error_code_451.php

<?php
/*
Plugin Name: Error Code 451
Plugin URI: http://github.com/451hackathon/wpplugin
Description: Wordpress plugin to block pages using Error Code 451.
Version: 0.1
Author: Ulrike, Tara
License: GPL3+
Text Domain: error_451
Domain Path: /languages/
*/

/*
    Copyright 2017 Ulrike <u@451f.org>, Tara <me@tarakyiee.com>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2, as
    published by the Free Software Foundation.

    This program 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

$cfg['json_filename'] = "blocked_content_ids.json";
$cfg['plugin_name'] = "Error Code 451 Plugin";
$cfg['plugin_version'] = "0.1";

/* Plugin l10n */
function error_code_451_init() {
       $plugin_dir = plugins_url('', __FILE__);
    load_plugin_textdomain( 'error_451', false, "$plugin_dir/languages" );
}
add_action('plugins_loaded', 'error_code_451_init');

/* get user IP */
function get_the_user_ip() {
    if ( ! empty( $_SERVER['HTTP_CLIENT_IP'] ) ) {
        // check ip from share internet
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    } elseif ( ! empty( $_SERVER['HTTP_X_FORWARDED_FOR'] ) ) {
        // to check ip is pass from proxy
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    } else {
        $ip = $_SERVER['REMOTE_ADDR'];
    }
    return apply_filters( 'wpb_get_ip', $ip );
}

function get_client_geocode() {
      // Get visitor geo origin
      $json_url = 'http://freegeoip.net/json/' . get_the_user_ip();
      $options = array(
          CURLOPT_RETURNTRANSFER => true,
          CURLOPT_HTTPHEADER => array('Content-type: application/json') ,
      );
      $ch = curl_init( $json_url );
      curl_setopt_array( $ch, $options );
      $ch_result = curl_exec($ch);
      $geo_ip = json_decode($ch_result);
      if($geo_ip->country_code)
          return $geo_ip->country_code;
}

// Sanitize IDs, may contain letters, numbers, dots and commas.
function sanitize_comma_separated($input) {
    $input = preg_replace("/[^a-zA-Z0-9\.\,\:]+/", "", $input);
    $input = str_replace(array('\r', '\n', '%0a', '%0d' ), '', trim($input));
    return $input;
}

/* writes array data to JSON */
function write_json($data, $filename) {
    $plugin_dir = realpath(dirname(__FILE__));
	if (is_writable($plugin_dir/$filename)) {
		$handler = fopen("$plugin_dir/$filename", "w+");
		fwrite($handler, json_encode($data));
		fclose($handler);
		return true;
	} else {
		 return new WP_Error('broke', __('The JSON file containing post ids which are blocked cannot be written. Please make sure that the plugin directory is writable by the webserver.', 'error_451'));
	}
}

/* read arraay from JSON */
function read_json($filename) {
    $plugin_dir = realpath(dirname(__FILE__));
    if(file_exists("$plugin_dir/$filename")) {
        $data = json_decode(file_get_contents("$plugin_dir/$filename"));
        return $data;
    }
}

// this will be useful for having a sitemap of blocked files as well as for the loops and RSS loop.
function find_blocked_content_ids() {
    global $cfg;
    $i = 0;
    // we want to create an array of all blocked content
    $blocked_content_args = array(
        'meta_query' => array(
            array(
                'key' => 'error_451_blocking',
                'value' => 'yes'
            )
        )
    );
    $blocked_content_query = new WP_Query( $blocked_content_args );
    foreach ($blocked_content_query->posts as $post) {
        $blocked_content_ids[$i]['post_id'] = $post->ID;
        $blocked_content_ids[$i]['blocked_countries'] = get_post_meta( $post->ID, 'error_451_blocking_countries', true);
        $i++;
    }
    write_json($blocked_content_ids, $cfg['json_filename']);
}

// save all blocked content to JSON file when updating a post.
add_action( 'save_post', 'find_blocked_content_ids', 10, 2 );


