tools/ndn-autoconfig.cpp - ndnSIM - Gitiles

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
  * Copyright (c) 2014,  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/>.
  */

 #include "version.hpp"

 #include "core/face-uri.hpp"

 #include <ndn-cxx/face.hpp>
 #include <ndn-cxx/management/nfd-controller.hpp>
 #include <ndn-cxx/management/nfd-face-status.hpp>
 #include <ndn-cxx/security/key-chain.hpp>
 #include <ndn-cxx/encoding/buffer-stream.hpp>

 #include <boost/lexical_cast.hpp>

 #include <sys/types.h>
 #include <netinet/in.h>
 #include <arpa/nameser.h>
 #include <resolv.h>

 #ifdef __APPLE__
 #include <arpa/nameser_compat.h>
 #endif

 namespace ndn {
 namespace tools {

 void
 usage(const char* programName)
 {
   std::cout << "Usage:\n" << programName  << " [-h] [-V]\n"
             << "   -h  - print usage and exit\n"
             << "   -V  - print version number and exit\n"
             << std::endl;
 }

 class NdnAutoconfig
 {
 public:
   union QueryAnswer
   {
     HEADER header;
     uint8_t buf[NS_PACKETSZ];
   };

   class Error : public std::runtime_error
   {
   public:
     explicit
     Error(const std::string& what)
       : std::runtime_error(what)
     {
     }
   };

   explicit
   NdnAutoconfig()
     : m_controller(m_face)
   {
   }

   void
   run()
   {
     m_face.processEvents();
   }

   void
   fetchSegments(const Data& data, const shared_ptr<OBufferStream>& buffer,
                 void (NdnAutoconfig::*onDone)(const shared_ptr<OBufferStream>&))
   {
     buffer->write(reinterpret_cast<const char*>(data.getContent().value()),
                   data.getContent().value_size());

     uint64_t currentSegment = data.getName().get(-1).toSegment();

     const name::Component& finalBlockId = data.getMetaInfo().getFinalBlockId();
     if (finalBlockId.empty() ||
         finalBlockId.toSegment() > currentSegment)
       {
         m_face.expressInterest(data.getName().getPrefix(-1).appendSegment(currentSegment+1),
                                bind(&NdnAutoconfig::fetchSegments, this, _2, buffer, onDone),
                                bind(&NdnAutoconfig::discoverHubStage2, this, "Timeout"));
       }
     else
       {
         return (this->*onDone)(buffer);
       }
   }

   void
   discoverHubStage1()
   {
     shared_ptr<OBufferStream> buffer = make_shared<OBufferStream>();

     Interest interest("/localhost/nfd/faces/list");
     interest.setChildSelector(1);
     interest.setMustBeFresh(true);

     m_face.expressInterest(interest,
                            bind(&NdnAutoconfig::fetchSegments, this, _2, buffer,
                                 &NdnAutoconfig::discoverHubStage1_registerLocalhubNdnAutoconfHub),
                            bind(&NdnAutoconfig::discoverHubStage2, this, "Timeout"));
   }

   void
   discoverHubStage1_registerLocalhubNdnAutoconfHub(const shared_ptr<OBufferStream>& buffer)
   {
     ConstBufferPtr buf = buffer->buf();
     std::vector<uint64_t> multicastFaces;

     size_t offset = 0;
     while (offset < buf->size())
       {
         Block block;
         bool ok = Block::fromBuffer(buf, offset, block);
         if (!ok)
           {
             std::cerr << "ERROR: cannot decode FaceStatus TLV" << std::endl;
             break;
           }

         offset += block.size();

         nfd::FaceStatus faceStatus(block);

