From e724d52a22f8513f1fe6004489ffd84c3c22e013 Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Mon, 22 Jul 2019 10:36:57 +0200
Subject: [PATCH] dnsdist: Double-check we only increment the outstanding
 counter once

---
 pdns/dnsdist-tcp.cc | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/pdns/dnsdist-tcp.cc b/pdns/dnsdist-tcp.cc
index bc87e06a0..b250004d3 100644
--- a/pdns/dnsdist-tcp.cc
+++ b/pdns/dnsdist-tcp.cc
@@ -704,7 +704,7 @@ static void sendResponse(std::shared_ptr<IncomingTCPConnectionState>& state, str
 
 static void handleResponse(std::shared_ptr<IncomingTCPConnectionState>& state, struct timeval& now)
 {
-  if (state->d_responseSize < sizeof(dnsheader)) {
+  if (state->d_responseSize < sizeof(dnsheader) || !state->d_ds) {
     return;
   }
 
@@ -936,7 +936,7 @@ static void handleDownstreamIO(std::shared_ptr<IncomingTCPConnectionState>& stat
         state->d_currentPos = 0;
         state->d_querySentTime = now;
         iostate = IOState::NeedRead;
-        if (!state->d_isXFR) {
+        if (!state->d_isXFR && !state->d_outstanding) {
           /* don't bother with the outstanding count for XFR queries */
           ++state->d_ds->outstanding;
           state->d_outstanding = true;
@@ -1012,9 +1012,13 @@ static void handleDownstreamIO(std::shared_ptr<IncomingTCPConnectionState>& stat
     if (state->d_downstreamConnection && state->d_downstreamConnection->isFresh()) {
       ++state->d_downstreamFailures;
     }
-    if (state->d_outstanding && state->d_ds != nullptr) {
-      --state->d_ds->outstanding;
+
+    if (state->d_outstanding) {
       state->d_outstanding = false;
+
+      if (state->d_ds != nullptr) {
+        --state->d_ds->outstanding;
+      }
     }
     /* remove this FD from the IO multiplexer */
     iostate = IOState::Done;
-- 
2.40.0