52 lines
2.8 KiB
Plaintext
52 lines
2.8 KiB
Plaintext
PostgreSQL type extensions for IP and MAC addresses.
|
|
---------------------------------------------------
|
|
|
|
I needed to record IP and MAC level ethernet addresses in a data
|
|
base, and I really didn't want to store them as plain strings, with
|
|
no enforced error checking, so I put together the accompanying code
|
|
as my first experiment with adding a data type to PostgreSQL. I
|
|
then thought that this might be useful to others, both directly and
|
|
as a very simple example of how to do this sort of thing, so here
|
|
it is, in the hope that it will be useful.
|
|
|
|
IP addresses are implemented as an 8 byte struct (this may well be
|
|
more than is useful, but I figured that since it has to be at least 5,
|
|
it might as well round well) that contains the four bytes of address
|
|
and a mask width. Thus, a node address looks like '158.37.96.15/32'
|
|
(or just '158.37.96.15', which is understood to mean the same thing).
|
|
This address happens to be part of a subnet where I work;
|
|
'158.37.96.0/24', which itself is a part of the larger subnet
|
|
allocated to our institution, which is '158.37.96.0/21', which again,
|
|
if you go by the book, is part of the class "B" net '158.37.0.0/16'.
|
|
|
|
Input and output functions are supplied, along with the "normal" <,
|
|
<=, =, >=, > and <> operators, which all do what you expect, and the
|
|
similarity operator ~~, which checks whether two given addresses are
|
|
either the same, or, failing that, whether one is a subnet
|
|
specification and the other an address (or a smaller subnet) within
|
|
that. Good for picking out records with addresses in a given subnet:
|
|
note that '158.37.96.0/21' spans '158.37.96.0' to '158.37.103.255',
|
|
which is not all that easily handled in its external representation.
|
|
|
|
MAC level ethernet addresses are also implemented as an 8 byte struct
|
|
(I wish I knew what alignment needs are actually present -- I'm just
|
|
not taking any chances here) that contains the address as unsigned
|
|
chars. Several input forms are accepted: the following are all the
|
|
same address: '08002b:010203', '08002b-010203', '0800.2b01.0203',
|
|
'08-00-2b-01-02-03' and '08:00:2b:01:02:03'. Upper and lower case is
|
|
accepted for the digits 'a' through 'f'. Output is always in the
|
|
latter of the given forms.
|
|
|
|
Input and output functions are supplied, along with the = and <>
|
|
operators, which do what you expect, and the similarity operator ~~,
|
|
which checks whether two given addresses belong to hardware from the
|
|
same manufacturer (first three bytes the same, that is). As an extra
|
|
feature, a function macaddr_manuf() is defined, which returns the name
|
|
of the manufacturer as a string.
|
|
|
|
To install: fix the path names in the SQL files and the Makefile if
|
|
you need to, then make, make install, slurp the SQL files into psql or
|
|
whatever, and you're off. Enjoy!
|
|
|
|
Bergen, Norway, 1998-01-11, Tom Ivar Helbekkmo (tih@Hamartun.Priv.NO).
|