components/url_formatter/idn_spoof_checker.h

// 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.

#ifndef COMPONENTS_URL_FORMATTER_IDN_SPOOF_CHECKER_H_
#define COMPONENTS_URL_FORMATTER_IDN_SPOOF_CHECKER_H_

#include <memory>
#include <string>

#include "base/strings/string16.h"
#include "base/strings/string_piece.h"
#include "third_party/icu/source/common/unicode/uniset.h"
#include "third_party/icu/source/common/unicode/utypes.h"
#include "third_party/icu/source/common/unicode/uversion.h"

// 'icu' does not work. Use U_ICU_NAMESPACE.
namespace U_ICU_NAMESPACE {

class UnicodeString;

}  // namespace U_ICU_NAMESPACE

struct USpoofChecker;

namespace url_formatter {

// A helper class for IDN Spoof checking, used to ensure that no IDN input is
// spoofable per Chromium's standard of spoofability. For a more thorough
// explanation of how spoof checking works in Chromium, see
// http://dev.chromium.org/developers/design-documents/idn-in-google-chrome .

class IDNSpoofChecker {
 public:
  IDNSpoofChecker();
  ~IDNSpoofChecker();

  // Returns true if |label| is safe to display as Unicode. In the event of
  // library failure, all IDN inputs will be treated as unsafe.
  // See the function body for details on the specific safety checks performed.
  bool SafeToDisplayAsUnicode(base::StringPiece16 label, bool is_tld_ascii);

 private:
  // Sets allowed characters in IDN labels and turns on USPOOF_CHAR_LIMIT.
  void SetAllowedUnicodeSet(UErrorCode* status);
  // Returns true if all the Cyrillic letters in |label| belong to a set of
  // Cyrillic letters that look like ASCII Latin letters.
  bool IsMadeOfLatinAlikeCyrillic(const icu::UnicodeString& label);

  USpoofChecker* checker_;
  icu::UnicodeSet deviation_characters_;
  icu::UnicodeSet non_ascii_latin_letters_;
  icu::UnicodeSet kana_letters_exceptions_;
  icu::UnicodeSet cyrillic_letters_;
  icu::UnicodeSet cyrillic_letters_latin_alike_;

  IDNSpoofChecker(const IDNSpoofChecker&) = delete;
  void operator=(const IDNSpoofChecker&) = delete;
};

}  // namespace url_formatter

#endif  // COMPONENTS_URL_FORMATTER_IDN_SPOOF_CHECKER_H_