Experimenting with fw event reporting

control.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/cert"
+	"github.com/slackhq/nebula/firewall/events"
 	"github.com/slackhq/nebula/header"
 	"github.com/slackhq/nebula/overlay"
 )
@@ -340,6 +341,36 @@ func (c *Control) Device() overlay.Device {
 	return c.f.inside
 }
 
+// SetFirewallEventReporter installs an event reporter on the current firewall.
+// Passing nil clears any installed reporter. The reporter is carried across
+// firewall rule reloads. Report* methods are invoked while nebula holds
+// internal locks and must be non-blocking; in particular they must not call
+// back into *Control methods that touch the firewall, or deadlock will
+// result.
+//
+// Installation is performed by shallow-copying the current *Firewall,
+// setting the reporter field on the copy, and swapping the pointer under
+// the conntrack lock. Every Firewall the data path sees therefore has an
+// immutable reporter slot, and emit sites can read it without any
+// synchronization of their own.
+func (c *Control) SetFirewallEventReporter(r events.Reporter) {
+	old := c.f.firewall
+	if old == nil {
+		return
+	}
+	old.Conntrack.Lock()
+	defer old.Conntrack.Unlock()
+
+	// Re-read under the lock in case a concurrent reload swapped in a new
+	// Firewall between the unlocked load above and here. Both Firewalls share
+	// the same Conntrack pointer in the normal (non-overflow) reload path,
+	// so the lock we hold is the right one for whichever we see now.
+	current := c.f.firewall
+	fw := *current
+	fw.reporter = r
+	c.f.firewall = &fw
+}
+
 func copyHostInfo(h *HostInfo, preferredRanges []netip.Prefix) ControlHostInfo {
 	chi := ControlHostInfo{
 		VpnAddrs:               make([]netip.Addr, len(h.vpnAddrs)),

firewall.go

@@ -20,6 +20,7 @@ import (
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/firewall"
+	"github.com/slackhq/nebula/firewall/events"
 )
 
 type FirewallInterface interface {
@@ -67,6 +68,14 @@ type Firewall struct {
 	incomingMetrics     firewallMetrics
 	outgoingMetrics     firewallMetrics
 
+	// reporter is the optional embedder-supplied event sink. Immutable for
+	// the lifetime of this Firewall; Control.SetFirewallEventReporter
+	// installs it by shallow-copying the Firewall under the conntrack lock
+	// and swapping the pointer, and reloadFirewall carries it forward.
+	// Read unsynchronized on the data path: the preceding Firewall-pointer
+	// read pins the field's value for the duration of that call.
+	reporter events.Reporter
+
 	l *logrus.Logger
 }
 
@@ -416,23 +425,27 @@ var ErrNoMatchingRule = errors.New("no matching rule in firewall table")
 
 // Drop returns an error if the packet should be dropped, explaining why. It
 // returns nil if the packet should not be dropped.
-func (f *Firewall) Drop(fp firewall.Packet, incoming bool, h *HostInfo, caPool *cert.CAPool, localCache firewall.ConntrackCache) error {
+func (f *Firewall) Drop(fp firewall.Packet, ctx firewall.PacketContext, incoming bool, h *HostInfo, caPool *cert.CAPool, localCache firewall.ConntrackCache) error {
 	// Check if we spoke to this tuple, if we did then allow this packet
 	if f.inConns(fp, h, caPool, localCache) {
 		return nil
 	}
 
+	peerCert := h.ConnectionState.peerCert
+
 	// Make sure remote address matches nebula certificate, and determine how to treat it
 	if h.networks == nil {
 		// Simple case: Certificate has one address and no unsafe networks
 		if h.vpnAddrs[0] != fp.RemoteAddr {
 			f.metrics(incoming).droppedRemoteAddr.Inc(1)
+			f.reportDrop(incoming, events.DropInvalidRemoteIP, fp, ctx, peerCert)
 			return ErrInvalidRemoteIP
 		}
 	} else {
 		nwType, ok := h.networks.Lookup(fp.RemoteAddr)
 		if !ok {
 			f.metrics(incoming).droppedRemoteAddr.Inc(1)
+			f.reportDrop(incoming, events.DropInvalidRemoteIP, fp, ctx, peerCert)
 			return ErrInvalidRemoteIP
 		}
 		switch nwType {
@@ -440,11 +453,13 @@ func (f *Firewall) Drop(fp firewall.Packet, incoming bool, h *HostInfo, caPool *
 			break // nothing special
 		case NetworkTypeVPNPeer:
 			f.metrics(incoming).droppedRemoteAddr.Inc(1)
+			f.reportDrop(incoming, events.DropPeerRejected, fp, ctx, peerCert)
 			return ErrPeerRejected // reject for now, one day this may have different FW rules
 		case NetworkTypeUnsafe:
 			break // nothing special, one day this may have different FW rules
 		default:
 			f.metrics(incoming).droppedRemoteAddr.Inc(1)
+			f.reportDrop(incoming, events.DropUnknownNetwork, fp, ctx, peerCert)
 			return ErrUnknownNetworkType //should never happen
 		}
 	}
@@ -452,6 +467,7 @@ func (f *Firewall) Drop(fp firewall.Packet, incoming bool, h *HostInfo, caPool *
 	// Make sure we are supposed to be handling this local ip address
 	if !f.routableNetworks.Contains(fp.LocalAddr) {
 		f.metrics(incoming).droppedLocalAddr.Inc(1)
+		f.reportDrop(incoming, events.DropInvalidLocalIP, fp, ctx, peerCert)
 		return ErrInvalidLocalIP
 	}
 
@@ -461,13 +477,14 @@ func (f *Firewall) Drop(fp firewall.Packet, incoming bool, h *HostInfo, caPool *
 	}
 
 	// We now know which firewall table to check against
-	if !table.match(fp, incoming, h.ConnectionState.peerCert, caPool) {
+	if !table.match(fp, incoming, peerCert, caPool) {
 		f.metrics(incoming).droppedNoRule.Inc(1)
+		f.reportDrop(incoming, events.DropNoMatchingRule, fp, ctx, peerCert)
 		return ErrNoMatchingRule
 	}
 
 	// We always want to conntrack since it is a faster operation
-	f.addConn(fp, incoming)
+	f.addConn(fp, ctx, incoming, peerCert)
 
 	return nil
 }
@@ -486,6 +503,59 @@ func (f *Firewall) Destroy() {
 	//TODO: clean references if/when needed
 }
 
+func (f *Firewall) reportDrop(incoming bool, reason events.DropReason, fp firewall.Packet, ctx firewall.PacketContext, peerCert *cert.CachedCertificate) {
+	r := f.reporter
+	if r == nil {
+		return
+	}
+	r.ReportDrop(events.DropEvent{
+		Incoming:     incoming,
+		Reason:       reason,
+		Packet:       fp,
+		Context:      ctx,
+		PeerCert:     peerCert,
+		RulesVersion: f.rulesVersion,
+	})
+}
+
+func (f *Firewall) reportFlowCreate(incoming bool, fp firewall.Packet, ctx firewall.PacketContext, peerCert *cert.CachedCertificate) {
+	r := f.reporter
+	if r == nil {
+		return
+	}
+	r.ReportFlowCreate(events.FlowCreateEvent{
+		Incoming:     incoming,
+		Packet:       fp,
+		Context:      ctx,
+		PeerCert:     peerCert,
+		RulesVersion: f.rulesVersion,
+	})
+}
+
+func (f *Firewall) reportFlowEvict(incoming bool, fp firewall.Packet, rulesVersion uint16, expired bool) {
+	r := f.reporter
+	if r == nil {
+		return
+	}
+	r.ReportFlowEvict(events.FlowEvictEvent{
+		Incoming:     incoming,
+		Packet:       fp,
+		RulesVersion: rulesVersion,
+		Expired:      expired,
+	})
+}
+
+func (f *Firewall) reportRulesReload(oldVersion, newVersion uint16) {
+	r := f.reporter
+	if r == nil {
+		return
+	}
+	r.ReportRulesReload(events.RulesReloadEvent{
+		OldVersion: oldVersion,
+		NewVersion: newVersion,
+	})
+}
+
 func (f *Firewall) EmitStats() {
 	conntrack := f.Conntrack
 	conntrack.Lock()
@@ -536,7 +606,9 @@ func (f *Firewall) inConns(fp firewall.Packet, h *HostInfo, caPool *cert.CAPool,
 					WithField("oldRulesVersion", c.rulesVersion).
 					Debugln("dropping old conntrack entry, does not match new ruleset")
 			}
+			oldRulesVersion := c.rulesVersion
 			delete(conntrack.Conns, fp)
+			f.reportFlowEvict(c.incoming, fp, oldRulesVersion, false)
 			conntrack.Unlock()
 			return false
 		}
@@ -571,7 +643,7 @@ func (f *Firewall) inConns(fp firewall.Packet, h *HostInfo, caPool *cert.CAPool,
 	return true
 }
 
-func (f *Firewall) addConn(fp firewall.Packet, incoming bool) {
+func (f *Firewall) addConn(fp firewall.Packet, ctx firewall.PacketContext, incoming bool, peerCert *cert.CachedCertificate) {
 	var timeout time.Duration
 	c := &conn{}
 
