media/midi/usb_midi_descriptor_parser.cc

   1 // Copyright 2014 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 "media/midi/usb_midi_descriptor_parser.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/logging.h"
  10 #include "base/strings/stringprintf.h"
  11
  12 namespace media {
  13 namespace midi {
  14
  15 namespace {
  16
  17 // The constants below are specified in USB spec, USB audio spec
  18 // and USB midi spec.
  19
  20 enum DescriptorType {
  21   TYPE_DEVICE = 1,
  22   TYPE_CONFIGURATION = 2,
  23   TYPE_STRING = 3,
  24   TYPE_INTERFACE = 4,
  25   TYPE_ENDPOINT = 5,
  26   TYPE_DEVICE_QUALIFIER = 6,
  27   TYPE_OTHER_SPEED_CONFIGURATION = 7,
  28   TYPE_INTERFACE_POWER = 8,
  29
  30   TYPE_CS_INTERFACE = 36,
  31   TYPE_CS_ENDPOINT = 37,
  32 };
  33
  34 enum DescriptorSubType {
  35   SUBTYPE_MS_DESCRIPTOR_UNDEFINED = 0,
  36   SUBTYPE_MS_HEADER = 1,
  37   SUBTYPE_MIDI_IN_JACK = 2,
  38   SUBTYPE_MIDI_OUT_JACK = 3,
  39   SUBTYPE_ELEMENT = 4,
  40 };
  41
  42 enum JackType {
  43   JACK_TYPE_UNDEFINED = 0,
  44   JACK_TYPE_EMBEDDED = 1,
  45   JACK_TYPE_EXTERNAL = 2,
  46 };
  47
  48 const uint8 kAudioInterfaceClass = 1;
  49 const uint8 kAudioMidiInterfaceSubclass = 3;
  50
  51 class JackMatcher {
  52  public:
  53   explicit JackMatcher(uint8 id) : id_(id) {}
  54
  55   bool operator() (const UsbMidiJack& jack) const {
  56     return jack.jack_id == id_;
  57   }
  58
  59  private:
  60   uint8 id_;
  61 };
  62
  63 int DecodeBcd(uint8 byte) {
  64   DCHECK_LT((byte & 0xf0) >> 4, 0xa);
  65   DCHECK_LT(byte & 0x0f, 0xa);
  66   return ((byte & 0xf0) >> 4) * 10 + (byte & 0x0f);
  67 }
  68
  69 }  // namespace
  70
  71 std::string UsbMidiDescriptorParser::DeviceInfo::BcdVersionToString(
  72     uint16 version) {
  73   return base::StringPrintf("%d.%02d", DecodeBcd(version >> 8),
  74                             DecodeBcd(version & 0xff));
  75 }
  76
  77 UsbMidiDescriptorParser::UsbMidiDescriptorParser()
  78     : is_parsing_usb_midi_interface_(false),
  79       current_endpoint_address_(0),
  80       current_cable_number_(0) {}
  81
  82 UsbMidiDescriptorParser::~UsbMidiDescriptorParser() {}
  83
  84 bool UsbMidiDescriptorParser::Parse(UsbMidiDevice* device,
  85                                     const uint8* data,
  86                                     size_t size,
  87                                     std::vector<UsbMidiJack>* jacks) {
  88   jacks->clear();
  89   bool result = ParseInternal(device, data, size, jacks);
  90   if (!result)
  91     jacks->clear();
  92   Clear();
  93   return result;
  94 }
  95
  96 bool UsbMidiDescriptorParser::ParseDeviceInfo(
  97     const uint8* data, size_t size, DeviceInfo* info) {
  98   *info = DeviceInfo();
  99   for (const uint8* current = data;
 100        current < data + size;
 101        current += current[0]) {
 102     uint8 length = current[0];
 103     if (length < 2) {
 104       DVLOG(1) << "Descriptor Type is not accessible.";
 105       return false;
 106     }
 107     if (current + length > data + size) {
 108       DVLOG(1) << "The header size is incorrect.";
 109       return false;
 110     }
 111     DescriptorType descriptor_type = static_cast<DescriptorType>(current[1]);
 112     if (descriptor_type != TYPE_DEVICE)
 113       continue;
 114     // We assume that ParseDevice doesn't modify |*info| if it returns false.
 115     return ParseDevice(current, length, info);
 116   }
 117   // No DEVICE descriptor is found.
 118   return false;
 119 }
 120
 121 bool UsbMidiDescriptorParser::ParseInternal(UsbMidiDevice* device,
 122                                             const uint8* data,
 123                                             size_t size,
 124                                             std::vector<UsbMidiJack>* jacks) {
 125   for (const uint8* current = data;
 126        current < data + size;
 127        current += current[0]) {
 128     uint8 length = current[0];
 129     if (length < 2) {
 130       DVLOG(1) << "Descriptor Type is not accessible.";
 131       return false;
 132     }
 133     if (current + length > data + size) {
 134       DVLOG(1) << "The header size is incorrect.";
 135       return false;
 136     }
 137     DescriptorType descriptor_type = static_cast<DescriptorType>(current[1]);
 138     if (descriptor_type != TYPE_INTERFACE && !is_parsing_usb_midi_interface_)
 139       continue;
 140
 141     switch (descriptor_type) {
 142       case TYPE_INTERFACE:
 143         if (!ParseInterface(current, length))
 144           return false;
 145         break;
 146       case TYPE_CS_INTERFACE:
 147         // We are assuming that the corresponding INTERFACE precedes
 148         // the CS_INTERFACE descriptor, as specified.
