Add bitwise decoder logic (#71)

expr/bitwise.go

@@ -15,7 +15,7 @@
 package expr
 
 import (
-	"fmt"
+	"encoding/binary"
 
 	"github.com/google/nftables/binaryutil"
 	"github.com/mdlayher/netlink"
@@ -61,5 +61,42 @@ func (e *Bitwise) marshal() ([]byte, error) {
 }
 
 func (e *Bitwise) unmarshal(data []byte) error {
-	return fmt.Errorf("not yet implemented")
+	ad, err := netlink.NewAttributeDecoder(data)
+	if err != nil {
+		return err
+	}
+	ad.ByteOrder = binary.BigEndian
+	for ad.Next() {
+		switch ad.Type() {
+		case unix.NFTA_BITWISE_SREG:
+			e.SourceRegister = ad.Uint32()
+		case unix.NFTA_BITWISE_DREG:
+			e.DestRegister = ad.Uint32()
+		case unix.NFTA_BITWISE_LEN:
+			e.Len = ad.Uint32()
+		case unix.NFTA_BITWISE_MASK:
+			// Since NFTA_BITWISE_MASK is nested, it requires additional decoding
+			ad.Nested(func(nad *netlink.AttributeDecoder) error {
+				for nad.Next() {
+					switch nad.Type() {
+					case unix.NFTA_DATA_VALUE:
+						e.Mask = nad.Bytes()
+					}
+				}
+				return nil
+			})
+		case unix.NFTA_BITWISE_XOR:
+			// Since NFTA_BITWISE_XOR is nested, it requires additional decoding
+			ad.Nested(func(nad *netlink.AttributeDecoder) error {
+				for nad.Next() {
+					switch nad.Type() {
+					case unix.NFTA_DATA_VALUE:
+						e.Xor = nad.Bytes()
+					}
+				}
+				return nil
+			})
+		}
+	}
+	return ad.Err()
 }

expr/bitwise_test.go

@@ -0,0 +1,58 @@
+package expr
+
+import (
+	"encoding/binary"
+	"reflect"
+	"testing"
+
+	"github.com/mdlayher/netlink"
+	"golang.org/x/sys/unix"
+)
+
+func TestBitwise(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name string
+		bw   Bitwise
+	}{
+		{
+			name: "Unmarshal Bitwise IPv4 case",
+			bw: Bitwise{
+				SourceRegister: 1,
+				DestRegister:   2,
+				Len:            4,
+				// By specifying Xor to 0x0,0x0,0x0,0x0 and Mask to 0xff,0xff,0x0,0x0
+				// an expression will match /16 IPv4 address.
+				Xor:  []byte{0x0, 0x0, 0x0, 0x0},
+				Mask: []byte{0xff, 0xff, 0x0, 0x0},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			nbw := Bitwise{}
+			data, err := tt.bw.marshal()
+			if err != nil {
+				t.Fatalf("marshal error: %+v", err)
+
+			}
+			ad, err := netlink.NewAttributeDecoder(data)
+			if err != nil {
+				t.Fatalf("NewAttributeDecoder() error: %+v", err)
+			}
+			ad.ByteOrder = binary.BigEndian
+			for ad.Next() {
+				if ad.Type() == unix.NFTA_EXPR_DATA {
+					if err := nbw.unmarshal(ad.Bytes()); err != nil {
+						t.Errorf("unmarshal error: %+v", err)
+						break
+					}
+				}
+			}
+			if !reflect.DeepEqual(tt.bw, nbw) {
+				t.Fatalf("original %+v and recovered %+v Bitwise structs are different", tt.bw, nbw)
+			}
+		})
+	}
+}

go.mod

@@ -4,7 +4,8 @@ go 1.12
 
 require (
 	github.com/koneu/natend v0.0.0-20150829182554-ec0926ea948d
-	github.com/mdlayher/netlink v0.0.0-20190516121005-0087c778e469
+	github.com/mdlayher/netlink v0.0.0-20191009155606-de872b0d824b
 	github.com/vishvananda/netns v0.0.0-20180720170159-13995c7128cc
-	golang.org/x/sys v0.0.0-20190523142557-0e01d883c5c5
+	golang.org/x/net v0.0.0-20191028085509-fe3aa8a45271 // indirect
+	golang.org/x/sys v0.0.0-20191029155521-f43be2a4598c
 )

