Rewrite S2S incoming connections as a gen_statem

big_tests/tests/s2s_SUITE.erl

@@ -272,10 +272,10 @@ dialback_with_wrong_key(_Config) ->
     {ok, _} = rpc(rpc_spec(mim), ejabberd_s2s_out, start, [FromTo, StartType]),
     receive
         %% Remote server (fed1) rejected out request
-        {'$gen_event', {validity_from_s2s_out, false, FromTo}} ->
+        {'$gen_cast', {validity_from_s2s_out, false, FromTo}} ->
             ok
-        after 5000 ->
-            ct:fail(timeout)
+    after 5000 ->
+              ct:fail(timeout)
     end.
 
 nonascii_addr(Config) ->
@@ -512,6 +512,7 @@ element_count(in, false) ->
     % Since S2S connections are unidirectional, mim1 acts both as initiating,
     % and receiving (and authoritative) server in the dialback procedure.
     %   1. Stream start response from fed1 (as initiating server)
+    %     1.b. Stream features after the response
     %   2. Stream start from fed1 (as receiving server)
     %   3. Dialback key (step 1, as receiving server)
     %   4. Dialback verification request (step 2, as authoritative server)
@@ -520,13 +521,14 @@ element_count(in, false) ->
     % This process sends a new stream header, as it opens a new connection to fed1,
     % now acting as an authoritative server. Also see comment on L360 in ejabberd_s2s.
     %   6. Stream start response from fed1
+    %     6.b. Stream features after the response
     %   7. Dialback verification response (step 3, as receiving server)
     %   8. Message from federated Alice
     % The number can be seen as the sum of all arrows from the dialback diagram, since mim
     % acts as all three roles in the two dialback procedures that occur:
     % https://xmpp.org/extensions/xep-0220.html#intro-howitworks
     % (6 arrows) + one for stream header response + one for the actual message
-    8;
+    10;
 element_count(out, false) ->
     % Since S2S connections are unidirectional, mim1 acts both as initiating,
     % and receiving (and authoritative) server in the dialback procedure.
@@ -539,8 +541,9 @@ element_count(out, false) ->
     % sent as XML elements, but straight as text, and so these three events do not appear:
     %  - open stream to fed1,
     %  - stream response for fed1->mim stream,
+    %     -.b. Stream features after the response
     %  - open stream to fed1 as authoritative server.
-    5.
+    9.
 
 group_with_tls(both_tls_optional) -> true;
 group_with_tls(both_tls_required) -> true;

doc/developers-guide/accumulators.md

@@ -1,6 +1,6 @@
 # Accumulators
 
-XMPP stanza processing starts in the `mongoose_c2s` module, which receives the stanza from a socket, or in `ejabberd_s2s_in` which receives stanzas from federated XMPP clusters.
+XMPP stanza processing starts in the `mongoose_c2s` module, which receives the stanza from a socket, or in `mongoose_s2s_in` which receives stanzas from federated XMPP clusters.
 The stanza is processed and eventually it and/or other messages are sent out, either to the original sender, to another c2s process within the same MongooseIM installation, or to another XMPP server.
 
 At the beginning of the main processing chain an accumulator is created containing following set of keys:

include/mongoose_ns.hrl

@@ -2,6 +2,8 @@
 -define(MONGOOSEIM_NS_HRL, true).
 
 -define(NS_CLIENT,              <<"jabber:client">>).
+-define(NS_SERVER,              <<"jabber:server">>).
+-define(NS_SERVER_DIALBACK,     <<"jabber:server:dialback">>).
 -define(NS_COMPONENT_ACCEPT,    <<"jabber:component:accept">>).
 -define(NS_CONFERENCE,          <<"jabber:x:conference">>).
 -define(NS_DISCO_ITEMS,         <<"http://jabber.org/protocol/disco#items">>).

src/config/mongoose_config_spec.erl

@@ -274,14 +274,17 @@ xmpp_listener_common() ->
                        <<"proxy_protocol">> => #option{type = boolean},
                        <<"reuse_port">> => #option{type = boolean},
                        <<"shaper">> => #option{type = atom,
-                                               validate = non_empty}},
+                                               validate = non_empty},
+                       <<"state_timeout">> => #option{type = int_or_infinity,
+                                                      validate = non_negative}},
              defaults = #{<<"backlog">> => 1024,
                           <<"max_connections">> => infinity,
                           <<"max_stanza_size">> => 0,
                           <<"num_acceptors">> => 100,
                           <<"proxy_protocol">> => false,
                           <<"reuse_port">> => false,
-                          <<"shaper">> => none}}.
+                          <<"shaper">> => none,
+                          <<"state_timeout">> => 5000}}.
 
 xmpp_listener_extra(<<"c2s">>) ->
     #section{items = #{<<"access">> => #option{type = atom,
@@ -291,12 +294,10 @@ xmpp_listener_extra(<<"c2s">>) ->
                                                  validate = {module, ejabberd_auth}},
                                  validate = unique},
                        <<"backwards_compatible_session">> => #option{type = boolean},
-                       <<"state_timeout">> => #option{type = int_or_infinity,
-                                                      validate = non_negative},
                        <<"tls">> => tls([server, xmpp])},
              defaults = #{<<"access">> => all,
-                          <<"backwards_compatible_session">> => true,
-                          <<"state_timeout">> => 5000}};
+                          <<"backwards_compatible_session">> => true
+                         }};
 xmpp_listener_extra(<<"component">>) ->
     #section{items = #{<<"access">> => #option{type = atom,
                                                validate = non_empty},
@@ -306,15 +307,12 @@ xmpp_listener_extra(<<"component">>) ->
                        <<"hidden_components">> => #option{type = boolean},
                        <<"password">> => #option{type = string,
                                                  validate = non_empty},
-                       <<"state_timeout">> => #option{type = int_or_infinity,
-                                                      validate = non_negative},
                        <<"tls">> => tls([server, xmpp_tls])},
              required = [<<"password">>],
              defaults = #{<<"access">> => all,
                           <<"check_from">> => true,
                           <<"conflict_behaviour">> => disconnect,
-                          <<"hidden_components">> => false,
-                          <<"state_timeout">> => 5000}};
+                          <<"hidden_components">> => false}};
 xmpp_listener_extra(<<"s2s">>) ->
     #section{items = #{<<"tls">> => tls([server, xmpp])}}.