gpgme_set_offline specifies if offline mode should
be used. Offline mode is disabled if yes is zero, and enabled
otherwise. By default, offline mode is disabled.
The details of the offline mode depend on the used protocol and its backend engine. It may eventually be extended to be more stricter and for example completely disable the use of Dirmngr for any engine.
For the CMS protocol the offline mode specifies whether Dirmngr shall be used to do additional validation that might require connecting external services (e.g., CRL / OCSP checks). The offline mode is used for all operations on this context. It has only an effect with GnuPG versions 2.1.6 or later.
For the OpenPGP protocol offline mode entirely disables the use of the Dirmngr and will thus guarantee that no network connections are done as part of an operation on this context. It has only an effect with GnuPG versions 2.1.23 or later.
For all other protocols the offline mode is currently ignored.
gpgme_get_offline returns 1 if offline
mode is enabled, and
0 if it is not, or if ctx is not a