PublicShareController.php

<?php

declare(strict_types=1);
/**
 * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */
namespace OCP\AppFramework;

use OCP\IRequest;
use OCP\ISession;

/**
 * Base controller for public shares
 *
 * It will verify if the user is properly authenticated to the share. If not a 404
 * is thrown by the PublicShareMiddleware.
 *
 * Use this for example for a controller that is not to be called via a webbrowser
 * directly. For example a PublicPreviewController. As this is not meant to be
 * called by a user directly.
 *
 * To show an auth page extend the AuthPublicShareController
 *
 * @since 14.0.0
 */
abstract class PublicShareController extends Controller {

	/**
	 * @since 33.0.0
	 */
	public const DAV_AUTHENTICATED_FRONTEND = 'public_link_authenticated_frontend';

	/** @var string */
	private $token;

	/**
	 * @since 14.0.0
	 */
	public function __construct(
		string $appName,
		IRequest $request,
		protected ISession $session,
	) {
		parent::__construct($appName, $request);
	}

	/**
	 * Middleware set the token for the request
	 *
	 * @since 14.0.0
	 */
	final public function setToken(string $token) {
		$this->token = $token;
	}

	/**
	 * Get the token for this request
	 *
	 * @since 14.0.0
	 */
	final public function getToken(): string {
		return $this->token;
	}

	/**
	 * Get a hash of the password for this share
	 *
	 * To ensure access is blocked when the password to a share is changed we store
	 * a hash of the password for this token.
	 *
	 * @since 14.0.0
	 */
	abstract protected function getPasswordHash(): ?string;

	/**
	 * Is the provided token a valid token
	 *
	 * This function is already called from the middleware directly after setting the token.
	 *
	 * @since 14.0.0
	 */
	abstract public function isValidToken(): bool;

	/**
	 * Is a share with this token password protected
	 *
	 * @since 14.0.0
	 */
	abstract protected function isPasswordProtected(): bool;

	/**
	 * Check if a share is authenticated or not
	 *
	 * @since 14.0.0
	 */
	public function isAuthenticated(): bool {
		// Always authenticated against non password protected shares
		if (!$this->isPasswordProtected()) {
			return true;
		}

		// If we are authenticated properly
		if ($this->validateTokenSession($this->getToken(), $this->getPasswordHash())) {
			return true;
		}

		// Fail by default if nothing matches
		return false;
	}

	/**
	 * Function called if the share is not found.
	 *
	 * You can use this to do some logging for example
	 *
	 * @since 14.0.0
	 */
	public function shareNotFound() {
	}

	/**
	 * Validate the token and password hash stored in session
	 *
	 * @since 33.0.0
	 */
	protected function validateTokenSession(string $token, string $passwordHash): bool {
		$allowedTokensJSON = $this->session->get(self::DAV_AUTHENTICATED_FRONTEND) ?? '[]';
		$allowedTokens = json_decode($allowedTokensJSON, true);
		if (!is_array($allowedTokens)) {
			$allowedTokens = [];
		}

		return ($allowedTokens[$token] ?? '') === $passwordHash;
	}

	/**
	 * Store the token and password hash in session
	 *
	 * @since 33.0.0
	 */
	protected function storeTokenSession(string $token, string $passwordHash = ''): void {
		$allowedTokensJSON = $this->session->get(self::DAV_AUTHENTICATED_FRONTEND) ?? '[]';
		$allowedTokens = json_decode($allowedTokensJSON, true);
		if (!is_array($allowedTokens)) {
			$allowedTokens = [];
		}

		$allowedTokens[$token] = $passwordHash;
		$this->session->set(self::DAV_AUTHENTICATED_FRONTEND, json_encode($allowedTokens));
	}
}