add PSDBU part or the EPFAR feature

Support `PFCP Session Deleted By the UP function` procedure that is part
of the EPFAR (Enhanced PFCP Association Release) feature.
The actually release procedure is not supported, but the "Deleted By the UPF"
can already be used to signal session deletion in the UPF

apps/ergw_core/src/ergw_gtp_gsn_lib.erl

@@ -11,7 +11,7 @@
 	  {parse_transform, cut}]).
 
 -export([connect_upf_candidates/4, create_session/10]).
--export([triggered_charging_event/4, usage_report/3, close_context/3]).
+-export([triggered_charging_event/4, usage_report/3, close_context/3, close_context/4]).
 -export([update_tunnel_endpoint/3, handle_peer_change/3, update_tunnel_endpoint/2,
 	 apply_bearer_change/5]).
 
@@ -232,15 +232,20 @@ usage_report(URRActions, UsageReport, #{pfcp := PCtx, 'Session' := Session}) ->
 %% close_context/3
 close_context(_, {API, TermCause}, Context) ->
     close_context(API, TermCause, Context);
-close_context(API, TermCause, #{pfcp := PCtx, 'Session' := Session} = Data)
+close_context(API, TermCause, #{pfcp := PCtx} = Data)
   when is_atom(TermCause) ->
     UsageReport = ergw_pfcp_context:delete_session(TermCause, PCtx),
-    ergw_gtp_gsn_session:close_context(TermCause, UsageReport, PCtx, Session),
-    ergw_prometheus:termination_cause(API, TermCause),
-    maps:remove(pfcp, Data);
+    close_context(API, TermCause, UsageReport, Data);
 close_context(_API, _TermCause, Data) ->
     Data.
 
+%% close_context/4
+close_context(API, TermCause, UsageReport, #{pfcp := PCtx, 'Session' := Session} = Data)
+  when is_atom(TermCause) ->
+    ergw_gtp_gsn_session:close_context(TermCause, UsageReport, PCtx, Session),
+    ergw_prometheus:termination_cause(API, TermCause),
+    maps:remove(pfcp, Data).
+
 %%====================================================================
 %% Helper
 %%====================================================================

apps/ergw_core/src/gtp_context.erl

@@ -387,6 +387,23 @@ handle_event({call, From},
 	    {next_state, shutdown, Data, [{reply, From, {ok, PCtx}}]}
     end;
 
+%% PFCP Session Deleted By the UP function
+handle_event({call, From},
+	     {sx, #pfcp{type = session_report_request,
+			ie = #{pfcpsrreq_flags := #pfcpsrreq_flags{psdbu = 1},
+			       report_type := ReportType} = IEs}},
+	     _State, #{pfcp := PCtx} = Data0) ->
+    TermCause =
+	case ReportType of
+	    #report_type{upir = 1} ->
+		up_inactivity_timeout;
+	    _ ->
+		deleted_by_upf
+	end,
+    UsageReport = maps:get(usage_report_srr, IEs, undefined),
+    Data = ergw_gtp_gsn_lib:close_context('pfcp', TermCause, UsageReport, Data0),
+    {next_state, shutdown, Data, [{reply, From, {ok, PCtx}}]};
+
 %% User Plane Inactivity Timer expired
 handle_event({call, From},
 	     {sx, #pfcp{type = session_report_request,

apps/ergw_core/test/ergw_test_sx_up.erl

@@ -6,7 +6,7 @@
 
 %% API
 -export([start/2, stop/1, restart/1,
-	 send/2, send/3, usage_report/4,
+	 send/2, send/3, usage_report/4, usage_report/5,
 	 up_inactivity_timer_expiry/2,
 	 up_quota_validity_time_expiry/2,
 	 reset/1, history/1, history/2,
@@ -73,7 +73,10 @@ send(Role, SEID, Msg) ->
     gen_server:call(server_name(Role), {send, SEID, Msg}).
 
