nextcloud/lib/private/connector/sabre/auth.php

<?php
namespace OC\Connector\Sabre;

class Auth extends \Sabre\DAV\Auth\Backend\AbstractBasic {
	const DAV_AUTHENTICATED = 'AUTHENTICATED_TO_DAV_BACKEND';

	/**
	 * Whether the user has initially authenticated via DAV
	 *
	 * This is required for WebDAV clients that resent the cookies even when the
	 * account was changed.
	 *
	 * @see https://github.com/owncloud/core/issues/13245
	 *
	 * @param string $username
	 * @return bool
	 */
	protected function isDavAuthenticated($username) {
		return !is_null(\OC::$server->getSession()->get(self::DAV_AUTHENTICATED)) &&
		\OC::$server->getSession()->get(self::DAV_AUTHENTICATED) === $username;
	}

	/**
	 * Validates a username and password
	 *
	 * This method should return true or false depending on if login
	 * succeeded.
	 *
	 * @param string $username
	 * @param string $password
	 * @return bool
	 */
	protected function validateUserPass($username, $password) {
		if (\OC_User::isLoggedIn() &&
			$this->isDavAuthenticated(\OC_User::getUser())
		) {
			\OC_Util::setupFS(\OC_User::getUser());
			\OC::$server->getSession()->close();
			return true;
		} else {
			\OC_Util::setUpFS(); //login hooks may need early access to the filesystem
			if(\OC_User::login($username, $password)) {
			        // make sure we use owncloud's internal username here
			        // and not the HTTP auth supplied one, see issue #14048
			        $ocUser = \OC_User::getUser();
				\OC_Util::setUpFS($ocUser);
				\OC::$server->getSession()->set(self::DAV_AUTHENTICATED, $ocUser);
				\OC::$server->getSession()->close();
				return true;
			} else {
				\OC::$server->getSession()->close();
				return false;
			}
		}
	}

	/**
	 * Returns information about the currently logged in username.
	 *
	 * If nobody is currently logged in, this method should return null.
	 *
	 * @return string|null
	 */
	public function getCurrentUser() {
		$user = \OC_User::getUser();
		if($user && $this->isDavAuthenticated($user)) {
			return $user;
		}
		return null;
	}

	/**
	  * Override function here. We want to cache authentication cookies
	  * in the syncing client to avoid HTTP-401 roundtrips.
	  * If the sync client supplies the cookies, then OC_User::isLoggedIn()
	  * will return true and we can see this WebDAV request as already authenticated,
	  * even if there are no HTTP Basic Auth headers.
	  * In other case, just fallback to the parent implementation.
	  *
	  * @param \Sabre\DAV\Server $server
	  * @param $realm
	  * @return bool
	  */
	public function authenticate(\Sabre\DAV\Server $server, $realm) {

		$result = $this->auth($server, $realm);
		return $result;
    }

	/**
	 * @param \Sabre\DAV\Server $server
	 * @param $realm
	 * @return bool
	 */
	private function auth(\Sabre\DAV\Server $server, $realm) {
		if (\OC_User::handleApacheAuth() ||
			(\OC_User::isLoggedIn() && is_null(\OC::$server->getSession()->get(self::DAV_AUTHENTICATED)))
		) {
			$user = \OC_User::getUser();
			\OC_Util::setupFS($user);
			$this->currentUser = $user;
			\OC::$server->getSession()->close();
			return true;
		}

		return parent::authenticate($server, $realm);
	}
}