content/browser/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/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 bool IsDataByte(uint8 data) {
  39   return (data & 0x80) == 0;
  40 }
  41
  42 bool IsSystemRealTimeMessage(uint8 data) {
  43   return 0xf8 <= data && data <= 0xff;
  44 }
  45
  46 }  // namespace
  47
  48 using media::kSysExByte;
  49 using media::kEndOfSysExByte;
  50
  51 MidiHost::MidiHost(int renderer_process_id, media::MidiManager* midi_manager)
  52     : BrowserMessageFilter(MidiMsgStart),
  53       renderer_process_id_(renderer_process_id),
  54       has_sys_ex_permission_(false),
  55       midi_manager_(midi_manager),
  56       sent_bytes_in_flight_(0),
  57       bytes_sent_since_last_acknowledgement_(0) {
  58 }
  59
  60 MidiHost::~MidiHost() {
  61   if (midi_manager_)
  62     midi_manager_->EndSession(this);
  63 }
  64
  65 void MidiHost::OnDestruct() const {
  66   BrowserThread::DeleteOnIOThread::Destruct(this);
  67 }
  68
  69 // IPC Messages handler
  70 bool MidiHost::OnMessageReceived(const IPC::Message& message) {
  71   bool handled = true;
  72   IPC_BEGIN_MESSAGE_MAP(MidiHost, message)
  73     IPC_MESSAGE_HANDLER(MidiHostMsg_StartSession, OnStartSession)
  74     IPC_MESSAGE_HANDLER(MidiHostMsg_SendData, OnSendData)
  75     IPC_MESSAGE_UNHANDLED(handled = false)
  76   IPC_END_MESSAGE_MAP()
  77
  78   return handled;
  79 }
  80
  81 void MidiHost::OnStartSession(int client_id) {
  82   if (midi_manager_)
  83     midi_manager_->StartSession(this, client_id);
  84 }
  85
  86 void MidiHost::OnSendData(uint32 port,
  87                           const std::vector<uint8>& data,
  88                           double timestamp) {
  89   if (!midi_manager_)
  90     return;
  91
  92   if (data.empty())
  93     return;
  94
  95   // Blink running in a renderer checks permission to raise a SecurityError
  96   // in JavaScript. The actual permission check for security purposes
  97   // happens here in the browser process.
  98   if (!has_sys_ex_permission_ &&
  99       std::find(data.begin(), data.end(), kSysExByte) != data.end()) {
 100     RecordAction(base::UserMetricsAction("BadMessageTerminate_MIDI"));
 101     BadMessageReceived();
 102     return;
 103   }
 104
 105   if (!IsValidWebMIDIData(data))
 106     return;
 107
 108   {
 109     base::AutoLock auto_lock(in_flight_lock_);
 110     // Sanity check that we won't send too much data.
 111     // TODO(yukawa): Consider to send an error event back to the renderer
 112     // after some future discussion in W3C.
 113     if (data.size() + sent_bytes_in_flight_ > kMaxInFlightBytes)
 114       return;
 115     sent_bytes_in_flight_ += data.size();
 116   }
 117   midi_manager_->DispatchSendMidiData(this, port, data, timestamp);
 118 }
 119
 120 void MidiHost::CompleteStartSession(int client_id, media::MidiResult result) {
 121   MidiPortInfoList input_ports;
 122   MidiPortInfoList output_ports;
 123
 124   if (result == media::MIDI_OK) {
 125     input_ports = midi_manager_->input_ports();
 126     output_ports = midi_manager_->output_ports();
 127     received_messages_queues_.clear();
 128     received_messages_queues_.resize(input_ports.size());
 129     // ChildSecurityPolicy is set just before OnStartSession by
 130     // MidiDispatcherHost. So we can safely cache the policy.
 131     has_sys_ex_permission_ = ChildProcessSecurityPolicyImpl::GetInstance()->
 132         CanSendMidiSysExMessage(renderer_process_id_);
 133   }
 134
 135   Send(new MidiMsg_SessionStarted(client_id,
 136                                   result,
 137                                   input_ports,
 138                                   output_ports));
 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] == kSysExByte && !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] == kEndOfSysExByte)
 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 == kSysExByte) {
 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