(PHP Extension) Auto-Refresh O365 Access Token when Sending Email

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Demonstrates how to automatically recover from an expired access token when OAuth2 authentication fails in the POP3 protocol. If the server responds with "-ERR Authentication failure: unknown user name or bad password.", then we refresh the access token and retry.

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<?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.

$mailman = new CkMailMan();

$mailman->put_MailHost('outlook.office365.com');
$mailman->put_MailPort(995);
$mailman->put_PopSsl(true);

// Use your O365 email address here.
$mailman->put_PopUsername('OFFICE365_EMAIL_ADDRESS');

// When using OAuth2 authentication, leave the password empty.
$mailman->put_PopPassword('');

// Load our previously obtained OAuth2 access token.
$jsonToken = new CkJsonObject();
$success = $jsonToken->LoadFile('qa_data/tokens/office365.json');
if ($success == false) {
    print $jsonToken->lastErrorText() . "\n";
    exit;
}

$mailman->put_OAuth2AccessToken($jsonToken->stringOf('access_token'));

// Make the TLS connection to the outlook.office365.com POP3 server.
$success = $mailman->Pop3Connect();
if ($success != true) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

// Authenticate using XOAUTH2
$success = $mailman->Pop3Authenticate();
if ($success != true) {
    // If we're still connected to the mail server, then it means the server sent a non-success response,
    // Such as:  -ERR Authentication failure: unknown user name or bad password.
    if ($mailman->get_IsPop3Connected() == true) {

        // Refresh the OAuth2 access token, and if successful, save the new (refreshed) access token and try authenticating again.
        $oauth2 = new CkOAuth2();

        // Use your actual Directory (tenant) ID instead of "112d7ed6-71bf-4eba-a866-738364321bfc"
        $oauth2->put_TokenEndpoint('https://login.microsoftonline.com/112d7ed6-71bf-4eba-a866-738364321bfc/oauth2/v2.0/token');

        // Replace these with your Azure App Registration's actual values.
        $oauth2->put_ClientId('CLIENT_ID');
        $oauth2->put_ClientSecret('CLIENT_SECRET');

        // Get the "refresh_token"
        $oauth2->put_RefreshToken($jsonToken->stringOf('refresh_token'));

        // Send the HTTP POST to refresh the access token..
        $success = $oauth2->RefreshAccessToken();
        if ($success != true) {
            print $oauth2->lastErrorText() . "\n";
            exit;
        }

        print 'New access token: ' . $oauth2->accessToken() . "\n";
        print 'New refresh token: ' . $oauth2->refreshToken() . "\n";

        // Update the JSON with the new tokens.
        $jsonToken->UpdateString('access_token',$oauth2->accessToken());
        $jsonToken->UpdateString('refresh_token',$oauth2->refreshToken());

        // Save the new JSON access token response to a file.
        $sbJson = new CkStringBuilder();
        $jsonToken->put_EmitCompact(false);
        $jsonToken->EmitSb($sbJson);
        $sbJson->WriteFile('qa_data/tokens/office365.json','utf-8',false);

        print 'New Access Token = ' . $oauth2->accessToken() . "\n";

        // Update the mailman with the new access token.
        $mailman->put_OAuth2AccessToken($oauth2->accessToken());

        // Retry the authentication.
        $success = $mailman->Pop3Authenticate();
        if ($success == false) {
            print $mailman->lastErrorText() . "\n";
            exit;
        }

    }
    else {
        print $mailman->lastErrorText() . "\n";
        exit;
    }

}

// Find out how many emails are on the server..
$numEmails = $mailman->CheckMail();
if ($numEmails < 0) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

// Examine the POP3 session log:
print $mailman->pop3SessionLog() . "\n";

// The POP3 session log will look something like this:

// **** Connected to outlook.office365.com:995
// < +OK The Microsoft Exchange POP3 service is ready. [QwBIADIAUABSADEANgBDAEEAMAAwADEAMgAuAG4AYQBtAHAAcgBkADEANgAuAHAAcgBvAGQALgBvAHUAdABsAG8AbwBrAC4AYwBvAG0A]
// > AUTH XOAUTH2
// < + 
// > <base64 string in XOAUTH2 format>
// < -ERR Authentication failure: unknown user name or bad password.
// > AUTH XOAUTH2
// < + 
// > <base64 string in XOAUTH2 format>
// < +OK User successfully authenticated.
// > STAT
// < +OK 248 46637086

// End the POP3 session and close the connection to the GMail server.
$success = $mailman->Pop3EndSession();
if ($success != true) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

print 'Finished.' . "\n";

?>