/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "MainThreadUtils.h"
#include "mozilla/ClearOnShutdown.h"
#include "mozilla/Preferences.h"
#include "nsIDNService.h"
#include "nsReadableUtils.h"
#include "nsCRT.h"
#include "nsServiceManagerUtils.h"
#include "nsString.h"
#include "nsStringFwd.h"
#include "nsUnicharUtils.h"
#include "nsUnicodeProperties.h"
#include "harfbuzz/hb.h"
#include "mozilla/Casting.h"
#include "mozilla/StaticPrefs_network.h"
#include "mozilla/intl/UnicodeProperties.h"
#include "mozilla/intl/UnicodeScriptCodes.h"
#include "nsNetUtil.h"
#include "nsStandardURL.h"

using namespace mozilla;
using namespace mozilla::intl;
using namespace mozilla::unicode;
using namespace mozilla::net;
using mozilla::Preferences;

//-----------------------------------------------------------------------------

#define ISDIGIT(c) ((c) >= '0' && (c) <= '9')

template <int N>
static inline bool TLDEqualsLiteral(mozilla::Span<const char32_t> aTLD,
                                    const char (&aStr)[N]) {
  if (aTLD.Length() != N - 1) {
    return false;
  }
  const char* a = aStr;
  for (const char32_t c : aTLD) {
    if (c != char32_t(*a)) {
      return false;
    }
    ++a;
  }
  return true;
}

template <int N>
static inline bool TLDStartsWith(mozilla::Span<const char32_t> aTLD,
                                 const char (&aStr)[N]) {
  // Ensure the span is long enough to contain the prefix
  if (aTLD.Length() < N - 1) {
    return false;
  }

  for (size_t i = 0; i < N - 1; ++i) {
    if (aTLD[i] != char32_t(aStr[i])) {
      return false;
    }
  }

  return true;
}

static inline bool isOnlySafeChars(mozilla::Span<const char32_t> aLabel,
                                   const nsTArray<BlocklistRange>& aBlocklist) {
  if (aBlocklist.IsEmpty()) {
    return true;
  }
  for (const char32_t c : aLabel) {
    if (c > 0xFFFF) {
      // The blocklist only support BMP!
      continue;
    }
    if (CharInBlocklist(char16_t(c), aBlocklist)) {
      return false;
    }
  }
  return true;
}

static bool isCyrillicDomain(mozilla::Span<const char32_t>& aTLD) {
  return TLDEqualsLiteral(aTLD, "bg") || TLDEqualsLiteral(aTLD, "by") ||
         TLDEqualsLiteral(aTLD, "kz") || TLDEqualsLiteral(aTLD, "pyc") ||
         TLDEqualsLiteral(aTLD, "ru") || TLDEqualsLiteral(aTLD, "su") ||
         TLDEqualsLiteral(aTLD, "ua") || TLDEqualsLiteral(aTLD, "uz");
}

//-----------------------------------------------------------------------------
// nsIDNService
//-----------------------------------------------------------------------------

/* Implementation file */
NS_IMPL_ISUPPORTS(nsIDNService, nsIIDNService)

nsresult nsIDNService::Init() {
  MOZ_ASSERT(NS_IsMainThread());
  InitializeBlocklist(mIDNBlocklist);

  InitCJKSlashConfusables();
  InitCJKIdeographs();
  InitDigitConfusables();
  InitCyrillicLatinConfusables();
  InitThaiLatinConfusables();
  return NS_OK;
}

void nsIDNService::InitCJKSlashConfusables() {
  mCJKSlashConfusables.Insert(0x30CE);  // ノ
  mCJKSlashConfusables.Insert(0x30BD);  // ソ
  mCJKSlashConfusables.Insert(0x30BE);  // ゾ
  mCJKSlashConfusables.Insert(0x30F3);  // ン
  mCJKSlashConfusables.Insert(0x4E36);  // 丶
  mCJKSlashConfusables.Insert(0x4E40);  // 乀
  mCJKSlashConfusables.Insert(0x4E41);  // 乁
  mCJKSlashConfusables.Insert(0x4E3F);  // 丿
}

