From 4ad1468165b80f67439399e36688d36944996312 Mon Sep 17 00:00:00 2001
From: Oren Hurvitz
Date: Sun, 5 Jul 2015 16:05:01 +0300
Subject: Better handling of invalid XML: a) prevent infinite loop on EOF; b)
 better logging

If the XML was truncated for some reason then ExecuteReadProcessors() would get into an infinite loop, using high CPU. Now it detects EOF (and several other error cases) and aborts.

The rest of the changes just improve logging of XML in case of errors, so that we can see what the bad XML is.
---
 .../External/ExternalRepresentationUtils.cs        | 40 +++++++++++++++++-----
 1 file changed, 32 insertions(+), 8 deletions(-)

(limited to 'OpenSim/Framework/Serialization')

diff --git a/OpenSim/Framework/Serialization/External/ExternalRepresentationUtils.cs b/OpenSim/Framework/Serialization/External/ExternalRepresentationUtils.cs
index 1254086..55640ac 100644
--- a/OpenSim/Framework/Serialization/External/ExternalRepresentationUtils.cs
+++ b/OpenSim/Framework/Serialization/External/ExternalRepresentationUtils.cs
@@ -27,6 +27,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Reflection;
 using System.Xml;
@@ -47,7 +48,7 @@ namespace OpenSim.Framework.Serialization.External
         /// Populate a node with data read from xml using a dictinoary of processors
         /// </summary>
         /// <param name="nodeToFill"></param>
-        /// <param name="processors">/param>
+        /// <param name="processors"></param>
         /// <param name="xtr"></param>
         /// <returns>true on successful, false if there were any processing failures</returns>
         public static bool ExecuteReadProcessors<NodeType>(
@@ -57,10 +58,10 @@ namespace OpenSim.Framework.Serialization.External
                 nodeToFill,
                 processors,
                 xtr,
-                (o, name, e)
-                    => m_log.DebugFormat(
-                        "[ExternalRepresentationUtils]: Exception while parsing element {0}, continuing.  Exception {1}{2}",
-                        name, e.Message, e.StackTrace));
+                (o, nodeName, e) => {
+                    m_log.Debug(string.Format("[ExternalRepresentationUtils]: Error while parsing element {0} ",
+                        nodeName), e);
+                });
         }
 
         /// <summary>
@@ -80,18 +81,22 @@ namespace OpenSim.Framework.Serialization.External
             Action<NodeType, string, Exception> parseExceptionAction)
         {
             bool errors = false;
+            int numErrors = 0;
+
+            Stopwatch timer = new Stopwatch();
+            timer.Start();
 
             string nodeName = string.Empty;
             while (xtr.NodeType != XmlNodeType.EndElement)
             {
                 nodeName = xtr.Name;
 
-//                        m_log.DebugFormat("[ExternalRepresentationUtils]: Processing: {0}", nodeName);
+                // m_log.DebugFormat("[ExternalRepresentationUtils]: Processing node: {0}", nodeName);
 
                 Action<NodeType, XmlReader> p = null;
                 if (processors.TryGetValue(xtr.Name, out p))
                 {
-//                            m_log.DebugFormat("[ExternalRepresentationUtils]: Found {0} processor, nodeName);
+                    // m_log.DebugFormat("[ExternalRepresentationUtils]: Found processor for {0}", nodeName);
 
                     try
                     {
@@ -101,6 +106,18 @@ namespace OpenSim.Framework.Serialization.External
                     {
                         errors = true;
                         parseExceptionAction(nodeToFill, nodeName, e);
+                        
+                        if (xtr.EOF)
+                        {
+                            m_log.Debug("[ExternalRepresentationUtils]: Aborting ExecuteReadProcessors due to unexpected end of XML");
+                            break;
+                        }
+                        
+                        if (++numErrors == 10)
+                        {
+                            m_log.Debug("[ExternalRepresentationUtils]: Aborting ExecuteReadProcessors due to too many parsing errors");
+                            break;
+                        }
 
                         if (xtr.NodeType == XmlNodeType.EndElement)
                             xtr.Read();
@@ -108,9 +125,16 @@ namespace OpenSim.Framework.Serialization.External
                 }
                 else
                 {
-                    // m_log.DebugFormat("[LandDataSerializer]: caught unknown element {0}", nodeName);
+                    // m_log.DebugFormat("[ExternalRepresentationUtils]: found unknown element \"{0}\"", nodeName);
                     xtr.ReadOuterXml(); // ignore
                 }
+
+                if (timer.Elapsed.TotalSeconds >= 60)
+                {
+                    m_log.Debug("[ExternalRepresentationUtils]: Aborting ExecuteReadProcessors due to timeout");
+                    errors = true;
+                    break;
+                }
             }
 
             return errors;
-- 
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