Multicast DNS implementation (initial)

net/dns/mdns_client_impl.h

+// Copyright (c) 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.
+
+#ifndef NET_DNS_MDNS_CLIENT_IMPL_H_
+#define NET_DNS_MDNS_CLIENT_IMPL_H_
+
+#include <map>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/cancelable_callback.h"
+#include "base/observer_list.h"
+#include "net/base/io_buffer.h"
+#include "net/base/ip_endpoint.h"
+#include "net/dns/mdns_cache.h"
+#include "net/dns/mdns_client.h"
+#include "net/udp/datagram_server_socket.h"
+#include "net/udp/udp_server_socket.h"
+#include "net/udp/udp_socket.h"
+
+
+namespace net {
+
+class MDnsListenerImpl;
+
+// A connection to the network for multicast DNS clients. It reads data into
+// DnsResponse objects and alerts the delegate that a packet has been received.
+class MDnsConnection {
+ public:
+  class Delegate {
+   public:
+    // Handle an mDNS packet buffered in |response| with a size of |bytes_read|.
+    virtual void HandlePacket(DnsResponse* response, int bytes_read) = 0;
+    virtual void OnConnectionError(int error) = 0;
+    virtual ~Delegate() {}
+  };
+
+  // Start the connection. Will begin alerting the delegate of packets.
+  // Returns a net error code.
+  virtual int Init() = 0;
+
+  // Send a packet on both ipv4 and ipv6. Returns a net error code.
+  virtual int Send(IOBuffer* buffer, unsigned size) = 0;
+  virtual ~MDnsConnection() {}
+};
+
+class MDnsConnectionFactory {
+ public:
+  virtual scoped_ptr<MDnsConnection> CreateConnection(
+      MDnsConnection::Delegate* delegate) = 0;
+
+  virtual ~MDnsConnectionFactory() {}
+};
+
+class MDnsClientImpl : public MDnsClient {
+ public:
+  // The core object exists while the MDnsClient is listening for MDnsPackets,
+  // and is deleted whenever the number of references for listening reachers

[szym, 2013/06/10 21:58:29]

nit: "reaches"

Suggest: "whenever the number of listeners reaches zero."

[Noam Samuel, 2013/06/11 20:35:03]

Done.

+  // zero. The message loop may hold weak pointers to it in order to ensure
+  // tasks scheduled on it are not delivered after it is destroyed.

[szym, 2013/06/10 21:58:29]

The last sentence does not seem to be adding much.

[Noam Samuel, 2013/06/11 20:35:03]

Done.

+  class Core : public base::SupportsWeakPtr<Core>, MDnsConnection::Delegate {
+   public:
+    Core(MDnsClientImpl* client,
+         MDnsConnectionFactory* connection_factory);
+    virtual ~Core();
+
+    // Initialize the core. Returns true on success.
+    bool Init();
+
+    // Send a query with a specific rrtype and name. Returns true on success.
+    bool SendQuery(uint16 rrtype, std::string name);
+
+    // Add/remove a listener to the list of listener. May cause network traffic
+    // if listener is active.
+    void AddListener(MDnsListenerImpl* listener);
+    void RemoveListener(MDnsListenerImpl* listener);
+
+    // Query the cache for records of a specific type and name.
+    void QueryCache(uint16 rrtype, const std::string& name,
+                    std::vector<const RecordParsed*>* records) const;
+
+    // Parse the response and alert relevant listeners.
+    virtual void HandlePacket(DnsResponse* response, int bytes_read) OVERRIDE;
+
+    virtual void OnConnectionError(int error) OVERRIDE;
+
+   private:
+    typedef std::pair<uint16, std::string> ListenerKey;
+    typedef std::map<ListenerKey, ObserverList<MDnsListenerImpl>* >
+    ListenerMap;
+
+    // Alert listeners of an update to the cache.
+    void AlertListeners(MDnsUpdateType update_type,
+                        const ListenerKey& key, const RecordParsed* record);
+
+    // Schedule a cleanup to a specific time, cancelling other cleanups.
+    void ScheduleCleanup(base::Time cleanup);
+
+    // Clean up the cache and schedule a new cleanup.
+    void DoCleanup();
+
+    // Callback for when a record is removed from the cache.
+    void OnRecordRemoved(const RecordParsed* record);
+
+    ListenerMap listeners_;
+
+    MDnsClientImpl* client_;
+    MDnsCache cache_;
+
+    base::CancelableCallback<void()> cleanup_callback_;
+    base::Time scheduled_cleanup_;
+
+    scoped_ptr<MDnsConnection> connection_;
+
+    DISALLOW_COPY_AND_ASSIGN(Core);
+  };
+
+  MDnsClientImpl();
+
+  // Used only for testing. Lets users of this class decouple it from time
+  // dependence and network dependence.
+  explicit MDnsClientImpl(MDnsConnectionFactory* connection_factory);

