Enable warnings on atypical conditions for the FILTER function (suggested by mmichelson on the -dev list).

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@246022 65c4cc65-6c06-0410-ace0-fbb531ad65f3

funcs/func_strings.c

@@ -603,6 +603,10 @@ static int filter(struct ast_channel *chan, const char *cmd, char *parse, char *
 		return -1;
 	}
 
+	if (args.allowed[0] == '"' && !ast_opt_dont_warn) {
+		ast_log(LOG_WARNING, "FILTER allowed characters includes the quote (\") character.  This may not be what you want.\n");
+	}
+
 	/* Expand ranges */
 	for (; *(args.allowed) && allowedlen < sizeof(allowed); ) {
 		char c1 = 0, c2 = 0;
@@ -617,6 +621,10 @@ static int filter(struct ast_channel *chan, const char *cmd, char *parse, char *
 				c2 = -1;
 			args.allowed += consumed + 1;
 
+			if ((c2 < c1 || c2 == -1) && !ast_opt_dont_warn) {
+				ast_log(LOG_WARNING, "Range wrapping in FILTER(%s,%s).  This may not be what you want.\n", parse, args.string);
+			}
+
 			/*!\note
 			 * Looks a little strange, until you realize that we can overflow
 			 * the size of a char.