net/dns/dns_transaction.h

   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 NET_DNS_DNS_TRANSACTION_H_
   6 #define NET_DNS_DNS_TRANSACTION_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "base/callback_forward.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "net/base/net_export.h"
  14
  15 namespace net {
  16
  17 class BoundNetLog;
  18 class DnsResponse;
  19 class DnsSession;
  20
  21 // DnsTransaction implements a stub DNS resolver as defined in RFC 1034.
  22 // The DnsTransaction takes care of retransmissions, name server fallback (or
  23 // round-robin), suffix search, and simple response validation ("does it match
  24 // the query") to fight poisoning.
  25 //
  26 // Destroying DnsTransaction cancels the underlying network effort.
  27 class NET_EXPORT_PRIVATE DnsTransaction {
  28  public:
  29   virtual ~DnsTransaction() {}
  30
  31   // Returns the original |hostname|.
  32   virtual const std::string& GetHostname() const = 0;
  33
  34   // Returns the |qtype|.
  35   virtual uint16 GetType() const = 0;
  36
  37   // Starts the transaction. Returns the net error on synchronous failure or
  38   // ERR_IO_PENDING in which case the result will be passed via the callback.
  39   // Can be called at most once.
  40   virtual int Start() = 0;
  41 };
  42
  43 // Creates DnsTransaction which performs asynchronous DNS search.
  44 // It does NOT perform caching, aggregation or prioritization of transactions.
  45 //
  46 // Destroying the factory does NOT affect any already created DnsTransactions.
  47 class NET_EXPORT_PRIVATE DnsTransactionFactory {
  48  public:
  49   // Called with the response or NULL if no matching response was received.
  50   // Note that the |GetDottedName()| of the response may be different than the
  51   // original |hostname| as a result of suffix search.
  52   typedef base::Callback<void(DnsTransaction* transaction,
  53                               int neterror,
  54                               const DnsResponse* response)> CallbackType;
  55
  56   virtual ~DnsTransactionFactory() {}
  57
  58   // Creates DnsTransaction for the given |hostname| and |qtype| (assuming
  59   // QCLASS is IN). |hostname| should be in the dotted form. A dot at the end
  60   // implies the domain name is fully-qualified and will be exempt from suffix
  61   // search. |hostname| should not be an IP literal.
  62   //
  63   // The transaction will run |callback| upon asynchronous completion.
  64   // The |net_log| is used as the parent log.
  65   virtual scoped_ptr<DnsTransaction> CreateTransaction(
  66       const std::string& hostname,
  67       uint16 qtype,
  68       const CallbackType& callback,
  69       const BoundNetLog& net_log) WARN_UNUSED_RESULT = 0;
  70
  71   // Creates a DnsTransactionFactory which creates DnsTransactionImpl using the
  72   // |session|.
  73   static scoped_ptr<DnsTransactionFactory> CreateFactory(
  74       DnsSession* session) WARN_UNUSED_RESULT;
  75 };
  76
  77 }  // namespace net
  78
  79 #endif  // NET_DNS_DNS_TRANSACTION_H_
  80