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link.go
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link.go
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package rtnetlink
import (
"errors"
"fmt"
"net"
"github.com/jsimonetti/rtnetlink/internal/unix"
"github.com/mdlayher/netlink"
)
var (
// errInvalidLinkMessage is returned when a LinkMessage is malformed.
errInvalidLinkMessage = errors.New("rtnetlink LinkMessage is invalid or too short")
// errInvalidLinkMessageAttr is returned when link attributes are malformed.
errInvalidLinkMessageAttr = errors.New("rtnetlink LinkMessage has a wrong attribute data length")
)
var _ Message = &LinkMessage{}
// A LinkMessage is a route netlink link message.
type LinkMessage struct {
// Always set to AF_UNSPEC (0)
Family uint16
// Device Type
Type uint16
// Unique interface index, using a nonzero value with
// NewLink will instruct the kernel to create a
// device with the given index (kernel 3.7+ required)
Index uint32
// Contains device flags, see netdevice(7)
Flags uint32
// Change Flags, specifies which flags will be affected by the Flags field
Change uint32
// Attributes List
Attributes *LinkAttributes
}
// MarshalBinary marshals a LinkMessage into a byte slice.
func (m *LinkMessage) MarshalBinary() ([]byte, error) {
b := make([]byte, unix.SizeofIfInfomsg)
b[0] = 0 // Family
b[1] = 0 // reserved
nativeEndian.PutUint16(b[2:4], m.Type)
nativeEndian.PutUint32(b[4:8], m.Index)
nativeEndian.PutUint32(b[8:12], m.Flags)
nativeEndian.PutUint32(b[12:16], m.Change)
if m.Attributes != nil {
ae := netlink.NewAttributeEncoder()
ae.ByteOrder = nativeEndian
err := m.Attributes.encode(ae)
if err != nil {
return nil, err
}
a, err := ae.Encode()
if err != nil {
return nil, err
}
return append(b, a...), nil
}
return b, nil
}
// UnmarshalBinary unmarshals the contents of a byte slice into a LinkMessage.
func (m *LinkMessage) UnmarshalBinary(b []byte) error {
l := len(b)
if l < unix.SizeofIfInfomsg {
return errInvalidLinkMessage
}
m.Family = nativeEndian.Uint16(b[0:2])
m.Type = nativeEndian.Uint16(b[2:4])
m.Index = nativeEndian.Uint32(b[4:8])
m.Flags = nativeEndian.Uint32(b[8:12])
m.Change = nativeEndian.Uint32(b[12:16])
if l > unix.SizeofIfInfomsg {
m.Attributes = &LinkAttributes{}
ad, err := netlink.NewAttributeDecoder(b[16:])
if err != nil {
return err
}
ad.ByteOrder = nativeEndian
err = m.Attributes.decode(ad)
if err != nil {
return err
}
}
return nil
}
// rtMessage is an empty method to sattisfy the Message interface.
func (*LinkMessage) rtMessage() {}
// LinkService is used to retrieve rtnetlink family information.
type LinkService struct {
c *Conn
}
// execute executes the request and returns the messages as a LinkMessage slice
func (l *LinkService) execute(m Message, family uint16, flags netlink.HeaderFlags) ([]LinkMessage, error) {
msgs, err := l.c.Execute(m, family, flags)
links := make([]LinkMessage, len(msgs))
for i := range msgs {
links[i] = *msgs[i].(*LinkMessage)
}
return links, err
}
// New creates a new interface using the LinkMessage information.
func (l *LinkService) New(req *LinkMessage) error {
flags := netlink.Request | netlink.Create | netlink.Acknowledge | netlink.Excl
_, err := l.execute(req, unix.RTM_NEWLINK, flags)
return err
}
// Delete removes an interface by index.
func (l *LinkService) Delete(index uint32) error {
req := &LinkMessage{
Index: index,
}
flags := netlink.Request | netlink.Acknowledge
_, err := l.c.Execute(req, unix.RTM_DELLINK, flags)
return err
}
// Get retrieves interface information by index.
func (l *LinkService) Get(index uint32) (LinkMessage, error) {
req := &LinkMessage{
Index: index,
}
flags := netlink.Request | netlink.DumpFiltered
links, err := l.execute(req, unix.RTM_GETLINK, flags)
if len(links) != 1 {
return LinkMessage{}, fmt.Errorf("too many/little matches, expected 1, actual %d", len(links))
}
return links[0], err
}
// Set sets interface attributes according to the LinkMessage information.
