62 lines
1.6 KiB
Go
62 lines
1.6 KiB
Go
// Copyright 2018 The agentx authors
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// Licensed under the LGPLv3 with static-linking exception.
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// See LICENCE file for details.
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package pdu
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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)
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const (
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// HeaderSize defines the total size of a header packet.
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HeaderSize = 20
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)
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// Header defines a pdu packet header
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type Header struct {
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Version byte
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Type Type
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Flags Flags
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SessionID uint32
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TransactionID uint32
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PacketID uint32
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PayloadLength uint32
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}
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// MarshalBinary returns the pdu header as a slice of bytes.
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func (h *Header) MarshalBinary() ([]byte, error) {
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buffer := bytes.NewBuffer([]byte{h.Version, byte(h.Type), byte(h.Flags), 0x00})
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binary.Write(buffer, binary.LittleEndian, h.SessionID)
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binary.Write(buffer, binary.LittleEndian, h.TransactionID)
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binary.Write(buffer, binary.LittleEndian, h.PacketID)
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binary.Write(buffer, binary.LittleEndian, h.PayloadLength)
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return buffer.Bytes(), nil
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}
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// UnmarshalBinary sets the header structure from the provided slice of bytes.
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func (h *Header) UnmarshalBinary(data []byte) error {
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if len(data) < HeaderSize {
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return fmt.Errorf("not enough bytes (%d) to unmarshal the header (%d)", len(data), HeaderSize)
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}
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h.Version, h.Type, h.Flags = data[0], Type(data[1]), Flags(data[2])
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buffer := bytes.NewBuffer(data[4:])
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binary.Read(buffer, binary.LittleEndian, &h.SessionID)
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binary.Read(buffer, binary.LittleEndian, &h.TransactionID)
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binary.Read(buffer, binary.LittleEndian, &h.PacketID)
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binary.Read(buffer, binary.LittleEndian, &h.PayloadLength)
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return nil
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}
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func (h *Header) String() string {
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return "(header " + h.Type.String() + ")"
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}
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