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Reply to topic   Topic: Losing Post Data
Author
MarvinB



Joined: 15 Dec 2015
Posts: 6
Location: US

PostPosted: Tue 15 Dec '15 19:14    Post subject: Losing Post Data Reply with quote

I have an application on a JBoss application server with an Apache 2.2.26 server in front of it acting as a reverse proxy for HTTPS. The application has a large multi-part form which recently has been experiencing an intermittent drop of a single form field from the post data (not always the same field). We've verified that all of the data is being sent, but not being received by the application. And that the issue does not occur if we HTTP directly to the JBoss server (test setup). So, at this point we are fairly confident that the Apache server is the source of the data loss.

One additional bit of information is that since this is a multi-part form, the browser includes a boundary value between each form field and file when submitted. We've noted that the size of this boundary value varies and the form data that is being lost changes depending on the size of the boundary value. Oh, and this happens in for Internet Explorer and Firefox.

Any ideas as to what might be causing this data loss would be most appreciated. Thanks Smile
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James Blond
Moderator


Joined: 19 Jan 2006
Posts: 7371
Location: Germany, Next to Hamburg

PostPosted: Sat 26 Dec '15 10:37    Post subject: Reply with quote

It would help if you could post your reverse proxy config.

Does it depend on the size of the data?
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MarvinB



Joined: 15 Dec 2015
Posts: 6
Location: US

PostPosted: Mon 04 Jan '16 17:45    Post subject: Reply with quote

I'll try to get the reverse proxy config posted soon. However, in response to your question about the size of the data. Unfortunately the answer is that it is somewhat dependent on the size of the data. The exact same data being sent will not always result in a data item being dropped. However, the exact same data sent with different boundary values does result in a different data item being dropped. This is a very strange, but also very repeatable problem.
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MarvinB



Joined: 15 Dec 2015
Posts: 6
Location: US

PostPosted: Mon 11 Jan '16 22:29    Post subject: Reply with quote

The issue seems to be similar to this old bug, https://bz.apache.org/bugzilla/show_bug.cgi?id=37145 . I'm wondering if its possible that the issue has reappeared?
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MarvinB



Joined: 15 Dec 2015
Posts: 6
Location: US

PostPosted: Tue 12 Jan '16 20:04    Post subject: Reply with quote

Not sure if this is what you needed to see for the reverse proxy setup, but hopefully this will work:

Code:

ProxyRequests Off
ProxyPreserveHost On
ProxyPass / ajp://app.com:8009/
ProxyPassReverse / ajp://app.com:8009/
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MarvinB



Joined: 15 Dec 2015
Posts: 6
Location: US

PostPosted: Thu 21 Jan '16 18:34    Post subject: UPDATE Reply with quote

Learned how to monitor the number of bytes being received at the ajp port on the JBoss server. Ran a few tests and the number of bytes being sent from the browser match the number of bytes being received at the ajp port.

Could this be a chunk encoding issue?
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James Blond
Moderator


Joined: 19 Jan 2006
Posts: 7371
Location: Germany, Next to Hamburg

PostPosted: Mon 25 Jan '16 16:33    Post subject: Reply with quote

Ecoding? Might be. I'm not sure since the ajp is a binary bi-directional protocol. Chunked enconding is used with keep alive in http/1.1. I don't know if ajp offers that feature.
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MarvinB



Joined: 15 Dec 2015
Posts: 6
Location: US

PostPosted: Fri 17 Jun '16 23:03    Post subject: Issue has been resolved Reply with quote

We recently updated our SSL protocol from TLSv1 to TLSv1.2 . The problem went away with the update. We tested and verified that returning to TLSv1 caused the issue to reappear. No idea why the protocol upgrade resolved the issue, just very happy that the very annoying problem has gone away.

Anyone have any ideas as to why the protocol upgrade might have resolved the issue?
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