From: martinlanghoff <martinlanghoff>
Date: Thu, 4 Jan 2007 03:36:24 +0000 (+0000)
Subject: mnet/xmlrpc/client & parser: Diff time between servers and break if it's
X-Git-Url: http://git.mjollnir.org/gw?a=commitdiff_plain;h=f0e4c2701ce7edfd9aa5c7d9b9988781c81ecb53;p=moodle.git

mnet/xmlrpc/client & parser: Diff time between servers and break if it's

too large


Author: Donal McMullan <donal@catalyst.net.nz>
---

diff --git a/mnet/xmlrpc/client.php b/mnet/xmlrpc/client.php
index 245d3a9cb2..85079177c8 100644
--- a/mnet/xmlrpc/client.php
+++ b/mnet/xmlrpc/client.php
@@ -174,9 +174,13 @@ class mnet_xmlrpc_client {
         curl_setopt($ch, CURLOPT_POSTFIELDS, $rq);
         curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: text/xml charset=UTF-8"));
 
+        $timestamp_send    = time();
         $this->rawresponse = curl_exec($ch);
+        $timestamp_receive = time();
+
         if ($this->rawresponse == false) {
             $this->error[] = array(curl_errno($ch), curl_error($ch));
+            return false;
         }
 
         $crypt_parser = new mnet_encxml_parser();
@@ -211,6 +215,32 @@ class mnet_xmlrpc_client {
             return false;
         }
 
+        // Margin of error is the time it took the request to complete.
+        $margin_of_error  = $timestamp_receive - $timestamp_send;
+
+        // Guess the time gap between sending the request and the remote machine
+        // executing the time() function. Marginally better than nothing.
+        $hysteresis       = ($margin_of_error) / 2;
+
+        $remote_timestamp = $sig_parser->remote_timestamp - $hysteresis;
+        $time_offset      = $remote_timestamp - $timestamp_send;
+        if ($time_offset > 0) {
+            $result = get_field('config_plugins', 'value', 'plugin', 'mnet', 'name', 'drift_threshold');
+            if(empty($result)) {
+                // We decided 15 seconds was a pretty good arbitrary threshold
+                // for time-drift between servers, but you can customize this in
+                // the config_plugins table. It's not advised though.
+                set_config('drift_threshold', 15, 'mnet');
+                $threshold = 15;
+            } else {
+                $threshold = $result;
+            }
+            if ($time_offset > $threshold) {
+                $this->error[] = 'Time gap with '.$mnet_peer->name.' ('.$time_offset.' seconds) is greater than the permitted maximum of '.$threshold.' seconds';
+                return false;
+            }
+        }
+
         $this->xmlrpcresponse = base64_decode($sig_parser->data_object);
         $this->response       = xmlrpc_decode($this->xmlrpcresponse);
         curl_close($ch);
diff --git a/mnet/xmlrpc/xmlparser.php b/mnet/xmlrpc/xmlparser.php
index 97069b5d40..af958d2f8a 100644
--- a/mnet/xmlrpc/xmlparser.php
+++ b/mnet/xmlrpc/xmlparser.php
@@ -35,6 +35,7 @@ class mnet_encxml_parser {
 
         $this->tag_number        = 0; // Just a unique ID for each tag
         $this->digest            = '';
+        $this->remote_timestamp  = '';
         $this->remote_wwwroot    = '';
         $this->signature         = '';
         $this->data_object       = '';
@@ -130,6 +131,9 @@ class mnet_encxml_parser {
             case 'RETRIEVALMETHOD':
                 $this->key_URI = $attrs['URI'];
                 break;
+            case 'TIMESTAMP':
+                $handler = 'parse_timestamp';
+                break;
             case 'WWWROOT':
                 $handler = 'parse_wwwroot';
                 break;
@@ -144,6 +148,18 @@ class mnet_encxml_parser {
         return true;
     }
 
+    /**
+     * Add the next chunk of character data to the remote_timestamp string
+     *
+     * @param   mixed   $parser The XML parser
+     * @param   string  $data   The content of the current tag (1024 byte chunk)
+     * @return  bool            True
+     */
+    function parse_timestamp($parser, $data) {
+        $this->remote_timestamp .= $data;
+        return true;
+    }
+
     /**
      * Add the next chunk of character data to the cipher string for that tag
      *