go.sum

@@ -1,16 +1,26 @@
-github.com/google/go-cmp v0.3.0 h1:crn/baboCvb5fXaQ0IJ1SGTsTVrWpDsCWC8EGETZijY=
+github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
-github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
+github.com/google/go-cmp v0.3.1 h1:Xye71clBPdm5HgqGwUkwhbynsUJZhDbS20FvLhQ2izg=
+github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
+github.com/jsimonetti/rtnetlink v0.0.0-20190606172950-9527aa82566a h1:84IpUNXj4mCR9CuCEvSiCArMbzr/TMbuPIadKDwypkI=
+github.com/jsimonetti/rtnetlink v0.0.0-20190606172950-9527aa82566a/go.mod h1:Oz+70psSo5OFh8DBl0Zv2ACw7Esh6pPUphlvZG9x7uw=
 github.com/koneu/natend v0.0.0-20150829182554-ec0926ea948d h1:MFX8DxRnKMY/2M3H61iSsVbo/n3h0MWGmWNN1UViOU0=
 github.com/koneu/natend v0.0.0-20150829182554-ec0926ea948d/go.mod h1:QHb4k4cr1fQikUahfcRVPcEXiUgFsdIstGqlurL0XL4=
-github.com/mdlayher/netlink v0.0.0-20190516121005-0087c778e469 h1:6XwSkpIirmRxmstYmbL5PshChpqazkNfFNJ+Uj1iJlU=
+github.com/mdlayher/netlink v0.0.0-20190409211403-11939a169225/go.mod h1:eQB3mZE4aiYnlUsyGGCOpPETfdQq4Jhsgf1fk3cwQaA=
-github.com/mdlayher/netlink v0.0.0-20190516121005-0087c778e469/go.mod h1:gOrA34zDL0K3RsACQe54bDYLF/CeFspQ9m5DOycycQ8=
+github.com/mdlayher/netlink v0.0.0-20191009155606-de872b0d824b h1:W3er9pI7mt2gOqOWzwvx20iJ8Akiqz1mUMTxU6wdvl8=
+github.com/mdlayher/netlink v0.0.0-20191009155606-de872b0d824b/go.mod h1:KxeJAFOFLG6AjpyDkQ/iIhxygIUKD+vcwqcnu43w/+M=
 github.com/vishvananda/netns v0.0.0-20180720170159-13995c7128cc h1:R83G5ikgLMxrBvLh22JhdfI8K6YXEPHx5P03Uu3DRs4=
 github.com/vishvananda/netns v0.0.0-20180720170159-13995c7128cc/go.mod h1:ZjcWmFBXmLKZu9Nxj3WKYEafiSqer2rnvPr0en9UNpI=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/net v0.0.0-20190509222800-a4d6f7feada5 h1:6M3SDHlHHDCx2PcQw3S4KsR170vGqDhJDOmpVd4Hjak=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190509222800-a4d6f7feada5/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190827160401-ba9fcec4b297 h1:k7pJ2yAPLPgbskkFdhRCsA77k2fySZ1zf2zCjvQCiIM=
+golang.org/x/net v0.0.0-20190827160401-ba9fcec4b297/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20191028085509-fe3aa8a45271 h1:N66aaryRB3Ax92gH0v3hp1QYZ3zWWCCUR/j8Ifh45Ss=
+golang.org/x/net v0.0.0-20191028085509-fe3aa8a45271/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190509141414-a5b02f93d862/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190523142557-0e01d883c5c5 h1:sM3evRHxE/1RuMe1FYAL3j7C7fUfIjkbE+NiDAYUF8U=
+golang.org/x/sys v0.0.0-20190411185658-b44545bcd369/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190523142557-0e01d883c5c5/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190826190057-c7b8b68b1456 h1:ng0gs1AKnRRuEMZoTLLlbOd+C17zUDepwGQBb/n+JVg=
+golang.org/x/sys v0.0.0-20190826190057-c7b8b68b1456/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191029155521-f43be2a4598c h1:S/FtSvpNLtFBgjTqcKsRpsa6aVsI6iztaz1bQd9BJwE=
+golang.org/x/sys v0.0.0-20191029155521-f43be2a4598c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

rule.go

@@ -190,6 +190,8 @@ func exprsFromMsg(b []byte) ([]expr.Any, error) {
 						e = &expr.Lookup{}
 					case "immediate":
 						e = &expr.Immediate{}
+					case "bitwise":
+						e = &expr.Bitwise{}
 					}
 					if e == nil {
 						// TODO: introduce an opaque expression type so that users know