Bring DNS lookup from basic_utils into this project

Release v1.0.2

.vscode/settings.json

@@ -1,5 +1,11 @@
 {
     "cSpell.words": [
-        "Imap"
+        "autoconfig",
+        "cupertino",
+        "dnssec",
+        "EMAILDOMAIN",
+        "Imap",
+        "rrecord",
+        "starttls"
     ]
 }

CHANGELOG.md

@@ -1,5 +1,9 @@
-## 1.0.1
+## 1.0.2
+* Fork DSN look-up from [basic_utils](https://github.com/Ephenodrom/Dart-Basic-Utils) into enough_mail_discovery to ensure full web-compatibility
+* Improve documentation
 
+
+## 1.0.1
 * Improve documentation
 * Add build dependency
 

example/example/lib/main.dart

@@ -99,8 +99,14 @@ class _MyHomePageState extends State<MyHomePage> {
                 ),
               if (config != null)
                 DiscoveredConfigViewer(config: config)
-              else if (_hasDiscovered)
+              else if (_hasDiscovered) ...[
+                const SizedBox(height: 16),
                 const Text('Unable to resolve settings...'),
+                const SizedBox(height: 8),
+                if (kIsWeb)
+                  const Text('Note that enough_mail_discovery can find more '
+                      'settings on non-web platforms')
+              ],
             ],
           ),
         ),
@@ -110,10 +116,12 @@ class _MyHomePageState extends State<MyHomePage> {
 
   bool _checkEmailAddressValidity() {
     final emailAddress = _editingController.text;
+    final atIndex = emailAddress.indexOf('@');
+    final lastDotIndex = emailAddress.lastIndexOf('.');
     return emailAddress.length > 5 &&
-        emailAddress.indexOf('@') > 1 &&
-        emailAddress.contains('.') &&
-        emailAddress.lastIndexOf('.') < emailAddress.length - 2;
+        atIndex > 1 &&
+        lastDotIndex > atIndex + 1 &&
+        lastDotIndex < emailAddress.length - 2;
   }
 
   Future<void> _discover() async {
@@ -125,6 +133,7 @@ class _MyHomePageState extends State<MyHomePage> {
     final emailAddress = _editingController.text;
     final result = await Discover.discover(
       emailAddress,
+      isLogEnabled: true,
       forceSslConnection: _forceSslConnection,
       isWeb: kIsWeb,
     );

lib/enough_mail_discovery.dart

@@ -1,4 +1,4 @@
 library enough_mail_discovery;
 
-export 'src/discover.dart';
 export 'src/client_config.dart';
+export 'src/discover.dart';

lib/src/discover.dart

@@ -1,6 +1,5 @@
-import 'discover_helper.dart';
-
 import 'client_config.dart';
+import 'discover_helper.dart';
 
 /// Helps discovering email connection settings based on an email address.
 ///

lib/src/discover_helper.dart

@@ -1,12 +1,13 @@
 import 'dart:async';
 
-import 'package:basic_utils/basic_utils.dart' as basic;
 import 'package:collection/collection.dart' show IterableExtension;
+import 'package:http/http.dart' as http;
 import 'package:universal_io/io.dart';
 import 'package:xml/xml.dart' as xml;
-import 'package:http/http.dart' as http;
 
 import 'client_config.dart';
+import 'dns/dns_utils.dart';
+import 'dns/rrecord_type.dart';
 
 /// Low-level helper methods for mail scenarios
 class DiscoverHelper {
@@ -70,8 +71,7 @@ class DiscoverHelper {
 
