content/browser/renderer_host/media/midi_host.cc

   1 // Copyright (c) 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 #include "content/browser/renderer_host/media/midi_host.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/debug/trace_event.h"
  10 #include "base/process/process.h"
  11 #include "content/browser/browser_main_loop.h"
  12 #include "content/browser/child_process_security_policy_impl.h"
  13 #include "content/browser/media/media_internals.h"
  14 #include "content/common/media/midi_messages.h"
  15 #include "content/public/browser/content_browser_client.h"
  16 #include "content/public/browser/media_observer.h"
  17 #include "content/public/browser/user_metrics.h"
  18 #include "media/midi/midi_manager.h"
  19 #include "media/midi/midi_message_queue.h"
  20 #include "media/midi/midi_message_util.h"
  21
  22 using media::MIDIManager;
  23 using media::MIDIPortInfoList;
  24
  25 namespace content {
  26 namespace {
  27
  28 // The total number of bytes which we're allowed to send to the OS
  29 // before knowing that they have been successfully sent.
  30 const size_t kMaxInFlightBytes = 10 * 1024 * 1024;  // 10 MB.
  31
  32 // We keep track of the number of bytes successfully sent to
  33 // the hardware.  Every once in a while we report back to the renderer
  34 // the number of bytes sent since the last report. This threshold determines
  35 // how many bytes will be sent before reporting back to the renderer.
  36 const size_t kAcknowledgementThresholdBytes = 1024 * 1024;  // 1 MB.
  37
  38 const uint8 kSysExMessage = 0xf0;
  39 const uint8 kEndOfSysExMessage = 0xf7;
  40
  41 bool IsDataByte(uint8 data) {
  42   return (data & 0x80) == 0;
  43 }
  44
  45 bool IsSystemRealTimeMessage(uint8 data) {
  46   return 0xf8 <= data && data <= 0xff;
  47 }
  48
  49 }  // namespace
  50
  51 MIDIHost::MIDIHost(int renderer_process_id, media::MIDIManager* midi_manager)
  52     : renderer_process_id_(renderer_process_id),
  53       has_sys_ex_permission_(false),
  54       midi_manager_(midi_manager),
  55       sent_bytes_in_flight_(0),
  56       bytes_sent_since_last_acknowledgement_(0) {
  57 }
  58
  59 MIDIHost::~MIDIHost() {
  60   if (midi_manager_)
  61     midi_manager_->EndSession(this);
  62 }
  63
  64 void MIDIHost::OnDestruct() const {
  65   BrowserThread::DeleteOnIOThread::Destruct(this);
  66 }
  67
  68 ///////////////////////////////////////////////////////////////////////////////
  69 // IPC Messages handler
  70 bool MIDIHost::OnMessageReceived(const IPC::Message& message,
  71                                  bool* message_was_ok) {
  72   bool handled = true;
  73   IPC_BEGIN_MESSAGE_MAP_EX(MIDIHost, message, *message_was_ok)
  74     IPC_MESSAGE_HANDLER(MIDIHostMsg_StartSession, OnStartSession)
  75     IPC_MESSAGE_HANDLER(MIDIHostMsg_SendData, OnSendData)
  76     IPC_MESSAGE_UNHANDLED(handled = false)
  77   IPC_END_MESSAGE_MAP_EX()
  78
  79   return handled;
  80 }
  81
  82 void MIDIHost::OnStartSession(int client_id) {
  83   MIDIPortInfoList input_ports;
  84   MIDIPortInfoList output_ports;
  85
  86   // Initialize devices and register to receive MIDI data.
  87   bool success = false;
  88   if (midi_manager_) {
  89     success = midi_manager_->StartSession(this);
  90     if (success) {
  91       input_ports = midi_manager_->input_ports();
  92       output_ports = midi_manager_->output_ports();
  93       received_messages_queues_.clear();
  94       received_messages_queues_.resize(input_ports.size());
  95       // ChildSecurityPolicy is set just before OnStartSession by
  96       // MIDIDispatcherHost. So we can safely cache the policy.
  97       has_sys_ex_permission_ = ChildProcessSecurityPolicyImpl::GetInstance()->
  98           CanSendMIDISysExMessage(renderer_process_id_);
  99     }
 100   }
 101
 102   Send(new MIDIMsg_SessionStarted(
 103        client_id,
 104        success,
 105        input_ports,
 106        output_ports));
 107 }
 108
 109 void MIDIHost::OnSendData(uint32 port,
 110                           const std::vector<uint8>& data,
 111                           double timestamp) {
 112   if (!midi_manager_)
 113     return;
 114
 115   if (data.empty())
 116     return;
 117
 118   // Blink running in a renderer checks permission to raise a SecurityError
 119   // in JavaScript. The actual permission check for security purposes
 120   // happens here in the browser process.
