From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Wed, 3 Aug 2016 09:07:10 +0000 (+0200)
Subject: dnsdist: Add unreachable servers, connect when they are up
X-Git-Tag: rec-4.1.0-alpha1~334^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7565f4e613a68ab25085203ac0daae1676b1efdc;p=thirdparty%2Fpdns.git

dnsdist: Add unreachable servers, connect when they are up
---

diff --git a/pdns/dnsdist-lua.cc b/pdns/dnsdist-lua.cc
index 8e122046cf..53e5b43e25 100644
--- a/pdns/dnsdist-lua.cc
+++ b/pdns/dnsdist-lua.cc
@@ -226,13 +226,15 @@ vector<std::function<void(void)>> setupLua(bool client, const std::string& confi
 			  addServerToPool(localPools, "", ret);
 			  g_pools.setState(localPools);
 
-			  if(g_launchWork) {
-			    g_launchWork->push_back([ret]() {
-				ret->tid = move(thread(responderThread, ret));
+			  if (ret->connected) {
+			    if(g_launchWork) {
+			      g_launchWork->push_back([ret]() {
+			        ret->tid = move(thread(responderThread, ret));
 			      });
-			  }
-			  else {
-			    ret->tid = move(thread(responderThread, ret));
+			    }
+			    else {
+			      ret->tid = move(thread(responderThread, ret));
+			    }
 			  }
 
 			  return ret;
@@ -372,13 +374,15 @@ vector<std::function<void(void)>> setupLua(bool client, const std::string& confi
 			  ret->maxCheckFailures=std::stoi(boost::get<string>(vars["maxCheckFailures"]));
 			}
 
-			if(g_launchWork) {
-			  g_launchWork->push_back([ret]() {
+			if (ret->connected) {
+			  if(g_launchWork) {
+			    g_launchWork->push_back([ret]() {
 			      ret->tid = move(thread(responderThread, ret));
 			    });
-			}
-			else {
-			  ret->tid = move(thread(responderThread, ret));
+			  }
+			  else {
+			    ret->tid = move(thread(responderThread, ret));
+			  }
 			}
 
 			auto states = g_dstates.getCopy();
diff --git a/pdns/dnsdist.cc b/pdns/dnsdist.cc
index dbefaa8599..150028ce07 100644
--- a/pdns/dnsdist.cc
+++ b/pdns/dnsdist.cc
@@ -472,7 +472,13 @@ DownstreamState::DownstreamState(const ComboAddress& remote_, const ComboAddress
       SSetsockopt(fd, SOL_SOCKET, SO_REUSEADDR, 1);
       SBind(fd, sourceAddr);
     }
-    SConnect(fd, remote);
+    try {
+      SConnect(fd, remote);
+      connected = true;
+    }
+    catch(const std::runtime_error& error) {
+      infolog("Error connecting to new server with address %s: %s", remote.toStringWithPort(), error.what());
+    }
     idStates.resize(g_maxOutstanding);
     sw.start();
     infolog("Added downstream server %s", remote.toStringWithPort());
@@ -1271,6 +1277,18 @@ void* healthChecksThread()
 
         if(newState != dss->upStatus) {
           warnlog("Marking downstream %s as '%s'", dss->getNameWithAddr(), newState ? "up" : "down");
+
+          if (newState && !dss->connected) {
+            try {
+              SConnect(dss->fd, dss->remote);
+              dss->connected = true;
+              dss->tid = move(thread(responderThread, dss));
+            }
+            catch(const std::runtime_error& error) {
+              infolog("Error connecting to new server with address %s: %s", dss->remote.toStringWithPort(), error.what());
+            }
+          }
+
           dss->upStatus = newState;
           dss->currentCheckFailures = 0;
         }
@@ -1871,7 +1889,9 @@ try
     for(const auto& address : g_cmdLine.remotes) {
       auto ret=std::make_shared<DownstreamState>(ComboAddress(address, 53));
       addServerToPool(localPools, "", ret);
-      ret->tid = move(thread(responderThread, ret));
+      if (ret->connected) {
+        ret->tid = move(thread(responderThread, ret));
+      }
       g_dstates.modify([ret](servers_t& servers) { servers.push_back(ret); });
     }
   }
diff --git a/pdns/dnsdist.hh b/pdns/dnsdist.hh
index 6e9538c1f5..8398c140a0 100644
--- a/pdns/dnsdist.hh
+++ b/pdns/dnsdist.hh
@@ -356,6 +356,7 @@ struct DownstreamState
   bool upStatus{false};
   bool useECS{false};
   bool setCD{false};
+  std::atomic<bool> connected{false};
   bool isUp() const
   {
     if(availability == Availability::Down)