Add transport_opt() length_errors

The value determines whether or not an unexpected message length in the
header of an incoming messages causes the peer process to exit, the
message to be discarded or handled as usual. The latter may only be
appropriate for message-oriented transport (eg. SCTP) since
stream-oriented transport (eg. TCP) may not be able to recover the
message boundary once a length error has occurred.

1 files changed, 23 insertions, 9 deletions

diff --git a/lib/diameter/src/base/diameter_traffic.erl b/lib/diameter/src/base/diameter_traffic.erl
index 2f486861a2..0de3825943 100644
--- a/lib/diameter/src/base/diameter_traffic.erl
+++ b/lib/diameter/src/base/diameter_traffic.erl
@@ -309,21 +309,35 @@ request_cb(App,
 
 %% examine/1
 %%
-%% Look for errors in a decoded message. Length errors result in
-%% decode failure in diameter_codec.
+%% Look for errors in a decoded message. It's odd/unfortunate that
+%% 501[15] aren't protocol errors.
 
-examine(#diameter_packet{header = #diameter_header{version
-                                                   = ?DIAMETER_VERSION}}
-        = Pkt) ->
-    Pkt;
+%%   DIAMETER_INVALID_MESSAGE_LENGTH 5015
+%%
+%%      This error is returned when a request is received with an invalid
+%%      message length.
+
+examine(#diameter_packet{header = #diameter_header{length = Len},
+                         bin = Bin,
+                         errors = Es}
+        = Pkt)
+  when Len < 20;
+       0 /= Len rem 4;
+       8*Len /= bit_size(Bin) ->
+    Pkt#diameter_packet{errors = [5015 | Es]};
 
 %%   DIAMETER_UNSUPPORTED_VERSION       5011
 %%      This error is returned when a request was received, whose version
 %%      number is unsupported.
 
-examine(#diameter_packet{errors = Es} = Pkt) ->
-    Pkt#diameter_packet{errors = [5011 | Es]}.
-%% It's odd/unfortunate that this isn't a protocol error.
+examine(#diameter_packet{header = #diameter_header{version = V},
+                         errors = Es}
+        = Pkt)
+  when V /= ?DIAMETER_VERSION ->
+    Pkt#diameter_packet{errors = [5011 | Es]};
+
+examine(Pkt) ->
+    Pkt.
 
 %% request_cb/8