Re: [Bug-wget] GSoC15: Speed up Wget's Download Mechanism

[Tim Ruehsen]

Hi Hubert,

congrats for being selected for GSOC !

Here is a researchers report about testing TFO.
https://reproducingnetworkresearch.wordpress.com/2014/06/03/cs244-14-tcp-fast-open-2/

Some additional thoughts:
- TFO won't work with HTTPS as long as the used SSL library does not support 
TFO.
- Servers might not be ready to detect network-doubled SYN packets. No problem 
with GET (well, there might be corner cases or misconfigurations), but might 
be a general problem with POST.
- I am not aware how to (programmatically) detect TFO on the (test) server 
side. Maybe there is a way via /proc file system. Maybe a question for the 
kernel mailing list !?
- I recently made a patch for torify/torsocks to catch sendto(). It was 
accepted, but I am not sure if they made a new release already. At least on 
not-up-to-date systems, TFO would leak (circumvent tor network). We should 
keep this in mind for documentation.
- Because of these point, TFO should not be enabled by default.

TFO is an interesting technology. RTT is an issue that becomes more relevant 
with faster servers and faster networks. Even with the speed of light, you 
have a RTT of ~130ms from one side of the world to the other. 20.000km back 
and forth. TFO is part of the answer :-)

Have fun !

Tim

On Wednesday 29 April 2015 10:02:48 Hubert Tarasiuk wrote:
> Hello developers,
> 
> My proposal for *Speed up Wget's Download Mechanism* has been accepted
> by the mentors!
> 
> There are two tasks to be done there:
> - conditional GET requests (if-modified-since) (RFC7232)
> - TCP Fast Open (RFC7413)
> 
> A summarized version of my proposal is available:
> http://pliki.h.trsk.org/gsoc/wget_public.pdf
> 
> IMHO it is quite obvious how the first feature should be implemented in
> Wget. However, there is some more moving around needed to use TFO. I
> have proposed two possible ways in the above PDF. Perhaps you can
> express your opinion about the approaches, or you have another idea for
> accomplishing it?
> 
> Another issue I am thinking about is how to test the TFO feature. I am
> not very familiar with network API in Python, but my first idea would be
> to count the TCP segments sent and received and/or to check that the
> first packet (with SYN flag) contains data (the request). What do you think?
> 
> I will be thankful for any other suggestions, as well.
> 
> Have a good day,
> Hubert

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