndDeletion(t *testing.T, v lnwire.GossipVersion) {
 		// Add 2 IPV6 addresses.
 		testIPV6Addr,
 		anotherAddr,
-		// Add one v2 and one v3 onion address.
-		testOnionV2Addr,
+		// Add a v3 onion address.
 		testOnionV3Addr,
 		// Add a DNS host address.
 		testDNSAddr,
@@ -439,7 +438,6 @@ func testNodeInsertionAndDeletion(t *testing.T, v lnwire.GossipVersion) {
 
 	// Finally, update the set to only contain the Tor addresses.
 	expAddrs = []net.Addr{
-		testOnionV2Addr,
 		testOnionV3Addr,
 	}
 	node = nodeWithAddrs(expAddrs)

graph/db/kv_store.go

@@ -4699,13 +4699,14 @@ func putLightningNode(nodeBucket, aliasBucket, updateIndex kvdb.RwBucket,
 		return err
 	}
 
-	numAddresses := uint16(len(node.Addresses))
+	addresses := FilterSerializableAddrs(node.Addresses)
+	numAddresses := uint16(len(addresses))
 	byteOrder.PutUint16(scratch[:2], numAddresses)
 	if _, err := b.Write(scratch[:2]); err != nil {
 		return err
 	}
 
-	for _, address := range node.Addresses {
+	for _, address := range addresses {
 		if err := SerializeAddr(&b, address); err != nil {
 			return err
 		}

graph/db/sql_store.go

@@ -4821,7 +4821,6 @@ func collectAddressRecords(addresses []net.Addr) (map[dbAddressType][]string,
 	newAddresses := map[dbAddressType][]string{
 		addressTypeIPv4:   {},
 		addressTypeIPv6:   {},
-		addressTypeTorV2:  {},
 		addressTypeTorV3:  {},
 		addressTypeDNS:    {},
 		addressTypeOpaque: {},
@@ -4844,10 +4843,12 @@ func collectAddressRecords(addresses []net.Addr) (map[dbAddressType][]string,
 
 		case *tor.OnionAddr:
 			switch len(addr.OnionService) {
-			case tor.V2Len:
-				addAddr(addressTypeTorV2, addr)
 			case tor.V3Len:
 				addAddr(addressTypeTorV3, addr)
+			case tor.V2Len:
+				log.Warnf("Dropping legacy v2 onion address "+
+					"%v during upsert; v2 is no longer "+
+					"supported", addr)
 			default:
 				return nil, fmt.Errorf("invalid length for " +
 					"a tor address")

itest/lnd_channel_graph_test.go

@@ -378,7 +378,6 @@ func testNodeAnnouncement(ht *lntest.HarnessTest) {
 	advertisedAddrs := []string{
 		"192.168.1.1:8333",
 		"[2001:db8:85a3:8d3:1319:8a2e:370:7348]:8337",
-		"bkb6azqggsaiskzi.onion:9735",
 		"fomvuglh6h6vcag73xo5t5gv56ombih3zr2xvplkpbfd7wrog4swj" +
 			"wid.onion:1234",
 	}
@@ -435,7 +434,6 @@ func testUpdateNodeAnnouncement(ht *lntest.HarnessTest) {
 	extraAddrs := []string{
 		"192.168.1.1:8333",
 		"[2001:db8:85a3:8d3:1319:8a2e:370:7348]:8337",
-		"bkb6azqggsaiskzi.onion:9735",
 		"fomvuglh6h6vcag73xo5t5gv56ombih3zr2xvplkpbfd7wrog4swj" +
 			"wid.onion:1234",
 	}