// the function that alters post titles
function alter_censored_title( $title ) {
    global $post;
    if($post AND compare_post_with_location($post->ID)) {
        $title = __("Error 451 - Unavailable For Legal Reasons.", 'error_451') ;
    }
    return $title;
}

// the function that alters post content
function alter_censored_content( $content ) {
    global $post;
    if($post AND compare_post_with_location($post->ID)) {
        $content = user_error_message($post->ID);
    }
    return $content;
}

// hide the blocked post thumbnail.
function alter_censored_thumbnail( $html, $post_id, $post_thumbnail_id, $size, $attr) {
    global $post;
    if($post AND compare_post_with_location($post->ID)) {
		$html = "";
	}
    return $html;
}

function compare_post_with_location($post_id) {
    global $cfg;
    $blocked_content_ids = read_json($cfg['json_filename']);
    foreach($blocked_content_ids as $blocked_content) {
        $post_ids[] = $blocked_content->post_id;
    }
    if(in_array( $post_id, $post_ids, true ) AND error_451_check_client_location_against_block($post_id)) {
        return true;
    }
    return false;
}

// add the filter when main loop starts
add_action( 'loop_start', function( WP_Query $query ) {
    if ($query->is_archive() || $query->is_feed() || $query->is_home() || $query->is_search() || $query->is_tag() && $query->is_main_query()) {
        add_filter( 'the_title', 'alter_censored_title', -10, 1 );
        add_filter( 'the_content', 'alter_censored_content', -10, 1 );
        add_filter( 'post_thumbnail_html', 'alter_censored_thumbnail', -10, 5 );
   }
});

// remove the filter when main loop ends
add_action( 'loop_end', function( WP_Query $query ) {
   if ( has_filter( 'the_title', 'alter_censored_title' ) ) {
       remove_filter( 'the_title', 'alter_censored_title' );
   }
   if ( has_filter( 'the_content', 'alter_censored_content' ) ) {
       remove_filter( 'the_content', 'alter_censored_content' );
   }
   if ( has_filter( 'post_thumbnail_html', 'alter_censored_thumbnail' ) ) {
       remove_filter( 'post_thumbnail_html', 'alter_censored_thumbnail' );
   }
});

/*
// alter the query to not display these posts.
function error_451_check_partial_blocked_content($query) {
    global $cfg;
    $blocked_content_ids = read_json($cfg['json_filename']);
    if ($query->is_archive() || $query->is_feed() || $query->is_home() || $query->is_search() || $query->is_tag() && $query->is_main_query()) {
        foreach($blocked_content_ids as $blocked_content) {
            $post_ids[] = $blocked_content->post_id;
        }
        $query->set('post__not_in', $post_ids);
    }
}

// Check for blocked content on page load
add_action( 'pre_get_posts', 'error_451_check_partial_blocked_content');
*/

function error_451_check_client_location_against_block($post_id) {
    // get client Geolocation
    $client_geo_origin = get_client_geocode();

    // check post
    if(get_post_meta( $post_id, 'error_451_blocking', true) == "yes" AND isset($client_geo_origin) && $_COOKIE["ignore"] != 1) {
        //get blocked countries from post metadata
        $blocked_countries = explode(',', get_post_meta( $post_id, 'error_451_blocking_countries', true));
        if( in_array($client_geo_origin, $blocked_countries) || empty($blocked_countries[0]) ) {
            return true;
        }
    }
    return false;
}

// Serve 451 http_response_code and send additional headers
function error_451_check_blocked() {
    // Get access to the current WordPress object instance
    // Get the base URL & post ID
    global $wp;
    $current_url = home_url(add_query_arg(array(),$wp->request));
    $current_url = $current_url . $_SERVER['REDIRECT_URL'];
    $post_id = url_to_postid($current_url);

    if(error_451_check_client_location_against_block($post_id)) {
        $error_code = 451;
        $site_url = site_url();
        $script_url = plugins_url('', __FILE__).'/js/error_451.js';
        $blocking_authority = get_post_meta($post_id, 'error_451_blocking_authority', true);

