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 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     : 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 // IPC Messages handler
  69 bool MidiHost::OnMessageReceived(const IPC::Message& message,
  70                                  bool* message_was_ok) {
  71   bool handled = true;
  72   IPC_BEGIN_MESSAGE_MAP_EX(MidiHost, message, *message_was_ok)
  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_EX()
  77
  78   return handled;
  79 }
  80
  81 void MidiHost::OnStartSession(int client_id) {
  82   MidiPortInfoList input_ports;
  83   MidiPortInfoList output_ports;
  84
  85   // Initialize devices and register to receive MIDI data.
  86   bool success = false;
  87   if (midi_manager_) {
  88     success = midi_manager_->StartSession(this);
  89     if (success) {
  90       input_ports = midi_manager_->input_ports();
  91       output_ports = midi_manager_->output_ports();
  92       received_messages_queues_.clear();
  93       received_messages_queues_.resize(input_ports.size());
  94       // ChildSecurityPolicy is set just before OnStartSession by
  95       // MidiDispatcherHost. So we can safely cache the policy.
  96       has_sys_ex_permission_ = ChildProcessSecurityPolicyImpl::GetInstance()->
  97           CanSendMidiSysExMessage(renderer_process_id_);
  98     }
  99   }
 100
 101   Send(new MidiMsg_SessionStarted(
 102        client_id,
 103        success,
 104        input_ports,
 105        output_ports));
 106 }
 107
 108 void MidiHost::OnSendData(uint32 port,
 109                           const std::vector<uint8>& data,
 110                           double timestamp) {
 111   if (!midi_manager_)
 112     return;
 113
 114   if (data.empty())
 115     return;
 116
 117   // Blink running in a renderer checks permission to raise a SecurityError
 118   // in JavaScript. The actual permission check for security purposes
 119   // happens here in the browser process.
 120   if (!has_sys_ex_permission_ &&
 121       std::find(data.begin(), data.end(), kSysExByte) != data.end()) {
 122     RecordAction(base::UserMetricsAction("BadMessageTerminate_MIDI"));
 123     BadMessageReceived();
 124     return;
 125   }
 126
 127   if (!IsValidWebMIDIData(data))
 128     return;
 129
 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     sent_bytes_in_flight_ += data.size();
 138   }
 139   midi_manager_->DispatchSendMidiData(this, port, data, timestamp);
 140 }
 141
 142 void MidiHost::ReceiveMidiData(
 143     uint32 port,
 144     const uint8* data,
 145     size_t length,
 146     double timestamp) {
 147   TRACE_EVENT0("midi", "MidiHost::ReceiveMidiData");
 148
 149   if (received_messages_queues_.size() <= port)
 150     return;
 151
 152   // Lazy initialization
 153   if (received_messages_queues_[port] == NULL)
 154     received_messages_queues_[port] = new media::MidiMessageQueue(true);
 155
 156   received_messages_queues_[port]->Add(data, length);
 157   std::vector<uint8> message;
 158   while (true) {
 159     received_messages_queues_[port]->Get(&message);
 160     if (message.empty())
 161       break;
 162
 163     // MIDI devices may send a system exclusive messages even if the renderer
 164     // doesn't have a permission to receive it. Don't kill the renderer as
 165     // OnSendData() does.
 166     if (message[0] == kSysExByte && !has_sys_ex_permission_)
 167       continue;
 168
 169     // Send to the renderer.
 170     Send(new MidiMsg_DataReceived(port, message, timestamp));
 171   }
 172 }
 173
 174 void MidiHost::AccumulateMidiBytesSent(size_t n) {
 175   {
 176     base::AutoLock auto_lock(in_flight_lock_);
 177     if (n <= sent_bytes_in_flight_)
 178       sent_bytes_in_flight_ -= n;
 179   }
 180
 181   if (bytes_sent_since_last_acknowledgement_ + n >=
 182       bytes_sent_since_last_acknowledgement_)
 183     bytes_sent_since_last_acknowledgement_ += n;
 184
 185   if (bytes_sent_since_last_acknowledgement_ >=
 186       kAcknowledgementThresholdBytes) {
 187     Send(new MidiMsg_AcknowledgeSentData(
 188         bytes_sent_since_last_acknowledgement_));
 189     bytes_sent_since_last_acknowledgement_ = 0;
 190   }
 191 }
 192
 193 // static
 194 bool MidiHost::IsValidWebMIDIData(const std::vector<uint8>& data) {
 195   bool in_sysex = false;
 196   size_t waiting_data_length = 0;
 197   for (size_t i = 0; i < data.size(); ++i) {
 198     const uint8 current = data[i];
 199     if (IsSystemRealTimeMessage(current))
 200       continue;  // Real time message can be placed at any point.
 201     if (waiting_data_length > 0) {
 202       if (!IsDataByte(current))
 203         return false;  // Error: |current| should have been data byte.
 204       --waiting_data_length;
 205       continue;  // Found data byte as expected.
 206     }
 207     if (in_sysex) {
 208       if (data[i] == kEndOfSysExByte)
 209         in_sysex = false;
 210       else if (!IsDataByte(current))
 211         return false;  // Error: |current| should have been data byte.
 212       continue;  // Found data byte as expected.
 213     }
 214     if (current == kSysExByte) {
 215       in_sysex = true;
 216       continue;  // Found SysEX
 217     }
 218     waiting_data_length = media::GetMidiMessageLength(current);
 219     if (waiting_data_length == 0)
 220       return false;  // Error: |current| should have been a valid status byte.
 221     --waiting_data_length;  // Found status byte
 222   }
 223   return waiting_data_length == 0 && !in_sysex;
 224 }
 225
 226 }  // namespace content