we are currently trialing a new CalDAV implementation (based on SabreDAV) that also supports CardDAV. Its currently not packaged, but install is quite easy and documented in the readme of the repository located at Kopano · GitHub
There are quite some other ways to achieve what you wanted. We for example have a python module that can be easily use. See Kopano · GitHub for an example script that exports/imports .eml/.ics/.vcf files.