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Date: Mon, 29 Aug 2022 06:42:45 +0000
From: Eric Wong <e@yhbt.net>
To: Samuel Williams <samuel@oriontransfer.net>
Cc: unicorn-public@yhbt.net
Subject: Re: Is Rack partial hijack supported?
Message-ID: <20220829064245.GA1272@dcvr>
References: <B9DAECE5-D139-44E5-A442-9FAF3E2A920B@oriontransfer.net>
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Samuel Williams <samuel@oriontransfer.net> wrote:
> Hi Eric,
> 
> I’ve been testing Rack server conformance and behaviour and noticed that while unicorn advertises `env[‘rack.hijack?’]` as true, it fails to correctly stream the following response:
> 
> if env['rack.hijack?']
>   callback = proc do |stream|
>     stream.write "Hello World"
>     stream.close
>   end
>   
>   return [200, {'rack.hijack' => callback}, nil]
> else
>   [404, {}, []]
> end

That looks fine...

> Am I misunderstanding something about how this should work or does Unicorn not support partial hijack?

I wonder if it's Rack::Chunked being loaded by default w/
RACK_ENV=(development|deployment) being the problem.

What error do you see? (assuming you're using curl or similar
for testing).

Does using `-E none' or RACK_ENV=none fix it?

$ cat >hijack.ru <<EOF
use Rack::ContentType, 'text/plain'
run(lambda do |env|
  if env['rack.hijack?']
    callback = proc do |stream|
      stream.write "Hello World"
      stream.close
    end
    return [200, {'rack.hijack' => callback}, nil]
  else
    [404, {}, []]
  end
end)
EOF

# This works fine:
$ unicorn -E none hijack.ru
$ curl -Ssf http://0:8080/

# This fails since Rack::Chunk is loaded by default:
$ unicorn hijack.ru
$ curl -Ssf http://0:8080/
curl: (56) Illegal or missing hexadecimal sequence in chunked-encoding

So I think the hijack callback needs to do the chunking itself;
I'm not sure...

That said, I have no idea if rack.hijack gets used at all w/
unicorn; and I seem to recall there being a bit of confusion
on how hijack and middleware would interact...


(please reply-all for archival purposes, thanks)