57 lines
3.0 KiB
Plaintext
57 lines
3.0 KiB
Plaintext
PostgreSQL type extensions for IP and MAC addresses.
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$Id: README.ORIG,v 1.2 1998/06/16 05:35:10 momjian Exp $
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I needed to record IP and MAC level ethernet addresses in a data
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base, and I really didn't want to store them as plain strings, with
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no enforced error checking, so I put together the accompanying code
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as my first experiment with adding a data type to PostgreSQL. I
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then thought that this might be useful to others, both directly and
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as a very simple example of how to do this sort of thing, so here
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it is, in the hope that it will be useful.
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IP addresses are implemented as a 6 byte struct (this may be 1 byte
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more than is useful, but I figured that since it has to be at least 5,
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it might as well be an even number of bytes) that contains the four
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byte address and a mask width. The external representation of an IP
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address looks like '158.37.96.15/32' (or just '158.37.96.15', which is
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understood to mean the same thing). This address happens to be part
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of a subnet where I work; '158.37.96.0/24', which itself is a part of
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the larger subnet allocated to our site, which is '158.37.96.0/21',
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which again, if you go by the old book, is part of the class "B" net
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called '158.37.0.0/16'.
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Input and output functions are supplied, along with the "normal" <,
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<=, =, >=, > and <> operators, which all do what you expect. In
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addition, there is a function to check whether a given address is a
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member of a given subnet: ipaddr_in_net(addr, net), and functions to
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return the netmask and the broadcast address of a given network:
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ipaddr_mask(net) and ipaddr_bcast(net).
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MAC level ethernet addresses are implemented as a 6 byte struct that
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contains the address as unsigned chars. Several input forms are
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accepted; the following are all the same address: '08002b:010203',
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'08002b-010203', '0800.2b01.0203', '08-00-2b-01-02-03' and
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'08:00:2b:01:02:03'. Upper and lower case is accepted for the digits
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'a' through 'f'. Output is always in the latter of the given forms.
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As with IP addresses, input and output functions are supplied as well
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as the "normal" operators, which do what you expect. As an extra
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feature, a function macaddr_manuf() is defined, which returns the name
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of the manufacturer as a string. This is currently held in a
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hard-coded struct internal to the C module -- it might be smarter to
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put this information into an actual data base table, and look up the
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manufacturer there. (Another TODO, for both new data types, is to
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interface them to indices. If anyone can explain this to me in a way
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that is easier to understand than the current documentation, I would
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be most grateful!)
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I don't know what changes are needed to the Makefile for other systems
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than the one I'm running (NetBSD 1.3), but anyway: to install on a BSD
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system: fix the path names in the SQL files and the Makefile if you
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need to, then make, make install, slurp the SQL files into psql or
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whatever, and you're off. Enjoy!
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Bergen, Norway, 1998-01-31, Tom Ivar Helbekkmo (tih@Hamartun.Priv.NO).
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