Wireshark-dev: [Wireshark-dev] New syntax for range support in membership operator: tcp.port in
Hi,
Laura requested support for ranges for the "in" display filter operator
in bug 1480 which seems like a reasonable idea. I have a prototype patch
working here: https://code.wireshark.org/review/26945
The initial implementation converted "f in {a-b}" to "f >= a && f <= b",
but this turned out to be problematic when a field has multiple
occurrences. To solve this, I added a new ANY_IN_RANGE DVFM instruction
that checks each field against the range.
One remaining issue is the syntax. The proposed syntax looks a bit ugly
with negative numbers, and is also not implemented for things other than
numbers. It can also be ambiguous.
Example: find SMB server timezone within UTC-0700 and UTC-0400):
smb.server_timezone in {-420--240}
Example: find all hosts in range 10.0.0.10-10.0.0.60. The CIDR notation
cannot be used to match this, instead you need something verbose like:
(ip.src >= 10.0.0.10 and ip.src <= 10.0.0.60) or
(ip.dst >= 10.0.0.10 and ip.dst <= 10.0.0.60)
A potential shorter version (not supported at the moment):
ip.addr in {10.0.0.10-10.0.0.60}
Another issue: the filter "data.data==1-3" is interpreted as matching
bytes "0103" (because data.data is of type FT_BYTES). The display filter
"data.data in {1-3}" is currently ambiguous (previously it matched the
previous "==" filter, after my patch it becomes "a single byte in range
01 to 03"). One way to address this is to treat only "01:02:03" as byte
patterns and forbid "01-02-03".
With these cases, do you think that using "-" is a good range operator
for the set membership operator? An alternative range syntax suggestion
was proposed in doc/README.display_filter as:
(x in {a ... z})
Some possible ideas (I don't really like them to be honest):
tcp.srcport in { 80 1662 ... 1664 }
tcp.srcport in { 80 1662 .. 1664 }
tcp.srcport in { 80 [1662, 1664] }
tcp.srcport in { 80 range(1662, 1664) }
Feedback is welcome!
--
Kind regards,
Peter Wu
https://lekensteyn.nl
