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

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.

1 files changed, 163 insertions, 7 deletions

diff --git a/mod/salmon.php b/mod/salmon.php
index d68c74658..7ae29aafe 100644
--- a/mod/salmon.php
+++ b/mod/salmon.php
@@ -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'));
+
+	$feedxml = $tpl . $base . '</feed>';
+
+	if($debugging) {
+		file_put_contents('salmon.out', 'Processed feed: ' . $feedxml . "\n", FILE_APPEND);
+	}
+
+	// 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);
+	}
 
-	$xml = $tpl . $base . '</feed>';
+	// Once we have the author URI, go to the web and find their public key
 
-salmon_return(500); // until the handler is finished
+	if($debugging) {
+		file_put_contents('salmon.out', "\n" . 'Fetching key for ' . $author_link . "\n", FILE_APPEND);
+	}
 
-//	consume_salmon($xml,$importer);
+	$key = get_salmon_key($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);
 }
 
 
 
+