[1539] make sure ddns forwarder establishes connection only once.

src/bin/auth/auth_srv.cc

@@ -110,6 +110,27 @@ public:
 private:
     MessageRenderer& renderer_;
 };
+
+/// TBD document it.
+class SocketSessionForwarderHolder {
+public:
+    SocketSessionForwarderHolder(BaseSocketSessionForwarder& forwarder) :
+        forwarder_(forwarder), connected_(false)
+    {}
+    ~SocketSessionForwarderHolder() {}
+
+    void connect() {
+        if (!connected_) {
+            forwarder_.connectToReceiver();
+            connected_ = true;
+        }
+    }
+
+    BaseSocketSessionForwarder& forwarder_;
+
+private:
+    bool connected_;
+};
 }
 
 class AuthSrvImpl {
@@ -196,7 +217,7 @@ private:
     bool xfrout_connected_;
     AbstractXfroutClient& xfrout_client_;
 
-    BaseSocketSessionForwarder& ddns_forwarder_;
+    SocketSessionForwarderHolder ddns_forwarder_;
 
     /// Increment query counter
     void incCounter(const int protocol);
@@ -763,7 +784,8 @@ AuthSrvImpl::processUpdate(const IOMessage& /*io_message*/,
                            std::auto_ptr<TSIGContext> /*tsig_context*/)
 {
     // hardcode for initial test
-    ddns_forwarder_.connectToReceiver();
+    ddns_forwarder_.connect();
+
     return (false);
 }
 

src/bin/auth/tests/auth_srv_unittest.cc

@@ -1392,14 +1392,19 @@ TEST_F(AuthSrvTest, queryWithThrowingInToWire) {
 TEST_F(AuthSrvTest, DDNSForward) {
     EXPECT_FALSE(ddns_forwarder.isConnected());
 
-    UnitTestUtil::createRequestMessage(request_message, Opcode::UPDATE(),
-                                       default_qid, Name("example.com"),
-                                       RRClass::IN(), RRType::SOA());
-    createRequestPacket(request_message, IPPROTO_UDP);
-    server.processMessage(*io_message, *parse_message, *response_obuffer,
-                          &dnsserv);
-    EXPECT_FALSE(dnsserv.hasAnswer());
-    EXPECT_TRUE(ddns_forwarder.isConnected());
+    // Repeat sending an update request two times.  By doing that we'll
+    // confirm the forwarder connection will be established exactly once,
+    // and kept established.
+    for (size_t i = 0; i < 2; ++i) {
+        UnitTestUtil::createRequestMessage(request_message, Opcode::UPDATE(),
+                                           default_qid, Name("example.com"),
+                                           RRClass::IN(), RRType::SOA());
+        createRequestPacket(request_message, IPPROTO_UDP);
+        server.processMessage(*io_message, *parse_message, *response_obuffer,
+                              &dnsserv);
+        EXPECT_FALSE(dnsserv.hasAnswer());
+        EXPECT_TRUE(ddns_forwarder.isConnected());
+    }
 }
 
 }

src/lib/testutils/mockups.h

@@ -218,6 +218,9 @@ public:
             isc_throw(isc::util::io::SocketSessionError, "socket session "
                       "forwarding connection disabled for test");
         }
+        if (is_connected_) {
+            isc_throw(isc::util::io::SocketSessionError, "duplicate connect");
+        }
         is_connected_ = true;
     }
     virtual void close() {}