1// Copyright (c) 2012 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef REMOTING_HOST_DNS_BLACKHOLE_CHECKER_H_ 6#define REMOTING_HOST_DNS_BLACKHOLE_CHECKER_H_ 7 8#include "net/url_request/url_fetcher_delegate.h" 9 10#include "base/callback.h" 11 12namespace net { 13class URLRequestContextGetter; 14} // namespace net 15 16namespace remoting { 17 18// This is the default prefix that is prepended to the kTalkGadgetUrl to form 19// the complete talkgadget URL used by the host. Policy settings allow admins 20// to change the prefix that is used. 21extern const char kDefaultHostTalkGadgetPrefix[]; 22 23class DnsBlackholeChecker : public net::URLFetcherDelegate { 24 public: 25 DnsBlackholeChecker( 26 scoped_refptr<net::URLRequestContextGetter> url_request_context_getter, 27 std::string talkgadget_prefix); 28 virtual ~DnsBlackholeChecker(); 29 30 // net::URLFetcherDelegate interface. 31 virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE; 32 33 // Initiates a check the verify that the host talkgadget has not been "DNS 34 // blackholed" to prevent connections. If this is called again before the 35 // callback has been called, then the second call is ignored. 36 void CheckForDnsBlackhole(const base::Callback<void(bool)>& callback); 37 38 private: 39 // URL request context getter to use to create the URL fetcher. 40 scoped_refptr<net::URLRequestContextGetter> url_request_context_getter_; 41 42 // URL fetcher used to verify access to the host talkgadget. 43 scoped_ptr<net::URLFetcher> url_fetcher_; 44 45 // The string pre-pended to '.talkgadget.google.com' to create the full 46 // talkgadget domain name for the host. 47 std::string talkgadget_prefix_; 48 49 // Called with the results of the connection check. 50 base::Callback<void(bool)> callback_; 51 52 DISALLOW_COPY_AND_ASSIGN(DnsBlackholeChecker); 53}; 54 55} // namespace remoting 56 57#endif // REMOTING_HOST_DNS_BLACKHOLE_CHECKER_H_ 58