Proper Accept Header Validation

ActivityPubPlugin.php

@@ -35,6 +35,7 @@ date_default_timezone_set('UTC');
 // Import required files by the plugin
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'autoload.php';
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'utils' .  DIRECTORY_SEPARATOR . 'discoveryhints.php';
+require_once __DIR__ . DIRECTORY_SEPARATOR . 'utils' .  DIRECTORY_SEPARATOR . 'AcceptHeader.php';
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'utils' .  DIRECTORY_SEPARATOR . 'explorer.php';
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'utils' .  DIRECTORY_SEPARATOR . 'postman.php';
 
@@ -163,6 +164,7 @@ class ActivityPubPlugin extends Plugin
      */
     public function onRouterInitialized(URLMapper $m)
     {
+        if (ActivityPubURLMapperOverwrite::should()) {
             ActivityPubURLMapperOverwrite::variable(
                 $m,
                 'user/:id',
@@ -184,6 +186,7 @@ class ActivityPubPlugin extends Plugin
                 ['id'     => '[0-9]+'],
                 'apNotice'
             );
+        }
 
         $m->connect(
             'user/:id/liked.json',
@@ -944,59 +947,6 @@ class ActivityPubReturn
         echo json_encode($res, JSON_UNESCAPED_SLASHES);
         exit;
     }
-
-    /**
-     * Select content type from HTTP Accept header
-     *
-     * @author Maciej Łebkowski <m.lebkowski@gmail.com>
-     * @param array $mimeTypes Supported Types
-     * @return array|null of supported mime types sorted | null if none valid
-     */
-    public static function getBestSupportedMimeType($mimeTypes)
-    {
-        // XXX: This function needs improvement!
-        if (!isset($_SERVER['HTTP_ACCEPT'])) {
-            return null;
-        }
-
-        // This mime type was messing everything, thus the special case
-        if ($_SERVER['HTTP_ACCEPT'] == 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"') {
-            return true;
-        }
-
-        // Values will be stored in this array
-        $AcceptTypes = [];
-
-        // Accept header is case insensitive, and whitespace isn’t important
-        $accept = strtolower(str_replace(' ', '', $_SERVER['HTTP_ACCEPT']));
-        // divide it into parts in the place of a ","
-        $accept = explode(',', $accept);
-        foreach ($accept as $a) {
-            // the default quality is 1.
-            $q = 1;
-            // check if there is a different quality
-            if (strpos($a, ';q=')) {
-                // divide "mime/type;q=X" into two parts: "mime/type" and "X"
-                list($a, $q) = explode(';q=', $a);
-            }
-            // mime-type $a is accepted with the quality $q
-            // WARNING: $q == 0 means, that mime-type isn’t supported!
-            $AcceptTypes[$a] = $q;
-        }
-        arsort($AcceptTypes);
-
-        $mimeTypes = array_map('strtolower', $mimeTypes);
-
-        // let’s check our supported types:
-        foreach ($AcceptTypes as $mime => $q) {
-            if ($q && in_array($mime, $mimeTypes)) {
-                return $mime;
-            }
-        }
-
-        // no mime-type found
-        return null;
-    }
 }
 
 /**
@@ -1004,19 +954,18 @@ class ActivityPubReturn
  */
 class ActivityPubURLMapperOverwrite extends URLMapper
 {
+    /**
+     * Overwrites a route.
+     *
+     * @author Hannes Mannerheim <h@nnesmannerhe.im>
+     * @param URLMapper $m
+     * @param string $path
+     * @param string $paramPatterns
+     * @param string $newaction
+     * @return void
+     */
     public static function variable($m, $path, $paramPatterns, $newaction)
     {
-        $mimes = [
-            'application/json',
-            'application/activity+json',
-            'application/ld+json',
-            'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'
-        ];
-
-        if (is_null(ActivityPubReturn::getBestSupportedMimeType($mimes))) {
-            return true;
-        }
-
         $m->connect($path, array('action' => $newaction), $paramPatterns);
         $regex = self::makeRegex($path, $paramPatterns);
         foreach ($m->variables as $n => $v) {
@@ -1025,4 +974,35 @@ class ActivityPubURLMapperOverwrite extends URLMapper
             }
         }
     }
+
+    /**
+     * Determines whether the route should or not be overwrited.
+     * If ACCEPT header isn't set false will be returned.
+     *
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     * @return boolean true if it should, false otherwise
+     */
+    public static function should()
+    {
+        // Do not operate without Accept Header
+        if (!isset($_SERVER['HTTP_ACCEPT'])) {
+            return false;
+        }
+
+        $mimes = [
+            'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' => 0,
+            'application/activity+json' => 1,
+            'application/json' => 2,
+            'application/ld+json' => 3
+        ];
+
+        $acceptheader = new AcceptHeader($_SERVER['HTTP_ACCEPT']);
+        foreach ($acceptheader as $ah) {
+            if (isset($mimes[$ah['raw']])) {
+                return true;
+            }
+        }
+
+        return false;
+    }
 }

actions/inbox/Create.php

@@ -65,7 +65,7 @@ try {
 } catch (AlreadyFulfilledException $e) {
     // Notice URI already exists
     common_debug('ActivityPub Inbox Create Note: Note already exists: '.$e->getMessage());
-    ActivityPubReturn::error('Note already exists.',202);
+    ActivityPubReturn::error('Note already exists.', 202);
 } catch (Exception $e) {
     common_debug('ActivityPub Inbox Create Note: Failed Create Note: '.$e->getMessage());
     ActivityPubReturn::error($e->getMessage());

