Perl

Get GMail IMAP OAuth2 Access Token for Desktop App

See more GMail SMTP/IMAP/POP Examples

Demonstrates how to get a GMail IMAP OAuth2 access token from a desktop application or script, which can be used with the XOAUTH2 authentication method.

This example requires a browser window to be displayed to allow the GMail account owner to authorize the access. The code for displaying the web browser is omitted. Suggestions for a few programming languages are provided in code comments. You'll need to find out how to display a web browser and navigate to the URL returned by the call to oauth2.StartAuth.

Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

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

my $oauth2 = Chilkat2::OAuth2->new;

# For Google OAuth2, set the listen port equal to the port used
# in the Authorized Redirect URL for the Client ID.
# For example, in this case the Authorized Redirect URL would be http://localhost:3017/
# Your app should choose a port not likely not used by any other application.
$oauth2->ListenPort(3017);

$oauth2->AuthorizationEndpoint('https://accounts.google.com/o/oauth2/v2/auth');
$oauth2->TokenEndpoint('https://www.googleapis.com/oauth2/v4/token');

# Replace these with actual values.
$oauth2->ClientId('GOOGLE-CLIENT-ID');
$oauth2->ClientSecret('GOOGLE-CLIENT-SECRET');

$oauth2->CodeChallenge(1);
$oauth2->CodeChallengeMethod('S256');

# This is the full-permissions scope for GMail, which would allow full IMAP read/write access.
$oauth2->Scope('https://mail.google.com/');

# Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
my $url = $oauth2->StartAuth();
if (!$oauth2->LastMethodSuccess) {
    print $oauth2->LastErrorText, "\n";
    exit;
}

# Launch the system's default browser navigated to the URL.
my $success = $oauth2->LaunchBrowser($url);
if (!$success) {
    print $oauth2->LastErrorText, "\n";
    exit;
}

# Now wait for the authorization.
# We'll wait for a max of 30 seconds.
my $numMsWaited = 0;
while (($numMsWaited < 30000) && ($oauth2->AuthFlowState < 3)) {
    $oauth2->SleepMs(100);
    $numMsWaited = $numMsWaited + 100;
}

# If there was no response from the browser within 30 seconds, then
# the AuthFlowState will be equal to 1 or 2.
# 1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
# 2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
# In that case, cancel the background task started in the call to StartAuth.
if ($oauth2->AuthFlowState < 3) {
    $oauth2->Cancel();
    print "No response from the browser!\n";
    exit;
}

# Check the AuthFlowState to see if authorization was granted, denied, or if some error occurred
# The possible AuthFlowState values are:
# 3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
# 4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
# 5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.
if ($oauth2->AuthFlowState == 5) {
    print "OAuth2 failed to complete.\n";
    print $oauth2->FailureInfo, "\n";
    exit;
}

if ($oauth2->AuthFlowState == 4) {
    print "OAuth2 authorization was denied.\n";
    print $oauth2->AccessTokenResponse, "\n";
    exit;
}

if ($oauth2->AuthFlowState != 3) {
    print 'Unexpected AuthFlowState:', $oauth2->AuthFlowState, "\n";
    exit;
}

# Save the full JSON access token response to a file.
my $sbJson = Chilkat2::StringBuilder->new;
$sbJson->Append($oauth2->AccessTokenResponse);
$sbJson->WriteFile('qa_data/tokens/_gmailFullAccess.json', 'utf-8', 0);

# The saved JSON response looks like this:

#     {
#      "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtABCHkZzrwlARkwX6R3O0PCDEzRlfaQ",
#      "token_type": "Bearer",
#      "expires_in": 3600,
#      "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
#     }
#
print "OAuth2 authorization granted!\n";
print 'Access Token: ', $oauth2->AccessToken, "\n";