        // send additional headers
        header('Link: <'.$site_url.'>; rel="blocked-by"', false, $error_code);
        header('Link: <'.$blocking_authority.'>; rel="blocking-authority"', false, $error_code);

        // redirect to get the correct HTTP status code for this page.
        wp_redirect("/451", 451);
        $user_error_message  = '<html><head><script type="text/javascript" src="'.$script_url.'"></script>
                                </head><body><h1>'.__('451 Unavailable For Legal Reasons', 'error_451').'</h1>';
        $user_error_message .= user_error_message($post_id);
        $user_error_message .= '</body></html>';
        echo $user_error_message;
        exit;
    }
}

function user_error_message($post_id) {
    $options = get_option('error_code_451_option_name');
    $blocking_authority = get_post_meta($post_id, 'error_451_blocking_authority', true);
    $blocking_description = get_post_meta($post_id, 'error_451_blocking_description', true);

    $user_error_message .= '<p>'.__('This status code indicates that the server is denying access to the resource as a consequence of a legal demand.', 'error_451').'</p>';
    if(!empty($blocking_authority)) {
        $user_error_message .= '<p>'.__('The blocking of this content has been requested by', 'error_451').' <a href="'.$blocking_authority.'">'.$blocking_authority.'</a>.';
    }
    if(!empty($blocking_description)) {
        $user_error_message .= '<p>'.$blocking_description.'</p>';
    }
    if($options['CSV']) {
          $user_error_message .= '<p><a href="#" onclick="setError451Ignore()">'.__('If you believe this message is an error and that you are legally entitled to access the content, click here.', 'error_451').'</a> '.__('Note: This will set a cookie on your device that will expire in 1 hour.', 'error_451').'</p>';
    }
    $user_error_message .= '<p><a href="https://gettor.torproject.org/">'.__('On an unrelated note, Get Tor.', 'error_451').'</a></p>';
    return $user_error_message;
}

// call javascript
function error_451_scripts() {
   wp_register_script( 'blocked', plugins_url('', __FILE__).'/js/error_451.js', 0, 0, true );
   wp_enqueue_script( 'blocked' );
}
add_action( 'wp_enqueue_scripts', 'error_451_scripts' );

/* Check for blocked content on page load */
add_action( 'init', 'error_451_check_blocked');

/* Meta box setup function. */
function error_451_post_meta_boxes_setup() {
    /* Add meta boxes on the 'add_meta_boxes' hook. */
    add_action( 'add_meta_boxes', 'error_451_add_post_meta_boxes' );

    /* Save post meta on the 'save_post' hook. */
    add_action( 'save_post', 'error_451_save_blocking_meta', 10, 2 );
}

/* Create meta box to be displayed on the post editor screen. */
function error_451_add_post_meta_boxes() {
    add_meta_box(
        'error-451-blocking', // Unique ID
        esc_html__( 'Configure blocking / Error 451', 'error-451' ), // Title
        'error_451_meta_box',  // Callback function
        'post',         // Admin page (or post type)
        'side',         // Context
        'default'       // Priority
    );

     add_meta_box(
          'error-451-blocking-page', // Unique ID
          esc_html__( 'Configure blocking / Error 451', 'error-451' ), // Title
          'error_451_meta_box',  // Callback function
          'page',         // Admin page (or post type)
          'side',         // Context
          'default'       // Priority
      );
}

/* Display the post meta box. */
function error_451_meta_box( $post ) {
  wp_nonce_field( basename( __FILE__ ), 'error_451_blocking_nonce' ); ?>

  <p>
    <?php $error_451_blocking = get_post_meta($post->ID, 'error_451_blocking', true); ?>
    <label for="error_451_blocking">
    <input class="checkbox" type="checkbox" name="error_451_blocking" id="error_451_blocking" value="yes" <?php if($error_451_blocking == "yes") { echo ' checked="checked"'; } ?> />
    <?php _e( "If you have to enable blocking of this content, please check the box.", 'error_451' ); ?></label>
  </p>

