PeerGroup: Add addPeersFromAddressMessage

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

@@ -148,6 +148,10 @@ public class PeerGroup implements TransactionBroadcaster {
     // How many connections we want to have open at the current time. If we lose connections, we'll try opening more
     // until we reach this count.
     @GuardedBy("lock") private int maxConnections;
+    // if true, we will listen to "addr" network messages and add nodes discovered this way.
+    // if false, only nodes found by discovery process are used/added.
+    @GuardedBy("lock")
+    private boolean addPeersFromAddressMessage = true;
     // Minimum protocol version we will allow ourselves to connect to: require Bloom filtering.
     private volatile int vMinRequiredProtocolVersion;
 
@@ -250,7 +254,7 @@ public void onBlocksDownloaded(Peer peer, Block block, @Nullable FilteredBlock f
         }
     }
 
-    private class PeerStartupListener implements PeerConnectedEventListener, PeerDisconnectedEventListener {
+    private class PeerStartupListener implements PeerConnectedEventListener, PeerDisconnectedEventListener, PreMessageReceivedEventListener {
         @Override
         public void onPeerConnected(Peer peer, int peerCount) {
             handleNewPeer(peer);
@@ -261,6 +265,18 @@ public void onPeerDisconnected(Peer peer, int peerCount) {
             // The channel will be automatically removed from channels.
             handlePeerDeath(peer, null);
         }
+
+        @Override
+        public Message onPreMessageReceived(Peer peer, Message m) {
+            if (m instanceof AddressMessage && addPeersFromAddressMessage) {
+                for( PeerAddress peerAddress : ((AddressMessage)m).getAddresses() ) {
+                    addInactive(peerAddress);
+                }
+            }
+
+            // Just pass the message right through for further processing.
+            return m;
+        }
     }
 
     private final PeerStartupListener startupListener = new PeerStartupListener();
@@ -487,6 +503,20 @@ public void setMaxConnections(int maxConnections) {
             channels.closeConnections(-adjustment);
     }
 
+    /**
+     * Switch for enabling network peer discovery.
+     *   if true, we will listen to "addr" network messages and add nodes discovered this way.
+     *   if false, only nodes found by discovery process are used/added.
+     */
+    public void setAddPeersFromAddressMessage(boolean addPeersFromAddressMessage) {
+        lock.lock();
+        try {
+            this.addPeersFromAddressMessage = addPeersFromAddressMessage;
+        } finally {
+            lock.unlock();
+        }
+    }
+
     /**
      * Configure download of pending transaction dependencies. A change of values only takes effect for newly connected
      * peers.
@@ -1130,6 +1160,10 @@ private boolean maybeCheckForLocalhostPeer() {
                 socket = new Socket();
                 socket.connect(new InetSocketAddress(InetAddresses.forString("127.0.0.1"), params.getPort()), vConnectTimeoutMillis);
                 localhostCheckState = LocalhostCheckState.FOUND;
+
+                // If we are connected to localhost we don't want to get other peers added from AddressMessage calls.
+                setAddPeersFromAddressMessage(false);
+
                 return true;
             } catch (IOException e) {
                 log.info("Localhost peer not detected.");