         ::nfd::FaceUri uri(faceStatus.getRemoteUri());
         if (uri.getScheme() == "udp4") {
           namespace ip = boost::asio::ip;
           boost::system::error_code ec;
           ip::address address = ip::address::from_string(uri.getHost(), ec);

           if (!ec && address.is_multicast()) {
             multicastFaces.push_back(faceStatus.getFaceId());
           }
           else
             continue;
         }
       }

     if (multicastFaces.empty()) {
       discoverHubStage2("No multicast faces available, skipping stage 1");
     }
     else {
       shared_ptr<nfd::Controller> controller = make_shared<nfd::Controller>(ref(m_face));
       shared_ptr<std::pair<size_t, size_t> > nRegistrations =
         make_shared<std::pair<size_t, size_t> >(0, 0);

       nfd::ControlParameters parameters;
       parameters
         .setName("/localhop/ndn-autoconf/hub")
         .setCost(1);

       nRegistrations->first = multicastFaces.size();

       for (std::vector<uint64_t>::iterator i = multicastFaces.begin();
            i != multicastFaces.end(); ++i) {
         parameters.setFaceId(*i);

         controller->start<nfd::RibRegisterCommand>(parameters,
           bind(&NdnAutoconfig::discoverHubStage1_onRegisterSuccess,
                this, controller, nRegistrations),
           bind(&NdnAutoconfig::discoverHubStage1_onRegisterFailure,
                this, _1, _2, controller, nRegistrations));
       }
     }
   }

   void
   discoverHubStage1_onRegisterSuccess(const shared_ptr<nfd::Controller>& controller,
                                       const shared_ptr<std::pair<size_t, size_t> >& nRegistrations)
   {
     nRegistrations->second++;

     if (nRegistrations->first == nRegistrations->second) {
       discoverHubStage1_requestHubData();
     }
   }

   void
   discoverHubStage1_onRegisterFailure(uint32_t code, const std::string& error,
                                       const shared_ptr<nfd::Controller> controller,
                                       const shared_ptr<std::pair<size_t, size_t> >& nRegistrations)
   {
     std::cerr << "ERROR: " << error << " (code: " << code << ")" << std::endl;
     nRegistrations->first--;

     if (nRegistrations->first == nRegistrations->second) {
       if (nRegistrations->first > 0) {
         discoverHubStage1_requestHubData();
       } else {
         discoverHubStage2("Failed to register /localhop/ndn-autoconf/hub for all multicast faces");
       }
     }
   }

   // Start to look for a hub (NDN hub discovery first stage)
   void
   discoverHubStage1_requestHubData()
   {
     Interest interest(Name("/localhop/ndn-autoconf/hub"));
     interest.setInterestLifetime(time::milliseconds(4000)); // 4 seconds
     interest.setMustBeFresh(true);

     std::cerr << "Stage 1: Trying multicast discovery..." << std::endl;
     m_face.expressInterest(interest,
                            bind(&NdnAutoconfig::onDiscoverHubStage1Success, this, _1, _2),
                            bind(&NdnAutoconfig::discoverHubStage2, this, "Timeout"));
   }

   // First stage OnData Callback
   void
   onDiscoverHubStage1Success(const Interest& interest, Data& data)
   {
     const Block& content = data.getContent();
     content.parse();

     // Get Uri
     Block::element_const_iterator blockValue = content.find(tlv::nfd::Uri);
     if (blockValue == content.elements_end())
     {
       discoverHubStage2("Incorrect reply to stage1");
       return;
     }
     std::string faceMgmtUri(reinterpret_cast<const char*>(blockValue->value()),
                             blockValue->value_size());
     connectToHub(faceMgmtUri);
   }

   // First stage OnTimeout callback - start 2nd stage
   void
   discoverHubStage2(const std::string& message)
   {
     std::cerr << message << std::endl;
     std::cerr << "Stage 2: Trying DNS query with default suffix..." << std::endl;

     _res.retry = 2;
     _res.ndots = 10;

     QueryAnswer queryAnswer;

     int answerSize = res_search("_ndn._udp",
                                 ns_c_in,
                                 ns_t_srv,
                                 queryAnswer.buf,
                                 sizeof(queryAnswer));

     // 2nd stage failed - move on to the third stage
     if (answerSize < 0)
     {
       discoverHubStage3("Failed to find NDN router using default suffix DNS query");
     }
     else
     {
       bool isParsed = parseHostAndConnectToHub(queryAnswer, answerSize);
       if (isParsed == false)
       {
         // Failed to parse DNS response, try stage 3
         discoverHubStage3("Failed to parse DNS response");
       }
     }
   }

