Re: [Bug-wget] [Bug-Wget] Wget closes connection despite Keep-Alive

[Tim Rühsen]

Am Dienstag, 4. November 2014, 23:25:40 schrieb Darshit Shah:
> While looking at some debug output from Wget, I noticed that in case of a
> 416 Range Not Satisfiable response, Wget forces the connection close
> despite the fact that the server explicitly sent a `Connection: Keep-Alive`
> header.
> 
> Looking at the code, I found this at http.c:2775
> 
> 
>       CLOSE_INVALIDATE (sock);        /* would be CLOSE_FINISH, but there
>                                    might be more bytes in the body. */
> 
> I'm not sure what exactly we're trying to protect in this case. Why is
> CLOSE_INVALIDATE required instead of CLOSE_FINISH? If the server responds
> with a 416 status, there should be no more data in the stream and we should
> be able to reuse that connection without any issues.
> 
> What am I missing here?

The code is with an if construct with || :
if (statcode == HTTP_STATUS_RANGE_NOT_SATISFIABLE
      || (!opt.timestamping && hs->restval > 0 && statcode == HTTP_STATUS_OK
          && contrange == 0 && contlen >= 0 && hs->restval >= contlen))
    {

So if statcode == HTTP_STATUS_RANGE_NOT_SATISFIABLE i guess we could use 
CLOSE_FINISH. But I can't judge that for the other part of the expression.
If in doubt, CLOSE_INVALIDATE might be a better choice than CLOSE_FINISH.
Wget simply opens a new connection for the next request in this case.


> I wanted to write a test case to demonstrate this, but detecting a closed
> socket will take more than a quick test case. I'll sit down and write the
> required functionality to generate the relevant test case when I can.

Don't spend too much time here. It is not a bug, more of a missing feature. 
And also a very seldom used one. And how I read the comment, servers might 
behave buggy. And again, in that case it seems more reliable when Wget closes 
the connection and opens a new one.


Tim

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