set: add set support auto-merge (#271)

Signed-off-by: Asutorufa <16442314+Asutorufa@users.noreply.github.com>

nftables_test.go

@@ -3498,6 +3498,66 @@ func TestCreateUseNamedSet(t *testing.T) {
 	}
 }
 
+func TestCreateAutoMergeSet(t *testing.T) {
+	// Create a new network namespace to test these operations,
+	// and tear down the namespace at test completion.
+	c, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	defer nftest.CleanupSystemConn(t, newNS)
+	// Clear all rules at the beginning + end of the test.
+	c.FlushRuleset()
+	defer c.FlushRuleset()
+
+	filter := c.AddTable(&nftables.Table{
+		Family: nftables.TableFamilyIPv4,
+		Name:   "filter",
+	})
+
+	portSet := &nftables.Set{
+		Table:     filter,
+		Name:      "test",
+		KeyType:   nftables.TypeInetService,
+		Interval:  true,
+		AutoMerge: true,
+	}
+	if err := c.AddSet(portSet, nil); err != nil {
+		t.Errorf("c.AddSet(portSet) failed: %v", err)
+	}
+	if err := c.SetAddElements(portSet, []nftables.SetElement{{Key: binaryutil.BigEndian.PutUint16(22)}}); err != nil {
+		t.Errorf("c.SetVal(portSet) failed: %v", err)
+	}
+
+	ipSet := &nftables.Set{
+		Table:     filter,
+		Name:      "IPs_4_dayz",
+		KeyType:   nftables.TypeIPAddr,
+		Interval:  true,
+		AutoMerge: true,
+	}
+	if err := c.AddSet(ipSet, []nftables.SetElement{{Key: []byte(net.ParseIP("192.168.1.64").To4())}}); err != nil {
+		t.Errorf("c.AddSet(ipSet) failed: %v", err)
+	}
+	if err := c.SetAddElements(ipSet, []nftables.SetElement{{Key: []byte(net.ParseIP("192.168.1.42").To4())}}); err != nil {
+		t.Errorf("c.SetVal(ipSet) failed: %v", err)
+	}
+	if err := c.Flush(); err != nil {
+		t.Errorf("c.Flush() failed: %v", err)
+	}
+
+	sets, err := c.GetSets(filter)
+	if err != nil {
+		t.Errorf("c.GetSets() failed: %v", err)
+	}
+	if len(sets) != 2 {
+		t.Fatalf("len(sets) = %d, want 2", len(sets))
+	}
+	if !sets[0].AutoMerge {
+		t.Errorf("set[0].AutoMerge = %v, want true", sets[0].AutoMerge)
+	}
+	if !sets[1].AutoMerge {
+		t.Errorf("set[1].AutoMerge = %v, want true", sets[1].AutoMerge)
+	}
+}
+
 func TestIP6SetAddElements(t *testing.T) {
 	// Create a new network namespace to test these operations,
 	// and tear down the namespace at test completion.

set.go

@@ -21,10 +21,10 @@ import (
 	"strings"
 	"time"
 
+	"github.com/google/nftables/binaryutil"
 	"github.com/google/nftables/expr"
 	"github.com/google/nftables/internal/parseexprfunc"
-
+	"github.com/google/nftables/userdata"
-	"github.com/google/nftables/binaryutil"
 	"github.com/mdlayher/netlink"
 	"golang.org/x/sys/unix"
 )
@@ -249,6 +249,7 @@ type Set struct {
 	Anonymous  bool
 	Constant   bool
 	Interval   bool
+	AutoMerge  bool
 	IsMap      bool
 	HasTimeout bool
 	Counter    bool
@@ -580,15 +581,27 @@ func (cc *Conn) AddSet(s *Set, vals []SetElement) error {
 		// Marshal concat size description as set description
 		tableInfo = append(tableInfo, netlink.Attribute{Type: unix.NLA_F_NESTED | unix.NFTA_SET_DESC, Data: concatBytes})
 	}
+
+	// https://git.netfilter.org/libnftnl/tree/include/udata.h#n17
+	var userData []byte
+
 	if s.Anonymous || s.Constant || s.Interval || s.KeyByteOrder == binaryutil.BigEndian {
-		tableInfo = append(tableInfo,
 		// Semantically useless - kept for binary compatability with nft
-			netlink.Attribute{Type: unix.NFTA_SET_USERDATA, Data: []byte("\x00\x04\x02\x00\x00\x00")})
+		userData = userdata.AppendUint32(userData, userdata.NFTNL_UDATA_SET_KEYBYTEORDER, 2)
 	} else if s.KeyByteOrder == binaryutil.NativeEndian {
 		// Per https://git.netfilter.org/nftables/tree/src/mnl.c?id=187c6d01d35722618c2711bbc49262c286472c8f#n1165
-		tableInfo = append(tableInfo,
+		userData = userdata.AppendUint32(userData, userdata.NFTNL_UDATA_SET_KEYBYTEORDER, 1)
-			netlink.Attribute{Type: unix.NFTA_SET_USERDATA, Data: []byte("\x00\x04\x01\x00\x00\x00")})
 	}
+
+	if s.Interval && s.AutoMerge {
+		// https://git.netfilter.org/nftables/tree/src/mnl.c?id=187c6d01d35722618c2711bbc49262c286472c8f#n1174
+		userData = userdata.AppendUint32(userData, userdata.NFTNL_UDATA_SET_MERGE_ELEMENTS, 1)
+	}
+
+	if len(userData) > 0 {
+		tableInfo = append(tableInfo, netlink.Attribute{Type: unix.NFTA_SET_USERDATA, Data: userData})
+	}
+
 	if s.Counter {
 		data, err := netlink.MarshalAttributes([]netlink.Attribute{
 			{Type: unix.NFTA_LIST_ELEM, Data: []byte("counter\x00")},
@@ -740,6 +753,10 @@ func setsFromMsg(msg netlink.Message) (*Set, error) {
 			set.DataType = dt
 		case unix.NFTA_SET_DATA_LEN:
 			set.DataType.Bytes = binary.BigEndian.Uint32(ad.Bytes())
+		case unix.NFTA_SET_USERDATA:
+			data := ad.Bytes()
+			value, ok := userdata.GetUint32(data, userdata.NFTNL_UDATA_SET_MERGE_ELEMENTS)
+			set.AutoMerge = ok && value == 1
 		}
 	}
 	return &set, nil

userdata/userdata.go

@@ -31,6 +31,21 @@ const (
 	TypesCount
 )
 
+// TLV type values are defined in:
+// https://git.netfilter.org/libnftnl/tree/include/libnftnl/udata.h#n39
+const (
+	NFTNL_UDATA_SET_KEYBYTEORDER Type = iota
+	NFTNL_UDATA_SET_DATABYTEORDER
+	NFTNL_UDATA_SET_MERGE_ELEMENTS
+	NFTNL_UDATA_SET_KEY_TYPEOF
+	NFTNL_UDATA_SET_DATA_TYPEOF
+	NFTNL_UDATA_SET_EXPR
+	NFTNL_UDATA_SET_DATA_INTERVAL
+	NFTNL_UDATA_SET_COMMENT
+
+	NFTNL_UDATA_SET_MAX
+)
+
 func Append(udata []byte, typ Type, data []byte) []byte {
 	udata = append(udata, byte(typ), byte(len(data)))
 	udata = append(udata, data...)