Ticket 50329 - Possible Security Issue: DOS due to ioblocktimeout not applying to TLS

Ticket 50329 - Possible Security Issue: DOS due to ioblocktimeout not applying to TLS

Bug Description:
	A secure socket is configured in blocking mode. If an event
	is detected on a secure socket a worker, tries to read the request.
	The read can hang indefinitely if there is nothing to read.
	As a consequence ioblocktimeout is not enforced when reading secure socket

Fix Description:
	The fix is specific to secure socket read.
	Before reading it polls the socket for a read. The socket is poll
	(with a 0.1s timeout) until read is possible or sum of poll timeout
	is greater than ioblocktimeout.

https://pagure.io/389-ds-base/issue/50329

Reviewed by: Mark Reynolds

Platforms tested: F28

Flag Day: no

Doc impact: no

Gbp-Pq: Name CVE-2019-3883.patch