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driver: fix VLAN protocol byte order on big-endian systems #334

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4 changes: 2 additions & 2 deletions driver/bridge.go
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Original file line number Diff line number Diff line change
Expand Up @@ -190,7 +190,7 @@ func (b *Bridge) Encode(ae *netlink.AttributeEncoder) error {
ae.Uint8(unix.IFLA_BR_VLAN_FILTERING, uint8(*b.VlanFiltering))
}
if b.VlanProtocol != nil {
ae.Uint16(unix.IFLA_BR_VLAN_PROTOCOL, uint16(*b.VlanProtocol))
b.VlanProtocol.encode(ae, unix.IFLA_BR_VLAN_PROTOCOL)
}
if b.GroupFwdMask != nil {
ae.Uint16(unix.IFLA_BR_GROUP_FWD_MASK, *b.GroupFwdMask)
Expand Down Expand Up @@ -302,7 +302,7 @@ func (b *Bridge) Decode(ad *netlink.AttributeDecoder) error {
v := BridgeEnable(ad.Uint8())
b.VlanFiltering = &v
case unix.IFLA_BR_VLAN_PROTOCOL:
v := VlanProtocol(ad.Uint16())
v := decodeVlanProtocol(ad)
b.VlanProtocol = &v
case unix.IFLA_BR_GROUP_FWD_MASK:
v := ad.Uint16()
Expand Down
38 changes: 16 additions & 22 deletions driver/bridge_test.go
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
package driver

import (
"encoding/binary"
"net"
"testing"

Expand Down Expand Up @@ -188,23 +189,14 @@ func TestBridgeDecodeRaw(t *testing.T) {
}{
{
name: "STP state",
b: []byte{
0x08, 0x00, // Length: 8
unix.IFLA_BR_STP_STATE, 0x00, // Type: IFLA_BR_STP_STATE
0x01, 0x00, 0x00, 0x00, // Value: 1
},
b: rawBridgeAttribute(unix.IFLA_BR_STP_STATE, binary.NativeEndian.AppendUint32(nil, 1)),
want: &Bridge{
StpState: ptr(BridgeStpStateEnabled),
},
},
{
name: "VLAN filtering",
b: []byte{
0x05, 0x00, // Length: 5
unix.IFLA_BR_VLAN_FILTERING, 0x00, // Type: IFLA_BR_VLAN_FILTERING
0x01, // Value: 1
0x00, 0x00, 0x00, // Padding
},
b: rawBridgeAttribute(unix.IFLA_BR_VLAN_FILTERING, []byte{1}),
want: &Bridge{
VlanFiltering: ptr(BridgeEnableEnabled),
},
Expand Down Expand Up @@ -383,23 +375,14 @@ func TestBridgePortDecodeRaw(t *testing.T) {
}{
{
name: "port state",
b: []byte{
0x05, 0x00, // Length: 5
unix.IFLA_BRPORT_STATE, 0x00, // Type: IFLA_BRPORT_STATE
0x03, // Value: 3 (forwarding)
0x00, 0x00, 0x00, // Padding
},
b: rawBridgeAttribute(unix.IFLA_BRPORT_STATE, []byte{3}),
want: &BridgePort{
State: ptr(BridgePortStateForwarding),
},
},
{
name: "port cost",
b: []byte{
0x08, 0x00, // Length: 8
unix.IFLA_BRPORT_COST, 0x00, // Type: IFLA_BRPORT_COST
0x64, 0x00, 0x00, 0x00, // Value: 100
},
b: rawBridgeAttribute(unix.IFLA_BRPORT_COST, binary.NativeEndian.AppendUint32(nil, 100)),
want: &BridgePort{
Cost: ptr(uint32(100)),
},
Expand Down Expand Up @@ -429,3 +412,14 @@ func TestBridgePortDecodeRaw(t *testing.T) {
func ptr[T any](t T) *T {
return &t
}

// rawBridgeAttribute builds a native-endian netlink header around a raw payload.
func rawBridgeAttribute(typ uint16, payload []byte) []byte {
b := binary.NativeEndian.AppendUint16(nil, uint16(4+len(payload)))
b = binary.NativeEndian.AppendUint16(b, typ)
b = append(b, payload...)
for len(b)%4 != 0 {
b = append(b, 0)
}
return b
}
26 changes: 22 additions & 4 deletions driver/vlan.go
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
package driver

import (
"encoding/binary"
"fmt"

"github.com/jsimonetti/rtnetlink/v2"
Expand All @@ -15,10 +16,10 @@ type VlanProtocol uint16
// VLAN protocols.
const (
// VlanProtocol8021Q represents 802.1Q VLAN tagging (standard VLAN).
VlanProtocol8021Q VlanProtocol = 0x0081
VlanProtocol8021Q VlanProtocol = 0x8100

// VlanProtocol8021AD represents 802.1ad QinQ (VLAN stacking).
VlanProtocol8021AD VlanProtocol = 0xA888
VlanProtocol8021AD VlanProtocol = 0x88A8
)

// String returns a string representation of the VlanProtocol.
Expand All @@ -33,6 +34,23 @@ func (p VlanProtocol) String() string {
}
}

