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https://issues.apache.org/jira/browse/HTTPCORE-242?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12934649#action_12934649
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Michael Poindexter commented on HTTPCORE-242:
---------------------------------------------
Looking at the changes it does not seem like there is any way for code using
AsyncNHttpClientHandler to detect if the connection is due to be closed due to
an early response. Maybe I am doing something wrong, but I make my decision
about whether to try to reuse the connection in the handleResponse callback (my
use case is simple, so I have no need of a connection pool). Would it make
more sense to close the connection before execHandler.handleResponse(response,
context) so that code in the event handler could test if the connection was
closed?
> 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
> Fix For: 4.1.1
>
> Attachments: httcore-quickresponse.pcap, HTTPCORE-242.patch,
> httpcore-connection-reuse-bug-fixed2.zip, httpcore.log
>
>
> 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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