  <p>
    <label for="error_451-blocking_countries"><?php _e( "Add comma-separated list of country codes where this page shall be blocked. When left empty, the content shall be blocked from all locations.", 'error_451' ); ?></label>
    <br />
    <input class="widefat" type="text" name="error_451_blocking_countries" id="error_451_blocking_countries" value="<?php echo esc_attr( get_post_meta( $post->ID, 'error_451_blocking_countries', true ) ); ?>" size="30" />
  </p>

  <p>
    <label for="error_451_blocking_authority"><?php _e( "Please specify the URL of the authority has requested the block.", 'error_451' ); ?></label>
    <br />
    <input class="widefat" type="url" name="error_451_blocking_authority" id="error_451_blocking_authority" value="<?php echo esc_attr( get_post_meta( $post->ID, 'error_451_blocking_authority', true ) ); ?>" size="256" />
  </p>

  <p>
    <label for="error_451_blocking_description"><?php _e( "You may optionally specify a description so that visitors know why the page is blocked.", 'error_451' ); ?></label>
    <br />
    <input class="widefat" type="text" name="error_451_blocking_description" id="error_451_blocking_description" value="<?php echo esc_attr( get_post_meta( $post->ID, 'error_451_blocking_description', true ) ); ?>" size="256" />
  </p>
<?php }

/* Save the meta box's post metadata. */
function error_451_save_blocking_meta( $post_id, $post ) {

    /* Verify the nonce before proceeding. */
    if ( !isset( $_POST['error_451_blocking_nonce'] ) || !wp_verify_nonce( $_POST['error_451_blocking_nonce'], basename( __FILE__ ) ) )
      return $post_id;

    /* Get the post type object. */
    $post_type = get_post_type_object( $post->post_type );

    /* Check if the current user has permission to edit the post. */
    if ( !current_user_can( $post_type->cap->edit_post, $post_id ) )
        return $post_id;

    // which meta keys do we want to update?
    $meta_keys = array('error_451_blocking', 'error_451_blocking_authority', 'error_451_blocking_countries', 'error_451_blocking_description');


    /* Get the posted data and sanitize it. */
    foreach($meta_keys as $meta_key) {
        if($meta_key == 'error_451_blocking_countries') {
            $new_meta_value[$meta_key] = ( isset( $_POST[$meta_key] ) ? sanitize_comma_separated( $_POST[$meta_key] ) : '' );
        } else {
            $new_meta_value[$meta_key] = ( isset( $_POST[$meta_key] ) ? sanitize_text_field( $_POST[$meta_key] ) : '' );
        }

        /* Get the meta value of the custom field key. */
        $meta_value = get_post_meta( $post_id, $meta_key, true );

        /* If a new meta value was added and there was no previous value, add it. */
        if ( $new_meta_value[$meta_key] && '' == $meta_value ) {
            add_post_meta( $post_id, $meta_key, $new_meta_value[$meta_key], true );
        }

        /* If the new meta value does not match the old value, update it. */
        elseif ( $new_meta_value[$meta_key] && $new_meta_value[$meta_key] != $meta_value ) {
            update_post_meta( $post_id, $meta_key, $new_meta_value[$meta_key] );
    }

    /* If there is no new meta value but an old value exists, delete it. */
    elseif ( '' == $new_meta_value[$meta_key] && $meta_value ) {
        delete_post_meta( $post_id, $meta_key, $meta_value );
    }

    }
}

/* Fire meta box setup function on the post editor screen. */
add_action( 'load-post.php', 'error_451_post_meta_boxes_setup' );
add_action( 'load-post-new.php', 'error_451_post_meta_boxes_setup' );

/* Save post meta on the 'save_post' hook. */
add_action( 'save_post', 'error_451_save_blocking_meta', 10, 2 );

