Make all the DnsTls headers private to libnetd_resolv

Test: m libnetd_resolv netd
Test: atest resolv_integration_test
Change-Id: Icae95641733abe7fe86b903dd3bcf69b08c83285
diff --git a/resolv/DnsTlsSocketFactory.h b/resolv/DnsTlsSocketFactory.h
new file mode 100644
index 0000000..af4011d
--- /dev/null
+++ b/resolv/DnsTlsSocketFactory.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _DNS_DNSTLSSOCKETFACTORY_H
+#define _DNS_DNSTLSSOCKETFACTORY_H
+
+#include <memory>
+
+#include "DnsTlsSocket.h"
+#include "IDnsTlsSocketFactory.h"
+
+namespace android {
+namespace net {
+
+class IDnsTlsSocketObserver;
+class DnsTlsSessionCache;
+struct DnsTlsServer;
+
+// Trivial RAII factory for DnsTlsSocket.  This is owned by DnsTlsDispatcher.
+class DnsTlsSocketFactory : public IDnsTlsSocketFactory {
+  public:
+    std::unique_ptr<IDnsTlsSocket> createDnsTlsSocket(const DnsTlsServer& server, unsigned mark,
+                                                      IDnsTlsSocketObserver* _Nonnull observer,
+                                                      DnsTlsSessionCache* _Nonnull cache) override {
+        auto socket = std::make_unique<DnsTlsSocket>(server, mark, observer, cache);
+        if (!socket->initialize()) {
+            return nullptr;
+        }
+        return std::move(socket);
+    }
+};
+
+}  // end of namespace net
+}  // end of namespace android
+
+#endif  // _DNS_DNSTLSSOCKETFACTORY_H