// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef REMOTING_HOST_DNS_BLACKHOLE_CHECKER_H_
#define REMOTING_HOST_DNS_BLACKHOLE_CHECKER_H_

#include "base/callback.h"
#include "base/macros.h"
namespace network {
class SharedURLLoaderFactory;
class SimpleURLLoader;
}  // namespace network

namespace remoting {

// This is the default prefix that is prepended to the kTalkGadgetUrl to form
// the complete talkgadget URL used by the host. Policy settings allow admins
// to change the prefix that is used.
extern const char kDefaultHostTalkGadgetPrefix[];

class DnsBlackholeChecker {
 public:
  DnsBlackholeChecker(
      scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory,
      std::string talkgadget_prefix);
  ~DnsBlackholeChecker();

  // Initiates a check the verify that the host talkgadget has not been "DNS
  // blackholed" to prevent connections. If this is called again before the
  // callback has been called, then the second call is ignored.
  void CheckForDnsBlackhole(const base::Callback<void(bool)>& callback);

 private:
  void OnURLLoadComplete(std::unique_ptr<std::string> response_body);

  // URL loader factory used to use to create the URL loader.
  scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory_;

  // URL loader used to verify access to the host talkgadget.
  std::unique_ptr<network::SimpleURLLoader> url_loader_;

  // The string pre-pended to '.talkgadget.google.com' to create the full
  // talkgadget domain name for the host.
  std::string talkgadget_prefix_;

  // Called with the results of the connection check.
  base::Callback<void(bool)> callback_;

  DISALLOW_COPY_AND_ASSIGN(DnsBlackholeChecker);
};

}  // namespace remoting

#endif  // REMOTING_HOST_DNS_BLACKHOLE_CHECKER_H_