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ipn/ipnlocal,wgengine/magicsock: add basic counters for cached peer connectivity (#19699)

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Add new clientmetric counters for establishing contact with peers while using
cached network map data. To do this, instrument the magicsock.Conn with a bit
to indicate whether its peer data came from a cached netmap. If so, there are
two conditions we will count as establishing connectivity to a peer:

  - Receipt of a CallMeMaybe from a peer via disco.
  - Establishing a valid endpoint address for a peer.

In vmtest, add Env.ClientMetrics to scrape metrics from the specified node.
Use this to check that counters were updated in caching tests.

Updates https://github.com/tailscale/projects/issues/13
Updates #12639

Change-Id: Ie8cf3244ac8af4f5bcfe4d0d944078da2ba08990
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
This commit is contained in:
M. J. Fromberger
2026-05-12 12:01:05 -07:00
committed by GitHub
parent 120bfcf1cc
commit 9f48567bf1
5 changed files with 155 additions and 20 deletions
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wgengine/magicsock/endpoint.go
+7
View File
@@ -138,6 +138,13 @@ func (de *endpoint) udpRelayEndpointReady(maybeBest addrQuality) {
func (de *endpoint) setBestAddrLocked(v addrQuality) {
if v.epAddr != de.bestAddr.epAddr {
de.probeUDPLifetime.resetCycleEndpointLocked()
// Reaching here, if we are using data from a cached netmap and we are
// upgrading from an invalid (missing) address to a valid one, increment
// the counter for peers established.
if !de.bestAddr.ap.IsValid() && v.ap.IsValid() && de.c.usingCachedNetmap.Load() {
metricCachedPeerContactDirect.Add(1)
}
}
de.bestAddr = v
}
wgengine/magicsock/magicsock.go
+44 -15
View File
@@ -272,6 +272,9 @@ type Conn struct {
// discoAtomic is the current disco private and public keypair for this conn.
discoAtomic discoAtomic
// usingCacheNetmap is whether the latest update to self and peersByID are from a cached network map
usingCachedNetmap atomic.Bool
// ============================================================
// mu guards all following fields; see userspaceEngine lock
// ordering rules against the engine. For derphttp, mu must
@@ -355,18 +358,19 @@ type Conn struct {
// magicsock could do with any complexity reduction it can get.
netInfoLast *tailcfg.NetInfo
derpMap *tailcfg.DERPMap // nil (or zero regions/nodes) means DERP is disabled
self tailcfg.NodeView // from last SetNetworkMap
peersByID map[tailcfg.NodeID]tailcfg.NodeView // current peer set, keyed by NodeID. Maintained by SetNetworkMap/UpsertPeer/RemovePeer. Note: per-field NodeMutation patches received in UpdateNetmapDelta are never applied to these snapshots.
filt *filter.Filter // from last SetFilter
relayClientEnabled bool // whether we can allocate UDP relay endpoints on UDP relay servers or receive CallMeMaybeVia messages from peers
lastFlags debugFlags // at time of last SetNetworkMap
privateKey key.NodePrivate // WireGuard private key for this node
everHadKey bool // whether we ever had a non-zero private key
myDerp int // nearest DERP region ID; 0 means none/unknown
homeless bool // if true, don't try to find & stay conneted to a DERP home (myDerp will stay 0)
derpStarted chan struct{} // closed on first connection to DERP; for tests & cleaner Close
activeDerp map[int]activeDerp // DERP regionID -> connection to a node in that region
derpMap *tailcfg.DERPMap // nil (or zero regions/nodes) means DERP is disabled
self tailcfg.NodeView // from last SetNetworkMap
peersByID map[tailcfg.NodeID]tailcfg.NodeView // current peer set, keyed by NodeID. Maintained by SetNetworkMap/UpsertPeer/RemovePeer. Note: per-field NodeMutation patches received in UpdateNetmapDelta are never applied to these snapshots.
filt *filter.Filter // from last SetFilter
relayClientEnabled bool // whether we can allocate UDP relay endpoints on UDP relay servers or receive CallMeMaybeVia messages from peers