 121   if (!has_sys_ex_permission_ &&
 122       (std::find(data.begin(), data.end(), kSysExMessage) != data.end())) {
 123     RecordAction(UserMetricsAction("BadMessageTerminate_MIDI"));
 124     BadMessageReceived();
 125     return;
 126   }
 127
 128   if (!IsValidWebMIDIData(data))
 129     return;
 130
 131   base::AutoLock auto_lock(in_flight_lock_);
 132   // Sanity check that we won't send too much data.
 133   // TODO(yukawa): Consider to send an error event back to the renderer
 134   // after some future discussion in W3C.
 135   if (data.size() + sent_bytes_in_flight_ > kMaxInFlightBytes)
 136     return;
 137   midi_manager_->DispatchSendMIDIData(this, port, data, timestamp);
 138   sent_bytes_in_flight_ += data.size();
 139 }
 140
 141 void MIDIHost::ReceiveMIDIData(
 142     uint32 port,
 143     const uint8* data,
 144     size_t length,
 145     double timestamp) {
 146   TRACE_EVENT0("midi", "MIDIHost::ReceiveMIDIData");
 147
 148   if (received_messages_queues_.size() <= port)
 149     return;
 150
 151   // Lazy initialization
 152   if (received_messages_queues_[port] == NULL)
 153     received_messages_queues_[port] = new media::MIDIMessageQueue(true);
 154
 155   received_messages_queues_[port]->Add(data, length);
 156   std::vector<uint8> message;
 157   while (true) {
 158     received_messages_queues_[port]->Get(&message);
 159     if (message.empty())
 160       break;
 161
 162     // MIDI devices may send a system exclusive messages even if the renderer
 163     // doesn't have a permission to receive it. Don't kill the renderer as
 164     // OnSendData() does.
 165     if (message[0] == kSysExMessage && !has_sys_ex_permission_)
 166       continue;
 167
 168     // Send to the renderer.
 169     Send(new MIDIMsg_DataReceived(port, message, timestamp));
 170   }
 171 }
 172
 173 void MIDIHost::AccumulateMIDIBytesSent(size_t n) {
 174   {
 175     base::AutoLock auto_lock(in_flight_lock_);
 176     if (n <= sent_bytes_in_flight_)
 177       sent_bytes_in_flight_ -= n;
 178   }
 179
 180   if (bytes_sent_since_last_acknowledgement_ + n >=
 181       bytes_sent_since_last_acknowledgement_)
 182     bytes_sent_since_last_acknowledgement_ += n;
 183
 184   if (bytes_sent_since_last_acknowledgement_ >=
 185       kAcknowledgementThresholdBytes) {
 186     Send(new MIDIMsg_AcknowledgeSentData(
 187         bytes_sent_since_last_acknowledgement_));
 188     bytes_sent_since_last_acknowledgement_ = 0;
 189   }
 190 }
 191
 192 // static
 193 bool MIDIHost::IsValidWebMIDIData(const std::vector<uint8>& data) {
 194   bool in_sysex = false;
 195   size_t waiting_data_length = 0;
 196   for (size_t i = 0; i < data.size(); ++i) {
 197     const uint8 current = data[i];
 198     if (IsSystemRealTimeMessage(current))
 199       continue;  // Real time message can be placed at any point.
 200     if (waiting_data_length > 0) {
 201       if (!IsDataByte(current))
 202         return false;  // Error: |current| should have been data byte.
 203       --waiting_data_length;
 204       continue;  // Found data byte as expected.
 205     }
 206     if (in_sysex) {
 207       if (data[i] == kEndOfSysExMessage)
 208         in_sysex = false;
 209       else if (!IsDataByte(current))
 210         return false;  // Error: |current| should have been data byte.
 211       continue;  // Found data byte as expected.
 212     }
 213     if (current == kSysExMessage) {
 214       in_sysex = true;
 215       continue;  // Found SysEX
 216     }
 217     waiting_data_length = media::GetMIDIMessageLength(current);
 218     if (waiting_data_length == 0)
 219       return false;  // Error: |current| should have been a valid status byte.
 220     --waiting_data_length;  // Found status byte
 221   }
 222   return waiting_data_length == 0 && !in_sysex;
 223 }
 224
 225 }  // namespace content