@@ -586,7 +658,8 @@ func (f *Firewall) addConn(fp firewall.Packet, incoming bool) {
 
 	conntrack := f.Conntrack
 	conntrack.Lock()
-	if _, ok := conntrack.Conns[fp]; !ok {
+	_, existing := conntrack.Conns[fp]
+	if !existing {
 		conntrack.TimerWheel.Advance(time.Now())
 		conntrack.TimerWheel.Add(fp, timeout)
 	}
@@ -597,6 +670,13 @@ func (f *Firewall) addConn(fp firewall.Packet, incoming bool) {
 	c.rulesVersion = f.rulesVersion
 	c.Expires = time.Now().Add(timeout)
 	conntrack.Conns[fp] = c
+
+	// Report only when this represents a genuinely new flow. Fires under the
+	// conntrack lock so FlowCreate/FlowEvict events stay ordered relative to
+	// RulesReloadEvent, which also fires under this lock.
+	if !existing {
+		f.reportFlowCreate(incoming, fp, ctx, peerCert)
+	}
 	conntrack.Unlock()
 }
 
@@ -620,7 +700,10 @@ func (f *Firewall) evict(p firewall.Packet) {
 	}
 
 	// This conn is done
+	rulesVersion := t.rulesVersion
+	incoming := t.incoming
 	delete(conntrack.Conns, p)
+	f.reportFlowEvict(incoming, p, rulesVersion, true)
 }
 
 func (ft *FirewallTable) match(p firewall.Packet, incoming bool, c *cert.CachedCertificate, caPool *cert.CAPool) bool {

firewall/events/events.go

@@ -0,0 +1,102 @@
+// Package events defines the opt-in firewall event reporting interface.
+//
+// Nebula emits raw packet-level events (drops, flow creations, flow evictions,
+// rule reloads) and does no aggregation, counting, batching, rule-description,
+// transport, or timestamping. Embedders correlate events back to yaml rules
+// out of band and capture whatever clock they need themselves. All Report*
+// methods are invoked while nebula holds internal locks and must be
+// non-blocking.
+//
+// Events are passed to Report* methods by value. Implementations must not
+// take the address of a received event: doing so forces Go's escape
+// analysis to move the event to the heap and costs one allocation per call.
+// To forward an event, either copy its fields into the reporter's own
+// pooled record or send it through a value-typed channel (chan DropEvent,
+// not chan *DropEvent).
+package events
+
+import (
+	"github.com/slackhq/nebula/cert"
+	"github.com/slackhq/nebula/firewall"
+)
+
+type DropReason uint8
+
+const (
+	DropInvalidLocalIP DropReason = iota
+	DropInvalidRemoteIP
+	DropPeerRejected
+	DropUnknownNetwork
+	DropNoMatchingRule
+)
+
+func (r DropReason) String() string {
+	switch r {
+	case DropInvalidLocalIP:
+		return "invalid_local_ip"
+	case DropInvalidRemoteIP:
+		return "invalid_remote_ip"
+	case DropPeerRejected:
+		return "peer_rejected"
+	case DropUnknownNetwork:
+		return "unknown_network"
+	case DropNoMatchingRule:
+		return "no_matching_rule"
+	default:
+		return "unknown"
+	}
+}
+
+// DropEvent is emitted for every packet that fails the firewall check. Drops
+// are not aggregated; every drop produces one event.
+type DropEvent struct {
+	Incoming     bool
+	Reason       DropReason
+	Packet       firewall.Packet
+	Context      firewall.PacketContext
+	PeerCert     *cert.CachedCertificate
+	RulesVersion uint16
+}
+
+// FlowCreateEvent is emitted when a packet is allowed and a new conntrack
+// entry is created. Subsequent packets in the same flow do not re-emit.
+type FlowCreateEvent struct {
+	Incoming     bool
+	Packet       firewall.Packet
+	Context      firewall.PacketContext
+	PeerCert     *cert.CachedCertificate
+	RulesVersion uint16
+}
+
+// FlowEvictEvent is emitted when a conntrack entry is removed. Context is
+// not carried: timer-wheel eviction has no packet in hand, and reload
+// revalidation evicts the OLD flow rather than the triggering packet.
+// RulesVersion is the version under which the flow was originally allowed,
+// which may differ from the current firewall version.
+type FlowEvictEvent struct {
+	Incoming     bool
+	Packet       firewall.Packet
+	RulesVersion uint16
+	// Expired is true when eviction was due to conntrack timeout; false when
+	// the entry was removed because it failed re-validation after a reload.
+	Expired bool
+}
+
+// RulesReloadEvent is emitted once after each successful firewall reload.
+// Reporters that bucket state by RulesVersion should close the old bucket
+// and open a new one on receipt.
+type RulesReloadEvent struct {
+	OldVersion uint16
+	NewVersion uint16
+}
+
+// Reporter is the embedder-supplied sink for firewall events. Implementations
+// that want a timestamp should call time.Now() themselves at the top of the
+// method; nebula does not provide one. See the package doc for the
+// do-not-take-address rule.
+type Reporter interface {
+	ReportDrop(DropEvent)
+	ReportFlowCreate(FlowCreateEvent)
+	ReportFlowEvict(FlowEvictEvent)
+	ReportRulesReload(RulesReloadEvent)
+}

firewall/packet.go

@@ -31,6 +31,27 @@ type Packet struct {
 	Fragment   bool
 }
 
+// PacketContext carries additional parsed details about a packet that are
+// useful for event reporting but deliberately kept out of Packet so Packet
+// can keep being used as a conntrack map key. Populated alongside Packet by
+// newPacket.
+//
+// Fields are interpreted based on Packet.Protocol:
+//   - ProtoTCP: TCPFlags is meaningful; ICMPType / ICMPCode are zero
+//   - ProtoICMP, ProtoICMPv6: ICMPType / ICMPCode are meaningful; TCPFlags is zero
+//   - ProtoUDP and others: only Length is meaningful
+type PacketContext struct {
+	// Length is the total IP packet length in bytes, including headers.
+	Length uint16
+	// TCPFlags is the flag byte from the TCP header (bits for FIN, SYN, RST,
+	// PSH, ACK, URG, ECE, CWR).
+	TCPFlags uint8
+	// ICMPType is the type field of the ICMP / ICMPv6 header.
+	ICMPType uint8
+	// ICMPCode is the code field of the ICMP / ICMPv6 header.
+	ICMPCode uint8
+}
+
 func (fp *Packet) Copy() *Packet {
 	return &Packet{
 		LocalAddr:  fp.LocalAddr,

