Writing a DNS server is easy

Posted Jan 23, 2003 12:42 UTC (Thu) by paulsheer (guest, #3925)
Parent article: A couple of alternative DNS servers

I actually find the whole DNS concept quite laughable. Admittedly, a recursive nameserver is a largish software project, but a master server is actually very simple to write. I wrote one in a weekend and its soon going to be the primary server for the .nis.za domain. It handles all common record types, and TCP and UDP queries, and its lightning fast.

I'll release the code after I add recursive queries.

I believe it has no exploits.

Writing a DNS server is easy

Posted Jan 23, 2003 20:18 UTC (Thu) by ahu (guest, #4298) [Link] (2 responses)

I'll speak to you a year from now :-) Anyhow, the recursive part is not that hard, the PowerDNS one is just 448 lines.

Re: Writing a DNS server is easy

Posted Jan 25, 2003 10:41 UTC (Sat) by sam (guest, #1329) [Link] (1 responses)

Well, depends on what sort of infastructure you already have in place. My recursive server is over 4000 lines long (!!!), but that includes the entire caching infastructure.

Does your caching infastructure have a method of removing elements from the cache so they no longer take up memory?

It took us months to get rid of all of the memory leaks in MaraDNS' cache.

BTW, Bert, I would like to applaud you for making Power DNS open source. It is good to see being realistic enough to realize that you are better off GPLing this package. You will still earn money by putting it on your résumé to impress people when the tech economy picks up again.

It is good to have competition among different open source DNS products; I am glad the "call to arms" for a non-BIND DNS server which has resulted in a number of implementations. Just two weeks ago, there were all of three non-BIND freely downloadable recursive DNS servers (my MaraDNS, pdnsd, and DjbDNS). All of a sudden, there are two more--five in total.

- Sam

Re: Writing a DNS server is easy

Posted Feb 3, 2003 18:46 UTC (Mon) by ahu (guest, #4298) [Link]

two words: use c++ :-) Saves heaps of typical C problems if done right, like memory leaks and the need to write btrees and whatnot

Writing a DNS server is easy

Posted Jan 25, 2003 10:14 UTC (Sat) by sam (guest, #1329) [Link]

Hmmm, well get back to us after you get compression working and after you have a working recursive DNS server. These are the two things which cause most would-be DNS implementers to give up on writing a DNS server. For example, moodns died when the author looked at what it took to get compression going. Dents died before the recursive part was finished. And so on.

I think it is apporoporate to quote a Slashdot posting I did recently:

Let me put it this way. Writing a DNS client (or a non-recursive DNS server) is sort of like Highlander I. Entertaining, really. You think to youself "Hey! That was easy! A recursive server can't be too bad!"
Well, writing a working recursive DNS server is like watching Highlander II. Suddenly, just as Highlander II changes your outlook on the entire Highlander franchise, writing a recursive DNS server changes your outlook on the entire DNS protocol.

- Sam