// VLAN protocol payloads use network byte order even though the surrounding
// attributes use native byte order.
func (p VlanProtocol) encode(ae *netlink.AttributeEncoder, typ uint16) {
order := ae.ByteOrder
ae.ByteOrder = binary.BigEndian
ae.Uint16(typ, uint16(p))
ae.ByteOrder = order
}

func decodeVlanProtocol(ad *netlink.AttributeDecoder) VlanProtocol {
order := ad.ByteOrder
ad.ByteOrder = binary.BigEndian
protocol := VlanProtocol(ad.Uint16())
ad.ByteOrder = order
return protocol
}

// VlanFlag represents VLAN flags.
type VlanFlag uint32

Expand Down Expand Up @@ -88,7 +106,7 @@ func (v *Vlan) Encode(ae *netlink.AttributeEncoder) error {
}

if v.Protocol != nil {
ae.Uint16(unix.IFLA_VLAN_PROTOCOL, uint16(*v.Protocol))
v.Protocol.encode(ae, unix.IFLA_VLAN_PROTOCOL)
}

if v.Flags != nil {
Expand Down Expand Up @@ -138,7 +156,7 @@ func (v *Vlan) Decode(ad *netlink.AttributeDecoder) error {
v.ID = &id

case unix.IFLA_VLAN_PROTOCOL:
protocol := VlanProtocol(ad.Uint16())
protocol := decodeVlanProtocol(ad)
v.Protocol = &protocol

case unix.IFLA_VLAN_FLAGS:
Expand Down
92 changes: 92 additions & 0 deletions driver/vlan_protocol_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,92 @@
package driver

import (
"bytes"
"encoding/binary"
"testing"

"github.com/jsimonetti/rtnetlink/v2"
"github.com/jsimonetti/rtnetlink/v2/internal/unix"
"github.com/mdlayher/netlink"
)

func TestVlanProtocolNetworkOrder(t *testing.T) {
for _, protocol := range []struct {
name string
value VlanProtocol
wire []byte
}{
{"802.1Q", VlanProtocol8021Q, []byte{0x81, 0x00}},
{"802.1ad", VlanProtocol8021AD, []byte{0x88, 0xa8}},
} {
for _, order := range []binary.ByteOrder{binary.LittleEndian, binary.BigEndian} {
for _, driver := range []struct {
name string
new func() rtnetlink.LinkDriver
configured rtnetlink.LinkDriver
protocolType uint16
nativeType uint16
}{
{"vlan", func() rtnetlink.LinkDriver { return &Vlan{} }, &Vlan{Protocol: &protocol.value}, unix.IFLA_VLAN_PROTOCOL, unix.IFLA_VLAN_ID},
{"bridge", func() rtnetlink.LinkDriver { return &Bridge{} }, &Bridge{VlanProtocol: &protocol.value}, unix.IFLA_BR_VLAN_PROTOCOL, unix.IFLA_BR_GROUP_FWD_MASK},
} {
t.Run(protocol.name+"/"+order.String()+"/"+driver.name, func(t *testing.T) {
ae := netlink.NewAttributeEncoder()
ae.ByteOrder = order
if err := driver.configured.Encode(ae); err != nil {
t.Fatal(err)
}
// Protocol byte order must not change later native-endian attributes.
ae.Uint16(driver.nativeType, 0x1234)
b, err := ae.Encode()
if err != nil {
t.Fatal(err)
}
attrs, err := netlink.UnmarshalAttributes(b)
if err != nil {
t.Fatal(err)
}
if !bytes.Equal(attrs[0].Data, protocol.wire) {
t.Errorf("protocol payload: got %x, want %x", attrs[0].Data, protocol.wire)
}
if got := order.Uint16(attrs[1].Data); got != 0x1234 {
t.Errorf("native attribute: got %x, want 1234", got)
}

// Decode an independent kernel-format fixture, not the encoder output.
ae = netlink.NewAttributeEncoder()
ae.ByteOrder = order
ae.Bytes(driver.protocolType, protocol.wire)
ae.Uint16(driver.nativeType, 0x1234)
b, err = ae.Encode()
if err != nil {
t.Fatal(err)
}
ad, err := netlink.NewAttributeDecoder(b)
if err != nil {
t.Fatal(err)
}
ad.ByteOrder = order
decoded := driver.new()
if err := decoded.Decode(ad); err != nil {
t.Fatal(err)
}
var gotProtocol *VlanProtocol
var gotNative *uint16
switch d := decoded.(type) {
case *Vlan:
gotProtocol, gotNative = d.Protocol, d.ID
case *Bridge:
gotProtocol, gotNative = d.VlanProtocol, d.GroupFwdMask
}
if gotProtocol == nil || *gotProtocol != protocol.value {
t.Errorf("decoded protocol: got %v, want %v", gotProtocol, protocol.value)
}
if gotNative == nil || *gotNative != 0x1234 {
t.Errorf("decoded native attribute: got %v, want 1234", gotNative)
}
})
}
}
}
}
2 changes: 1 addition & 1 deletion driver/vlan_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -230,7 +230,7 @@ func TestVlanDecodeRaw(t *testing.T) {
data: func() []byte {
ae := netlink.NewAttributeEncoder()
ae.Uint16(unix.IFLA_VLAN_ID, 100)
ae.Uint16(unix.IFLA_VLAN_PROTOCOL, uint16(VlanProtocol8021Q))
ae.Bytes(unix.IFLA_VLAN_PROTOCOL, []byte{0x81, 0x00})
b, _ := ae.Encode()
return b
}(),
Expand Down
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