Date: Mon, 11 Jan 2010 16:12:09 -0800 From: Julian Elischer <julian@elischer.org> To: Maxim Ignatenko <gelraen.ua@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: ng_patch node Message-ID: <4B4BBE59.9010908@elischer.org> In-Reply-To: <ac42db051001111440p7b460641g855e4264d9433f58@mail.gmail.com> References: <ac42db051001111440p7b460641g855e4264d9433f58@mail.gmail.com>
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Maxim Ignatenko wrote:
> Hi,
> I've written netgraph node able to modify arbitrary (8|16|32)-bit
> unsigned integer in passing packets. Node applies one of =,+,-,&,| and
> ^ operations to number at given offset.
> Modification applied to each packet received on "in" hook. If "out"
> hook is connected - resulting packets passed on it, otherwise -
> returned back on "in" (for more easy use with ng_ipfw). Packets
> received on "out" hook passed on "in" unmodified.
> Node supports two control messages: "getconfig" and "setconfig".
> Configuration represented in next structure:
> struct ng_patch_config {
> uint32_t value; /* argument passed to requested operation */
> uint32_t offset; /* offset in bytes */
> uint32_t length; /* 1,2 or 4 bytes */
> uint32_t mode; /* operation code: 1 - "=", 2 - "+", 3 -
> "-", 4 - "&", 5 - "|", 6 - "^" */
> };
> Same names used in ASCII representation.
>
> I wanted to make ipfw able to modify TTL and ToS fields in IP packets,
> but after some generalization idea looked like described above.
I like it :-)
if you can provide a short man page, I can commit it for you.
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