Wireshark mailing list archives
Re: How do display filters work internally?
From: "Maynard, Chris" <Christopher.Maynard () GTECH COM>
Date: Mon, 23 Jan 2012 12:14:11 -0500
-----Original Message----- From: wireshark-dev-bounces () wireshark org [mailto:wireshark-dev- bounces () wireshark org] On Behalf Of Joerg Mayer Sent: Thursday, January 19, 2012 5:41 PM To: wireshark-dev () wireshark org Subject: [Wireshark-dev] How do display filters work internally? Hello List, I fail to understand how display filters work internally. I'm still trying to get my generic ip.addr filter working, but I seem to lack some understanding on how display filters work. It looks like putting an "alien" protocol filter into the hf array will work, as ip.version inside packet-ipv6.c shows: The field is shown and filterable. Putting the ip.addr field vom packet-ip.c into all uses of ipv4 addresses (everything of type FT_IPv4) will show it, but it won't be filterable (neither existence nor value). Can someone please fill in some info how display filtering works? Thanks Joerg --
I think the problem is that TRY_TO_FAKE_THIS_ITEM() has a return path such that the count for hf_ip_addr doesn't get incremented as it should. Attached is a patch that works for proto_tree_add_ipv4(). I made no attempt to "prettify" the patch; it's just a quick hack to get it to work, so cleanup is needed and proto_tree_add_item() still needs attention, as does proto_tree_add_ipv4_format_value() and proto_tree_add_ipv4_format(). I did test this with an "ip.addr" filter and it matched IP addresses in the IP protocol, but also with some bootp traffic. - Chris --
Attachment:
ip.addr.proto-v4.patch
Description: ip.addr.proto-v4.patch
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Current thread:
- How do display filters work internally? Joerg Mayer (Jan 19)
- Re: How do display filters work internally? Maynard, Chris (Jan 23)
- Re: How do display filters work internally? Chris Maynard (Jan 23)
- Re: How do display filters work internally? Maynard, Chris (Jan 23)