From 67e1434b51c6fcafe61de6dc6cb08d84ad1877f5 Mon Sep 17 00:00:00 2001
From: Andreas Schildbach <andreas@schildbach.de>
Date: Fri, 26 Feb 2016 20:49:09 +0100
Subject: [PATCH] Peer: Receiving main protocol messages before version
 handshake completed is a protocol violation.

---
 core/src/main/java/org/bitcoinj/core/Peer.java | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/core/src/main/java/org/bitcoinj/core/Peer.java b/core/src/main/java/org/bitcoinj/core/Peer.java
index 361ef627c..a512d8531 100644
--- a/core/src/main/java/org/bitcoinj/core/Peer.java
+++ b/core/src/main/java/org/bitcoinj/core/Peer.java
@@ -459,6 +459,12 @@ public class Peer extends PeerSocketHandler {
             currentFilteredBlock = null;
         }
 
+        // No further communication is possible until version handshake is complete.
+        if (!(m instanceof VersionMessage || m instanceof VersionAck
+                || (versionHandshakeFuture.isDone() && !versionHandshakeFuture.isCancelled())))
+            throw new ProtocolException(
+                    "Received " + m.getClass().getSimpleName() + " before version handshake is complete.");
+
         if (m instanceof Ping) {
             processPing((Ping) m);
         } else if (m instanceof Pong) {