From: "Rémi Denis-Courmont" <rdenis@simphalempin•com>
To: Gerrit Renker <gerrit@erg•abdn.ac.uk>
Cc: Arnaldo Carvalho de Melo <acme@redhat•com>,
David Stevens <dlstevens@us•ibm.com>,
David Miller <davem@davemloft•net>,
dccp@vger•kernel.org, netdev@vger•kernel.org,
Ulrich Drepper <drepper@redhat•com>
Subject: Re: [RFC] [DCCP]: Deprecate SOCK_DCCP in favour of SOCK_DGRAM
Date: Tue, 13 May 2008 20:37:38 +0300 [thread overview]
Message-ID: <200805132037.39580.rdenis@simphalempin.com> (raw)
In-Reply-To: <20080513170325.GB11499@gerrit.erg.abdn.ac.uk>
Le Tuesday 13 May 2008 20:03:25 Gerrit Renker, vous avez écrit :
> Using work-arounds is brittle and frustrating when the API behaviour
> suddenly changes. My experience of using such a wrapper was:
>
> * it passed UDP(-Lite), TCP through without changing the socket type;
> * when passed DCCP, it set the socket type to 0, to avoid `ai_socktype
> not supported' getaddrinfo error;
> * this used to work fine until about January, when something in the
> lookup machinery for dual-stack hosts changed:
> - before, AF_UNSPEC + ai_socktype=0 put IPv6 first into the result list,
> - now the the result order is reversed (IPv4 sockets are returned first)
You're probably using a recent libc that applies RFC3484 _properly_. If you
still want IPv6 first, no matter what addresses the host has, I think the
AI_PASSIVE flag should do the trick. Then again, working around RFC3484
policy is _not_ a good idea.
As far as I am concerned, for DCCP, I (meaning VLC) currently use SOCK_STREAM,
and overrides the socktype and protocol fields in the socket() call
manually - so I don't get a TCP socjet.
In any case, getaddrinfo() should be patched to
1/ accept ai_socktype == SOCK_DCCP and ai_protocol == IPPROTO_DCCP,
2/ accept ai_socktype == SOCK_DCCP and ai_protocol == 0,
and set ai_protocol to IPPROTO_DCCP in the results,
3/ (perhaps?) accept ai_protocol == IPPROTO_DCCP and ai_socktype == 0,
and set ai_socktype to SOCK_DCCP in the results.
Similarly:
1/ accept ai_socktype == SOCK_DGRAM and ai_protocol == IPPROTO_UDPLITE,
2/ (intentionally omitted - keep normal UDP non-Lite behavior)
3/ (perhaps?) accept ai_protocol == IPPROTO_UDPLITE and ai_socktype == 0,
and set ai_socktype to SOCK_DGRAM in the results.
Voilà. Best to check this with Ulrich Drepper, no?
--
Rémi Denis-Courmont
http://www.remlab.net/
next prev parent reply other threads:[~2008-05-13 17:37 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-13 7:28 [RFC] [DCCP]: Deprecate SOCK_DCCP in favour of SOCK_DGRAM Gerrit Renker
2008-05-13 7:39 ` David Miller
2008-05-13 9:37 ` Gerrit Renker
2008-05-13 15:50 ` David Stevens
2008-05-13 16:23 ` Arnaldo Carvalho de Melo
2008-05-13 16:59 ` David Stevens
2008-05-13 17:06 ` Rémi Denis-Courmont
2008-05-13 17:34 ` Arnaldo Carvalho de Melo
2008-05-13 17:53 ` Arnaldo Carvalho de Melo
2008-05-13 17:33 ` Arnaldo Carvalho de Melo
2008-05-13 17:03 ` Gerrit Renker
2008-05-13 17:37 ` Rémi Denis-Courmont [this message]
2008-05-13 17:50 ` Arnaldo Carvalho de Melo
2008-05-13 19:14 ` Ulrich Drepper
2008-05-14 8:09 ` Gerrit Renker
2008-05-14 14:06 ` Ulrich Drepper
2008-05-14 14:45 ` Gerrit Renker
2008-05-14 16:06 ` Ulrich Drepper
2008-05-14 17:22 ` Gerrit Renker
2008-05-14 17:43 ` Ulrich Drepper
2008-05-14 18:00 ` Gerrit Renker
2008-05-14 17:39 ` Sridhar Samudrala
2008-05-14 17:49 ` Rémi Denis-Courmont
2008-05-14 18:07 ` Ulrich Drepper
2008-05-14 17:57 ` Ulrich Drepper
2008-05-14 17:47 ` Rémi Denis-Courmont
2008-05-14 18:06 ` Ulrich Drepper
2008-05-13 22:34 ` David Miller
2008-05-13 12:53 ` Remi Denis-Courmont
2008-05-13 13:46 ` Gerrit Renker
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