[Media Router] Parse device description xml in utility process

chrome/utility/media_router/dial_device_description_parser_impl.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/utility/media_router/dial_device_description_parser_impl.h"
+
+#include <libxml/parser.h>
+#include <libxml/tree.h>
+#include <libxml/xpath.h>
+
+#include "base/strings/string_util.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "third_party/libxml/chromium/libxml_utils.h"
+
+namespace {
+
+static std::string Validate(
+    const media_router::DialDeviceDescription& description) {
+  if (description.unique_id.empty()) {
+    return "Missing uniqueId";
+  }
+  if (description.friendly_name.empty()) {
+    return "Missing friendlyName";
+  }
+  return "";
+}
+
+// If friendly name does not exist, fall back to use model name + last 4
+// digits of UUID as friendly name.
+void ComputeFriendlyName(media_router::DialDeviceDescription* out) {
+  if (!out->friendly_name.empty())

[mark a. foltz, 2017/03/21 01:39:21]

For clarity I would move this check back out to the Parse method, as there's
nothing to compute unless the friendly_name is already empty.

[zhaobin, 2017/03/21 03:15:38]

Done.

+    return;
+
+  auto model_name = out->model_name;
+  auto unique_id = out->unique_id;
+
+  if (!model_name.empty() && unique_id.length() >= 4) {
+    out->friendly_name =
+        model_name + "[" + unique_id.substr(unique_id.length() - 4) + "]";

[mark a. foltz, 2017/03/21 01:39:21]

Nit: Can you add a space before [

[zhaobin, 2017/03/21 03:15:38]

Done.

+  }
+}
+
+// Replaces "<element_name>content</element_name>" with
+// "<element_name>***</element_name>"
+void 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)

[mark a. foltz, 2017/03/21 01:39:22]

&& end_pos > start_pos

[zhaobin, 2017/03/21 03:15:38]

Done.

+    xml_text.replace(start_pos, end_pos - start_pos, "***");
+}
+
+}  // namespace
+
+namespace media_router {
+
+DialDeviceDescriptionParserImpl::DialDeviceDescriptionParserImpl() = default;
+DialDeviceDescriptionParserImpl::~DialDeviceDescriptionParserImpl() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+// static
+void DialDeviceDescriptionParserImpl::Create(
+    chrome::mojom::DialDeviceDescriptionParserRequest request) {
+  mojo::MakeStrongBinding(base::MakeUnique<DialDeviceDescriptionParserImpl>(),
+                          std::move(request));
+}
+
+void DialDeviceDescriptionParserImpl::ParseDialDeviceDescription(
+    const std::string& device_description_xml_data,
+    const ParseDialDeviceDescriptionCallback& callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!callback.is_null());
+
+  media_router::DialDeviceDescription device_description;
+  bool result = Parse(device_description_xml_data, &device_description);
+  std::string logging_xml = ScrubXmlForLogging(device_description_xml_data);
+
+  callback.Run(result, device_description, logging_xml);
+}
+
+bool DialDeviceDescriptionParserImpl::Parse(
+    const std::string& xml,
+    media_router::DialDeviceDescription* out) {
+  DCHECK(out);
+
+  XmlReader xml_reader;
+  if (!xml_reader.Load(xml))
+    return false;
+
+  while (xml_reader.Read()) {
+    xml_reader.SkipToElement();
+    std::string node_name(xml_reader.NodeName());
+
+    if (node_name == "UDN") {
+      if (!xml_reader.ReadElementContent(&out->unique_id))
+        return false;
+    } else if (node_name == "friendlyName") {
+      if (!xml_reader.ReadElementContent(&out->friendly_name))
+        return false;
+    } else if (node_name == "modelName") {
+      if (!xml_reader.ReadElementContent(&out->model_name))
+        return false;
+    } else if (node_name == "deviceType") {
+      if (!xml_reader.ReadElementContent(&out->device_type))
+        return false;
+    }
+  }
+
+  ComputeFriendlyName(out);
+
+  std::string error = Validate(*out);
+  if (!error.empty()) {
+    DLOG(WARNING) << "Device description failed to validate: " << error;
+    return false;
+  }
+
+  return true;
+}
+
+std::string DialDeviceDescriptionParserImpl::ScrubXmlForLogging(
+    const std::string& xml_text) {
+  std::string scrubbed_xml(xml_text);
+  Scrub("UDN", scrubbed_xml);
+  Scrub("serialNumber", scrubbed_xml);
+  return scrubbed_xml;
+}
+
+}  // namespace media_router