Add BASE_NO_DISPLAY_VALUE to allow field value to not be shown.

There are times when byte arrays don't want to show their value
in the packet tree or there is a field that is the "header" of
a subtree where showing the field value distracts from the tree
display.  For these cases, BASE_NO_DISPLAY_VALUE can be used
to not display the value.

Change-Id: I8c9f1f57cd2e663dbee07e2289e7f5e1f22d1e32
Reviewed-on: https://code.wireshark.org/review/19479
Reviewed-by: Michael Mann <mmann78@netscape.net>

3 files changed, 28 insertions, 17 deletions

diff --git a/doc/README.dissector b/doc/README.dissector
index a3ae632e22..911fd78889 100644
--- a/doc/README.dissector
+++ b/doc/README.dissector
@@ -117,7 +117,7 @@ FIELDDISPLAY    --For FT_UINT{8,16,24,32,40,48,56,64} and
                   BASE_DEC, BASE_HEX, BASE_OCT, BASE_DEC_HEX, BASE_HEX_DEC,
                   BASE_CUSTOM, or BASE_NONE, possibly ORed with
                   BASE_RANGE_STRING, BASE_EXT_STRING, BASE_VAL64_STRING,
-                  BASE_ALLOW_ZERO or BASE_UNIT_STRING
+                  BASE_ALLOW_ZERO, BASE_UNIT_STRING or BASE_NO_DISPLAY_VALUE
 
                   BASE_NONE may be used with a non-NULL FIELDCONVERT when the
                   numeric value of the field itself is not of significance to
@@ -126,6 +126,11 @@ FIELDDISPLAY    --For FT_UINT{8,16,24,32,40,48,56,64} and
                   user in the protocol decode nor is it used when preparing
                   filters for the field in question.
 
+                  BASE_NO_DISPLAY_VALUE will just display the field name with
+                  no value.  It is intended for byte arrays (FT_BYTES) or
+                  header fields above a subtree.  The value will still be
+                  filterable, just not displayed.
+
                 --For FT_UINT16:
 
                   BASE_PT_UDP, BASE_PT_TCP, BASE_PT_DCCP or BASE_PT_SCTP
diff --git a/epan/proto.c b/epan/proto.c
index fc67163d66..ceb74c6f1e 100644
--- a/epan/proto.c
+++ b/epan/proto.c
@@ -7198,8 +7198,10 @@ label_fill(char *label_str, gsize pos, const header_field_info *hfinfo, const ch
 
 	/* "%s: %s", hfinfo->name, text */
 	name_pos = pos = label_concat(label_str, pos, hfinfo->name);
-	pos = label_concat(label_str, pos, ": ");
-	pos = label_concat(label_str, pos, text ? text : "(null)");
+	if (!(hfinfo->display & BASE_NO_DISPLAY_VALUE)) {
+		pos = label_concat(label_str, pos, ": ");
+		pos = label_concat(label_str, pos, text ? text : "(null)");
+	}
 
 	if (pos >= ITEM_LABEL_LENGTH) {
 		/* Uh oh, we don't have enough room. Tell the user that the field is truncated. */
@@ -7216,15 +7218,17 @@ label_fill_descr(char *label_str, gsize pos, const header_field_info *hfinfo, co
 
 	/* "%s: %s (%s)", hfinfo->name, text, descr */
 	name_pos = pos = label_concat(label_str, pos, hfinfo->name);
-	pos = label_concat(label_str, pos, ": ");
-	if (hfinfo->display & BASE_UNIT_STRING) {
-		pos = label_concat(label_str, pos, descr ? descr : "(null)");
-		pos = label_concat(label_str, pos, text ? text : "(null)");
-	} else {
-		pos = label_concat(label_str, pos, text ? text : "(null)");
-		pos = label_concat(label_str, pos, " (");
-		pos = label_concat(label_str, pos, descr ? descr : "(null)");
-		pos = label_concat(label_str, pos, ")");
+	if (!(hfinfo->display & BASE_NO_DISPLAY_VALUE)) {
+		pos = label_concat(label_str, pos, ": ");
+		if (hfinfo->display & BASE_UNIT_STRING) {
+			pos = label_concat(label_str, pos, descr ? descr : "(null)");
+			pos = label_concat(label_str, pos, text ? text : "(null)");
+		} else {
+			pos = label_concat(label_str, pos, text ? text : "(null)");
+			pos = label_concat(label_str, pos, " (");
+			pos = label_concat(label_str, pos, descr ? descr : "(null)");
+			pos = label_concat(label_str, pos, ")");
+		}
 	}
 
 	if (pos >= ITEM_LABEL_LENGTH) {
diff --git a/epan/proto.h b/epan/proto.h
index 30f6111109..ed4b6971e6 100644
--- a/epan/proto.h
+++ b/epan/proto.h
@@ -547,11 +547,13 @@ typedef enum {
 
 /* Following constants have to be ORed with a field_display_e when dissector
  * want to use specials value-string MACROs for a header_field_info */
-#define BASE_RANGE_STRING 0x100
-#define BASE_EXT_STRING   0x200
-#define BASE_VAL64_STRING 0x400
-#define BASE_ALLOW_ZERO   0x800  /**< Display <none> instead of <MISSING> for zero sized byte array */
-#define BASE_UNIT_STRING  0x1000  /**< Add unit text to the field value */
+#define BASE_RANGE_STRING       0x0100
+#define BASE_EXT_STRING         0x0200
+#define BASE_VAL64_STRING       0x0400
+#define BASE_ALLOW_ZERO         0x0800  /**< Display <none> instead of <MISSING> for zero sized byte array */
+#define BASE_UNIT_STRING        0x1000  /**< Add unit text to the field value */
+#define BASE_NO_DISPLAY_VALUE   0x2000  /**< Just display the field name with no value.  Intended for
+                                             byte arrays or header fields above a subtree */
 
 /** BASE_ values that cause the field value to be displayed twice */
 #define IS_BASE_DUAL(b) ((b)==BASE_DEC_HEX||(b)==BASE_HEX_DEC)