simplify http-server example

[kortschak]

I was working on an HTTP endpoint that requires a POST body, but found it difficult to understand how to hold the httpx package in a way that allowed me to obtain the body contents as the request type does not expose the content length and does not allow a read to io.EOF of the net conn.

If I attempt to read the contents of buf to completion after the headers have been read, I get a "curl: (52) Empty reply from server" from the test client and see level=ERROR msg=Stack.RecvEth err="dropped packet" and poll error: dropped packet in the server logs.

This appears to be due to the request waiting on the response because the buffer believes the conn still has data; I see this: level=ERROR msg="read body" err="i/o timeout". It seems I need to know the content length to be able to know when to stop.

To get around this I tried using the standard library's net/http package in the servers code and it works. This change is the equivalent change for the http-server example.

Note that while it works (and in the server that I am writing that prompted this does not cause any poll error: dropped packet error to be emitted, I do see that happening in the server example. I have been unable to see how the two programs differ in a way that would explain this. The error is coming from (*TCPListener).recv.

[soypat]

I'd like to add this as a separate example. I'd expect the net/http library to be heavy on allocations as expected from a stdlib package. maybe rename example to http-server-stdlib

[kortschak]

That seems reasonable. It would be good then to expand the httpx API to allow safe collection of request bodies.