firewall_events_test.go

@@ -0,0 +1,731 @@
+package nebula
+
+import (
+	"net"
+	"net/netip"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/gaissmai/bart"
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
+	"github.com/slackhq/nebula/cert"
+	"github.com/slackhq/nebula/firewall"
+	"github.com/slackhq/nebula/firewall/events"
+	"github.com/slackhq/nebula/test"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// recordingReporter captures every event fired against it. Its methods take
+// the conntrack lock implicitly (via the firewall code path that invokes
+// them), so we synchronize accumulator mutations with a small mutex to keep
+// the race detector happy across goroutines in case a test introduces any.
+type recordingReporter struct {
+	mu      sync.Mutex
+	drops   []recordedDrop
+	creates []recordedCreate
+	evicts  []recordedEvict
+	reloads []recordedReload
+}
+
+type recordedDrop struct {
+	incoming     bool
+	reason       events.DropReason
+	remote       netip.Addr
+	local        netip.Addr
+	peerName     string
+	rulesVersion uint16
+	ctx          firewall.PacketContext
+}
+
+type recordedCreate struct {
+	incoming     bool
+	remote       netip.Addr
+	local        netip.Addr
+	peerName     string
+	rulesVersion uint16
+	ctx          firewall.PacketContext
+}
+
+type recordedEvict struct {
+	incoming     bool
+	remote       netip.Addr
+	local        netip.Addr
+	rulesVersion uint16
+	expired      bool
+}
+
+type recordedReload struct {
+	oldVersion uint16
+	newVersion uint16
+}
+
+func (r *recordingReporter) ReportDrop(e events.DropEvent) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	name := ""
+	if e.PeerCert != nil && e.PeerCert.Certificate != nil {
+		name = e.PeerCert.Certificate.Name()
+	}
+	r.drops = append(r.drops, recordedDrop{
+		incoming:     e.Incoming,
+		reason:       e.Reason,
+		remote:       e.Packet.RemoteAddr,
+		local:        e.Packet.LocalAddr,
+		peerName:     name,
+		rulesVersion: e.RulesVersion,
+		ctx:          e.Context,
+	})
+}
+
+func (r *recordingReporter) ReportFlowCreate(e events.FlowCreateEvent) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	name := ""
+	if e.PeerCert != nil && e.PeerCert.Certificate != nil {
+		name = e.PeerCert.Certificate.Name()
+	}
+	r.creates = append(r.creates, recordedCreate{
+		incoming:     e.Incoming,
+		remote:       e.Packet.RemoteAddr,
+		local:        e.Packet.LocalAddr,
+		peerName:     name,
+		rulesVersion: e.RulesVersion,
+		ctx:          e.Context,
+	})
+}
+
+func (r *recordingReporter) ReportFlowEvict(e events.FlowEvictEvent) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.evicts = append(r.evicts, recordedEvict{
+		incoming:     e.Incoming,
+		remote:       e.Packet.RemoteAddr,
+		local:        e.Packet.LocalAddr,
+		rulesVersion: e.RulesVersion,
+		expired:      e.Expired,
+	})
+}
+
+func (r *recordingReporter) ReportRulesReload(e events.RulesReloadEvent) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.reloads = append(r.reloads, recordedReload{
+		oldVersion: e.OldVersion,
+		newVersion: e.NewVersion,
+	})
+}
+
+// eventFixture builds a Firewall wired to a Control plus a packet/hostinfo
+// pair that a test can reuse. By default the ruleset allows the packet;
+// callers mutate fw / p / h as needed before invoking Drop.
+type eventFixture struct {
+	ctl *Control
+	fw  *Firewall
+	p   firewall.Packet
+	h   *HostInfo
+	cp  *cert.CAPool
+}
+
+func newEventFixture(t *testing.T) *eventFixture {
+	t.Helper()
+	l := test.NewLogger()
+
+	// myVpnNetworksTable covers our single peer address so buildNetworks takes
+	// the "simple case" path (h.networks stays nil); tests that want a populated
+	// BART table overwrite h.networks directly.
+	vpnNetworks := new(bart.Lite)
+	vpnNetworks.Insert(netip.MustParsePrefix("1.2.3.0/24"))
+
+	// Use the same cert for "peer" and "local" endpoints, matching the
+	// TestFirewall_Drop fixture style: LocalAddr == RemoteAddr == peer vpn addr.
+	c := &dummyCert{
+		name:     "host1",
+		networks: []netip.Prefix{netip.MustParsePrefix("1.2.3.4/24")},
+		groups:   []string{"default-group"},
+		issuer:   "signer-shasum",
+	}
+	h := &HostInfo{
+		ConnectionState: &ConnectionState{
+			peerCert: &cert.CachedCertificate{
+				Certificate:    c,
+				InvertedGroups: map[string]struct{}{"default-group": {}},
+			},
+		},
+		vpnAddrs: []netip.Addr{netip.MustParseAddr("1.2.3.4")},
+	}
+	h.buildNetworks(vpnNetworks, c)
+
+	fw := NewFirewall(l, time.Minute, time.Minute, time.Minute, c)
+	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"any"}, "", "", "", "", ""))
+	require.NoError(t, fw.AddRule(false, firewall.ProtoAny, 0, 0, []string{"any"}, "", "", "", "", ""))
+
+	ctl := &Control{
+		f: &Interface{firewall: fw},
+		l: l,
+	}
+
+	return &eventFixture{
+		ctl: ctl,
+		fw:  fw,
+		p: firewall.Packet{
+			LocalAddr:  netip.MustParseAddr("1.2.3.4"),
+			RemoteAddr: netip.MustParseAddr("1.2.3.4"),
+			LocalPort:  10,
+			RemotePort: 90,
+			Protocol:   firewall.ProtoUDP,
+		},
+		h:  h,
+		cp: cert.NewCAPool(),
+	}
+}
+
+// firewall() returns the currently-installed firewall. Needed because
+// SetFirewallEventReporter replaces it via shallow-copy swap.
+func (f *eventFixture) firewall() *Firewall {
+	return f.ctl.f.firewall
+}
+
+func TestEvents_ReportDrop_InvalidRemoteIP(t *testing.T) {
+	f := newEventFixture(t)
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	// Packet to an address not in the cert's networks.
+	f.p.RemoteAddr = netip.MustParseAddr("9.9.9.9")
+	assert.Equal(t, ErrInvalidRemoteIP, f.firewall().Drop(f.p, firewall.PacketContext{}, false, f.h, f.cp, nil))
+
+	require.Len(t, r.drops, 1)
+	assert.Equal(t, events.DropInvalidRemoteIP, r.drops[0].reason)
+	assert.False(t, r.drops[0].incoming)
+	assert.Equal(t, "host1", r.drops[0].peerName)
+	assert.Empty(t, r.creates)
+	assert.Empty(t, r.evicts)
+}
+
+func TestEvents_ReportDrop_InvalidLocalIP(t *testing.T) {
+	f := newEventFixture(t)
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	// LocalAddr outside our routable networks.
+	f.p.LocalAddr = netip.MustParseAddr("9.9.9.9")
+	assert.Equal(t, ErrInvalidLocalIP, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+
+	require.Len(t, r.drops, 1)
+	assert.Equal(t, events.DropInvalidLocalIP, r.drops[0].reason)
+	assert.True(t, r.drops[0].incoming)
+}
+
+func TestEvents_ReportDrop_NoMatchingRule(t *testing.T) {
+	f := newEventFixture(t)
+	// Reset to a firewall with no matching rule.
+	l := test.NewLogger()
+	fw := NewFirewall(l, time.Minute, time.Minute, time.Minute, f.h.ConnectionState.peerCert.Certificate)
+	// Rule that won't match (group not in peer's groups).
+	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", ""))
+	require.NoError(t, fw.AddRule(false, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", ""))
+	f.ctl.f.firewall = fw
+
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	assert.Equal(t, ErrNoMatchingRule, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	require.Len(t, r.drops, 1)
+	assert.Equal(t, events.DropNoMatchingRule, r.drops[0].reason)
+}
+
+func TestEvents_ReportDrop_PeerRejected(t *testing.T) {
+	f := newEventFixture(t)
+	// Re-classify the remote as VPNPeer so it triggers DropPeerRejected.
+	f.h.networks = new(bart.Table[NetworkType])
+	f.h.networks.Insert(netip.MustParsePrefix("1.2.3.0/24"), NetworkTypeVPNPeer)
+
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	assert.Equal(t, ErrPeerRejected, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	require.Len(t, r.drops, 1)
+	assert.Equal(t, events.DropPeerRejected, r.drops[0].reason)
+}
+
+func TestEvents_ReportDrop_UnknownNetwork(t *testing.T) {
+	f := newEventFixture(t)
+	// Insert an unrecognized NetworkType value to hit the default branch.
+	f.h.networks = new(bart.Table[NetworkType])
+	f.h.networks.Insert(netip.MustParsePrefix("1.2.3.0/24"), NetworkTypeUnknown)
+
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	assert.Equal(t, ErrUnknownNetworkType, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	require.Len(t, r.drops, 1)
+	assert.Equal(t, events.DropUnknownNetwork, r.drops[0].reason)
+}
+
+func TestEvents_ReportFlowCreate_OnceOnly(t *testing.T) {
+	f := newEventFixture(t)
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	// First allowed packet creates the conntrack entry.
+	require.NoError(t, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	// Second matching packet on the same tuple is short-circuited by conntrack
+	// and must not fire another FlowCreate.
+	require.NoError(t, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+
+	require.Len(t, r.creates, 1)
+	assert.True(t, r.creates[0].incoming)
+	assert.Equal(t, f.p.RemoteAddr, r.creates[0].remote)
+	assert.Empty(t, r.drops)
+}
+
+func TestEvents_ReportFlowEvict_OnReloadPurge(t *testing.T) {
+	f := newEventFixture(t)
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	// Create a flow under the current rules.
+	require.NoError(t, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	require.Len(t, r.creates, 1)
+
+	// Simulate a reload that produces rules the existing flow no longer
+	// matches. Bump rulesVersion and replace InRules with an empty table so
+	// revalidation fails.
+	fw := f.firewall()
+	fw.Conntrack.Lock()
+	fw.rulesVersion++
+	fw.InRules = newFirewallTable()
+	fw.Conntrack.Unlock()
+
+	// Next packet triggers re-validation, which fails and evicts the entry.
+	err := fw.Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil)
+	assert.Equal(t, ErrNoMatchingRule, err)
+
+	require.Len(t, r.evicts, 1)
+	assert.False(t, r.evicts[0].expired, "evict from reload purge is not expiration")
+	assert.True(t, r.evicts[0].incoming)
+}
+
+func TestEvents_ReportFlowEvict_OnTimeout(t *testing.T) {
+	f := newEventFixture(t)
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	require.NoError(t, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	require.Len(t, r.creates, 1)
+
+	// Force expiration by rewinding the entry's deadline.
+	fw := f.firewall()
+	fw.Conntrack.Lock()
+	c := fw.Conntrack.Conns[f.p]
+	require.NotNil(t, c)
+	c.Expires = time.Now().Add(-time.Hour)
+	fw.evict(f.p)
+	fw.Conntrack.Unlock()
+
+	require.Len(t, r.evicts, 1)
+	assert.True(t, r.evicts[0].expired)
+}
+
+func TestEvents_SetNil_Clears(t *testing.T) {
+	f := newEventFixture(t)
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+	require.NoError(t, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	require.Len(t, r.creates, 1)
+
+	f.ctl.SetFirewallEventReporter(nil)
+	resetConntrack(f.firewall())
+	require.NoError(t, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	// No second create should be recorded.
+	assert.Len(t, r.creates, 1)
+}
+
+func TestEvents_ReporterSurvivesSwap(t *testing.T) {
+	f := newEventFixture(t)
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	// Simulate a reload by swapping in a fresh Firewall that carries the
+	// reporter forward. Mirrors what reloadFirewall does with the shared
+	// conntrack pointer.
+	l := test.NewLogger()
+	oldFw := f.firewall()
+	newFw := NewFirewall(l, time.Minute, time.Minute, time.Minute, f.h.ConnectionState.peerCert.Certificate)
+	require.NoError(t, newFw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"any"}, "", "", "", "", ""))
+	require.NoError(t, newFw.AddRule(false, firewall.ProtoAny, 0, 0, []string{"any"}, "", "", "", "", ""))
+	newFw.Conntrack = oldFw.Conntrack
+	newFw.rulesVersion = oldFw.rulesVersion + 1
+	newFw.reporter = oldFw.reporter
+	f.ctl.f.firewall = newFw
+	newFw.reportRulesReload(oldFw.rulesVersion, newFw.rulesVersion)
+
+	require.Len(t, r.reloads, 1)
+	assert.Equal(t, oldFw.rulesVersion, r.reloads[0].oldVersion)
+	assert.Equal(t, newFw.rulesVersion, r.reloads[0].newVersion)
+
+	// Events on the new firewall should still reach the same reporter.
+	require.NoError(t, newFw.Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+	require.Len(t, r.creates, 1)
+	assert.Equal(t, newFw.rulesVersion, r.creates[0].rulesVersion)
+}
+
+func TestEvents_InstallDoesNotMutateOldFirewall(t *testing.T) {
+	f := newEventFixture(t)
+	before := f.firewall()
+
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	after := f.firewall()
+	assert.NotSame(t, before, after, "SetFirewallEventReporter must replace the Firewall pointer")
