SDK 2.0.1 checks the server host name in TWO places: Session.OpenAsync (after
the chain is trusted) and DefaultSessionFactory.CreateChannelAsync, against the
certificate in the GetEndpoints reply and before any security-mode test. opc-plc
sends a certificate on its None endpoint, so `connect -u
opc.tcp://10.100.0.35:50000 --validate-host-name` was refused on an
unauthenticated channel, where a host check proves nothing.
All three call sites now pass checkDomain only when the selected endpoint's
SecurityMode != None: OpcUaEndpointSelection.CheckDomainFor for the driver
(OpenSessionOnEndpointAsync, so the failover sweep too) and the AdminUI browser;
the same expression in Client.Shared ConnectToEndpointAsync (shared by
failover). New live tests: driver None + flag on vs :50000 reads; browser None +
flag on vs the NAT fixture browses; the secure + flag refusals still hold.
Docs: name both check sites; a zone-qualified IPv6 host never matches (FindDomain
compares the zone too), so link-local needs validateServerHostName=false; the
match is loose (first label alone, subject DC= parts count, no wildcards), which
caveats the CA recommendation.
Joseph Doherty
9aff90f884