/
netlink.go
71 lines (60 loc) · 1.69 KB
/
netlink.go
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package netlink
import (
"bytes"
"encoding/binary"
"errors"
"golang.org/x/sys/unix"
)
var ByteOrder = binary.LittleEndian
var NlmsgAlignTo uint32 = 4
var (
NlMsgDoesNotFit = errors.New("nlmsg does not fit into buffer")
NlMsgHeaderError = errors.New("nlmsghdr error")
)
type NetlinkMessage struct {
Header unix.NlMsghdr
Payload []byte
}
// Round the length of a netlink message
func nlmAlignOf(msglen uint32) uint32 {
return (msglen + NlmsgAlignTo - 1) & ^(NlmsgAlignTo - 1)
}
func NewSerializedNetlinkMessage(h unix.NlMsghdr) []byte {
b := make([]byte, h.Len)
ByteOrder.PutUint32(b[:4], h.Len)
ByteOrder.PutUint16(b[4:6], h.Type)
ByteOrder.PutUint16(b[6:8], h.Flags)
ByteOrder.PutUint32(b[8:12], h.Seq)
ByteOrder.PutUint32(b[12:16], h.Pid)
return b
}
func DeserializeNetlinkMsg(data []byte) (*NetlinkMessage, error) {
len := nlmAlignOf(ByteOrder.Uint32(data[:4]))
if !IsOkToParse(data, len) {
return nil, NlMsgDoesNotFit
}
serializedData := bytes.NewBuffer(data[:unix.NLMSG_HDRLEN])
h := unix.NlMsghdr{}
err := binary.Read(serializedData, ByteOrder, &h)
if err != nil {
return nil, err
}
return &NetlinkMessage{Header: h, Payload: data[unix.NLMSG_HDRLEN:len]}, nil
}
func IsOkToParse(data []byte, nlmsglen uint32) bool {
bufLen := uint32(len(data))
return unix.NLMSG_HDRLEN <= bufLen && nlmsglen >= unix.NLMSG_HDRLEN && bufLen >= nlmsglen
}
func ParseNetlinkMessage(data []byte) ([]NetlinkMessage, error) {
nlmsgs := make([]NetlinkMessage, 0)
for len(data) >= unix.NLMSG_HDRLEN {
len := ByteOrder.Uint32(data[:4])
msg, err := DeserializeNetlinkMsg(data[:len])
if err != nil {
return nil, err
}
nlmsgs = append(nlmsgs, *msg)
data = data[len:]
}
return nlmsgs, nil
}