ssl: Implement DTLS state machine

Beta DTLS, not production ready. Only very basically tested, and
not everything in the SPEC is implemented and some things
are hard coded that should not be, so this implementation can not be consider
secure.

Refactor "TLS connection state" and socket handling, to facilitate
DTLS implementation.

Create dtls "listner" (multiplexor) process that spawns
DTLS connection process handlers.

Handle DTLS fragmentation.

Framework for handling retransmissions.

Replay Detection is not implemented yet.

Alerts currently always handled as in TLS.

lib/ssl/src/Makefile

@@ -50,6 +50,7 @@ MODULES= \
 	ssl_app \
 	ssl_dist_sup\
 	ssl_sup \
+	dtls_udp_sup \
 	inet_tls_dist \
 	inet6_tls_dist \
 	ssl_certificate\
@@ -71,7 +72,9 @@ MODULES= \
 	ssl_crl\
 	ssl_crl_cache \
 	ssl_crl_hash_dir \
-	ssl_socket \
+	tls_socket \
+	dtls_socket \
+	dtls_udp_listener\
 	ssl_listen_tracker_sup \
 	tls_record \
 	dtls_record \

lib/ssl/src/dtls_connection.hrl

@@ -29,20 +29,14 @@
 -include("ssl_connection.hrl").
 
 -record(protocol_buffers, {
-	  dtls_packets = [],              %%::[binary()],  % Not yet handled decode ssl/tls packets.
-          dtls_record_buffer = <<>>,      %%:: binary(),   % Buffer of incomplete records
-	  dtls_fragment_state,            %%:: [],         % DTLS fragments
-          dtls_handshake_buffer = <<>>,   %%:: binary(),   % Buffer of incomplete handshakes
-	  dtls_cipher_texts = [],         %%:: [binary()],
-	  dtls_cipher_texts_next          %%:: [binary()]  % Received for Epoch not yet active
+          dtls_record_buffer = <<>>,      %% Buffer of incomplete records
+	  dtls_handshake_next_seq = 0,
+	  dtls_flight_last,
+	  dtls_handshake_next_fragments = [], %% Fragments of the next handshake message
+	  dtls_handshake_later_fragments = [], %% Fragments of handsake messages come after the one in next buffer
+	  dtls_cipher_texts = []         %%:: [binary()],
 	 }).
 
--record(flight, {
-	  last_retransmit,
-	  last_read_seq,
-	  msl_timer,
-	  state,
-	  buffer        % buffer of not yet ACKed TLS records
-	 }).
+-define(INITIAL_RETRANSMIT_TIMEOUT, 1000). %1 sec
 
 -endif. % -ifdef(dtls_connection).

lib/ssl/src/dtls_connection_sup.erl

@@ -60,7 +60,7 @@ init(_O) ->
     StartFunc = {dtls_connection, start_link, []},
     Restart = temporary, % E.g. should not be restarted
     Shutdown = 4000,
-    Modules = [dtls_connection],
+    Modules = [dtls_connection, ssl_connection],
     Type = worker,
 
     ChildSpec = {Name, StartFunc, Restart, Shutdown, Type, Modules},

lib/ssl/src/dtls_handshake.hrl

@@ -46,12 +46,13 @@
 	  cookie
 	 }).
 
--record(dtls_hs_state,
-	{current_read_seq,
-	 starting_read_seq,
-	 highest_record_seq,
-	 fragments,
-	 completed
-	}).
+-record(handshake_fragment, {
+	  type,
+	  length,
+	  message_seq,               
+	  fragment_offset,           
+	  fragment_length,
+	  fragment
+	 }).
 
 -endif. % -ifdef(dtls_handshake).