   /// Looks up domain referenced by the domain's DNS MX record
   static Future<String?> discoverMxDomain(String domain) async {
-    final mxRecords =
-        await basic.DnsUtils.lookupRecord(domain, basic.RRecordType.MX);
+    final mxRecords = await DnsUtils.lookupRecord(domain, RRecordType.MX);
     if (mxRecords == null || mxRecords.isEmpty) {
       //print('unable to read MX records for [$domain].');
       return null;

lib/src/dns/dns_utils.dart

@@ -0,0 +1,174 @@
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:http/http.dart' as http;
+
+import 'resolve_response.dart';
+import 'rrecord.dart';
+import 'rrecord_type.dart';
+
+/// Supported DNS API providers
+enum DnsApiProvider {
+  /// https://dns.google.com/resolve
+  google,
+
+  ///https://cloudflare-dns.com/dns-query
+  cloudflare,
+}
+
+/// Helper class for dns record lookups
+///
+/// Migrated from https://github.com/Ephenodrom/Dart-Basic-Utils to
+/// ensure compatibility with Flutter web.
+class DnsUtils {
+  DnsUtils._();
+
+  /// Base url for each dns resolver
+  ///
+  static const _dnsApiProviderUrl = {
+    DnsApiProvider.google: 'https://dns.google.com/resolve',
+    DnsApiProvider.cloudflare: 'https://cloudflare-dns.com/dns-query',
+  };
+
+  /// Lookup for records of the given [type] and [name].
+  /// It also supports [dnssec]
+  ///
+  static Future<List<RRecord>?> lookupRecord(
+    String name,
+    RRecordType type, {
+    bool dnssec = false,
+    DnsApiProvider provider = DnsApiProvider.google,
+  }) async {
+    final url = _dnsApiProviderUrl[provider]!;
+    final uri = Uri.parse(
+        '$url?name=$name&type=${_getTypeFromType(type)}&dnssec=$dnssec');
+
+    final headers = {'Accept': 'application/dns-json'};
+
+    final httpResponse = await http.get(uri, headers: headers);
+    final response = ResolveResponse.fromJson(jsonDecode(httpResponse.body));
+    return response.answer;
+  }
+
+  static String _getTypeFromType(RRecordType type) =>
+      rRecordTypeToInt(type).toString();
+
+  ///
+  /// Converts the given number [type] to a [RRecordType] enum.
+  ///
+  static RRecordType intToRRecordType(int type) =>
+      _intToRRecordType[type] ?? RRecordType.A;
+
+  ///
+  /// Converts the given type to a decimal number
+  ///
+  static int rRecordTypeToInt(RRecordType type) => _rRecordTypeToInt[type] ?? 1;
+
+  ///
+  /// Map from [RRecordType] enum to number
+  ///
+  static const _rRecordTypeToInt = {
+    RRecordType.A: 1,
+    RRecordType.AAAA: 28,
+    RRecordType.ANY: 255,
+    RRecordType.CAA: 257,
+    RRecordType.CDS: 59,
+    RRecordType.CERT: 37,
+    RRecordType.CNAME: 5,
+    RRecordType.DNAME: 39,
+    RRecordType.DNSKEY: 48,
+    RRecordType.DS: 43,
+    RRecordType.HINFO: 13,
+    RRecordType.IPSECKEY: 45,
+    RRecordType.MX: 15,
+    RRecordType.NAPTR: 35,
+    RRecordType.NS: 2,
+    RRecordType.NSEC: 47,
+    RRecordType.NSEC3PARAM: 51,
+    RRecordType.PTR: 12,
+    RRecordType.RP: 17,
+    RRecordType.RRSIG: 46,
+    RRecordType.SOA: 6,
+    RRecordType.SPF: 99,
+    RRecordType.SRV: 33,
+    RRecordType.SSHFP: 44,
+    RRecordType.TLSA: 52,
+    RRecordType.TXT: 16,
+    RRecordType.WKS: 11,
+  };
+
+  ///
+  /// Map from number to [RRecordType] enum
+  ///
+  static final _intToRRecordType =
+      _rRecordTypeToInt.map((k, v) => MapEntry(v, k));
+
+  /// Reverse lookup for the given [ip] to determine a hostname.
+  ///
+  /// This reverses the given [ip], adds ".in-addr.arpa" / ".ip6.arpa" and
+  /// tries to fetch a PTR record for the generated name.
+  ///
+  /// Will return null, if no IP address is given or no PTR is found.
+  ///
+  static Future<List<RRecord>?> reverseDns(
+    String ip, {
+    DnsApiProvider provider = DnsApiProvider.google,
+  }) async {
+    final reverse = getReverseAddr(ip);
+    if (reverse == null) {
+      return null;
+    }
+
+    final url = _dnsApiProviderUrl[provider];
+    final uri = Uri.parse(
+        '$url?name=$reverse&type=${_getTypeFromType(RRecordType.PTR)}');
+    final headers = {'Accept': 'application/dns-json'};
+
+    final httpResponse = await http.get(uri, headers: headers);
+    final response = ResolveResponse.fromJson(jsonDecode(httpResponse.body));
+    return response.answer;
+  }
+
+  ///
+  /// Reverses the given [ip] address. Will return null if the given [ip] is not
+  /// an IP address.
+  ///
+  /// Example :
+  /// 172.217.22.14 => 14.22.217.172.in-addr.arpa
+  /// 2a00:1450:4001:81a::200e => e.0.0.2.a.1.8.1.0.0.4.0.5.4.1.0.0.a.2.ip6.arpa
+  ///
+  static String? getReverseAddr(String ip) {
+    if (ip.contains('.')) {
+      return '${ip.split('.').reversed.join('.')}.in-addr.arpa';
+    } else if (ip.contains(':')) {
+      return '${ip.split(':').join().split('').reversed.join('.')}.ip6.arpa';
+    } else {
+      return null;
+    }
+  }
+
+  ///
+  /// Converts the record to the BIND representation.
+  ///
+  static String toBind(RRecord record) {
+    final sb = StringBuffer()..write(record.name);
+    if (sb.length < 8) {
+      sb.write('\t');
+    }
+    if (sb.length < 16) {
+      sb.write('\t');
+    }
+    sb
+      ..write('\t')
+      ..write(record.ttl)
+      ..write('\tIN\t')
+      ..write(intToRRecordType(record.rType)
+          .toString()
+          .substring('RRecordType.'.length))
+      ..write('\t')
+      ..write('\"')
+      ..write(record.data)
+      ..write('\"');
+    return sb.toString();
+  }
+}

