UNISTIM: Refactor display address/control/tag handling

The 8 combinations of the display address, control, and tag were being
handled as 8 separate cases in `dissect_display_switch()`. This resulted
in duplicated, inconsistent code. Some paths resulted in bug #15219
while others did not have this problem.

I believe I have been able to combine them all into a single case branch
which handles each aspect correctly. I am not a UNISTIM expert and
welcome more knowledgeable reviewers.

Bug: 15219
Change-Id: Ie3eee8e19c10daab27c1df599ce0d03b52f69205
Reviewed-on: https://code.wireshark.org/review/37190
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 68 insertions, 244 deletions

diff --git a/plugins/epan/unistim/packet-unistim.c b/plugins/epan/unistim/packet-unistim.c
index e2fd688aa4..5f21fd14d8 100644
--- a/plugins/epan/unistim/packet-unistim.c
+++ b/plugins/epan/unistim/packet-unistim.c
@@ -981,269 +981,93 @@ dissect_display_switch(proto_tree *msg_tree,
          proto_tree_add_item(msg_tree,hf_display_use_date_format,tvb,offset,1,ENC_BIG_ENDIAN);
          offset+=1;msg_len-=1;
          break;
-      case 0x18:
-   /*address|no control|no tag|no*/
-         proto_tree_add_item(msg_tree,hf_generic_string,tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
-         break;
-      case 0x19:
-   /*address|yes control|no tag|no*/
-         address_tree=proto_tree_add_subtree(msg_tree,tvb,offset,0,ett_unistim,NULL,"Address");
-         address_byte=tvb_get_guint8(tvb,offset);
-         proto_tree_add_item(address_tree,hf_basic_bit_field,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_numeric,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_context,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_line,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_soft_key,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_soft_label,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-
-         if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG)==
-                          DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG){
-            proto_tree_add_item(address_tree,
-                                hf_display_write_address_softkey_id,
+   /*Address, control, tag: treat as bitmask to reduce code duplication*/
+      case 0x18: /*address|no  control|no  tag|no*/
+      case 0x19: /*address|yes control|no  tag|no*/
+      case 0x1A: /*address|no  control|yes tag|no*/
+      case 0x1B: /*address|yes control|yes tag|no*/
+      case 0x1C: /*address|no  control|no  tag|yes*/
+      case 0x1D: /*address|yes control|no  tag|yes*/
+      case 0x1E: /*address|no  control|yes tag|yes*/
+      case 0x1F: /*address|yes control|yes tag|yes*/
+#define F_ADDR 1
+#define F_CTRL 2
+#define F_TAG 4
+         if((display_cmd&F_ADDR)==F_ADDR){
+            address_tree=proto_tree_add_subtree(msg_tree,tvb,offset,0,ett_unistim,NULL,"Address Data");
+            address_byte=tvb_get_guint8(tvb,offset);
+            proto_tree_add_item(address_tree,hf_basic_bit_field,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
-         }
-         offset+=1;msg_len-=1;
-         if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG)==
-             DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG){
-            proto_tree_add_item(address_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
-            proto_tree_add_item(address_tree,
-                                hf_display_write_address_char_pos,
+            proto_tree_add_item(address_tree,hf_display_write_address_numeric,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
-            if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)!=
-                             DISPLAY_WRITE_ADDRESS_LINE_FLAG){
-               offset+=1;msg_len-=1;
-            }
-         }
-         if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)==
-             DISPLAY_WRITE_ADDRESS_LINE_FLAG){
-            proto_tree_add_item(address_tree,
-                                hf_display_write_address_line_number,
+            proto_tree_add_item(address_tree,hf_display_write_address_context,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
-            offset+=1;msg_len-=1;
-         }
-         if(msg_len>0){
-            /* I'm guessing this will work flakily at best */
-            proto_tree_add_item_ret_string(msg_tree,hf_generic_string,tvb,offset,msg_len, ENC_ASCII|ENC_NA, wmem_packet_scope(), &uinfo->string_data);
-         }
-
-         offset+=msg_len;
-         break;
-      case 0x1a:
-   /*address|no control|yes tag|no*/
-         proto_tree_add_item(msg_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_cursor_move,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_clear_left,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_clear_right,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_shift_left,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_shift_right,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_highlight,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1;msg_len-=1;
-         proto_tree_add_item(msg_tree,hf_generic_string,tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
-         proto_tree_add_item(msg_tree,hf_generic_string,
-                             tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
-         break;
-      case 0x1b:
-   /*address|yes control|yes tag|no*/
-         address_tree=proto_tree_add_subtree(msg_tree,tvb,offset,0,ett_unistim,NULL,"Address Data");
-         address_byte=tvb_get_guint8(tvb,offset);
