DomainValidator.pas

(*
   Copyright 2013 - Leonardo Herrera (leonardo.herrera@gmail.com)

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*)
unit DomainValidator;

interface

uses RegularExpressions, Generics.Collections;

// Regular expression strings for hostnames (derived from RFC2396 and RFC 1123)
const
  DOMAIN_LABEL_REGEX = '[[:alnum:]](?>[[:alnum:]-]*[[:alnum:]])*';
  TOP_LABEL_REGEX = '[[:alnum:]]{2,}';
  DOMAIN_NAME_REGEX = '^(?:' + DOMAIN_LABEL_REGEX + '\.)+' + '(' +
    TOP_LABEL_REGEX + ')$';

type

  TDomainValidator = class
  private
    allowLocal: boolean;
    domainRegex, hostnameRegex: TRegEx;
    function chompLeadingDot(str: String): String;
  public
    function isValid(domain: String): boolean;
    function isValidTld(tld: String): boolean;
    function isValidInfrastructureTld(iTld: String): boolean;
    function isValidLocalTld(iTld: String): boolean;
    function isValidGenericTld(gTld: String): boolean;
    function isValidCountryCodeTld(ccTld: String): boolean;
    constructor Create(allowLocal: boolean = false);
  end;

var
  INFRASTRUCTURE_TLD_LIST, GENERIC_TLD_LIST, COUNTRY_CODE_TLD_LIST,
    LOCAL_TLD_LIST: TList<String>;

implementation

uses SysUtils, StrUtils;

{ TDomainValidator }

function TDomainValidator.chompLeadingDot(str: String): String;
begin
  if AnsiStartsStr('.', str) then
    Result := Copy(str, 1, Length(str) - 1)
  else
    Result := str;
end;

constructor TDomainValidator.Create(allowLocal: boolean);
begin
  Self.allowLocal := allowLocal;
  domainRegex := TRegEx.Create(DOMAIN_NAME_REGEX, [roCompiled]);
  hostnameRegex := TRegEx.Create(DOMAIN_LABEL_REGEX, [roCompiled]);
end;

function TDomainValidator.isValid(domain: String): boolean;
var
  Match: TMatch;
begin
  Result := false;
  Match := domainRegex.Match(domain);
  if Match.Success and (Match.Groups.Count > 0) then
    Result := isValidTld(Match.Groups[1].Value)
  else
  begin
    if allowLocal then
      Result := hostnameRegex.IsMatch(domain);
  end;
end;

function TDomainValidator.isValidCountryCodeTld(ccTld: String): boolean;
begin
  Result := COUNTRY_CODE_TLD_LIST.contains
    (chompLeadingDot(AnsiLowerCase(ccTld)));
end;

function TDomainValidator.isValidGenericTld(gTld: String): boolean;
begin
  Result := GENERIC_TLD_LIST.contains(chompLeadingDot(AnsiLowerCase(gTld)));
end;

function TDomainValidator.isValidInfrastructureTld(iTld: String): boolean;
begin
  Result := INFRASTRUCTURE_TLD_LIST.contains
    (chompLeadingDot(AnsiLowerCase(iTld)));

end;

function TDomainValidator.isValidLocalTld(iTld: String): boolean;
begin
  Result := LOCAL_TLD_LIST.contains(chompLeadingDot(AnsiLowerCase(iTld)));

end;

function TDomainValidator.isValidTld(tld: String): boolean;
begin
  if allowLocal and isValidLocalTld(tld) then
    Result := True
  else
    Result := isValidInfrastructureTld(tld) or isValidGenericTld(tld) or
      isValidCountryCodeTld(tld);
end;

initialization

INFRASTRUCTURE_TLD_LIST := TList<String>.Create;
INFRASTRUCTURE_TLD_LIST.AddRange(['arpa', // internet infrastructure
  'root' // diagnostic marker for non-truncated root zone
  ]);

GENERIC_TLD_LIST := TList<String>.Create;
GENERIC_TLD_LIST.AddRange(['aero', // air transport industry
  'asia', // Pan-Asia/Asia Pacific
  'biz', // businesses
  'cat', // Catalan linguistic/cultural community
  'com', // commercial enterprises
  'coop', // cooperative associations
  'info', // informational sites
  'jobs', // Human Resource managers
  'mobi', // mobile products and services
  'museum', // museums, surprisingly enough
  'name', // individuals' sites
  'net', // internet support infrastructure/business
  'org', // noncommercial organizations
  'pro', // credentialed professionals and entities
  'tel', // contact data for businesses and individuals
  'travel', // entities in the travel industry
  'gov', // United States Government
  'edu', // accredited postsecondary US education entities
  'mil', // United States Military
  'int' // organizations established by international treaty
  ]);

