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https://issues.apache.org/jira/browse/HTTPCORE-242?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Poindexter updated HTTPCORE-242:
----------------------------------------

    Attachment: httcore-quickresponse.pcap

PCAP of the problem

> NullPointerException in AsyncNHttpClientHandler  when server sends reply 
> before request is fully written.
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: HTTPCORE-242
>                 URL: https://issues.apache.org/jira/browse/HTTPCORE-242
>             Project: HttpComponents HttpCore
>          Issue Type: Bug
>          Components: HttpCore NIO
>    Affects Versions: 4.1
>         Environment: Server:  IIS/7.5 with NTLM authentication.
>            Reporter: Michael Poindexter
>         Attachments: httcore-quickresponse.pcap, 
> httpcore-connection-reuse-bug.zip
>
>
> I'm seeing a problem with AsyncNHttpClientHandler in v4.1 of HttpCore.  When 
> I submit a number of requests simultaneously or a single POST with a large 
> body to a server using NTLM authentication, I get this exception:
> Caused by: java.lang.NullPointerException
> at 
> org.apache.http.nio.protocol.AsyncNHttpClientHandler.outputReady(AsyncNHttpClientHandler.java:268)
> at 
> org.apache.http.nio.protocol.BufferingHttpClientHandler.outputReady(BufferingHttpClientHandler.java:118)
> at 
> org.apache.http.impl.nio.DefaultNHttpClientConnection.produceOutput(DefaultNHttpClientConnection.java:207)
> at 
> org.apache.http.impl.nio.ssl.SSLClientIOEventDispatch.outputReady(SSLClientIOEventDispatch.java:245)
> at 
> com.qumu.cxf.rt.transport.ahttp.MultiProtocolIOEventDispatch.outputReady(MultiProtocolIOEventDispatch.java:49)
> at 
> org.apache.http.impl.nio.reactor.BaseIOReactor.writable(BaseIOReactor.java:185)
> at 
> org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:338)
> at 
> org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:315)
> at 
> org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:275)
> at 
> org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:104)
> at 
> org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:542)
> at java.lang.Thread.run(Thread.java:680)
> The server I am connecting to is IIS/7.5. I am using NTLM authentication 
> (with JCIFS), so I need to keep the connection alive through several round 
> trips as the NTLM message exchange occurs.
> I dug into the HttpCore code, and here is my analysis of what is occurring:
> 1.) AsyncNHttpClientHandler.connect calls requestReady to send the initial 
> request.  This sets the request on the connection, and the connection starts 
> writing the request line in response to write events.
> 2.) The server receives the request line and responds immediately with a 401 
> Unauthorized.  At this point the POST body has not been fully sent to the 
> server.
> 3.) AsyncNHttpClientHandler.inputReady is called with the response from the 
> server.  At this point processResponse is called, and my code executes.  I 
> detect that the request needs authentication and I need to retransmit my 
> request with an auth header, so my ConnectionReuseStrategy says to keep the 
> connection alive.
> 4.) When control returns from my code, the code in processResponse calls 
> connState.resetOutput, clearing the entity and request in connState.  There 
> is still output from the POST body pending.
> 5.)  processResponse calls conn.requestOutput to reenable write events since 
> the connection is not to be closed.
> 6.)  A write event happens, and DefaultNHttpClientConnection.produceOutput is 
> called.  Since the output from the initial request never finished, 
> contentEncoder is not null and so AsyncNHttpClientHandler.outputReady is 
> called instead of requestReady.  Since connState was reset, the entity is 
> null and this NPE happens.
> I copied the code of AsyncNHttpClientHandler and added a conn.suspendInput() 
> call in requestReady:
>            if (entityReq != null && entityReq.expectContinue()) {
>                .....
>            } else {
>            conn.suspendInput();
>            }
> and a conn.requestInput call in outputReady:
>            entity.produceContent(encoder, conn);
>            if(encoder.isCompleted()) {
>            conn.requestInput();
>            }
> and this seemed to resolve the issue by not allowing the request and response 
> to overlap, but I'm not sure this is the best way to fix it.

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