[szym, 2013/06/10 21:58:29]

I suggest always passing the factory into the constructor. MDnsClientImpl is not
the public interface. Pass the real factory when you construct it in
MDnsClient::GetInstance.

[Noam Samuel, 2013/06/11 20:35:03]

Done.

+  virtual ~MDnsClientImpl();
+
+  // MDnsClient implementation:
+  virtual scoped_ptr<MDnsListener> CreateListener(
+      uint16 rrtype,
+      const std::string& name,
+      MDnsListener::Delegate* delegate) OVERRIDE;
+
+  virtual scoped_ptr<MDnsTransaction> CreateTransaction(
+      uint16 rrtype,
+      const std::string& name,
+      int flags,
+      const MDnsTransaction::ResultCallback& callback) OVERRIDE;
+
+
+  // Functions for testing only.
+  bool IsListeningForTests();
+
+  bool AddListenRef();
+  void SubtractListenRef();
+
+  Core* core() { return core_.get(); }
+
+ private:
+  void Shutdown();
+
+  scoped_ptr<Core> core_;
+  int listen_refs_;
+
+  // Since we can either own or not own the connection_factory, use a scoped_ptr
+  // and a ptr.
+  scoped_ptr<MDnsConnectionFactory> connection_factory_owned_;
+  MDnsConnectionFactory* connection_factory_;

[szym, 2013/06/10 21:58:29]

I suggest it should always own it. Whenever a situation like this arises, just
keep a plain (unsafe) pointer in the test fixture.