COUNTRY_CODE_TLD_LIST := TList<String>.Create;
COUNTRY_CODE_TLD_LIST.AddRange(['ac', // Ascension Island
  'ad', // Andorra
  'ae', // United Arab Emirates
  'af', // Afghanistan
  'ag', // Antigua and Barbuda
  'ai', // Anguilla
  'al', // Albania
  'am', // Armenia
  'an', // Netherlands Antilles
  'ao', // Angola
  'aq', // Antarctica
  'ar', // Argentina
  'as', // American Samoa
  'at', // Austria
  'au', // Australia (includes Ashmore and Cartier Islands and Coral Sea Islands)
  'aw', // Aruba
  'ax', // Ã?land
  'az', // Azerbaijan
  'ba', // Bosnia and Herzegovina
  'bb', // Barbados
  'bd', // Bangladesh
  'be', // Belgium
  'bf', // Burkina Faso
  'bg', // Bulgaria
  'bh', // Bahrain
  'bi', // Burundi
  'bj', // Benin
  'bm', // Bermuda
  'bn', // Brunei Darussalam
  'bo', // Bolivia
  'br', // Brazil
  'bs', // Bahamas
  'bt', // Bhutan
  'bv', // Bouvet Island
  'bw', // Botswana
  'by', // Belarus
  'bz', // Belize
  'ca', // Canada
  'cc', // Cocos (Keeling) Islands
  'cd', // Democratic Republic of the Congo (formerly Zaire)
  'cf', // Central African Republic
  'cg', // Republic of the Congo
  'ch', // Switzerland
  'ci', // Côte d'Ivoire
  'ck', // Cook Islands
  'cl', // Chile
  'cm', // Cameroon
  'cn', // China, mainland
  'co', // Colombia
  'cr', // Costa Rica
  'cu', // Cuba
  'cv', // Cape Verde
  'cx', // Christmas Island
  'cy', // Cyprus
  'cz', // Czech Republic
  'de', // Germany
  'dj', // Djibouti
  'dk', // Denmark
  'dm', // Dominica
  'do', // Dominican Republic
  'dz', // Algeria
  'ec', // Ecuador
  'ee', // Estonia
  'eg', // Egypt
  'er', // Eritrea
  'es', // Spain
  'et', // Ethiopia
  'eu', // European Union
  'fi', // Finland
  'fj', // Fiji
  'fk', // Falkland Islands
  'fm', // Federated States of Micronesia
  'fo', // Faroe Islands
  'fr', // France
  'ga', // Gabon
  'gb', // Great Britain (United Kingdom)
  'gd', // Grenada
  'ge', // Georgia
  'gf', // French Guiana
  'gg', // Guernsey
  'gh', // Ghana
  'gi', // Gibraltar
  'gl', // Greenland
  'gm', // The Gambia
  'gn', // Guinea
  'gp', // Guadeloupe
  'gq', // Equatorial Guinea
  'gr', // Greece
  'gs', // South Georgia and the South Sandwich Islands
  'gt', // Guatemala
  'gu', // Guam
  'gw', // Guinea-Bissau
  'gy', // Guyana
  'hk', // Hong Kong
  'hm', // Heard Island and McDonald Islands
  'hn', // Honduras
  'hr', // Croatia (Hrvatska)
  'ht', // Haiti
  'hu', // Hungary
  'id', // Indonesia
  'ie', // Ireland (Ã?ire)
  'il', // Israel
  'im', // Isle of Man
  'in', // India
  'io', // British Indian Ocean Territory
  'iq', // Iraq
  'ir', // Iran
  'is', // Iceland
  'it', // Italy
  'je', // Jersey
  'jm', // Jamaica
  'jo', // Jordan
  'jp', // Japan
  'ke', // Kenya
  'kg', // Kyrgyzstan
  'kh', // Cambodia (Khmer)
  'ki', // Kiribati
  'km', // Comoros
  'kn', // Saint Kitts and Nevis
  'kp', // North Korea
  'kr', // South Korea
  'kw', // Kuwait
  'ky', // Cayman Islands
  'kz', // Kazakhstan
  'la', // Laos (currently being marketed as the official domain for Los Angeles)
  'lb', // Lebanon
  'lc', // Saint Lucia
  'li', // Liechtenstein
