dfilter: Add support for literal strings with null bytes

Before:
    Filter: frame matches "abc\x00def"
    dftest: \x00 (NUL byte) cannot be used with a regular string.
    	frame matches "abc\x00def"
    	                  ^~~~
    Filter: _ws.ftypes.string == "a string with a \0 byte"
    dftest: \0 (NUL byte) cannot be used with a regular string.
    	_ws.ftypes.string == "a string with a \0 byte"
    	                                      ^~

After:
    Filter: frame matches "abc\x00def"

    Syntax tree:
     0 TEST_MATCHES:
       1 FIELD(frame)
       1 PCRE(abc\0def)

    Instructions:
    00000 READ_TREE		frame -> reg#0
    00001 IF_FALSE_GOTO	3
    00002 ANY_MATCHES	reg#0 matches abc\0def
    00003 RETURN

    Filter: _ws.ftypes.string == "a string with a \0 byte"

    Syntax tree:
     0 TEST_ANY_EQ:
       1 FIELD(_ws.ftypes.string)
       1 FVALUE("a string with a \0 byte" <FT_STRING>)

    Instructions:
    00000 READ_TREE		_ws.ftypes.string -> reg#0
    00001 IF_FALSE_GOTO	3
    00002 ANY_EQ		reg#0 == "a string with a \0 byte" <FT_STRING>
    00003 RETURN

Fixes issue #16156.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/suite_dfilter/group_membership.py b/test/suite_dfilter/group_membership.py
index e3d1f37711..0b5392183a 100644
--- a/test/suite_dfilter/group_membership.py
+++ b/test/suite_dfilter/group_membership.py
@@ -86,7 +86,7 @@ class case_membership(unittest.TestCase):
 
     def test_membership_11_bad_rhs_string(self, checkDFilterFail):
         dfilter = 'frame.number in {1, "foo"}'
-        error = '"foo" cannot be converted to Unsigned integer, 4 bytes.'
+        error = 'Unsigned integer (4 bytes) cannot be converted from a string'
         checkDFilterFail(dfilter, error)
 
     def test_membership_12_value_string(self, checkDFilterCount):