netdev - Re: [PATCH 0/4] RFC: raw IPv6 address parsing in NFS client

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Message-Id: <BA7B3AE0-E0BA-4535-8641-5DC4A3A41F64@oracle.com>
Date:	Mon, 19 May 2008 10:15:44 -0400
From:	Chuck Lever <chuck.lever@...cle.com>
To:	Jeff Garzik <jeff@...zik.org>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH 0/4] RFC: raw IPv6 address parsing in NFS client

On May 18, 2008, at 10:13 PM, Jeff Garzik wrote:
> Chuck Lever wrote:
>> Hi-
>> I'm interested in some review of the following four patches which  
>> add to
>> the kernel's NFS client the ability to parse IPv6 addresses in  
>> presentation
>> format.
>> Namely, it adds the following:
>> 1.  If the user passes in an IPv6 address as the server name, the  
>> colons
>>    in the address will confuse the logic that splits the device name
>>    into a server hostname and an export path.   We'll use square  
>> brackets
>>    around IPv6 server addresses to "escape" the colons, as does  
>> Solaris.
>> 2.  If the user passes in a link-local IPv6 address as the server  
>> name,
>>    an interface index is also necessary.  We'll use the "%id"  
>> suffix on
>>    the address to pass in the index, and plant that in the sockaddr's
>>    sin6_scope_id field.
>> In addition to the following patches in email, a git repo with these
>> same patches already applied can be found here:
>> 	linux-nfs.org:exports/cel-2.6.git
>> The basic questions:
>> Are these reasonable conventions to follow?  Is the parsing logic  
>> adequate?
>> Is there anything I'm forgetting?
>
> I would take a look at the underlying components of glibc's  
> getnameinfo(), which must parse IPv6 addresses according to POSIX  
> specifications, IIRC.
>
> Comments:
>
> 1) bracket escaping seems reasonably common.  browsers and other  
> apps sometimes use that convention too.
>
> 2) an interface name rather than index should be used

If you give a raw IPv6 address with an interface name to mount.nfs, it  
passes the whole thing to getaddrinfo(3) which maps the name to an  
index. The address with index is then passed on to the kernel via  
mount(2) via the normal "addr=" mount option.

Is there a way the kernel can do that mapping for itself?

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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