Don't discard outgoing answers with Result-Code/E-bit errors

Outgoing answers missing a Result-Code AVP or setting an E-bit
inappropriately were discarded, but there's no particular reason for
doing so if the answer can be encoded, and the sender has no way of
knowing that their answer has been discarded. It's also inappropriate
that the message be discarded in the relay case. Answers are now sent,
and an error counter incremented.

2 files changed, 18 insertions, 9 deletions

diff --git a/lib/diameter/src/base/diameter_traffic.erl b/lib/diameter/src/base/diameter_traffic.erl
index 3b62afca47..e3ecd9c930 100644
--- a/lib/diameter/src/base/diameter_traffic.erl
+++ b/lib/diameter/src/base/diameter_traffic.erl
@@ -162,24 +162,28 @@ incr_error(Dir, Id, TPid) ->
 %% incr_rc/4
 %% ---------------------------------------------------------------------------
 
--spec incr_rc(send|recv, Pkt, TPid, Dict0)
+-spec incr_rc(send|recv, Pkt, TPid, DictT)
    -> {Counter, non_neg_integer()}
     | Reason
  when Pkt :: #diameter_packet{},
       TPid :: pid(),
-      Dict0 :: module(),
+      DictT :: module() | {module(), module(), module()},
       Counter :: {'Result-Code', integer()}
                | {'Experimental-Result', integer(), integer()},
       Reason :: atom().
 
-incr_rc(Dir, Pkt, TPid, Dict0) ->
+incr_rc(Dir, Pkt, TPid, {Dict, _, _} = DictT) ->
     try
-        incr_result(Dir, Pkt, TPid, {Dict0, Dict0, Dict0})
+        incr_result(Dir, Pkt, TPid, DictT)
     catch
         exit: {E,_} when E == no_result_code;
                          E == invalid_error_bit ->
+            incr(TPid, {msg_id(Pkt#diameter_packet.header, Dict), Dir, E}),
             E
-    end.
+    end;
+
+incr_rc(Dir, Pkt, TPid, Dict0) ->
+    incr_rc(Dir, Pkt, TPid, {Dict0, Dict0, Dict0}).
 
 %% ---------------------------------------------------------------------------
 %% pending/1
@@ -678,7 +682,7 @@ local(Msg, TPid, {Dict, AppDict, Dict0} = DictT, Fs, ReqPkt) ->
                  reset(make_answer_packet(Msg, ReqPkt), Dict, Dict0),
                  Fs),
     incr(send, Pkt, TPid, AppDict),
-    incr_result(send, Pkt, TPid, DictT),  %% count outgoing
+    incr_rc(send, Pkt, TPid, DictT),  %% count outgoing
     send(TPid, Pkt).
 
 %% reset/3
diff --git a/lib/diameter/test/diameter_traffic_SUITE.erl b/lib/diameter/test/diameter_traffic_SUITE.erl
index 4b67372016..92c81d2d18 100644
--- a/lib/diameter/test/diameter_traffic_SUITE.erl
+++ b/lib/diameter/test/diameter_traffic_SUITE.erl
@@ -414,12 +414,13 @@ send_eval(Config) ->
         = call(Config, Req).
 
 %% Send an accounting ACR that the server tries to answer with an
-%% inappropriate header, resulting in no answer being sent and the
-%% request timing out.
+%% inappropriate header. That the error is detected is coded in
+%% handle_answer.
 send_bad_answer(Config) ->
     Req = ['ACR', {'Accounting-Record-Type', ?EVENT_RECORD},
                   {'Accounting-Record-Number', 2}],
-    {timeout, _} = call(Config, Req).
+    ?answer_message(?SUCCESS)
+        = call(Config, Req).
 
 %% Send an ACR that the server callback answers explicitly with a
 %% protocol error.
@@ -1057,6 +1058,10 @@ answer(Pkt, Req, _Peer, Name, #group{client_dict0 = Dict0}) ->
     [R | Vs] = Dict:'#get-'(answer(Ans, Es, Name)),
     [Dict:rec2msg(R) | Vs].
 
+answer(Rec, Es, send_bad_answer) ->
+    [{5004, #diameter_avp{name = 'Result-Code'}} | _] = Es,
+    Rec;
+
 answer(Rec, [_|_], N)
   when N == send_long_avp_length;
        N == send_short_avp_length;