Saturday, September 4, 2010

New Deadwood snapshot: Non-A records now resolve

I guess not that many people are testing Deadwood.

Let me be honest about the type of testing I’m doing with Deadwood: I am testing Deadwood’s as a DNS server used for casual web surfing on today’s internet. That means that most of the queries done are A queries; I don’t do much testing with AAAA (IPv6) queries because, quite bluntly, my ISP doesn’t offer IPv6 service and I can think of only one site on the Internet with an AAAA record:

Likewise, I haven’t done any testing with MX records. I haven’t touched MX records at all because I’m not using Deadwood with a mail hub. So, it came as an unpleasant shock to me when I discovered last night that Deadwood hasn’t been properly resolving MX records for over a year.

In Deadwood 2.4.05 (released August 9, 2009), I added the ability to rotate resource records. Unknown to me, this feature broke Deadwood with any variable-length record, such as a MX record pair where the hostnames are of different lengths.

The advantage of using Deadwood’s robust string library with almost all of Deadwood’s DNS processing is that this bug did not result in any memory corruption or cause any other problems; the only issue has been that Deadwood would not resolve MX or other variable length records.

The idea that some freetards advocate that open source software is magically tested and that all bugs become shallow is nothing more than so much—how should I say this—mental masturbation. The author of Mailman, John Viega, points out how wrong this is in his excellent essay “The Myth of Open Source Security”.

Excuse me for the blunt wording, but I am a little frustrated right now: I have devoted a decade of my life to MaraDNS, and I haven’t even been able to get a job because of my hard work; while I have had a couple of interviews I would not have had because of MaraDNS, so far I have gotten no offers. Yes, those are interviews I would not had have if it weren’t for MaraDNS, and, yes, MaraDNS kept my skills from getting completely rusty during the ’00s when I was concentrating on learning Spanish and living in Mexico. But, looking back, I really wish I had spent more time learning C++ and object oriented programming and less time editing the Wikipedia or posting to /..

It looks like Deadwood isn’t getting much external testing; not one person saw Deadwood’s issue with MX records in the year Deadwood has had this bug. So, yeah, like everything else with MaraDNS, I’m responsible for just about all of the testing. This isn’t a complete loss; people have asked me in interviews about my testing methodology for MaraDNS.

I have just uploaded a snapshot which fixes the issue with rotating records like MX records:

As a side benefit, since I have fixed this issue, TTL aging and RR rotation now work with ANY records.

Next: Set up a test for this issue, as well as DNS compression tests for all of the resource record types MaraDNS supports. If I get time, I will also set up tests to make sure Deadwood correctly handles things like SRV records with compression pointers, and that Deadwood doesn’t compress SRV records.