Dart

Get OAuth2 Access Token for Azure Registered App

Demonstrates how to get OAuth2 access token for an Azure Registered App from a desktop application or script. This example demonstrates the OAuth2 authorization flow.

This example requires Chilkat v10.1.2 or greater.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // To further clarify, see OAuth 2.0 Authorization Flow

  final oauth2 = CkOAuth2();

  // This should be the port in the localhost callback URL for your app.  
  // The callback URL would look like "http://localhost:3017/" if the port number is 3017.
  oauth2.listenPort = 3017;

  // ----------------------------------------------------------------------------------------------------------
  // The screenshot at the bottom of this page shows how we created the Azure App Registration for this example.
  // ----------------------------------------------------------------------------------------------------------

  // Note: The endpoint depends on the Azure App Registration.
  // See How to Choose the Correct Endpoints for your Azure App Registration
  oauth2.authorizationEndpoint = 'https://login.microsoftonline.com/common/oauth2/v2.0/authorize';
  oauth2.tokenEndpoint = 'https://login.microsoftonline.com/common/oauth2/v2.0/token';

  // Replace these with actual values.
  oauth2.clientId = 'CLIENT_ID';

  // This is for Require Proof Key for Code Exchange (PKCE)
  // See OAuth2 PKCE Explained
  oauth2.codeChallenge = true;
  oauth2.codeChallengeMethod = 'S256';

  // Provide a SPACE separated list of scopes.
  // See https://developer.microsoft.com/en-us/graph/docs/authorization/permission_scopes 

  // Important: To get a refresh token in the final response, ask for "offline_access" scope
  oauth2.scope = 'openid profile offline_access user.readwrite mail.readwrite mail.send files.readwrite';

  // Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
  final String url;
  try {
    url = oauth2.startAuth();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Launch the default browser on the system and navigate to the url.
  // The LaunchBrowser method was added in Chilkat v10.1.2.
  try {
    oauth2.launchBrowser(url);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Wait for the user to approve or deny authorization in the browser.
  var numMsWaited = 0;
  while ((numMsWaited < 90000) && (oauth2.authFlowState < 3)) {
    oauth2.sleepMs(100);
    numMsWaited += 100;
  }

  // If the browser does not respond within the specified time, AuthFlowState will be:
  // 
  // 1: Waiting for Redirect � The OAuth2 background thread is waiting for the browser's redirect request.
  // 2: Waiting for Final Response � The thread is awaiting the final access token response.
  // In either case, cancel the background task initiated by StartAuth.

  if (oauth2.authFlowState < 3) {
    oauth2.cancel();
    print('No response from the browser!');
    return;
  }

  // Check AuthFlowState to determine if authorization was granted, denied, or failed:
  // 
  // 3: Success � OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
  // 4: Access Denied � OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
  // 5: Failure � OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

  if (oauth2.authFlowState == 5) {
    print('OAuth2 failed to complete.');
    print(oauth2.failureInfo);
    return;
  }

  if (oauth2.authFlowState == 4) {
    print('OAuth2 authorization was denied.');
    print(oauth2.accessTokenResponse);
    return;
  }

  if (oauth2.authFlowState != 3) {
    print('Unexpected AuthFlowState:${oauth2.authFlowState}');
    return;
  }

  print('OAuth2 authorization granted!');
  print('Access Token = ${oauth2.accessToken}');

  // When the token is near expiration, your app can refresh as shown here:
  // Refresh Expiring OAuth2 Access Token for Azure Registered App

  // Get the full JSON response:
  final json = CkJsonObject();
  json.load(oauth2.accessTokenResponse);
  json.emitCompact = false;

  // The JSON response looks like this:

  // {
  //   "token_type": "Bearer",
  //   "scope": "User.Read Mail.ReadWrite Mail.Send",
  //   "expires_in": 3600,
  //   "ext_expires_in": 0,
  //   "access_token": "EwBAA8l6B...",
  //   "refresh_token": "MCRMdbe...",
  //   "id_token": "eyJ0eXA..."
  // }

  // If an "expires_on" member does not exist, then add the JSON member by
  // getting the current system date/time and adding the "expires_in" seconds.
  // This way we'll know when the token expires.
  if (!json.hasMember('expires_on')) {
    final dtExpire = CkDateTime();
    dtExpire.setFromCurrentSystemTime();
    dtExpire.addSeconds(json.intOf('expires_in'));
    json.appendString('expires_on', dtExpire.getAsUnixTimeStr(false));
  }

  print(json.emit());

  // Save the JSON to a file for future requests.
  final fac = CkFileAccess();
  fac.writeEntireTextFile('qa_data/tokens/_myAzureApp.json', json.emit(), 'utf-8', false);

  // This is a screenshot of how we created the Azure App for this example:
  // 
}