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package main
import (
"context"
"fmt"
"os"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/buffer"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/link/channel"
"gvisor.dev/gvisor/pkg/tcpip/stack"
wgtun "golang.zx2c4.com/wireguard/tun"
)
type GoTun struct {
events chan wgtun.Event
ch *channel.Endpoint
stack *stack.Stack
ctx context.Context
cancel context.CancelFunc
}
func (tun *GoTun) File() *os.File {
fmt.Println("File")
return nil
}
func (tun *GoTun) Read(buff []byte, offset int) (int, error) {
fmt.Println("Read ", len(buff), offset)
p, ok := tun.ch.ReadContext(tun.ctx)
if ok == false {
fmt.Println("Read error")
return 0, nil // FIXME error
}
vv := p.Pkt.Data
v := vv.ToView()
h := p.Pkt.Header.View()
fmt.Println("Read packet", vv.Size(), len(v), len(h), h)
if len(buff) - offset < len(h) + len(v) {
fmt.Println("Short buffer")
return 0, nil // FIXME error
}
copy(buff[offset:], h)
copy(buff[offset+len(h):], v)
return len(h)+len(v), nil
}
func versionToProtocol(version int) tcpip.NetworkProtocolNumber {
switch version {
case header.IPv4Version: return header.IPv4ProtocolNumber
case header.IPv6Version: return header.IPv6ProtocolNumber
}
return 0
}
func (tun *GoTun) Write(buff []byte, offset int) (int, error) {
size := len(buff) - offset
fmt.Println("Write ", len(buff), offset, size)
if size < 1 {
return 0, nil // FIXME error
}
buffSlice := buff[offset : offset+size]
pkt := tcpip.PacketBuffer{
Data: buffer.NewViewFromBytes(buffSlice).ToVectorisedView(),
}
//version := buff[offset] & 0x0f
protocol := versionToProtocol(header.IPVersion(buffSlice))
netProto := tun.stack.NetworkProtocolInstance(protocol)
if netProto == nil {
fmt.Println("Write not ok")
return 0, nil
}
src, dst := netProto.ParseAddresses(pkt.Data.First())
fmt.Println("Write ", src, dst)
// TODO change destination address
tun.ch.InjectInbound(protocol, pkt) // FIXME detect protocol number
return size, nil
}
func (tun *GoTun) Flush() error {
// TODO: can flushing be implemented by buffering and using sendmmsg?
fmt.Println("Flush")
return nil
}
func (tun *GoTun) MTU() (int, error) {
fmt.Println("MTU")
return 1280, nil
}
func (tun *GoTun) Name() (string, error) {
fmt.Println("Name")
return "foobar", nil
}
func (tun *GoTun) Events() chan wgtun.Event {
fmt.Println("Events")
return tun.events
}
func (tun *GoTun) Close() error {
fmt.Println("Close")
// TODO
// tun.cancel()
return nil
}
func CreateGoTun(s *stack.Stack, ch *channel.Endpoint) (wgtun.Device, error) {
size := 16
ctx, cancel := context.WithCancel(context.Background())
tun := &GoTun{
ch: ch,
events: make(chan wgtun.Event, size),
stack: s,
ctx: ctx,
cancel: cancel,
}
// go func() {
fmt.Println("Post event")
tun.events <- wgtun.EventUp
fmt.Println("Posted event")
// }()
return tun, nil
}
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