This preserves the last_ip_and_port field from node lookups through
CreateAuditOrderLimits() and CreateAuditOrderLimit(), so that later
calls to (*Verifier).GetShare() can try to use that IP and port. If a
connection to the given IP and port cannot be made, or the connection
cannot be verified and secured with the target node identity, an
attempt is made to connect to the original node address instead.
A similar change is not necessary to the other Create*OrderLimits
functions, because they already replace node addresses with the cached
IP and port as appropriate. We might want to consider making a similar
change to CreateGetRepairOrderLimits(), though.
The audit situation is unique because the ramifications are especially
powerful when we get the address wrong. Failing a single audit can have
a heavy cost to a storage node. We need to make extra effort in order
to avoid imposing that cost unfairly.
Situation 1: If an audit fails because the repair worker failed to make
a DNS query (which might well be the fault on the satellite side), and
we have last_ip_and_port information available for the target node, it
would be unfair not to try connecting to that last_ip_and_port address.
Situation 2: If a node has changed addresses recently and the operator
correctly changed its DNS entry, but we don't bother querying DNS, it
would be unfair to penalize the node for our failure to connect to it.
So the audit worker must try both last_ip_and_port _and_ the node
address as supplied by the SNO.
We elect here to try last_ip_and_port first, on the grounds that (a) it
is expected to work in the large majority of cases, and (b) there
should not be any security concerns with connecting to an out-or-date
address, and (c) avoiding DNS queries on the satellite side helps
alleviate satellite operational load.
Change-Id: I9bf6c6c79866d879adecac6144a6c346f4f61200