   // Second stage OnTimeout callback
   void
   discoverHubStage3(const std::string& message)
   {
     std::cerr << message << std::endl;
     std::cerr << "Stage 3: Trying to find home router..." << std::endl;

     KeyChain keyChain;
     Name identity = keyChain.getDefaultIdentity();
     std::string serverName = "_ndn._udp.";

     for (Name::const_reverse_iterator i = identity.rbegin(); i != identity.rend(); i++)
     {
       serverName.append(i->toUri());
       serverName.append(".");
     }
     serverName += "_homehub._autoconf.named-data.net";
     std::cerr << "Stage3: About to query for a home router: " << serverName << std::endl;

     QueryAnswer queryAnswer;

     int answerSize = res_query(serverName.c_str(),
                                ns_c_in,
                                ns_t_srv,
                                queryAnswer.buf,
                                sizeof(queryAnswer));


     // 3rd stage failed - abort
     if (answerSize < 0)
     {
       std::cerr << "Failed to find a home router" << std::endl;
       std::cerr << "exit" << std::endl;
     }
     else
     {
       bool isParsed = parseHostAndConnectToHub(queryAnswer, answerSize);
       if (isParsed == false)
       {
         // Failed to parse DNS response
         throw Error("Failed to parse DNS response");
       }
     }

   }

   void
   connectToHub(const std::string& uri)
   {
     std::cerr << "about to connect to: " << uri << std::endl;

     m_controller.start<nfd::FaceCreateCommand>(
       nfd::ControlParameters()
         .setUri(uri),
       bind(&NdnAutoconfig::onHubConnectSuccess, this, _1),
       bind(&NdnAutoconfig::onHubConnectError, this, _1, _2)
     );
   }

   void
   onHubConnectSuccess(const nfd::ControlParameters& resp)
   {
     std::cerr << "Successfully created face: " << resp << std::endl;

     // Register a prefix in RIB
     nfd::ControlParameters ribParameters;
     ribParameters
       .setName("/ndn")
       .setFaceId(resp.getFaceId());

     m_controller.start<nfd::RibRegisterCommand>(
       ribParameters,
       bind(&NdnAutoconfig::onPrefixRegistrationSuccess, this, _1),
       bind(&NdnAutoconfig::onPrefixRegistrationError, this, _1, _2));
   }

   void
   onHubConnectError(uint32_t code, const std::string& error)
   {
     std::ostringstream os;
     os << "Failed to create face: " << error << " (code: " << code << ")";
     throw Error(os.str());
   }


   bool parseHostAndConnectToHub(QueryAnswer& queryAnswer, int answerSize)
   {
     // The references of the next classes are:
     // http://www.diablotin.com/librairie/networking/dnsbind/ch14_02.htm
     // https://gist.github.com/mologie/6027597

     struct rechdr
     {
       uint16_t type;
       uint16_t iclass;
       uint32_t ttl;
       uint16_t length;
     };

     struct srv_t
     {
       uint16_t priority;
       uint16_t weight;
       uint16_t port;
       uint8_t* target;
     };

     if (ntohs(queryAnswer.header.ancount) == 0)
     {
       std::cerr << "No records found\n" << std::endl;
       return false;
     }

     uint8_t* blob = queryAnswer.buf + NS_HFIXEDSZ;

     blob += dn_skipname(blob, queryAnswer.buf + answerSize) + NS_QFIXEDSZ;

     for (int i = 0; i < ntohs(queryAnswer.header.ancount); i++)
     {
       char srvName[NS_MAXDNAME];
       int serverNameSize = dn_expand(queryAnswer.buf,               // message pointer
                                      queryAnswer.buf + answerSize,  // end of message
                                      blob,                          // compressed server name
                                      srvName,                       // expanded server name
                                      NS_MAXDNAME);
       if (serverNameSize < 0)
       {
         return false;
       }