[Noam Samuel, 2013/06/11 20:35:03]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(MDnsClientImpl);
+};
+
+class MDnsListenerImpl : public MDnsListener,
+                         public base::SupportsWeakPtr<MDnsListenerImpl> {
+ public:
+  MDnsListenerImpl(uint16 rrtype,
+                   const std::string& name,
+                   MDnsListener::Delegate* delegate,
+                   MDnsClientImpl* client);
+
+  virtual ~MDnsListenerImpl();
+
+  // MDnsListener implementation:
+  virtual bool Start() OVERRIDE;
+
+  virtual const std::string& GetName() const OVERRIDE;
+
+  virtual uint16 GetType() const OVERRIDE;
+
+  MDnsListener::Delegate* delegate() { return delegate_; }
+
+  // Alert the delegate of a record update.
+  void AlertDelegate(MDnsUpdateType update_type,
+                     const RecordParsed* record_parsed);
+ private:
+  uint16 rrtype_;
+  std::string name_;
+  MDnsClientImpl* client_;
+  MDnsListener::Delegate* delegate_;
+
+  bool started_;
+  DISALLOW_COPY_AND_ASSIGN(MDnsListenerImpl);
+};
+
+class MDnsTransactionImpl : public base::SupportsWeakPtr<MDnsTransactionImpl>,
+                            public MDnsTransaction,
+                            public MDnsListener::Delegate {
+ public:
+  MDnsTransactionImpl(uint16 rrtype,
+                      const std::string& name,
+                      int flags,
+                      const MDnsTransaction::ResultCallback& callback,
+                      MDnsClientImpl* client);
+  virtual ~MDnsTransactionImpl();
+
+  // MDnsTransaction implementation:
+  virtual bool Start() OVERRIDE;
+
+  virtual const std::string& GetName() const OVERRIDE;
+  virtual uint16 GetType() const OVERRIDE;
+
+  // MDnsListener::Delegate implementation:
+  virtual void OnRecordUpdate(MDnsUpdateType update,
+                              const RecordParsed* record) OVERRIDE;
+  virtual void OnNsecRecord(const std::string& name, unsigned type) OVERRIDE;
+
+  virtual void OnCachePurged() OVERRIDE;
+
+  bool is_active() { return !callback_.is_null(); }
+
+  void Reset();
+
+ private:
+  // Trigger the callback and reset all related variables.
+  void TriggerCallback(MDnsTransactionResult result,
+                       const RecordParsed* record);
+
+  // Internal callback for when a cache record is found.
+  void CacheRecordFound(const RecordParsed* record);
+
+  // Signal the transactionis over and release all related resources.
+  void SignalTransactionOver();
+
+  uint16 rrtype_;
+  std::string name_;
+  MDnsTransaction::ResultCallback callback_;
+
+  scoped_ptr<MDnsListener> listener_;
+  base::CancelableCallback<void()> timeout_;
+
+  MDnsClientImpl* client_;
+
+  bool started_;
+  int flags_;
+
+  DISALLOW_COPY_AND_ASSIGN(MDnsTransactionImpl);
+};
+
+// This implementation of MDnsConnection handles connecting to both IPv4 and
+// IPv6.
+class MDnsConnectionImpl : public MDnsConnection {
+ public:
+  explicit MDnsConnectionImpl(MDnsConnection::Delegate* delegate);
+  MDnsConnectionImpl(DatagramServerSocket* socket_ipv4,
+                     DatagramServerSocket* socket_ipv6,
+                     MDnsConnection::Delegate* delegate);
+
+  virtual ~MDnsConnectionImpl();
+
+  virtual int Init() OVERRIDE;
+  virtual int Send(IOBuffer* buffer, unsigned size) OVERRIDE;
+
+ private:
+  class SocketHandler {
+   public:
+    // Pass the socket in. Used for testing.
+    SocketHandler(DatagramServerSocket* socket, MDnsConnectionImpl* connection,
+             const IPEndPoint& multicast_addr);
+    SocketHandler(MDnsConnectionImpl* connection,
+                  const IPEndPoint& multicast_addr);
+    ~SocketHandler();
+    int DoLoop(int rv);
+    int Start();
+
+    int Send(IOBuffer* buffer, unsigned size);
+
+   private:
+    int BindSocket();
+    void OnDatagramReceived(int rv);
+
+    // Callback for when sending a query has finished.
+    void SendDone(int sent);
+
+    scoped_ptr<DatagramServerSocket> socket_owned_;
+    DatagramServerSocket* socket_;
+
+    MDnsConnectionImpl* connection_;
+    IPEndPoint recv_addr_;
+    scoped_ptr<DnsResponse> response_;
+    IPEndPoint multicast_addr_;
+  };
+
+  // Callback for handling a datagram being recieved on either ipv4 or ipv6.

[szym, 2013/06/10 21:58:29]

nit: "received"

[Noam Samuel, 2013/06/11 20:35:03]

Done.

+  // Responsible for ensuring we request another packet from the network.

[szym, 2013/06/10 21:58:29]

This sentence is obsolete.

[Noam Samuel, 2013/06/11 20:35:03]

Done.

+  void OnDatagramReceived(DatagramServerSocket* socket,
+                          DnsResponse* response,
+                          IPEndPoint* recv_addr,
+                          int bytes_read);
+
+  void OnError(SocketHandler* loop, int error);
+
+  IPEndPoint GetIPEndPoint(const char* address, int port);
+
+  SocketHandler socket_handler_ipv4_;
+  SocketHandler socket_handler_ipv6_;
+
+  MDnsConnection::Delegate* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(MDnsConnectionImpl);
+};
+
+class MDnsConnectionImplFactory : public MDnsConnectionFactory {
+ public:
+  MDnsConnectionImplFactory();
+  virtual ~MDnsConnectionImplFactory();
+
+  virtual scoped_ptr<MDnsConnection> CreateConnection(
+      MDnsConnection::Delegate* delegate) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MDnsConnectionImplFactory);
+};
+
+}
+#endif  // NET_DNS_MDNS_CLIENT_IMPL_H_