Re: IPv6 link-local addresses and init data type

On Tue, May 31, 2016 at 9:35 AM, Tom Dunstan <pgsql@tomd.cc> wrote:
>
>> On 31 May 2016, at 2:07 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>
>> The impression I have is that scopes are not very well standardized ---
>> eg, OS X reports things like "fe80::1%lo0" not just "%0".  If we could
>> get around that problem it would be worth doing.

The following is the content of IPV6 representation from RFC 4007

The following addresses
            fe80::1234 (on the 1st link of the node)            ff02::5678 (on the 5th link of the node)
ff08::9abc(on the 10th organization of the node) 
  would be represented as follows:
            fe80::1234%1            ff02::5678%5            ff08::9abc%10
  (Here we assume a natural translation from a zone index to the  <zone_id> part, where the Nth zone of any scope is
translatedinto  "N".) 
  If we use interface names as <zone_id>, those addresses could also be  represented as follows:
           fe80::1234%ne0           ff02::5678%pvc1.3           ff08::9abc%interface10

The digit and string both are considered as proper format.

>
> Yeah, we’d have to just store it as a string I think. That’s why I was happy to see that inet was already a varlena
butonly with known-length content. 

The % delimiter character is not only used at the end of the IPV6 address,
from the RFC document, it is possible as follows also.

fe80::%2/64

we need to handle both the scenarios,  it may not be a straight
forward to store the zone id data.

Regards,
Hari Babu
Fujitsu Australia