Mitigate spoofing attempt using Latin letters.

components/url_formatter/top_domains/make_top_domain_gperf.cc

+// Copyright (c) 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 <algorithm>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include "base/base_paths.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/i18n/icu_util.h"
+#include "base/path_service.h"
+#include "base/strings/string_split.h"
+#include "base/strings/string_util.h"
+#include "third_party/icu/source/common/unicode/unistr.h"
+#include "third_party/icu/source/common/unicode/utypes.h"
+#include "third_party/icu/source/i18n/unicode/uspoof.h"
+
+std::string GetSkeleton(const std::string& domain,
+                        const USpoofChecker* spoof_checker) {
+  UErrorCode status = U_ZERO_ERROR;
+  icu::UnicodeString ustr_skeleton;
+  uspoof_getSkeletonUnicodeString(spoof_checker, 0, /* not used */
+                                  icu::UnicodeString::fromUTF8(domain),
+                                  ustr_skeleton, &status);
+  std::string skeleton;
+  return U_SUCCESS(status) ? ustr_skeleton.toUTF8String(skeleton) : skeleton;
+}
+
+base::FilePath GetPath(base::StringPiece basename) {
+  base::FilePath path;
+  base::PathService::Get(base::DIR_SOURCE_ROOT, &path);
+  return path.Append(FILE_PATH_LITERAL("components"))
+             .Append(FILE_PATH_LITERAL("url_formatter"))
+             .Append(FILE_PATH_LITERAL("top_domains")).AppendASCII(basename);
+}
+
+bool WriteToFile(const std::string& content, base::StringPiece basename) {
+  base::FilePath path = GetPath(basename);
+  if (base::WriteFile(path, content.data(), content.size()) == -1) {
+    std::cerr << "failed to write to " << path.AsUTF8Unsafe()

[Peter Kasting, 2017/05/09 01:37:02]

Nit: Initial caps?  (several places)

[jungshik at Google, 2017/05/10 18:05:12]

Done.

+              << '\n';
+    return false;
+  }
+  return true;

[Peter Kasting, 2017/05/09 01:37:02]

Nit: Shorter:

  bool succeeded = base::WriteFile(path, content.data(), content.size()) != -1;
  if (!succeeded)
    std::cerr << "failed to write to " << path.AsUTF8Unsafe() << '\n';
  return succeeded;

...though I wonder if "!= -1" should be a check that you actually wrote the full
size expected.

[jungshik at Google, 2017/05/10 18:05:12]

Ok. Turned it into CHECK.

+}
+
+int main(int argc, const char** argv) {
+  if (argc != 1) {
+    std::cerr << "Generate the list of top domain skeletons to use as\n"

[Peter Kasting, 2017/05/09 01:37:03]

Nit: Generates

Seems like this could be wrapped closer to 80 columns of output too.  Something
like this (which also takes into account the next two comments):

    std::cerr << "Generates the list of top domain skeletons to use as input to"
                 "\nbase/dafsa/make_dafsa.py.\nUsage: " << argv[0] << '\n';

[jungshik at Google, 2017/05/10 18:05:12]

Done.

+              << "input to base/dafsa/make_dafsa.py\n";

[Peter Kasting, 2017/05/09 01:37:02]

Nit: Leading << not necessary when continuing previous string constant (several
places)

[jungshik at Google, 2017/05/10 18:05:12]

Done.

+    std::cerr << "Usage: " << argv[0] << '\n';

[Peter Kasting, 2017/05/09 01:37:02]

Nit: Why not just continue << from the previous statement?

[jungshik at Google, 2017/05/10 18:05:13]

Done.

+    return 1;
+  }
+
+
+  base::i18n::InitializeICU();
+
+  base::FilePath input_file = GetPath("alexa_domains.list");
+  std::string input_content;
+  if (!base::ReadFileToString(input_file, &input_content)) {
+    std::cerr << "failed to read the input file " << input_file.AsUTF8Unsafe()
+              << '\n';
+    return 1;
+  }
+
+  UErrorCode status = U_ZERO_ERROR;
+  USpoofChecker* spoof_checker = uspoof_open(&status);
+  if (U_FAILURE(status)) {
+    std::cerr << "failed to create an ICU uspoof_checker due to "
+              << u_errorName(status) << ".\n";
+    return 1;
+  }
+
+  std::stringstream input(input_content);
+  std::stringstream output;

[Peter Kasting, 2017/05/09 01:37:02]

As far as I can tell, you just append unformatted strings to this.  Any reason
not to just use a string and += directly?

[jungshik at Google, 2017/05/10 18:05:13]

You.re right. Thank you for catching it.
 At first, it's an ostream to a file which I later turned to stringstream
without thinking much when rewriting to use base::Path, etc. Changed to
std::string and "+=". 

+
+  output << "// Copyright 2017 The Chromium Authors. All rights reserved.\n"
+         << "// Use of this source code is governed by a BSD-style license that"
+         << " can be\n"
+         << "// found in the LICENSE file.\n\n"
+         << "// This file is generated by "
+         << "components/url_formatter/make_top_domain_gperf.\n"
+         << "// DO NOT MANUALLY EDIT!\n\n"
+         << "// Each entry is the skeleton of a top domain for the "
+         << "confusability check.\n"

[Peter Kasting, 2017/05/09 01:37:02]

Nit: "...for the confusability check in <sourcefile name>" (or <function_name>)?

[jungshik at Google, 2017/05/10 18:05:12]

Done.

+         << "%%\n";
+
+  std::string domain;
+  size_t max_labels = 0;
+  std::string domains_with_max_labels;

[Peter Kasting, 2017/05/09 01:37:02]

Nit: domain, singular?

[jungshik at Google, 2017/05/10 18:05:12]

Done.

+  while (std::getline(input, domain)) {
+    if (domain[0] == '#') continue;
+    std::string skeleton = GetSkeleton(domain, spoof_checker);
+    if (skeleton.empty()) {
+      std::cerr << "failed to generate the skeleton of " << domain << '\n';
+      output << "// " << domain << '\n';
+    } else {
+      output << skeleton << ", 1\n";
+    }
+    std::vector<base::StringPiece> labels =
+        base::SplitStringPiece(domain, ".", base::TRIM_WHITESPACE,
+                               base::SPLIT_WANT_ALL);
+    if (labels.size() > max_labels) {
+      domains_with_max_labels = domain;
+      max_labels = labels.size();
+    }
+

[Peter Kasting, 2017/05/09 01:37:02]

Nit: No blank line

[jungshik at Google, 2017/05/10 18:05:12]

Done.

+  }
+
+  output << "%%\n";
+
+  if (!WriteToFile(output.str(), "alexa_skeletons.gperf"))
+    return 1;
+
+  std::cout << "The first domain with the largest number of labels is "
+            << domains_with_max_labels << " and has " << max_labels
+            << " labels.\n";
+
+  return 0;
+}