From 709e6f75624d80cb23abac2fc0bedebdde525cc6 Mon Sep 17 00:00:00 2001
From: Andreas Schildbach <andreas@schildbach.de>
Date: Fri, 26 Feb 2016 19:06:22 +0100
Subject: [PATCH] Peer: Both halves of the version handshake need to be
 complete before the protocol can continue.

---
 .../src/main/java/org/bitcoinj/core/Peer.java | 36 +++++++++++++------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/core/src/main/java/org/bitcoinj/core/Peer.java b/core/src/main/java/org/bitcoinj/core/Peer.java
index 22fd22c3..361ef627 100644
--- a/core/src/main/java/org/bitcoinj/core/Peer.java
+++ b/core/src/main/java/org/bitcoinj/core/Peer.java
@@ -153,11 +153,13 @@ public class Peer extends PeerSocketHandler {
     private static final int PING_MOVING_AVERAGE_WINDOW = 20;
 
     private volatile VersionMessage vPeerVersionMessage;
-    private boolean isAcked;
 
     // A settable future which completes (with this) when the connection is open
     private final SettableFuture<Peer> connectionOpenFuture = SettableFuture.create();
-    private final SettableFuture<Peer> versionHandshakeFuture = SettableFuture.create();
+    private final SettableFuture<Peer> outgoingVersionHandshakeFuture = SettableFuture.create();
+    private final SettableFuture<Peer> incomingVersionHandshakeFuture = SettableFuture.create();
+    private final ListenableFuture<List<Peer>> versionHandshakeFuture = Futures
+            .allAsList(outgoingVersionHandshakeFuture, incomingVersionHandshakeFuture);
 
     /**
      * <p>Construct a peer that reads/writes from the given block chain.</p>
@@ -219,11 +221,17 @@ public class Peer extends PeerSocketHandler {
         this.getDataFutures = new CopyOnWriteArrayList<GetDataRequest>();
         this.getAddrFutures = new LinkedList<SettableFuture<AddressMessage>>();
         this.fastCatchupTimeSecs = params.getGenesisBlock().getTimeSeconds();
-        this.isAcked = false;
         this.pendingPings = new CopyOnWriteArrayList<PendingPing>();
         this.vMinProtocolVersion = params.getProtocolVersionNum(NetworkParameters.ProtocolVersion.PONG);
         this.wallets = new CopyOnWriteArrayList<Wallet>();
         this.context = Context.get();
+
+        this.versionHandshakeFuture.addListener(new Runnable() {
+            @Override
+            public void run() {
+                versionHandshakeComplete();
+            }
+        }, Threading.SAME_THREAD);
     }
 
     /**
@@ -426,7 +434,7 @@ public class Peer extends PeerSocketHandler {
         return connectionOpenFuture;
     }
 
-    public ListenableFuture<Peer> getVersionHandshakeFuture() {
+    public ListenableFuture<List<Peer>> getVersionHandshakeFuture() {
         return versionHandshakeFuture;
     }
 
@@ -527,9 +535,6 @@ public class Peer extends PeerSocketHandler {
                 vPeerVersionMessage.localServices,
                 String.format(Locale.US, "%tF %tT", peerTime, peerTime),
                 vPeerVersionMessage.bestHeight);
-        // Now it's our turn ...
-        // Send an ACK message stating we accept the peers protocol version.
-        sendMessage(new VersionAck());
         // bitcoinj is a client mode implementation. That means there's not much point in us talking to other client
         // mode nodes because we can't download the data from them we need to find/verify transactions. Some bogus
         // implementations claim to have a block chain in their services field but then report a height of zero, filter
@@ -544,18 +549,27 @@ public class Peer extends PeerSocketHandler {
         if (vPeerVersionMessage.bestHeight < 0)
             // In this case, it's a protocol violation.
             throw new ProtocolException("Peer reports invalid best height: " + vPeerVersionMessage.bestHeight);
-        versionHandshakeFuture.set(this);
+        // Now it's our turn ...
+        // Send an ACK message stating we accept the peers protocol version.
+        sendMessage(new VersionAck());
+        log.debug("{}: Incoming version handshake complete.", this);
+        incomingVersionHandshakeFuture.set(this);
     }
 
     private void processVersionAck(VersionAck m) throws ProtocolException {
         if (vPeerVersionMessage == null) {
             throw new ProtocolException("got a version ack before version");
         }
-        if (isAcked) {
+        if (outgoingVersionHandshakeFuture.isDone()) {
             throw new ProtocolException("got more than one version ack");
         }
-        isAcked = true;
-        this.setTimeoutEnabled(false);
+        log.debug("{}: Outgoing version handshake complete.", this);
+        outgoingVersionHandshakeFuture.set(this);
+    }
+
+    private void versionHandshakeComplete() {
+        log.debug("{}: Handshake complete.", this);
+        setTimeoutEnabled(false);
         for (final ListenerRegistration<PeerConnectedEventListener> registration : connectedEventListeners) {
             registration.executor.execute(new Runnable() {
                 @Override