Re: New cast between inet/cidr and bytea

[Zoltan Boszormenyi <zb(at)cybertec(dot)at>]

Bruce Momjian írta:
> Zoltan Boszormenyi wrote:
>   
> > Hi,
> >
> > we at Cybertec have developed cast functions in C between
> > inet/cidr <-> bytea for a client and we would like to submit it.
> >
> > This is how it works:
> > - IPv4 inet/cidr value will return 4 bytes if the netmask covers all 32 
> > bits.
> >   It returns 5 bytes if the netmask is shorter than 32 bits.
> > - Similarly for IPv6, 12[+1] bytes is returned.
> > - 4, 5, 12 or 13 bytes long bytea values are converted
> >   to an inet/cidr value, the 5th or 13th byte is range-checked
> >   to be a valid netmask value.
> >
> > What are the requirements for it to be accepted
> > as a core cast function or as a contrib module?
> >     
>
> You discuss it on the hackers list.

That's what I am trying to.

>   Have you read the developer's FAQ? 
>   

Not yet in its entireness.

> What is the use case for such a cast?
>   
e.g.:
# select '192.168.0.1'::inet::bytea;
     bytea      
------------------
\300\250\000\001
(1 row)

# select '192.168.0.0/24'::inet::bytea;
       bytea        
----------------------
\300\250\000\000\030
(1 row)

# select decode('\\300\\250\\000\\001', 'escape')::inet;
  decode   
-------------
192.168.0.1
(1 row)

# select decode('\\300\\250\\000\\000\\030', 'escape')::inet;
    decode    
----------------
192.168.0.2/24
(1 row)

Similarly for IPv6 addresses.
The application doesn't want to parse the textual IP address
when all the parsing and checking intelligence is already there
in the inet/cidr type checks. The reverse when you pass in bytes
is only a logical extension.

--
----------------------------------
Zoltán Böszörményi
Cybertec Geschwinde & Schönig GmbH
http://www.postgresql.at/