From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Fri, 29 Mar 2024 14:08:29 +0000 (+0100)
Subject: dnsdist: Release failed TCP backend connections more quickly
X-Git-Tag: rec-5.1.0-alpha1~72^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F14004%2Fhead;p=thirdparty%2Fpdns.git

dnsdist: Release failed TCP backend connections more quickly

After a timeout we cannot reuse the TCP connection to the backend
anyway, so let's release it immediately.
---

diff --git a/pdns/dnsdistdist/dnsdist-tcp-downstream.cc b/pdns/dnsdistdist/dnsdist-tcp-downstream.cc
index 684c46fcee..e72d9ac180 100644
--- a/pdns/dnsdistdist/dnsdist-tcp-downstream.cc
+++ b/pdns/dnsdistdist/dnsdist-tcp-downstream.cc
@@ -146,6 +146,13 @@ void TCPConnectionToBackend::release(){
   if (d_ioState) {
     d_ioState.reset();
   }
+
+  auto shared = std::dynamic_pointer_cast<TCPConnectionToBackend>(shared_from_this());
+  if (!willBeReusable(true)) {
+    /* remove ourselves from the connection cache, this might mean that our
+       reference count drops to zero after that, so we need to be careful */
+    t_downstreamTCPConnectionsManager.removeDownstreamConnection(shared);
+  }
 }
 
 static uint32_t getSerialFromRawSOAContent(const std::vector<uint8_t>& raw)
diff --git a/pdns/dnsdistdist/test-dnsdisttcp_cc.cc b/pdns/dnsdistdist/test-dnsdisttcp_cc.cc
index 3566d61c50..a27029361b 100644
--- a/pdns/dnsdistdist/test-dnsdisttcp_cc.cc
+++ b/pdns/dnsdistdist/test-dnsdisttcp_cc.cc
@@ -3620,8 +3620,8 @@ BOOST_FIXTURE_TEST_CASE(test_IncomingConnectionOOOR_BackendOOOR, TestFixture)
     g_tcpRecvTimeout = 2;
 
     /* we need to clear them now, otherwise we end up with dangling pointers to the steps via the TLS context, etc */
-    /* we have one connection to clear, no proxy protocol */
-    BOOST_CHECK_EQUAL(IncomingTCPConnectionState::clearAllDownstreamConnections(), 1U);
+    /* we have no connection to clear, because there was a timeout! */
+    BOOST_CHECK_EQUAL(IncomingTCPConnectionState::clearAllDownstreamConnections(), 0U);
   }
 
   {