void nsIDNService::InitCJKIdeographs() {
  mCJKIdeographs.Insert(0x4E00);  // 一
  mCJKIdeographs.Insert(0x3127);  // ㄧ
  mCJKIdeographs.Insert(0x4E28);  // 丨
  mCJKIdeographs.Insert(0x4E5B);  // 乛
  mCJKIdeographs.Insert(0x4E03);  // 七
  mCJKIdeographs.Insert(0x4E05);  // 丅
  mCJKIdeographs.Insert(0x5341);  // 十
  mCJKIdeographs.Insert(0x3007);  // 〇
  mCJKIdeographs.Insert(0x3112);  // ㄒ
  mCJKIdeographs.Insert(0x311A);  // ㄚ
  mCJKIdeographs.Insert(0x311F);  // ㄟ
  mCJKIdeographs.Insert(0x3128);  // ㄨ
  mCJKIdeographs.Insert(0x3129);  // ㄩ
  mCJKIdeographs.Insert(0x3108);  // ㄈ
  mCJKIdeographs.Insert(0x31BA);  // ㆺ
  mCJKIdeographs.Insert(0x31B3);  // ㆳ
  mCJKIdeographs.Insert(0x5DE5);  // 工
  mCJKIdeographs.Insert(0x31B2);  // ㆲ
  mCJKIdeographs.Insert(0x8BA0);  // 讠
  mCJKIdeographs.Insert(0x4E01);  // 丁
}

void nsIDNService::InitDigitConfusables() {
  mDigitConfusables.Insert(0x03B8);  // θ
  mDigitConfusables.Insert(0x0968);  // २
  mDigitConfusables.Insert(0x09E8);  // ২
  mDigitConfusables.Insert(0x0A68);  // ੨
  mDigitConfusables.Insert(0x0AE8);  // ૨
  mDigitConfusables.Insert(0x0CE9);  // ೩
  mDigitConfusables.Insert(0x0577);  // շ
  mDigitConfusables.Insert(0x0437);  // з
  mDigitConfusables.Insert(0x0499);  // ҙ
  mDigitConfusables.Insert(0x04E1);  // ӡ
  mDigitConfusables.Insert(0x0909);  // उ
  mDigitConfusables.Insert(0x0993);  // ও
  mDigitConfusables.Insert(0x0A24);  // ਤ
  mDigitConfusables.Insert(0x0A69);  // ੩
  mDigitConfusables.Insert(0x0AE9);  // ૩
  mDigitConfusables.Insert(0x0C69);  // ౩
  mDigitConfusables.Insert(0x1012);  // ဒ
  mDigitConfusables.Insert(0x10D5);  // ვ
  mDigitConfusables.Insert(0x10DE);  // პ
  mDigitConfusables.Insert(0x0A5C);  // ੜ
  mDigitConfusables.Insert(0x10D9);  // კ
  mDigitConfusables.Insert(0x0A6B);  // ੫
  mDigitConfusables.Insert(0x4E29);  // 丩
  mDigitConfusables.Insert(0x3110);  // ㄐ
  mDigitConfusables.Insert(0x0573);  // ճ
  mDigitConfusables.Insert(0x09EA);  // ৪
  mDigitConfusables.Insert(0x0A6A);  // ੪
  mDigitConfusables.Insert(0x0B6B);  // ୫
  mDigitConfusables.Insert(0x0AED);  // ૭
  mDigitConfusables.Insert(0x0B68);  // ୨
  mDigitConfusables.Insert(0x0C68);  // ౨
}

