Re: Divert sockets no longer behave like connected (SS_ISCONNECTED is removed from so->so_state)

From: Gleb Smirnoff (glebius_at_freebsd.org)
Date: 12/16/04

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    Date: Thu, 16 Dec 2004 16:07:15 +0300
To: dvoinikov@kazna.ru

    On Thu, Dec 16, 2004 at 09:49:17AM +0500, ??????? ????????? wrote:
    ?> I'm having this application (VPN daemon) which
    ?> uses divert sockets for sending stuff http://www.targeted.org/nest/
    ?> It worked fine under 5.3-RELEASE but broke after
    ?> recent upgrade to FreeBSD 5.3-STABLE.
    ?>
    ?> An attempt to send() via divert socket now returns
    ?> EDESTADDRREQ "Destination address required". Digging
    ?> up the CVS revealed this:
    ?> http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netinet/ip_divert.c
    ?> Quote:
    ?> > Revision 1.98.2.1 / (download) - annotate - [select for diffs], Tue Nov 23 15:30:02 2004 UTC (3 weeks ago) by glebius
    ?> > Branch: RELENG_5
    ?> > - Since divert protocol is not connection oriented, remove SS_ISCONNECTED flag
    ?> > from divert sockets.
    ?>
    ?> Also relevant is this message by Gleb Smirnoff:
    ?> http://www.freebsd.org/cgi/getmsg.cgi?fetch=50544+0+/usr/local/www/db/text/2004/freebsd-net/20041121.freebsd-net
    ?> Quote:
    ?> > So, the real change suggested is to remove SS_ISCONNECTED from so->so_state. All
    ?> > other changes are its logical consequences.
    ?> > What was idea of that SS_ISCONNECTED flag always set? I can't find any problems we
    ?> > can get by removing this code.
    ?>
    ?> Well, I'm having one - my application stopped working.

    I'm sorry that this change hurt you. I didn't have possibility to find
    all divert(4) consumers.

    ?> Also, quote from man divert:
    ?>
    ?> > Packets are written as either incom-
    ?> > ing or outgoing: if write(2) or send(2) is used to deliver the packet
    ?> > ... skip ...
    ?> > then the packet is treated as if it were outgoing

    Yes. sosend() catches this case before entering protocol specific send method.
    I should update manpage.

    ?> My case exactly, but this no longer holds.
    ?>
    ?> What am I supposed to do now ? Modify my application ? Actually I already
    ?> did that, by switching to sendto(), but just wanted to make sure this
    ?> divert sockets semantics change is intented and not spontaneous.

    It was intended. Actually the protocol is not connection-oriented and addr
    should be supplied with each write. This was not a-clean-up-only change.
    We have a kernel module - ng_ksocket, which ignores destaddr for connected
    sockets. This lead to some problems because in divert the address is actually
    required. 

    -- 
Totus tuus, Glebius.
GLEBIUS-RIPN GLEB-RIPE
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