[jetty-discuss] [ jetty-Bugs-1503333 ] ArrayIndexOutOfBoundsException error + suggested fix.

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Bugs item #1503333, was opened at 2006-06-09 16:30
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Category: Other
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Trudi Ersvaer (trudiersvaer)
Assigned to: Nobody/Anonymous (nobody)
Summary: ArrayIndexOutOfBoundsException error + suggested fix.

Initial Comment:
My environment...
 
jetty-5.1.11RC0
Windows XP
Java 1.4.2_09

I have created a custom handler for Jetty which 
proxies a request onto a different endpoint.  My 
handler is the only one that is configured.  After it 
runs "handled" is set to true.  

The proxy code is created with HTTPURLConnection.  I 
am basically copying the request that the handler gets 
to the HTTPURLConnection's output stream (using 
org.mortbay.util.IO.copy()).  I also copy the headers 
etc.  

When I get the response I do the opposite.

The only other thing the handler does is add headers.

A number of messages are sent before the error 
occurs.  The error occurs during the copying of one of 
the responses from the proxied endpoint to Jetty's 
response.  The stack I'm getting is...

java.lang.ArrayIndexOutOfBoundsException
	at java.lang.System.arraycopy(Native Method)
	at 
org.mortbay.util.ByteBufferOutputStream.write
(ByteBufferOutputStream.java:198)
	at org.mortbay.http.BufferedOutputStream.write
(BufferedOutputStream.java:153)
	at org.mortbay.http.HttpOutputStream.write
(HttpOutputStream.java:423)
	…My handler stack
	at org.mortbay.http.HttpContext.handle
(HttpContext.java:1530)
	at org.mortbay.http.HttpContext.handle
(HttpContext.java:1482)
	at org.mortbay.http.HttpServer.service
(HttpServer.java:909)
	at org.mortbay.http.HttpConnection.service
(HttpConnection.java:820)
	at org.mortbay.http.HttpConnection.handleNext
(HttpConnection.java:986)
	at org.mortbay.http.HttpConnection.handle
(HttpConnection.java:837)
	at 
org.mortbay.http.SocketListener.handleConnection
(SocketListener.java:245)
	at org.mortbay.util.ThreadedServer.handle
(ThreadedServer.java:357)
	at org.mortbay.util.ThreadPool$PoolThread.run
(ThreadPool.java:534)

It is quiet a complicated set of requests that I send 
to get the error to occur so I haven't included a test 
case.  Instead, I think I know where the problem is 
(if need be, I can create a test case for you...but it 
is a bit of work).   

It looks like there might be a bug in 
BufferedOutputStream.resetStream().  The current code 
is:

super.reset(_httpMessageWriter.capacity());
_commited=false;

I think the call to the reset() method of 
ByteBufferedOutputStream is the problem. 

ByteBufferedOutputStream.reset is coded as: 

public void reset(int reserve)
{
    _preReserve=reserve;
    _pos=_preReserve;
    _start=_preReserve;
}

I think the parameter is meant to be a new value of 
the preReserve. However, the value isn't checked 
perhaps a call to ensureReserve() should appear 
there?).  In my case, the parameter being passed as 
over 9000, when the current buffer size was just over 
8000. 

In BufferedOutputStream, I think the call to reset is 
being passed the current capacity of the message 
writer...rather than the desired reserve?

I think the reset method of ByteBufferOutputStream 
could be removed altogether. It is only used in two 
places, and in both cases it would be equally easy to 
call the resetStream method instead. 

In summary, the recommended changes are: 

The BufferedOutputStream.resetStream() method code 
becomes: 

super.resetStream();    
// replacing super.reset (_httpMessageWriter.capacity
());
_commited=false;

while BufferedOutputStream.flush() finally clause 
becomes: 

finally
{
    super.resetStream();    
    // replacing reset(_preReserve);
}

Attached is the file with my recommended changes.  See 
lines 211 & 240.

Thanks in advance.

Trudi.

Also, my server is started with the following 
configuration...

<?xml version="1.0"?>
<!DOCTYPE Configure PUBLIC "-//Mort Bay 
Consulting//DTD 
Configure//EN" "http://jetty.mortbay.org/configure.dtd"
>

<Configure class="org.mortbay.jetty.Server">

  <Call name="addListener">
    <Arg>
      <New class="org.mortbay.http.SocketListener">
        <Set name="Port"><SystemProperty 
name="jetty.port" default="6666"/></Set>
	    <Set name="Host">localhost</Set>
	    <Set name="PoolName">P1</Set>
        <Set name="MinThreads">20</Set>
        <Set name="MaxThreads">200</Set>
        <Set name="lowResources">50</Set>
        <Set name="MaxIdleTimeMs">30000</Set>
        <Set name="LowResourcePersistTimeMs">2000</Set>
        <Set name="acceptQueueSize">0</Set>
        <Set name="ConfidentialPort">8443</Set>
        <Set name="IntegralPort">8443</Set>
      </New>
    </Arg>
  </Call>

  <Call name="addContext">
    <Arg>
        <New class="org.mortbay.http.HttpContext">
            <Set name="ContextPath">/</Set>
        </New>
    </Arg>
    <Call name="addHandler">
        <Arg>
            <New class="com.myHandler"/>
        </Arg>
    </Call>
  </Call>

</Configure>


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