validateReplicaTarget resolves the source hostname once, but the gRPC
client resolved it again at connect, leaving a DNS-rebinding window for
hostname sources. The copy and tail source dials now run through the
same guardedDialerPolicy the remote-storage path uses, so every resolved
address is re-checked against the replica deny list (private peers
allowed) immediately before the TCP connect. guardedDialerPolicy also
moves to util.OutboundDialContext so the guarded path keeps the -ip.bind
source binding the default gRPC dialer had.
The Rust volume server mirrors this with connect_guarded, a tonic
connector that resolves, re-checks each address, and connects to the
first passing IP; handlers use it whenever the untrusted-endpoint
opt-out is off. A handler-level test now exercises the enabled
validation branches for all three source-taking RPCs.