[Media Router] Add DialMediaSinkService and DeviceDescriptionService

chrome/browser/media/router/device_description_service.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/media/router/device_description_service.h"
+
+#include "base/strings/string_util.h"
+#include "chrome/browser/extensions/api/dial/device_description_fetcher.h"
+#include "chrome/browser/extensions/api/dial/dial_device_data.h"
+#include "chrome/browser/profiles/profile.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/ip_address.h"
+#include "third_party/libxml/chromium/libxml_utils.h"
+#include "url/gurl.h"
+
+using base::Time;
+using base::TimeDelta;
+using content::BrowserThread;
+
+namespace {
+
+// How long to cache a device description.
+// TODO: Use value from chrome.dial when http://crbug.com/165289 is fixed.
+const int kDeviceDescriptionCacheTimeMillis = 30 * 60 * 1000;
+
+// Replaces "<element_name>content</element_name>" with
+// "<element_name>***</element_name>"
+bool Scrub(const std::string& element_name, std::string& xml_text) {
+  size_t pos = xml_text.find("<" + element_name + ">");
+  size_t end_pos = xml_text.find("</" + element_name + ">");
+  size_t start_pos = pos + element_name.length() + 2;
+
+  if (pos == std::string::npos || end_pos == std::string::npos)
+    return false;
+
+  xml_text.replace(start_pos, end_pos - start_pos, "***");
+  return true;
+}
+
+// Removes unique identifiers from the device description.
+// |xml_text|: xmlDoc The device description.
+// Returns false if <UDN> or <serialNumber> field does not exist in |xml_text|.
+bool ScrubDeviceDescription(std::string& xml_text) {
+  return Scrub("UDN", xml_text) && Scrub("serialNumber", xml_text);
+}
+
+// Validates whether a URL is valid for fetching device descriptions.
+// |descriptionUrl|: Device description URL.
+// Returns true if descriptionUrl is valid.
+static bool IsValidDeviceDescriptionUrl(const GURL& device_description_url) {
+  if (!device_description_url.SchemeIs(url::kHttpScheme))
+    return false;
+
+  net::IPAddress address;
+  if (!net::ParseURLHostnameToAddress(device_description_url.host(), &address))
+    return false;
+
+  return address.IsReserved();
+}
+
+static bool IsValidAppUrl(const GURL& app_url, const std::string& ip_address) {
+  return app_url.SchemeIs(url::kHttpScheme) && app_url.host() != ip_address;
+}
+
+static std::string Validate(
+    const media_router::DialDeviceDescription& description) {
+  if (description.device_label.empty()) {
+    return "Missing deviceLabel";
+  }
+  if (description.unique_id.empty()) {
+    return "Missing uniqueId";
+  }
+  if (description.friendly_name.empty()) {
+    return "Missing friendlyName";
+  }
+  if (description.ip_address.empty()) {
+    return "Missing ipAddress";
+  }
+  if (!description.app_url.is_valid()) {
+    return "Missing appUrl";
+  }
+  if (description.fetch_time_millis.is_null()) {
+    return "Missing fetchTimeMillis";
+  }
+  if (description.fetch_time_millis.is_null()) {
+    return "Missing expireTimeMillis";
+  }
+  if (IsValidAppUrl(description.app_url, description.ip_address)) {
+    return "Invalid appUrl";
+  }
+  return "";
+}
+
+static std::string ToString(
+    const media_router::DialDeviceDescription& description) {
+  std::stringstream ss;
+  ss << "DialDeviceDescription [unique_id]: " << description.unique_id
+     << " [device_label]: " << description.device_label
+     << " [friendly_name]: " << description.friendly_name
+     << " [ip_address]: " << description.ip_address
+     << " [app_url]: " << description.app_url
+     << " [fetch_time_millis]: " << description.fetch_time_millis
+     << " [expire_time_millis]: " << description.expire_time_millis
+     << " [device_type]: " << description.device_type
+     << " [model_name]: " << description.model_name
+     << " [config_id]: " << *description.config_id;
+
+  return ss.str();
+}
+
+}  // namespace
+
+namespace media_router {
+
