Compiling on Windows, and a question of policy

Paul Wright
Mon Dec 2 11:51:48 UTC 2002

On Sat, 30 Nov 2002, Vernon Schryver wrote:

> > From: Paul Wright <>
> >                                       ...  I'd most likely do this by
> > compiling dccproc under Cygwin and then piping stuff to it.
> Beware of the difficulties presented by the use of UNIX mapped files
> and sockets in the DCC client code.  These problems can be overcome,
> but would be unwise to ignore them or to take shortcuts such as
> discarding the relevant DCC client code.

It looks as if Cygwin has some support for mmap. The files which use
mmap calls have compiled without complaint, anyway, although I don't
know whether they'll work or not. The thing that stops the build at the
moment is that Cygwin's limited IPv6 support has

struct in6_addr
        unsigned char s6_addr[16];

ie it does not have the union which enables the same data to be accessed
as an array of larger types. The dccproc autoconf seems to assume either
that this structure is not defined or that it contains the union. Not
being an expert with autoconf I'm not sure what to do to fix
this. Configuring with the option to disable IPv6 doesn't help.

> Anyone distributing a serious end-user DCC product must make provisions
> for DCC servers for that product or be seen as doing the same sort of
> thing that spammers do.  The difficulties of providing DCC servers for a
> few million end users is a major reason why I've not started what I've
> long talked about, something like a POP3/IMAP proxy version of dccproc.
> I've thought of suggesting to James Farmer that he consider porting
> dccproc into his product, but this problem of servers has stopped me.

Indeed, which was why I thought I'd ask first. I don't have the
resources to make such provisions.

There are people out there who are willing to donate bandwidth and CPU
time to provide DNS for various non-profit DNSBLs, such as the SBL or
SPEWS. From what you've said in the past, the bandwidth used by the DCC
client is not much greater than that used by running a DNSBL query.
Although running a server means responding to both clients and to flooding
from other servers, if the load is not too great, it's possible that
people might provide similar help with a DCC network. I think it is less
politically and legally risky to provide a DCC server than to provide a
mirror of a DNSBL.

The question is then whether it's acceptable to build a client which uses
the current public DCC servers in anticipation that some kind souls will
step into the breach if the client is too successful for its own good (if
they don't, the client risks being like a spammer itself, as you say).
AFAIK Razor has not yet had this problem despite a Windows client being
available, which might mean that overload is unlikely to happen in
practice. That said, Razor is not tracking every message.

> > ...
> > - The user's ISP should really be the one doing this. (But most of them
> >   aren't).
> The majority of the DCC checksums handled by the network of ~100 DCC
> servers now in the network are accumulated and compressed by servers
> run by ISPs for their customers.  (Note that I am not saying that most
> of those 100 servers are run by ISPs.)

The large ISPs in the UK don't seem to be very interested in spam
filtering, with the exception of BTopenworld, who've just signed up with
Brightmail. None of this is affecting me, since I'm running Linux and
can use dccproc, but it'd give me a warm feeling to see Windows users
able to effectively filter spam. The Register has written that spam
filtering is the new virus checking, which means there's an awful lot of
snake oil out there for Windows.

Paul Wright | |

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