nftables: Changing HostToNet/NetToHost implementaion.

The previous implementation used the functions in reversed order.

They still worked as the overall effect was same.

Also, changed buffer allocation from `make` to static allocation.

Added some unit tests.

PiperOrigin-RevId: 826228154

Author: parth-opensrc

pkg/sentry/socket/netlink/nlmsg/message.go

@@ -410,49 +410,49 @@ func (v *BytesView) Int32() (int32, bool) {
 // NetToHostU16 converts a uint16 in network byte order to
 // host byte order value.
 func NetToHostU16(v uint16) uint16 {
-	b := make([]byte, 2)
-	binary.NativeEndian.PutUint16(b, v)
-	return binary.BigEndian.Uint16(b)
+	var b [2]byte
+	binary.BigEndian.PutUint16(b[:], v)
+	return binary.NativeEndian.Uint16(b[:])
 }
 
 // NetToHostU32 converts a uint32 in network byte order to
 // host byte order value.
 func NetToHostU32(v uint32) uint32 {
-	b := make([]byte, 4)
-	binary.NativeEndian.PutUint32(b, v)
-	return binary.BigEndian.Uint32(b)
+	var b [4]byte
+	binary.BigEndian.PutUint32(b[:], v)
+	return binary.NativeEndian.Uint32(b[:])
 }
 
 // NetToHostU64 converts a uint64 in network byte order to
 // host byte order value.
 func NetToHostU64(v uint64) uint64 {
-	b := make([]byte, 8)
-	binary.NativeEndian.PutUint64(b, v)
-	return binary.BigEndian.Uint64(b)
+	var b [8]byte
+	binary.BigEndian.PutUint64(b[:], v)
+	return binary.NativeEndian.Uint64(b[:])
 }
 
 // HostToNetU16 converts a uint16 in host byte order to
 // network byte order value.
 func HostToNetU16(v uint16) uint16 {
-	b := make([]byte, 2)
-	binary.BigEndian.PutUint16(b, v)
-	return binary.NativeEndian.Uint16(b)
+	var b [2]byte
+	binary.NativeEndian.PutUint16(b[:], v)
+	return binary.BigEndian.Uint16(b[:])
 }
 
 // HostToNetU32 converts a uint32 in host byte order to
 // network byte order value.
 func HostToNetU32(v uint32) uint32 {
-	b := make([]byte, 4)
-	binary.BigEndian.PutUint32(b, v)
-	return binary.NativeEndian.Uint32(b)
+	var b [4]byte
+	binary.NativeEndian.PutUint32(b[:], v)
+	return binary.BigEndian.Uint32(b[:])
 }
 
 // HostToNetU64 converts a uint64 in host byte order to
 // network byte order value.
 func HostToNetU64(v uint64) uint64 {
-	b := make([]byte, 8)
-	binary.BigEndian.PutUint64(b, v)
-	return binary.NativeEndian.Uint64(b)
+	var b [8]byte
+	binary.NativeEndian.PutUint64(b[:], v)
+	return binary.BigEndian.Uint64(b[:])
 }
 
 // PutU16 converts a uint16 to network byte order and returns it as a

pkg/sentry/socket/netlink/nlmsg/message_test.go

@@ -16,6 +16,7 @@ package message_test
 
 import (
 	"bytes"
+	"fmt"
 	"reflect"
 	"testing"
 
@@ -373,3 +374,93 @@ func TestBytesView(t *testing.T) {
 		}
 	}
 }
+
+func TestHostToNet(t *testing.T) {
+	tests := []struct {
+		name     string
+		validate func() error
+	}{
+		{
+			name: "U16",
+			validate: func() error {
+				v := uint16(0x1234)
+				if got, want := nlmsg.HostToNetU16(v), uint16(0x3412); got != want {
+					return fmt.Errorf("HostToNetU16(0x%x) = 0x%x, want: 0x%x", v, got, want)
+				}
+				return nil
+			},
+		},
+		{
+			name: "U32",
+			validate: func() error {
+				v := uint32(0x12345678)
+				if got, want := nlmsg.HostToNetU32(v), uint32(0x78563412); got != want {
+					return fmt.Errorf("HostToNetU32(0x%x) = 0x%x, want: 0x%x", v, got, want)
+				}
+				return nil
+			},
+		},
+		{
+			name: "U64",
+			validate: func() error {
+				v := uint64(0x123456789abcdef)
+				if got, want := nlmsg.HostToNetU64(v), uint64(0xefcdab8967452301); got != want {
+					return fmt.Errorf("HostToNetU64(0x%x) = 0x%x, want: 0x%x", v, got, want)
+				}
+				return nil
+			},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if err := test.validate(); err != nil {
+				t.Error(err)
+			}
+		})
+	}
+}
+
+func TestNetToHost(t *testing.T) {
+	tests := []struct {
+		name     string
+		validate func() error
+	}{
+		{
+			name: "U16",
+			validate: func() error {
+				v := uint16(0x1234)
+				if got, want := nlmsg.NetToHostU16(v), uint16(0x3412); got != want {
+					return fmt.Errorf("NetToHostU16(0x%x) = 0x%x, want: 0x%x", v, got, want)
+				}
+				return nil
+			},
+		},
+		{
+			name: "U32",
+			validate: func() error {
+				v := uint32(0x12345678)
+				if got, want := nlmsg.NetToHostU32(v), uint32(0x78563412); got != want {
+					return fmt.Errorf("NetToHostU32(0x%x) = 0x%x, want: 0x%x", v, got, want)
+				}
+				return nil
+			},
+		},
+		{
+			name: "U64",
+			validate: func() error {
+				v := uint64(0x123456789abcdef)
+				if got, want := nlmsg.NetToHostU64(v), uint64(0xefcdab8967452301); got != want {
+					return fmt.Errorf("NetToHostU64(0x%x) = 0x%x, want: 0x%x", v, got, want)
+				}
+				return nil
+			},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if err := test.validate(); err != nil {
+				t.Error(err)
+			}
+		})
+	}
+}