+	assert.Nil(t, before.reporter, "the pre-install Firewall must remain untouched")
+	assert.NotNil(t, after.reporter)
+}
+
+// --- PacketContext parse tests --------------------------------------------
+
+func mustSerialize(t *testing.T, lrs ...gopacket.SerializableLayer) []byte {
+	t.Helper()
+	buf := gopacket.NewSerializeBuffer()
+	opt := gopacket.SerializeOptions{ComputeChecksums: false, FixLengths: true}
+	require.NoError(t, gopacket.SerializeLayers(buf, opt, lrs...))
+	return buf.Bytes()
+}
+
+func TestPacketContext_IPv4_TCPFlags(t *testing.T) {
+	ip := &layers.IPv4{
+		Version: 4, TTL: 64, Protocol: layers.IPProtocolTCP,
+		SrcIP: net.IPv4(10, 0, 0, 1), DstIP: net.IPv4(10, 0, 0, 2),
+	}
+	tcp := &layers.TCP{SrcPort: 1234, DstPort: 80, SYN: true, ACK: true}
+	require.NoError(t, tcp.SetNetworkLayerForChecksum(ip))
+	data := mustSerialize(t, ip, tcp, gopacket.Payload([]byte("hello")))
+
+	var fp firewall.Packet
+	var ctx firewall.PacketContext
+	require.NoError(t, newPacket(data, true, &fp, &ctx))
+
+	assert.Equal(t, uint8(firewall.ProtoTCP), fp.Protocol)
+	// SYN (0x02) + ACK (0x10) = 0x12
+	assert.Equal(t, uint8(0x12), ctx.TCPFlags)
+	assert.Equal(t, uint16(len(data)), ctx.Length)
+	assert.Equal(t, uint8(0), ctx.ICMPType)
+	assert.Equal(t, uint8(0), ctx.ICMPCode)
+}
+
+func TestPacketContext_IPv4_ICMPTypeCode(t *testing.T) {
+	ip := &layers.IPv4{
+		Version: 4, TTL: 64, Protocol: layers.IPProtocolICMPv4,
+		SrcIP: net.IPv4(10, 0, 0, 1), DstIP: net.IPv4(10, 0, 0, 2),
+	}
+	// Destination Unreachable, code 3 (port unreachable)
+	icmp := &layers.ICMPv4{
+		TypeCode: layers.CreateICMPv4TypeCode(layers.ICMPv4TypeDestinationUnreachable, layers.ICMPv4CodePort),
+	}
+	data := mustSerialize(t, ip, icmp, gopacket.Payload([]byte{0, 0, 0, 0}))
+
+	var fp firewall.Packet
+	var ctx firewall.PacketContext
+	require.NoError(t, newPacket(data, true, &fp, &ctx))
+
+	assert.Equal(t, uint8(firewall.ProtoICMP), fp.Protocol)
+	assert.Equal(t, uint8(layers.ICMPv4TypeDestinationUnreachable), ctx.ICMPType)
+	assert.Equal(t, uint8(layers.ICMPv4CodePort), ctx.ICMPCode)
+	assert.Equal(t, uint16(len(data)), ctx.Length)
+	assert.Equal(t, uint8(0), ctx.TCPFlags)
+}
+
+func TestPacketContext_IPv4_UDPLengthOnly(t *testing.T) {
+	ip := &layers.IPv4{
+		Version: 4, TTL: 64, Protocol: layers.IPProtocolUDP,
+		SrcIP: net.IPv4(10, 0, 0, 1), DstIP: net.IPv4(10, 0, 0, 2),
+	}
+	udp := &layers.UDP{SrcPort: 1234, DstPort: 53}
+	require.NoError(t, udp.SetNetworkLayerForChecksum(ip))
+	data := mustSerialize(t, ip, udp, gopacket.Payload([]byte("query")))
+
+	var fp firewall.Packet
+	var ctx firewall.PacketContext
+	require.NoError(t, newPacket(data, true, &fp, &ctx))
+
+	assert.Equal(t, uint8(firewall.ProtoUDP), fp.Protocol)
+	assert.Equal(t, uint16(len(data)), ctx.Length)
+	assert.Zero(t, ctx.TCPFlags)
+	assert.Zero(t, ctx.ICMPType)
+	assert.Zero(t, ctx.ICMPCode)
+}
+
+func TestPacketContext_IPv6_TCPFlags(t *testing.T) {
+	ip := &layers.IPv6{
+		Version: 6, HopLimit: 64, NextHeader: layers.IPProtocolTCP,
+		SrcIP: net.ParseIP("fd00::1"), DstIP: net.ParseIP("fd00::2"),
+	}
+	tcp := &layers.TCP{SrcPort: 1234, DstPort: 443, FIN: true, ACK: true}
+	require.NoError(t, tcp.SetNetworkLayerForChecksum(ip))
+	data := mustSerialize(t, ip, tcp, gopacket.Payload([]byte("bye")))
+
+	var fp firewall.Packet
+	var ctx firewall.PacketContext
+	require.NoError(t, newPacket(data, true, &fp, &ctx))
+
+	assert.Equal(t, uint8(firewall.ProtoTCP), fp.Protocol)
+	// FIN (0x01) + ACK (0x10) = 0x11
+	assert.Equal(t, uint8(0x11), ctx.TCPFlags)
+	assert.Equal(t, uint16(len(data)), ctx.Length)
+}
+
+func TestPacketContext_IPv6_ICMPv6TypeCode(t *testing.T) {
+	ip := &layers.IPv6{
+		Version: 6, HopLimit: 64, NextHeader: layers.IPProtocolICMPv6,
+		SrcIP: net.ParseIP("fd00::1"), DstIP: net.ParseIP("fd00::2"),
+	}
+	icmp := &layers.ICMPv6{
+		TypeCode: layers.CreateICMPv6TypeCode(layers.ICMPv6TypeDestinationUnreachable, layers.ICMPv6CodePortUnreachable),
+	}
+	require.NoError(t, icmp.SetNetworkLayerForChecksum(ip))
+	data := mustSerialize(t, ip, icmp, gopacket.Payload([]byte{0, 0, 0, 0, 0, 0, 0, 0}))
+
+	var fp firewall.Packet
+	var ctx firewall.PacketContext
+	require.NoError(t, newPacket(data, true, &fp, &ctx))
+
+	assert.Equal(t, uint8(firewall.ProtoICMPv6), fp.Protocol)
+	assert.Equal(t, uint8(layers.ICMPv6TypeDestinationUnreachable), ctx.ICMPType)
+	assert.Equal(t, uint8(layers.ICMPv6CodePortUnreachable), ctx.ICMPCode)
+	assert.Equal(t, uint16(len(data)), ctx.Length)
+}
+
+// TestPacketContext_NilOK confirms a nil context pointer is accepted by
+// newPacket (the hot path may elect not to pass one).
+func TestPacketContext_NilOK(t *testing.T) {
+	ip := &layers.IPv4{
+		Version: 4, TTL: 64, Protocol: layers.IPProtocolUDP,
+		SrcIP: net.IPv4(10, 0, 0, 1), DstIP: net.IPv4(10, 0, 0, 2),
+	}
+	udp := &layers.UDP{SrcPort: 1, DstPort: 2}
+	require.NoError(t, udp.SetNetworkLayerForChecksum(ip))
+	data := mustSerialize(t, ip, udp)
+
+	var fp firewall.Packet
+	require.NoError(t, newPacket(data, true, &fp, nil))
+}
+
+// TestPacketContext_FlowCreateCarriesContext exercises the full Drop -> addConn
+// -> ReportFlowCreate path with a realistic TCP packet and confirms the
+// context makes it into the reporter.
+func TestPacketContext_FlowCreateCarriesContext(t *testing.T) {
+	f := newEventFixture(t)
+	r := &recordingReporter{}
+	f.ctl.SetFirewallEventReporter(r)
+
+	// Hand-construct a matching TCP packet.
+	ctx := firewall.PacketContext{Length: 1500, TCPFlags: 0x12}
+	p := f.p
+	p.Protocol = firewall.ProtoTCP
+	require.NoError(t, f.firewall().Drop(p, ctx, true, f.h, f.cp, nil))
+
+	require.Len(t, r.creates, 1)
+	assert.Equal(t, uint16(1500), r.creates[0].ctx.Length)
+	assert.Equal(t, uint8(0x12), r.creates[0].ctx.TCPFlags)
+}
+
+// --- benchmarks ------------------------------------------------------------
+
+// noopReporter is the cheapest possible reporter. Methods discard the event.
+type noopReporter struct{}
+
+func (noopReporter) ReportDrop(events.DropEvent)             {}
+func (noopReporter) ReportFlowCreate(events.FlowCreateEvent) {}
+func (noopReporter) ReportFlowEvict(events.FlowEvictEvent)   {}
+func (noopReporter) ReportRulesReload(events.RulesReloadEvent) {
+}
+
+// bufferedReporter demonstrates a realistic zero-alloc reporter: each event
+// is forwarded to a value-typed channel. The channel send is a memcpy into
+// the channel's pre-allocated ring buffer -- no heap traffic. A background
+// goroutine would drain these; the bench skips draining to keep the report
+// path pure.
+type bufferedReporter struct {
+	drops  chan events.DropEvent
+	flows  chan events.FlowCreateEvent
+	evicts chan events.FlowEvictEvent
+}
+
+func newBufferedReporter(cap int) *bufferedReporter {
+	return &bufferedReporter{
+		drops:  make(chan events.DropEvent, cap),
+		flows:  make(chan events.FlowCreateEvent, cap),
+		evicts: make(chan events.FlowEvictEvent, cap),
+	}
+}
+
+func (r *bufferedReporter) ReportDrop(e events.DropEvent) {
+	select {
+	case r.drops <- e:
+	default:
+	}
+}
+
+func (r *bufferedReporter) ReportFlowCreate(e events.FlowCreateEvent) {
+	select {
+	case r.flows <- e:
+	default:
+	}
+}
+
+func (r *bufferedReporter) ReportFlowEvict(e events.FlowEvictEvent) {
+	select {
+	case r.evicts <- e:
+	default:
+	}
+}
+
+func (r *bufferedReporter) ReportRulesReload(events.RulesReloadEvent) {}
+
+// pointerReporter is the anti-pattern: it takes the address of the incoming
+// event struct, which forces the callee-side copy onto the heap. Kept for
+// comparison so we can see the alloc cost an unwary reporter would incur.
+type pointerReporter struct {
+	last *events.DropEvent
+}
+
+func (r *pointerReporter) ReportDrop(e events.DropEvent) {
+	r.last = &e
+}
+
+func (r *pointerReporter) ReportFlowCreate(events.FlowCreateEvent) {}
+func (r *pointerReporter) ReportFlowEvict(events.FlowEvictEvent)   {}
+func (r *pointerReporter) ReportRulesReload(events.RulesReloadEvent) {
+}
+
+func newBenchFixture(b *testing.B) *eventFixture {
+	b.Helper()
+	l := test.NewLogger()
+
+	vpnNetworks := new(bart.Lite)
+	vpnNetworks.Insert(netip.MustParsePrefix("1.2.3.0/24"))
+
+	c := &dummyCert{
+		name:     "host1",
+		networks: []netip.Prefix{netip.MustParsePrefix("1.2.3.4/24")},
+		groups:   []string{"default-group"},
+		issuer:   "signer-shasum",
+	}
+	h := &HostInfo{
+		ConnectionState: &ConnectionState{
+			peerCert: &cert.CachedCertificate{
+				Certificate:    c,
+				InvertedGroups: map[string]struct{}{"default-group": {}},
+			},
+		},
+		vpnAddrs: []netip.Addr{netip.MustParseAddr("1.2.3.4")},
+	}
+	h.buildNetworks(vpnNetworks, c)
+
+	fw := NewFirewall(l, time.Minute, time.Minute, time.Minute, c)
+	// Inbound rule that matches our packet; outbound has no match so we can
+	// also benchmark the no-rule drop path.
+	if err := fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"any"}, "", "", "", "", ""); err != nil {
+		b.Fatal(err)
+	}
+
+	ctl := &Control{f: &Interface{firewall: fw}, l: l}
+	return &eventFixture{
+		ctl: ctl,
+		fw:  fw,
+		p: firewall.Packet{
+			LocalAddr:  netip.MustParseAddr("1.2.3.4"),
+			RemoteAddr: netip.MustParseAddr("1.2.3.4"),
+			LocalPort:  10,
+			RemotePort: 90,
+			Protocol:   firewall.ProtoUDP,
+		},
+		h:  h,
+		cp: cert.NewCAPool(),
+	}
+}
+
+// BenchmarkFirewallDropPath measures the cost of Firewall.Drop on a packet
+// that reaches the no-matching-rule branch (the longest drop path). Compare
+// reporter shapes:
+//
+//	nilReporter      -- no reporter installed (feature cost when off)
+//	noopReporter     -- reporter installed, methods discard args (minimum on-cost)
+//	bufferedReporter -- realistic zero-alloc reporter: value-typed channels
+//	pointerReporter  -- anti-pattern that takes &composite-literal (allocates)
+func BenchmarkFirewallDropPath(b *testing.B) {
+	run := func(b *testing.B, install func(*Control)) {
+		f := newBenchFixture(b)
+		install(f.ctl)
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			_ = f.firewall().Drop(f.p, firewall.PacketContext{}, false, f.h, f.cp, nil)
+		}
+	}
+
+	b.Run("nilReporter", func(b *testing.B) { run(b, func(*Control) {}) })
+	b.Run("noopReporter", func(b *testing.B) {
+		run(b, func(c *Control) { c.SetFirewallEventReporter(noopReporter{}) })
+	})
+	b.Run("bufferedReporter", func(b *testing.B) {
+		run(b, func(c *Control) { c.SetFirewallEventReporter(newBufferedReporter(1024)) })
+	})
+	b.Run("pointerReporter", func(b *testing.B) {
+		run(b, func(c *Control) { c.SetFirewallEventReporter(&pointerReporter{}) })
+	})
+}
+
+// BenchmarkConntrackCreate measures Firewall.Drop for an allowed inbound
+// packet on a fresh conntrack (so addConn fires each iteration).
+func BenchmarkConntrackCreate(b *testing.B) {
+	run := func(b *testing.B, install func(*Control)) {
+		f := newBenchFixture(b)
+		install(f.ctl)
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			resetConntrack(f.firewall())
+			_ = f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil)
+		}
+	}
+	b.Run("nilReporter", func(b *testing.B) { run(b, func(*Control) {}) })
+	b.Run("noopReporter", func(b *testing.B) {
+		run(b, func(c *Control) { c.SetFirewallEventReporter(noopReporter{}) })
+	})
+	b.Run("bufferedReporter", func(b *testing.B) {
+		run(b, func(c *Control) { c.SetFirewallEventReporter(newBufferedReporter(1024)) })
+	})
+}
+
+// BenchmarkConntrackHit measures the hot path where a flow is already in
+// conntrack and short-circuits rule evaluation. The reporter slot is checked
+// only on create/evict, so this bench should show the reporter having zero
+// impact regardless of install state.
+func BenchmarkConntrackHit(b *testing.B) {
+	b.Run("nilReporter", func(b *testing.B) {
+		f := newBenchFixture(b)
+		// Prime conntrack.
+		require.NoError(b, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			_ = f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil)
+		}
+	})
+
+	b.Run("noopReporter", func(b *testing.B) {
+		f := newBenchFixture(b)
+		f.ctl.SetFirewallEventReporter(noopReporter{})
+		require.NoError(b, f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil))
+		b.ReportAllocs()
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			_ = f.firewall().Drop(f.p, firewall.PacketContext{}, true, f.h, f.cp, nil)
+		}
+	})
+}