tests/Unit/AcceptHeaderTest.php

@@ -0,0 +1,43 @@
+<?php
+
+require 'AcceptHeader.php';
+
+class ContainerTest extends \PHPUnit_Framework_TestCase
+{
+    public function testHeader1()
+    {
+        $acceptHeader = new AcceptHeader('audio/*; q=0.2, audio/basic');
+        $this->assertEquals('audio/basic', $this->_getMedia($acceptHeader[0]));
+        $this->assertEquals('audio/*; q=0.2', $this->_getMedia($acceptHeader[1]));
+    }
+
+    public function testHeader2()
+    {
+        $acceptHeader = new AcceptHeader('text/*;q=0.3, text/html;q=0.7, text/html;level=1, text/html;level=2;q=0.4, */*;q=0.5');
+        $this->assertEquals('text/html; level=1', $this->_getMedia($acceptHeader[0]));
+        $this->assertEquals('text/html; q=0.7', $this->_getMedia($acceptHeader[1]));
+        $this->assertEquals('*/*; q=0.5', $this->_getMedia($acceptHeader[2]));
+        $this->assertEquals('text/html; level=2; q=0.4', $this->_getMedia($acceptHeader[3]));
+        $this->assertEquals('text/*; q=0.3', $this->_getMedia($acceptHeader[4]));
+    }
+
+    public function testHeader3()
+    {
+        $acceptHeader = new AcceptHeader('text/*, text/html, text/html;level=1, */*');
+        $this->assertEquals('text/html; level=1', $this->_getMedia($acceptHeader[0]));
+        $this->assertEquals('text/html', $this->_getMedia($acceptHeader[1]));
+        $this->assertEquals('text/*', $this->_getMedia($acceptHeader[2]));
+        $this->assertEquals('*/*', $this->_getMedia($acceptHeader[3]));
+    }
+
+    private function _getMedia(array $mediaType)
+    {
+        $str = $mediaType['type'] . '/' . $mediaType['subtype'];
+        if (!empty($mediaType['params'])) {
+            foreach ($mediaType['params'] as $k => $v) {
+                $str .= '; ' . $k . '=' . $v;
+            }
+        }
+        return $str;
+    }
+}

utils/AcceptHeader.php

@@ -0,0 +1,116 @@
+<?php
+/**
+ * Note : Code is released under the GNU LGPL
+ *
+ * Please do not change the header of this file
+ *
+ * This library is free software; you can redistribute it and/or modify it under the terms of the GNU
+ * Lesser General Public License as published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * See the GNU Lesser General Public License for more details.
+ */
+
+/**
+ * The AcceptHeader page will parse and sort the different
+ * allowed types for the content negociations
+ *
+ * @author Pierrick Charron <pierrick@webstart.fr>
+ */
+class AcceptHeader extends \ArrayObject
+{
+    /**
+     * Constructor
+     *
+     * @param string $header Value of the Accept header
+     * @return void
+     */
+    public function __construct($header)
+    {
+        $acceptedTypes = $this->_parse($header);
+        usort($acceptedTypes, [$this, '_compare']);
+        parent::__construct($acceptedTypes);
+    }
+
+    /**
+     * Parse the accept header and return an array containing
+     * all the informations about the Accepted types
+     *
+     * @param string $header Value of the Accept header
+     * @return array
+     */
+    private function _parse($data)
+    {
+        $array = [];
+        $items = explode(',', $data);
+        foreach ($items as $item) {
+            $elems = explode(';', $item);
+
+            $acceptElement = [];
+            $mime = current($elems);
+            list($type, $subtype) = explode('/', $mime);
+            $acceptElement['type'] = trim($type);
+            $acceptElement['subtype'] = trim($subtype);
+            $acceptElement['raw'] = $mime;
+
+            $acceptElement['params'] = [];
+            while (next($elems)) {
+                list($name, $value) = explode('=', current($elems));
+                $acceptElement['params'][trim($name)] = trim($value);
+            }
+
+            $array[] = $acceptElement;
+        }
+        return $array;
+    }
+
+    /**
+     * Compare two Accepted types with their parameters to know
+     * if one media type should be used instead of an other
+     *
+     * @param array $a The first media type and its parameters
+     * @param array $b The second media type and its parameters
+     * @return int
+     */
+    private function _compare($a, $b)
+    {
+        $a_q = isset($a['params']['q']) ? floatval($a['params']['q']) : 1.0;
+        $b_q = isset($b['params']['q']) ? floatval($b['params']['q']) : 1.0;
+        if ($a_q === $b_q) {
+            $a_count = count($a['params']);
+            $b_count = count($b['params']);
+            if ($a_count === $b_count) {
+                if ($r = $this->_compareSubType($a['subtype'], $b['subtype'])) {
+                    return $r;
+                } else {
+                    return $this->_compareSubType($a['type'], $b['type']);
+                }
+            } else {
+                return $a_count < $b_count;
+            }
+        } else {
+            return $a_q < $b_q;
+        }
+    }
+
+    /**
+     * Compare two subtypes
+     *
+     * @param string $a First subtype to compare
+     * @param string $b Second subtype to compare
+     * @return int
+     */
+    private function _compareSubType($a, $b)
+    {
+        if ($a === '*' && $b !== '*') {
+            return 1;
+        } elseif ($b === '*' && $a !== '*') {
+            return -1;
+        } else {
+            return 0;
+        }
+    }
+}