ssl: ERL-738 - Correct alert handling with new TLS sender process

With the new TLS sender process, solving ERL-622, TLS ALERTs sent in
the connection state must be encrypted and sent by the TLS sender
process. This to make sure that the correct encryption state is used
to encode the ALERTS. Care must also be taken to ensure a graceful
close down behavior both for normal shutdown and downgrading from TLS
to TCP.

The original TR ERL-738 is verified by cowboy tests, and close down
behavior by our tests. However we alas have not been able to yet
create a minimal test case for the originating problem.

Also it seems it has become less likely that we run in to the TCP
delivery problem, that is the guarantee is only on transport level,
not application level. Keep work around function in ssl_test_lib but
we can have better test as long as we do not get to much wobbling
tests.

1 files changed, 15 insertions, 2 deletions

diff --git a/lib/ssl/src/tls_sender.erl b/lib/ssl/src/tls_sender.erl
index db67d7ddff..ec03000b33 100644
--- a/lib/ssl/src/tls_sender.erl
+++ b/lib/ssl/src/tls_sender.erl
@@ -28,7 +28,8 @@
 -include("ssl_api.hrl").
 
 %% API
--export([start/0, start/1, initialize/2, send_data/2, send_alert/2, renegotiate/1,
+-export([start/0, start/1, initialize/2, send_data/2, send_alert/2,
+         send_and_ack_alert/2, renegotiate/1,
          update_connection_state/3, dist_tls_socket/1, dist_handshake_complete/3]).
 
 %% gen_statem callbacks
@@ -89,13 +90,21 @@ send_data(Pid, AppData) ->
 
 %%--------------------------------------------------------------------
 -spec send_alert(pid(), #alert{}) -> _. 
-%% Description: TLS connection process wants to end an Alert
+%% Description: TLS connection process wants to send an Alert
 %% in the connection state.
 %%--------------------------------------------------------------------
 send_alert(Pid, Alert) ->
     gen_statem:cast(Pid, Alert).
 
 %%--------------------------------------------------------------------
+-spec send_and_ack_alert(pid(), #alert{}) -> ok.
+%% Description: TLS connection process wants to send an Alert
+%% in the connection state and recive an ack.
+%%--------------------------------------------------------------------
+send_and_ack_alert(Pid, Alert) ->
+    gen_statem:cast(Pid, {ack_alert, Alert}).
+
+%%--------------------------------------------------------------------
 -spec renegotiate(pid()) -> {ok, WriteState::map()} | {error, closed}.
 %% Description: So TLS connection process can synchronize the 
 %% encryption state to be used when handshaking.
@@ -207,6 +216,10 @@ connection({call, From}, {dist_handshake_complete, _Node, DHandle}, #data{connec
     process_flag(priority, normal),
     Events = dist_data_events(DHandle, []),
     {next_state, ?FUNCTION_NAME, StateData#data{dist_handle = DHandle}, [{reply, From, ok} | Events]};
+connection(cast, {ack_alert, #alert{} = Alert}, #data{connection_pid = Pid} =StateData0) ->
+    StateData = send_tls_alert(Alert, StateData0),
+    Pid ! {self(), ack_alert},
+    {next_state, ?FUNCTION_NAME, StateData};
 connection(cast, #alert{} = Alert, StateData0) ->
     StateData = send_tls_alert(Alert, StateData0),
     {next_state, ?FUNCTION_NAME, StateData};