Concurrent registrations of one machine key each saw no existing node and
created their own, duplicating nodes and IPs. Hold a per-machine lock across
the find-then-create section.
Updates #3312
Re-registration mutated the node store before the database write and did not
revert on failure, so a restart could drop the client's current node key.
Snapshot the node and restore it if the write fails.
Updates #3312
The pre-auth-key path wrote the client node key without the collision check
the auth path applies, so a re-registration could claim another node's key
and poison the node-key index. Reject keys bound to a different machine.
Updates #3312
Sentinel ErrNodeKeyInUse (err113); key the visible-peer set by tailcfg.NodeID
to drop an int64->uint64 cast (gosec G115); NewRequestWithContext (noctx); wsl.
applyAuthNodeUpdate rotated the node's NodeKey to the client-supplied value without the 1:1 NodeKey/MachineKey check createAndSaveNewNode (f8f08cf7) and getAndValidateNode enforce. A re-authenticating node could thus rotate its key to a victim's and poison the NodeStore NodeKey index, denying the victim service. Apply the same uniqueness check on the re-auth path.
createAndSaveNewNode trusted the client NodeKey without checking it was already bound to a different machine, so an authenticated party could register a node carrying a victim's public NodeKey, poison the NodeStore NodeKey index, and make the victim's MapRequest resolve to the wrong node (rejected by getAndValidateNode = DoS). Enforce the 1:1 NodeKey/MachineKey binding at registration, as poll time already does.
Drives the persist path for ApprovedRoutes, Tags and Endpoints —
seed a non-empty value, clear to nil, read the column back from disk,
then close the State and reopen one against the same sqlite file to
simulate a server restart. Pins the contract the named IsZero slice
types enforce so future changes to the persist path cannot silently
drop a cleared slice column.
Updates #3110
