/
packet.go
87 lines (61 loc) · 1.42 KB
/
packet.go
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package main
import (
"io"
"os"
"fmt"
"bytes"
"encoding/binary"
"time"
)
// Packet size in byte
const PACKET_SIZE = 33
type Packet struct {
Payload [24]byte
Slot byte
Time int64
}
func NewPacket(payload []byte, slot byte, time int64) *Packet {
p := &Packet{[24]byte{}, slot, time}
copy(p.Payload[:], payload)
return p
}
// Interface for NewPacketFromReader
type byteReader interface {
io.Reader
io.ByteReader
}
// Try to read a packet from a reader (e.g. a UDP connection)
func NewPacketFromReader(r byteReader) (*Packet, os.Error) {
packet := new(Packet)
payloadBuffer := make([]byte, 24)
n, err := r.Read(payloadBuffer)
if n != 24 {
return nil, os.NewError(fmt.Sprintf("Payload too short: %d", n))
}
if err != nil {
return nil, err
}
copy(packet.Payload[:], payloadBuffer)
packet.Slot, err = r.ReadByte()
if err != nil {
return nil, err
}
err = binary.Read(r, binary.BigEndian, &packet.Time)
if err != nil {
return nil, err
}
return packet, nil
}
func (p *Packet) String() string {
theTime := time.NanosecondsToUTC(p.Time * 1e6)
return fmt.Sprintf("Packet{Payload: %s, Slot: %d, Time: %s}\n",
p.Payload, p.Slot, theTime.Format(time.StampNano))
}
func (p *Packet) SendTo(w io.Writer) (int64, os.Error) {
pbuf := bytes.NewBufferString("")
// Fill output buffer
pbuf.Write(p.Payload[:])
pbuf.WriteByte(p.Slot)
binary.Write(pbuf, binary.BigEndian, p.Time)
return pbuf.WriteTo(w)
}