Friendica Communications Platform (please note that this is a clone of the repository at github, issues are handled there) https://friendi.ca
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<?php
// There is a lot of debug stuff in here because this is quite a
// complicated process to try and sort out.
require_once('include/salmon.php');
require_once('library/simplepie/simplepie.inc');
function salmon_return($val) {
if($val >= 400)
$err = 'Error';
if($val >= 200 && $val < 300)
$err = 'OK';
logger('mod-salmon returns ' . $val);
header($_SERVER["SERVER_PROTOCOL"] . ' ' . $val . ' ' . $err);
killme();
}
function salmon_post(&$a) {
$xml = file_get_contents('php://input');
logger('mod-salmon: new salmon ' . $xml);
$nick = (($a->argc > 1) ? notags(trim($a->argv[1])) : '');
$mentions = (($a->argc > 2 && $a->argv[2] === 'mention') ? true : false);
$r = q("SELECT * FROM `user` WHERE `nickname` = '%s' LIMIT 1",
dbesc($nick)
);
if(! count($r))
salmon_return(500);
$importer = $r[0];
// parse the xml
$dom = simplexml_load_string($xml,'SimpleXMLElement',0,NAMESPACE_SALMON_ME);
// figure out where in the DOM tree our data is hiding
if($dom->provenance->data)
$base = $dom->provenance;
elseif($dom->env->data)
$base = $dom->env;
elseif($dom->data)
$base = $dom;
if(! $base) {
logger('mod-salmon: unable to locate salmon data in xml ');
salmon_return(400);
}
// Stash the signature away for now. We have to find their key or it won't be good for anything.
$signature = base64url_decode($base->sig);
// unpack the data
// strip whitespace so our data element will return to one big base64 blob
$data = str_replace(array(" ","\t","\r","\n"),array("","","",""),$base->data);
// stash away some other stuff for later
$type = $base->data[0]->attributes()->type[0];
$keyhash = $base->sig[0]->attributes()->keyhash[0];
$encoding = $base->encoding;
$alg = $base->alg;
// If we're talking to status.net or one of their ilk, they aren't following the magic envelope spec
// and only signed the data element. We'll be nice and let them validate anyway.
$stnet_signed_data = $data;
$signed_data = $data . '.' . base64url_encode($type) . '.' . base64url_encode($encoding) . '.' . base64url_encode($alg);
// decode the data
$data = base64url_decode($data);
// Remove the xml declaration
$data = preg_replace('/\<\?xml[^\?].*\?\>/','',$data);
// Create a fake feed wrapper so simplepie doesn't choke
$tpl = get_markup_template('fake_feed.tpl');
$base = substr($data,strpos($data,'<entry'));
$feedxml = $tpl . $base . '</feed>';
logger('mod-salmon: Processed feed: ' . $feedxml);
// Now parse it like a normal atom feed to scrape out the author URI
$feed = new SimplePie();
$feed->set_raw_data($feedxml);
$feed->enable_order_by_date(false);
$feed->init();
logger('mod-salmon: Feed parsed.');
if($feed->get_item_quantity()) {
foreach($feed->get_items() as $item) {
$author = $item->get_author();
$author_link = unxmlify($author->get_link());
break;
}
}
if(! $author_link) {
logger('mod-salmon: Could not retrieve author URI.');
salmon_return(400);
}
// Once we have the author URI, go to the web and try to find their public key
logger('mod-salmon: Fetching key for ' . $author_link );
$key = get_salmon_key($author_link,$keyhash);
if(! $key) {
logger('mod-salmon: Could not retrieve author key.');
salmon_return(400);
}
// Setup RSA stuff to verify the signature
set_include_path(get_include_path() . PATH_SEPARATOR . 'library' . PATH_SEPARATOR . 'phpsec');
require_once('library/phpsec/Crypt/RSA.php');
$key_info = explode('.',$key);
$m = base64url_decode($key_info[1]);
$e = base64url_decode($key_info[2]);
logger('mod-salmon: key details: ' . print_r($key_info,true));
$rsa = new CRYPT_RSA();
$rsa->signatureMode = CRYPT_RSA_SIGNATURE_PKCS1;
$rsa->setHash('sha256');
$rsa->modulus = new Math_BigInteger($m, 256);
$rsa->k = strlen($rsa->modulus->toBytes());
$rsa->exponent = new Math_BigInteger($e, 256);
// We should have everything we need now. Let's see if it verifies.
// If it fails with the proper data format, try again using just the data
// (e.g. status.net)
$verify = $rsa->verify($signed_data,$signature);
if(! $verify) {
logger('mod-salmon: message did not verify using protocol. Trying statusnet hack.');
$verify = $rsa->verify($stnet_signed_data,$signature);
}
if(! $verify) {
logger('mod-salmon: Message did not verify. Discarding.');
salmon_return(400);
}
logger('mod-salmon: Message verified.');
/*
*
* If we reached this point, the message is good. Now let's figure out if the author is allowed to send us stuff.
*
*/
$r = q("SELECT * FROM `contact` WHERE `network` = 'stat' AND ( `url` = '%s' OR `alias` = '%s')
AND `uid` = %d LIMIT 1",
dbesc($author_link),
dbesc($author_link),
intval($importer['uid'])
);
if(! count($r)) {
logger('mod-salmon: Author unknown to us.');
}
// is this a follower? Or have we ignored the person?
// If so we can not accept this post.
if((count($r)) && (($r[0]['readonly']) || ($r[0]['rel'] == REL_VIP)) {
logger('mod-salmon: Ignoring this author.');
salmon_return(202);
// NOTREACHED
}
require_once('include/items.php');
// Placeholder for hub discovery. We shouldn't find any hubs
// since we supplied the fake feed header - and it doesn't have any.
$hub = '';
/**
*
* anti-spam measure: consume_feed will accept a follow activity from
* this person (and nothing else) if there is no existing contact record.
*
*/
$contact_rec = ((count($r)) ? $r[0] : null);
consume_feed($feedxml,$importer,$contact_rec,$hub);
salmon_return(200);
}