kernel network

[Gerry Weaver]

_____  

From: Ferner Cilloniz [mailto:fernercc at gmail.com]
To: freebsd-net at freebsd.org
Sent: Tue, 30 Dec 2008 15:36:07 -0600
Subject: Re: kernel network

I tried another approach. The code is below. However, wireshark does not
  pick up anything happening. I don't know what is going on.
  
  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_in sin;
      sin.sin_len = sizeof(struct sockaddr_in);
      sin.sin_family = AF_INET;
      sin.sin_port = htons(8080);
      inet_aton("192.168.2.2", &sin.sin_addr);
  
      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;
  }
  
  
  
  
  On Tue, 2008-12-30 at 17:16 +0000, Ferner Cilloniz wrote:
  > 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
  
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  To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"Hello Ferner,

I believe you need a packet header in your mbuf. Try m_gethdr instead of 
m_getclr.

Thanks,
Gerry