tailscale/wgengine/netstack, branch awly/deadcode-pool

wgengine/netstack: absorb all quad-100 traffic locally, never leak to peers

2026-04-24T19:42:16Z

Previously, handleLocalPackets intercepted traffic to the Tailscale service IP (100.100.100.100 / fd7a:115c:a1e0::53) only for an allow-list of ports: TCP 53/80/8080 and UDP 53. Any other port returned filter.Accept, letting the packet fall through to the ACL filter and wireguard-go, which would attempt a peer lookup. No peer owns the quad-100 AllowedIP, so after ~5s pendopen.go would log: open-conn-track: timeout opening ...; no associated peer node This is the common "conntrack error no peer found for 100.100.100.100:853" log spam seen in the wild (e.g. from systemd-resolved or another resolver speculatively trying DoT on quad-100). It also leaks quad-100 packets onto the tailnet. Remove the port allow-list so handleLocalPackets absorbs every quad-100 packet into netstack regardless of IP protocol or port. Traffic never reaches the conntrack / peer-routing layers. With the allow-list gone, acceptTCP needs a corresponding guard: on a quad-100 TCP port we don't serve, execution used to fall through to the isTailscaleIP case (quad-100 is in the tailscale IP range), which rewrote the dial target to 127.0.0.1: and forwardTCP'd the connection to whatever happened to be listening on the host's loopback at that port. Add a hittingServiceIP case that RSTs cleanly instead, placed before the isTailscaleIP fallthrough. TestQuad100UnservedTCPPortDoesNotForward is a new integration test that injects a TCP SYN to 100.100.100.100:853 via handleLocalPackets, stubs forwardDialFunc, and asserts the dialer is not invoked; it catches regressions of the acceptTCP recursion/loopback-redirection case. Fixes #15796 Fixes #19421 Updates #3261 Updates #11305 Signed-off-by: James Tucker

all: fix six tests that failed with -count=2

2026-04-14T01:52:57Z

Avery found a bunch of tests that fail with -count=2. Updates tailscale/corp#40176 (tracks making our CI detect them) Change-Id: Ie3e4398070dd92e4fe0146badddf1254749cca20 Signed-off-by: Brad Fitzpatrick Co-authored-by: Avery Pennarun

wgengine/netstack: fix data race on in-flight connection test globals

2026-04-13T22:24:35Z

The maxInFlightConnectionAttemptsForTest and maxInFlightConnectionAttemptsPerClientForTest globals were plain ints read by background gVisor TCP handler goroutines (via wrapTCPProtocolHandler) and written by tstest.Replace cleanup in TestTCPForwardLimits_PerClient. When a gVisor goroutine outlived the test cleanup window, the race detector caught the unsynchronized access. The race-prone code was introduced in c5abbcd4b4d8 (2024-02-26, "wgengine/netstack: add a per-client limit for in-flight TCP forwards") which added both the plain int globals and the TestTCPForwardLimits_PerClient test that writes them via tstest.Replace. It is not obvious why this has only recently started being detected as a data race; likely some combination of gVisor version bumps, Go toolchain scheduler changes, and additional TCP-injecting subtests (e.g. 03461ea7f, 2026-01-30) increased goroutine churn enough to hit the window. Change both globals to atomic.Int32 and replace tstest.Replace (which does non-atomic *target = old on cleanup) with explicit Store/Cleanup pairs. Fixes #19118 Change-Id: Id26ba6fbfb2e4ade319976db80af8e16c7c8778e Signed-off-by: Brad Fitzpatrick

wgengine/netstack: allow UDP listeners to receive traffic on Service VIP addresses (#18972)

