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