-         proto_tree_add_item(address_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,
-                             hf_display_write_address_numeric,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,
-                             hf_display_write_address_context,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,
-                             hf_display_write_address_line,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,
-                             hf_display_write_address_soft_key,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,
-                             hf_display_write_address_soft_label,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG)==
-                          DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG){
-            proto_tree_add_item(address_tree,hf_display_write_address_softkey_id,
+            proto_tree_add_item(address_tree,hf_display_write_address_line,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
-            offset+=1; msg_len-=1;
-         }
-         if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG)==
-                          DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG){
-            proto_tree_add_item(address_tree,
-                                hf_display_write_address_char_pos,
+            proto_tree_add_item(address_tree,hf_display_write_address_soft_key,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
-            if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)!=
-                             DISPLAY_WRITE_ADDRESS_LINE_FLAG){
-               offset+=1;msg_len-=1;
-            }
-         }
-         if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)==
-                          DISPLAY_WRITE_ADDRESS_LINE_FLAG){
-            proto_tree_add_item(address_tree,
-                                hf_display_write_address_line_number,
+            proto_tree_add_item(address_tree,hf_display_write_address_soft_label,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
+
+            if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG)==
+                             DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG){
+               proto_tree_add_item(address_tree,
+                                   hf_display_write_address_softkey_id,
+                                   tvb,offset,1,ENC_BIG_ENDIAN);
+            }
             offset+=1;msg_len-=1;
-         }
-         proto_tree_add_item(msg_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_cursor_move,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_clear_left,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_clear_right,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_shift_left,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_shift_right,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_highlight,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1;msg_len-=1;
-         proto_tree_add_item(msg_tree,hf_generic_string,tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
-         break;
-      case 0x1c:
-   /*address|no control|no tag|yes*/
-         proto_tree_add_item(msg_tree,hf_display_write_tag,tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1;msg_len-=1;
-         proto_tree_add_item(msg_tree,hf_generic_string,tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
-         break;
-      case 0x1d:
-   /*address|yes control|no tag|yes*/
-         address_tree=proto_tree_add_subtree(msg_tree,tvb,offset,0,ett_unistim,NULL,"Address Data");
-         address_byte=tvb_get_guint8(tvb,offset);
-         proto_tree_add_item(address_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_numeric,tvb,
-                             offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_context,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_line,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_soft_key,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_soft_label,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG)==
-             DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG)
-            proto_tree_add_item(address_tree,
-                                hf_display_write_address_softkey_id,
-                                tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1; msg_len-=1;
-         if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG)==
-             DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG){
-            proto_tree_add_item(address_tree,
-                                hf_display_write_address_char_pos,
-                                tvb,offset,1,ENC_BIG_ENDIAN);
-            if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)!=
+            if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG)==
+                DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG){
+               proto_tree_add_item(address_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
+               proto_tree_add_item(address_tree,
+                                   hf_display_write_address_char_pos,
+                                   tvb,offset,1,ENC_BIG_ENDIAN);
+               if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)!=
+                                DISPLAY_WRITE_ADDRESS_LINE_FLAG){
+                  offset+=1;msg_len-=1;
+               }
+            }
+            if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)==
                 DISPLAY_WRITE_ADDRESS_LINE_FLAG){
+               proto_tree_add_item(address_tree,
+                                   hf_display_write_address_char_pos,
