[removed] Is IP In One Of These Subnets?

Question

So I have ~12600 subnets:

eg. 123.123.208.0/20

and an IP.

I can use a SQLite Database or an array or whatever

There was a similar question asked

Answer 1

Convert the lower ip and the upper ip in the range to integers and store the range in the db then make sure both columns are indexed.

Off the top of my head (pseudo code):

function ipmap(w,x,y,z) {
  return 16777216*w + 65536*x + 256*y + z;
}

var masks = array[ipmap(128,0,0,0), ipmap(196,0,0,0), ..., ipmap(255,255,255,255)]

function lowrange(w, x, y, z, rangelength) {
  return ipmap(w, x, y, z) & masks[rangelength]
}

function hirange(w, x, y, z, rangelength) {
  return lowrange(w, x, y, z, ,rangelength) + ipmap(255,255,255,255) - masks[rangelength];
}

That ought to do it.

To find whether a particular ip falls in any of the ranges, convert it to an integer and do:

SELECT COUNT(*) FROM ipranges WHERE lowrange <= 1234567 AND 1234567 <= highrange

The query optimizer should be able to speed this up greatly.