Send headers in output body filter ?
mdounin at mdounin.ru
Fri Mar 26 19:02:29 UTC 2021
On Fri, Mar 26, 2021 at 06:05:27PM +0100, Alfred Sawaya wrote:
> I am developping a nginx C module that aims to modify the backend
> response (handled by the proxy module) in order to redact specified strings.
> I have a working module, but I am stuck on a case where the module modfy
> the length of the backend response. As the output header filter is
> called before the output body filter, the content-length is already sent
> when the module get the backend response and modifies it.
> Is there any normal way to workaround this? I would like to avoid
> writing a complete upstream handler... I wonder if it is a known use case?
The usual approach is to remove the Content-Length header if you
expect that the response length might be changed by your body
filter. You also have to either remove ETag or change it to a
weak one, if present. For examples see SSI filter, sub filter,
addition filter, and many others.
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