GstDtlsConnection throws a warning every minute

Submitted by Andreas Frisch @fraxinas

Link to original bug (#794800)

Description

During a WebRTC session, we've encountered

dtlsconnection gstdtlsconnection.c:747:openssl_poll:GstDtlsConnection@0x7fb63c0aa160 do_handshake encountered BIO error

after 15, 30, 60 seconds and then every minute.

further digging shows that the BIO read gets an EOF and the SSL syscall errno is actually 0 (success) and the error queue is empty.

it may indicate that the peer simply terminated the TCP connection.
maybe something goes wrong with rtcp here, or is this intentional behaviour?