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). Here the offline mode
only affects the keylist mode
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