  'lk', // Sri Lanka
  'lr', // Liberia
  'ls', // Lesotho
  'lt', // Lithuania
  'lu', // Luxembourg
  'lv', // Latvia
  'ly', // Libya
  'ma', // Morocco
  'mc', // Monaco
  'md', // Moldova
  'me', // Montenegro
  'mg', // Madagascar
  'mh', // Marshall Islands
  'mk', // Republic of Macedonia
  'ml', // Mali
  'mm', // Myanmar
  'mn', // Mongolia
  'mo', // Macau
  'mp', // Northern Mariana Islands
  'mq', // Martinique
  'mr', // Mauritania
  'ms', // Montserrat
  'mt', // Malta
  'mu', // Mauritius
  'mv', // Maldives
  'mw', // Malawi
  'mx', // Mexico
  'my', // Malaysia
  'mz', // Mozambique
  'na', // Namibia
  'nc', // New Caledonia
  'ne', // Niger
  'nf', // Norfolk Island
  'ng', // Nigeria
  'ni', // Nicaragua
  'nl', // Netherlands
  'no', // Norway
  'np', // Nepal
  'nr', // Nauru
  'nu', // Niue
  'nz', // New Zealand
  'om', // Oman
  'pa', // Panama
  'pe', // Peru
  'pf', // French Polynesia With Clipperton Island
  'pg', // Papua New Guinea
  'ph', // Philippines
  'pk', // Pakistan
  'pl', // Poland
  'pm', // Saint-Pierre and Miquelon
  'pn', // Pitcairn Islands
  'pr', // Puerto Rico
  'ps', // Palestinian territories (PA-controlled West Bank and Gaza Strip)
  'pt', // Portugal
  'pw', // Palau
  'py', // Paraguay
  'qa', // Qatar
  're', // Réunion
  'ro', // Romania
  'rs', // Serbia
  'ru', // Russia
  'rw', // Rwanda
  'sa', // Saudi Arabia
  'sb', // Solomon Islands
  'sc', // Seychelles
  'sd', // Sudan
  'se', // Sweden
  'sg', // Singapore
  'sh', // Saint Helena
  'si', // Slovenia
  'sj', // Svalbard and Jan Mayen Islands Not in use (Norwegian dependencies; see .no)
  'sk', // Slovakia
  'sl', // Sierra Leone
  'sm', // San Marino
  'sn', // Senegal
  'so', // Somalia
  'sr', // Suriname
  'st', // São Tomé and Príncipe
  'su', // Soviet Union (deprecated)
  'sv', // El Salvador
  'sy', // Syria
  'sz', // Swaziland
  'tc', // Turks and Caicos Islands
  'td', // Chad
  'tf', // French Southern and Antarctic Lands
  'tg', // Togo
  'th', // Thailand
  'tj', // Tajikistan
  'tk', // Tokelau
  'tl', // East Timor (deprecated old code)
  'tm', // Turkmenistan
  'tn', // Tunisia
  'to', // Tonga
  'tp', // East Timor
  'tr', // Turkey
  'tt', // Trinidad and Tobago
  'tv', // Tuvalu
  'tw', // Taiwan, Republic of China
  'tz', // Tanzania
  'ua', // Ukraine
  'ug', // Uganda
  'uk', // United Kingdom
  'um', // United States Minor Outlying Islands
  'us', // United States of America
  'uy', // Uruguay
  'uz', // Uzbekistan
  'va', // Vatican City State
  'vc', // Saint Vincent and the Grenadines
  've', // Venezuela
  'vg', // British Virgin Islands
  'vi', // U.S. Virgin Islands
  'vn', // Vietnam
  'vu', // Vanuatu
  'wf', // Wallis and Futuna
  'ws', // Samoa (formerly Western Samoa)
  'ye', // Yemen
  'yt', // Mayotte
  'yu', // Serbia and Montenegro (originally Yugoslavia)
  'za', // South Africa
  'zm', // Zambia
  'zw' // Zimbabwe
  ]);

LOCAL_TLD_LIST := TList<String>.Create;
LOCAL_TLD_LIST.AddRange(['localhost', // RFC2606 defined
  'localdomain' // Also widely used as localhost.localdomain
  ]);

end.