2026-04-08T09:53:50Z

Fixes UDP listeners on VIP Service addresses not receiving inbound traffic. - Modified shouldProcessInbound to check for registered UDP transport endpoints when processing packets to service VIPs - Uses FindTransportEndpoint to determine if a UDP listener exists for the destination VIP/port - Supports both IPv4 and IPv6 The aim was to mirror the existing TCP logic, providing feature parity for UDP-based services on VIP Services. Fixes #18971 Signed-off-by: chaosinthecrd

wgengine/netstack: add TS_NETSTACK_KEEPALIVE_{IDLE,INTERVAL} envknobs

2026-03-17T20:44:11Z

Adds envknobs to override the netstack default TCP keepalive idle time (~2h) and probe interval (75s) for forwarded connections. When a tailnet peer goes away without closing its connections (pod deleted, peer removed from the netmap, silent network partition), the forwardTCP io.Copy goroutines block until keepalive fires: the gvisor-side Read waits on a peer that will never send again, and the backend-side Read waits on a backend that is alive and idle. With the netstack default of 7200s idle + 9×75s probes, dead-peer detection takes a little over two hours. Under high-churn forwarding — many short-lived peers, or peers holding thousands of proxied connections that drop at once — stuck goroutines accumulate faster than they clear. The existing SetKeepAlive(true) at this site enables keepalive without setting the timers; the TODO above it noted "a shorter default might be better" and "might be a useful user-tunable". This makes both timers tunable without changing the defaults: unset preserves the ~2h behavior, which is the right trade-off for battery-powered peers. The two knobs are independent — setting one leaves the other at the netstack default. The options are set before SetKeepAlive(true) so the timer arms with the configured values rather than the defaults — matches the order in ipnlocal/local.go for SSH keepalive. Updates #4522 Signed-off-by: Josef Bacik

wgengine/netstack: don't register subnet/4via6 TCP flows with proxymap

2026-03-14T02:41:30Z

Fixes #18991 Change-Id: I29a609dcd401854026aef4a5ad8d5806c3249ea6 Signed-off-by: Brad Fitzpatrick

wgengine{,/magicsock}: add DERP hooks for filtering+sending packets

2026-03-11T23:37:19Z

Add two small APIs to support out-of-tree projects to exchange custom signaling messages over DERP without requiring disco protocol extensions: - OnDERPRecv callback on magicsock.Options / wgengine.Config: called for every non-disco DERP packet before the peer map lookup, allowing callers to intercept packets from unknown peers that would otherwise be dropped. - SendDERPPacketTo method on magicsock.Conn: sends arbitrary bytes to a node key via a DERP region, creating the connection if needed. Thin wrapper around the existing internal sendAddr. Also allow netstack.Start to accept a nil LocalBackend for use cases that wire up TCP/UDP handlers directly without a full LocalBackend. Updates tailscale/corp#24454 Change-Id: I99a523ef281625b8c0024a963f5f5bf5d8792c17 Signed-off-by: Brad Fitzpatrick

wgengine/netstack: deliver self-addressed packets via loopback

2026-02-27T22:30:41Z

When a tsnet.Server dials its own Tailscale IP, TCP SYN packets are silently dropped. In inject(), outbound packets with dst=self fail the shouldSendToHost check and fall through to WireGuard, which has no peer for the node's own address. Fix this by detecting self-addressed packets in inject() using isLocalIP and delivering them back into gVisor's network stack as inbound packets via a new DeliverLoopback method on linkEndpoint. The outbound packet must be re-serialized into a new PacketBuffer because outbound packets have their headers parsed into separate views, but DeliverNetworkPacket expects raw unparsed data. Updates #18829 Signed-off-by: James Tucker

go.mod: bump gvisor

2026-02-27T02:29:36Z

Updates #8043 Change-Id: Ia229ad4f28f2ff20e0bdecb99ca9e1bd0356ad8e Signed-off-by: Brad Fitzpatrick

wgengine/netstack: add local tailscale service IPs to route and terminate locally (#18461)

2026-01-30T21:46:03Z

* wgengine/netstack: add local tailscale service IPs to route and terminate locally This commit adds the tailscales service IPs served locally to OS routes, and make interception to packets so that the traffic terminates locally without making affects to the HA traffics. Fixes tailscale/corp#34048 Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com> * fix test Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com> * add ready field to avoid accessing lb before netstack starts Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com> * wgengine/netstack: store values from lb to avoid acquiring a lock Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com> * add active services to netstack on starts with stored prefs. Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com> * fix comments Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com> * update comments Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com> --------- Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com>