chrome/nacl/nacl_ipc_adapter.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 CHROME_NACL_NACL_IPC_ADAPTER_H_
   6 #define CHROME_NACL_NACL_IPC_ADAPTER_H_
   7
   8 #include <map>
   9 #include <queue>
  10 #include <string>
  11
  12 #include "base/basictypes.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "base/memory/scoped_vector.h"
  16 #include "base/pickle.h"
  17 #include "base/shared_memory.h"
  18 #include "base/synchronization/condition_variable.h"
  19 #include "base/synchronization/lock.h"
  20 #include "base/task_runner.h"
  21 #include "ipc/ipc_listener.h"
  22
  23 struct NaClDesc;
  24 struct NaClImcTypedMsgHdr;
  25 struct PP_Size;
  26
  27 namespace IPC {
  28 class Channel;
  29 struct ChannelHandle;
  30 }
  31
  32 namespace nacl {
  33 class DescWrapper;
  34 }
  35
  36 namespace ppapi {
  37 class HostResource;
  38 }
  39
  40 // Adapts a Chrome IPC channel to an IPC channel that we expose to Native
  41 // Client. This provides a mapping in both directions, so when IPC messages
  42 // come in from another process, we rewrite them and allow them to be received
  43 // via a recvmsg-like interface in the NaCl code. When NaCl code calls sendmsg,
  44 // we implement that as sending IPC messages on the channel.
  45 //
  46 // This object also provides the necessary logic for rewriting IPC messages.
  47 // NaCl code is platform-independent and runs in a Posix-like enviroment, but
  48 // some formatting in the message and the way handles are transferred varies
  49 // by platform. This class bridges that gap to provide what looks like a
  50 // normal platform-specific IPC implementation to Chrome, and a Posix-like
  51 // version on every platform to NaCl.
  52 //
  53 // This object must be threadsafe since the nacl environment determines which
  54 // thread every function is called on.
  55 class NaClIPCAdapter : public base::RefCountedThreadSafe<NaClIPCAdapter>,
  56                        public IPC::Listener {
  57  public:
  58   // Chrome's IPC message format varies by platform, NaCl's does not. In
  59   // particular, the header has some extra fields on Posix platforms. Since
  60   // NaCl is a Posix environment, it gets that version of the header. This
  61   // header is duplicated here so we have a cross-platform definition of the
  62   // header we're exposing to NaCl.
  63 #pragma pack(push, 4)
  64   struct NaClMessageHeader : public Pickle::Header {
  65     int32 routing;
  66     uint32 type;
  67     uint32 flags;
  68     uint16 num_fds;
  69     uint16 pad;
  70   };
  71 #pragma pack(pop)
  72
  73   // Creates an adapter, using the thread associated with the given task
  74   // runner for posting messages. In normal use, the task runner will post to
  75   // the I/O thread of the process.
  76   //
  77   // If you use this constructor, you MUST call ConnectChannel after the
  78   // NaClIPCAdapter is constructed, or the NaClIPCAdapter's channel will not be
  79   // connected.
  80   NaClIPCAdapter(const IPC::ChannelHandle& handle, base::TaskRunner* runner);
  81
  82   // Initializes with a given channel that's already created for testing
  83   // purposes. This function will take ownership of the given channel.
  84   NaClIPCAdapter(scoped_ptr<IPC::Channel> channel, base::TaskRunner* runner);
  85
  86   // Connect the channel. This must be called after the constructor that accepts
  87   // an IPC::ChannelHandle, and causes the Channel to be connected on the IO
  88   // thread.
  89   void ConnectChannel();
  90
  91   // Implementation of sendmsg. Returns the number of bytes written or -1 on
  92   // failure.
  93   int Send(const NaClImcTypedMsgHdr* msg);
  94
  95   // Implementation of recvmsg. Returns the number of bytes read or -1 on
  96   // failure. This will block until there's an error or there is data to
  97   // read.
