streams/Zotlabs/Module/Activity.php

<?php
namespace Zotlabs\Module;

use Zotlabs\Web\Controller;
use Zotlabs\Lib\ActivityStreams;
use Zotlabs\Lib\Activity as ZlibActivity;


class Activity extends Controller {

	function init() {

		if (ActivityStreams::is_as_request()) {
			$item_id = argv(1);

			if (! $item_id) {
				return;
			}

			$item_normal = " and item.item_hidden = 0 and item.item_type = 0 and item.item_unpublished = 0 
				and item.item_delayed = 0 and item.item_blocked = 0 ";

			// if passed an owner_id of 0, we force "guest access" or observer checking
			$sql_extra = item_permissions_sql(0);

			$r = q("select * from item where uuid = '%s' $item_normal $sql_extra limit 1",
				dbesc($item_id)
			);
			if (! $r) {
				$r = q("select * from item where uuid = '%s' $item_normal limit 1",
					dbesc($item_id)
				);

				if($r) {
					http_status_exit(403, 'Forbidden');
				}
				http_status_exit(404, 'Not found');
			}

			xchan_query($r,true);
			$items = fetch_post_tags($r,true);

			$channel = channelx_by_n($items[0]['uid']);

			$x = array_merge( ['@context' => [
				ACTIVITYSTREAMS_JSONLD_REV,
				'https://w3id.org/security/v1',
				z_root() . ZOT_APSCHEMA_REV
				]], ZlibActivity::encode_activity($items[0]));



			$headers = [];
			$headers['Content-Type'] = 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' ;
			$x['signature'] = LDSignatures::sign($x,$channel);
			$ret = json_encode($x, JSON_UNESCAPED_SLASHES);
			$headers['Digest'] = HTTPSig::generate_digest_header($ret);
			$headers['(request-target)'] = strtolower($_SERVER['REQUEST_METHOD']) . ' ' . $_SERVER['REQUEST_URI'];

			$h = HTTPSig::create_sig($headers,$channel['channel_prvkey'],channel_url($channel));
			HTTPSig::set_headers($h);
			echo $ret;
			killme();

		}

	}

}