(usagi-users 03426) Re: select() bug on IPv6 multicast SSM socket.

[Hoerdt Mickael <hoerdt@xxxxxxxxxxxxxxxxxxxxx>]

Ok the proof of the bug is now there :

1. download http://clarinet.u-strasbg.fr/~hoerdt/testselect.tgz
2. compile it (make).

This code contains testselect.c which :
    a. create two sockets so1 and so2, bind them and register them to
the same SSM
        channel.
    b. launch select() on the two sockets and print when data arrive.

by  default it register to the channel 2001:1::1 ff3e::1234, thats a
constant that you can
change. The behavior observed on my box is the following :

./test_select
2 multicast sockets ready for reading
so1 have data
so2 have data
1 multicast sockets ready for reading
so2 have data
1 multicast sockets ready for reading
so2 have data
1 multicast sockets ready for reading
so2 have data
1 multicast sockets ready for reading
so2 have data

As you  can observe, the first packet is well received, but the others
only arrive
at one socket.  I know that it is a very specific particular case, but I
need to have
this in my application (receiving on both sockets), because in my
application the
set of channels joined by sockets may be different over time.

Thanks,

Hoerdt Mickaël







Stig Venaas wrote:

>On Thu, Jun 23, 2005 at 09:35:15AM +0200, Hoerdt Mickael wrote:
>  
>
>>Hi,
>>
>>I have strange behavior in my code :
>>
>>I got two IPv6 UDP sockets, bound to the same port and listening to the
>>same SSM channel (INCLUDE mode). I am using select() to know when packets are coming on it. The
>>thing is that only one socket receive packets is it normal ? does multicast
>>toward sockets bound
>>to the same port and listening to the same group works ?
>>    
>>
>
>It works fine for me on 2.6.11 (without usagi) and also has before.
>Is your problem with select(), does select only include one of the
>sockets in the read set? Or are you indeed not receiving packets?
>
>I only tested ASM though,
>
>Stig
>
>
>  
>