106 lines
2.9 KiB
Go
106 lines
2.9 KiB
Go
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package gameserver
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import (
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"encoding/binary"
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"errors"
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"fmt"
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)
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const (
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HeadMagic uint32 = 0x9D74C714
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TailMagic uint32 = 0xD7A152C8
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)
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// NetPacket is the framed protocol inside the KCP stream.
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type NetPacket struct {
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CmdType uint16
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Head []byte
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Body []byte
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}
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var ErrMalformedPacket = errors.New("malformed packet")
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func (p *NetPacket) Encode() []byte {
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out := make([]byte, 0, 12+len(p.Head)+len(p.Body))
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var be32 [4]byte
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var be16 [2]byte
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binary.BigEndian.PutUint32(be32[:], HeadMagic)
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out = append(out, be32[:]...)
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binary.BigEndian.PutUint16(be16[:], p.CmdType)
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out = append(out, be16[:]...)
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binary.BigEndian.PutUint16(be16[:], uint16(len(p.Head)))
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out = append(out, be16[:]...)
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binary.BigEndian.PutUint32(be32[:], uint32(len(p.Body)))
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out = append(out, be32[:]...)
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out = append(out, p.Head...)
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out = append(out, p.Body...)
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binary.BigEndian.PutUint32(be32[:], TailMagic)
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out = append(out, be32[:]...)
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return out
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}
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// DecodeNetPacket parses one framed packet (must be a complete packet).
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func DecodeNetPacket(data []byte) (*NetPacket, error) {
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if len(data) < 16 {
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return nil, fmt.Errorf("%w: too short (%d)", ErrMalformedPacket, len(data))
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}
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if binary.BigEndian.Uint32(data[0:4]) != HeadMagic {
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return nil, fmt.Errorf("%w: bad head magic", ErrMalformedPacket)
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}
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cmdType := binary.BigEndian.Uint16(data[4:6])
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headLen := int(binary.BigEndian.Uint16(data[6:8]))
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bodyLen := int(binary.BigEndian.Uint32(data[8:12]))
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if len(data) < 12+headLen+bodyLen+4 {
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return nil, fmt.Errorf("%w: truncated", ErrMalformedPacket)
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}
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if binary.BigEndian.Uint32(data[12+headLen+bodyLen:]) != TailMagic {
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return nil, fmt.Errorf("%w: bad tail magic", ErrMalformedPacket)
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}
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return &NetPacket{
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CmdType: cmdType,
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Head: data[12 : 12+headLen],
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Body: data[12+headLen : 12+headLen+bodyLen],
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}, nil
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}
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// NetOperation is the 20-byte handshake control packet.
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type NetOperation struct {
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Head uint32
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Param1 uint32
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Param2 uint32
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Data uint32
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Tail uint32
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}
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const (
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NetOpConnectHead uint32 = 0xFF
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NetOpConnectTail uint32 = 0xFFFFFFFF
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NetOpAcceptHead uint32 = 0x145
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NetOpAcceptTail uint32 = 0x14514545
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NetOpDropHead uint32 = 0x194
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NetOpDropTail uint32 = 0x19419494
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)
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func DecodeNetOperation(data []byte) (*NetOperation, error) {
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if len(data) < 20 {
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return nil, fmt.Errorf("%w: netop too short", ErrMalformedPacket)
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}
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return &NetOperation{
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Head: binary.BigEndian.Uint32(data[0:4]),
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Param1: binary.BigEndian.Uint32(data[4:8]),
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Param2: binary.BigEndian.Uint32(data[8:12]),
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Data: binary.BigEndian.Uint32(data[12:16]),
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Tail: binary.BigEndian.Uint32(data[16:20]),
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}, nil
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}
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func (o *NetOperation) Encode() []byte {
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out := make([]byte, 20)
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binary.BigEndian.PutUint32(out[0:4], o.Head)
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binary.BigEndian.PutUint32(out[4:8], o.Param1)
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binary.BigEndian.PutUint32(out[8:12], o.Param2)
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binary.BigEndian.PutUint32(out[12:16], o.Data)
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binary.BigEndian.PutUint32(out[16:20], o.Tail)
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return out
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}
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