Token authentication.

includes/islandora_authtokens.inc

@@ -0,0 +1,107 @@
+<?php
+/**
+ * @file
+ *   Library functions for handling authentication tokens.
+ *   These are to be used when dealing with applications
+ *   such as Djatoka that do not pass through credentials.
+ */
+
+// Token lifespan: after this duration the token expires.
+define('TOKEN_TIMEOUT', 30000);
+
+/**
+ * Request Islandora to construct an object/datastream authentication token.
+ * This token can later be turned in for access to the requested object or
+ * datastream.
+ *
+ * @param string $pid
+ *   The Fedora PID to generate the token for.
+ * @param string $dsid
+ *   The Fedora datastream ID to generate the token for.
+ * @param integer $uses
+ *   Defaults to 1.
+ *   The number of uses the token should be used for.  There are
+ *   times when this should be greater than 1: ie. Djatoka needs
+ *   to make two calls.
+ *
+ * @return string
+ *   The generated authentication token.
+ */
+function islandora_get_object_token($pid, $dsid, $uses = 1) {
+  global $user;
+  $time = time();
+  $token = hash("sha256", mt_rand());
+
+  $id = db_insert("islandora_authtokens")->fields(
+    array(
+      'token' => $token,
+      'uid' => $user->uid,
+      'pid' => $pid,
+      'dsid' => $dsid,
+      'time' => $time,
+      'remaining_uses' => $uses,
+    ))->execute();
+
+  return $token;
+}
+
+/**
+ * Submit a token to islandora for authentication. Supply islandora with the
+ * token and the object/datastream it is for and you will receive access if
+ * authentication passes. Tokens can only be redeemed in a short window after
+ * their creation.
+ *
+ * @param string $pid
+ *   The PID of the object to retrieve.
+ * @param string $dsid
+ *   The datastream id to retrieve.
+ * @param string $token
+ *   The registered token that allows access to this object.
+ *
+ * @return mixed
+ *   The user credentials for access if the token validation passes,
+ *   FALSE otherwise
+ */
+function islandora_validate_object_token($pid, $dsid, $token) {
+  // Check for database token.
+  $time = time();
+  $query = db_select('islandora_authtokens', 'tokens');
+  $query->join('users', 'u', 'tokens.uid = u.uid');
+  // The results will look like user objects.
+  $result = $query
+    ->fields('u', array('uid', 'name', 'pass'))
+    ->fields('tokens', array('remaining_uses'))
+    ->condition('token', $token, '=')
+    ->condition('pid', $pid, '=')
+    ->condition('dsid', $dsid, '=')
+    ->condition('time', $time, '<=')
+    ->condition('time', $time - TOKEN_TIMEOUT, '>')
+    ->execute()
+    ->fetchAll();
+  if ($result) {
+    $remaining_uses = $result[0]->remaining_uses;
+    $remaining_uses--;
+    // Remove the authentication token so it can't be used again.
+    if ($remaining_uses == 0) {
+      db_delete("islandora_authtokens")
+        ->condition('token', $token, '=')
+        ->condition('pid', $pid, '=')
+        ->condition('dsid', $dsid, '=')
+        ->execute();
+    }
+    // Decrement authentication token uses.
+    else {
+      db_update("islandora_authtokens")
+      ->fields(array('remaining_uses' => $remaining_uses))
+      ->condition('token', $token, '=')
+      ->condition('pid', $pid, '=')
+      ->condition('dsid', $dsid, '=')
+      ->execute();
+    }
+    unset($result[0]->remaining_uses);
+    return $result[0];
+  }
+  else {
+    return FALSE;
+  }
+}

islandora.install

@@ -1,15 +1,13 @@
 <?php
-
 /**
  * @file
- *
- * This file contains all install related hooks.
+ *   This file contains all install related hooks.
  */
 
