3 ms·

interesting idea. if it's an excuse to play with something all for it. that being said: parsing isc dhcp lease files is a can of worms you probably don't want t

by mirceal 11y ago

interesting idea. if it's an excuse to play with something all for it. that being said: parsing isc dhcp lease files is a can of worms you probably don't want to open. to give you an example: what happens if the same machine appears twice in the lease file? what happens if some of the fields you are reading are missing? (let's say do you don't have a hostname)

hnlmorg 11y ago
I do a lazy dedup using a map, so only the latest entry will be stored. As all the data is output as ASCII, missing fields are just outputted as zero length strings. Those particular obstacles proved quiet easy to work around, but I fully expect there's other hidden traps I've overlooked. So I'm welcome to other suggestions for retrieving lease information :)
- mirceal 11y ago
  sure. as a side project there're nothing wrong with it :) I was just pointing out the pitfalls of lease parsing (i've been bitten by this over the course of time - it looks trivial to do until you look at what isc does under the covers) side questions: what happens with 50000 leases? what about 50000 subnets - do you have support for hierarchically displaying subnets :) how fast is the whole thing? can you handle malformed input?
  - hnlmorg 11y ago
    It's really basic at the moment so there's no support for hierarchical subnets, but it's something this that might suit this kind display. Performance wise, it's definitely not ready for any serious use. However there are some easy wins I didn't bother with that would dramatically speed things up (eg the leases file is read with each FUSE API request - which happens a lot. So I really should be running that as a separate thread that runs every x minutes and caches the object. if Im honest, scalability was a secondary concern. I was more interested in building a working proof of concept and sadly only had one afternoon to do it in. But I tried to keep the code clean enough (though you can be the judge of that) so it could be scaled up at a later date if needed.
    - mirceal 11y ago
      it's cool. the leap from prototype to production-ready is always a big one.

by mirceal 11y ago

hnlmorg 11y ago

I do a lazy dedup using a map, so only the latest entry will be stored. As all the data is output as ASCII, missing fields are just outputted as zero length strings. Those particular obstacles proved quiet easy to work around, but I fully expect there's other hidden traps I've overlooked. So I'm welcome to other suggestions for retrieving lease information :)

mirceal 11y ago
sure. as a side project there're nothing wrong with it :) I was just pointing out the pitfalls of lease parsing (i've been bitten by this over the course of time - it looks trivial to do until you look at what isc does under the covers) side questions: what happens with 50000 leases? what about 50000 subnets - do you have support for hierarchically displaying subnets :) how fast is the whole thing? can you handle malformed input?
- hnlmorg 11y ago
  It's really basic at the moment so there's no support for hierarchical subnets, but it's something this that might suit this kind display. Performance wise, it's definitely not ready for any serious use. However there are some easy wins I didn't bother with that would dramatically speed things up (eg the leases file is read with each FUSE API request - which happens a lot. So I really should be running that as a separate thread that runs every x minutes and caches the object. if Im honest, scalability was a secondary concern. I was more interested in building a working proof of concept and sadly only had one afternoon to do it in. But I tried to keep the code clean enough (though you can be the judge of that) so it could be scaled up at a later date if needed.
  - mirceal 11y ago
    it's cool. the leap from prototype to production-ready is always a big one.