//
// ref: https://lwn.net/Articles/236919/
// We explicitly use RTM_NEWLINK to set link attributes instead of
// RTM_SETLINK because:
// - using RTM_SETLINK is actually an old rtnetlink API, not supporting most
// attributes common today
// - using RTM_NEWLINK is the prefered way to create AND update links
// - RTM_NEWLINK is backward compatible to RTM_SETLINK
func (l *LinkService) Set(req *LinkMessage) error {
flags := netlink.Request | netlink.Acknowledge
_, err := l.c.Execute(req, unix.RTM_NEWLINK, flags)
return err
}
func (l *LinkService) list(kind string) ([]LinkMessage, error) {
req := &LinkMessage{}
if kind != "" {
req.Attributes = &LinkAttributes{
Info: &LinkInfo{Kind: kind},
}
}
flags := netlink.Request | netlink.Dump
return l.execute(req, unix.RTM_GETLINK, flags)
}
// ListByKind retrieves all interfaces of a specific kind.
func (l *LinkService) ListByKind(kind string) ([]LinkMessage, error) {
return l.list(kind)
}
// List retrieves all interfaces.
func (l *LinkService) List() ([]LinkMessage, error) {
return l.list("")
}
// LinkAttributes contains all attributes for an interface.
type LinkAttributes struct {
Address net.HardwareAddr // Interface L2 address
Alias *string // Interface alias name
Broadcast net.HardwareAddr // L2 broadcast address
Carrier *uint8 // Current physical link state of the interface.
CarrierChanges *uint32 // Number of times the link has seen a change from UP to DOWN and vice versa
CarrierUpCount *uint32 // Number of times the link has been up
CarrierDownCount *uint32 // Number of times the link has been down
Index *uint32 // System-wide interface unique index identifier
Info *LinkInfo // Detailed Interface Information
LinkMode *uint8 // Interface link mode
MTU uint32 // MTU of the device
Name string // Device name
NetDevGroup *uint32 // Interface network device group
OperationalState OperationalState // Interface operation state
PhysPortID *string // Interface unique physical port identifier within the NIC
PhysPortName *string // Interface physical port name within the NIC
PhysSwitchID *string // Unique physical switch identifier of a switch this port belongs to
QueueDisc string // Queueing discipline
Master *uint32 // Master device index (0 value un-enslaves)
Stats *LinkStats // Interface Statistics
Stats64 *LinkStats64 // Interface Statistics (64 bits version)
TxQueueLen *uint32 // Interface transmit queue len in number of packets
Type uint32 // Link type
XDP *LinkXDP // Express Data Patch Information
}
// OperationalState represents an interface's operational state.
type OperationalState uint8
// Constants that represent operational state of an interface
//
// Adapted from https://elixir.bootlin.com/linux/v4.19.2/source/include/uapi/linux/if.h#L166
const (
OperStateUnknown OperationalState = iota // status could not be determined
OperStateNotPresent // down, due to some missing component (typically hardware)
OperStateDown // down, either administratively or due to a fault
OperStateLowerLayerDown // down, due to lower-layer interfaces
OperStateTesting // operationally down, in some test mode
OperStateDormant // down, waiting for some external event
OperStateUp // interface is in a state to send and receive packets
)
// unmarshalBinary unmarshals the contents of a byte slice into a LinkMessage.
