hlandau / nccald

Namecoin calendar notification daemon (ICS, CalDAV)

nccald

nccald is a simple daemon to provide calendar notifications for Namecoin name expirations.

The daemon periodically queries a Namecoin Core instance using the name_list RPC command and can do one or both of the following:

• Generate an ICS calendar file listing names with their projected expiration dates
• Push to a CalDav server

Usage

Daemon command line arguments:

nccald
  -service.xyz=etc.
  -nccald.calmargin=72h             Interval of uncertainty to allow in projected expiration calculation.
  -nccald.calquantum=72h            Projected expiration time is rounded to a multiple of this time interval.
  -nccald.calqueryinterval=10m      Query interval.
  -nccald.icspath=...               Write ICS calendar file to this path if specified.
  -nccald.caldavurl=...             Specify URL of a CalDAV calendar resource to update a CalDAV calendar if desired.
  -nccald.caldavusername=...        Username to use for CalDAV authentication.
  -nccald.caldavpassword=...        Password to use for CalDAV authentication.
  -nccald.namecoinrpcaddress=...    Address of Namecoin RPC server (e.g. "127.0.0.1:8336").
  -nccald.namecoinrpcusername=...   Username to use for Namecoin RPC.
  -nccald.namecoinrpcpassword=...   Password to use for Namecoin RPC.
  -nccald.namecoinrpccookiepath=... Path to cookie file to use for Namecoin RPC.
  -nccald.once=1                    Write ICS file/update CalDAV once and exit.

When the ICS calendar file is written, the file ${PATH}.tmp is first written and renamed over the original file (thus writes are atomic but inode number does change); therefore you can use inotify to watch for changes to the ICS file if you like.

Here is example usage for generation of an ICS file periodically:

nccald -nccald.namecoinrpccookiepath=~/.namecoin/.cookie -nccald.icspath=~/namecoin.ics

Here is example usage for updating a CalDAV resource periodically. Note that the URL given should be to a CalDAV calendar resource:

nccald
  -nccald.namecoinrpccookiepath=~/.namecoin/.cookie
  -nccald.caldavurl=https://example.com/calendars/my-calendar/
  -nccald.caldavusername=calendaruser
  -nccald.caldavpassword=calendarpassword

You can use -nccald.once=1 if you want to run a cron job instead of a persistent daemon:

nccald -nccald.once=1 ...

For debug logging, pass -xlog.severity=debug.

For a full list of options, run nccald -help.

Calculation of expiration dates

Since Namecoin name expiration is based on block height, exact calculations of a chronological expiration time are not possible. nccald calculates a conservative (that is, early) expiration time based on configurable margin and quantum values.

The expiration date of a name is guessed based on assuming each block averages 10 minutes; then the margin duration is subtracted. Finally, the resulting time is rounded down to a multiple of the quantum duration; this is to ensure that the estimated expiry date does not constantly fluctuate between different values as the block height changes.

If you want to increase your safety margin of how far in advance you renew names, increase -nccald.calmargin. If you are noticing “date jump” in which a projected expiration keeps moving from one calendar day to another, increase -nccald.calquantum.

Licence

© 2021 Hugo Landau <[e-mail]>        GPLv3+ License