Prevent the same delivery tag being used more than once.

Note that we change from command_invalid to not_found as the former is a
connection error, and the latter a channel error. Both 0-8 and 0-9-1 specify
a channel error.

1 files changed, 2 insertions, 6 deletions

diff --git a/src/rabbit_channel.erl b/src/rabbit_channel.erl
index f355bef314..035ce89e4b 100644
--- a/src/rabbit_channel.erl
+++ b/src/rabbit_channel.erl
@@ -465,11 +465,6 @@ handle_method(#'basic.ack'{delivery_tag = DeliveryTag,
               _, State = #ch{transaction_id = TxnKey,
                              next_tag = NextDeliveryTag,
                              unacked_message_q = UAMQ}) ->
-    if DeliveryTag >= NextDeliveryTag ->
-            rabbit_misc:protocol_error(
-              command_invalid, "unknown delivery tag ~w", [DeliveryTag]);
-       true -> ok
-    end,
     {Acked, Remaining} = collect_acks(UAMQ, DeliveryTag, Multiple),
     Participants = ack(TxnKey, Acked),
     {noreply, case TxnKey of
@@ -968,7 +963,8 @@ collect_acks(ToAcc, PrefixAcc, Q, DeliveryTag, Multiple) ->
                                  QTail, DeliveryTag, Multiple)
             end;
         {empty, _} ->
-            {ToAcc, PrefixAcc}
+            rabbit_misc:protocol_error(
+              not_found, "unknown delivery tag ~w", [DeliveryTag])
     end.
 
 add_tx_participants(MoreP, State = #ch{tx_participants = Participants}) ->