void nsIDNService::InitCyrillicLatinConfusables() {
  mCyrillicLatinConfusables.Insert(0x0430);  // а CYRILLIC SMALL LETTER A
  mCyrillicLatinConfusables.Insert(0x044B);  // ы CYRILLIC SMALL LETTER YERU
  mCyrillicLatinConfusables.Insert(0x0441);  // с CYRILLIC SMALL LETTER ES
  mCyrillicLatinConfusables.Insert(0x0501);  // ԁ CYRILLIC SMALL LETTER KOMI DE
  mCyrillicLatinConfusables.Insert(0x0435);  // е CYRILLIC SMALL LETTER IE
  mCyrillicLatinConfusables.Insert(0x050D);  // ԍ CYRILLIC SMALL LETTER KOMI SJE
  mCyrillicLatinConfusables.Insert(0x04BB);  // һ CYRILLIC SMALL LETTER SHHA
  mCyrillicLatinConfusables.Insert(
      0x0456);  // і CYRILLIC SMALL LETTER BYELORUSSIAN-UKRAINIAN I {Old
                // Cyrillic i}
  mCyrillicLatinConfusables.Insert(0x044E);  // ю CYRILLIC SMALL LETTER YU
  mCyrillicLatinConfusables.Insert(0x043A);  // к CYRILLIC SMALL LETTER KA
  mCyrillicLatinConfusables.Insert(0x0458);  // ј CYRILLIC SMALL LETTER JE
  mCyrillicLatinConfusables.Insert(0x04CF);  // ӏ CYRILLIC SMALL LETTER PALOCHKA
  mCyrillicLatinConfusables.Insert(0x043C);  // м CYRILLIC SMALL LETTER EM
  mCyrillicLatinConfusables.Insert(0x043E);  // о CYRILLIC SMALL LETTER O
  mCyrillicLatinConfusables.Insert(0x0440);  // р CYRILLIC SMALL LETTER ER
  mCyrillicLatinConfusables.Insert(
      0x0517);  // ԗ CYRILLIC SMALL LETTER RHA {voiceless r}
  mCyrillicLatinConfusables.Insert(0x051B);  // ԛ CYRILLIC SMALL LETTER QA
  mCyrillicLatinConfusables.Insert(0x0455);  // ѕ CYRILLIC SMALL LETTER DZE
  mCyrillicLatinConfusables.Insert(0x051D);  // ԝ CYRILLIC SMALL LETTER WE
  mCyrillicLatinConfusables.Insert(0x0445);  // х CYRILLIC SMALL LETTER HA
  mCyrillicLatinConfusables.Insert(0x0443);  // у CYRILLIC SMALL LETTER U
  mCyrillicLatinConfusables.Insert(
      0x044A);  // ъ CYRILLIC SMALL LETTER HARD SIGN
  mCyrillicLatinConfusables.Insert(
      0x044C);  // ь CYRILLIC SMALL LETTER SOFT SIGN
  mCyrillicLatinConfusables.Insert(
      0x04BD);  // ҽ CYRILLIC SMALL LETTER ABKHASIAN CHE
  mCyrillicLatinConfusables.Insert(0x043F);  // п CYRILLIC SMALL LETTER PE
  mCyrillicLatinConfusables.Insert(0x0433);  // г CYRILLIC SMALL LETTER GHE
  mCyrillicLatinConfusables.Insert(0x0475);  // ѵ CYRILLIC SMALL LETTER IZHITSA
  mCyrillicLatinConfusables.Insert(0x0461);  // ѡ CYRILLIC SMALL LETTER OMEGA
}

void nsIDNService::InitThaiLatinConfusables() {
  // Some of the Thai characters are only confusable on Linux.
#if defined(XP_LINUX) && !defined(ANDROID)
  mThaiLatinConfusables.Insert(0x0E14);  // ด
  mThaiLatinConfusables.Insert(0x0E17);  // ท
  mThaiLatinConfusables.Insert(0x0E19);  // น
  mThaiLatinConfusables.Insert(0x0E1B);  // ป
  mThaiLatinConfusables.Insert(0x0E21);  // ม
  mThaiLatinConfusables.Insert(0x0E25);  // ล
  mThaiLatinConfusables.Insert(0x0E2B);  // ห
#endif

