You'll need to send a _POST request via your app with the username and an md5 hash of the user's password. The username field name should be "vb_login_username" and the password field name should be "vb_login_md5password". Once you figure that out, you can create your own custom login page that your app talks to. Here's something similar to what I use. It returns the user's information in JSON format on a successful login.
require_once('./global.php');
require_once(DIR . '/includes/functions_login.php');
define("BADLOGIN" , "You have entered an invalid username or password.");
define("BADLOGIN_STRIKES" , "You have entered an invalid username or password. You have %s login attempts left, after which you will be unable to login for 15 minutes.");
define("BADLOGIN_STRIKES_ZERO" , "You have entered an invalid username or password and used up your failed login quota. Please wait 15 minutes before trying to login again.");
// ################################ start login #################################
if ($_POST['do'] == 'login') {
$vbulletin->input->clean_array_gpc('p', array(
'vb_login_username' => TYPE_STR,
'vb_login_password' => TYPE_STR,
'vb_login_md5password' => TYPE_STR,
'vb_login_md5password_utf' => TYPE_STR,
'cookieuser' => TYPE_BOOL,
));
// can the user login?
$strikes = verify_strike_status($vbulletin->GPC['vb_login_username']);
// make sure our user info stays as whoever we were (for example, we might be logged in via cookies already)
$original_userinfo = $vbulletin->userinfo;
if (!verify_authentication(
$vbulletin->GPC['vb_login_username'], $vbulletin->GPC['vb_login_password'],
$vbulletin->GPC['vb_login_md5password'], $vbulletin->GPC['vb_login_md5password_utf'],
$vbulletin->GPC['cookieuser'], true))
{
exec_strike_user($vbulletin->userinfo['username']);
// load original user
$vbulletin->userinfo = $original_userinfo;
if ($vbulletin->options['usestrikesystem'])
{
if ((5 - $strikes) == 0)
{
die(json_encode(array(
'hasErrors' => (int) 1,
'errorMsg' => BADLOGIN_STRIKES_ZERO
)));
}
else
{
die(json_encode(array(
'hasErrors' => (int) 1,
'errorMsg' => sprintf(BADLOGIN_STRIKES, 5 - $strikes)
)));
}
}
else
{
die(json_encode(array(
'hasErrors' => (int) 1,
'errorMsg' => BADLOGIN
)));
}
}
exec_unstrike_user($vbulletin->GPC['vb_login_username']);
// create new session
process_new_login($vbulletin->GPC['logintype'], $vbulletin->GPC['cookieuser'], $vbulletin->GPC['cssprefs']);
$userinfo = fetch_user($vbulletin->userinfo['userid']);
// is banned user?
if ($userinfo['usergroupid'] == 8) {
process_logout();
}
// return userinfo
die(json_encode(array(
'success' => (int) 1,
'user' => $userinfo
)));
}
Hopefully this helps get you started. By the way, set the field name "cookieuser" to true and the user will be remembered the next time a request is made.