ng_patch node

[Maxim Ignatenko]

2010/1/12 Julian Elischer <julian at elischer.org>:
> 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.
>

I'll try to do this in few days, thanks :)