GSOC2017PatchRequirement

As part of their Google Summer of Code 2017 applications to ns-3, we require that students produce a patch for ns-3. This will allow us to gauge your ability to dive into source code, understand it, make a modification, and proceed to build and verify if your modification works.

A patch in this regard can be at least one of the following:

• If you already have contributed a patch for ns-3 in the past, point us to the relevant commits in our code repository or the bug tracker issue, and your patch requirement is satisfied.
• If not the above, either complete the minimum requirement test given below, or pick a bug in our Bugzilla that does not already have a patch pending, and try to fix it.

Minimum requirement patch

Setting up the environment

Perform the following steps (you may want to review our Installation page):

• Download the ns-3.26 release, or clone it from Mercurial:

 $: hg clone http://code.nsnam.org/ns-3.26

or

 $: wget http://www.nsnam.org/release/ns-allinone-3.26.tar.bz2

• Verify if you can build ns-3 and run the program to be patched

 $: ./waf configure --disable-python --enable-examples
 $: ./waf build
 $: ./waf --run tcp-bulk-send

Objective

The example program 'examples/tcp/tcp-bulk-send.cc' should be modified to output the evolution of the TCP congestion window, in the direction of the file transfer (node 0 to 1), in an unevenly spaced time-series format. Currently, the example will print out:

 $: ./waf --run tcp-bulk-send
 Total Bytes Received: 564248

Your patch to this program alone (i.e. do not change ns-3.26 TCP code in any way) should output something like this:

 $: ./waf --run tcp-bulk-send
 0.011856s 536
 0.033024s 1072
 0.062768s 1608
 0.092512s 2144
 (...)
 9.98802s 286760
 Total Bytes Received: 564248

Hint 1: Tracing of the TCP 'CongestionWindow' trace source can be used, either by obtaining a pointer to the socket being used by the BulkSendApplication, or by using a config path to connect to the trace source. For tutorial on tracing, see:

• Slides
• Video

Hint 2: The ns-3 tutorial section on tracing is relevant to this problem.

What to submit

• A patch to tcp-bulk-send.cc that accomplishes the objectives. In your application, point us to a publicly available URL where you've hosted the patch (like a "gist" on github.com for instance). See also some guidelines here about formatting patches for review. If you need help with this step, contact the ns-3 Org Admin (Tom Henderson) for advice.

Note: Keep your solution private by pasting the link in your application to Google, not posting it on the mailing list.