RAW-sockets

RAW-sockets

[Oliver Bandel]

Hello,


how to use Eaw sockets from OCaml?

As in raw sockets I have to create the IP-header by myself
I'm wondering how.

IP normally uses 32Bit words, and the parts of it are not
necessarily byte or nibble oriented.
So I have to be able to set some bits directly.
But the OCaml int's is not complete 32 Bits.

How to use the raw sockets then?

Do I have to make a string (for highlevel socket functions)
or int's (read/write) and write that string or int-buffer
into the socket?
So that I write all bytes of the header as if it would be
normal data that I would write to a tcp-socket otherwise?

TIA,
  Oliver

Re: [Caml-list] RAW-sockets

[Oliver Bandel]

On Thu, May 18, 2006 at 05:27:45PM +0200, Oliver Bandel wrote:
> Hello,
> 
> 
> how to use Eaw sockets from OCaml?
> 
> As in raw sockets I have to create the IP-header by myself
> I'm wondering how.
> 
> IP normally uses 32Bit words, and the parts of it are not
> necessarily byte or nibble oriented.
> So I have to be able to set some bits directly.
> But the OCaml int's is not complete 32 Bits.
[...]

I have not found in the Unix-module an option for the sockets,
that is eaquivalent to the IP_HDRINCL option, as described
by Stevens in the Networking Programming Vol. I.

Isn't it possible in OCaml to create own IP-headers?
So, do I have to go back to C to e.g. write ICMP packets?


TIA,
  Oliver

Re: [Caml-list] RAW-sockets

[Oliver Bandel]

On Thu, May 18, 2006 at 05:50:07PM +0200, Oliver Bandel wrote:
> On Thu, May 18, 2006 at 05:27:45PM +0200, Oliver Bandel wrote:
> > Hello,
> > 
> > 
> > how to use Eaw sockets from OCaml?
> > 
> > As in raw sockets I have to create the IP-header by myself
> > I'm wondering how.
> > 
> > IP normally uses 32Bit words, and the parts of it are not
> > necessarily byte or nibble oriented.
> > So I have to be able to set some bits directly.
> > But the OCaml int's is not complete 32 Bits.
> [...]
> 
> I have not found in the Unix-module an option for the sockets,
> that is eaquivalent to the IP_HDRINCL option, as described
> by Stevens in the Networking Programming Vol. I.
> 
> Isn't it possible in OCaml to create own IP-headers?
> So, do I have to go back to C to e.g. write ICMP packets?

Or will protocol = 1 (ICMP) automagically set up all IP-specific
stuff?
(But if so: how RAW can one work with that?)


TIA,
  Oliver

Re: [Caml-list] RAW-sockets

[Oliver Bandel]

On Thu, May 18, 2006 at 10:36:25AM -0600, William D. Neumann wrote:
> On Thu, 18 May 2006, Oliver Bandel wrote:
> 
> >>how to use Eaw sockets from OCaml?
> >>
> >>As in raw sockets I have to create the IP-header by myself
> >>I'm wondering how.
> >>
> >>IP normally uses 32Bit words, and the parts of it are not
> >>necessarily byte or nibble oriented.
> >>So I have to be able to set some bits directly.
> >>But the OCaml int's is not complete 32 Bits.
> >[...]
> >
> >I have not found in the Unix-module an option for the sockets,
> >that is eaquivalent to the IP_HDRINCL option, as described
> >by Stevens in the Networking Programming Vol. I.
> >
> >Isn't it possible in OCaml to create own IP-headers?
> >So, do I have to go back to C to e.g. write ICMP packets?
> 
> No.  Just create a string in OCaml and use that.  Here's a (possibly 
> awful) hunk of code I wrote for creating ICMP packets.  Take a look at it 
> and see how I did things.
[...]

OK, thanks for that impression...
...but soooo much code for this?

Seems that it's easier to do it in C. :(


I will look at your code in more detail later,
but at first look, it was a little shock. :(

Maybe you have implemented more functionality than I need
and so what I was looking for is some lines of code only.
But nevertheless it's god to have his, so I can reason
about how to do some ICMP-based stuff.


Best Regards,
       Oliver

Re: [Caml-list] RAW-sockets

[Oliver Bandel]

On Fri, May 19, 2006 at 12:09:31PM +1200, Jonathan Roewen wrote:
> >IP normally uses 32Bit words, and the parts of it are not
> >necessarily byte or nibble oriented.
> >So I have to be able to set some bits directly.
> >But the OCaml int's is not complete 32 Bits.
> >
> >How to use the raw sockets then?
> >
> >Do I have to make a string (for highlevel socket functions)
> >or int's (read/write) and write that string or int-buffer
> >into the socket?
> >So that I write all bytes of the header as if it would be
> >normal data that I would write to a tcp-socket otherwise?
> 
> There are various approaches :-) Extlib has a nice IO module which has
> functions for writing  32-bit ints (using a 31-bit int when that extra
> bit isn't needed or a proper int32). I found that module quite useful
> for writing code that's a bit shorter/simpler for network packet
> generation.
> 
> You can use some other interesting approaches like representing your
> packet to be constructed as a list. I did that for DST's netstack :-)
> Can't say whether it's better or worse -- just different.

