Add check for ALPN

[ericrange]

Feel free to use it:

#! /usr/bin/env python3
import socket
import ssl

HOST = 'secure.deutschebank.be'
PORT = 443
PROTOCOLS = ['h2', 'spdy/3', 'http/1.1']

def supports_alpn():
	try:
		ctx = ssl.create_default_context()
		ctx.check_hostname = False
		ctx.verify_mode = ssl.CERT_NONE
		ctx.set_alpn_protocols(PROTOCOLS)

		connection = ctx.wrap_socket(
		   socket.socket(socket.AF_INET, socket.SOCK_STREAM), server_hostname=HOST)

		connection.connect((HOST, PORT))

		return connection.selected_alpn_protocol() != None

		#TODO : Connection close

	except:
		pass

	return False


def supports_npn():
	try:
		ctx = ssl.create_default_context()
		ctx.check_hostname = False
		ctx.verify_mode = ssl.CERT_NONE
		ctx.set_npn_protocols(PROTOCOLS)

		connection = ctx.wrap_socket(
		   socket.socket(socket.AF_INET, socket.SOCK_STREAM), server_hostname=HOST)

		connection.connect((HOST, PORT))

		return connection.selected_npn_protocol() != None

		#TODO : Connection close

	except:
		pass

	return False

[nabla-c0d3]

Since Python 3.6 is now the minimum version, this should be easy to add (ALPN support is only available since Python 3.5). Also, only ALPN should be needed as it deprecates NPN (https://www.imperialviolet.org/2013/03/20/alpn.html).

[mynameiswillporter]

Bumping this to indicate support for an ALPN check. The ALPN check is important to be able to evaluate susceptibility and the ability to mitigate ALPACA type attacks.