Re: bug? kernel does not send HCI Create Connection Cancel Command on shutdown() or close() of a connecting rfcomm socket

[Nick Pelly <npelly@google.com>]

On Tue, May 19, 2009 at 7:49 PM, Marcel Holtmann <marcel@holtmann.org> wrote:
> 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.

I tested on the following kernels:

Android 2.6.27 (2.6.27 + several bluetooth-next.git patches)
Android 2.6.29 (2.6.29 + several bluetooth-next.git patches)
2.6.28 (Ubuntu 9.10)

All with the same results.

I don't have easy access to a 2.6.30 kernel right now.

Thanks for letting us know this is not intentional behavior.

Nick