// Create configuration page for wp-admin. Each domain shall configure their REPORTING_URL, API_EMAIL, HOST and results page.
class errorCode451SettingsPage {
    /**
     * Holds the values to be used in the fields callbacks
     */
    private $options;
    /**
     * Start up
     */
    public function __construct() {
        add_action( 'admin_menu', array( $this, 'add_plugin_page' ) );
        add_action( 'admin_init', array( $this, 'page_init' ) );
    }
    /**
     * Add options page
     */
    public function add_plugin_page() {
        // This page will be under "Settings"
        add_options_page(
            'Settings Admin',
            'Error Code 451 Settings',
            'manage_options',
            'error-code-451-settings',
            array( $this, 'create_admin_page' )
        );
    }
    /**
     * Options page callback
     */
    public function create_admin_page() {
        // Set class property
        $this->options = get_option( 'error_code_451_option_name' );
        ?>
        <div class="wrap">
            <?php screen_icon(); ?>
            <h2><?php _e('Settings Error Code 451'); ?></h2>
            <form method="post" action="options.php">
            <?php
                // This prints out all hidden setting fields
                settings_fields( 'error_code_451_option_group' );
                do_settings_sections( 'error-code-451-settings' );
                submit_button();
            ?>
            </form>
        </div>
        <?php
    }
    /**
     * Register and add settings
     */
    public function page_init() {
        register_setting(
            'error_code_451_option_group', // Option group
            'error_code_451_option_name', // Option name
            array( $this, 'sanitize' ) // Sanitize
        );
        add_settings_section(
            'error_code_451_section_general', // ID
            'Reporting Settings', // Title
            array( $this, 'print_section_info' ), // Callback
            'error-code-451-settings' // Page
        );
        add_settings_field(
            'REPORTING_URL',
            'Reporting URL',
            array( $this, 'api_key_callback' ),
            'error-code-451-settings',
            'error_code_451_section_general'
        );
        add_settings_field(
            //ClientSideVerification
            'CSV',
            'Enable client side verification. (Allow users to self-report over-censorship.)',
            array( $this, 'CSV_callback' ),
            'error-code-451-settings',
            'error_code_451_section_general'
        );
  /*
      Legacy settings fields, remove for cleanup or reuse if neccesary

      add_settings_field(
            'API_EMAIL',
            'Censor Email',
            array( $this, 'api_email_callback' ),
            'error-code-451-settings',
            'error_code_451_section_general'
        );*/

/*        add_settings_field(
            'HOST',
            'HOST URL or IP (no protocol, no trailing slash, i.e. blocked.example.io)',
            array( $this, 'host_callback' ),
            'error-code-451-settings',
            'error_code_451_section_general'
        );*/

  /*      add_settings_field(
            'GLOBAL',
            'Check this box if you REALLY REALLY like cake.',
            array( $this, 'global_callback' ),
            'error-code-451-settings',
            'error_code_451_section_general'
        );*/

    }
    /**
     * Sanitize each setting field as needed
     *
     * @param array $input Contains all settings fields as array keys
     */
    public function sanitize( $input ) {
    if( !empty( $input['REPORTING_URL'] ) )
        $input['REPORTING_URL'] = sanitize_text_field( $input['REPORTING_URL'] );
    if( !empty( $input['API_EMAIL'] ) )
        $input['API_EMAIL'] = sanitize_email( $input['API_EMAIL'] );
    if( !empty( $input['HOST'] ) )
        $input['HOST'] = sanitize_text_field( $input['HOST'] );

        return $input;
    }
    /**
     * Print the Section text
     */
    public function print_section_info() {
        print _e('<p>If you wish to report censorship instances to a public collector please add the URL here.</p> <p><strong>Example: https://registry.wirecdn.com/report</strong></p><p>Enabling this will send the following information to the collector:</p> <ul><li>- Site Home URL</url><li>- Date and time</li><li>- Blocked URL</li><li>- Description of blocking (If provided)</li><li>- URL of Authority requesting the blocking  (If provided)</li><li>- List of Countries where Content is Blocked</li><ul> ');
    }

