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tap.go
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tap.go
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// Package phys implements a reader/writer object for reading and writing IPX
// packets from a TAP device.
package phys
import (
"time"
"github.com/google/gopacket"
"github.com/songgao/packets/ethernet"
"github.com/songgao/water"
)
var (
_ = (DuplexEthernetStream)(&tapWrapper{})
)
// tapWrapper implements the DuplexEthernetStream interface by wrapping a
// water.Interface.
type tapWrapper struct {
ifce *water.Interface
}
func (w *tapWrapper) ReadPacketData() ([]byte, gopacket.CaptureInfo, error) {
var frame ethernet.Frame
frame.Resize(1500)
n, err := w.ifce.Read([]byte(frame))
if err != nil {
return nil, gopacket.CaptureInfo{}, err
}
frame = frame[:n]
ci := gopacket.CaptureInfo{
Timestamp: time.Now(),
CaptureLength: n,
Length: n,
}
return frame, ci, nil
}
func (w *tapWrapper) WritePacketData(frame []byte) error {
_, err := w.ifce.Write(frame)
return err
}
func (w *tapWrapper) Close() {
w.ifce.Close()
}
// NewTap creates a new physical IPX interface using a kernel TAP interface.
func NewTap(cfg water.Config) (*tapWrapper, error) {
cfg.DeviceType = water.TAP
ifce, err := water.New(cfg)
if err != nil {
return nil, err
}
return &tapWrapper{ifce}, nil
}