Due to MDEV-15556 and MDEV-15840 recursive CTEs can't be reliably used
with older 10.2 versions. To prevent problems, only use the query that
extracts composite roles with newer versions.
Allocating the session before a DCB guarantees that at no point will a DCB
have a null session. This further clarifies the concept of the session and
also allows the listener reference to be moved there.
Ideally, the session itself would allocate and assign the client DCB but
since the Listener is the only one who does it, it's acceptable for now.
More of the DCB initialization is now done in the DCB constructor. This
makes the creation of new DCBs simpler but it can be even simpler. By
passing the file descriptor that the DCB should use into the constructor
almost all of the initialization would be done inside it.
Also removed the unused path member variable.
The class is still mostly the same as the old C version but it now uses
std::string instead of char pointers. Changed configuration default values
so that the parameters passed to the listener allocation are always valid.
The authentication code did not initialize one of the buffers used to
calculate the password hashes. This resulted in the use of uninitialized
memory when the user provided no password.
If a 10.2.11 or older server without a grant on all mysql tables is found,
the authenticator now falls back to the 10.1 behavior that uses subqueries
instead of CTEs. This is a more user friendly way of working around
MDEV-13453 that causes the problem as all functionality except the support
for composite roles is retained.
If the password field in mysql.user is empty, it is possible that the
actual password is stored in the authentication_string field. Most of the
time this happens due to MDEV-16774 which causes the password to be stored
in the authentication_string field.
Also added a test case that verifies the problem and that it is fixed by
this commit.
Instead of looking at the server version, the actual error message should
be inspected. This guarantees that the correct error message is logged
even with custom builds.
When the 10.2 users query is executed with a MariaDB server older than
10.2.11, the query will fail due to inadequate grants on the 'users' table
generated as a part of the CTE. To work around the issue, a SELECT grant
on the whole mysql database is required. Logging the server where the
query fails also helps resolve the problem by pointing out where the grant
needs to be added.
Added support for composite roles for 10.2 and newer versions. As
recursive CTEs are required to extract the role mappings, composite roles
aren't supported on 10.1.
See script directory for method. The script to run in the top level
MaxScale directory is called maxscale-uncrustify.sh, which uses
another script, list-src, from the same directory (so you need to set
your PATH). The uncrustify version was 0.66.
The maxscale_is_shutting_down function is used to detect when MaxScale
should stop. This fixes a race condition in the code where the workers has
not yet been initialized but a termination signal has been received. It
also replaces the misuse of the service_should_stop variable with a proper
function.
