DelphinusDNS Blog
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August 20th, 2022
I have added cookies to dddctl query and committed the code. If you are using
dddctl to sign zones make sure you adjust this script
if you're using it. It greps (with -v) for '^;;' and with this change it
will possibly produce misoutput. It should grep -v for '^;'. I had to update
all my signing scripts too. Cheers!
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August 14th, 2022
A config change took place, anything downloaded and built after this date
needs new configs. Check out the commit message.
Some will rejoice perhaps at this. I'm glad I listened to Ricardo.
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August 13th, 2022
Before a configspecifying an axfrport would look like this:
options "some options" {
...
}
axfrport "10053";
...
This has been changed:
options "some options" {
axfrport 10053;
...
}
...
So I moved this option into the proper options block. There is also another
change called "strictaxfr;" in options. If you set this, you must have an
authenticating key before it spits back anything. If you don't it will hang up.
Otherwise the behaviour is as before plain non-authenticated (non-TSIG) AXFR's
would go through.
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August 13th, 2022
I just skimmed over this RFC. I think everything is done right. Drop me an
email if you see something from the implementation aspect that is wrong.
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July 15th, 2022
Whenever I code I build up stress with it. Right now I don't need more
stress as I'm soaking in serenity. Maybe in the future I'll get back at
doing DNS Updates, but it isn't in the foreseeable future. To those who
have been looking forward to this, I hate to disappoint you, but the
program is good as it is even without DNS Updates, I feel it's nearly
finished and doing the last few touches won't affect it much. Have a
happy holiday season all, stay safe.
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July 3rd, 2022
Just so you know I have replaced my profile picture with a self portrait.
Enjoy!
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June 26th, 2022
I'm sitting here in my parents living room writing this. It's been two weeks
since I committed any code and it'll likely be anoter two weeks before I start
committing again. The outside temperatures are sheerly too hot and as most
germans I do not, and my family does not own an air conditioner. The
temperatures are expected to hit 36C soon and have been doing so in the past
two weeks. Though while I'm not coding I can think around what I want to do
and write a blog article or something. So I thought I'd write about my
inspiration for writing this DNS server.
Back around 1996 I bought a book by
W.R. Stevens on UNIX Network Programming and bought followup books ever since.
The 2 volume set of the 2nd edition was what inspired me directly to write a
DNS server. All the foundations were laid in the book and I occasionally
used the book (one is already falling apart) as a reference on socket code.
So who is W.R. Stevens? He was a professor and worked at an observatory for
astronomy. All the things pretty well that interest me, he did it.
Unfortunately he died before Y2K which made his books so much more a legend.
After partially reading his books on network programming I concluded that this
is the foundation for building a dns server with udp, tcp and even raw sockets.
Which is what delphinusdnsd uses, it explains well known ports and ephemeral
ports, it explains connecting UDP sockets and so on. Thanks Mr. Stevens for
guiding me maybe we'll meet some day in the after-life.
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June 16th, 2022
I just want you to know that I haven't given up. We're approaching the
warmest part of the year and for me that means little coding. I wrote
to someone recently that I center my best coding around the equinoxes
with some additional coding near the winter solstice. In the summer the
trend is to chill on IRC or whatever and wait out the heat. I do have
some minor things to do which aren't really DNS Updates related (forwarder
giving me gripes) so you may see something there in the next few weeks.
Have a great summer!
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June 6th, 2022
Today I put in guard pages between slots in the three major shared memory
regions. These shared memory regions usually transfer packet metadata,
cache and full packet data. They are contiguous regions that I changed
guard pages on between slots (I hope slots is the right term here). It
looks a little like this:
start of memory ------> +------------------------+
//slot #0 //
// //
guardpage (pagesize) -> +------------------------+
+------------------------+
//slot #1 //
// //
guardpage (pagesize) -> +------------------------+
+------------------------+
//slot #2 //
... (to slot 199 or 399)
This ensures that at no time you can overrun a slot's boundary as you'll hit
a guard page. I changed the page protection with mprotect() to PROT_NONE, so
even reading from this area is akin to reading from non-allocated memory and
will signal 15 afaik.
I worked on this today because I previously worked on send_to_parser() which
is a routine
to send a DNS raw packet to the sandbox'ed parser process. Right now we have
a limitation of 16K or something in the imsg framework to send data to this
parser process. I plan on increasing this to the DNS maximum of 64K and do it
with shared memory which will speed up things (memory is the fastest way of
IPC (when shared)). We just gotta get the locking right, right now we have
a ghetto lock which isn't really a lock. I think I may create a file where
delphinusdnsd will serialize around a file lock. This should be ultra safe.
Anyhow this relates to the DNS Updates work that I'm slowly easing into.
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June 3rd, 2022
I had a bit of a shocker the other day. I made a 12,000 RR zone and wanted it
to be axfr'ed. But the replicant would not take it. I was stunned. I hoped
that I wouldn't have to repair code in this moment. After a few tries and
nothing. Then I remembered I had put in a hack around to a peculiar change
in AXFR and called it "replicant-axfr-old-behaviour" and similar on the
primary "primary-axfr-old-behaviour". This behaviour had something to do
with copying back the question of the AXFR. Judging by the comment in the
code it seems that new behaviour is not to copy the question header. Anyhow
needless to say I had this flag set on the primary but not the replicant thus
it failed copying. When synced it worked immediately. Yes I admit I totally
forgot about this feature. I will remove it in the future release (probably
at 1.7 time, granted I don't forget *smile*).
I'll be adding probably another 20,000 RR's to this particular zone and it'll
be a great test to see how well AXFR's work.
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