Re: ADDRINFO use [Was: Windows breakage with cr_net.h]

Samuel Thibault wrote:

>Hi
>
>Le lun 21 jun 2004 à 17:23:28 -0700, Mike Houston a tapoté sur son clavier :
>  
>
>>The other oddity is that the changes to support IPv6 seem to always kick 
>>us into using ADDRINFO on recent versions of Linux.  This works,
>>    
>>
>
>Of course it does, to support IPv6 whenever available. getaddrinfo()'s
>interface was specially design to always work: the dns lookup may
>report ipv4 and ipv6 addresses, getaddrinfo() gives them all. If an
>ipv6 address is given but doesn't work either because lack of support
>in the kernel (ENOAFSUPPORT) or for network reasons, the connection
>will revert back to ipv4.
>  
>
I understand why it works, I just thought it was odd to ALWAYS use it.

>  
>
>>but moves all streams to PF instead of AF.
>>    
>>
>
>PF / AF ??
>That means Protocol Family / Address Family.
>
>There's actually no difference between them, except maybe some minor
>differences in the numbering (there is none under linux for instance),
>and the *good* one to use for getaddrinfo in the hints structure *is*
>PF_something, since we tell the Protocol Family we'd like to use for
>conencting (here, unspecified). Then getaddrinfo may report
>AF_something to tell which address family it found. I just checked
>this once again in Gisèle Cizault's book "IPv6 Théorie et pratique"
>  
>
I don't have a problem with supporting IPv6 correctly, but some TOE's 
and most of the IP interception routines for highspeed networks only 
work if AF_INET is used.  For the later, you can use LD_PRELOAD to 
automatically kick some IP connections to SocketsGM, SDP, IP over 
Quadrics, etc.  But, this only works if AF_INET is used...  Since SDP 
has it's own layer now, this becomes a little less important.

>  
>
>>Things work, I just want to point out that this probably shouldn't
>>be default behavior.  We probably only really want to kick across
>>to PF streams when actually using IPv6 to connect.
>>    
>>
>
>Currently, we actually *precisely* use PF_INET when not using IPv6 to
>connect.
>  
>
Sorry for the misunderstanding here.  My point is whether we should use 
AF_INET in general and detect IPv6 another way.  Is anyone using IPv6?  
How often does anyone need to run IPv6 across a cluster?  Is it really 
just for remote stream support?

-Mike

>Regards,
>Samuel Thibault
>  
>


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