+DialDeviceDescription::DialDeviceDescription() = default;
+DialDeviceDescription::~DialDeviceDescription() = default;
+DialDeviceDescription::DialDeviceDescription(
+    const DialDeviceDescription& other) = default;
+
+DeviceDescriptionService::DeviceDescriptionService(Observer* observer)
+    : observer_(observer) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(observer_);
+}
+
+DeviceDescriptionService::~DeviceDescriptionService() = default;
+
+bool DeviceDescriptionService::GetDeviceDescription(
+    const DialDeviceData& device,
+    net::URLRequestContextGetter* request_context,
+    DialDeviceDescription* out_description) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (CheckAndUpdateCache(device, out_description))
+    return true;
+
+  FetchDeviceDescription(device, request_context);
+  return false;
+}
+
+bool DeviceDescriptionService::MayStopDeviceDescriptionFetching(
+    const std::string& device_label) {
+  return device_description_fetcher_map_.erase(device_label) > 0;
+}
+
+void DeviceDescriptionService::FetchDeviceDescription(
+    const DialDeviceData& dial_device,
+    net::URLRequestContextGetter* request_context) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (!IsValidDeviceDescriptionUrl(dial_device.device_description_url())) {
+    std::string error_message = "Invalid device description URL: " +
+                                dial_device.device_description_url().spec();
+    OnDeviceDescriptionFetchError(dial_device, error_message);
+    return;
+  }
+
+  const auto& it = device_description_fetcher_map_.find(dial_device.label());
+  if (it != device_description_fetcher_map_.end()) {
+    if (it->second->device_description_url() ==
+        dial_device.device_description_url()) {
+      DVLOG(2) << "Pending request in progress [URL]: "
+               << dial_device.device_description_url();
+      return;
+    }
+    // Destroy fetcher and cancel HTTP request.
+    device_description_fetcher_map_.erase(it);
+  }
+
+  auto device_description_fetcher =
+      base::MakeUnique<extensions::api::dial::DeviceDescriptionFetcher::
+                           DeviceDescriptionFetcher>(
+          dial_device.device_description_url(), request_context,
+          BrowserThread::IO,
+          base::BindOnce(
+              &DeviceDescriptionService::OnDeviceDescriptionAvailable,
+              base::Unretained(this), dial_device),
+          base::BindOnce(
+              &DeviceDescriptionService::OnDeviceDescriptionFetchError,
+              base::Unretained(this), dial_device));
+
+  device_description_fetcher->Start();
+  device_description_fetcher_map_.insert(std::make_pair(
+      dial_device.label(), std::move(device_description_fetcher)));
+}
+
+bool DeviceDescriptionService::CheckAndUpdateCache(
+    const DialDeviceData& dial_device,
+    DialDeviceDescription* out_description) {
+  const auto& it = description_map_.find(dial_device.label());
+  if (it == description_map_.end())
+    return false;
+
+  // If the entry's configId does not match, or it has expired, remove it.
+  if (it->second.config_id != dial_device.config_id() ||
+      base::Time::Now() >= it->second.expire_time_millis) {
+    DVLOG(2) << "Removing invalid entry " << it->second.device_label;
+    description_map_.erase(it);
+    return false;
+  }
+  // Entry is valid.
+  (*out_description) = it->second;
+  return true;
+}
+
+bool DeviceDescriptionService::ProcessDeviceDescription(
+    const DialDeviceData& dial_device,
+    const std::string& xmlText,
+    const GURL& app_url,
+    DialDeviceDescription* description) {
+  if (!ParseDeviceDescription(dial_device, xmlText, app_url, description)) {
+    DVLOG(2) << "Invalid device description";
+    return false;
+  }
+  DVLOG(2) << "Got device description for " << description->device_label;
+  DVLOG(2) << "... device description was: " << ToString(*description);
+
+  // Stick it in the cache if the description has a config (version) id.