func (a *LinkAttributes) decode(ad *netlink.AttributeDecoder) error {
for ad.Next() {
switch ad.Type() {
case unix.IFLA_UNSPEC:
// unused attribute
case unix.IFLA_ADDRESS:
l := len(ad.Bytes())
if l < 4 || l > 32 {
return errInvalidLinkMessageAttr
}
a.Address = ad.Bytes()
case unix.IFLA_IFALIAS:
v := ad.String()
a.Alias = &v
case unix.IFLA_BROADCAST:
l := len(ad.Bytes())
if l < 4 || l > 32 {
return errInvalidLinkMessageAttr
}
a.Broadcast = ad.Bytes()
case unix.IFLA_CARRIER:
v := ad.Uint8()
a.Carrier = &v
case unix.IFLA_CARRIER_CHANGES:
v := ad.Uint32()
a.CarrierChanges = &v
case unix.IFLA_CARRIER_UP_COUNT:
v := ad.Uint32()
a.CarrierUpCount = &v
case unix.IFLA_CARRIER_DOWN_COUNT:
v := ad.Uint32()
a.CarrierDownCount = &v
case unix.IFLA_GROUP:
v := ad.Uint32()
a.NetDevGroup = &v
case unix.IFLA_MTU:
a.MTU = ad.Uint32()
case unix.IFLA_IFNAME:
a.Name = ad.String()
case unix.IFLA_LINK:
a.Type = ad.Uint32()
case unix.IFLA_LINKINFO:
a.Info = &LinkInfo{}
ad.Nested(a.Info.decode)
case unix.IFLA_LINKMODE:
v := ad.Uint8()
a.LinkMode = &v
case unix.IFLA_MASTER:
v := ad.Uint32()
a.Master = &v
case unix.IFLA_OPERSTATE:
a.OperationalState = OperationalState(ad.Uint8())
case unix.IFLA_PHYS_PORT_ID:
v := ad.String()
a.PhysPortID = &v
case unix.IFLA_PHYS_SWITCH_ID:
v := ad.String()
a.PhysSwitchID = &v
case unix.IFLA_PHYS_PORT_NAME:
v := ad.String()
a.PhysPortName = &v
case unix.IFLA_QDISC:
a.QueueDisc = ad.String()
case unix.IFLA_STATS:
a.Stats = &LinkStats{}
err := a.Stats.unmarshalBinary(ad.Bytes())
if err != nil {
return err
}
case unix.IFLA_STATS64:
a.Stats64 = &LinkStats64{}
err := a.Stats64.unmarshalBinary(ad.Bytes())
if err != nil {
return err
}
case unix.IFLA_TXQLEN:
v := ad.Uint32()
a.TxQueueLen = &v
case unix.IFLA_XDP:
a.XDP = &LinkXDP{}
ad.Nested(a.XDP.decode)
}
}
return nil
}
// MarshalBinary marshals a LinkAttributes into a byte slice.
func (a *LinkAttributes) encode(ae *netlink.AttributeEncoder) error {
ae.Uint16(unix.IFLA_UNSPEC, 0)
ae.String(unix.IFLA_IFNAME, a.Name)
ae.Uint32(unix.IFLA_LINK, a.Type)
ae.String(unix.IFLA_QDISC, a.QueueDisc)
if a.MTU != 0 {
ae.Uint32(unix.IFLA_MTU, a.MTU)
}
if len(a.Address) != 0 {
ae.Bytes(unix.IFLA_ADDRESS, a.Address)
}
if len(a.Broadcast) != 0 {
ae.Bytes(unix.IFLA_BROADCAST, a.Broadcast)
}
if a.OperationalState != OperStateUnknown {
ae.Uint8(unix.IFLA_OPERSTATE, uint8(a.OperationalState))
}
if a.Info != nil {
nae := netlink.NewAttributeEncoder()
nae.ByteOrder = ae.ByteOrder
err := a.Info.encode(nae)
if err != nil {
return err
}
b, err := nae.Encode()
if err != nil {
return err
}
ae.Bytes(unix.IFLA_LINKINFO, b)
}
if a.XDP != nil {
nae := netlink.NewAttributeEncoder()
nae.ByteOrder = ae.ByteOrder
err := a.XDP.encode(nae)
if err != nil {
return err
}
b, err := nae.Encode()
if err != nil {
return err
}
ae.Bytes(unix.IFLA_XDP, b)
}
if a.Master != nil {
ae.Uint32(unix.IFLA_MASTER, *a.Master)
}
return nil
}
// LinkStats contains packet statistics
type LinkStats struct {
RXPackets uint32 // total packets received
TXPackets uint32 // total packets transmitted
RXBytes uint32 // total bytes received
TXBytes uint32 // total bytes transmitted
RXErrors uint32 // bad packets received
TXErrors uint32 // packet transmit problems
RXDropped uint32 // no space in linux buffers
TXDropped uint32 // no space available in linux
Multicast uint32 // multicast packets received
Collisions uint32
// detailed rx_errors:
RXLengthErrors uint32
RXOverErrors uint32 // receiver ring buff overflow
RXCRCErrors uint32 // recved pkt with crc error
RXFrameErrors uint32 // recv'd frame alignment error
RXFIFOErrors uint32 // recv'r fifo overrun
RXMissedErrors uint32 // receiver missed packet
// detailed tx_errors
TXAbortedErrors uint32
TXCarrierErrors uint32
TXFIFOErrors uint32
TXHeartbeatErrors uint32
TXWindowErrors uint32
// for cslip etc
RXCompressed uint32
TXCompressed uint32
RXNoHandler uint32 // dropped, no handler found
}
// unmarshalBinary unmarshals the contents of a byte slice into a LinkMessage.
