DRIVERS-3329: Configurable DNS domain validation for SRV records

[sleepyStick]

Please complete the following before merging:

• Is the relevant DRIVERS ticket in the PR title?

• Update changelog.
• Test changes in at least one language driver.
  Python PR: PYTHON-5814 Configurable DNS domain validation for SRV records mongo-python-driver#2868
• Test these changes against all server versions and topologies (including standalone, replica set, and sharded
  clusters).

[rozza]

It looks good, I have one comment about if an invalid srvAllowedHostsSuffix should throw an error explicitly? (if so should we update the yml?)

Also the yml and json has diverged for srvAllowedHostsSuffix-without_dot_pass - which is probably the lint error.

[rozza]

Just to clarify, if a host is invalid eg: ..example.com should this error or just return an empty list of hosts?

[sleepyStick]

oh good question, my current implementation has it eventually erroring (with a configuration error) when the driver goes to validate the SRV hosts -- i didn't add a new "check valid host" type of function. (though this probably wouldn't be too hard with some regex? if you think it'd be beneficial to add something like this.) My initial thought process was this new parameter is just a user configurable way to denote what the domain should be (as opposed to the previous, now default, logic) -- they should know what they're doing if they're using this param and if they happened to make a typo / silly mistake, the existing "invalid SRV host" error message that occurs when there is an invalid host given the previous logic would still apply.

[rozza]

I think the eventually error part will cover this, so no need for a regex. I can never understand regexes and someone always seems to find a usecase where the regex fails where it shouldn't!