Register a Hook that checks for a pre-obtained token

[0814celsus]

Until now Postgres does not provide a way to pass a eg. user JSON Web Token as an argument via libpq. If you enable OAuth as a Authentication Mechanism PG always want's to get it's own Token through the provided Module for Duckdb however it would be more feasible to be able to connect with a token in hand, as an alternative to user/password. But PG18 provides the PQsetAuthDataHook() API.
When libpq needs a bearer token during OAUTHBEARER authentication it will call the hook and get's the token from the process memory.

Probably two Sources for the token:

1. Environment variable PGOAUTHTOKEN
2. A DuckDB setting Variable (More Secure)

Maybe it possible to register the hook once during extension initialization, before any PQconnectdb call?

void postgres_extension_oauth_init(void) { prev_hook = PQgetAuthDataHook(); PQsetAuthDataHook(oauth_token_hook); }
Related Discussions pgsql-hackers

Maybe the following can be a starting point of a development.

pg_AuthDataHook.c

[staticlibs]

@0814celsus

Hi, thanks for looking into this! I know what OAuth is, but I am not up to date with its usage in Postgres, so cannot add anything substantial right now. If you see how it can be added to duckdb-postgres - I suggest to covert it to a PR. Extension init is done in LoadInternal.