       srv_t* server = reinterpret_cast<srv_t*>(&blob[sizeof(rechdr)]);
       uint16_t convertedPort = be16toh(server->port);

       blob += serverNameSize + NS_HFIXEDSZ + NS_QFIXEDSZ;

       char hostName[NS_MAXDNAME];
       int hostNameSize = dn_expand(queryAnswer.buf,               // message pointer
                                    queryAnswer.buf + answerSize,  // end of message
                                    blob,                          // compressed host name
                                    hostName,                      // expanded host name
                                    NS_MAXDNAME);
       if (hostNameSize < 0)
       {
         return false;
       }

       std::string uri = "udp://";
       uri.append(hostName);
       uri.append(":");
       uri.append(boost::lexical_cast<std::string>(convertedPort));

       connectToHub(uri);
       return true;
     }

     return false;
   }

   void
   onPrefixRegistrationSuccess(const nfd::ControlParameters& commandSuccessResult)
   {
     std::cerr << "Successful in name registration: " << commandSuccessResult << std::endl;
   }

   void
   onPrefixRegistrationError(uint32_t code, const std::string& error)
   {
     std::ostringstream os;
     os << "Failed in name registration, " << error << " (code: " << code << ")";
     throw Error(os.str());
   }

 private:
   Face m_face;
   nfd::Controller m_controller;
 };

 } // namespace tools
 } // namespace ndn

 int
 main(int argc, char** argv)
 {
   int opt;
   const char* programName = argv[0];

   while ((opt = getopt(argc, argv, "hV")) != -1) {
     switch (opt) {
     case 'h':
       ndn::tools::usage(programName);
       return 0;
     case 'V':
       std::cout << NFD_VERSION_BUILD_STRING << std::endl;
       return 0;
     }
   }

   try {
     ndn::tools::NdnAutoconfig autoConfigInstance;

     autoConfigInstance.discoverHubStage1();
     autoConfigInstance.run();
   }
   catch (const std::exception& error) {
     std::cerr << "ERROR: " << error.what() << std::endl;
     return 1;
   }
   return 0;
 }
	/* -- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -- */
	/**
	* Copyright (c) 2014, 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/>.
	*/

	#include "version.hpp"

	#include "core/face-uri.hpp"

	#include <ndn-cxx/face.hpp>
	#include <ndn-cxx/management/nfd-controller.hpp>
	#include <ndn-cxx/management/nfd-face-status.hpp>
	#include <ndn-cxx/security/key-chain.hpp>
	#include <ndn-cxx/encoding/buffer-stream.hpp>

	#include <boost/lexical_cast.hpp>

	#include <sys/types.h>
	#include <netinet/in.h>
	#include <arpa/nameser.h>
	#include <resolv.h>

	#ifdef __APPLE__
	#include <arpa/nameser_compat.h>
	#endif

	namespace ndn {
	namespace tools {

	void
	usage(const char* programName)
	{
	std::cout << "Usage:\n" << programName << " [-h] [-V]\n"
	<< " -h - print usage and exit\n"
	<< " -V - print version number and exit\n"
	<< std::endl;
	}

	class NdnAutoconfig
	{
	public:
	union QueryAnswer
	{
	HEADER header;
	uint8_t buf[NS_PACKETSZ];
	};

	class Error : public std::runtime_error
	{
	public:
	explicit
	Error(const std::string& what)
	: std::runtime_error(what)
	{
	}
	};

	explicit
	NdnAutoconfig()
	: m_controller(m_face)
	{
	}

	void
	run()
	{
	m_face.processEvents();
	}

	void
	fetchSegments(const Data& data, const shared_ptr<OBufferStream>& buffer,
	void (NdnAutoconfig::*onDone)(const shared_ptr<OBufferStream>&))
	{
	buffer->write(reinterpret_cast<const char*>(data.getContent().value()),
	data.getContent().value_size());

	uint64_t currentSegment = data.getName().get(-1).toSegment();

