Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

3.21.6

Plugin version

No response

Node.js version

16.2

Operating system

Windows

Operating system version (i.e. 20.04, 11.3, 10)

10

Description

I am using fastify compress and it is working fine to compress a large string and returns to the client with no issues.
My problem is when the client sends content-encoding gzip and content-length of 462 with gzip'd payload, The uncompressed length is 1325 bytes.

authorization: 'Basic xxxxxxxxxxxxxxxxxxxxxx==',
'accept-encoding': 'br, deflate, gzip',
'content-type': 'text/plain',
'content-encoding': 'gzip',
'content-length': '462',
host: 'localhost:3000',
connection: 'close'

I appear to have 2 problems..
When the preparsing hook fires, I have looked in the payload and do not see anything that remotely looks like the 426 bytes of gzipped content. I don't appear to see it anywhere.

server.addHook("preParsing", (request, reply, payload, done) => {
  done(null, payload);
});

Where in the payload field is the inbound data expected to be found?

When the preparsing hook exits, fastify reports this:
Request body size did not match Content-Length
"name": "FastifyError",
"code": "FST_ERR_CTP_INVALID_CONTENT_LENGTH",
"statusCode": 400

If I switch my client to point at our current Tomcat server it works fine.

Steps to Reproduce

Not easy as there is a lot of code involved here with many external dependencies.

Expected Behavior

Would expect to have uncompressed data on exit from preParsing hook..