lib/src/dns/question.dart

@@ -0,0 +1,25 @@
+// ignore_for_file: public_member_api_docs
+
+import 'package:json_annotation/json_annotation.dart';
+
+part 'question.g.dart';
+
+@JsonSerializable(includeIfNull: false)
+class Question {
+  const Question({required this.name, required this.type});
+
+  /*
+   * Json to Question object
+   */
+  factory Question.fromJson(Map<String, dynamic> json) =>
+      _$QuestionFromJson(json);
+
+  final String name;
+
+  final int type;
+
+  /*
+   * Question object to json
+   */
+  Map<String, dynamic> toJson() => _$QuestionToJson(this);
+}

lib/src/dns/resolve_response.dart

@@ -0,0 +1,51 @@
+// ignore_for_file: public_member_api_docs
+
+import 'package:json_annotation/json_annotation.dart';
+
+import 'question.dart';
+import 'rrecord.dart';
+
+part 'resolve_response.g.dart';
+
+@JsonSerializable(includeIfNull: false)
+class ResolveResponse {
+  const ResolveResponse({
+    this.status,
+    this.tc,
+    this.rd,
+    this.ra,
+    this.ad,
+    this.cd,
+    this.question,
+    this.answer,
+    this.comment,
+  });
+
+  /// Create [ResolveResponse] from [json]
+  factory ResolveResponse.fromJson(Map<String, dynamic> json) =>
+      _$ResolveResponseFromJson(json);
+
+  @JsonKey(name: 'Status')
+  final int? status;
+  @JsonKey(name: 'TC')
+  final bool? tc;
+  @JsonKey(name: 'RD')
+  final bool? rd;
+  @JsonKey(name: 'RA')
+  final bool? ra;
+  @JsonKey(name: 'AD')
+  final bool? ad;
+  @JsonKey(name: 'CD')
+  final bool? cd;
+  @JsonKey(name: 'Question')
+  final List<Question>? question;
+  @JsonKey(name: 'Answer')
+  final List<RRecord>? answer;
+  @JsonKey(name: 'Comment')
+  final String? comment;
+
+  /*
+   * ResolveResponse object to json
+   */
+  Map<String, dynamic> toJson() => _$ResolveResponseToJson(this);
+}