+                                   tvb,offset,1,ENC_BIG_ENDIAN);
+               proto_tree_add_item(address_tree,
+                                   hf_display_write_address_line_number,
+                                   tvb,offset,1,ENC_BIG_ENDIAN);
                offset+=1;msg_len-=1;
             }
          }
-         if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)==
-             DISPLAY_WRITE_ADDRESS_LINE_FLAG){
-            proto_tree_add_item(address_tree,hf_display_write_address_line_number,
+         if((display_cmd&F_CTRL)==F_CTRL){
+            proto_tree_add_item(msg_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
+            proto_tree_add_item(msg_tree,hf_display_write_cursor_move,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
-            offset+=1;msg_len-=1;
-         }
-         proto_tree_add_item(msg_tree,hf_generic_string,tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
-         break;
-      case 0x1e:
-   /*address|no control|yes tag|yes*/
-         proto_tree_add_item(msg_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_cursor_move,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_clear_left,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_clear_right,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_shift_left,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_shift_right,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_highlight,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1;msg_len-=1;
-
-         proto_tree_add_item(msg_tree,hf_generic_data,tvb,offset,msg_len,ENC_NA);
-         offset+=msg_len;
-         proto_tree_add_item(msg_tree,hf_display_write_tag,tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1;msg_len-=1;
-         proto_tree_add_item(msg_tree,hf_generic_string,tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
-         break;
-      case 0x1f:
-   /*address|yes control|yes tag|yes*/
-         address_tree=proto_tree_add_subtree(msg_tree,tvb,offset,0,ett_unistim,NULL,"Address");
-         address_byte=tvb_get_guint8(tvb,offset);
-         proto_tree_add_item(address_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_numeric,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_context,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_line,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_soft_key,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(address_tree,hf_display_write_address_soft_label,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG)==
-                          DISPLAY_WRITE_ADDRESS_SOFT_KEY_FLAG)
-            proto_tree_add_item(address_tree,hf_display_write_address_softkey_id,
+            proto_tree_add_item(msg_tree,hf_display_write_clear_left,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1; msg_len-=1;
-         proto_tree_add_item(msg_tree,hf_generic_string,
-                             tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
-         if((address_byte&DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG)==
-                          DISPLAY_WRITE_ADDRESS_SOFT_LABEL_FLAG){
-            proto_tree_add_item(address_tree,hf_display_write_address_char_pos,
+            proto_tree_add_item(msg_tree,hf_display_write_clear_right,
+                                tvb,offset,1,ENC_BIG_ENDIAN);
+            proto_tree_add_item(msg_tree,hf_display_write_shift_left,
+                                tvb,offset,1,ENC_BIG_ENDIAN);
+            proto_tree_add_item(msg_tree,hf_display_write_shift_right,
+                                tvb,offset,1,ENC_BIG_ENDIAN);
+            proto_tree_add_item(msg_tree,hf_display_write_highlight,
                                 tvb,offset,1,ENC_BIG_ENDIAN);
             offset+=1;msg_len-=1;
          }
-         if((address_byte&DISPLAY_WRITE_ADDRESS_LINE_FLAG)==
-                          DISPLAY_WRITE_ADDRESS_LINE_FLAG){
-            proto_tree_add_item(address_tree,
-                                hf_display_write_address_line_number,
-                                tvb,offset,1,ENC_BIG_ENDIAN);
+         if((display_cmd&F_TAG)==F_TAG){
+            proto_tree_add_item(msg_tree,hf_display_write_tag,tvb,offset,1,ENC_BIG_ENDIAN);
             offset+=1;msg_len-=1;
          }
-         proto_tree_add_item(msg_tree,hf_basic_bit_field,tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_cursor_move,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_clear_left,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_clear_right,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_shift_left,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_shift_right,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         proto_tree_add_item(msg_tree,hf_display_write_highlight,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1;msg_len-=1;
-         proto_tree_add_item(msg_tree,hf_display_write_tag,
-                             tvb,offset,1,ENC_BIG_ENDIAN);
-         offset+=1;msg_len-=1;
-         proto_tree_add_item(msg_tree,hf_generic_string,tvb,offset,msg_len,ENC_ASCII|ENC_NA);
-         offset+=msg_len;
+         /* whatever's left is the message */
+         if(msg_len>0){
+            /* I'm guessing this will work flakily at best */
+            proto_tree_add_item_ret_string(msg_tree,hf_generic_string,tvb,offset,msg_len, ENC_ASCII|ENC_NA, wmem_packet_scope(), &uinfo->string_data);
+            offset+=msg_len;
+         }
          break;
+#undef F_ADDR
+#undef F_CTRL
+#undef F_TAG
       case 0x20:
    /*Context Info Bar Format*/
          while(msg_len>0){