device/usb/webusb_descriptors.cc

   1 // Copyright 2015 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 <iterator>
   6
   7 #include "base/logging.h"
   8 #include "device/usb/webusb_descriptors.h"
   9
  10 namespace device {
  11
  12 namespace {
  13
  14 // These constants are defined by the Universal Serial Device 3.0 Specification
  15 // Revision 1.0.
  16 const uint8_t kBosDescriptorType = 0x0F;
  17 const uint8_t kDeviceCapabilityDescriptorType = 0x10;
  18
  19 const uint8_t kPlatformDevCapabilityType = 0x05;
  20
  21 // These constants are defined by the WebUSB specification:
  22 // http://reillyeon.github.io/webusb/
  23 const uint8_t kWebUsbCapabilityUUID[16] = {
  24     // Little-endian encoding of {3408b638-09a9-47a0-8bfd-a0768815b665}.
  25     0x38, 0xB6, 0x08, 0x34, 0xA9, 0x09, 0xA0, 0x47,
  26     0x8B, 0xFD, 0xA0, 0x76, 0x88, 0x15, 0xB6, 0x65};
  27
  28 const uint8_t kDescriptorSetDescriptorType = 0x00;
  29 const uint8_t kConfigurationSubsetDescriptorType = 0x01;
  30 const uint8_t kFunctionSubsetDescriptorType = 0x02;
  31 const uint8_t kUrlDescriptorType = 0x03;
  32
  33 bool ParseUrl(GURL* url,
  34               std::vector<uint8_t>::const_iterator* it,
  35               std::vector<uint8_t>::const_iterator end) {
  36   // These conditions must be guaranteed by the caller.
  37   DCHECK(*it != end);
  38   uint8_t length = (*it)[0];
  39   DCHECK_LE(length, std::distance(*it, end));
  40   DCHECK_GE(length, 2);
  41   DCHECK_EQ((*it)[1], kUrlDescriptorType);
  42
  43   if (length == 2) {
  44     return false;
  45   }
  46
  47   const char* str = reinterpret_cast<const char*>(&(*it)[2]);
  48   *url = GURL(std::string(str, length - 2));
  49   if (!url->is_valid()) {
  50     return false;
  51   }
  52
  53   std::advance(*it, length);
  54   return true;
  55 }
  56
  57 bool ParseFunction(WebUsbFunctionSubset* function,
  58                    std::vector<uint8_t>::const_iterator* it,
  59                    std::vector<uint8_t>::const_iterator end) {
  60   // These conditions must be guaranteed by the caller.
  61   DCHECK(*it != end);
  62   uint8_t length = (*it)[0];
  63   DCHECK_LE(length, std::distance(*it, end));
  64   DCHECK_GE(length, 2);
  65   DCHECK_EQ((*it)[1], kFunctionSubsetDescriptorType);
  66
  67   if (length != 5) {
  68     return false;
  69   }
  70
  71   function->first_interface = (*it)[2];
  72
  73   // Validate the Function Subset header.
  74   uint16_t total_length = (*it)[3] + ((*it)[4] << 8);
  75   if (length > total_length || total_length > std::distance(*it, end)) {
  76     return false;
  77   }
  78
  79   end = *it + total_length;
  80   std::advance(*it, length);
  81
  82   while (*it != end) {
  83     uint8_t length = (*it)[0];
  84     if (length < 2 || std::distance(*it, end) < length) {
  85       return false;
  86     }
  87
  88     uint8_t type = (*it)[1];
  89     if (type == kUrlDescriptorType) {
  90       GURL origin;
  91       if (!ParseUrl(&origin, it, end)) {
  92         return false;
  93       }
  94       function->origins.push_back(origin);
  95     } else {
  96       return false;
  97     }
  98   }
  99
 100   return true;
 101 }
 102
 103 bool ParseConfiguration(WebUsbConfigurationSubset* configuration,
 104                         std::vector<uint8_t>::const_iterator* it,
 105                         std::vector<uint8_t>::const_iterator end) {
 106   // These conditions must be guaranteed by the caller.
 107   DCHECK(*it != end);
 108   uint8_t length = (*it)[0];
 109   DCHECK_LE(length, std::distance(*it, end));
 110   DCHECK_GE(length, 2);
 111   DCHECK_EQ((*it)[1], kConfigurationSubsetDescriptorType);
 112
 113   if (length != 5) {
 114     return false;
 115   }
 116
 117   configuration->configuration_value = (*it)[2];
 118
 119   // Validate the Configuration Subset header.