  mThaiLatinConfusables.Insert(0x0E1A);  // บ
  mThaiLatinConfusables.Insert(0x0E1E);  // พ
  mThaiLatinConfusables.Insert(0x0E1F);  // ฟ
  mThaiLatinConfusables.Insert(0x0E23);  // ร
  mThaiLatinConfusables.Insert(0x0E40);  // เ
  mThaiLatinConfusables.Insert(0x0E41);  // แ
  mThaiLatinConfusables.Insert(0x0E50);  // ๐
}

nsIDNService::nsIDNService() { MOZ_ASSERT(NS_IsMainThread()); }

nsIDNService::~nsIDNService() = default;

NS_IMETHODIMP nsIDNService::DomainToASCII(const nsACString& input,
                                          nsACString& ace) {
  return NS_DomainToASCII(input, ace);
}

NS_IMETHODIMP nsIDNService::ConvertUTF8toACE(const nsACString& input,
                                             nsACString& ace) {
  return NS_DomainToASCIIAllowAnyGlyphfulASCII(input, ace);
}

NS_IMETHODIMP nsIDNService::ConvertACEtoUTF8(const nsACString& input,
                                             nsACString& _retval) {
  return NS_DomainToUnicodeAllowAnyGlyphfulASCII(input, _retval);
}

NS_IMETHODIMP nsIDNService::DomainToDisplay(const nsACString& input,
                                            nsACString& _retval) {
  nsresult rv = NS_DomainToDisplay(input, _retval);
  return rv;
}

NS_IMETHODIMP nsIDNService::ConvertToDisplayIDN(const nsACString& input,
                                                nsACString& _retval) {
  nsresult rv = NS_DomainToDisplayAllowAnyGlyphfulASCII(input, _retval);
  return rv;
}

//-----------------------------------------------------------------------------

namespace mozilla::net {

enum ScriptCombo : int32_t {
  UNSET = -1,
  BOPO = 0,
  CYRL = 1,
  GREK = 2,
  HANG = 3,
  HANI = 4,
  HIRA = 5,
  KATA = 6,
  LATN = 7,
  OTHR = 8,
  JPAN = 9,   // Latin + Han + Hiragana + Katakana
  CHNA = 10,  // Latin + Han + Bopomofo
  KORE = 11,  // Latin + Han + Hangul
  HNLT = 12,  // Latin + Han (could be any of the above combinations)
  FAIL = 13,
};

// Ignore - set if the label contains a character that makes it
// obvious it's not a lookalike.
// Safe - set if the label contains no lookalike characters.
// Block - set if the label contains lookalike characters.
enum class LookalikeStatus { Ignore, Safe, Block };

class MOZ_STACK_CLASS LookalikeStatusChecker {
 public:
  // Constructor for Script Confusable Checkers (Cyrillic, Thai, etc)
  LookalikeStatusChecker(nsTHashSet<char32_t>& aConfusables,
                         mozilla::Span<const char32_t>& aTLD, Script aTLDScript,
                         bool aValidTLD)
      : mConfusables(aConfusables),
        mStatus(aValidTLD ? LookalikeStatus::Ignore : LookalikeStatus::Safe),
        mTLDMatchesScript(doesTLDScriptMatch(aTLD, aTLDScript)),
        mTLDScript(aTLDScript) {}

  // Constructor that DigitLookalikeStatusChecker inherits
  explicit LookalikeStatusChecker(nsTHashSet<char32_t>& aConfusables)
      : mConfusables(aConfusables), mStatus(LookalikeStatus::Safe) {}

