GitHub user bgaff opened a pull request:
https://github.com/apache/trafficserver/pull/351
TS-4042: Add feature to buffer request body before making downstream
requests
We need a way to examine the request body without making a downstream
request, this feature has many use cases including:
- Ability to buffer the body and ensure a full post is received before
committing downstream resources.
- Ability to choose an origin based on request body
- Ability to do request content filtering such as a WAF might provide
before the origin is involved.
Today you have two options to inspect a request body:
1) Transformations: the problem with transformations is that you only
start receiving the request bytes after a sink has been established, which in
this case is the downstream origin.
2) Create an intercept and use fetch apis to then send the downstream
request: while this technically works it turns out to be a ton of code and is
in general pretty problematic, we actually tried this approach for a while and
had nothing but problems with it.
We feel it would be ideal if we could intercept the body without breaking
the normal ATS state flow. There used to exist code (and it's still in the core
just #ifdefed out) to drain the request body. I use that code as the basis for
this request buffering code. We added APIs to both the C and C++ APIs so that
this request buffering can be enabled from a plugin and the plugin can inspect
the body as chunks arrive or when it's complete. We've included an example
plugin that will error a transaction if a minimum rate of transfer is not
maintained. We've been using a very similar method in the core for buffer
request bodies for several months without issues so the code that is new (for
us) is basically all the API stuff.
I'm confident that this feature will bring plenty of questions / feedback,
so let's get that party started. @zwoop @SolidWallOfCode @jpeach @sudheerv : if
you have time would you mind commenting / reviewing.
cc. @jacksontj @zizhong @canselcik
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/bgaff/trafficserver TS-4042
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/trafficserver/pull/351.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #351
----
commit 6d0acd528cd09d17c92e5097710c1f192ef1f584
Author: Brian Geffon <bri...@apache.org>
Date: 2015-11-20T17:37:12Z
TS-4042: Add feature to buffer request body before making downstream
requests
commit 2b806a80ab3e0447d5b882b8b00afbeb59d6c8e1
Author: Brian Geffon <bri...@apache.org>
Date: 2015-11-20T17:43:44Z
TS-4042: Add feature to buffer request body before making downstream
requests: example C plugin.
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