From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Mon, 15 Jul 2019 08:28:01 +0000 (+0200)
Subject: dnsdist: Catch exceptions thrown when handling a TCP response
X-Git-Tag: dnsdist-1.4.0-rc1~47^2~1
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0ffc95ec7b1b85d766f617e095e1a69096a5a2b4;p=pdns

dnsdist: Catch exceptions thrown when handling a TCP response

We need to handle it gracefully if a function called from
handleResponse() throws, most likely because the answer received
from the backend was not valid.
---

diff --git a/pdns/dnsdist-tcp.cc b/pdns/dnsdist-tcp.cc
index be50cd305..e49897902 100644
--- a/pdns/dnsdist-tcp.cc
+++ b/pdns/dnsdist-tcp.cc
@@ -968,7 +968,12 @@ static void handleDownstreamIO(std::shared_ptr<IncomingTCPConnectionState>& stat
         fd = -1;
 
         state->d_responseReadTime = now;
-        handleResponse(state, now);
+        try {
+          handleResponse(state, now);
+        }
+        catch (const std::exception& e) {
+          vinfolog("Got an exception while handling TCP response from %s (client is %s): %s", state->d_ds ? state->d_ds->getName() : "unknown", state->d_ci.remote.toStringWithPort(), e.what());
+        }
         return;
       }
     }
@@ -993,7 +998,7 @@ static void handleDownstreamIO(std::shared_ptr<IncomingTCPConnectionState>& stat
     }
 
     /* don't increase this counter when reusing connections */
-    if (state->d_downstreamConnection->isFresh()) {
+    if (state->d_downstreamConnection && state->d_downstreamConnection->isFresh()) {
       ++state->d_downstreamFailures;
     }
     if (state->d_outstanding && state->d_ds != nullptr) {