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// Copyright 2013 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.
#include <string>
#include <vector>
#include "base/callback.h"
#include "net/base/ip_endpoint.h"
#include "net/dns/dns_query.h"
#include "net/dns/dns_response.h"
#include "net/dns/record_parsed.h"
namespace net {
class DatagramServerSocket;
class RecordParsed;
// Represents a one-time record lookup. A transaction takes one
// associated callback (see |MDnsClient::CreateTransaction|) and calls it
// whenever a matching record has been found, either from the cache or
// by querying the network (it may choose to query either or both based on its
// creation flags, see MDnsTransactionFlags). Network-based transactions will
// time out after a reasonable number of seconds.
class NET_EXPORT MDnsTransaction {
// Used to signify what type of result the transaction has received.
enum Result {
// Passed whenever a record is found.
// The transaction is done. Applies to non-single-valued transactions. Is
// called when the transaction has finished (this is the last call to the
// callback).
// No results have been found. Applies to single-valued transactions. Is
// called when the transaction has finished without finding any results.
// For transactions that use the network, this happens when a timeout
// occurs, for transactions that are cache-only, this happens when no
// results are in the cache.
// Called when an NSec record is read for this transaction's
// query. This means there cannot possibly be a record of the type
// and name for this transaction.
// Used when creating an MDnsTransaction.
enum Flags {
// Transaction should return only one result, and stop listening after it.
// Note that single result transactions will signal when their timeout is
// reached, whereas multi-result transactions will not.
// Query the cache or the network. May both be used. One must be present.
QUERY_CACHE = 1 << 1,
// TODO(noamsml): Add flag for flushing cache when feature is implemented
// Mask of all possible flags on MDnsTransaction.
FLAG_MASK = (1 << 3) - 1,
typedef base::Callback<void(Result, const RecordParsed*)>
// Destroying the transaction cancels it.
virtual ~MDnsTransaction() {}
// Start the transaction. Return true on success. Cache-based transactions
// will execute the callback synchronously.
virtual bool Start() = 0;
// Get the host or service name for the transaction.
virtual const std::string& GetName() const = 0;
// Get the type for this transaction (SRV, TXT, A, AAA, etc)
virtual uint16 GetType() const = 0;
// A listener listens for updates regarding a specific record or set of records.
// Created by the MDnsClient (see |MDnsClient::CreateListener|) and used to keep
// track of listeners.
class NET_EXPORT MDnsListener {
// Used in the MDnsListener delegate to signify what type of change has been
// made to a record.
enum UpdateType {
class Delegate {
virtual ~Delegate() {}
// Called when a record is added, removed or updated.
virtual void OnRecordUpdate(UpdateType update,
const RecordParsed* record) = 0;
// Called when a record is marked nonexistent by an NSEC record.
virtual void OnNsecRecord(const std::string& name, unsigned type) = 0;
// Called when the cache is purged (due, for example, ot the network
// disconnecting).
virtual void OnCachePurged() = 0;
// Destroying the listener stops listening.
virtual ~MDnsListener() {}
// Start the listener. Return true on success.
virtual bool Start() = 0;
// Actively refresh any received records.
virtual void SetActiveRefresh(bool active_refresh) = 0;
// Get the host or service name for this query.
// Return an empty string for no name.
virtual const std::string& GetName() const = 0;
// Get the type for this query (SRV, TXT, A, AAA, etc)
virtual uint16 GetType() const = 0;
// Creates bound datagram sockets ready to use by MDnsClient.
class NET_EXPORT MDnsSocketFactory {
virtual ~MDnsSocketFactory() {}
virtual void CreateSockets(ScopedVector<DatagramServerSocket>* sockets) = 0;
static scoped_ptr<MDnsSocketFactory> CreateDefault();
// Listens for Multicast DNS on the local network. You can access information
// regarding multicast DNS either by creating an |MDnsListener| to be notified
// of new records, or by creating an |MDnsTransaction| to look up the value of a
// specific records. When all listeners and active transactions are destroyed,
// the client stops listening on the network and destroys the cache.
class NET_EXPORT MDnsClient {
virtual ~MDnsClient() {}
// Create listener object for RRType |rrtype| and name |name|.
virtual scoped_ptr<MDnsListener> CreateListener(
uint16 rrtype,
const std::string& name,
MDnsListener::Delegate* delegate) = 0;
// Create a transaction that can be used to query either the MDns cache, the
// network, or both for records of type |rrtype| and name |name|. |flags| is
// defined by MDnsTransactionFlags.
virtual scoped_ptr<MDnsTransaction> CreateTransaction(
uint16 rrtype,
const std::string& name,
int flags,
const MDnsTransaction::ResultCallback& callback) = 0;
virtual bool StartListening(MDnsSocketFactory* factory) = 0;
// Do not call this inside callbacks from related MDnsListener and
// MDnsTransaction objects.
virtual void StopListening() = 0;
virtual bool IsListening() const = 0;
// Create the default MDnsClient
static scoped_ptr<MDnsClient> CreateDefault();
NET_EXPORT IPEndPoint GetMDnsIPEndPoint(AddressFamily address_family);
typedef std::vector<std::pair<uint32, AddressFamily> > InterfaceIndexFamilyList;
// Returns pairs of interface and address family to bind. Current
// implementation returns unique list of all available interfaces.
NET_EXPORT InterfaceIndexFamilyList GetMDnsInterfacesToBind();
// Create sockets, binds socket to MDns endpoint, and sets multicast interface
// and joins multicast group on for |interface_index|.
// Returns NULL if failed.
NET_EXPORT scoped_ptr<DatagramServerSocket> CreateAndBindMDnsSocket(
AddressFamily address_family,
uint32 interface_index);
} // namespace net