(PHP Extension) OAuth2 for a GMail using a JSON Service Account Key

Demonstrates how get an OAuth2 access token for GMail (Google Service Account) using a JSON private key.

After the access token is obtained, it may be used to send email. When the access token expires, a new access token needs to be obtained (using this same procedure).

Note: This is for OAuth2 using Google Service account keys.

Chilkat PHP Downloads PHP Extension for Windows, Linux, MacOS, Alpine Linux, Solaris

<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// First load the JSON key into a string.
$fac = new CkFileAccess();
$jsonKey = $fac->readEntireTextFile('qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json','utf-8');
if ($fac->get_LastMethodSuccess() != true) {
    print $fac->lastErrorText() . "\n";
    exit;
}

// A JSON private key should look like this:

// 	{
// 	  "type": "service_account",
// 	  "project_id": "chilkattest-1350",
// 	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
// 	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
// 	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
// 	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
// 	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
// 	  "token_uri": "https://accounts.google.com/o/oauth2/token",
// 	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
// 	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
// 	}

$gAuth = new CkAuthGoogle();
$gAuth->put_JsonKey($jsonKey);

// Choose a scope.
$gAuth->put_Scope('https://mail.google.com/');

// Request an access token that is valid for this many seconds.
$gAuth->put_ExpireNumSeconds(3600);

// If the application is requesting delegated access:
// The email address of the user for which the application is requesting delegated access,
// then set the email address here. (Otherwise leave it empty.)
$gAuth->put_SubEmailAddress('');

// Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
// The Chilkat socket object is used so that the connection can be established
// through proxies or an SSH tunnel if desired.
$tlsSock = new CkSocket();
$success = $tlsSock->Connect('www.googleapis.com',443,true,5000);
if ($success != true) {
    print $tlsSock->lastErrorText() . "\n";
    exit;
}

// Send the request to obtain the access token.
$success = $gAuth->ObtainAccessToken($tlsSock);
if ($success != true) {
    print $gAuth->lastErrorText() . "\n";
    exit;
}

// Examine the access token:
print 'Access Token: ' . $gAuth->accessToken() . "\n";

// Now that we have the access token, it may be used to send email
// while it remains valid.  Once the access token expires, a new access token 
// should be obtained using the same code as above.

// -----------------------------------------------------------------------
$mailman = new CkMailMan();

// Set the properties for the GMail SMTP server:
$mailman->put_SmtpHost('smtp.gmail.com');
$mailman->put_SmtpPort(587);
$mailman->put_StartTLS(true);

$mailman->put_SmtpUsername('YOUR_GOOGLE_APPS_USER_EMAIL_ADDRESS');
$mailman->put_OAuth2AccessToken($gAuth->accessToken());

// Create a new email object
$email = new CkEmail();

$email->put_Subject('This is a test');
$email->put_Body('This is a test');
$email->put_From('YOUR NAME <YOUR_GOOGLE_APPS_USER_EMAIL_ADDRESS>');
$success = $email->AddTo('Chilkat Admin','admin@chilkatsoft.com');
// To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

// Call SendEmail to connect to the SMTP server and send.
// The connection (i.e. session) to the SMTP server remains
// open so that subsequent SendEmail calls may use the
// same connection.  
$success = $mailman->SendEmail($email);
if ($success != true) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

// You may close the connection here.  If the connection is kept open, 
// the next call to mailman.SendEmail will continue using the already-established connection
// (and automatically re-connect if needed).
$success = $mailman->CloseSmtpConnection();
if ($success != true) {
    print 'Connection to SMTP server not closed cleanly.' . "\n";
}

print 'Email Sent via GMail using an OAuth2 Service Account Key.' . "\n";

?>