Return-Path: <cyrus@holtmann.org>
Subject: Re: bug? kernel does not send HCI Create Connection Cancel Command
 on  shutdown() or close() of a connecting rfcomm socket
From: Marcel Holtmann <marcel@holtmann.org>
To: Nick Pelly <npelly@google.com>
Cc: linux-bluetooth@vger.kernel.org
In-Reply-To: <35c90d960905191820g4e3ee434hfd0060815540a4e0@mail.gmail.com>
References: <35c90d960905191820g4e3ee434hfd0060815540a4e0@mail.gmail.com>
Content-Type: text/plain
Date: Tue, 19 May 2009 19:49:17 -0700
Message-Id: <1242787757.3147.13.camel@localhost.localdomain>
Mime-Version: 1.0
Sender: linux-bluetooth-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hi Nick,

> I found that neither close() nor shutdown() on a RFCOMM socket that is
> currently connecting will cause the kernel to send HCI Create
> Connection Cancel Command. This seems like a problem, since this means
> there is no way to cancel an outgoing connection - even in the single
> threaded case.
> 
> Ideally for our use case both shutdown() and close() would cause the
> Create Connection Cancel command to be sent.
> 
> It is easy to check this with a code snippet like:
> 
>     fd = _socket(PF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
>     flags = fcntl(fd, F_GETFL);
>     fcntl(fd, F_SETFL, flags | O_NONBLOCK);
>     connect(fd, (struct sockaddr *) &addr, sizeof(struct sockaddr));
> 
>     sleep(1);
>     shutdown(fd, SHUT_RDWR);
>     sleep(1);
>     close(fd);
> 
> Following this with hcidump you can see the Create Connection command
> sent, but it does not get canceled on close or shutdown.
> 
> 2009-05-19 17:55:16.098103 < HCI Command: Create Connection
> (0x01|0x0005) plen 13
>     bdaddr 00:11:22:33:44:55 ptype 0xcc18 rswitch 0x01 clkoffset 0x0000
>     Packet type: DM1 DM3 DM5 DH1 DH3 DH5
> 2009-05-19 17:55:16.118305 > HCI Event: Command Status (0x0f) plen 4
>     Create Connection (0x01|0x0005) status 0x00 ncmd 1
> 
> <--- shutdown()
> <--- close()
> 
> 2009-05-19 17:55:26.361744 > HCI Event: Connect Complete (0x03) plen 11
>     status 0x04 handle 1 bdaddr 00:11:22:33:44:55 type ACL encrypt 0x00
>     Error: Page Timeout
> 2009-05-19 17:55:33.119251 < HCI Command: Create Connection
> (0x01|0x0005) plen 13
>     bdaddr 00:11:22:33:44:55 ptype 0xcc18 rswitch 0x01 clkoffset 0x0000
>     Packet type: DM1 DM3 DM5 DH1 DH3 DH5
> 2009-05-19 17:55:33.139240 > HCI Event: Command Status (0x0f) plen 4
>     Create Connection (0x01|0x0005) status 0x00 ncmd 1
> 
> 
> Tested on 2.6.29.
> 
> Is this behavior intentional or is this a bug?

I know that I tested this massively with non-blocking sockets and there
is works perfectly fine. No idea why shutdown() or close() is not
catching this.

Please check with 2.6.30-rc6 kernel since the Simple Pairing changes
might have broken something here.

Regards

Marcel