	const name::Component& finalBlockId = data.getMetaInfo().getFinalBlockId();
	if (finalBlockId.empty() \|\|
	finalBlockId.toSegment() > currentSegment)
	{
	m_face.expressInterest(data.getName().getPrefix(-1).appendSegment(currentSegment+1),
	bind(&NdnAutoconfig::fetchSegments, this, _2, buffer, onDone),
	bind(&NdnAutoconfig::discoverHubStage2, this, "Timeout"));
	}
	else
	{
	return (this->*onDone)(buffer);
	}
	}

	void
	discoverHubStage1()
	{
	shared_ptr<OBufferStream> buffer = make_shared<OBufferStream>();

	Interest interest("/localhost/nfd/faces/list");
	interest.setChildSelector(1);
	interest.setMustBeFresh(true);

	m_face.expressInterest(interest,
	bind(&NdnAutoconfig::fetchSegments, this, _2, buffer,
	&NdnAutoconfig::discoverHubStage1_registerLocalhubNdnAutoconfHub),
	bind(&NdnAutoconfig::discoverHubStage2, this, "Timeout"));
	}

	void
	discoverHubStage1_registerLocalhubNdnAutoconfHub(const shared_ptr<OBufferStream>& buffer)
	{
	ConstBufferPtr buf = buffer->buf();
	std::vector<uint64_t> multicastFaces;

	size_t offset = 0;
	while (offset < buf->size())
	{
	Block block;
	bool ok = Block::fromBuffer(buf, offset, block);
	if (!ok)
	{
	std::cerr << "ERROR: cannot decode FaceStatus TLV" << std::endl;
	break;
	}

	offset += block.size();

	nfd::FaceStatus faceStatus(block);

	::nfd::FaceUri uri(faceStatus.getRemoteUri());
	if (uri.getScheme() == "udp4") {
	namespace ip = boost::asio::ip;
	boost::system::error_code ec;
	ip::address address = ip::address::from_string(uri.getHost(), ec);

	if (!ec && address.is_multicast()) {
	multicastFaces.push_back(faceStatus.getFaceId());
	}
	else
	continue;
	}
	}

	if (multicastFaces.empty()) {
	discoverHubStage2("No multicast faces available, skipping stage 1");
	}
	else {
	shared_ptr<nfd::Controller> controller = make_shared<nfd::Controller>(ref(m_face));
	shared_ptr<std::pair<size_t, size_t> > nRegistrations =
	make_shared<std::pair<size_t, size_t> >(0, 0);

	nfd::ControlParameters parameters;
	parameters
	.setName("/localhop/ndn-autoconf/hub")
	.setCost(1);

	nRegistrations->first = multicastFaces.size();

	for (std::vector<uint64_t>::iterator i = multicastFaces.begin();
	i != multicastFaces.end(); ++i) {
	parameters.setFaceId(*i);

	controller->start<nfd::RibRegisterCommand>(parameters,
	bind(&NdnAutoconfig::discoverHubStage1_onRegisterSuccess,
	this, controller, nRegistrations),
	bind(&NdnAutoconfig::discoverHubStage1_onRegisterFailure,
	this, _1, _2, controller, nRegistrations));
	}
	}
	}

	void
	discoverHubStage1_onRegisterSuccess(const shared_ptr<nfd::Controller>& controller,
	const shared_ptr<std::pair<size_t, size_t> >& nRegistrations)
	{
	nRegistrations->second++;

	if (nRegistrations->first == nRegistrations->second) {
	discoverHubStage1_requestHubData();
	}
	}

	void
	discoverHubStage1_onRegisterFailure(uint32_t code, const std::string& error,
	const shared_ptr<nfd::Controller> controller,
	const shared_ptr<std::pair<size_t, size_t> >& nRegistrations)
	{
	std::cerr << "ERROR: " << error << " (code: " << code << ")" << std::endl;
	nRegistrations->first--;

	if (nRegistrations->first == nRegistrations->second) {
	if (nRegistrations->first > 0) {
	discoverHubStage1_requestHubData();
	} else {
	discoverHubStage2("Failed to register /localhop/ndn-autoconf/hub for all multicast faces");
	}
	}
	}

