From ba04c4a7801e7d68a5e84035b919e5c3626eb7a7 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Thu, 5 Mar 2015 04:01:22 -0800
Subject: [PATCH] Limit message sizes before transfer

This introduces a fixed limit for the size of p2p messages, and enforces it
before download.
---
 src/net.cpp | 5 +++++
 src/net.h   | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/src/net.cpp b/src/net.cpp
index 3c3666615..d9f470b9e 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -523,6 +523,11 @@ bool CNode::ReceiveMsgBytes(const char *pch, unsigned int nBytes)
         if (handled < 0)
                 return false;
 
+        if (msg.in_data && msg.hdr.nMessageSize > MAX_PROTOCOL_MESSAGE_LENGTH) {
+            LogPrint("net", "Oversized message from peer=%i, disconnecting", GetId());
+            return false;
+        }
+
         pch += handled;
         nBytes -= handled;
 
diff --git a/src/net.h b/src/net.h
index d2b2d88dd..24275d4a9 100644
--- a/src/net.h
+++ b/src/net.h
@@ -46,6 +46,8 @@ static const int TIMEOUT_INTERVAL = 20 * 60;
 static const unsigned int MAX_INV_SZ = 50000;
 /** The maximum number of new addresses to accumulate before announcing. */
 static const unsigned int MAX_ADDR_TO_SEND = 1000;
+/** Maximum length of incoming protocol messages (no message over 2 MiB is currently acceptable). */
+static const unsigned int MAX_PROTOCOL_MESSAGE_LENGTH = 2 * 1024 * 1024;
 /** -listen default */
 static const bool DEFAULT_LISTEN = true;
 /** -upnp default */