Add PublicPage documentation

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

developer_manual/app/index.rst

@@ -26,6 +26,7 @@ App development
    notifications
    logging
    repair
+   publicpage
    testing
    ../api
 

developer_manual/app/publicpage.rst

@@ -0,0 +1,156 @@
+============
+Public Pages
+============
+
+A lot of apps in Nextcloud want to expose public pages in some form. This can
+be to share files, a calendar or anything else. To ensure all those pages
+benefit fromt he security enhancements we add we created simple controlers
+for app developers to use.
+
+Concept
+-------
+
+A public page is there to display a resource that a user wants to expose via a
+public link in an app.
+
+A public page is identified by some ``token`` and can be protected by a ``password``.
+
+If a public page is password protected by default we will show the normal authentication
+page to enter the password.
+
+A public page can also call other endpoints. These endpoints operate very similarly
+witht he difference that if the user is not properly authenticated it will throw a 404.
+
+It is required that you have a parameter (probaby in your url) with the ``token``. As an example
+your ``routes.php`` could look like:
+
+.. code-block:: php
+
+	<?php
+	return [
+		'routes' => [
+			[ 'name' => 'PublicAPI#get', 'url' => '/api/{token}', 'verb' => 'GET' ],
+			[ 'name' => 'PublicDisplay#get', 'url' => '/display/{token}', 'verb' => 'GET' ],
+		]
+	];
+
+Implementing an API called from a public share page
+---------------------------------------------------
+
+As said the PublicShareController is a very basic controller. You need to implement 3 functions.
+``isPasswordProtected``, ``isValidToken`` and ``getPasswordHash``.
+
+.. code-block:: php
+
+	<?php
+
+	namespace OCA\Share_Test\Controller;
+
+	use OCP\AppFramework\PublicShareController;
+
+	class PublicAPIController extends PublicShareController {
+		/**
+		 * Return the hash of the password for this share.
+		 * This function is of course only called when isPasswordProtected is true
+		 */
+		protected function getPasswordHash(): string {
+			return md5('secretpassword');
+		}
+
+		/**
+		* Validate the token of this share. If the token is invalid this controller
+		* will return a 404.
+		*/
+		public function isValidToken(): bool {
+			return $this->getToken() === 'secretToken';
+		}
+
+		/**
+		 * Allows you to specify if this share is password protected
+		 */
+		protected function isPasswordProtected(): bool {
+			return true;
+		}
+
+		/**
+		 * Your normal controller function
+		 */
+		public function get() {
+			// Work your magic
+		}
+	}
+
+
+You can also chose to overwrite the ``shareNotFound`` function. That is called when the
+token is not valid. You can do additional logging here for example.
+
+
+Implementing an authenticated public page
+-----------------------------------------
+
+On some pages password authentication might be required (just like the when you
+share a file via public link with a password). In this case you need
+to extend a different provider.
+
+The AuthPublicShareController requiers in addition to the PublicShareController that
+you also implement the ``verifyPassword`` and ``showShare`` functions.
+
+.. code-block: php
+
+	<?php
+
+	namespace OCA\Share_Test\Controller;
+
+	use OCP\AppFramework\AuthPublicShareController;
+
+	class PublicDisplayController extends AuthPublicShareController {
+		/**
+		 * Return the hash of the password for this share.
+		 * This function is of course only called when isPasswordProtected is true
+		 */
+		protected function getPasswordHash(): string {
+			return md5('secretpassword');
+		}
+
+		/**
+		* Validate the token of this share. If the token is invalid this controller
+		* will return a 404.
+		*/
+		public function isValidToken(): bool {
+			return $this->getToken() === 'secretToken';
+		}
+
+		/**
+		 * Allows you to specify if this share is password protected
+		 */
+		protected function isPasswordProtected(): bool {
+			return true;
+		}
+
+		/**
+		 * Verify the entered password by the user
+		 */
+		protected function verifyPassword(string $password): bool {
+			return $password === 'secretpassword';
+		}
+
+		public function showShare(): TemplateResponse {
+			return new TemplateResponse('yourapp', 'yourtemplate');
+		}
+
+		/**
+		 * Your normal controller function
+		 */
+		public function get() {
+			// Work your magic
+		}
+	}
+
+
+Additionally you can overwrite the ``showAuthenticate`` and ``showAuthFailed`` functions
+if you do now want to use the default authentication pages.
+
+The ``authFailed`` and ``authSucceeded`` functions can be overwritten as well and are
+called depending on the if authentication passed or not. You can handle additional logging
+there for example.
+