Configurable dynamic destination login/logout menu links

These two links allow placing links within Drupal core menus that point to SSO login/logout destinations.
They also include a ?goto= query string in the URL allowing your auth provider to redirect back to where the user was when they clicked the link.

Example values would be: https://auth.mydomain.com/login and https://auth.mydomain.com/logout

title change.

It came to my attention that all new links may not be necessary and just cruft in my system.
The saml_login URL is fine. What I really need is a way to go somewhere besides /user upon login and logout.
Also because we have multiple systems running on the same SSO, I do need an external logout link.

Re-architected so that this feature can be used completely "internally" (default) OR externally and made the query param configurable (I need it for my external logout).

Since I haven't been using the saml_login URL for my login previously (crafted an auto-login feature with an external SSO login form) I'm not 100% this is how you'd like this to work.

This approach is cumbersome and flawed. Fixing now.

Yeah, that's the desire.
I have it working like this...

function simplesamlphp_auth_menu() {
  // MORE ABOVE
  $items['sso-login'] = array(
    'title' => t('Login'),
    'description' => t('Provides dynamic goto login link'),
    'page callback' => 'simplesamlphp_auth_links',
    'page arguments' => array(TRUE),
    'access callback' => TRUE,
    'type' => MENU_NORMAL_ITEM,
  );
  $items['sso-logout'] = array(
    'title' => t('Logout'),
    'description' => t('Provides dynamic goto logout link'),
    'page callback' => 'simplesamlphp_auth_links',
    'page arguments' => array(FALSE),
    'access callback' => TRUE,
    'type' => MENU_NORMAL_ITEM,
  );
  return $items;
}

/**
 * Dynamic referrer login/logout links.
 */
function simplesamlphp_auth_links($login = TRUE) {
  if ($login) {
    $path_array = parse_url($_SERVER['HTTP_REFERER']);
    drupal_goto('saml_login', array('query' => array('destination' => ltrim($path_array['path'], '/'))));
  }
  else {
    // HAVEN'T SOLVED THIS YET.
  }
}

Also, was going to create an admin setting for an "external logout link" that the sso-logout would goto.
I for one had trouble with the single logout service.
In fact mine still returns to /?msg=no_slo even though it actually does bubble up.

Great.
Just realized today we have a problem with logout return heading to HTTPS rather than HTTP.
This is the fix for sure #1446776: Hardcoded URL in logout redirects to wrong URL when logging out

Here's the end of my login page function. Also includes a fix similar to the logout hard-code in #1446776: Hardcoded URL in logout redirects to wrong URL when logging out

  ...

  // Allow dynamic goto after saml_login if that link is used.
  $params = array();
  $query_array = parse_str(htmlspecialchars($_SERVER['QUERY_STRING']));
  if (isset($query_array['destination'])) {
    $params['ReturnTo'] = $query_array['destination'];
  } else {
    // Force returning to intended domain protocol.
    global $base_url;
    $params['ReturnTo'] = $base_url;
  }

  if ($user->uid == 0) {
    // Require the user to be authenticated.
    $_simplesamlphp_auth_as->requireAuth($params);
  }
  else {
    if (isset($params['ReturnTo'])) {
      drupal_goto($params['ReturnTo']);
    }
    else {
      drupal_goto('user/' . $user->uid);
    }
  }
  return $output;
}