From f9c57c98da1b1007a51680629b667d57d9b702b8 Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Tue, 5 Dec 2017 17:07:19 +0100
Subject: [PATCH] dnsreplay: Bail out on a too small outgoing buffer

---
 pdns/dnsreplay.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pdns/dnsreplay.cc b/pdns/dnsreplay.cc
index 4c5f218c9..a671472f6 100644
--- a/pdns/dnsreplay.cc
+++ b/pdns/dnsreplay.cc
@@ -595,7 +595,7 @@ static void addECSOption(char* packet, const size_t& packetSize, uint16_t* len,
 
   uint16_t arcount = ntohs(dh->arcount);
   /* does it fit in the existing buffer? */
-  if (packetSize - *len > EDNSRR.size()) {
+  if (packetSize > *len && packetSize - *len > EDNSRR.size()) {
     arcount++;
     dh->arcount = htons(arcount);
     memcpy(packet + *len, EDNSRR.c_str(), EDNSRR.size());
-- 
2.49.0