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
11namespace media {
12
13namespace {
14
15// The constants below are specified in USB spec, USB audio spec
16// and USB midi spec.
17
18enum DescriptorType {
19  TYPE_DEVICE = 1,
20  TYPE_CONFIGURATION = 2,
21  TYPE_STRING = 3,
22  TYPE_INTERFACE = 4,
23  TYPE_ENDPOINT = 5,
24  TYPE_DEVICE_QUALIFIER = 6,
25  TYPE_OTHER_SPEED_CONFIGURATION = 7,
26  TYPE_INTERFACE_POWER = 8,
27
28  TYPE_CS_INTERFACE = 36,
29  TYPE_CS_ENDPOINT = 37,
30};
31
32enum DescriptorSubType {
33  SUBTYPE_MS_DESCRIPTOR_UNDEFINED = 0,
34  SUBTYPE_MS_HEADER = 1,
35  SUBTYPE_MIDI_IN_JACK = 2,
36  SUBTYPE_MIDI_OUT_JACK = 3,
37  SUBTYPE_ELEMENT = 4,
38};
39
40enum JackType {
41  JACK_TYPE_UNDEFINED = 0,
42  JACK_TYPE_EMBEDDED = 1,
43  JACK_TYPE_EXTERNAL = 2,
44};
45
46const uint8 kAudioInterfaceClass = 1;
47const uint8 kAudioMidiInterfaceSubclass = 3;
48
49class JackMatcher {
50 public:
51  explicit JackMatcher(uint8 id) : id_(id) {}
52
53  bool operator() (const UsbMidiJack& jack) const {
54    return jack.jack_id == id_;
55  }
56
57 private:
58  uint8 id_;
59};
60
61}  // namespace
62
63UsbMidiDescriptorParser::UsbMidiDescriptorParser()
64    : is_parsing_usb_midi_interface_(false),
65      current_endpoint_address_(0),
66      current_cable_number_(0) {}
67
68UsbMidiDescriptorParser::~UsbMidiDescriptorParser() {}
69
70bool UsbMidiDescriptorParser::Parse(UsbMidiDevice* device,
71                                    const uint8* data,
72                                    size_t size,
73                                    std::vector<UsbMidiJack>* jacks) {
74  jacks->clear();
75  bool result = ParseInternal(device, data, size, jacks);
76  if (!result)
77    jacks->clear();
78  Clear();
79  return result;
80}
81
82bool UsbMidiDescriptorParser::ParseInternal(UsbMidiDevice* device,
83                                            const uint8* data,
84                                            size_t size,
85                                            std::vector<UsbMidiJack>* jacks) {
86  for (const uint8* current = data;
87       current < data + size;
88       current += current[0]) {
89    uint8 length = current[0];
90    if (length < 2) {
91      DVLOG(1) << "Descriptor Type is not accessible.";
92      return false;
93    }
94    if (current + length > data + size) {
95      DVLOG(1) << "The header size is incorrect.";
96      return false;
97    }
98    DescriptorType descriptor_type = static_cast<DescriptorType>(current[1]);
99    if (descriptor_type != TYPE_INTERFACE && !is_parsing_usb_midi_interface_)
100      continue;
101
102    switch (descriptor_type) {
103      case TYPE_INTERFACE:
104        if (!ParseInterface(current, length))
105          return false;
106        break;
107      case TYPE_CS_INTERFACE:
108        // We are assuming that the corresponding INTERFACE precedes
109        // the CS_INTERFACE descriptor, as specified.
110        if (!ParseCSInterface(device, current, length))
111          return false;
112        break;
113      case TYPE_ENDPOINT:
114        // We are assuming that endpoints are contained in an interface.
115        if (!ParseEndpoint(current, length))
116          return false;
117        break;
118      case TYPE_CS_ENDPOINT:
119        // We are assuming that the corresponding ENDPOINT precedes
120        // the CS_ENDPOINT descriptor, as specified.
121        if (!ParseCSEndpoint(current, length, jacks))
122          return false;
123        break;
124      default:
125        // Ignore uninteresting types.
