ssl: Add new sender process for TLS state machine

Separate sending and receiving when using TCP as transport
as prim_inet:send may block which in turn may result
in a deadlock between two Erlang processes communicating over
TLS, this is especially likely to happen when running Erlang distribution
over TLS.

1 files changed, 62 insertions, 5 deletions

diff --git a/lib/ssl/src/dtls_connection.erl b/lib/ssl/src/dtls_connection.erl
index bf3ff3a9a7..2a0b2b317d 100644
--- a/lib/ssl/src/dtls_connection.erl
+++ b/lib/ssl/src/dtls_connection.erl
@@ -36,7 +36,7 @@
 %% Internal application API
 
 %% Setup
--export([start_fsm/8, start_link/7, init/1]).
+-export([start_fsm/8, start_link/7, init/1, pids/1]).
 
 %% State transition handling	 
 -export([next_record/1, next_event/3, next_event/4,  handle_common_event/4]).
@@ -44,10 +44,10 @@
 %% Handshake handling
 -export([renegotiate/2, send_handshake/2, 
          queue_handshake/2, queue_change_cipher/2,
-         reinit_handshake_data/1, select_sni_extension/1, empty_connection_state/2]).
+         reinit/1, reinit_handshake_data/1, select_sni_extension/1, empty_connection_state/2]).
 
 %% Alert and close handling
--export([encode_alert/3,send_alert/2, close/5, protocol_name/0]).
+-export([encode_alert/3, send_alert/2, send_alert_in_connection/2, close/5, protocol_name/0]).
 
 %% Data handling
 -export([encode_data/3, passive_receive/2, next_record_if_active/1,
@@ -72,7 +72,7 @@ start_fsm(Role, Host, Port, Socket, {#ssl_options{erl_dist = false},_, Tracker}
     try 
 	{ok, Pid} = dtls_connection_sup:start_child([Role, Host, Port, Socket, 
 						     Opts, User, CbInfo]), 
-	{ok, SslSocket} = ssl_connection:socket_control(?MODULE, Socket, Pid, CbModule, Tracker),
+	{ok, SslSocket} = ssl_connection:socket_control(?MODULE, Socket, [Pid], CbModule, Tracker),
 	ssl_connection:handshake(SslSocket, Timeout)
     catch
 	error:{badmatch, {error, _} = Error} ->
@@ -100,6 +100,10 @@ init([Role, Host, Port, Socket, Options,  User, CbInfo]) ->
             EState = State0#state{protocol_specific = Map#{error => Error}},
 	    gen_statem:enter_loop(?MODULE, [], error, EState)
     end.
+
+pids(_) ->
+    [self()].
+    
 %%====================================================================
 %% State transition handling
 %%====================================================================	     
@@ -328,10 +332,14 @@ queue_change_cipher(ChangeCipher, #state{flight_buffer = Flight,
 	dtls_record:next_epoch(ConnectionStates0, write), 
     State#state{flight_buffer = Flight#{change_cipher_spec => ChangeCipher},
 		connection_states = ConnectionStates}.
+
+reinit(State) ->
+    %% To be API compatible with TLS NOOP here
+    reinit_handshake_data(State).
 reinit_handshake_data(#state{protocol_buffers = Buffers} = State) ->
     State#state{premaster_secret = undefined,
 		public_key_info = undefined,
-		tls_handshake_history = ssl_handshake:init_handshake_history(),
+                tls_handshake_history = ssl_handshake:init_handshake_history(),
                 flight_state = {retransmit, ?INITIAL_RETRANSMIT_TIMEOUT},
 		flight_buffer = new_flight(),
                 protocol_buffers =
@@ -365,6 +373,10 @@ send_alert(Alert, #state{negotiated_version = Version,
     send(Transport, Socket, BinMsg),
     State0#state{connection_states = ConnectionStates}.
 
+send_alert_in_connection(Alert, State) ->
+    _ = send_alert(Alert, State),
+    ok.
+
 close(downgrade, _,_,_,_) ->
     ok;
 %% Other
@@ -710,6 +722,12 @@ connection(internal, #client_hello{}, #state{role = server, allow_renegotiate =
     State1 = send_alert(Alert, State0),
     {Record, State} = ssl_connection:prepare_connection(State1, ?MODULE),
     next_event(?FUNCTION_NAME, Record, State);
+connection({call, From}, {application_data, Data}, State) ->
+    try
+        send_application_data(Data, From, ?FUNCTION_NAME, State)
+    catch throw:Error ->
+            ssl_connection:hibernate_after(?FUNCTION_NAME, State, [{reply, From, Error}])
+    end;
 connection(Type, Event, State) ->
      ssl_connection:?FUNCTION_NAME(Type, Event, State, ?MODULE).
 
@@ -1131,3 +1149,42 @@ log_ignore_alert(true, StateName, Alert, Role) ->
                         [Role, StateName, Txt]);
 log_ignore_alert(false, _, _,_) ->
     ok.
+
+send_application_data(Data, From, _StateName,
+                      #state{socket = Socket,
+                             negotiated_version = Version,
+                             protocol_cb = Connection,
+                             transport_cb = Transport,
+                             connection_states = ConnectionStates0,
+                             ssl_options = #ssl_options{renegotiate_at = RenegotiateAt}} = State0) ->
+       
+    case time_to_renegotiate(Data, ConnectionStates0, RenegotiateAt) of
+	true ->
+	    renegotiate(State0#state{renegotiation = {true, internal}}, 
+                        [{next_event, {call, From}, {application_data, Data}}]);
+	false ->
+	    {Msgs, ConnectionStates} =
+                Connection:encode_data(Data, Version, ConnectionStates0),
+            State = State0#state{connection_states = ConnectionStates},
+	    case Connection:send(Transport, Socket, Msgs) of
+                ok ->
+                    ssl_connection:hibernate_after(connection, State, [{reply, From, ok}]);
+                Result ->
+                    ssl_connection:hibernate_after(connection, State, [{reply, From, Result}])
+            end
+    end.
+
+time_to_renegotiate(_Data, 
+		    #{current_write := #{sequence_number := Num}}, 
+		    RenegotiateAt) ->
+    
+    %% We could do test:
+    %% is_time_to_renegotiate((erlang:byte_size(_Data) div
+    %% ?MAX_PLAIN_TEXT_LENGTH) + 1, RenegotiateAt), but we chose to
+    %% have a some what lower renegotiateAt and a much cheaper test
+    is_time_to_renegotiate(Num, RenegotiateAt).
+
+is_time_to_renegotiate(N, M) when N < M->
+    false;
+is_time_to_renegotiate(_,_) ->
+    true.