  // For the Script Confusable Checkers
  virtual void CheckCharacter(char32_t aChar, Script aScript) {
    if (mStatus != LookalikeStatus::Ignore && !mTLDMatchesScript &&
        aScript == mTLDScript) {
      mStatus = mConfusables.Contains(aChar) ? LookalikeStatus::Block
                                             : LookalikeStatus::Ignore;
    }
  }

  virtual LookalikeStatus Status() { return mStatus; }

 protected:
  // A hash set containing confusable characters
  nsTHashSet<char32_t>& mConfusables;

  // The current lookalike status
  LookalikeStatus mStatus;

  bool doesTLDScriptMatch(mozilla::Span<const char32_t>& aTLD, Script aScript) {
    mozilla::Span<const char32_t>::const_iterator current = aTLD.cbegin();
    mozilla::Span<const char32_t>::const_iterator end = aTLD.cend();

    while (current != end) {
      char32_t ch = *current++;
      if (UnicodeProperties::GetScriptCode(ch) == aScript) {
        return true;
      }
    }

    return false;
  }

 private:
  // Indicates whether the TLD matches the given script
  bool mTLDMatchesScript{false};

  // The script associated with the TLD to be matched
  Script mTLDScript{Script::INVALID};
};

// Overrides the CheckCharacter method to validate digits
class DigitLookalikeStatusChecker : public LookalikeStatusChecker {
 public:
  explicit DigitLookalikeStatusChecker(nsTHashSet<char32_t>& aConfusables)
      : LookalikeStatusChecker(aConfusables) {}

  // Note: aScript is not used in this override.
  void CheckCharacter(char32_t aChar, Script aScript) override {
    if (mStatus == LookalikeStatus::Ignore) {
      return;
    }

    // If the character is not a numeric digit, check whether it is confusable
    // or not.
    if (!ISDIGIT(aChar)) {
      mStatus = mConfusables.Contains(aChar) ? LookalikeStatus::Block
                                             : LookalikeStatus::Ignore;
    }
  }
};

}  // namespace mozilla::net

bool nsIDNService::IsLabelSafe(mozilla::Span<const char32_t> aLabel,
                               mozilla::Span<const char32_t> aTLD) {
  if (StaticPrefs::network_IDN_show_punycode()) {
    return false;
  }

  if (!isOnlySafeChars(aLabel, mIDNBlocklist)) {
    return false;
  }

  // Bug 1917119 - Avoid bypassing the doesTLDScriptMatch check
  // aTLD should be a decoded label, but in the case of invalid labels such as
  // `xn--xn--d--fg4n` we might end up with something that starts with `xn--`.
  // Treat those as unsafe just in case.
  if (TLDStartsWith(aTLD, "xn--")) {
    return false;
  }

  mozilla::Span<const char32_t>::const_iterator current = aLabel.cbegin();
  mozilla::Span<const char32_t>::const_iterator end = aLabel.cend();

  Script lastScript = Script::INVALID;
  char32_t previousChar = 0;
  char32_t baseChar = 0;  // last non-diacritic seen (base char for marks)
  char32_t savedNumberingSystem = 0;

  // Ignore digit confusables if there is a non-digit and non-digit confusable
  // character. If aLabel only consists of digits and digit confusables or
  // digit confusables, return false.
  DigitLookalikeStatusChecker digitStatusChecker(mDigitConfusables);
  // Check if all the cyrillic letters in the label are confusables
  LookalikeStatusChecker cyrillicStatusChecker(mCyrillicLatinConfusables, aTLD,
                                               Script::CYRILLIC,
                                               isCyrillicDomain(aTLD));
  // Check if all the Thai letters in the label are confusables
  LookalikeStatusChecker thaiStatusChecker(
      mThaiLatinConfusables, aTLD, Script::THAI, TLDEqualsLiteral(aTLD, "th"));

// Simplified/Traditional Chinese check temporarily disabled -- bug 857481
#if 0
  HanVariantType savedHanVariant = HVT_NotHan;
#endif

  ScriptCombo savedScript = ScriptCombo::UNSET;

  while (current != end) {
    char32_t ch = *current++;

