Build Housecarl 0.1.0: the nftables firewall manager

Zones, address sets (IPv4 and IPv6 mixed, dynamic sets with timeouts) and
services, ordered rules in the early, input, forward and output chains,
port forwards with hairpin NAT and IPv6 pinholes, source NAT, redirects,
and switchable built-ins (loopback, conntrack, ICMPv6, antispoofing, MSS
clamping, DHCPv6 client, flowtable). Every change is validated, checked
with nft -c and applied in one transaction to Housecarl's own table,
inet housecarl; changes made over the network roll back unless
confirmed, and the confirmed ruleset is loaded at boot by
housecarl-ruleset.service. An empty configuration applies nothing.

Also: hit counters and the drop log (nflog), 'hc import' of an existing
nftables ruleset and 'hc takeover', the hc CLI, the REST API and the web
UI, users, scoped tokens (sets:write:NAME), the audit log, the web UI's
certificate through Jarl, Debian packages, docs, unit tests with real
nft 1.1.3, and an e2e test with real traffic (71 checks).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/engine/engine_test.go

@@ -0,0 +1,175 @@
+package engine
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"housecarl/internal/auth"
+	"housecarl/internal/model"
+	"housecarl/internal/store"
+)
+
+func newEngine(t *testing.T) *Engine {
+	t.Helper()
+	st, err := store.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	e, err := New(context.Background(), st, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return e
+}
+
+var admin = &auth.Principal{User: &model.User{ID: 1, Username: "admin", Admin: true}, Method: "session"}
+
+// fakeFirewall records what it was asked to apply.
+type fakeFirewall struct {
+	applied  []*model.State
+	checkErr error
+	applyErr error
+}
+
+func (f *fakeFirewall) Check(_ context.Context, st *model.State) error { return f.checkErr }
+func (f *fakeFirewall) Apply(_ context.Context, st *model.State) error {
+	if f.applyErr != nil {
+		return f.applyErr
+	}
+	f.applied = append(f.applied, st.Clone())
+	return nil
+}
+
+func addWAN(t *testing.T, e *Engine) int64 {
+	t.Helper()
+	var id int64
+	res, err := e.Apply(context.Background(), admin, "", Options{Via: "cli"}, func(st *model.State, newID func() int64) error {
+		id = newID()
+		st.Zones = append(st.Zones, &model.Zone{ID: id, Name: "wan", Interfaces: []string{" wan ", "wan", "ppp*"}, External: true})
+		return nil
+	})
+	if err != nil || !res.Applied || res.HistoryID == 0 {
+		t.Fatalf("apply: %+v %v", res, err)
+	}
+	return id
+}
+
+func TestApplyNormalizesAndRecords(t *testing.T) {
+	e := newEngine(t)
+	fw := &fakeFirewall{}
+	e.Firewall = fw
+	id := addWAN(t, e)
+	z := e.State().ByID(model.KindZone, id).(*model.Zone)
+	if strings.Join(z.Interfaces, ",") != "wan,ppp*" {
+		t.Errorf("interfaces not normalized: %q", z.Interfaces)
+	}
+	if len(fw.applied) != 1 || len(fw.applied[0].Zones) != 1 {
+		t.Errorf("firewall got %+v", fw.applied)
+	}
+	h, _ := e.Store().ListHistory(context.Background(), 10, 0)
+	if len(h) != 1 || h[0].Description != "create zone wan" || h[0].Via != "cli" || h[0].Username != "admin" {
+		t.Errorf("history %+v", h[0])
+	}
+	// Nothing changed: nothing recorded or applied.
+	res, err := e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, _ func() int64) error { return nil })
+	if err != nil || res.Applied || len(res.Changes) != 0 || len(fw.applied) != 1 {
+		t.Errorf("empty change: %+v %v", res, err)
+	}
+}
+
+func TestValidationAndFirewallRefusals(t *testing.T) {
+	e := newEngine(t)
+	fw := &fakeFirewall{}
+	e.Firewall = fw
+	addWAN(t, e)
+	addRule := func(r *model.Rule) (*Result, error) {