	// Start to look for a hub (NDN hub discovery first stage)
	void
	discoverHubStage1_requestHubData()
	{
	Interest interest(Name("/localhop/ndn-autoconf/hub"));
	interest.setInterestLifetime(time::milliseconds(4000)); // 4 seconds
	interest.setMustBeFresh(true);

	std::cerr << "Stage 1: Trying multicast discovery..." << std::endl;
	m_face.expressInterest(interest,
	bind(&NdnAutoconfig::onDiscoverHubStage1Success, this, _1, _2),
	bind(&NdnAutoconfig::discoverHubStage2, this, "Timeout"));
	}

	// First stage OnData Callback
	void
	onDiscoverHubStage1Success(const Interest& interest, Data& data)
	{
	const Block& content = data.getContent();
	content.parse();

	// Get Uri
	Block::element_const_iterator blockValue = content.find(tlv::nfd::Uri);
	if (blockValue == content.elements_end())
	{
	discoverHubStage2("Incorrect reply to stage1");
	return;
	}
	std::string faceMgmtUri(reinterpret_cast<const char*>(blockValue->value()),
	blockValue->value_size());
	connectToHub(faceMgmtUri);
	}

	// First stage OnTimeout callback - start 2nd stage
	void
	discoverHubStage2(const std::string& message)
	{
	std::cerr << message << std::endl;
	std::cerr << "Stage 2: Trying DNS query with default suffix..." << std::endl;

	_res.retry = 2;
	_res.ndots = 10;

	QueryAnswer queryAnswer;

	int answerSize = res_search("_ndn._udp",
	ns_c_in,
	ns_t_srv,
	queryAnswer.buf,
	sizeof(queryAnswer));

	// 2nd stage failed - move on to the third stage
	if (answerSize < 0)
	{
	discoverHubStage3("Failed to find NDN router using default suffix DNS query");
	}
	else
	{
	bool isParsed = parseHostAndConnectToHub(queryAnswer, answerSize);
	if (isParsed == false)
	{
	// Failed to parse DNS response, try stage 3
	discoverHubStage3("Failed to parse DNS response");
	}
	}
	}

	// Second stage OnTimeout callback
	void
	discoverHubStage3(const std::string& message)
	{
	std::cerr << message << std::endl;
	std::cerr << "Stage 3: Trying to find home router..." << std::endl;

	KeyChain keyChain;
	Name identity = keyChain.getDefaultIdentity();
	std::string serverName = "_ndn._udp.";

	for (Name::const_reverse_iterator i = identity.rbegin(); i != identity.rend(); i++)
	{
	serverName.append(i->toUri());
	serverName.append(".");
	}
	serverName += "_homehub._autoconf.named-data.net";
	std::cerr << "Stage3: About to query for a home router: " << serverName << std::endl;

	QueryAnswer queryAnswer;

	int answerSize = res_query(serverName.c_str(),
	ns_c_in,
	ns_t_srv,
	queryAnswer.buf,
	sizeof(queryAnswer));


	// 3rd stage failed - abort
	if (answerSize < 0)
	{
	std::cerr << "Failed to find a home router" << std::endl;
	std::cerr << "exit" << std::endl;
	}
	else
	{
	bool isParsed = parseHostAndConnectToHub(queryAnswer, answerSize);
	if (isParsed == false)
	{
	// Failed to parse DNS response
	throw Error("Failed to parse DNS response");
	}
	}

	}

	void
	connectToHub(const std::string& uri)
	{
	std::cerr << "about to connect to: " << uri << std::endl;

	m_controller.start<nfd::FaceCreateCommand>(
	nfd::ControlParameters()
	.setUri(uri),
	bind(&NdnAutoconfig::onHubConnectSuccess, this, _1),
	bind(&NdnAutoconfig::onHubConnectError, this, _1, _2)
	);
	}

	void
	onHubConnectSuccess(const nfd::ControlParameters& resp)
	{
	std::cerr << "Successfully created face: " << resp << std::endl;

