net/dns/mdns_client.h

   1 // Copyright 2013 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_MDNS_CLIENT_H_
   6 #define NET_DNS_MDNS_CLIENT_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/callback.h"
  12 #include "net/base/ip_endpoint.h"
  13 #include "net/dns/dns_query.h"
  14 #include "net/dns/dns_response.h"
  15 #include "net/dns/record_parsed.h"
  16
  17 namespace net {
  18
  19 class RecordParsed;
  20
  21 // Represents a one-time record lookup. A transaction takes one
  22 // associated callback (see |MDnsClient::CreateTransaction|) and calls it
  23 // whenever a matching record has been found, either from the cache or
  24 // by querying the network (it may choose to query either or both based on its
  25 // creation flags, see MDnsTransactionFlags). Network-based transactions will
  26 // time out after a reasonable number of seconds.
  27 class NET_EXPORT MDnsTransaction {
  28  public:
  29   // Used to signify what type of result the transaction has recieved.
  30   enum Result {
  31     // Passed whenever a record is found.
  32     RESULT_RECORD,
  33     // The transaction is done. Applies to non-single-valued transactions. Is
  34     // called when the transaction has finished (this is the last call to the
  35     // callback).
  36     RESULT_DONE,
  37     // No results have been found. Applies to single-valued transactions. Is
  38     // called when the transaction has finished without finding any results.
  39     // For transactions that use the network, this happens when a timeout
  40     // occurs, for transactions that are cache-only, this happens when no
  41     // results are in the cache.
  42     RESULT_NO_RESULTS,
  43     // Called when an NSec record is read for this transaction's
  44     // query. This means there cannot possibly be a record of the type
  45     // and name for this transaction.
  46     RESULT_NSEC
  47   };
  48
  49   // Used when creating an MDnsTransaction.
  50   enum Flags {
  51     // Transaction should return only one result, and stop listening after it.
  52     // Note that single result transactions will signal when their timeout is
  53     // reached, whereas multi-result transactions will not.
  54     SINGLE_RESULT = 1 << 0,
  55     // Query the cache or the network. May both be used. One must be present.
  56     QUERY_CACHE = 1 << 1,
  57     QUERY_NETWORK = 1 << 2,
  58     // TODO(noamsml): Add flag for flushing cache when feature is implemented
  59     // Mask of all possible flags on MDnsTransaction.
  60     FLAG_MASK = (1 << 3) - 1,
  61   };
  62
  63   typedef base::Callback<void(Result, const RecordParsed*)>
  64   ResultCallback;
  65
  66   // Destroying the transaction cancels it.
  67   virtual ~MDnsTransaction() {}
  68
  69   // Start the transaction. Return true on success. Cache-based transactions
  70   // will execute the callback synchronously.
  71   virtual bool Start() = 0;
  72
  73   // Get the host or service name for the transaction.
  74   virtual const std::string& GetName() const = 0;
  75
  76   // Get the type for this transaction (SRV, TXT, A, AAA, etc)
  77   virtual uint16 GetType() const = 0;
  78 };
  79
  80 // A listener listens for updates regarding a specific record or set of records.
  81 // Created by the MDnsClient (see |MDnsClient::CreateListener|) and used to keep
  82 // track of listeners.
  83 class NET_EXPORT MDnsListener {
  84  public:
  85   // Used in the MDnsListener delegate to signify what type of change has been
  86   // made to a record.
  87   enum UpdateType {
  88     RECORD_ADDED,
  89     RECORD_CHANGED,
  90     RECORD_REMOVED
  91   };
  92
  93   class Delegate {
  94    public:
  95     virtual ~Delegate() {}
  96
  97     // Called when a record is added, removed or updated.
  98     virtual void OnRecordUpdate(UpdateType update,
  99                                 const RecordParsed* record) = 0;
 100
 101     // Called when a record is marked nonexistent by an NSEC record.
 102     virtual void OnNsecRecord(const std::string& name, unsigned type) = 0;
 103
 104     // Called when the cache is purged (due, for example, ot the network
 105     // disconnecting).
 106     virtual void OnCachePurged() = 0;
 107   };
 108
 109   // Destroying the listener stops listening.
 110   virtual ~MDnsListener() {}
 111
 112   // Start the listener. Return true on success.
 113   virtual bool Start() = 0;
 114
 115   // Get the host or service name for this query.
 116   // Return an empty string for no name.
 117   virtual const std::string& GetName() const = 0;
 118
 119   // Get the type for this query (SRV, TXT, A, AAA, etc)
 120   virtual uint16 GetType() const = 0;
 121 };
 122
 123 // Listens for Multicast DNS on the local network. You can access information
 124 // regarding multicast DNS either by creating an |MDnsListener| to be notified
 125 // of new records, or by creating an |MDnsTransaction| to look up the value of a
 126 // specific records. When all listeners and active transactions are destroyed,
 127 // the client stops listening on the network and destroys the cache.
 128 class NET_EXPORT MDnsClient {
 129  public:
 130   virtual ~MDnsClient() {}
 131
 132   // Create listener object for RRType |rrtype| and name |name|.
 133   virtual scoped_ptr<MDnsListener> CreateListener(
 134       uint16 rrtype,
 135       const std::string& name,
 136       MDnsListener::Delegate* delegate) = 0;
 137
 138   // Create a transaction that can be used to query either the MDns cache, the
 139   // network, or both for records of type |rrtype| and name |name|. |flags| is
 140   // defined by MDnsTransactionFlags.
 141   virtual scoped_ptr<MDnsTransaction> CreateTransaction(
 142       uint16 rrtype,
 143       const std::string& name,
 144       int flags,
 145       const MDnsTransaction::ResultCallback& callback) = 0;
 146
 147   virtual bool StartListening() = 0;
 148
 149   // Do not call this inside callbacks from related MDnsListener and
 150   // MDnsTransaction objects.
 151   virtual void StopListening() = 0;
 152   virtual bool IsListening() const = 0;
 153
 154   // Create the default MDnsClient
 155   static scoped_ptr<MDnsClient> CreateDefault();
 156 };
 157
 158 IPEndPoint NET_EXPORT GetMDnsIPEndPoint(AddressFamily address_family);
 159
 160 }  // namespace net
 161 #endif  // NET_DNS_MDNS_CLIENT_H_