    /**
     * Get the settings option array and print one of its values
     */
    public function api_key_callback() {
        printf(
            '<input type="text" id="REPORTING_URL" name="error_code_451_option_name[REPORTING_URL]" value="%s" class="regular-text ltr" />',
            esc_attr( $this->options['REPORTING_URL'])
        );
    }

    public function CSV_callback() {
        $options = get_option('error_code_451_option_name');
        echo '<input name="error_code_451_option_name[CSV]" id="CSV" type="checkbox" value="1" ' . checked( 1, $options['CSV'], false ) . ' /> yes';
    }

/*
  Legacy code, remove for cleanup or reuse if neccesary

 public function api_email_callback() {
        printf(
            '<input type="text" id="API_EMAIL" name="error_code_451_option_name[API_EMAIL]" value="%s" class="regular-text ltr" />',
            esc_attr( $this->options['API_EMAIL'])
        );


    public function host_callback() {
        printf(
            '<input type="text" id="HOST" name="error_code_451_option_name[HOST]" value="%s" class="regular-text ltr"  />',
            esc_attr( $this->options['HOST'])
        );
    }  }

    public function global_callback() {
        $options = get_option('error_code_451_option_name');
        echo '<input name="error_code_451_option_name[GLOBAL]" id="GLOBAL" type="checkbox" value="1" ' . checked( 1, $options['GLOBAL'], false ) . ' /> sure';
    }
    public function resultspage_status_callback($args) {
    $locale = $args['locale'];
    printf(
        '<input type="number" id="resultspage_'.$locale.'" name="error_code_451_option_name[resultspage_'.$locale.']" value="%s" class="regular-text ltr"  />',
        esc_attr( $this->options["resultspage_$locale"])
        );
    }  */
}

if( is_admin() )
    $error_code_451_settings_page = new errorCode451SettingsPage();


function error_451_report_blocking_data( $post_id, $post ) {

    /* Verify the nonce before proceeding. */
    if ( !isset( $_POST['error_451_blocking_nonce'] ) || !wp_verify_nonce( $_POST['error_451_blocking_nonce'], basename( __FILE__ ) ) )
        return $post_id;

    /* Get the post type object. */
    $post_type = get_post_type_object( $post->post_type );

    /* Check if the current user has permission to edit the post. */
    if ( !current_user_can( $post_type->cap->edit_post, $post_id ) )
        return $post_id;

    if ($_POST['error_451_blocking'] == "yes") {

      report_blocking(( isset( $_POST['error_451_blocking_authority'] ) ? sanitize_text_field( $_POST['error_451_blocking_authority'] ) : '' ),
                      ( isset( $_POST['error_451_blocking_countries'] ) ? sanitize_text_field( $_POST['error_451_blocking_countries'] ) : '' ),
                      ( isset( $_POST['error_451_blocking_description'] ) ? sanitize_text_field( $_POST['error_451_blocking_description'] ) : '' ),
                      get_permalink($post_id),
                      home_url()
      );
    }
}

add_action( 'save_post', 'error_451_report_blocking_data', 10, 2 );


function report_blocking ($authority, $countries, $description, $url, $siteurl) {
        global $cfg;

        if($countries == "") {
          $countries = "Global";
        }
        $options = get_option('error_code_451_option_name');
        if(!empty($options['REPORTING_URL'])) {
            $json_string = '{
                            "date": "'.date('c').'",
                            "creator": "'.$cfg['plugin_name'].'",
                            "version": "'.$cfg['plugin_version'].'",
                            "url": "'.$url.'",
                            "status": 451,
                            "statusText": "'.$description.'",
                            "blockedBy": "'.$siteurl.'",
                            "blockingAuthority": "'.$authority.'",
                            "blockedIn": "'.$countries.'"
                          }';
            $ch = curl_init($options['REPORTING_URL']);
            curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
            curl_setopt($ch, CURLOPT_POSTFIELDS, $json_string);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
            curl_setopt($ch, CURLOPT_HTTPHEADER, array(
                       'Content-Type: application/json',
                       'Content-Length: ' . strlen($json_string))
                        );

            return curl_exec($ch);
        }
    }
?>