func (a *LinkStats) unmarshalBinary(b []byte) error {
l := len(b)
if l != 92 && l != 96 {
return fmt.Errorf("incorrect LinkMessage size, want: 92 or 96, got: %d", len(b))
}
a.RXPackets = nativeEndian.Uint32(b[0:4])
a.TXPackets = nativeEndian.Uint32(b[4:8])
a.RXBytes = nativeEndian.Uint32(b[8:12])
a.TXBytes = nativeEndian.Uint32(b[12:16])
a.RXErrors = nativeEndian.Uint32(b[16:20])
a.TXErrors = nativeEndian.Uint32(b[20:24])
a.RXDropped = nativeEndian.Uint32(b[24:28])
a.TXDropped = nativeEndian.Uint32(b[28:32])
a.Multicast = nativeEndian.Uint32(b[32:36])
a.Collisions = nativeEndian.Uint32(b[36:40])
a.RXLengthErrors = nativeEndian.Uint32(b[40:44])
a.RXOverErrors = nativeEndian.Uint32(b[44:48])
a.RXCRCErrors = nativeEndian.Uint32(b[48:52])
a.RXFrameErrors = nativeEndian.Uint32(b[52:56])
a.RXFIFOErrors = nativeEndian.Uint32(b[56:60])
a.RXMissedErrors = nativeEndian.Uint32(b[60:64])
a.TXAbortedErrors = nativeEndian.Uint32(b[64:68])
a.TXCarrierErrors = nativeEndian.Uint32(b[68:72])
a.TXFIFOErrors = nativeEndian.Uint32(b[72:76])
a.TXHeartbeatErrors = nativeEndian.Uint32(b[76:80])
a.TXWindowErrors = nativeEndian.Uint32(b[80:84])
a.RXCompressed = nativeEndian.Uint32(b[84:88])
a.TXCompressed = nativeEndian.Uint32(b[88:92])
if l == 96 { // kernel 4.6+
a.RXNoHandler = nativeEndian.Uint32(b[92:96])
}
return nil
}
// LinkStats64 contains packet statistics
type LinkStats64 struct {
RXPackets uint64 // total packets received
TXPackets uint64 // total packets transmitted
RXBytes uint64 // total bytes received
TXBytes uint64 // total bytes transmitted
RXErrors uint64 // bad packets received
TXErrors uint64 // packet transmit problems
RXDropped uint64 // no space in linux buffers
TXDropped uint64 // no space available in linux
Multicast uint64 // multicast packets received
Collisions uint64
// detailed rx_errors:
RXLengthErrors uint64
RXOverErrors uint64 // receiver ring buff overflow
RXCRCErrors uint64 // recved pkt with crc error
RXFrameErrors uint64 // recv'd frame alignment error
RXFIFOErrors uint64 // recv'r fifo overrun
RXMissedErrors uint64 // receiver missed packet
// detailed tx_errors
TXAbortedErrors uint64
TXCarrierErrors uint64
TXFIFOErrors uint64
TXHeartbeatErrors uint64
TXWindowErrors uint64
// for cslip etc
RXCompressed uint64
TXCompressed uint64
RXNoHandler uint64 // dropped, no handler found
RXOtherhostDropped uint64 // Number of packets dropped due to mismatch in destination MAC address.