lastFlags debugFlags // at time of last SetNetworkMap
privateKey key.NodePrivate // WireGuard private key for this node
everHadKey bool // whether we ever had a non-zero private key
myDerp int // nearest DERP region ID; 0 means none/unknown
homeless bool // if true, don't try to find & stay conneted to a DERP home (myDerp will stay 0)
derpStarted chan struct{} // closed on first connection to DERP; for tests & cleaner Close
activeDerp map[int]activeDerp // DERP regionID -> connection to a node in that region
prevDerp map[int]*syncs.WaitGroupChan
// derpRoute contains optional alternate routes to use as an
@@ -2334,6 +2338,13 @@ func (c *Conn) handleDiscoMessage(msg []byte, src epAddr, shouldBeRelayHandshake
c.logf("[unexpected] %s from peer via DERP whose netmap discokey != disco source", msgType)
return
}
// Reaching here, if we are using data from a cached network map the
// receipt of a CallMeMaybe from a peer indicates we have a sufficiently
// viable connection to that peer to count it as active while cached.
if c.usingCachedNetmap.Load() {
metricCachedPeerContactDERP.Add(1)
}
if isVia {
c.dlogf("[v1] magicsock: disco: %v<-%v via %v (%v, %v) got call-me-maybe-via, %d endpoints",
c.discoAtomic.Short(), epDisco.short, via.ServerDisco.ShortString(),
@@ -2954,9 +2965,10 @@ func (c *candidatePeerRelay) isValid() bool {
return !c.nodeKey.IsZero() && !c.discoKey.IsZero()
}
// SetNetworkMap updates the network map with the given self node and peers.
// It must be called synchronously from the caller's goroutine to ensure
// magicsock has the current state before subsequent operations proceed.
// SetNetworkMap updates the network map with the given self node and peers
// reported by the control plane (rather than cached). It must be called
// synchronously from the caller's goroutine to ensure magicsock has the
// current state before subsequent operations proceed.
//
// self may be invalid if there's no network map.
//
@@ -2966,6 +2978,18 @@ func (c *candidatePeerRelay) isValid() bool {
// initial netmap and for changes to self or to global state (filter, DERP,
// etc.) that aren't covered by the per-peer methods.
func (c *Conn) SetNetworkMap(self tailcfg.NodeView, peers []tailcfg.NodeView) {
c.setNetworkMapInternal(self, peers, false)
}
// SetNetworkMapCached behaves as SetNetworkMap, but indicates to c that the
// data provided are from a cache rather than the control plane. The same
// constraints otherwise apply.
func (c *Conn) SetNetworkMapCached(self tailcfg.NodeView, peers []tailcfg.NodeView) {
c.setNetworkMapInternal(self, peers, true)
}
// setNetworkMapInternal is the shared implementation of SetNetworkMap and SetNetworkMapCached.
func (c *Conn) setNetworkMapInternal(self tailcfg.NodeView, peers []tailcfg.NodeView, isCached bool) {
peersChanged := c.updateNodes(self, peers)
relayClientEnabled := self.Valid() &&
@@ -2979,6 +3003,7 @@ func (c *Conn) SetNetworkMap(self tailcfg.NodeView, peers []tailcfg.NodeView) {
selfView := c.self
peersSnap := c.peerSnapshotLocked()
isClosed := c.closed
c.usingCachedNetmap.Store(isCached)
c.mu.Unlock() // release c.mu before potentially calling c.updateRelayServersSet which is O(m * n)
if isClosed {
@@ -4198,6 +4223,10 @@ var (
metricTSMPDiscoKeyAdvertisementReceived = clientmetric.NewCounter("magicsock_tsmp_disco_key_advertisement_received")
metricTSMPDiscoKeyAdvertisementApplied = clientmetric.NewCounter("magicsock_tsmp_disco_key_advertisement_applied")
metricTSMPDiscoKeyAdvertisementUnchanged = clientmetric.NewCounter("magicsock_tsmp_disco_key_advertisement_unchanged")
// Counters for peer contacts established using cached network map data.
metricCachedPeerContactDERP = clientmetric.NewCounter("magicsock_cached_peer_contact_derp")
metricCachedPeerContactDirect = clientmetric.NewCounter("magicsock_cached_peer_contact_direct")
)
// newUDPLifetimeCounter returns a new *clientmetric.Metric with the provided