The hook fires when a flow is removed for any reason (LRU capacity eviction,
tuple-collision displacement, or idle-time expiry). The hook is invoked
exactly once per flow, after the flow table mutex is released, so callbacks
may safely acquire other locks.
We rename the IPMapper interface to Conn25Datapath, and add
ClientFlowCreated/ClientFlowRemoved methods so *Conn25 can keep client-side
address assignments alive while traffic is in flight. Those methods are
currently stubbed for future work.
Connector flows do not currently call these methods.
Updates tailscale/corp#38630
Updates tailscale/corp#43180
Signed-off-by: Michael Ben-Ami <mzb@tailscale.com>
The returned error in the signature is left over from previous
implementations and was only returning nil.
If we know NewFlow will succeed we can fire a create hook (implemented
in a future commit) before NewFlow, which will prevent a remove hook for
a flow from firing before the create hook for the same flow.
Updates tailscale/corp#38630
Signed-off-by: Michael Ben-Ami <mzb@tailscale.com>
Track lastSeen on each cached flow and add a sweeper goroutine
that periodically removes flows idle past the idle timeout.
Introduce tunables for idle timeout, maximum flows removed per sweep (to
limit mutex hold time), and the sweeper interval.
Also cap the previously-unlimited tables: 10k client flows, 100k
connector flows.
Updates tailscale/corp#38630
Signed-off-by: Michael Ben-Ami <mzb@tailscale.com>
When a connector receives a packet from a client on a transit IP that it
can't find a real IP mapping for, it drops the packet. This commit
starts notifying the client of this dropping over TSMP, so the client
can tell the connector to re-establish the transit IP-real IP binding.
Updates tailscale/corp#34256.
Signed-off-by: Naman Sood <mail@nsood.in>
Previously we had two maps keyed on a direction-specific tuple, with
distinct values containing the data (action) for that direction.
Values pointed at each other across maps to ensure they were removed
at the same time in the case of tuple overwrite, but LRU eviction
was per-map. So if LRU was turned on, it was possible for one
direction's data (action) to be evicted and leave the other direction
dangling.
NewFlow replaces the two direction-specific flow constructors, and
lookups return the direction-specific PacketAction directly.
Now the values in each map point to the same element, with data for both
directions in the element. A linked list also points to the elements to
implement LRU. The previous flowtrack.Cache is removed.
The single LRU structure will allow us to implement idle time expiration
by walking the list backward starting with the least recently used flow, and
stopping after a fixed number of flows, or at the first non-expired flow.
We add commented-out unused placeholder fields for tracking the
"last seen" timestamp, and an on-removal hook, to document the intent for
the follow-up expiry work.
Updates tailscale/corp#38630
Signed-off-by: Michael Ben-Ami <mzb@tailscale.com>
Install the previously uninstalled hooks for the filter and tstun
intercepts. Move the DNS manager hook installation into Init() with all
the others. Protect all implementations with a short-circuit if the node
is not configured to use Connectors 2025. The short-circuit pattern
replaces the previous pattern used in managing the DNS manager hook, of
setting it to nil in response to CapMap changes.
Fixestailscale/corp#38716
Signed-off-by: Michael Ben-Ami <mzb@tailscale.com>
Introduce a datapathHandler that implements hooks that will
receive packets from the tstun.Wrapper. This commit does not wire
those up just yet.
Perform DNAT from Magic IP to Transit IP on outbound flows on clients,
and reverse SNAT in the reverse direction.
Perform DNAT from Transit IP to final destination IP on outbound flows
on connectors, and reverse SNAT in the reverse direction.
Introduce FlowTable to cache validated flows by 5-tuple for fast lookups
after the first packet.
Flow expiration is not covered, and is intended as future work before
the feature is officially released.
Fixestailscale/corp#34249Fixestailscale/corp#35995
Co-authored-by: Fran Bull <fran@tailscale.com>
Signed-off-by: Michael Ben-Ami <mzb@tailscale.com>
Michael Ben-Amiandmzbenami
Naman Sood