+		return e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
+			r.ID = newID()
+			st.Rules = append(st.Rules, r)
+			return nil
+		})
+	}
+	// Validation: an unknown set.
+	_, err := addRule(&model.Rule{Chain: model.ChainInput, Position: 1, Action: model.ActionAccept, Match: model.Match{Sources: []string{"trusted"}}})
+	if ee, ok := AsError(err); !ok || ee.Kind != KindValidation || ee.Problems[0].Code != "unknown_set" {
+		t.Errorf("unknown set: %v", err)
+	}
+	// nftables refuses: nothing applied or saved.
+	fw.checkErr = errors.New("syntax error")
+	_, err = addRule(&model.Rule{Chain: model.ChainInput, Position: 1, Action: model.ActionAccept, Raw: "bogus"})
+	if ee, ok := AsError(err); !ok || ee.Kind != KindFirewall {
+		t.Errorf("refused ruleset: %v", err)
+	}
+	// Applying fails: nothing saved.
+	fw.checkErr, fw.applyErr = nil, errors.New("netlink: busy")
+	_, err = addRule(&model.Rule{Chain: model.ChainInput, Position: 1, Action: model.ActionAccept, Match: model.Match{Services: []string{"ssh"}}})
+	if ee, ok := AsError(err); !ok || ee.Kind != KindFirewall || !strings.Contains(ee.Message, "nothing was changed") {
+		t.Errorf("failed apply: %v", err)
+	}
+	if len(e.State().Rules) != 0 {
+		t.Errorf("rules saved after failures: %+v", e.State().Rules)
+	}
+	// A dry run is checked, but neither applied nor saved.
+	fw.applyErr = nil
+	before := len(fw.applied)
+	res, err := e.Apply(context.Background(), admin, "", Options{DryRun: true}, func(st *model.State, newID func() int64) error {
+		st.Rules = append(st.Rules, &model.Rule{ID: newID(), Chain: model.ChainInput, Position: 1, Action: model.ActionDrop})
+		return nil
+	})
+	if err != nil || res.Applied || len(res.Changes) != 1 || len(fw.applied) != before {
+		t.Errorf("dry run: %+v %v", res, err)
+	}
+}
+
+func TestRevertAppliesThePreviousRuleset(t *testing.T) {
+	e := newEngine(t)
+	fw := &fakeFirewall{}
+	e.Firewall = fw
+	addWAN(t, e)
+	res, err := e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
+		st.Settings.ForwardPolicy = model.PolicyAccept
+		return nil
+	})
+	if err != nil || !res.Applied {
+		t.Fatal(err)
+	}
+	if _, err := e.Revert(context.Background(), admin, res.HistoryID, Options{}); err != nil {
+		t.Fatal(err)
+	}
+	last := fw.applied[len(fw.applied)-1]
+	if last.Settings.ForwardPolicy != model.PolicyDrop || e.State().Settings.ForwardPolicy != model.PolicyDrop {
+		t.Errorf("after revert: applied %s, state %s", last.Settings.ForwardPolicy, e.State().Settings.ForwardPolicy)
+	}
+	// Undoing it twice is refused.
+	if _, err := e.Revert(context.Background(), admin, res.HistoryID, Options{}); err == nil {
+		t.Error("second undo accepted")
+	}
+}
+
+func TestPositionsStayStableUntilCrowded(t *testing.T) {
+	e := newEngine(t)
+	for i := 0; i < 3; i++ {
+		e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
+			st.Rules = append(st.Rules, &model.Rule{ID: newID(), Chain: model.ChainInput, Position: float64(i + 1), Action: model.ActionAccept,
+				Match: model.Match{Services: []string{"ssh"}}})
+			return nil
+		})
+	}
+	// Inserting between two rules changes only the new one.
+	res, err := e.Apply(context.Background(), admin, "", Options{}, func(st *model.State, newID func() int64) error {
+		st.Rules = append(st.Rules, &model.Rule{ID: newID(), Chain: model.ChainInput, Position: 1.5, Action: model.ActionDrop})
+		return nil
+	})
+	if err != nil || len(res.Changes) != 1 {
+		t.Fatalf("insert: %+v %v", res, err)
+	}
+	var order []string
+	for _, r := range e.State().Rules {
+		order = append(order, r.Action)
+	}
+	if strings.Join(order, ",") != "accept,drop,accept,accept" {
+		t.Errorf("order %v", order)
+	}
+}