JOINing based on whether an IP address is contained within a CIDR range?

["Jamie Tufnell" <diesql(at)googlemail(dot)com>]

Hi,

I am storing a log of HTTP requests in a database table (including IP address):

http_log: id(PK), path, time, ip

I have another table that contains CIDR ranges and names for them:

network_names: id(PK), cidr, name

Some example data for both tables:

network_names:
1, 192.168.0.0/24, 'Engineering'
2, 192.168.1.0/24, 'Media'
3, 192.168.2.0/24, 'Engineering'
4, 192.168.3.0/24, 'Accounting'
5, 192.168.4.0/24, 'Engineering'
6, 10.0.0.0/8, 'Engineering'

http_log:
1, '/index.html', 110000001, 192.168.0.47/32

2, '/index.html', 110000023, 200.1.2.3/32


3, '/index.html', 110000059, 1.2.3.4/32


4, '/index.html', 110000232, 192.168.2.1/32


5, '/index.html', 113919102, 192.168.1.39/32


6, '/index.html', 129101293, 10.2.2.4/32


7, '/index.html', 132828282, 192.168.4.2/32


Now, in trying to produce a report on this data, I've come up against an interesting (to me at least!) problem..

I basically want the same output as in http_log, but substituting the IP with the network name where available, 
i.e:

1, '/index.html', 110000001, Engineering
2, '/index.html', 110000023, 200.1.2.3/32

3, '/index.html', 110000059, 1.2.3.4/32

4, '/index.html', 110000232, Engineering

5, '/index.html', 113919102, Media

6, '/index.html', 129101293, Engineering

7, '/index.html', 132828282, Engineering

I'm wondering what the best way of doing this is (considering that http_log could have >100000 rows)  Is it possible to somehow JOIN using the <<= and >>= network operators?  Or would I have to iterate the network_names table manually with LOOP (or something) on every row of the http_log?

If anyone can share some advice, that would be great!

Thanks,
JST