fix(router): nft tables limit number of peers source

Author: nhenneaux

client/firewall/nftables/manager_linux_test.go

@@ -386,6 +386,56 @@ func TestNftablesManagerCompatibilityWithIptables(t *testing.T) {
 	verifyIptablesOutput(t, stdout, stderr)
 }
 
+func TestNftablesManagerCompatibilityWithIptablesFor10kPrefixes(t *testing.T) {
+	if check() != NFTABLES {
+		t.Skip("nftables not supported on this system")
+	}
+
+	if _, err := exec.LookPath("iptables-save"); err != nil {
+		t.Skipf("iptables-save not available on this system: %v", err)
+	}
+
+	// First ensure iptables-nft tables exist by running iptables-save
+	stdout, stderr := runIptablesSave(t)
+	verifyIptablesOutput(t, stdout, stderr)
+
+	manager, err := Create(ifaceMock, iface.DefaultMTU)
+	require.NoError(t, err, "failed to create manager")
+	require.NoError(t, manager.Init(nil))
+
+	t.Cleanup(func() {
+		err := manager.Close(nil)
+		require.NoError(t, err, "failed to reset manager state")
+
+		// Verify iptables output after reset
+		stdout, stderr := runIptablesSave(t)
+		verifyIptablesOutput(t, stdout, stderr)
+	})
+
+	const octet2Count = 25
+	const octet3Count = 255
+	prefixes := make([]netip.Prefix, 0, (octet2Count-1)*(octet3Count-1))
+	for i := 1; i < octet2Count; i++ {
+		for j := 1; j < octet3Count; j++ {
+			addr := netip.AddrFrom4([4]byte{192, byte(j), byte(i), 0})
+			prefixes = append(prefixes, netip.PrefixFrom(addr, 24))
+		}
+	}
+	_, err = manager.AddRouteFiltering(
+		nil,
+		prefixes,
+		fw.Network{Prefix: netip.MustParsePrefix("10.2.0.0/24")},
+		fw.ProtocolTCP,
+		nil,
+		&fw.Port{Values: []uint16{443}},
+		fw.ActionAccept,
+	)
+	require.NoError(t, err, "failed to add route filtering rule")
+
+	stdout, stderr = runIptablesSave(t)
+	verifyIptablesOutput(t, stdout, stderr)
+}
+
 func compareExprsIgnoringCounters(t *testing.T, got, want []expr.Any) {
 	t.Helper()
 	require.Equal(t, len(got), len(want), "expression count mismatch")

client/firewall/nftables/router_linux.go

@@ -346,25 +346,11 @@ func (r *router) AddRouteFiltering(
 	}
 
 	chain := r.chains[chainNameRoutingFw]
-	var exprs []expr.Any
-
-	var source firewall.Network
-	switch {
-	case len(sources) == 1 && sources[0].Bits() == 0:
-		// If it's 0.0.0.0/0, we don't need to add any source matching
-	case len(sources) == 1:
-		// If there's only one source, we can use it directly
-		source.Prefix = sources[0]
-	default:
-		// If there are multiple sources, use a set
-		source.Set = firewall.NewPrefixSet(sources)
-	}
 
-	sourceExp, err := r.applyNetwork(source, sources, true)
+	exprs, err := r.applySources(sources)
 	if err != nil {
-		return nil, fmt.Errorf("apply source: %w", err)
+		return nil, err
 	}
-	exprs = append(exprs, sourceExp...)
 
 	destExp, err := r.applyNetwork(destination, nil, false)
 	if err != nil {
@@ -425,6 +411,42 @@ func (r *router) AddRouteFiltering(
 	return ruleKey, nil
 }
 
+func (r *router) applySources(sources []netip.Prefix) ([]expr.Any, error) {
+	var exprs []expr.Any
+
+	var source firewall.Network
+	if len(sources) == 1 {
+		if sources[0].Bits() == 0 {
+			// If it's 0.0.0.0/0, we don't need to add any source matching
+		} else { // If there's only one source, we can use it directly
+			source.Prefix = sources[0]
+		}
+		sourceExp, err := r.applyNetwork(source, sources, true)
+		if err != nil {
+			return nil, fmt.Errorf("apply source: %w", err)
+		}
+		exprs = append(exprs, sourceExp...)
+	} else { // If there are multiple sources, use a set
+		var subEnd int
+		maxSize := 200
+		for subStart := 0; subStart < len(sources); subStart += maxSize {
+			subEnd += maxSize
+			if subEnd > len(sources) {
+				subEnd = len(sources)
+			}
+			subSources := sources[subStart:subEnd]
+			source.Set = firewall.NewPrefixSet(subSources)
+
+			sourceExp, err := r.applyNetwork(source, subSources, true)
+			if err != nil {
+				return nil, fmt.Errorf("apply source: %w", err)
+			}
+			exprs = append(exprs, sourceExp...)
+		}
+	}
+	return exprs, nil
+}
+
 func (r *router) getIpSet(set firewall.Set, prefixes []netip.Prefix, isSource bool) ([]expr.Any, error) {
 	ref, err := r.ipsetCounter.Increment(set.HashedName(), setInput{
 		set:      set,