Lift restriction on upper case protocol display filter names

Unlike other header fields in filter expressions protocol names
cannot contain upper-case letters. Remove that restriction. This
should make start-up slightly faster as it remove an extra loop
for each protocol filter name.

This was added in 9ead15a6eb16be93559d71b4083948338ab9d26e but
I don't see a reason to have different rules for protocols and
fields, it seems the README.developer was just being vague and
conflating PROTOABBREV with PROTOFILTERNAME.

The recommendation for lower case is a style recommendation,
and it's a good one, but it should be applied uniformly. As
long as we are not enforcing this for all field filter values
there is no point in enforcing it just for protocol names and
actually it is detrimental, e.g:

hi2operations
HI2Operations.IRIsContent
HI2Operations.UUS1_Content_element
HI2Operations.iRIContent
HI2Operations.iRISequence
HI2Operations.IRIContent
HI2Operations.iRI_Begin_record_element
HI2Operations.iRI_End_record_element
HI2Operations.iRI_Continue_record_element
HI2Operations.iRI_Report_record_element
(...)

It's weird and unexpected to have this difference and there is
no technical reason to require it. What we should probably do
is not include the protocol name in the FIELDFILTERNAME and
have the registration mechanism append it to the PROTOFILTERNAME.

Also disallow leading '-' everywhere in filter names, not just
protocol filter names. It's a universal requirement.

1 files changed, 6 insertions, 20 deletions

diff --git a/epan/proto.c b/epan/proto.c
index 6f9efbc8ab..5b13e601e9 100644
--- a/epan/proto.c
+++ b/epan/proto.c
@@ -7363,21 +7363,9 @@ proto_tree_set_appendix(proto_tree *tree, tvbuff_t *tvb, gint start,
 static void
 check_valid_filter_name_or_fail(const char *filter_name)
 {
-	gboolean found_invalid = proto_check_field_name(filter_name);
-
-	/* Additionally forbid upper case characters. */
-	if (!found_invalid) {
-		for (guint i = 0; filter_name[i]; i++) {
-			if (g_ascii_isupper(filter_name[i])) {
-				found_invalid = TRUE;
-				break;
-			}
-		}
-	}
-
-	if (found_invalid) {
+	if (proto_check_field_name(filter_name) != '\0') {
 		ws_error("Protocol filter name \"%s\" has one or more invalid characters."
-			" Allowed are lower characters, digits, '-', '_' and non-repeating '.'."
+			" Allowed are letters, digits, '-', '_' and non-repeating '.'."
 			" This might be caused by an inappropriate plugin or a development error.", filter_name);
 	}
 
@@ -7386,12 +7374,6 @@ check_valid_filter_name_or_fail(const char *filter_name)
 		ws_error("Protocol filter name \"%s\" is invalid because it is a reserved keyword."
 			" This might be caused by an inappropriate plugin or a development error.", filter_name);
 	}
-
-	/* First character cannot be '-'. */
-	if (filter_name[0] == '-') {
-		ws_error("Protocol filter name \"%s\" cannot begin with '-'."
-			" This might be caused by an inappropriate plugin or a development error.", filter_name);
-	}
 }
 
 int
@@ -13168,6 +13150,10 @@ proto_check_field_name(const gchar *field_name)
 	const char *p = field_name;
 	guchar c = '.', lastc;
 
+	/* First character cannot be '-'. */
+	if (field_name[0] == '-')
+		return '-';
+
 	do {
 		lastc = c;
 		c = *(p++);