Implement Active TCP-ICE

[dgunay]

Description

Implementing Active TCP ICE to enable Pion to connect to passive TCP ICE hosts.

Still relatively new to WebRTC and ICE, so if I stray from RFC 6544 or otherwise misunderstand something fundamental about the way this should work please don't hesitate to let me know.

Reference issue

#245 - Continued ICE improvements

[dgunay]

@Sean-Der dove into the code a bit and tried to open a TCP connection to the remote. That eventually lead me into the gatherCandidatesLocal function. I have a question (maybe I should just read the RFC front to back):

I see the code structure right now assumes each local candidate opens a PacketConn on some port; section 4.1 of RFC6544:

First, agents SHOULD obtain host candidates as described in
Section 5.1. Then, each agent SHOULD "obtain" (allocate a
placeholder for) an active host candidate for each component of each
TCP-capable media stream on each interface that the host has. The
agent does not yet have to actually allocate a port for these
candidates, but they are used for the creation of the check lists.

candidateBase.start() kicks off recvLoop(), which crashes because I didn't provide a port. Any suggestions on how we can best structure the code to support placeholder active TCP candidates?

I also tend to litter my code with TODOs and FIXMEs so I might have tugged on some threads there that I'm forgetting.

[codecov]

Codecov Report

Merging #392 (238317f) into master (6d30128) will decrease coverage by 53.10%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##           master     #392       +/-   ##
===========================================
- Coverage   78.48%   25.38%   -53.11%     
===========================================
  Files          33       33               
  Lines        2598     2616       +18     
===========================================
- Hits         2039      664     -1375     
- Misses        391     1924     +1533     
+ Partials      168       28      -140     

Flag	Coverage Δ
go	?
wasm	25.38% <0.00%> (-0.18%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
agent.go	0.00% <0.00%> (-81.72%)	⬇️
agent_config.go	0.00% <ø> (-84.38%)	⬇️
candidate_base.go	55.17% <ø> (-27.59%)	⬇️
gather.go	0.00% <0.00%> (-67.68%)	⬇️
candidate_peer_reflexive.go	0.00% <0.00%> (-84.62%)	⬇️
transport.go	0.00% <0.00%> (-82.70%)	⬇️
agent_stats.go	0.00% <0.00%> (-79.63%)	⬇️
udp_mux.go	0.00% <0.00%> (-77.87%)	⬇️
... and 15 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6d30128...238317f. Read the comment docs.

[Sean-Der]

@dgunay added you to the Pion org so you can push branches/run CI.

I would override recvLoop maybe? Like CandidateRelay does with close. Reading PR now.

[Sean-Der]

What you will actually want I believe is one CandidateHost that contains a TCP Socket.

When AddICECandidate comes in with a passive candidate you send off a connection request.

You will need a recvLoop per connection attempt. So I think overriding it completely makes sense!

[ashellunts]

Hi @dgunay, if you need helping hands with this, let me know.

I was also planning to work on active tcp, but you already made good progress.

[dgunay]

Hi @dgunay, if you need helping hands with this, let me know.

I was also planning to work on active tcp, but you already made good progress.

Sure! I will not be super active until I finish my masters in December, so if you'd like to take this and build on it feel free.

[ashellunts]

Great, I will.

[dgunay]

Voluntarily closing this in favor of #394 - hopefully someone else with the desire or the need will help get it across the finish line.