  98   int BlockingReceive(NaClImcTypedMsgHdr* msg);
  99
 100   // Closes the IPC channel.
 101   void CloseChannel();
 102
 103   // Make a NaClDesc that refers to this NaClIPCAdapter. Note that the returned
 104   // NaClDesc is reference-counted, and a reference is returned.
 105   NaClDesc* MakeNaClDesc();
 106
 107 #if defined(OS_POSIX)
 108   int TakeClientFileDescriptor();
 109 #endif
 110
 111   // Listener implementation.
 112   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 113   virtual void OnChannelConnected(int32 peer_pid) OVERRIDE;
 114   virtual void OnChannelError() OVERRIDE;
 115
 116  private:
 117   friend class base::RefCountedThreadSafe<NaClIPCAdapter>;
 118
 119   class RewrittenMessage;
 120
 121   // This is the data that must only be accessed inside the lock. This struct
 122   // just separates it so it's easier to see.
 123   struct LockedData {
 124     LockedData();
 125     ~LockedData();
 126
 127     // Messages that we have read off of the Chrome IPC channel that are waiting
 128     // to be received by the plugin.
 129     std::queue< scoped_refptr<RewrittenMessage> > to_be_received_;
 130
 131     // When we send a synchronous message (from untrusted to trusted), we store
 132     // its type here, so that later we can associate the reply with its type
 133     // and potentially translate handles in the message.
 134     typedef std::map<int, uint32> PendingSyncMsgMap;
 135     PendingSyncMsgMap pending_sync_msgs_;
 136
 137     // Data that we've queued from the plugin to send, but doesn't consist of a
 138     // full message yet. The calling code can break apart the message into
 139     // smaller pieces, and we need to send the message to the other process in
 140     // one chunk.
 141     //
 142     // The IPC channel always starts a new send() at the beginning of each
 143     // message, so we don't need to worry about arbitrary message boundaries.
 144     std::string to_be_sent_;
 145
 146     bool channel_closed_;
 147   };
 148
 149   // This is the data that must only be accessed on the I/O thread (as defined
 150   // by TaskRunner). This struct just separates it so it's easier to see.
 151   struct IOThreadData {
 152     IOThreadData();
 153     ~IOThreadData();
 154
 155     scoped_ptr<IPC::Channel> channel_;
 156   };
 157
 158   virtual ~NaClIPCAdapter();
 159
 160   // Returns 0 if nothing is waiting.
 161   int LockedReceive(NaClImcTypedMsgHdr* msg);
 162
 163   // Sends a message that we know has been completed to the Chrome process.
 164   bool SendCompleteMessage(const char* buffer, size_t buffer_len);
 165
 166   // Clears the LockedData.to_be_sent_ structure in a way to make sure that
 167   // the memory is deleted. std::string can sometimes hold onto the buffer
 168   // for future use which we don't want.
 169   void ClearToBeSent();
 170
 171   void ConnectChannelOnIOThread();
 172   void CloseChannelOnIOThread();
 173   void SendMessageOnIOThread(scoped_ptr<IPC::Message> message);
 174
 175   // Saves the message to forward to NaCl. This method assumes that the caller
 176   // holds the lock for locked_data_.
 177   void SaveMessage(const IPC::Message& message,
 178                    RewrittenMessage* rewritten_message);
 179
 180   base::Lock lock_;
 181   base::ConditionVariable cond_var_;
 182
 183   scoped_refptr<base::TaskRunner> task_runner_;
 184
 185   // To be accessed inside of lock_ only.
 186   LockedData locked_data_;
 187
 188   // To be accessed on the I/O thread (via task runner) only.
 189   IOThreadData io_thread_data_;
 190
 191   DISALLOW_COPY_AND_ASSIGN(NaClIPCAdapter);
 192 };
 193
 194 #endif  // CHROME_NACL_NACL_IPC_ADAPTER_H_