136 lines
2.4 KiB
Go
136 lines
2.4 KiB
Go
package bngsdk
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import (
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"errors"
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"log/slog"
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"net"
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"sync"
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"time"
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"unsafe"
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)
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// ErrReaderDisabled = errors.New("reader is currently turned off")
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var (
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ErrNoData = errors.New("no new data available")
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readTimeout = (time.Second / 60) * 5 // N missed frames at 60fps
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packetPool = sync.Pool{
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New: func() any {
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var b packetBuffer
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return &b
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},
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}
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)
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type packetBuffer [unsafe.Sizeof(Outgauge{})]byte
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type frame struct {
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Buf *packetBuffer
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Len int
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}
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type UDPTransport struct {
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address *net.UDPAddr
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connection *net.UDPConn
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dataChan chan frame
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}
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func NewUDPReader(ip string, port int) (*UDPTransport, error) {
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// Define the IP address and port to listen on
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addr := &net.UDPAddr{
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IP: net.ParseIP(ip),
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Port: port,
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}
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conn, err := net.ListenUDP("udp", addr)
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if err != nil {
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return nil, err
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}
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udpT := UDPTransport{
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address: addr,
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connection: conn,
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dataChan: make(chan frame, 1),
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}
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go udpT.udpSink()
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return &udpT, nil
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}
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func NewUDPWriter(ip string, port int) (*UDPTransport, error) {
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// Define the IP address and port to listen on
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addr := &net.UDPAddr{
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IP: net.ParseIP(ip),
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Port: port,
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}
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conn, err := net.DialUDP("udp", nil, addr)
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if err != nil {
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return nil, err
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}
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return &UDPTransport{
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address: addr,
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connection: conn,
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}, nil
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}
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// udpSink is a loop that will consume the most recent packets on the port
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// instead of letting them pile up
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func (ut *UDPTransport) udpSink() {
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defer close(ut.dataChan)
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for {
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ut.connection.SetReadDeadline(time.Now().Add(readTimeout))
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bufPtr := packetPool.Get().(*packetBuffer)
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nBytes, _, err := ut.connection.ReadFromUDP(bufPtr[:])
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if err != nil {
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return
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}
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frame := frame{
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Buf: bufPtr,
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Len: nBytes,
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}
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select {
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case ut.dataChan <- frame:
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// Packet sent successfuly
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default:
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select {
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case oldFrame := <-ut.dataChan:
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packetPool.Put(oldFrame.Buf)
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default:
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}
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ut.dataChan <- frame
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}
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}
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}
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func (ut *UDPTransport) Write(data []byte) (int, error) {
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return ut.connection.Write(data)
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}
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func (ut *UDPTransport) Read(buffer []byte) (int, error) {
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latestFrame, ok := <-ut.dataChan
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if !ok {
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slog.Error(ErrNoData.Error())
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return 0, ErrNoData
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}
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nBytes := copy(buffer, latestFrame.Buf[:latestFrame.Len])
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packetPool.Put(latestFrame.Buf)
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return nBytes, nil
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}
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func (ut *UDPTransport) Close() error {
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if ut.connection != nil {
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return ut.connection.Close()
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}
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return nil
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}
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