 usage_report(Role, PCtx, MatchSpec, Report) ->
-    gen_server:call(server_name(Role), {usage_report, PCtx, MatchSpec, Report}).
+    usage_report(Role, PCtx, MatchSpec, [], Report).
+
+usage_report(Role, PCtx, MatchSpec, IEs, Report) ->
+    gen_server:call(server_name(Role), {usage_report, PCtx, MatchSpec, IEs, Report}).
 
 up_inactivity_timer_expiry(Role, PCtx) ->
     gen_server:call(server_name(Role), {up_inactivity_timer_expiry, PCtx}).
@@ -215,15 +218,15 @@ handle_call({send, Msg}, _From,
     {reply, ok, State};
 
 handle_call({usage_report, #pfcp_ctx{seid = #seid{cp = SEID}, urr_by_id = Rules},
-	     MatchSpec, Report}, _From, State0) ->
+	     MatchSpec, IEs0, Report}, _From, State0) ->
     Ids = ets:match_spec_run(maps:to_list(Rules), ets:match_spec_compile(MatchSpec)),
     URRs =
 	if is_function(Report, 2) ->
 		lists:foldl(Report, [], Ids);
 	   true ->
 		[#usage_report_srr{group = [#urr_id{id = Id}|Report]} || Id <- Ids]
 	end,
-    IEs = [#report_type{usar = 1}|URRs],
+    IEs = IEs0 ++ [#report_type{usar = 1}|URRs],
     SRreq = #pfcp{version = v1, type = session_report_request, ie = IEs},
     State = do_send(SEID, SRreq, State0),
     {reply, ok, State};

apps/ergw_core/test/pgw_SUITE.erl

@@ -697,6 +697,7 @@ common() ->
      sx_upf_restart,
      sx_timeout,
      sx_ondemand,
+     pfcp_session_deleted_by_the_up_function,
      gy_validity_timer_cp,
      gy_validity_timer_up,
      simple_aaa,
@@ -2941,6 +2942,45 @@ sx_ondemand(Config) ->
     ok = meck:wait(?HUT, terminate, '_', ?TIMEOUT),
     wait4contexts(?TIMEOUT).
 
+%%--------------------------------------------------------------------
+pfcp_session_deleted_by_the_up_function() ->
+    [{doc, "Test TEBUR with PSDBU (Ts 29.244, clause 5.18"}].
+pfcp_session_deleted_by_the_up_function(Config) ->
+    CtxKey = #context_key{socket = 'irx-socket', id = {imsi, ?'IMSI', 5}},
+
+    {GtpC, _, _} = create_session(Config),
+
+    {_Handler, Server} = gtp_context_reg:lookup(CtxKey),
+    true = is_pid(Server),
+    {ok, PCtx} = gtp_context:test_cmd(Server, pfcp_ctx),
+
+    MatchSpec = ets:fun2ms(fun({Id, _}) -> Id end),
+    IEs = [#pfcpsrreq_flags{psdbu = 1}],
+    Report =
+	[#usage_report_trigger{tebur = 1, _= 0},
+	 #volume_measurement{total = 5, uplink = 2, downlink = 3},
+	 #tp_packet_measurement{total = 12, uplink = 5, downlink = 7}],
+
+    lists:foreach(
+      fun(_X) ->
+	      ct:sleep(100),
+	      ergw_test_sx_up:usage_report('pgw-u01', PCtx, MatchSpec, IEs, Report)
+      end, lists:seq(1, 3)),
+
+    ct:sleep(100),
+    delete_session(not_found, GtpC),
+
+    ?equal(true, meck:called(ergw_aaa_session, invoke, ['_', '_', {gx, 'CCR-Terminate'}, '_'])),
+    ?equal(true, meck:called(ergw_aaa_session, invoke, ['_', '_', {gy, 'CCR-Terminate'}, '_'])),
+    ?equal(true, meck:called(ergw_aaa_session, invoke, ['_', '_', stop, '_'])),
+
+    ?equal([], outstanding_requests()),
+    ok = meck:wait(?HUT, terminate, '_', ?TIMEOUT),
+    wait4contexts(?TIMEOUT),
+
+    meck_validate(Config),
+    ok.
+
 %%--------------------------------------------------------------------
 
 gy_validity_timer_cp() ->