firewall_test.go

@@ -213,44 +213,44 @@ func TestFirewall_Drop(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// Drop outbound
-	assert.Equal(t, ErrNoMatchingRule, fw.Drop(p, false, &h, cp, nil))
+	assert.Equal(t, ErrNoMatchingRule, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil))
 	// Allow inbound
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 	// Allow outbound because conntrack
-	require.NoError(t, fw.Drop(p, false, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil))
 
 	// test remote mismatch
 	oldRemote := p.RemoteAddr
 	p.RemoteAddr = netip.MustParseAddr("1.2.3.10")
-	assert.Equal(t, fw.Drop(p, false, &h, cp, nil), ErrInvalidRemoteIP)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil), ErrInvalidRemoteIP)
 	p.RemoteAddr = oldRemote
 
 	// ensure signer doesn't get in the way of group checks
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", "signer-shasum"))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "", "signer-shasum-bad"))
-	assert.Equal(t, fw.Drop(p, true, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil), ErrNoMatchingRule)
 
 	// test caSha doesn't drop on match
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", "signer-shasum-bad"))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "", "signer-shasum"))
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 
 	// ensure ca name doesn't get in the way of group checks
 	cp.CAs["signer-shasum"] = &cert.CachedCertificate{Certificate: &dummyCert{name: "ca-good"}}
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "ca-good", ""))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "ca-good-bad", ""))
-	assert.Equal(t, fw.Drop(p, true, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil), ErrNoMatchingRule)
 
 	// test caName doesn't drop on match
 	cp.CAs["signer-shasum"] = &cert.CachedCertificate{Certificate: &dummyCert{name: "ca-good"}}
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "ca-good-bad", ""))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "ca-good", ""))
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 }
 
 func TestFirewall_DropV6(t *testing.T) {
@@ -292,44 +292,44 @@ func TestFirewall_DropV6(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// Drop outbound
-	assert.Equal(t, ErrNoMatchingRule, fw.Drop(p, false, &h, cp, nil))
+	assert.Equal(t, ErrNoMatchingRule, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil))
 	// Allow inbound
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 	// Allow outbound because conntrack
-	require.NoError(t, fw.Drop(p, false, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil))
 
