Discard incoming requests after outgoing DPR

Since there's a race between an answer being sent and the connection
being closed upon the reception of DPA that's likely to be lost, and
because of the questionability of sending messages after DPR, as
discussed in the parent commit. An exception is made for DPR so that
simultaneous DPR in both directions doesn't result in it being discarded
on both ends.

1 files changed, 18 insertions, 5 deletions

diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl
index e733e973ab..23bba701eb 100644
--- a/lib/diameter/src/base/diameter_peer_fsm.erl
+++ b/lib/diameter/src/base/diameter_peer_fsm.erl
@@ -516,12 +516,9 @@ encode(Rec, Dict) ->
 
 recv(#diameter_packet{header = #diameter_header{} = Hdr}
      = Pkt,
-     #state{parent = Pid,
-            dictionary = Dict0}
+     #state{dictionary = Dict0}
      = S) ->
-    Name = diameter_codec:msg_name(Dict0, Hdr),
-    Pid ! {recv, self(), Name, Pkt},
-    rcv(Name, Pkt, S);
+    recv1(diameter_codec:msg_name(Dict0, Hdr), Pkt, S);
 
 recv(#diameter_packet{header = undefined,
                       bin = Bin}
@@ -532,6 +529,22 @@ recv(#diameter_packet{header = undefined,
 recv(Bin, S) ->
     recv(#diameter_packet{bin = Bin}, S).
 
+%% recv1/3
+
+%% Incoming request after DPR has been sent: discard. Don't discard
+%% DPR, so both ends don't do so when sending simultaneously.
+recv1(Name,
+      #diameter_packet{header = #diameter_header{is_request = true} = H},
+      #state{dpr = {_,_}})
+  when Name /= 'DPR' ->
+    invalid(false, recv_after_dpr, H);
+
+%% Any other message with a header and no length errors: send to the
+%% parent.
+recv1(Name, Pkt, #state{parent = Pid} = S) ->
+    Pid ! {recv, self(), Name, Pkt},
+    rcv(Name, Pkt, S).
+
 %% recv/3
 
 recv(#diameter_header{length = Len}