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node_exporter/vendor/github.com/mdlayher/genetlink/message.go

66 lines
1.6 KiB

package genetlink
import (
"errors"
)
var (
// errInvalidMessage is returned when a Message is malformed.
errInvalidMessage = errors.New("generic netlink message is invalid or too short")
)
// A Header is a generic netlink header. A Header is sent and received with
// each generic netlink message to indicate metadata regarding a Message.
type Header struct {
// Command specifies a command to issue to netlink.
Command uint8
// Version specifies the version of a command to use.
Version uint8
}
// headerLen is the length of a Header.
const headerLen = 4 // unix.GENL_HDRLEN
// A Message is a generic netlink message. It contains a Header and an
// arbitrary byte payload, which may be decoded using information from the
// Header.
//
// Data is encoded using the native endianness of the host system. Use
// the netlink.Uint* and netlink.PutUint* functions to encode and decode
// integers.
type Message struct {
Header Header
Data []byte
}
// MarshalBinary marshals a Message into a byte slice.
func (m Message) MarshalBinary() ([]byte, error) {
b := make([]byte, headerLen)
b[0] = m.Header.Command
b[1] = m.Header.Version
// b[2] and b[3] are padding bytes and set to zero
return append(b, m.Data...), nil
}
// UnmarshalBinary unmarshals the contents of a byte slice into a Message.
func (m *Message) UnmarshalBinary(b []byte) error {
if len(b) < headerLen {
return errInvalidMessage
}
// Don't allow reserved pad bytes to be set
if b[2] != 0 || b[3] != 0 {
return errInvalidMessage
}
m.Header.Command = b[0]
m.Header.Version = b[1]
m.Data = b[4:]
return nil
}