    IdentifierType idType = GetIdentifierType(ch);
    if (idType == IDTYPE_RESTRICTED) {
      return false;
    }
    MOZ_ASSERT(idType == IDTYPE_ALLOWED);

    // Check for mixed script
    Script script = UnicodeProperties::GetScriptCode(ch);
    if (script != Script::COMMON && script != Script::INHERITED &&
        script != lastScript) {
      if (illegalScriptCombo(script, savedScript)) {
        return false;
      }
    }

#ifdef XP_MACOSX
    // U+0620, U+0f8c, U+0f8d, U+0f8e, U+0f8f and are blocked due to a font
    // issue on macOS
    if (ch == 0x620 || ch == 0xf8c || ch == 0xf8d || ch == 0xf8e ||
        ch == 0xf8f) {
      return false;
    }
#endif

    // U+30FC should be preceded by a Hiragana/Katakana.
    if (ch == 0x30fc && lastScript != Script::HIRAGANA &&
        lastScript != Script::KATAKANA) {
      return false;
    }

    Script nextScript = Script::INVALID;
    if (current != end) {
      nextScript = UnicodeProperties::GetScriptCode(*current);
    }

    // U+3078 to U+307A (へ, べ, ぺ) in Hiragana mixed with Katakana should be
    // unsafe
    if (ch >= 0x3078 && ch <= 0x307A &&
        (lastScript == Script::KATAKANA || nextScript == Script::KATAKANA)) {
      return false;
    }
    // U+30D8 to U+30DA (ヘ, ベ, ペ) in Katakana mixed with Hiragana should be
    // unsafe
    if (ch >= 0x30D8 && ch <= 0x30DA &&
        (lastScript == Script::HIRAGANA || nextScript == Script::HIRAGANA)) {
      return false;
    }
    // U+30FD and U+30FE are allowed only after Katakana
    if ((ch == 0x30FD || ch == 0x30FE) && lastScript != Script::KATAKANA) {
      return false;
    }

    // Slash confusables not enclosed by {Han,Hiragana,Katakana} should be
    // unsafe but by itself should be allowed.
    if (isCJKSlashConfusable(ch) && aLabel.Length() > 1 &&
        lastScript != Script::HAN && lastScript != Script::HIRAGANA &&
        lastScript != Script::KATAKANA && nextScript != Script::HAN &&
        nextScript != Script::HIRAGANA && nextScript != Script::KATAKANA) {
      return false;
    }

    if (ch == 0x30FB &&
        (lastScript == Script::LATIN || nextScript == Script::LATIN)) {
      return false;
    }

    // Combining Diacritic marks (U+0300-U+0339) after a script other than
    // Latin-Greek-Cyrillic is unsafe
    if (ch >= 0x300 && ch <= 0x339 && lastScript != Script::LATIN &&
        lastScript != Script::GREEK && lastScript != Script::CYRILLIC) {
      return false;
    }

    if (ch == 0x307 &&
        (previousChar == 'i' || previousChar == 'j' || previousChar == 'l')) {
      return false;
    }

    // U+00B7 is only allowed on Catalan domains between two l's.
    if (ch == 0xB7 && (!TLDEqualsLiteral(aTLD, "cat") || previousChar != 'l' ||
                       current == end || *current != 'l')) {
      return false;
    }

    // Disallow Icelandic confusables for domains outside Icelandic and Faroese
    // ccTLD (.is, .fo)
    if ((ch == 0xFE || ch == 0xF0) && !TLDEqualsLiteral(aTLD, "is") &&
        !TLDEqualsLiteral(aTLD, "fo")) {
      return false;
    }

    // Disallow U+0259 for domains outside Azerbaijani ccTLD (.az)
    if (ch == 0x259 && !TLDEqualsLiteral(aTLD, "az")) {
      return false;
    }

    // Block single/double-quote-like characters.
    if (ch == 0x2BB || ch == 0x2BC) {
      return false;
    }

