tools: Refactoring ndn-autoconfig implementation

Change-Id: Ib92942ba40f04aaee83479177b9ba5d32a09af04
Refs: #2421
diff --git a/tools/ndn-autoconfig/base-dns.hpp b/tools/ndn-autoconfig/base-dns.hpp
new file mode 100644
index 0000000..1b881ba
--- /dev/null
+++ b/tools/ndn-autoconfig/base-dns.hpp
@@ -0,0 +1,85 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2015,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NFD_TOOLS_NDN_AUTOCONFIG_BASE_DNS_HPP
+#define NFD_TOOLS_NDN_AUTOCONFIG_BASE_DNS_HPP
+
+#include "base.hpp"
+
+namespace ndn {
+namespace tools {
+namespace autoconfig {
+
+/**
+ * @brief Base class for stages that use DNS-based guessing
+ */
+class BaseDns : public Base
+{
+protected:
+  class Error : public std::runtime_error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : std::runtime_error(what)
+    {
+    }
+  };
+
+  BaseDns(Face& face, KeyChain& keyChain, const NextStageCallback& nextStageOnFailure);
+
+  /**
+   * @brief Send DNS SRV request for a @p fqdn fully qualified domain name
+   * @return FaceUri of the hub from the requested SRV record
+   * @throw Error if query returns nothing or SRV record cannot be parsed
+   */
+  std::string
+  querySrvRr(const std::string& fqdn);
+
+  /**
+   * @brief Send DNS SRV request using search domain list
+   * @return FaceUri of the hub from the requested SRV record
+   * @throw Error if query returns nothing or SRV record cannot be parsed
+   */
+  std::string
+  querySrvRrSearch();
+
+private:
+  union QueryAnswer;
+
+  /**
+   * @brief Parse SRV record
+   * @return FaceUri of the hub from the SRV record
+   * @throw Error if SRV record cannot be parsed
+   */
+  std::string
+  parseSrvRr(const QueryAnswer& queryAnswer, int answerSize);
+};
+
+} // namespace autoconfig
+} // namespace tools
+} // namespace ndn
+
+#endif // NFD_TOOLS_NDN_AUTOCONFIG_BASE_DNS_HPP