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       is_session_requested_(false),
  56       midi_manager_(midi_manager),
  57       sent_bytes_in_flight_(0),
  58       bytes_sent_since_last_acknowledgement_(0) {
  59   CHECK(midi_manager_);
  60 }
  61
  62 MidiHost::~MidiHost() {
  63   // Close an open session, or abort opening a session.
  64   if (is_session_requested_)
  65     midi_manager_->EndSession(this);
  66 }
  67
  68 void MidiHost::OnDestruct() const {
  69   BrowserThread::DeleteOnIOThread::Destruct(this);
  70 }
  71
  72 // IPC Messages handler
  73 bool MidiHost::OnMessageReceived(const IPC::Message& message) {
  74   bool handled = true;
  75   IPC_BEGIN_MESSAGE_MAP(MidiHost, message)
  76     IPC_MESSAGE_HANDLER(MidiHostMsg_StartSession, OnStartSession)
  77     IPC_MESSAGE_HANDLER(MidiHostMsg_SendData, OnSendData)
  78     IPC_MESSAGE_HANDLER(MidiHostMsg_EndSession, OnEndSession)
  79     IPC_MESSAGE_UNHANDLED(handled = false)
  80   IPC_END_MESSAGE_MAP()
  81
  82   return handled;
  83 }
  84
  85 void MidiHost::OnStartSession() {
  86   is_session_requested_ = true;
  87   midi_manager_->StartSession(this);
  88 }
  89
  90 void MidiHost::OnSendData(uint32 port,
  91                           const std::vector<uint8>& data,
  92                           double timestamp) {
  93   if (data.empty())
  94     return;
  95
  96   // Blink running in a renderer checks permission to raise a SecurityError
  97   // in JavaScript. The actual permission check for security purposes
  98   // happens here in the browser process.
  99   if (!has_sys_ex_permission_ &&
 100       std::find(data.begin(), data.end(), kSysExByte) != data.end()) {
 101     RecordAction(base::UserMetricsAction("BadMessageTerminate_MIDI"));
 102     BadMessageReceived();
 103     return;
 104   }
 105
 106   if (!IsValidWebMIDIData(data))
 107     return;
 108
 109   {
 110     base::AutoLock auto_lock(in_flight_lock_);
 111     // Sanity check that we won't send too much data.
 112     // TODO(yukawa): Consider to send an error event back to the renderer
 113     // after some future discussion in W3C.
 114     if (data.size() + sent_bytes_in_flight_ > kMaxInFlightBytes)
 115       return;
 116     sent_bytes_in_flight_ += data.size();
 117   }
 118   midi_manager_->DispatchSendMidiData(this, port, data, timestamp);
 119 }
 120
 121 void MidiHost::OnEndSession() {
 122   is_session_requested_ = false;
 123   midi_manager_->EndSession(this);
 124 }
 125
 126 void MidiHost::CompleteStartSession(media::MidiResult result) {
 127   DCHECK(is_session_requested_);
 128   MidiPortInfoList input_ports;
 129   MidiPortInfoList output_ports;
 130
 131   if (result == media::MIDI_OK) {
 132     input_ports = midi_manager_->input_ports();
 133     output_ports = midi_manager_->output_ports();
 134     received_messages_queues_.clear();
 135     received_messages_queues_.resize(input_ports.size());
 136     // ChildSecurityPolicy is set just before OnStartSession by
 137     // MidiDispatcherHost. So we can safely cache the policy.
 138     has_sys_ex_permission_ = ChildProcessSecurityPolicyImpl::GetInstance()->
 139         CanSendMidiSysExMessage(renderer_process_id_);
 140   }
 141
 142   Send(new MidiMsg_SessionStarted(result,
 143                                   input_ports,
 144                                   output_ports));
 145 }
 146
 147 void MidiHost::ReceiveMidiData(
 148     uint32 port,
 149     const uint8* data,
 150     size_t length,
 151     double timestamp) {
 152   TRACE_EVENT0("midi", "MidiHost::ReceiveMidiData");
 153
 154   if (received_messages_queues_.size() <= port)
 155     return;
 156
 157   // Lazy initialization
 158   if (received_messages_queues_[port] == NULL)
 159     received_messages_queues_[port] = new media::MidiMessageQueue(true);
 160
 161   received_messages_queues_[port]->Add(data, length);
 162   std::vector<uint8> message;
 163   while (true) {
 164     received_messages_queues_[port]->Get(&message);
 165     if (message.empty())
 166       break;
 167
 168     // MIDI devices may send a system exclusive messages even if the renderer
 169     // doesn't have a permission to receive it. Don't kill the renderer as
 170     // OnSendData() does.
 171     if (message[0] == kSysExByte && !has_sys_ex_permission_)
 172       continue;
 173
 174     // Send to the renderer.
 175     Send(new MidiMsg_DataReceived(port, message, timestamp));
 176   }
 177 }
 178
 179 void MidiHost::AccumulateMidiBytesSent(size_t n) {
 180   {
 181     base::AutoLock auto_lock(in_flight_lock_);
 182     if (n <= sent_bytes_in_flight_)
 183       sent_bytes_in_flight_ -= n;
 184   }
 185
 186   if (bytes_sent_since_last_acknowledgement_ + n >=
 187       bytes_sent_since_last_acknowledgement_)
 188     bytes_sent_since_last_acknowledgement_ += n;
 189
 190   if (bytes_sent_since_last_acknowledgement_ >=
 191       kAcknowledgementThresholdBytes) {
 192     Send(new MidiMsg_AcknowledgeSentData(
 193         bytes_sent_since_last_acknowledgement_));
 194     bytes_sent_since_last_acknowledgement_ = 0;
 195   }
 196 }
 197
 198 // static
 199 bool MidiHost::IsValidWebMIDIData(const std::vector<uint8>& data) {
 200   bool in_sysex = false;
 201   size_t waiting_data_length = 0;
 202   for (size_t i = 0; i < data.size(); ++i) {
 203     const uint8 current = data[i];
 204     if (IsSystemRealTimeMessage(current))
 205       continue;  // Real time message can be placed at any point.
 206     if (waiting_data_length > 0) {
 207       if (!IsDataByte(current))
 208         return false;  // Error: |current| should have been data byte.
 209       --waiting_data_length;
 210       continue;  // Found data byte as expected.
 211     }
 212     if (in_sysex) {
 213       if (data[i] == kEndOfSysExByte)
 214         in_sysex = false;
 215       else if (!IsDataByte(current))
 216         return false;  // Error: |current| should have been data byte.
 217       continue;  // Found data byte as expected.
 218     }
 219     if (current == kSysExByte) {
 220       in_sysex = true;
 221       continue;  // Found SysEX
 222     }
 223     waiting_data_length = media::GetMidiMessageLength(current);
 224     if (waiting_data_length == 0)
 225       return false;  // Error: |current| should have been a valid status byte.
 226     --waiting_data_length;  // Found status byte
 227   }
 228   return waiting_data_length == 0 && !in_sysex;
 229 }
 230
 231 }  // namespace content