    // Update the status based on whether the current character is a confusable
    // or not and determine if it should be blocked or ignored.
    // Note: script is not used for digitStatusChecker
    digitStatusChecker.CheckCharacter(ch, script);
    cyrillicStatusChecker.CheckCharacter(ch, script);
    thaiStatusChecker.CheckCharacter(ch, script);

    // Block these CJK ideographs if they are adjacent to non-CJK characters.
    // These characters can be used to spoof Latin characters/punctuation marks.
    if (isCJKIdeograph(ch)) {
      // Check if there is a non-Bopomofo, non-Hiragana, non-Katakana, non-Han,
      // and non-Numeric character on the left. previousChar is 0 when ch is the
      // first character.
      if (lastScript != Script::BOPOMOFO && lastScript != Script::HIRAGANA &&
          lastScript != Script::KATAKANA && lastScript != Script::HAN &&
          previousChar && !ISDIGIT(previousChar)) {
        return false;
      }
      // Check if there is a non-Bopomofo, non-Hiragana, non-Katakana, non-Han,
      // and non-Numeric character on the right.
      if (nextScript != Script::BOPOMOFO && nextScript != Script::HIRAGANA &&
          nextScript != Script::KATAKANA && nextScript != Script::HAN &&
          current != aLabel.end() && !ISDIGIT(*current)) {
        return false;
      }
    }

    // Check for mixed numbering systems
    auto genCat = GetGeneralCategory(ch);
    if (genCat == HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER) {
      uint32_t zeroCharacter =
          ch - mozilla::intl::UnicodeProperties::GetNumericValue(ch);
      if (savedNumberingSystem == 0) {
        // If we encounter a decimal number, save the zero character from that
        // numbering system.
        savedNumberingSystem = zeroCharacter;
      } else if (zeroCharacter != savedNumberingSystem) {
        return false;
      }
    }

    if (genCat == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {
      // Check for consecutive non-spacing marks.
      if (previousChar != 0 && previousChar == ch) {
        return false;
      }
      // Check for marks whose expected script doesn't match the base script.
      if (lastScript != Script::INVALID) {
        UnicodeProperties::ScriptExtensionVector scripts;
        auto extResult = UnicodeProperties::GetExtensions(ch, scripts);
        MOZ_ASSERT(extResult.isOk());
        if (extResult.isErr()) {
          return false;
        }

        int nScripts = AssertedCast<int>(scripts.length());

        // nScripts will always be >= 1, because even for undefined characters
        // it will return Script::INVALID.
        // If the mark just has script=COMMON or INHERITED, we can't check any
        // more carefully, but if it has specific scriptExtension codes, then
        // assume those are the only valid scripts to use it with.
        if (nScripts > 1 || (Script(scripts[0]) != Script::COMMON &&
                             Script(scripts[0]) != Script::INHERITED)) {
          while (--nScripts >= 0) {
            if (Script(scripts[nScripts]) == lastScript) {
              break;
            }
          }
          if (nScripts == -1) {
            return false;
          }
        }
      }
      // Check for diacritics on dotless-i, which would be indistinguishable
      // from normal accented letter i.
      if (baseChar == 0x0131 &&
          ((ch >= 0x0300 && ch <= 0x0314) || ch == 0x031a)) {
        return false;
      }
    } else {
      baseChar = ch;
    }

    if (script != Script::COMMON && script != Script::INHERITED) {
      lastScript = script;
    }

    // Simplified/Traditional Chinese check temporarily disabled -- bug 857481
#if 0

    // Check for both simplified-only and traditional-only Chinese characters
    HanVariantType hanVariant = GetHanVariant(ch);
    if (hanVariant == HVT_SimplifiedOnly || hanVariant == HVT_TraditionalOnly) {
      if (savedHanVariant == HVT_NotHan) {
        savedHanVariant = hanVariant;
      } else if (hanVariant != savedHanVariant)  {
        return false;
      }
    }
#endif

    previousChar = ch;
  }
  return digitStatusChecker.Status() != LookalikeStatus::Block &&
         (!StaticPrefs::network_idn_punycode_cyrillic_confusables() ||
          cyrillicStatusChecker.Status() != LookalikeStatus::Block) &&
         thaiStatusChecker.Status() != LookalikeStatus::Block;
}