	// Register a prefix in RIB
	nfd::ControlParameters ribParameters;
	ribParameters
	.setName("/ndn")
	.setFaceId(resp.getFaceId());

	m_controller.start<nfd::RibRegisterCommand>(
	ribParameters,
	bind(&NdnAutoconfig::onPrefixRegistrationSuccess, this, _1),
	bind(&NdnAutoconfig::onPrefixRegistrationError, this, _1, _2));
	}

	void
	onHubConnectError(uint32_t code, const std::string& error)
	{
	std::ostringstream os;
	os << "Failed to create face: " << error << " (code: " << code << ")";
	throw Error(os.str());
	}


	bool parseHostAndConnectToHub(QueryAnswer& queryAnswer, int answerSize)
	{
	// The references of the next classes are:
	// http://www.diablotin.com/librairie/networking/dnsbind/ch14_02.htm
	// https://gist.github.com/mologie/6027597

	struct rechdr
	{
	uint16_t type;
	uint16_t iclass;
	uint32_t ttl;
	uint16_t length;
	};

	struct srv_t
	{
	uint16_t priority;
	uint16_t weight;
	uint16_t port;
	uint8_t* target;
	};

	if (ntohs(queryAnswer.header.ancount) == 0)
	{
	std::cerr << "No records found\n" << std::endl;
	return false;
	}

	uint8_t* blob = queryAnswer.buf + NS_HFIXEDSZ;

	blob += dn_skipname(blob, queryAnswer.buf + answerSize) + NS_QFIXEDSZ;

	for (int i = 0; i < ntohs(queryAnswer.header.ancount); i++)
	{
	char srvName[NS_MAXDNAME];
	int serverNameSize = dn_expand(queryAnswer.buf, // message pointer
	queryAnswer.buf + answerSize, // end of message
	blob, // compressed server name
	srvName, // expanded server name
	NS_MAXDNAME);
	if (serverNameSize < 0)
	{
	return false;
	}

	srv_t* server = reinterpret_cast<srv_t*>(&blob[sizeof(rechdr)]);
	uint16_t convertedPort = be16toh(server->port);

	blob += serverNameSize + NS_HFIXEDSZ + NS_QFIXEDSZ;

	char hostName[NS_MAXDNAME];
	int hostNameSize = dn_expand(queryAnswer.buf, // message pointer
	queryAnswer.buf + answerSize, // end of message
	blob, // compressed host name
	hostName, // expanded host name
	NS_MAXDNAME);
	if (hostNameSize < 0)
	{
	return false;
	}

	std::string uri = "udp://";
	uri.append(hostName);
	uri.append(":");
	uri.append(boost::lexical_cast<std::string>(convertedPort));

	connectToHub(uri);
	return true;
	}

	return false;
	}

	void
	onPrefixRegistrationSuccess(const nfd::ControlParameters& commandSuccessResult)
	{
	std::cerr << "Successful in name registration: " << commandSuccessResult << std::endl;
	}

	void
	onPrefixRegistrationError(uint32_t code, const std::string& error)
	{
	std::ostringstream os;
	os << "Failed in name registration, " << error << " (code: " << code << ")";
	throw Error(os.str());
	}

	private:
	Face m_face;
	nfd::Controller m_controller;
	};

	} // namespace tools
	} // namespace ndn

	int
	main(int argc, char** argv)
	{
	int opt;
	const char* programName = argv[0];

	while ((opt = getopt(argc, argv, "hV")) != -1) {
	switch (opt) {
	case 'h':
	ndn::tools::usage(programName);
	return 0;
	case 'V':
	std::cout << NFD_VERSION_BUILD_STRING << std::endl;
	return 0;
	}
	}

	try {
	ndn::tools::NdnAutoconfig autoConfigInstance;

	autoConfigInstance.discoverHubStage1();
	autoConfigInstance.run();
	}
	catch (const std::exception& error) {
	std::cerr << "ERROR: " << error.what() << std::endl;
	return 1;
	}
	return 0;
	}