From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Thu, 24 May 2018 15:35:39 +0000 (+0200)
Subject: dnsdist: Don't reconnect the socket on healthcheck failure
X-Git-Tag: dnsdist-1.3.1~56^2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1b12622540e11f6f8547f5af5cc5db67890cad2e;p=pdns

dnsdist: Don't reconnect the socket on healthcheck failure
---

diff --git a/pdns/dnsdist.cc b/pdns/dnsdist.cc
index aeec6f39b..73b013655 100644
--- a/pdns/dnsdist.cc
+++ b/pdns/dnsdist.cc
@@ -1077,7 +1077,7 @@ bool processResponse(LocalStateHolder<vector<DNSDistResponseRuleAction> >& local
   return true;
 }
 
-static ssize_t udpClientSendRequestToBackend(DownstreamState* ss, const int sd, const char* request, const size_t requestLen)
+static ssize_t udpClientSendRequestToBackend(DownstreamState* ss, const int sd, const char* request, const size_t requestLen, bool healthCheck=false)
 {
   ssize_t result;
 
@@ -1098,8 +1098,11 @@ static ssize_t udpClientSendRequestToBackend(DownstreamState* ss, const int sd,
     vinfolog("Error sending request to backend %s: %d", ss->remote.toStringWithPort(), savederrno);
 
     /* This might sound silly, but on Linux send() might fail with EINVAL
-       if the interface the socket was bound to doesn't exist anymore. */
-    if (savederrno == EINVAL) {
+       if the interface the socket was bound to doesn't exist anymore.
+       We don't want to reconnect the real socket if the healthcheck failed,
+       because it's not using the same socket.
+    */
+    if (!healthCheck && (savederrno == EINVAL || savederrno == ENODEV)) {
       ss->reconnect();
     }
   }
@@ -1679,7 +1682,7 @@ try
     sock.bind(ds.sourceAddr);
   }
   sock.connect(ds.remote);
-  ssize_t sent = udpClientSendRequestToBackend(&ds, sock.getHandle(), (char*)&packet[0], packet.size());
+  ssize_t sent = udpClientSendRequestToBackend(&ds, sock.getHandle(), (char*)&packet[0], packet.size(), true);
   if (sent < 0) {
     int ret = errno;
     if (g_verboseHealthChecks)