[Development] DTLS support in Qt

[Thiago Macieira]

Hello

Last year at QCS, I joined the Networking discussions and one of my requests 
was DTLS support. Everything else needed to support IoT was already in place, 
in flight (the QNetworkDatagram class) or I could do it myself (new API for 
QNetworkInterface coming soon).

DTLS was the only thing I wasn't allowed to contribute and no one else has 
stepped up in the last year.

So I decided to implement it myself. I've now got a proof of concept to 
support DTLS over QUdpSocket and it already manages to connect one client and 
server, verify the certificate (haven't tested failure) and communicate with 
itself, with the "openssl" binary and with "gnutls-serv" binary. I've got 
approval from Intel to contribute it.

I'd like Qt to have DTLS support. Should *I* contribute it? This question is 
important because there used to be restrictions on "US persons" contributing 
cryptography-related code. I need an answer from the Qt Project.

If NO:
Then who will write it? When? Can you finish it by Qt 5.11 feature freeze?

If YES:
Then what module should it be in?
 a) QtNetwork
	Would be ideal, as there are quite a few changes to QSslSocketBackend, 
	QSslContext, etc. that are required. We'd also reuse the dynamic OpenSSL 
	loading. If I can implement DTLS support in QtNetwork, I can make these 
	changes myself.
 b) another module, outside of qtbase
	This module would be licenced LGPLv3, no commercial.
	Not ideal, but workable. The changes I mentioned above would still need to 
	be implemented, so we'd need a volunteer to implement them and work with 	
	me. It shouldn't be too difficult.
 c) not in Qt
	Really not ideal. Would make for a crappy API and would increase the 
	development time at least threefold, probably more.

I'll be really disappointed if the answer is "no, we won't accept this 
contribution and we won't develop it for 5.11 either".

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center