[mythtv] MySQL Database connection through socket fails for MariaDB 10.6

[Michael T. Dean]

On 04/09/2022 01:55 PM, Roland Ernst wrote:
> Why does a connection from mythtv to the database via socket fail
> if the bind-address is not properly configured in MariaDB?

This was almost definitely due to how you specified your MythTV database 
configuration.

MythTV makes some assumptions, based on what the user-specified database 
configuration says, about how to connect to the database. It "always" 
prefers to use socket/shared-memory connections since they're faster, 
unless the user specifies something that implies they explicitly want to 
use TCP/IP connections.

Specifically, if the database port is 0 (flag saying use MySQL default) 
or 3306 (MySQL default) and the DB host name is 127.0.0.1, it will 
ignore the specified-as-an-IP-address host name and use localhost for 
the DB host name and connect using sockets/shared memory.  Thus, the 
"always" is only true with IPv4.

https://github.com/MythTV/mythtv/blob/master/mythtv/libs/libmythbase/mythdbcon.cpp#L159

It's probably now time to update that conditional to take into account 
the IPv6 equivalents of 127.0.0.1 (::1, 0:0:0:0:0:0:0:1, ...?).  One 
could probably even make an argument for handling 0.0.0.0 (and :: or 
0:0:0:0:0:0:0:0), too, though it seems it's never been an issue so 
far--or at least not enough of one to have caused much discussion.

Mike