 120   uint16_t total_length = (*it)[3] + ((*it)[4] << 8);
 121   if (length > total_length || total_length > std::distance(*it, end)) {
 122     return false;
 123   }
 124
 125   end = *it + total_length;
 126   std::advance(*it, length);
 127
 128   while (*it != end) {
 129     uint8_t length = (*it)[0];
 130     if (length < 2 || std::distance(*it, end) < length) {
 131       return false;
 132     }
 133
 134     uint8_t type = (*it)[1];
 135     if (type == kFunctionSubsetDescriptorType) {
 136       WebUsbFunctionSubset function;
 137       if (!ParseFunction(&function, it, end)) {
 138         return false;
 139       }
 140       configuration->functions.push_back(function);
 141     } else if (type == kUrlDescriptorType) {
 142       GURL origin;
 143       if (!ParseUrl(&origin, it, end)) {
 144         return false;
 145       }
 146       configuration->origins.push_back(origin);
 147     } else {
 148       return false;
 149     }
 150   }
 151
 152   return true;
 153 }
 154
 155 }  // namespace
 156
 157 WebUsbFunctionSubset::WebUsbFunctionSubset() : first_interface(0) {}
 158
 159 WebUsbFunctionSubset::~WebUsbFunctionSubset() {}
 160
 161 WebUsbConfigurationSubset::WebUsbConfigurationSubset()
 162     : configuration_value(0) {}
 163
 164 WebUsbConfigurationSubset::~WebUsbConfigurationSubset() {}
 165
 166 WebUsbDescriptorSet::WebUsbDescriptorSet() {}
 167
 168 WebUsbDescriptorSet::~WebUsbDescriptorSet() {}
 169
 170 bool WebUsbDescriptorSet::Parse(const std::vector<uint8_t>& bytes) {
 171   if (bytes.size() < 4) {
 172     return false;
 173   }
 174
 175   // Validate the descriptor set header.
 176   uint16_t total_length = bytes[2] + (bytes[3] << 8);
 177   if (bytes[0] != 4 ||                                    // bLength
 178       bytes[1] != kDescriptorSetDescriptorType ||         // bDescriptorType
 179       4 > total_length || total_length > bytes.size()) {  // wTotalLength
 180     return false;
 181   }
 182
 183   std::vector<uint8_t>::const_iterator it = bytes.begin();
 184   std::vector<uint8_t>::const_iterator end = it + total_length;
 185   std::advance(it, 4);
 186
 187   while (it != bytes.end()) {
 188     uint8_t length = it[0];
 189     if (length < 2 || std::distance(it, end) < length) {
 190       return false;
 191     }
 192
 193     uint8_t type = it[1];
 194     if (type == kConfigurationSubsetDescriptorType) {
 195       WebUsbConfigurationSubset configuration;
 196       if (!ParseConfiguration(&configuration, &it, end)) {
 197         return false;
 198       }
 199       configurations.push_back(configuration);
 200     } else if (type == kUrlDescriptorType) {
 201       GURL origin;
 202       if (!ParseUrl(&origin, &it, end)) {
 203         return false;
 204       }
 205       origins.push_back(origin);
 206     } else {
 207       return false;
 208     }
 209   }
 210
 211   return true;
 212 }
 213
 214 WebUsbPlatformCapabilityDescriptor::WebUsbPlatformCapabilityDescriptor()
 215     : version(0), vendor_code(0) {}
 216
 217 WebUsbPlatformCapabilityDescriptor::~WebUsbPlatformCapabilityDescriptor() {}
 218
 219 bool WebUsbPlatformCapabilityDescriptor::ParseFromBosDescriptor(
 220     const std::vector<uint8_t>& bytes) {
 221   if (bytes.size() < 5) {
 222     // Too short for the BOS descriptor header.
 223     return false;
 224   }
 225
 226   // Validate the BOS descriptor, defined in Table 9-12 of the Universal Serial
 227   // Bus 3.1 Specification, Revision 1.0.
 228   uint16_t total_length = bytes[2] + (bytes[3] << 8);
 229   if (bytes[0] != 5 ||                                    // bLength
 230       bytes[1] != kBosDescriptorType ||                   // bDescriptorType
 231       5 > total_length || total_length > bytes.size()) {  // wTotalLength
 232     return false;
 233   }
 234
 235   uint8_t num_device_caps = bytes[4];
 236   std::vector<uint8_t>::const_iterator it = bytes.begin();
 237   std::vector<uint8_t>::const_iterator end = it + total_length;
 238   std::advance(it, 5);
 239
 240   uint8_t length = 0;
 241   bool found_vendor_code = false;
 242   for (size_t i = 0; i < num_device_caps; ++i, std::advance(it, length)) {
 243     if (it == end) {
 244       return false;
 245     }
 246
 247     // Validate the Device Capability descriptor, defined in Table 9-13 of the
 248     // Universal Serial Bus 3.1 Specification, Revision 1.0.
 249     length = it[0];
 250     if (length < 3 || std::distance(it, end) < length ||  // bLength
 251         it[1] != kDeviceCapabilityDescriptorType) {       // bDescriptorType
 252       return false;
 253     }
 254
 255     if (it[2] != kPlatformDevCapabilityType) {  // bDevCapabilityType
 256       continue;
 257     }
 258
 259     // Validate the Platform Capability Descriptor, defined in Table 9-18 of the
 260     // Universal Serial Bus 3.1 Specification, Revision 1.0.
 261     if (length < 20) {
 262       // Platform capability descriptors must be at least 20 bytes.
 263       return false;
 264     }
 265
 266     if (memcmp(&it[4], kWebUsbCapabilityUUID, sizeof(kWebUsbCapabilityUUID)) !=
 267         0) {  // PlatformCapabilityUUID
 268       continue;
 269     }
 270
 271     if (length < 23) {
 272       // The WebUSB capability descriptor must be at least 23 bytes (to allow
 273       // for future versions).
 274       return false;
 275     }
 276
 277     version = it[20] + (it[21] << 8);  // bcdVersion
 278     if (version < 0x0100) {
 279       continue;
 280     }
 281
 282     // Version 1.0 only defines a single field, bVendorCode.
 283     vendor_code = it[22];
 284     found_vendor_code = true;
 285   }
 286
 287   return found_vendor_code;
 288 }
 289
 290 }  // namespace device