kernel network

[Ferner Cilloniz]

I have been tackling this today. This is what i have so far:

-------------------------------------------------------------------------
static int my_udp_send(struct thread *td, void *syscall_args)
{
    struct socket *sock = NULL;

    if( socreate(AF_INET, &sock, SOCK_DGRAM, 0, td->td_proc->p_ucred,
td) != 0 ) {
        uprintf("socreate() returned error\n");
        return -1;
    }

    struct sockaddr sa;
    sa.sa_len = sizeof(struct sockaddr_in);

    struct sockaddr_in *sin = (struct sockaddr_in *)&sa;
    sin->sin_family = AF_INET;
    inet_aton("192.168.2.2", (struct sockaddr_in *)&sin->sin_addr);
    sin->sin_port = htons(8080);
    sin->sin_len = sizeof(*sin);
    memset(sin->sin_zero, 0, sizeof(sin->sin_zero));

//    int soconnect_error = soconnect(sock, (struct sockaddr *)sin, td);
//    uprintf("soconnect(): %d\n", soconnect_error);

    struct mbuf *top = m_getclr(M_TRYWAIT, MT_CONTROL);

    // IP is 0
    int sosend_error = sosend(sock, (struct sockaddr *)sin, NULL, top,
NULL, 0, td);
    uprintf("sosend(): %d\n", sosend_error);

    soclose(sock);

    return 0;
}
-------------------------------------------------------------------------


However, when listening to my home network using wireshark, I filter out
everything but UDP packets with the 192.168.2.2 address on them. I'm
afraid to say that there aren't any packets showing.

Am i doing something wrong? Note, that I am not filling in the mbuf and
all the wacking casting done.

Thanks. 

On Tue, 2008-12-30 at 18:46 +0000, Robert Watson wrote:
> On Tue, 30 Dec 2008, Max Laier wrote:
> 
> > On Tuesday 30 December 2008 12:49:55 Ferner Cilloniz wrote:
> >
> >> I do not think I could ever be more tired of this topic but I cannot seem 
> >> to understand what to do. I have tried more about a month now to send 
> >> arbitrary UDP packets from a kernel module but cannot achieve it. I have 
> >> looked at udp_send but found that building a socket* was much to tedious. 
> >> Later i looked at in-kernel webservers (http://openketa.sourceforge.net/) 
> >> but could not find anything useful.
> >>
> >> Netgraph is a possibility, but there isn't any documentation on accessing 
> >> the network from kernel space.
> >>
> >> What do you all suggest?
> >
> > $ man 9 socket
> 
> Definitely the preferred solution, if it meets the application model.  Call 
> socreate(9) to allocate the socket, sobind(9) if required, calls to sosend(9) 
> to generate packets, and soclose(9) when done.  Direct calls to the 
> udp_output() and udp_send() functions won't work without a socket context, and 
> doing sosend(9) will isolate in-kernel consumers from future changes in UDP 
> internals.  ip_output() could be invoked directly to generate IP packets, but 
> won't allow you to easily receive replies, etc.
> 
> Robert N M Watson
> Computer Laboratory
> University of Cambridge
-- 
Cilloniz Bicchi, Ferner

Research Assistant
Dept. of Computer Sciences
The University of Texas at Austin
http://www.cs.utexas.edu/~fernercc
fernercc at cs.utexas.edu