Attach conntrack helpers via ct helper objects

internal/nftables/diff_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/google/nftables/expr"
+	"golang.org/x/sys/unix"
 )
 
 func TestRestoreChangeSet(t *testing.T) {
@@ -64,3 +65,42 @@ func TestRestoreChangeSetEmptySnapshotRemovesAll(t *testing.T) {
 		t.Errorf("expected 1 remove 0 add, got %d/%d", len(cs.Remove), len(cs.Add))
 	}
 }
+
+func TestDiffHelpers(t *testing.T) {
+	h := func(name, typ string, l3 uint16, l4 uint8) Helper {
+		return Helper{Name: name, Helper: expr.CtHelper{Name: typ, L3Proto: l3, L4Proto: l4}}
+	}
+	ftp := h("ftp", "ftp", unix.NFPROTO_INET, unix.IPPROTO_TCP)
+	tftp := h("tftp", "tftp", unix.NFPROTO_INET, unix.IPPROTO_UDP)
+	sipUDP := h("sip", "sip", unix.NFPROTO_INET, unix.IPPROTO_UDP)
+	sipTCP := h("sip", "sip", unix.NFPROTO_INET, unix.IPPROTO_TCP)
+
+	current := &FirewallState{Helpers: []Helper{tftp, ftp, sipUDP}}
+	desired := &FirewallState{Helpers: []Helper{ftp, sipTCP}}
+
+	cs := computeDiff(current, desired)
+	if !reflect.DeepEqual(cs.RemoveHelpers, []string{"tftp", "sip"}) {
+		t.Errorf("remove = %v", cs.RemoveHelpers)
+	}
+	if !reflect.DeepEqual(cs.AddHelpers, []Helper{sipTCP}) {
+		t.Errorf("add = %v", cs.AddHelpers)
+	}
+
+	// Restore recreates every helper so kernel listing order matches the snapshot.
+	cs = restoreChangeSet(desired, current)
+	if !reflect.DeepEqual(cs.RemoveHelpers, []string{"ftp", "sip"}) || !reflect.DeepEqual(cs.AddHelpers, current.Helpers) {
+		t.Errorf("restore = -%v +%v", cs.RemoveHelpers, cs.AddHelpers)
+	}
+
+	live := &FirewallState{Helpers: []Helper{h("pptp", "pptp", unix.NFPROTO_IPV4, unix.IPPROTO_TCP)}}
+	want := &FirewallState{Helpers: []Helper{h("pptp", "pptp", unix.NFPROTO_INET, unix.IPPROTO_TCP)}}
+	if cs := computeDiff(live, want); !cs.Empty() {
+		t.Errorf("kernel-narrowed l3proto should not diff: %+v", cs)
+	}
+	if cs := computeDiff(desired, desired); !cs.Empty() {
+		t.Errorf("identical helpers should be empty: %+v", cs)
+	}
+	if cs := computeDiff(&FirewallState{}, desired); cs.Empty() {
+		t.Error("missing helpers should not be empty")
+	}
+}