site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com User-agent: Microsoft-Entourage/10.1.4.030702.0 Raj, Thank you for that information! The only reason why I thought the pkthdr_header had to be set was the comment in enetlognke that mentions "system panic". Maybe it is only a concern with Interface filters. -Allan "Raj Doshi" <admin@tacosw.com> wrote on 7/3/05 6:30 PM:
Hi,
I implemented an IP filter with injection like you are describing without ever modifying mbuf_pkthdr_header. Even when I made a copy of an mbuf and injected the copy instead of the original, I did not set the mbuf_pkthdr_header (although there are other fields that need to be set like checksum requested/performed in this case). So, I think the answer is no, you do not need to worry about mbuf_pkthdr_header in an IP filter. You should be able to inject a filtered mbuf, as is.
Raj Doshi
On Jul 1, 2005, at 8:27 PM, Allan Hoeltje wrote:
First off, thank you Quinn and Josh for the pointers you have given me so far.
Second, I need some more pointers!
I have been testing the enetlognke interface filter sample and mundged it into what I hope is the beginning of an IP filter.
The problem I am running into is that the mbuf_t data passed to my ipf_input_func (and ipf_output_func) always has a NULL mbuf_pkthdr_header.
For enetlognke this is OK since the interface filter enet_input_func is passed a reference to a frame header. There is even a comment that says: "Before we swallow the packet, we need to make sure that the very first mbuf has the pkthdr_header field set, else the system will panic when we inject the packet. The input routine is passed the frame_header pointer, so we can use this value to set as the pkthdr_header."
Is there some api I can use to get the frame header in my ipf_input_func? Does any of this matter for an IP filter?
Sorry if this is a dumb question but there is very little documentation and even less sample code for mbufs and kernel extensions.
Help!
-Allan
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