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      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
    226