Problem with network example of Ocaml book

Problem with network example of Ocaml book

[Harald Schmidt]

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Hi all,

I worked through the network example (page 629) of the the Ocaml book, and
don't know what's going wrong with the last statement. I am using Ocaml
under cygwin / WinXP.

I know, EINVAL means invalid argument, but as far as I read s_descr is used
as an abstract file descriptor. Is this wrong?

 
- ----------------------------------------------------------------------------
- -------------------------------------------------
let my_name = Unix.gethostname ();;
let my_entry_byname = Unix.gethostbyname my_name;;
let my_addr = my_entry_byname.Unix.h_addr_list.(0);;
let my_entry_byaddr = Unix.gethostbyaddr my_addr;;
let my_full_name = my_entry_byaddr.Unix.h_name;;
let s_descr = Unix.socket Unix.PF_INET Unix.SOCK_STREAM 0;;
let (addr_in, p_num) =
  match Unix.getsockname s_descr with
      Unix.ADDR_INET (a,n) -> (a,n)
    | _ -> failwith "not INET";;

# val my_entry_byname : Unix.host_entry =
  {Unix.h_name = "CNCHZUR2497"; Unix.h_aliases = [||];
   Unix.h_addrtype = Unix.PF_INET; Unix.h_addr_list = [|<abstr>; <abstr>|]}
# val my_addr : Unix.inet_addr = <abstr>
# val my_entry_byaddr : Unix.host_entry =
  {Unix.h_name = "CNCHZUR2497"; Unix.h_aliases = [||];
   Unix.h_addrtype = Unix.PF_INET; Unix.h_addr_list = [|<abstr>|]}
# val my_full_name : string = "CNCHZUR2497"
# val s_descr : Unix.file_descr = <abstr>
#       Exception: Unix.Unix_error (Unix.EINVAL, "getsockname", "").
# 
 
- ----------------------------------------------------------------------------
- -------------------------------------------------

By the way: where can I find the domain_of function of page 630. Here is the
code I used from the book:


Harald


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Re: [Caml-list] Problem with network example of Ocaml book

[Gerd Stolpmann]

The socket is not bound, so getsockname cannot return anything.
After Unix.bind or Unix.connect the socket will have a "name",
i.e. be bound to a port.

Gerd

Harald Schmidt said:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Hi all,
>
> I worked through the network example (page 629) of the the Ocaml book, and
> don't know what's going wrong with the last statement. I am using Ocaml
> under cygwin / WinXP.
>
> I know, EINVAL means invalid argument, but as far as I read s_descr is
> used
> as an abstract file descriptor. Is this wrong?
>
>
> -
> ----------------------------------------------------------------------------
> - -------------------------------------------------
> let my_name = Unix.gethostname ();;
> let my_entry_byname = Unix.gethostbyname my_name;;
> let my_addr = my_entry_byname.Unix.h_addr_list.(0);;
> let my_entry_byaddr = Unix.gethostbyaddr my_addr;;
> let my_full_name = my_entry_byaddr.Unix.h_name;;
> let s_descr = Unix.socket Unix.PF_INET Unix.SOCK_STREAM 0;;
> let (addr_in, p_num) =
>   match Unix.getsockname s_descr with
>       Unix.ADDR_INET (a,n) -> (a,n)
>     | _ -> failwith "not INET";;
>
> # val my_entry_byname : Unix.host_entry =
>   {Unix.h_name = "CNCHZUR2497"; Unix.h_aliases = [||];
>    Unix.h_addrtype = Unix.PF_INET; Unix.h_addr_list = [|<abstr>;
> <abstr>|]}
> # val my_addr : Unix.inet_addr = <abstr>
> # val my_entry_byaddr : Unix.host_entry =
>   {Unix.h_name = "CNCHZUR2497"; Unix.h_aliases = [||];
>    Unix.h_addrtype = Unix.PF_INET; Unix.h_addr_list = [|<abstr>|]}
> # val my_full_name : string = "CNCHZUR2497"
> # val s_descr : Unix.file_descr = <abstr>
> #       Exception: Unix.Unix_error (Unix.EINVAL, "getsockname", "").
> #
>
> -
> ----------------------------------------------------------------------------
> - -------------------------------------------------
>
> By the way: where can I find the domain_of function of page 630. Here is
> the
> code I used from the book:
>
>
> Harald
>
>
> -----BEGIN PGP SIGNATURE-----
> Version: PGP Desktop 9.0.1 (Build 2185)
>
> iQA/AwUBQ3stzKW2pktsM+Z9EQKiawCg33hDISm9FUVuJIKF2oFiQJLdhIsAoLE3
> fOf8ojkhqDaz47CqeERZdO64
> =AsBR
> -----END PGP SIGNATURE-----
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>


------------------------------------------------------------
Gerd Stolpmann * Viktoriastr. 45 * 64293 Darmstadt * Germany
gerd@gerd-stolpmann.de          http://www.gerd-stolpmann.de
------------------------------------------------------------

Re: [Caml-list] Problem with network example of Ocaml book

[William D. Neumann]

On Wed, 16 Nov 2005, Harald Schmidt wrote:

> I worked through the network example (page 629) of the the Ocaml book, and
> don't know what's going wrong with the last statement. I am using Ocaml
> under cygwin / WinXP.
>
> I know, EINVAL means invalid argument, but as far as I read s_descr is used
> as an abstract file descriptor. Is this wrong?

Well, this works fine on my OS X and Linux machines, so I'm guessing that 
it has something to do with cygwin.  Unfortunately I don't know enough 
about it to provide much help...

> By the way: where can I find the domain_of function of page 630. Here is the
> code I used from the book:

Do you mean the one in the "A Generic Server" section (page 632 in my 
copy)?  If so, I have no idea where theirs comes from, but you can use 
the Unix.domain_of_socket function in the Unix library.

William D. Neumann

---

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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."

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