 	// test remote mismatch
 	oldRemote := p.RemoteAddr
 	p.RemoteAddr = netip.MustParseAddr("fd12::56")
-	assert.Equal(t, fw.Drop(p, false, &h, cp, nil), ErrInvalidRemoteIP)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil), ErrInvalidRemoteIP)
 	p.RemoteAddr = oldRemote
 
 	// ensure signer doesn't get in the way of group checks
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", "signer-shasum"))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "", "signer-shasum-bad"))
-	assert.Equal(t, fw.Drop(p, true, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil), ErrNoMatchingRule)
 
 	// test caSha doesn't drop on match
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "", "signer-shasum-bad"))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "", "signer-shasum"))
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 
 	// ensure ca name doesn't get in the way of group checks
 	cp.CAs["signer-shasum"] = &cert.CachedCertificate{Certificate: &dummyCert{name: "ca-good"}}
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "ca-good", ""))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "ca-good-bad", ""))
-	assert.Equal(t, fw.Drop(p, true, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil), ErrNoMatchingRule)
 
 	// test caName doesn't drop on match
 	cp.CAs["signer-shasum"] = &cert.CachedCertificate{Certificate: &dummyCert{name: "ca-good"}}
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"nope"}, "", "", "", "ca-good-bad", ""))
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group"}, "", "", "", "ca-good", ""))
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 }
 
 func BenchmarkFirewallTable_match(b *testing.B) {
@@ -537,10 +537,10 @@ func TestFirewall_Drop2(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// h1/c1 lacks the proper groups
-	require.ErrorIs(t, fw.Drop(p, true, &h1, cp, nil), ErrNoMatchingRule)
+	require.ErrorIs(t, fw.Drop(p, firewall.PacketContext{}, true, &h1, cp, nil), ErrNoMatchingRule)
 	// c has the proper groups
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 }
 
 func TestFirewall_Drop3(t *testing.T) {
@@ -618,18 +618,18 @@ func TestFirewall_Drop3(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// c1 should pass because host match
-	require.NoError(t, fw.Drop(p, true, &h1, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h1, cp, nil))
 	// c2 should pass because ca sha match
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p, true, &h2, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h2, cp, nil))
 	// c3 should fail because no match
 	resetConntrack(fw)
-	assert.Equal(t, fw.Drop(p, true, &h3, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, true, &h3, cp, nil), ErrNoMatchingRule)
 
 	// Test a remote address match
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 1, 1, []string{}, "", "1.2.3.4/24", "", "", ""))
-	require.NoError(t, fw.Drop(p, true, &h1, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h1, cp, nil))
 }
 
 func TestFirewall_Drop3V6(t *testing.T) {
@@ -667,7 +667,7 @@ func TestFirewall_Drop3V6(t *testing.T) {
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
 	cp := cert.NewCAPool()
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 1, 1, []string{}, "", "fd12::34/120", "", "", ""))
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 }
 
 func TestFirewall_DropConntrackReload(t *testing.T) {
@@ -709,12 +709,12 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 	cp := cert.NewCAPool()
 
 	// Drop outbound
-	assert.Equal(t, fw.Drop(p, false, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 	// Allow inbound
 	resetConntrack(fw)
-	require.NoError(t, fw.Drop(p, true, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, true, &h, cp, nil))
 	// Allow outbound because conntrack
-	require.NoError(t, fw.Drop(p, false, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil))
 
 	oldFw := fw
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
@@ -723,7 +723,7 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 	fw.rulesVersion = oldFw.rulesVersion + 1
 
 	// Allow outbound because conntrack and new rules allow port 10
-	require.NoError(t, fw.Drop(p, false, &h, cp, nil))
+	require.NoError(t, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil))
 
 	oldFw = fw
 	fw = NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
@@ -732,7 +732,7 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 	fw.rulesVersion = oldFw.rulesVersion + 1
 
 	// Drop outbound because conntrack doesn't match new ruleset
-	assert.Equal(t, fw.Drop(p, false, &h, cp, nil), ErrNoMatchingRule)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 }
 
 func TestFirewall_ICMPPortBehavior(t *testing.T) {
@@ -778,12 +778,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0
 			p.RemotePort = 0
 			// Drop outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			require.NoError(t, fw.Drop(*p, true, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, firewall.PacketContext{}, true, &h, cp, nil))
 			//now also allow outbound
-			require.NoError(t, fw.Drop(*p, false, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil))
 		})
 
 		t.Run("nonzero ports", func(t *testing.T) {
@@ -791,12 +791,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0xabcd
 			p.RemotePort = 0x1234
 			// Drop outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			require.NoError(t, fw.Drop(*p, true, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, firewall.PacketContext{}, true, &h, cp, nil))
 			//now also allow outbound
-			require.NoError(t, fw.Drop(*p, false, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil))
 		})
 	})
 
@@ -808,12 +808,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0
 			p.RemotePort = 0
 			// Drop outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			assert.Equal(t, fw.Drop(*p, true, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, true, &h, cp, nil), ErrNoMatchingRule)
 			//now also allow outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 		})
 
 		t.Run("nonzero ports, still blocked", func(t *testing.T) {
@@ -821,12 +821,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0xabcd
 			p.RemotePort = 0x1234
 			// Drop outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			assert.Equal(t, fw.Drop(*p, true, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, true, &h, cp, nil), ErrNoMatchingRule)
 			//now also allow outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 		})
 
 		t.Run("nonzero, matching ports, still blocked", func(t *testing.T) {
@@ -834,12 +834,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 80
 			p.RemotePort = 80
 			// Drop outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			assert.Equal(t, fw.Drop(*p, true, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, true, &h, cp, nil), ErrNoMatchingRule)
 			//now also allow outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 		})
 	})
 	t.Run("Any proto, any port", func(t *testing.T) {
@@ -851,12 +851,12 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0
 			p.RemotePort = 0
 			// Drop outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			require.NoError(t, fw.Drop(*p, true, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, firewall.PacketContext{}, true, &h, cp, nil))
 			//now also allow outbound
-			require.NoError(t, fw.Drop(*p, false, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil))
 		})
 
 		t.Run("nonzero ports, allowed", func(t *testing.T) {
@@ -865,15 +865,15 @@ func TestFirewall_ICMPPortBehavior(t *testing.T) {
 			p.LocalPort = 0xabcd
 			p.RemotePort = 0x1234
 			// Drop outbound
-			assert.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			assert.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 			// Allow inbound
 			resetConntrack(fw)
-			require.NoError(t, fw.Drop(*p, true, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, firewall.PacketContext{}, true, &h, cp, nil))
 			//now also allow outbound
-			require.NoError(t, fw.Drop(*p, false, &h, cp, nil))
+			require.NoError(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil))
 			//different ID is blocked
 			p.RemotePort++
-			require.Equal(t, fw.Drop(*p, false, &h, cp, nil), ErrNoMatchingRule)
+			require.Equal(t, fw.Drop(*p, firewall.PacketContext{}, false, &h, cp, nil), ErrNoMatchingRule)
 		})
 	})
 
@@ -922,7 +922,7 @@ func TestFirewall_DropIPSpoofing(t *testing.T) {
 		Protocol:   firewall.ProtoUDP,
 		Fragment:   false,
 	}
-	assert.Equal(t, fw.Drop(p, true, &h1, cp, nil), ErrInvalidRemoteIP)
+	assert.Equal(t, fw.Drop(p, firewall.PacketContext{}, true, &h1, cp, nil), ErrInvalidRemoteIP)
 }
 
 func BenchmarkLookup(b *testing.B) {
@@ -1336,7 +1336,7 @@ func (c *testcase) Test(t *testing.T, fw *Firewall) {
 	t.Helper()
 	cp := cert.NewCAPool()
 	resetConntrack(fw)
-	err := fw.Drop(c.p, true, c.h, cp, nil)
+	err := fw.Drop(c.p, firewall.PacketContext{}, true, c.h, cp, nil)
 	if c.err == nil {
 		require.NoError(t, err, "failed to not drop remote address %s", c.p.RemoteAddr)
 	} else {

inside.go

@@ -11,8 +11,8 @@ import (
 	"github.com/slackhq/nebula/routing"
 )
 
-func (f *Interface) consumeInsidePacket(packet []byte, fwPacket *firewall.Packet, nb, out []byte, q int, localCache firewall.ConntrackCache) {
-	err := newPacket(packet, false, fwPacket)
+func (f *Interface) consumeInsidePacket(packet []byte, fwPacket *firewall.Packet, fwCtx *firewall.PacketContext, nb, out []byte, q int, localCache firewall.ConntrackCache) {
+	err := newPacket(packet, false, fwPacket, fwCtx)
 	if err != nil {
 		if f.l.Level >= logrus.DebugLevel {
 			f.l.WithField("packet", packet).Debugf("Error while validating outbound packet: %s", err)
@@ -66,7 +66,7 @@ func (f *Interface) consumeInsidePacket(packet []byte, fwPacket *firewall.Packet
 		return
 	}
 
-	dropReason := f.firewall.Drop(*fwPacket, false, hostinfo, f.pki.GetCAPool(), localCache)
+	dropReason := f.firewall.Drop(*fwPacket, *fwCtx, false, hostinfo, f.pki.GetCAPool(), localCache)
 	if dropReason == nil {
 		f.sendNoMetrics(header.Message, 0, hostinfo.ConnectionState, hostinfo, netip.AddrPort{}, packet, nb, out, q)
 
