Aiee :)
Hello!
On Mon, Sep 17, 2001 at 10:40:42AM -0700, Anil Kumar wrote:
> hi all,
> I wanted to know how I can write my own socket
> ioctl call. I have to add a new one for the socket
> option in the kernel.
Which socket family? (I suppose AF_INET about what follows)
[snip]
> But from the user program which ioctl function
> shall I use? Can I use sock_ioctl()? Or will ioctl()
You can't use sock_ioctl() from userland since it's a kernel
function; you have to use the usual ioctl(2) call.
Moroever sock_ioctl() is just a simple wrapper for the real
socket dependant ioctl call (through function pointers - as
usual within the kernel code).
> The command should also be implemented somewhere.
> I think af_inet.c for TCP/IP. But I want it to be
> protocol independent so that I can write different
> handlers for different protocols. So where do I define
> the new ioctl ??
Look at net/ipv4/af_inet.c, inet_ioctl() funtion [1]
That gets called for SOCK_DGRAM, SOCK_STREAM and SOCK_RAW
socket type, family AF_INET.
inet_ioctl() gets mapped upon socket creation (using the
right proto_ops{} variable - this rapresent a `layer'
between the `userspace view' of a socket and the first
in kernel `struct socket'.
If you think your custom ioctl call has to be protocol dependant,
you should go deeply, adding your code to the right .c file (i.e.
udp.c, raw.c, tcp_ipv4.c and so on).
Look at net/ipv4/af_inet.c to see how the struct proto gets filled
by this `protocol dependant' functions.
This rapresent the second layer between the kernel `struct socket'
and the `struct sock' datatypes.
Well, what I said is, as always, IMHO :)
Obviously feel free to correct this post if I said something of wrong,
not so accurate and so on, thanks!
> Thanx in advance.
> Anil
>
>
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bye bye
-- gg sullivan
[1]: What I said are just sorta of hints.
It's not so hard to track down something in the kernel, well, better,
it's not so hard to track down syscall flows in the kernel; grep will
really be your friend :)
--
Lorenzo Cavallaro `Gigi Sullivan' <sullivan@sikurezza.org>
Until I loved, life had no beauty;
I did not know I lived until I had loved. (Theodor Korner)
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Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
IRC Channel: irc.openprojects.net / #kernelnewbies
Web Page: http://www.kernelnewbies.org/