}
// unmarshalBinary unmarshals the contents of a byte slice into a LinkMessage.
func (a *LinkStats64) unmarshalBinary(b []byte) error {
l := len(b)
if l != 184 && l != 192 && l != 200 {
return fmt.Errorf("incorrect size, want: 184 or 192 or 200")
}
a.RXPackets = nativeEndian.Uint64(b[0:8])
a.TXPackets = nativeEndian.Uint64(b[8:16])
a.RXBytes = nativeEndian.Uint64(b[16:24])
a.TXBytes = nativeEndian.Uint64(b[24:32])
a.RXErrors = nativeEndian.Uint64(b[32:40])
a.TXErrors = nativeEndian.Uint64(b[40:48])
a.RXDropped = nativeEndian.Uint64(b[48:56])
a.TXDropped = nativeEndian.Uint64(b[56:64])
a.Multicast = nativeEndian.Uint64(b[64:72])
a.Collisions = nativeEndian.Uint64(b[72:80])
a.RXLengthErrors = nativeEndian.Uint64(b[80:88])
a.RXOverErrors = nativeEndian.Uint64(b[88:96])
a.RXCRCErrors = nativeEndian.Uint64(b[96:104])
a.RXFrameErrors = nativeEndian.Uint64(b[104:112])
a.RXFIFOErrors = nativeEndian.Uint64(b[112:120])
a.RXMissedErrors = nativeEndian.Uint64(b[120:128])
a.TXAbortedErrors = nativeEndian.Uint64(b[128:136])
a.TXCarrierErrors = nativeEndian.Uint64(b[136:144])
a.TXFIFOErrors = nativeEndian.Uint64(b[144:152])
a.TXHeartbeatErrors = nativeEndian.Uint64(b[152:160])
a.TXWindowErrors = nativeEndian.Uint64(b[160:168])
a.RXCompressed = nativeEndian.Uint64(b[168:176])
a.TXCompressed = nativeEndian.Uint64(b[176:184])
if l > 191 { // kernel 4.6+
a.RXNoHandler = nativeEndian.Uint64(b[184:192])
}
if l > 199 { // kernel 5.19+
a.RXOtherhostDropped = nativeEndian.Uint64(b[192:200])
}
return nil
}
// LinkInfo contains data for specific network types
type LinkInfo struct {
Kind string // Driver name
Data []byte // Driver specific configuration stored as nested Netlink messages
SlaveKind string // Slave driver name
SlaveData []byte // Slave driver specific configuration
}
func (i *LinkInfo) decode(ad *netlink.AttributeDecoder) error {
for ad.Next() {
switch ad.Type() {
case unix.IFLA_INFO_KIND:
i.Kind = ad.String()
case unix.IFLA_INFO_SLAVE_KIND:
i.SlaveKind = ad.String()
case unix.IFLA_INFO_DATA:
i.Data = ad.Bytes()
case unix.IFLA_INFO_SLAVE_DATA:
i.SlaveData = ad.Bytes()
}
}
return nil
}
func (i *LinkInfo) encode(ae *netlink.AttributeEncoder) error {
ae.String(unix.IFLA_INFO_KIND, i.Kind)
ae.Bytes(unix.IFLA_INFO_DATA, i.Data)
if len(i.SlaveData) > 0 {
ae.String(unix.IFLA_INFO_SLAVE_KIND, i.SlaveKind)
ae.Bytes(unix.IFLA_INFO_SLAVE_DATA, i.SlaveData)
}
return nil
}
// LinkXDP holds Express Data Path specific information
type LinkXDP struct {
FD int32
ExpectedFD int32
Attached uint8
Flags uint32
ProgID uint32
}
func (xdp *LinkXDP) decode(ad *netlink.AttributeDecoder) error {
for ad.Next() {
switch ad.Type() {
case unix.IFLA_XDP_FD:
xdp.FD = ad.Int32()
case unix.IFLA_XDP_EXPECTED_FD:
xdp.ExpectedFD = ad.Int32()
case unix.IFLA_XDP_ATTACHED:
xdp.Attached = ad.Uint8()
case unix.IFLA_XDP_FLAGS:
xdp.Flags = ad.Uint32()
case unix.IFLA_XDP_PROG_ID:
xdp.ProgID = ad.Uint32()
}
}
return nil
}
func (xdp *LinkXDP) encode(ae *netlink.AttributeEncoder) error {
ae.Int32(unix.IFLA_XDP_FD, xdp.FD)
ae.Int32(unix.IFLA_XDP_EXPECTED_FD, xdp.ExpectedFD)
ae.Uint32(unix.IFLA_XDP_FLAGS, xdp.Flags)
// XDP_ATtACHED and XDP_PROG_ID are things that only can return from the kernel,
// not be send, so we don't encode them.
// source: https://elixir.bootlin.com/linux/v5.10.15/source/net/core/rtnetlink.c#L2894
return nil
}