@@ -211,14 +211,15 @@ func (f *Interface) getOrHandshakeConsiderRouting(fwPacket *firewall.Packet, cac
 
 func (f *Interface) sendMessageNow(t header.MessageType, st header.MessageSubType, hostinfo *HostInfo, p, nb, out []byte) {
 	fp := &firewall.Packet{}
-	err := newPacket(p, false, fp)
+	ctx := &firewall.PacketContext{}
+	err := newPacket(p, false, fp, ctx)
 	if err != nil {
 		f.l.Warnf("error while parsing outgoing packet for firewall check; %v", err)
 		return
 	}
 
 	// check if packet is in outbound fw rules
-	dropReason := f.firewall.Drop(*fp, false, hostinfo, f.pki.GetCAPool(), nil)
+	dropReason := f.firewall.Drop(*fp, *ctx, false, hostinfo, f.pki.GetCAPool(), nil)
 	if dropReason != nil {
 		if f.l.Level >= logrus.DebugLevel {
 			f.l.WithField("fwPacket", fp).

interface.go

@@ -310,10 +310,11 @@ func (f *Interface) listenOut(i int) {
 	plaintext := make([]byte, udp.MTU)
 	h := &header.H{}
 	fwPacket := &firewall.Packet{}
+	fwCtx := &firewall.PacketContext{}
 	nb := make([]byte, 12, 12)
 
 	err := li.ListenOut(func(fromUdpAddr netip.AddrPort, payload []byte) {
-		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, plaintext[:0], payload, h, fwPacket, lhh, nb, i, ctCache.Get(f.l))
+		f.readOutsidePackets(ViaSender{UdpAddr: fromUdpAddr}, plaintext[:0], payload, h, fwPacket, fwCtx, lhh, nb, i, ctCache.Get(f.l))
 	})
 
 	if err != nil && !f.closed.Load() {
@@ -328,6 +329,7 @@ func (f *Interface) listenIn(reader io.ReadWriteCloser, i int) {
 	packet := make([]byte, mtu)
 	out := make([]byte, mtu)
 	fwPacket := &firewall.Packet{}
+	fwCtx := &firewall.PacketContext{}
 	nb := make([]byte, 12, 12)
 
 	conntrackCache := firewall.NewConntrackCacheTicker(f.ctx, f.conntrackCacheTimeout)
@@ -342,7 +344,7 @@ func (f *Interface) listenIn(reader io.ReadWriteCloser, i int) {
 			break
 		}
 
-		f.consumeInsidePacket(packet[:n], fwPacket, nb, out, i, conntrackCache.Get(f.l))
+		f.consumeInsidePacket(packet[:n], fwPacket, fwCtx, nb, out, i, conntrackCache.Get(f.l))
 	}
 
 	f.l.Debugf("overlay reader %v is done", i)
@@ -400,8 +402,15 @@ func (f *Interface) reloadFirewall(c *config.C) {
 		fw.Conntrack = conntrack
 	}
 
+	fw.reporter = oldFw.reporter
+
 	f.firewall = fw
 
+	// Fire ReportRulesReload under the conntrack lock so the reporter cannot
+	// observe a FlowCreate/FlowEvict for the new rulesVersion before it
+	// observes the reload marker. Report* must be non-blocking.
+	fw.reportRulesReload(oldFw.rulesVersion, fw.rulesVersion)
+
 	oldFw.Destroy()
 	f.l.WithField("firewallHashes", fw.GetRuleHashes()).
 		WithField("oldFirewallHashes", oldFw.GetRuleHashes()).

outside.go

@@ -19,7 +19,7 @@ const (
 	minFwPacketLen = 4
 )
 
-func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache) {
+func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, fwCtx *firewall.PacketContext, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache) {
 	err := h.Parse(packet)
 	if err != nil {
 		// Hole punch packets are 0 or 1 byte big, so lets ignore printing those errors
@@ -60,7 +60,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 
 		switch h.Subtype {
 		case header.MessageNone:
-			if !f.decryptToTun(hostinfo, h.MessageCounter, out, packet, fwPacket, nb, q, localCache) {
+			if !f.decryptToTun(hostinfo, h.MessageCounter, out, packet, fwPacket, fwCtx, nb, q, localCache) {
 				return
 			}
 		case header.MessageRelay:
@@ -102,7 +102,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 					relay:     relay,
 					IsRelayed: true,
 				}
-				f.readOutsidePackets(via, out[:0], signedPayload, h, fwPacket, lhf, nb, q, localCache)
+				f.readOutsidePackets(via, out[:0], signedPayload, h, fwPacket, fwCtx, lhf, nb, q, localCache)
 				return
 			case ForwardingType:
 				// Find the target HostInfo relay object
@@ -295,7 +295,10 @@ var (
 )
 
 // newPacket validates and parses the interesting bits for the firewall out of the ip and sub protocol headers
-func newPacket(data []byte, incoming bool, fp *firewall.Packet) error {
+func newPacket(data []byte, incoming bool, fp *firewall.Packet, ctx *firewall.PacketContext) error {
+	if ctx != nil {
+		*ctx = firewall.PacketContext{}
+	}
 	if len(data) < 1 {
 		return ErrPacketTooShort
 	}
@@ -303,14 +306,14 @@ func newPacket(data []byte, incoming bool, fp *firewall.Packet) error {
 	version := int((data[0] >> 4) & 0x0f)
 	switch version {
 	case ipv4.Version:
-		return parseV4(data, incoming, fp)
+		return parseV4(data, incoming, fp, ctx)
 	case ipv6.Version:
-		return parseV6(data, incoming, fp)
+		return parseV6(data, incoming, fp, ctx)
 	}
 	return ErrUnknownIPVersion
 }
 
-func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
+func parseV6(data []byte, incoming bool, fp *firewall.Packet, ctx *firewall.PacketContext) error {
 	dataLen := len(data)
 	if dataLen < ipv6.HeaderLen {
 		return ErrIPv6PacketTooShort
@@ -355,6 +358,11 @@ func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
 				fp.RemotePort = 0
 			}
 			fp.Fragment = false
+			if ctx != nil {
+				ctx.Length = binary.BigEndian.Uint16(data[4:6]) + uint16(ipv6.HeaderLen)
+				ctx.ICMPType = data[offset]
+				ctx.ICMPCode = data[offset+1]
+			}
 			return nil
 
 		case layers.IPProtocolTCP, layers.IPProtocolUDP:
@@ -372,6 +380,12 @@ func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
 			}
 
 			fp.Fragment = false
+			if ctx != nil {
+				ctx.Length = binary.BigEndian.Uint16(data[4:6]) + uint16(ipv6.HeaderLen)
+				if proto == layers.IPProtocolTCP && dataLen >= offset+14 {
+					ctx.TCPFlags = data[offset+13]
+				}
+			}
 			return nil
 
 		case layers.IPProtocolIPv6Fragment:
@@ -423,7 +437,7 @@ func parseV6(data []byte, incoming bool, fp *firewall.Packet) error {
 	return ErrIPv6CouldNotFindPayload
 }
 
-func parseV4(data []byte, incoming bool, fp *firewall.Packet) error {
+func parseV4(data []byte, incoming bool, fp *firewall.Packet, ctx *firewall.PacketContext) error {
 	// Do we at least have an ipv4 header worth of data?
 	if len(data) < ipv4.HeaderLen {
 		return ErrIPv4PacketTooShort
@@ -480,6 +494,21 @@ func parseV4(data []byte, incoming bool, fp *firewall.Packet) error {
 		fp.RemotePort = binary.BigEndian.Uint16(data[ihl+2 : ihl+4]) //dst port
 	}
 
+	if ctx != nil {
+		ctx.Length = binary.BigEndian.Uint16(data[2:4])
+		if !fp.Fragment {
+			switch fp.Protocol {
+			case firewall.ProtoICMP:
+				ctx.ICMPType = data[ihl]
+				ctx.ICMPCode = data[ihl+1]
+			case firewall.ProtoTCP:
+				if len(data) >= ihl+14 {
+					ctx.TCPFlags = data[ihl+13]
+				}
+			}
+		}
+	}
+
 	return nil
 }
 
@@ -499,7 +528,7 @@ func (f *Interface) decrypt(hostinfo *HostInfo, mc uint64, out []byte, packet []
 	return out, nil
 }
 
-func (f *Interface) decryptToTun(hostinfo *HostInfo, messageCounter uint64, out []byte, packet []byte, fwPacket *firewall.Packet, nb []byte, q int, localCache firewall.ConntrackCache) bool {
+func (f *Interface) decryptToTun(hostinfo *HostInfo, messageCounter uint64, out []byte, packet []byte, fwPacket *firewall.Packet, fwCtx *firewall.PacketContext, nb []byte, q int, localCache firewall.ConntrackCache) bool {
 	var err error
 
 	out, err = hostinfo.ConnectionState.dKey.DecryptDanger(out, packet[:header.Len], packet[header.Len:], messageCounter, nb)
@@ -508,7 +537,7 @@ func (f *Interface) decryptToTun(hostinfo *HostInfo, messageCounter uint64, out
 		return false
 	}
 
-	err = newPacket(out, true, fwPacket)
+	err = newPacket(out, true, fwPacket, fwCtx)
 	if err != nil {
 		hostinfo.logger(f.l).WithError(err).WithField("packet", out).
 			Warnf("Error while validating inbound packet")
@@ -521,7 +550,7 @@ func (f *Interface) decryptToTun(hostinfo *HostInfo, messageCounter uint64, out
 		return false
 	}
 
