bool IsHTTPWhitespace(UChar chr) {
  return chr == ' ' || chr == '\n' || chr == '\t' || chr == '\r';
}

bool IsValidHTTPHeaderValue(const String& name) {
  // FIXME: This should really match name against
  // field-value in section 4.2 of RFC 2616.

  return name.ContainsOnlyLatin1OrEmpty() && !name.Contains('\r') &&
         !name.Contains('\n') && !name.Contains('\0');
}

template<Character CharacterType> constexpr bool isASCIIWhitespaceWithoutFF(CharacterType character)
{
    // This is different from isASCIIWhitespace: JSON/HTTP/XML do not accept \f as a whitespace.
    // ECMA-404 specifies the following:
    // > Whitespace is any sequence of one or more of the following code points:
    // > character tabulation (U+0009), line feed (U+000A), carriage return (U+000D), and space (U+0020).
    //
    // This matches HTTP whitespace:
    // https://fetch.spec.whatwg.org/#http-whitespace-byte
    //
    // And XML whitespace:
    // https://www.w3.org/TR/2008/REC-xml-20081126/#NT-S
    return character == ' ' || character == '\n' || character == '\t' || character == '\r';
}

bool isValidHTTPHeaderValue(const String& value)
{
    char16_t c = value[0];
    if (isTabOrSpace(c))
        return false;
    c = value[value.length() - 1];
    if (isTabOrSpace(c))
        return false;
    for (unsigned i = 0; i < value.length(); ++i) {
        c = value[i];
        if (c == 0x00 || c == 0x0A || c == 0x0D)
            return false;
    }
    return true;
}

void TrimHTTPWhitespace(const nsACString& aSource, nsACString& aDest) {
  nsAutoCString str(aSource);

  // HTTP whitespace 0x09: '\t', 0x0A: '\n', 0x0D: '\r', 0x20: ' '
  static const char kHTTPWhitespace[] = "\t\n\r ";
  str.Trim(kHTTPWhitespace);
  aDest.As

bool IsReasonableHeaderValue(const nsACString& s) {
  // Header values MUST NOT contain line-breaks.  RFC 2616 technically
  // permits CTL characters, including CR and LF, in header values provided
  // they are quoted.  However, this can lead to problems if servers do not
  // interpret quoted strings properly.  Disallowing CR and LF here seems
  // reasonable and keeps things simple.  We also disallow a null byte.
  const nsACString::char_type* end = s.EndReading();
  for (const nsACString::char_type* i = s.BeginReading(); i != end; ++i) {
    if (*i == '\r' || *i == '\n' || *i == '\0') {
      return false;
    }
  }
  return true;
}