 /**
  * Implements hook_install().
  *
- * @see islandora_islandora_required_objects().
+ * @see islandora_islandora_required_objects()
  */
 function islandora_install() {
   module_load_include('inc', 'islandora', 'includes/solution_packs');
@@ -19,9 +17,81 @@ function islandora_install() {
 /**
  * Implements hook_uninstall().
  *
- * @see islandora_islandora_required_objects().
+ * @see islandora_islandora_required_objects()
  */
 function islandora_uninstall() {
   module_load_include('inc', 'islandora', 'includes/solution_packs');
   islandora_install_solution_pack('islandora', 'uninstall');
 }
+
+/**
+ * Implements hook_schema().
+ *
+ * @return array
+ *   The database schema for the module.
+ */
+function islandora_schema() {
+  $schema['islandora_authtokens'] = array(
+    'description' => 'The hub for all islandora authentication tokens',
+    'fields' => array(
+      'id' => array(
+        'description' => 'key',
+        'type' => 'serial',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+      ),
+      'token' => array(
+        'description' => 'a unique identifier for this token',
+        'type' => 'varchar',
+        'length' => 64,
+      ),
+      'remaining_uses' => array(
+        'description' => 'How many uses until this should be removed',
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+      ),
+      'uid' => array(
+        'description' => 'the user id that requested this token',
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+      ),
+      'time' => array(
+        'description' => 'when this token was created',
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+      ),
+      'pid' => array(
+        'description' => 'the pid of the object this token unlocks',
+        'type' => 'varchar',
+        'length' => 128,
+        'not null' => TRUE,
+      ),
+      'dsid' => array(
+        'description' => 'the datasteram id of the object this token unlocks',
+        'type' => 'varchar',
+        'length' => 32,
+        'not null' => TRUE,
+      ),
+    ),
+    'unique keys' => array(
+      'id' => array('id'),
+    ),
+    'primary key' => array('id'),
+  );
+  return $schema;
+}
+
+/**
+ * Implements hook_update_N().
+ *
+ * Add the required table for handling authentication tokens.
+ * This is the first instance that has this table.
+ */
+function islandora_update_7001(&$sandbox) {
+  drupal_install_schema('islandora');
+  $t = get_t();
+  return $t("Islandora database updates complete");
+}

islandora.module

@@ -161,10 +161,13 @@ function islandora_menu() {
     'access arguments' => array(FEDORA_VIEW, 2, 4),
     'load arguments' => array(2),
   );
-  $items['islandora/object/%islandora_object/datastream/%islandora_datastream/view'] = array(
+  // This menu item uses token authentication in islandora_tokened_object.
+  $items['islandora/object/%islandora_tokened_object/datastream/%islandora_tokened_datastream/view'] = array(
     'title' => 'View datastream',
+    'load arguments' => array('%map'),
     'type' => MENU_DEFAULT_LOCAL_TASK,
   );
+   
   $items['islandora/object/%islandora_object/datastream/%islandora_datastream/download'] = array(
     'title' => 'Download datastream',
     'page callback' => 'islandora_download_datastream',
@@ -518,6 +521,50 @@ function islandora_object_load($object_id) {
   return NULL;
 }
 
+/**
+ * A helper function to get a connection and return an object using a token
+ * for authentication.
+ *
+ * @param string $object_id
+ *   The PID of an object in the menu path identified by
+ *   '%islandora_tokened_object'.
+ * @param array $map
+ *   Used to extract the Fedora object's DSID at $map[4].
+ * 
+ * @return FedoraObject
+ *   A token authenticated object. @see islandora_object_load
+ */
+function islandora_tokened_object_load($object_id, $map) {
+  if (array_key_exists('token', $_GET)) {
+    $token = $_GET['token'];
+    if ($token) {
+      module_load_include('inc', 'islandora', 'includes/islandora_authtokens');
+      $token_user = islandora_validate_object_token($object_id, $map[4], $token);
+      islandora_get_tuque_connection($user = $token_user);
+    }
+  }
+  return islandora_object_load($object_id);
+}
+
+/**
+ * This datastream load must take in arguments in a different 
+ * order than the usual islandora_datastream_load.  This is because 
+ * the function islandora_tokened_object_load needs DSID. It uses
+ * the path %map to avoid duplicate parameters.
+ * 
+ * @param mixed $datastream_id
+ *   %islandora_tokened_datastream @see islandora_datastream_load
+ * @param array $map
+ *   Used to extract the Fedora object's PID at $map[2].
+ * 
+ * @return FedoraDatastream
+ *   A datastream from Fedora.
+ *   @see islandora_datastream_load
+ */
+function islandora_tokened_datastream_load($datastream_id, $map) {
+  return islandora_datastream_load($datastream_id, $map[2]);
+}
+
 /**
  * A helper function to get an datastream specified as '%islandora_datastream'
  * for the object specified in the menu path as '%islandora_object'.
@@ -526,11 +573,13 @@ function islandora_object_load($object_id) {
  * drupal_access_denied() when appropriate.
  *
  * @param string $datastream_id
- *   The dsid of the datastream specified as '%islandora_datastream' to fetch
+ *   The DSID of the datastream specified as '%islandora_datastream' to fetch
  *   from the given object in the menu path identified by '%islandora_object'.
  *
- * $param string $object_id
- *   The object to load the datastream from.
+ * @param mixed $object_id
+ *   The object to load the datastream from.  This can be a Fedora PID or 
+ *   an instantiated IslandoraFedoraObject as it implements __toString() 
+ *   returning the PID.
  *
  * @return FedoraDatastream
  *   If the given datastream ID exists then this returns a FedoraDatastream