-	dropReason := f.firewall.Drop(*fwPacket, true, hostinfo, f.pki.GetCAPool(), localCache)
+	dropReason := f.firewall.Drop(*fwPacket, *fwCtx, true, hostinfo, f.pki.GetCAPool(), localCache)
 	if dropReason != nil {
 		// NOTE: We give `packet` as the `out` here since we already decrypted from it and we don't need it anymore
 		// This gives us a buffer to build the reject packet in

outside_test.go

@@ -20,13 +20,13 @@ func Test_newPacket(t *testing.T) {
 	p := &firewall.Packet{}
 
 	// length fails
-	err := newPacket([]byte{}, true, p)
+	err := newPacket([]byte{}, true, p, nil)
 	require.ErrorIs(t, err, ErrPacketTooShort)
 
-	err = newPacket([]byte{0x40}, true, p)
+	err = newPacket([]byte{0x40}, true, p, nil)
 	require.ErrorIs(t, err, ErrIPv4PacketTooShort)
 
-	err = newPacket([]byte{0x60}, true, p)
+	err = newPacket([]byte{0x60}, true, p, nil)
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// length fail with ip options
@@ -39,15 +39,15 @@ func Test_newPacket(t *testing.T) {
 	}
 
 	b, _ := h.Marshal()
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 	require.ErrorIs(t, err, ErrIPv4InvalidHeaderLength)
 
 	// not an ipv4 packet
-	err = newPacket([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p)
+	err = newPacket([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p, nil)
 	require.ErrorIs(t, err, ErrUnknownIPVersion)
 
 	// invalid ihl
-	err = newPacket([]byte{4<<4 | (8 >> 2 & 0x0f), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p)
+	err = newPacket([]byte{4<<4 | (8 >> 2 & 0x0f), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, true, p, nil)
 	require.ErrorIs(t, err, ErrIPv4InvalidHeaderLength)
 
 	// account for variable ip header length - incoming
@@ -62,7 +62,7 @@ func Test_newPacket(t *testing.T) {
 
 	b, _ = h.Marshal()
 	b = append(b, []byte{0, 3, 0, 4}...)
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
@@ -84,7 +84,7 @@ func Test_newPacket(t *testing.T) {
 
 	b, _ = h.Marshal()
 	b = append(b, []byte{0, 5, 0, 6}...)
-	err = newPacket(b, false, p)
+	err = newPacket(b, false, p, nil)
 
 	require.NoError(t, err)
 	assert.Equal(t, uint8(2), p.Protocol)
@@ -114,7 +114,7 @@ func Test_newPacket_v6(t *testing.T) {
 	err := gopacket.SerializeLayers(buffer, opt, &ip)
 	require.NoError(t, err)
 
-	err = newPacket(buffer.Bytes(), true, p)
+	err = newPacket(buffer.Bytes(), true, p, nil)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A v6 packet with a hop-by-hop extension
@@ -148,12 +148,12 @@ func Test_newPacket_v6(t *testing.T) {
 
 	// A full IPv6 header and 1 byte in the first extension, but missing
 	// the length byte.
-	err = newPacket(buffer.Bytes()[:41], true, p)
+	err = newPacket(buffer.Bytes()[:41], true, p, nil)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A full IPv6 header plus 1 full extension, but only 1 byte of the
 	// next layer, missing length byte
-	err = newPacket(buffer.Bytes()[:49], true, p)
+	err = newPacket(buffer.Bytes()[:49], true, p, nil)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 	err = nil
 
@@ -173,7 +173,7 @@ func Test_newPacket_v6(t *testing.T) {
 
 	buffer.Clear()
 	require.NoError(t, gopacket.SerializeLayers(buffer, opt, &ip, &icmp))
-	require.Error(t, newPacket(buffer.Bytes(), true, p))
+	require.Error(t, newPacket(buffer.Bytes(), true, p, nil))
 
 	buffer.Clear()
 	echo := layers.ICMPv6Echo{
@@ -181,7 +181,7 @@ func Test_newPacket_v6(t *testing.T) {
 		SeqNumber:  1234,
 	}
 	require.NoError(t, gopacket.SerializeLayers(buffer, opt, &ip, &icmp, &echo))
-	require.NoError(t, newPacket(buffer.Bytes(), true, p))
+	require.NoError(t, newPacket(buffer.Bytes(), true, p, nil))
 	assert.Equal(t, uint8(layers.IPProtocolICMPv6), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.LocalAddr)
@@ -192,7 +192,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// A good ESP packet
 	b := buffer.Bytes()
 	b[6] = byte(layers.IPProtocolESP)
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(layers.IPProtocolESP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -204,7 +204,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// A good None packet
 	b = buffer.Bytes()
 	b[6] = byte(layers.IPProtocolNoNextHeader)
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(layers.IPProtocolNoNextHeader), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -216,7 +216,7 @@ func Test_newPacket_v6(t *testing.T) {
 	// An unknown protocol packet
 	b = buffer.Bytes()
 	b[6] = 255 // 255 is a reserved protocol number
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 
 	// A good UDP packet
@@ -243,7 +243,7 @@ func Test_newPacket_v6(t *testing.T) {
 	b = buffer.Bytes()
 
 	// incoming
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -253,7 +253,7 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// outgoing
-	err = newPacket(b, false, p)
+	err = newPacket(b, false, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
@@ -263,14 +263,14 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// Too short UDP packet
-	err = newPacket(b[:len(b)-10], false, p) // pull off the last 10 bytes
+	err = newPacket(b[:len(b)-10], false, p, nil) // pull off the last 10 bytes
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// A good TCP packet
 	b[6] = byte(layers.IPProtocolTCP)
 
 	// incoming
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -280,7 +280,7 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// outgoing
-	err = newPacket(b, false, p)
+	err = newPacket(b, false, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoTCP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
@@ -290,7 +290,7 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// Too short TCP packet
-	err = newPacket(b[:len(b)-10], false, p) // pull off the last 10 bytes
+	err = newPacket(b[:len(b)-10], false, p, nil) // pull off the last 10 bytes
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// A good UDP packet with an AH header
@@ -325,7 +325,7 @@ func Test_newPacket_v6(t *testing.T) {
 	b = append(b, ahb...)
 	b = append(b, udpHeader...)
 
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, uint8(firewall.ProtoUDP), p.Protocol)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
@@ -335,12 +335,12 @@ func Test_newPacket_v6(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// Ensure buffer bounds checking during processing
-	err = newPacket(b[:41], true, p)
+	err = newPacket(b[:41], true, p, nil)
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 
 	// Invalid AH header
 	b = buffer.Bytes()
-	err = newPacket(b, true, p)
+	err = newPacket(b, true, p, nil)
 	require.ErrorIs(t, err, ErrIPv6CouldNotFindPayload)
 }
 
@@ -388,7 +388,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	firstFrag = append(firstFrag, []byte{0xde, 0xad, 0xbe, 0xef}...)
 
 	// Test first fragment incoming
-	err = newPacket(firstFrag, true, p)
+	err = newPacket(firstFrag, true, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.LocalAddr)
@@ -398,7 +398,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	assert.False(t, p.Fragment)
 
 	// Test first fragment outgoing
-	err = newPacket(firstFrag, false, p)
+	err = newPacket(firstFrag, false, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.RemoteAddr)
@@ -427,7 +427,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	secondFrag = append(secondFrag, []byte{0xde, 0xad, 0xbe, 0xef}...)
 
 	// Test second fragment incoming
-	err = newPacket(secondFrag, true, p)
+	err = newPacket(secondFrag, true, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.RemoteAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.LocalAddr)
@@ -437,7 +437,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	assert.True(t, p.Fragment)
 
 	// Test second fragment outgoing
-	err = newPacket(secondFrag, false, p)
+	err = newPacket(secondFrag, false, p, nil)
 	require.NoError(t, err)
 	assert.Equal(t, netip.MustParseAddr("ff02::2"), p.LocalAddr)
 	assert.Equal(t, netip.MustParseAddr("ff02::1"), p.RemoteAddr)
@@ -447,7 +447,7 @@ func Test_newPacket_ipv6Fragment(t *testing.T) {
 	assert.True(t, p.Fragment)
 
 	// Too short of a fragment packet
-	err = newPacket(secondFrag[:len(secondFrag)-10], false, p)
+	err = newPacket(secondFrag[:len(secondFrag)-10], false, p, nil)
 	require.ErrorIs(t, err, ErrIPv6PacketTooShort)
 }
 
@@ -529,7 +529,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("Normal", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = parseV6(normalPacket, true, fp); err != nil {
+			if err = parseV6(normalPacket, true, fp, nil); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -537,7 +537,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("FirstFragment", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = parseV6(firstFrag, true, fp); err != nil {
+			if err = parseV6(firstFrag, true, fp, nil); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -545,7 +545,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("SecondFragment", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = parseV6(secondFrag, true, fp); err != nil {
+			if err = parseV6(secondFrag, true, fp, nil); err != nil {
 				b.Fatal(err)
 			}
 		}
@@ -590,7 +590,7 @@ func BenchmarkParseV6(b *testing.B) {
 
 	b.Run("200 HopByHop headers", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			if err = parseV6(evilBytes, false, fp); err != nil {
+			if err = parseV6(evilBytes, false, fp, nil); err != nil {
 				b.Fatal(err)
 			}
 		}