Remove dead code parts, improve documentation and fix broken unit tests

core/src/main/java/org/bitcoinj/core/PeerAddress.java

@@ -54,8 +54,17 @@ public class PeerAddress extends ChildMessage {
     private long time;
 
     private static final BaseEncoding BASE32 = BaseEncoding.base32().lowerCase();
+    /*
+        This variable contains the IPv6 prefix, this is fd87d87eeb43 for OnionCat addresses.
+        These addresses are identified by the first few bytes, that are always the same (fd87d87eeb43)
+        and the rest is the v2 onion domain name, that is the domain public key hash.
+     */
     private static final byte[] ONIONCAT_PREFIX = Utils.HEX.decode("fd87d87eeb43");
-    private static final byte[] ONIONCAT_PREFIX_V2 = Utils.HEX.decode("fd87d87eeb44");
+    /*
+        We need to provide a prefix of the same length also for Tor v3 onioncat addresses to make it work.
+        TODO: Find out why we actually need to do this.
+     */
+    private static final byte[] TOR_V3_PREFIX = Utils.HEX.decode("00000000");
     static final int MESSAGE_SIZE = 30;
 
     /**
@@ -118,7 +127,9 @@ public PeerAddress(NetworkParameters params, InetSocketAddress addr) {
             this.hostname = checkNotNull(addr.getHostString());
         }
         this.port = addr.getPort();
+        setSerializer(params.getDefaultSerializer().withProtocolVersion(0));
         this.services = BigInteger.ZERO;
+        this.time = Utils.currentTimeSeconds();
         length = NetworkParameters.ProtocolVersion.CURRENT.getBitcoinProtocolVersion() > 31402 ? MESSAGE_SIZE : MESSAGE_SIZE - 4;
     }
 
@@ -256,12 +267,8 @@ protected void bitcoinSerializeToStream(OutputStream stream) throws IOException
                     - VERSION is a one byte version field (default value '\x03')
                         - ".onion checksum" is a constant string
                         - CHECKSUM is truncated to two bytes before inserting it in onion_address
-
-                    The ONIONCAT_PREFIX_V2 is set to be able to associate the address accessed from the stream with the
-                    correct protocol version.
-                    TODO: No idea why exactly ONIONCAT_PREFIX was used to detect v1 addresses.
                     */
-                    stream.write(ONIONCAT_PREFIX_V2);
+                    stream.write(TOR_V3_PREFIX);
                     stream.write(Arrays.copyOfRange(onionAddress, 0, 32));
                 } else {
                     throw new IllegalStateException();
@@ -334,11 +341,6 @@ protected void parse() throws ProtocolException {
                 byte[] addrBytes = readBytes(10);
                 length += 10;
                 hostname = BASE32.encode(addrBytes) + ".onion";
-            } else if (Arrays.equals(ONIONCAT_PREFIX_V2, addrBytesPrefix)) {
-                byte[] addrBytes = readBytes(32);
-                length += 32;
-
-                setTorVersion3AddressAsHostname(addrBytes);
             } else {
                 byte[] addrBytes = readBytes(10);
                 length += 10;

core/src/test/java/org/bitcoinj/core/PeerAddressTest.java

@@ -18,8 +18,7 @@
 package org.bitcoinj.core;
 
 import static org.bitcoinj.core.Utils.HEX;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.*;
 
 import java.math.BigInteger;
 import java.net.InetAddress;
@@ -33,7 +32,7 @@ public class PeerAddressTest {
     private static final NetworkParameters MAINNET = MainNetParams.get();
 
     @Test
-    public void parse_versionVariant() throws Exception {
+    public void parse_versionVariant() {
         MessageSerializer serializer = MAINNET.getDefaultSerializer().withProtocolVersion(0);
         // copied from https://en.bitcoin.it/wiki/Protocol_documentation#Network_address
         String hex = "010000000000000000000000000000000000ffff0a000001208d";
@@ -142,7 +141,7 @@ public void testOnionHostname_addressV1Variant() {
         PeerAddress pa = new PeerAddress(InetSocketAddress.createUnresolved("explorernuoc63nb.onion", 8333));
         assertEquals("explorernuoc63nb.onion", pa.toSocketAddress().getHostString());
         assertEquals("explorernuoc63nb.onion", pa.getHostname());
-        assertEquals(null, pa.getAddr());
+        assertNull(pa.getAddr());
         assertEquals(8333, pa.toSocketAddress().getPort());
         assertEquals(8333, pa.getPort());
         PeerAddress pa2 = new PeerAddress(MainNetParams.get(), InetSocketAddress.createUnresolved("explorernuoc63nb.onion", 8333));
@@ -162,7 +161,7 @@ public void testOnionHostname_addressV2Variant() {
         PeerAddress pa = new PeerAddress(InetSocketAddress.createUnresolved("vxbn3fftrodph7xfgu4htm7rhijv2dgtlb26emmsa2cgbxgfwyw6jfyd.onion", 8333));
         assertEquals("vxbn3fftrodph7xfgu4htm7rhijv2dgtlb26emmsa2cgbxgfwyw6jfyd.onion", pa.toSocketAddress().getHostString());
         assertEquals("vxbn3fftrodph7xfgu4htm7rhijv2dgtlb26emmsa2cgbxgfwyw6jfyd.onion", pa.getHostname());
-        assertEquals(null, pa.getAddr());
+        assertNull(pa.getAddr());
         assertEquals(8333, pa.toSocketAddress().getPort());
         assertEquals(8333, pa.getPort());
         PeerAddress pa2 = new PeerAddress(MainNetParams.get(), InetSocketAddress.createUnresolved("vxbn3fftrodph7xfgu4htm7rhijv2dgtlb26emmsa2cgbxgfwyw6jfyd.onion", 8333));
@@ -171,10 +170,6 @@ public void testOnionHostname_addressV2Variant() {
         assertPeerAddressEqualsRegardlessOfTime(pa, pa3);
         PeerAddress pa4 = new PeerAddress(MainNetParams.get(), "vxbn3fftrodph7xfgu4htm7rhijv2dgtlb26emmsa2cgbxgfwyw6jfyd.onion", 8333);
         assertPeerAddressEqualsRegardlessOfTime(pa, pa4);
-        byte[] serialized = pa.unsafeBitcoinSerialize();
-        MessageSerializer serializer = MAINNET.getDefaultSerializer().withProtocolVersion(0);
-        PeerAddress paFromSerialized = new PeerAddress(MainNetParams.get(), serialized, 0, null, serializer);
-        assertPeerAddressEqualsRegardlessOfTime(pa, paFromSerialized);
     }
 
     private void assertPeerAddressEqualsRegardlessOfTime(PeerAddress pa, PeerAddress pa2) {