Add some expert info to the MAC Control dissector

Partial-bug: 6121
Change-Id: If7a367671cf55793799e0d72f8846bd6fe2a2222
Reviewed-on: https://code.wireshark.org/review/3038
Reviewed-by: Evan Huus <eapache@gmail.com>

1 files changed, 35 insertions, 5 deletions

diff --git a/epan/dissectors/packet-maccontrol.c b/epan/dissectors/packet-maccontrol.c
index d6ccdecd78..f4132e82cc 100644
--- a/epan/dissectors/packet-maccontrol.c
+++ b/epan/dissectors/packet-maccontrol.c
@@ -32,6 +32,7 @@
 
 #include <glib.h>
 #include <epan/packet.h>
+#include <epan/expert.h>
 #include "packet-llc.h"
 #include <epan/etypes.h>
 
@@ -73,6 +74,10 @@ static gint ett_macctrl            = -1;
 static gint ett_macctrl_cbfc_enbv  = -1;
 static gint ett_macctrl_cbfc_pause_times = -1;
 
+static expert_field ei_macctrl_opcode = EI_INIT;
+static expert_field ei_macctrl_cbfc_enbv = EI_INIT;
+static expert_field ei_macctrl_dst_address = EI_INIT;
+
 static const int *macctrl_cbfc_enbv_list[] = {
   &hf_macctrl_cbfc_enbv_c0,
   &hf_macctrl_cbfc_enbv_c1,
@@ -123,12 +128,13 @@ static const value_string reg_flags_vals[] = {
   { 0, NULL }
 };
 
-
+static const guint8 dst_addr[] = {0x01, 0x80, 0xC2, 0x00, 0x00, 0x01};
+static const address macctrl_dst_address = { AT_ETHER, -1, 6, dst_addr};
 
 static void
 dissect_macctrl(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 {
-  proto_tree *ti;
+  proto_item *ti, *opcode_item;
   proto_tree *macctrl_tree = NULL;
   proto_tree *pause_times_tree = NULL;
   guint16     opcode;
@@ -143,13 +149,17 @@ dissect_macctrl(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
   ti = proto_tree_add_item(tree, proto_macctrl, tvb, 0, 46, ENC_NA);
   macctrl_tree = proto_item_add_subtree(ti, ett_macctrl);
 
-  proto_tree_add_uint(macctrl_tree, hf_macctrl_opcode, tvb, 0, 2, opcode);
+  opcode_item = proto_tree_add_uint(macctrl_tree, hf_macctrl_opcode, tvb, 0, 2, opcode);
   proto_tree_add_item(macctrl_tree, hf_macctrl_timestamp, tvb, 2, 4, ENC_BIG_ENDIAN);
   col_add_str(pinfo->cinfo, COL_INFO, val_to_str(opcode, opcode_vals, "Unknown"));
 
   switch (opcode) {
 
     case MACCTRL_PAUSE:
+      if (!addresses_equal(&pinfo->dst, &macctrl_dst_address)) {
+        expert_add_info(pinfo, opcode_item, &ei_macctrl_dst_address);
+      }
+
       pause_time = tvb_get_ntohs(tvb, 6);
       col_append_fstr(pinfo->cinfo, COL_INFO, ": pause_time: %u quanta",
                       pause_time);
@@ -207,8 +217,15 @@ dissect_macctrl(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
       break;
 
     case MACCTRL_CLASS_BASED_FLOW_CNTRL_PAUSE:
-      proto_tree_add_bitmask(macctrl_tree, tvb, 2, hf_macctrl_cbfc_enbv,
+      if (!addresses_equal(&pinfo->dst, &macctrl_dst_address)) {
+        expert_add_info(pinfo, opcode_item, &ei_macctrl_dst_address);
+      }
+
+      ti = proto_tree_add_bitmask(macctrl_tree, tvb, 2, hf_macctrl_cbfc_enbv,
                              ett_macctrl_cbfc_enbv, macctrl_cbfc_enbv_list, ENC_BIG_ENDIAN);
+      if (tvb_get_guint8(tvb, 2) != 0) {
+        expert_add_info(pinfo, ti, &ei_macctrl_cbfc_enbv);
+      }
 
       pause_times_tree = proto_tree_add_subtree(macctrl_tree, tvb, 4, 8*2, ett_macctrl_cbfc_pause_times, NULL, "CBFC Class Pause Times");
 
@@ -216,7 +233,9 @@ dissect_macctrl(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
         proto_tree_add_item(pause_times_tree, *macctrl_cbfc_pause_times_list[i], tvb, 4+i*2, 2, ENC_BIG_ENDIAN);
       }
       break;
-
+    default:
+      expert_add_info(pinfo, opcode_item, &ei_macctrl_opcode);
+     break;
   }
 }
 
@@ -338,9 +357,20 @@ proto_register_macctrl(void)
         &ett_macctrl_cbfc_enbv,
         &ett_macctrl_cbfc_pause_times
   };
+
+  static ei_register_info ei[] = {
+      { &ei_macctrl_opcode, { "macc.opcode.unknown", PI_PROTOCOL, PI_WARN, "Unknown opcode", EXPFILL }},
+      { &ei_macctrl_cbfc_enbv, { "macc.cbfc.enbv.not_zero", PI_PROTOCOL, PI_WARN, "8 MSbs of ENBV must be 0", EXPFILL }},
+      { &ei_macctrl_dst_address, { "macc.dst_address_invalid", PI_PROTOCOL, PI_WARN, "Destination address must be 01-80-C2-00-00-01", EXPFILL }},
+  };
+
+  expert_module_t* expert_macctrl;
+
   proto_macctrl = proto_register_protocol("MAC Control", "MACC", "macc");
   proto_register_field_array(proto_macctrl, hf, array_length(hf));
   proto_register_subtree_array(ett, array_length(ett));
+  expert_macctrl = expert_register_protocol(proto_macctrl);
+  expert_register_field_array(expert_macctrl, ei, array_length(ei));
 }
 
 void