 149         if (!ParseCSInterface(device, current, length))
 150           return false;
 151         break;
 152       case TYPE_ENDPOINT:
 153         // We are assuming that endpoints are contained in an interface.
 154         if (!ParseEndpoint(current, length))
 155           return false;
 156         break;
 157       case TYPE_CS_ENDPOINT:
 158         // We are assuming that the corresponding ENDPOINT precedes
 159         // the CS_ENDPOINT descriptor, as specified.
 160         if (!ParseCSEndpoint(current, length, jacks))
 161           return false;
 162         break;
 163       default:
 164         // Ignore uninteresting types.
 165         break;
 166     }
 167   }
 168   return true;
 169 }
 170
 171 bool UsbMidiDescriptorParser::ParseDevice(
 172     const uint8* data, size_t size, DeviceInfo* info) {
 173   if (size < 0x12) {
 174     DVLOG(1) << "DEVICE header size is incorrect.";
 175     return false;
 176   }
 177
 178   info->vendor_id = data[8] | (data[9] << 8);
 179   info->product_id = data[0xa] | (data[0xb] << 8);
 180   info->bcd_device_version = data[0xc] | (data[0xd] << 8);
 181   info->manufacturer_index = data[0xe];
 182   info->product_index = data[0xf];
 183   return true;
 184 }
 185
 186 bool UsbMidiDescriptorParser::ParseInterface(const uint8* data, size_t size) {
 187   if (size != 9) {
 188     DVLOG(1) << "INTERFACE header size is incorrect.";
 189     return false;
 190   }
 191   incomplete_jacks_.clear();
 192
 193   uint8 interface_class = data[5];
 194   uint8 interface_subclass = data[6];
 195
 196   // All descriptors of endpoints contained in this interface
 197   // precede the next INTERFACE descriptor.
 198   is_parsing_usb_midi_interface_ =
 199       interface_class == kAudioInterfaceClass &&
 200       interface_subclass == kAudioMidiInterfaceSubclass;
 201   return true;
 202 }
 203
 204 bool UsbMidiDescriptorParser::ParseCSInterface(UsbMidiDevice* device,
 205                                                const uint8* data,
 206                                                size_t size) {
 207   // Descriptor Type and Descriptor Subtype should be accessible.
 208   if (size < 3) {
 209     DVLOG(1) << "CS_INTERFACE header size is incorrect.";
 210     return false;
 211   }
 212
 213   DescriptorSubType subtype = static_cast<DescriptorSubType>(data[2]);
 214
 215   if (subtype != SUBTYPE_MIDI_OUT_JACK &&
 216       subtype != SUBTYPE_MIDI_IN_JACK)
 217     return true;
 218
 219   if (size < 6) {
 220     DVLOG(1) << "CS_INTERFACE (MIDI JACK) header size is incorrect.";
 221     return false;
 222   }
 223   uint8 jack_type = data[3];
 224   uint8 id = data[4];
 225   if (jack_type == JACK_TYPE_EMBEDDED) {
 226     // We can't determine the associated endpoint now.
 227     incomplete_jacks_.push_back(UsbMidiJack(device, id, 0, 0));
 228   }
 229   return true;
 230 }
 231
 232 bool UsbMidiDescriptorParser::ParseEndpoint(const uint8* data, size_t size) {
 233   if (size < 4) {
 234     DVLOG(1) << "ENDPOINT header size is incorrect.";
 235     return false;
 236   }
 237   current_endpoint_address_ = data[2];
 238   current_cable_number_ = 0;
 239   return true;
 240 }
 241
 242 bool UsbMidiDescriptorParser::ParseCSEndpoint(const uint8* data,
 243                                               size_t size,
 244                                               std::vector<UsbMidiJack>* jacks) {
 245   const size_t kSizeForEmptyJacks = 4;
 246   // CS_ENDPOINT must be of size 4 + n where n is the number of associated
 247   // jacks.
 248   if (size < kSizeForEmptyJacks) {
 249     DVLOG(1) << "CS_ENDPOINT header size is incorrect.";
 250     return false;
 251   }
 252   uint8 num_jacks = data[3];
 253   if (size != kSizeForEmptyJacks + num_jacks) {
 254     DVLOG(1) << "CS_ENDPOINT header size is incorrect.";
 255     return false;
 256   }
 257
 258   for (size_t i = 0; i < num_jacks; ++i) {
 259     uint8 jack = data[kSizeForEmptyJacks + i];
 260     std::vector<UsbMidiJack>::iterator it =
 261         std::find_if(incomplete_jacks_.begin(),
 262                      incomplete_jacks_.end(),
 263                      JackMatcher(jack));
 264     if (it == incomplete_jacks_.end()) {
 265       DVLOG(1) << "A non-existing MIDI jack is associated.";
 266       return false;
 267     }
 268     if (current_cable_number_ > 0xf) {
 269       DVLOG(1) << "Cable number should range from 0x0 to 0xf.";
 270       return false;
 271     }
 272     // CS_ENDPOINT follows ENDPOINT and hence we can use the following
 273     // member variables.
 274     it->cable_number = current_cable_number_++;
 275     it->endpoint_address = current_endpoint_address_;
 276     jacks->push_back(*it);
 277     incomplete_jacks_.erase(it);
 278   }
 279   return true;
 280 }
 281
 282 void UsbMidiDescriptorParser::Clear() {
 283   is_parsing_usb_midi_interface_ = false;
 284   current_endpoint_address_ = 0;
 285   current_cable_number_ = 0;
 286   incomplete_jacks_.clear();
 287 }
 288
 289 }  // namespace midi
 290 }  // namespace media