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From: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
To: David Lamparter <equinox@diac24.net>
Cc: Rodrigo Moya <rodrigo.moya@collabora.co.uk>,
	David Miller <davem@davemloft.net>,
	javier@collabora.co.uk, eric.dumazet@gmail.com,
	lennart@poettering.net, kay.sievers@vrfy.org,
	alban.crequy@collabora.co.uk, bart.cerneels@collabora.co.uk,
	sjoerd.simons@collabora.co.uk, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/10] af_unix: add multicast and filtering features to AF_UNIX
Date: Tue, 28 Feb 2012 16:24:47 +0100	[thread overview]
Message-ID: <4F4CF1BF.7080503@collabora.co.uk> (raw)
In-Reply-To: <20120228142846.GD187520@jupiter.n2.diac24.net>

On 02/28/2012 03:28 PM, David Lamparter wrote:
> On Tue, Feb 28, 2012 at 11:47:39AM +0100, Rodrigo Moya wrote:
>> > - slow readers: dropping packets vs blocking the sender. Although
>> >   datagrams are not reliable on IP, datagrams on Unix sockets are
>> never
>> >   lost. So if one receiver has its buffer full the sender is blocked
>> > instead of dropping packets. That way we guarantee a reliable
>> > communication channel.
> 
> This sounds like a terribly nice way to f*ck the entire D-Bus system by
> having one broken (or malicious) desktop application. What's the
> intended way of coping with users that block the socket by not reading?
> 
> 
> -David L.

The problem is that D-bus expects a reliable transport method (TCP or
SOCK_STREAM Unix socks) but this is not the case with multicast Unix
sockets. Since our implementation is for SOCK_SEQPACKET and SOCK_DGRAM
socket types.

So, you have to either add another layer to the D-bus protocol to make
it reliable (acks, retransmissions, flow control, etc) or avoid losing
D-bus messages (by blocking the sender if one of the receivers has its
buffer full).

Regards,
Javier

  reply	other threads:[~2012-02-28 15:24 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-20 15:57 [PATCH 0/10] af_unix: add multicast and filtering features to AF_UNIX Javier Martinez Canillas
2012-02-20 15:57 ` [PATCH 01/10] af_unix: Documentation on multicast unix sockets Javier Martinez Canillas
2012-02-20 15:57 ` [PATCH 02/10] af_unix: Add constant for unix socket options level Javier Martinez Canillas
2012-02-20 15:57 ` [PATCH 03/10] af_unix: add setsockopt on unix sockets Javier Martinez Canillas
2012-02-20 16:20   ` David Miller
2012-02-20 19:13 ` [PATCH 0/10] af_unix: add multicast and filtering features to AF_UNIX Colin Walters
2012-02-21  8:07   ` Rodrigo Moya
2012-02-24 20:36 ` David Miller
2012-02-27 14:00   ` Javier Martinez Canillas
2012-02-27 19:05     ` David Miller
2012-02-28 10:47       ` Rodrigo Moya
2012-02-28 14:28         ` David Lamparter
2012-02-28 15:24           ` Javier Martinez Canillas [this message]
2012-02-28 16:33             ` Javier Martinez Canillas
2012-02-28 19:05         ` David Miller
2012-03-01 11:57           ` Javier Martinez Canillas
2012-03-01 12:26             ` Eric Dumazet
2012-03-01 12:33               ` David Laight
2012-03-01 12:50                 ` Rodrigo Moya
2012-03-01 12:59                   ` Eric Dumazet
2012-03-01 13:56                     ` Javier Martinez Canillas
2012-03-01 16:00                       ` Eric Dumazet
2012-03-01 16:02                       ` Luiz Augusto von Dentz
2012-03-01 17:06                         ` Javier Martinez Canillas
2012-03-01 17:59                         ` Eric Dumazet
2012-03-01 18:10                           ` Alan Cox
2012-03-01 19:02                           ` Javier Martinez Canillas
2012-03-01 19:29                             ` Javier Martinez Canillas
2012-03-01 18:53                         ` David Dillow
2012-03-01 20:55                       ` David Miller
2012-03-02  4:40                         ` Stephen Hemminger
2012-03-01 20:44               ` David Miller
2012-03-01 22:01                 ` Luiz Augusto von Dentz
2012-03-01 22:08                   ` David Miller
2012-03-02  8:39                     ` Luiz Augusto von Dentz
2012-03-02  8:55                       ` David Miller
2012-03-02  9:27                         ` Javier Martinez Canillas
2012-03-02  9:39                           ` David Miller
2012-03-02 13:13                           ` Eric Dumazet
2012-03-02 16:34                             ` Javier Martinez Canillas
2012-03-02 17:08                               ` Alan Cox
2012-03-05  8:38                                 ` Luiz Augusto von Dentz
2012-03-05 14:05                                   ` Martin Mares
2012-03-05 15:11                                     ` Javier Martinez Canillas
2012-03-05 15:49                                       ` Martin Mares
2012-03-05 18:55                           ` David Lamparter
2012-03-02 10:08                         ` Luiz Augusto von Dentz
2012-03-03 12:20                           ` Martin Mares
2012-03-02 22:19                         ` david
2012-03-01 12:57             ` Luiz Augusto von Dentz
2012-03-01 20:42             ` David Miller
  -- strict thread matches above, loose matches on Subject: below --
2012-03-01 14:25 Erik Hugne
2012-03-01 14:25 ` Erik Hugne
2012-03-01 17:18 ` Rodrigo Moya
2012-03-02  7:01   ` Ying Xue
     [not found]   ` <4F506ABC.8050807@windriver.com>
2012-03-05 15:49     ` Erik Hugne

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