Well, I also could use C-functions (externals).

But I don't know HOW OCaml handle's the IP-stuff.

I don't know if - when using protocoll 1 (ICMP) for example,
if the IP-header will be generated automatically by OCaml.
It seems that it will be handled this way, but I have not seen
anything about this in the reference manual.

Do I have to write the IP-header by myself or not?

No documentation about if IP_HDRINCL is used internally or not.

Some more verbosity of the refman could help here.

Ciao,
   Oliver

Re: [Caml-list] RAW-sockets

[Oliver Bandel]

Hi,

On Thu, May 18, 2006 at 10:36:25AM -0600, William D. Neumann wrote:
> On Thu, 18 May 2006, Oliver Bandel wrote:
> 
> >>how to use Eaw sockets from OCaml?
> >>
> >>As in raw sockets I have to create the IP-header by myself
> >>I'm wondering how.
> >>
> >>IP normally uses 32Bit words, and the parts of it are not
> >>necessarily byte or nibble oriented.
> >>So I have to be able to set some bits directly.
> >>But the OCaml int's is not complete 32 Bits.
> >[...]
> >
> >I have not found in the Unix-module an option for the sockets,
> >that is eaquivalent to the IP_HDRINCL option, as described
> >by Stevens in the Networking Programming Vol. I.
> >
> >Isn't it possible in OCaml to create own IP-headers?
> >So, do I have to go back to C to e.g. write ICMP packets?
> 
> No.  Just create a string in OCaml and use that.  Here's a (possibly 
> awful) hunk of code I wrote for creating ICMP packets.  Take a look at it 
> and see how I did things.
> 
> (************************************************************************
> *
> *  icmp.ml
> *
> *
> *  Created by William D. Neumann on 10 Mar 2006.
> *  Copyright (c) 2006 William D. Neumann. All rights reserved.
> *
> ************************************************************************)
> 
> 
> (*p
> \setlength{\parindent}{0pt}
> \usepackage{amsmath,amsthm}
> \usepackage{amsfonts}
> *)
> 
> (*
> This is [icmp.ml]\footnote{Copyright (c) 2006 William D. Neumann. All 
> rights reserved.}, an OCaml program that implements a simple library for 
> working with ICMP packets.
> *)
[...]

It's nice that you have embedded LaTeX-code in your comments.
With which tool do you generate your documentation?
If there is such a LP-tool I also would use it, if freely available.


Ciao,
   Oliver

Re: [Caml-list] RAW-sockets

[Oliver Bandel]

On Fri, May 19, 2006 at 06:16:12PM +1200, Jonathan Roewen wrote:
> >But I don't know HOW OCaml handle's the IP-stuff.
> >
> >I don't know if - when using protocoll 1 (ICMP) for example,
> >if the IP-header will be generated automatically by OCaml.
> >It seems that it will be handled this way, but I have not seen
> >anything about this in the reference manual.
> >
> >Do I have to write the IP-header by myself or not?
> 
> Best way to find out: make your packet and send it and see what
> happens :-) Ethereal is most valuable in determining if your packets
> are well crafted :) Sometimes just doing it is easiest way to know or
> not ;-)

I can try sending my network garbage to the windows-PCs in this network here ;-)

Are their reactions also valuable in determining what my ip-packets look like? ;-)

Ciao,
   Oliver

Re: [Caml-list] RAW-sockets

[William D. Neumann]

On Fri, 19 May 2006, Oliver Bandel wrote:

> It's nice that you have embedded LaTeX-code in your comments.
> With which tool do you generate your documentation?
> If there is such a LP-tool I also would use it, if freely available.

I use ocamlweb <http://www.lri.fr/~filliatr/ocamlweb/>.

William D. Neumann

---

"There's just so many extra children, we could just feed the
children to these tigers.  We don't need them, we're not doing 
anything with them.

Tigers are noble and sleek; children are loud and messy."

         -- Neko Case

Life is unfair.  Kill yourself or get over it.
 	-- Black Box Recorder

Re: [Caml-list] RAW-sockets

[Oliver Bandel]

On Fri, May 19, 2006 at 06:27:48PM +1200, Jonathan Roewen wrote:
> >I can try sending my network garbage to the windows-PCs in this network 
> >here ;-)
> >
> >Are their reactions also valuable in determining what my ip-packets look 
> >like? ;-)
> 
> Possibly ;-) I think ethereal can listen on loopback with Ethereal so
> you don't need to send over the network and annoy other PCs ;-)

But I prefer to have a documentation that tells me what is going on,
before I have to do experiments...

If you know the answer how it behaves, it would be nice to throw it in here.
This then could be added to the reference manual.

Thanks,
   Oliver