Language choice [was Re: Symlinks]

Rik fbsdusers at rikrose.net
Tue Feb 12 16:32:37 GMT 2002


Hi all,

Just thought I'd drop in my hapennys-worth about the design ideas I've
had so far...

Well, I know some people won't like this, but I'm going to write my DNS
server in C, and be careful of strings and sizes of binary data. Indeed,
I will probably be passing size_t's around.

The architecture will/may be something like:

Master Process:
  Starts up any processes in hard-coded watch directory whose
  executables have appeared since the last check interval, or last
  recieved SIGCHLD.
  When a SIGCHLD is recieved, work out which child process died, reap
  it, and start up a new one.
TCP/UDP Listener:
  Listens to a port and accepts connections. When a new connection
  appears, accept it, and attach it to the stdin and stdout of a
  proccess that deals with the data 1 line (~= packet in this case) at a
  time. Multiplex the data.
Child Processes:
  These would actually handle the protocol for each section. These would
  be, eg a recursive resolver, an authoritative server, a zone transfer
  server, and so forth.

Well, that's *basically* how djbdns does things now. Possible
modifications include combining the TCP/UDP Listener with the Child
Processes, to avoid the fork()/exec() overhead. I'm currently (as I
type), thinking that I'd like to do that, and bring in a single threaded
kqueue/kevent (for FreeBSD, poll() for those that have it, select() for
those that don't have poll()) loop with nonblocking sockets.

There's a few other things I'm thinking about, now people have started
me thinking again (see what you started when you asked about wu-ftpd,
whoever it was!)

Uhm. Hm. Anyone wanna banter on IRC? #DeNSe on openprojects.net?

rik
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