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magic-envelope verification, status.net appears to do it wrong.

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Ultimately we need to do it right (or why bother having a spec?),
and fallback to doing it wrong if we're talking to a broken system - which
ironically seems to include most of the federated social web projects.
This commit is contained in:
Mike Macgirvin 2010-10-21 04:53:43 -07:00
commit 5edee3c4d1
8 changed files with 354 additions and 27 deletions
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170
mod/salmon.php
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@ -1,5 +1,15 @@
<?php
// TODO: pass keyhash to key discovery
// add relevant contacts so they can use this
// 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('simplepie/simplepie.inc');
function salmon_return($val) {
if($val >= 500)
@ -18,7 +28,7 @@ function salmon_post(&$a) {
$debugging = get_config('system','debugging');
if($debugging)
file_put_contents('salmon.out',$xml,FILE_APPEND);
file_put_contents('salmon.out','New Salmon: ' . $xml . "\n",FILE_APPEND);
$nick = (($a->argc > 1) ? notags(trim($a->argv[1])) : '');
$mentions = (($a->argc > 2 && $a->argv[2] === 'mention') ? true : false);
@ -31,22 +41,168 @@ function salmon_post(&$a) {
$importer = $r[0];
require_once('include/items.php');
// parse the xml
$dom = simplexml_load_string($xml,'SimpleXMLElement',0,NAMESPACE_SALMON_ME);
if($debugging)
file_put_contents('salmon.out', "\n" . print_r($dom,true) . "\n" , FILE_APPEND);
// 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(! $base) {
if($debugging)
file_put_contents('salmon.out', "\n" . 'Unable to find salmon data in XML' . "\n" , FILE_APPEND);
salmon_return(500);
}
// 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);
if($debugging)
file_put_contents('salmon.out', "\n" . 'Encoded Signature: ' . $base->sig . "\n" , FILE_APPEND);
// unpack our data element.
// strip whitespace
$data = str_replace(array(" ","\t","\r","\n"),array("","","",""),$base->data);
$type = $base->data[0]->attributes()->type[0];
$encoding = $base->encoding;
$alg = $base->alg;
$signed_data = $data;
// . '.' . base64url_encode($type) . '.' . base64url_encode($encoding) . '.' . base64url_encode($alg);
// decode it
$data = base64url_decode($data);
if($debugging)
file_put_contents('salmon.out', "\n" . 'Signed data:>>>' . $signed_data . "<<<\n" , FILE_APPEND);
// Remove the xml declaration
$data = preg_replace('/\<\?xml[^\?].*\?\>/','',$data);
// Create a fake feed wrapper so simplepie doesn't choke
$tpl = load_view_file('view/atom_feed.tpl');
$tpl = load_view_file('view/fake_feed.tpl');
$base = substr($xml,strpos($xml,'<entry'));
$base = substr($data,strpos($data,'<entry'));
$xml = $tpl . $base . '</feed>';
$feedxml = $tpl . $base . '</feed>';
salmon_return(500); // until the handler is finished
if($debugging) {
file_put_contents('salmon.out', 'Processed feed: ' . $feedxml . "\n", FILE_APPEND);
}
// consume_salmon($xml,$importer);
// 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);
$feed->init();
if($debugging) {
file_put_contents('salmon.out', "\n" . 'Feed parsed.' . "\n", FILE_APPEND);
}
if($feed->get_item_quantity()) {
foreach($feed->get_items() as $item) {
$author = $item->get_author();
$author_link = unxmlify($author->get_link());
break;
}
}
if(! $author_link) {
if($debugging)
file_put_contents('salmon.out',"\n" . 'Could not retrieve author URI.' . "\n", FILE_APPEND);
salmon_return(500);
}
// Once we have the author URI, go to the web and find their public key
if($debugging) {
file_put_contents('salmon.out', "\n" . 'Fetching key for ' . $author_link . "\n", FILE_APPEND);
}
$key = get_salmon_key($author_link,$keyhash);
if(! $key) {
if($debugging)
file_put_contents('salmon.out',"\n" . 'Could not retrieve author key.' . "\n", FILE_APPEND);
salmon_return(500);
}
// Setup RSA stuff to verify the signature
set_include_path(get_include_path() . PATH_SEPARATOR . 'phpsec');
require_once('phpsec/Crypt/RSA.php');
$key_info = explode('.',$key);
$m = base64url_decode($key_info[1]);
$e = base64url_decode($key_info[2]);
if($debugging)
file_put_contents('salmon.out',"\n" . print_r($key_info,true) . "\n", FILE_APPEND);
$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.
$verify = $rsa->verify($signed_data,$signature);
if(! $verify) {
if($debugging)
file_put_contents('salmon.out',"\n" . 'Message did not verify. Discarding.' . "\n", FILE_APPEND);
salmon_return(500);
}
if($debugging)
file_put_contents('salmon.out',"\n" . 'Message verified.' . "\n", FILE_APPEND);
/*
*
* If we reached this point, the message is good. Now let's figure out if the author is allowed to send us stuff.
*
*/
$r = q("SELECT * FROM `contact` WHERE `network` = 'stat' AND `lrdd` = '%s' AND `uid` = %d LIMIT 1",
dbesc($author_link),
intval($importer['uid'])
);
if(! count($r)) {
if($debugging)
file_put_contents('salmon.out',"\n" . 'Author unknown to us.' . "\n", FILE_APPEND);
salmon_return(500);
}
require_once('include/items.php');
$hub = '';
consume_feed($feedxml,$importer,$r[0],$hub);
salmon_return(200);
}