For the libpq-oauth module to eventually make use of the
PGoauthBearerRequest API, it needs some additional functionality: the
derived Issuer ID for the authorization server needs to be provided, and
error messages need to be built without relying on PGconn internals.
These features seem useful for application hooks, too, so that they
don't each have to reinvent the wheel.
The original plan was for additions to PGoauthBearerRequest to be made
without a version bump to the PGauthData type. Applications would simply
check a LIBPQ_HAS_* macro at compile time to decide whether they could
use the new features. That theoretically works for applications linked
against libpq, since it's not safe to downgrade libpq from the version
you've compiled against.
We've since found that this strategy won't work for plugins, due to a
complication first noticed during the libpq-oauth module split: it's
normal for a plugin on disk to be *newer* than the libpq that's loading
it, because you might have upgraded your installation while an
application was running. (In other words, a plugin architecture causes
the compile-time and run-time dependency arrows to point in opposite
directions, so plugins won't be able to rely on the LIBPQ_HAS_* macros
to determine what APIs are available to them.)
Instead, extend the original PGoauthBearerRequest (now retroactively
referred to as "v1" in the code) with a v2 subclass-style struct. When
an application implements and accepts PQAUTHDATA_OAUTH_BEARER_TOKEN_V2,
it may safely cast the base request pointer it receives in its callbacks
to v2 in order to make use of the new functionality. libpq will query
the application for a v2 hook first, then v1 to maintain backwards
compatibility, before giving up and using the builtin flow.
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Zsolt Parragi <zsolt.parragi@percona.com>
Discussion: https://postgr.es/m/CAOYmi%2BmrGg%2Bn_X2MOLgeWcj3v_M00gR8uz_D7mM8z%3DdX1JYVbg%40mail.gmail.com
This directory contains the source code distribution of the PostgreSQL
database management system.
PostgreSQL is an advanced object-relational database management system
that supports an extended subset of the SQL standard, including
transactions, foreign keys, subqueries, triggers, user-defined types
and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
Jacob Champion
e982331b52