On Friday, June 14, 2002, at 06:04 , Mat Harrison wrote:
[..]
> actually, it should only be 1-254 inclusive as 255 is reserved for
> broadcast or other special addresses (sometimes not used atall).
> oficially the 255 node it ignored.
that is actually a "dangerous" assertion to make. Since it basically
is only true in the case of well managed class "C" address blocks...
{the assertion is non-sensical in class "A" address space, and in
CIDR blocks... }
http://www.wetware.com/drieux/pbl/Net/simpleDotQuad.txt
the problem here is the question
"valid IP address"
which if all we mean is 'does it comply with the RFC791
specification of the range of four octets that are dot
separated then we need merely prove that assertion. In the code I
present above - I hope folks see that this really is sorta
a three pass problem -
a) does it comply with the basic
/^(\d+)\.(\d+)\.(\d+)\.(\d+)$/
pattern of being a 'dotQuad'
b) is each octet in range of 0..255
c) the funky part if you want to get into things
like worry about it being a loop back, an RFC 1918,
a broadcast, a multi-cast....
folks may wish to remember that while addresses like
0.0.0.0
and 127.0.0.1 may not be their pet fave ID_ADDR's - there are
others that they should be aware of as well.
remember from things like RFC1918 that
10.0.0.0 - 10.255.255.255 (10/8 prefix)
172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
192.168.0.0 - 192.168.255.255 (192.168/16 prefix)
designate the IP_ADDR space that is not accessible on the
internet itself....
cf: http://www.faqs.org/rfcs/rfc1918.html
We could of course go back and consult say RFC 791....
ciao
drieux
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