126        break;
127    }
128  }
129  return true;
130}
131
132bool UsbMidiDescriptorParser::ParseInterface(const uint8* data, size_t size) {
133  if (size != 9) {
134    DVLOG(1) << "INTERFACE header size is incorrect.";
135    return false;
136  }
137  incomplete_jacks_.clear();
138
139  uint8 interface_class = data[5];
140  uint8 interface_subclass = data[6];
141
142  // All descriptors of endpoints contained in this interface
143  // precede the next INTERFACE descriptor.
144  is_parsing_usb_midi_interface_ =
145      interface_class == kAudioInterfaceClass &&
146      interface_subclass == kAudioMidiInterfaceSubclass;
147  return true;
148}
149
150bool UsbMidiDescriptorParser::ParseCSInterface(UsbMidiDevice* device,
151                                               const uint8* data,
152                                               size_t size) {
153  // Descriptor Type and Descriptor Subtype should be accessible.
154  if (size < 3) {
155    DVLOG(1) << "CS_INTERFACE header size is incorrect.";
156    return false;
157  }
158
159  DescriptorSubType subtype = static_cast<DescriptorSubType>(data[2]);
160
161  if (subtype != SUBTYPE_MIDI_OUT_JACK &&
162      subtype != SUBTYPE_MIDI_IN_JACK)
163    return true;
164
165  if (size < 6) {
166    DVLOG(1) << "CS_INTERFACE (MIDI JACK) header size is incorrect.";
167    return false;
168  }
169  uint8 jack_type = data[3];
170  uint8 id = data[4];
171  if (jack_type == JACK_TYPE_EMBEDDED) {
172    // We can't determine the associated endpoint now.
173    incomplete_jacks_.push_back(UsbMidiJack(device, id, 0, 0));
174  }
175  return true;
176}
177
178bool UsbMidiDescriptorParser::ParseEndpoint(const uint8* data, size_t size) {
179  if (size < 4) {
180    DVLOG(1) << "ENDPOINT header size is incorrect.";
181    return false;
182  }
183  current_endpoint_address_ = data[2];
184  current_cable_number_ = 0;
185  return true;
186}
187
188bool UsbMidiDescriptorParser::ParseCSEndpoint(const uint8* data,
189                                              size_t size,
190                                              std::vector<UsbMidiJack>* jacks) {
191  const size_t kSizeForEmptyJacks = 4;
192  // CS_ENDPOINT must be of size 4 + n where n is the number of associated
193  // jacks.
194  if (size < kSizeForEmptyJacks) {
195    DVLOG(1) << "CS_ENDPOINT header size is incorrect.";
196    return false;
197  }
198  uint8 num_jacks = data[3];
199  if (size != kSizeForEmptyJacks + num_jacks) {
200    DVLOG(1) << "CS_ENDPOINT header size is incorrect.";
201    return false;
202  }
203
204  for (size_t i = 0; i < num_jacks; ++i) {
205    uint8 jack = data[kSizeForEmptyJacks + i];
206    std::vector<UsbMidiJack>::iterator it =
207        std::find_if(incomplete_jacks_.begin(),
208                     incomplete_jacks_.end(),
209                     JackMatcher(jack));
210    if (it == incomplete_jacks_.end()) {
211      DVLOG(1) << "A non-existing MIDI jack is associated.";
212      return false;
213    }
214    if (current_cable_number_ > 0xf) {
215      DVLOG(1) << "Cable number should range from 0x0 to 0xf.";
216      return false;
217    }
218    // CS_ENDPOINT follows ENDPOINT and hence we can use the following
219    // member variables.
220    it->cable_number = current_cable_number_++;
221    it->endpoint_address = current_endpoint_address_;
222    jacks->push_back(*it);
223    incomplete_jacks_.erase(it);
224  }
225  return true;
226}
227
228void UsbMidiDescriptorParser::Clear() {
229  is_parsing_usb_midi_interface_ = false;
230  current_endpoint_address_ = 0;
231  current_cable_number_ = 0;
232  incomplete_jacks_.clear();
233}
234
235}  // namespace media
236