Google 和 Microsoft OAuth2 登录流程 Flutter Desktop（MacOS、Windows、Linux）

Question

如何在 Flutter Desktop 上实现 Google OAuth2 或 Microsoft (Azure) OAuth2 登录？

Answer 1

回答我自己的问题。获取 OAuth2 结果的总体流程是：

1. 您必须让桌面应用程序托管本地服务器，并将 OAuth 服务重定向到http://localhost:#####/dart 应用程序正在侦听的服务器。
2. 启动 URL 以使用oauth2在浏览器中启动 OAuth2 流程
3. 第一次返回服务器时，使用oauth2处理 OAuth2 响应

设置您想要支持的 OAuth 流。这是我用的：

1. Go to google admin or azure dashboard,
2. create a new app + add in Authorized redirect URIs the localhost url: http://localhost/
3. Copy the generated clientId and clientSecret into the configuration below:

enum LoginProvider { google, azure }

extension LoginProviderExtension on LoginProvider {
  String get key {
    switch (this) {
      case LoginProvider.google:
        return 'google';
      case LoginProvider.azure:
        return 'azure';
    }
  }

  String get authorizationEndpoint {
    switch (this) {
      case LoginProvider.google:
        return "https://accounts.google.com/o/oauth2/v2/auth";
      case LoginProvider.azure:
        return "https://login.microsoftonline.com/common/oauth2/v2.0/authorize";
    }
  }

  String get tokenEndpoint {
    switch (this) {
      case LoginProvider.google:
        return "https://oauth2.googleapis.com/token";
      case LoginProvider.azure:
        return "https://login.microsoftonline.com/common/oauth2/v2.0/token";
    }
  }

  String get clientId {
    switch (this) {
      case LoginProvider.google:
        return "GOOGLE_CLIENT_ID";
      case LoginProvider.azure:
        return "AZURE_CLIENT_ID";
    }
  }

  String? get clientSecret {
    switch (this) {
      case LoginProvider.google:
        return "GOOGLE_SECRET"; // if applicable
      case LoginProvider.azure:
        return "AZURE_SECRET"; // if applicable
    }
  }

  List<String> get scopes {
    return ['openid', 'email']; // OAuth Scopes
  }
}

Setup the OAuth Manager to create listen for the oauth2 redirect

import 'dart:async';
import 'dart:io';

import 'package:http/http.dart' as http;
import 'package:oauth2/oauth2.dart' as oauth2;
import 'package:url_launcher/url_launcher.dart';
import 'package:window_to_front/window_to_front.dart';

class DesktopLoginManager {
  HttpServer? redirectServer;
  oauth2.Client? client;

  // Launch the URL in the browser using url_launcher
  Future<void> redirect(Uri authorizationUrl) async {
    var url = authorizationUrl.toString();
    if (await canLaunch(url)) {
      await launch(url);
    } else {
      throw Exception('Could not launch $url');
    }
  }

  Future<Map<String, String>> listen() async {
    var request = await redirectServer!.first;
    var params = request.uri.queryParameters;
    await WindowToFront.activate(); // Using window_to_front package to bring the window to the front after successful login.  
    request.response.statusCode = 200;
    request.response.headers.set('content-type', 'text/plain');
    request.response.writeln('Authenticated! You can close this tab.');
    await request.response.close();
    await redirectServer!.close();
    redirectServer = null;
    return params;
  }
}

class DesktopOAuthManager extends DesktopLoginManager {
  final LoginProvider loginProvider;

  DesktopOAuthManager({
    required this.loginProvider,
  }) : super();

  void login() async {
    await redirectServer?.close();
    // Bind to an ephemeral port on localhost
    redirectServer = await HttpServer.bind('localhost', 0);
    final redirectURL = 'http://localhost:${redirectServer!.port}/auth';
    var authenticatedHttpClient =
        await _getOAuth2Client(Uri.parse(redirectURL));
    print("CREDENTIALS ${authenticatedHttpClient.credentials}");
    /// HANDLE SUCCESSFULL LOGIN RESPONSE HERE
    return;
  }

  Future<oauth2.Client> _getOAuth2Client(Uri redirectUrl) async {
    var grant = oauth2.AuthorizationCodeGrant(
      loginProvider.clientId,
      Uri.parse(loginProvider.authorizationEndpoint),
      Uri.parse(loginProvider.tokenEndpoint),
      httpClient: _JsonAcceptingHttpClient(),
      secret: loginProvider.clientSecret,
    );
    var authorizationUrl =
        grant.getAuthorizationUrl(redirectUrl, scopes: loginProvider.scopes);

    await redirect(authorizationUrl);
    var responseQueryParameters = await listen();
    var client =
        await grant.handleAuthorizationResponse(responseQueryParameters);
    return client;
  }
}

class _JsonAcceptingHttpClient extends http.BaseClient {
  final _httpClient = http.Client();
  @override
  Future<http.StreamedResponse> send(http.BaseRequest request) {
    request.headers['Accept'] = 'application/json';
    return _httpClient.send(request);
  }
}

Begin the login flow using

GOOGLE:

if (Platform.isMacOS || Platform.isWindows || Platform.isLinux) {
   final provider = DesktopOAuthManager(loginProvider: LoginProvider.google);
   provider.login();
}

AZURE:

if (Platform.isMacOS || Platform.isWindows || Platform.isLinux) {
   final provider = DesktopOAuthManager(loginProvider: LoginProvider. azure);
   provider.login();
}

You're done!