+  // NOTE: We could cache descriptions without a config id and rely on the
+  // timeout to eventually update the cache.
+  if (description->config_id) {
+    DVLOG(2) << "Caching device description for " << description->device_label;
+    description_map_.insert(std::make_pair(dial_device.label(), *description));
+  }
+  return true;
+}
+
+bool DeviceDescriptionService::ParseDeviceDescription(
+    const DialDeviceData& dial_device,
+    const std::string& xml_text,
+    const GURL& app_url,
+    DialDeviceDescription* description) {
+  XmlReader xml_reader;
+  if (!xml_reader.Load(xml_text))
+    return false;
+
+  description->fetch_time_millis = base::Time::Now();
+  description->expire_time_millis =
+      description->fetch_time_millis +
+      base::TimeDelta::FromMilliseconds(kDeviceDescriptionCacheTimeMillis);
+  description->device_label = dial_device.label();
+  description->config_id = dial_device.config_id();
+  description->ip_address = dial_device.device_description_url().host();
+  description->app_url = app_url;
+
+  while (xml_reader.Read()) {
+    xml_reader.SkipToElement();
+    std::string node_name(xml_reader.NodeName());
+
+    if (node_name == "deviceType") {
+      if (!xml_reader.ReadElementContent(&description->device_type))
+        return false;
+    } else if (node_name == "modelName") {
+      if (!xml_reader.ReadElementContent(&description->model_name))
+        return false;
+    } else if (node_name == "friendlyName") {
+      if (!xml_reader.ReadElementContent(&description->friendly_name))
+        return false;
+    } else if (node_name == "UDN") {
+      if (!xml_reader.ReadElementContent(&description->unique_id))
+        return false;
+    }
+  }
+
+  // If friendly name does not exist, fall back to use model name + last 4
+  // digits of UUID as friendly name.
+  if (description->friendly_name.empty() && !description->model_name.empty()) {
+    description->friendly_name = description->model_name;
+    if (!description->unique_id.empty()) {
+      description->friendly_name +=
+          '[' +
+          description->unique_id.substr(description->unique_id.length() - 4) +
+          ']';
+    }
+    DVLOG(2)
+        << "Fixed device description: created friendlyName from modelName.";
+  }
+
+  std::string xml_logging = xml_text;
+  if (ScrubDeviceDescription(xml_logging))
+    DVLOG(2) << "Device description: " << xml_logging;
+
+  std::string error = Validate(*description);
+  if (!error.empty()) {
+    DLOG(WARNING) << "Device description failed to validate: " << error;
+    return false;
+  }
+
+  return true;
+}
+
+void DeviceDescriptionService::OnDeviceDescriptionAvailable(
+    const extensions::api::dial::DialDeviceData& dial_device,
+    const extensions::api::dial::DialDeviceDescriptionData& description_data) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  DialDeviceDescription description;
+  if (ProcessDeviceDescription(dial_device, description_data.device_description,
+                               description_data.app_url, &description)) {
+    observer_->OnDeviceDescriptionAvailable(dial_device.label(), description);
+  } else {
+    observer_->OnDeviceDescriptionFetchError(dial_device.label(),
+                                             "Failed to process fetch result");
+  }
+
+  device_description_fetcher_map_.erase(dial_device.label());
+}
+
+void DeviceDescriptionService::OnDeviceDescriptionFetchError(
+    const extensions::api::dial::DialDeviceData& dial_device,
+    const std::string& error_message) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  DVLOG(2) << "OnDeviceDescriptionFetchError [label]: " << dial_device.label();
+
+  observer_->OnDeviceDescriptionFetchError(dial_device.label(), error_message);
+  device_description_fetcher_map_.erase(dial_device.label());
+}
+
+}  // namespace media_router