// Scripts that we care about in illegalScriptCombo
static inline ScriptCombo findScriptIndex(Script aScript) {
  switch (aScript) {
    case Script::BOPOMOFO:
      return ScriptCombo::BOPO;
    case Script::CYRILLIC:
      return ScriptCombo::CYRL;
    case Script::GREEK:
      return ScriptCombo::GREK;
    case Script::HANGUL:
      return ScriptCombo::HANG;
    case Script::HAN:
      return ScriptCombo::HANI;
    case Script::HIRAGANA:
      return ScriptCombo::HIRA;
    case Script::KATAKANA:
      return ScriptCombo::KATA;
    case Script::LATIN:
      return ScriptCombo::LATN;
    default:
      return ScriptCombo::OTHR;
  }
}

static const ScriptCombo scriptComboTable[13][9] = {
    /* thisScript: BOPO  CYRL  GREK  HANG  HANI  HIRA  KATA  LATN  OTHR
     * savedScript */
    /* BOPO */ {BOPO, FAIL, FAIL, FAIL, CHNA, FAIL, FAIL, CHNA, FAIL},
    /* CYRL */ {FAIL, CYRL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL},
    /* GREK */ {FAIL, FAIL, GREK, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL},
    /* HANG */ {FAIL, FAIL, FAIL, HANG, KORE, FAIL, FAIL, KORE, FAIL},
    /* HANI */ {CHNA, FAIL, FAIL, KORE, HANI, JPAN, JPAN, HNLT, FAIL},
    /* HIRA */ {FAIL, FAIL, FAIL, FAIL, JPAN, HIRA, JPAN, JPAN, FAIL},
    /* KATA */ {FAIL, FAIL, FAIL, FAIL, JPAN, JPAN, KATA, JPAN, FAIL},
    /* LATN */ {CHNA, FAIL, FAIL, KORE, HNLT, JPAN, JPAN, LATN, OTHR},
    /* OTHR */ {FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, OTHR, FAIL},
    /* JPAN */ {FAIL, FAIL, FAIL, FAIL, JPAN, JPAN, JPAN, JPAN, FAIL},
    /* CHNA */ {CHNA, FAIL, FAIL, FAIL, CHNA, FAIL, FAIL, CHNA, FAIL},
    /* KORE */ {FAIL, FAIL, FAIL, KORE, KORE, FAIL, FAIL, KORE, FAIL},
    /* HNLT */ {CHNA, FAIL, FAIL, KORE, HNLT, JPAN, JPAN, HNLT, FAIL}};

bool nsIDNService::illegalScriptCombo(Script script, ScriptCombo& savedScript) {
  if (savedScript == ScriptCombo::UNSET) {
    savedScript = findScriptIndex(script);
    return false;
  }

  savedScript = scriptComboTable[savedScript][findScriptIndex(script)];

  return savedScript == OTHR || savedScript == FAIL;
}

extern "C" MOZ_EXPORT bool mozilla_net_is_label_safe(const char32_t* aLabel,
                                                     size_t aLabelLen,
                                                     const char32_t* aTld,
                                                     size_t aTldLen) {
  return static_cast<nsIDNService*>(nsStandardURL::GetIDNService())
      ->IsLabelSafe(mozilla::Span<const char32_t>(aLabel, aLabelLen),
                    mozilla::Span<const char32_t>(aTld, aTldLen));
}

bool nsIDNService::isCJKSlashConfusable(char32_t aChar) {
  return mCJKSlashConfusables.Contains(aChar);
}

bool nsIDNService::isCJKIdeograph(char32_t aChar) {
  return mCJKIdeographs.Contains(aChar);
}