Remove R16 compatibility

Ranch is now made for and tested on 18+ only.

doc/src/guide/introduction.asciidoc

@@ -15,7 +15,7 @@ with socket programming and TCP protocols.
 
 Ranch is tested and supported on Linux, FreeBSD, OSX and Windows.
 
-Ranch is developed for Erlang/OTP R16B+.
+Ranch is developed for Erlang/OTP 18+.
 
 There are known issues with the SSL application found in Erlang/OTP
 18.3.2 and 18.3.3. These versions are therefore not supported.

doc/src/guide/listeners.asciidoc

@@ -169,14 +169,6 @@ from the connect function for the transport or the underlying socket library
 called on the passed in socket. You should connect the socket in
 `{active, false}` mode, as well.
 
-Note, however, that because of a bug in SSL, you cannot change ownership of an
-SSL listen socket prior to R16. Ranch will catch the error thrown, but the
-owner of the SSL socket will remain as whatever process created the socket.
-However, this will not affect accept behaviour unless the owner process dies,
-in which case the socket is closed. Therefore, to use this feature with SSL
-with an erlang release prior to R16, ensure that the SSL socket is opened in a
-persistant process.
-
 === Limiting the number of concurrent connections
 
 The `max_connections` transport option allows you to limit the number

src/ranch.erl

@@ -96,10 +96,7 @@ start_listener(Ref, Transport, TransOpts0, Protocol, ProtoOpts)
 					Children = supervisor:which_children(Pid),
 					{_, AcceptorsSup, _, _}
 						= lists:keyfind(ranch_acceptors_sup, 1, Children),
-					%%% Note: the catch is here because SSL crashes when you change
-					%%% the controlling process of a listen socket because of a bug.
-					%%% The bug will be fixed in R16.
-					catch Transport:controlling_process(Socket, AcceptorsSup);
+					Transport:controlling_process(Socket, AcceptorsSup);
 				_ ->
 					ok
 			end,