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- // Copyright 2025 The frp Authors
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
- package vnet
- import (
- "context"
- "io"
- "github.com/fatedier/golib/pool"
- "golang.zx2c4.com/wireguard/tun"
- )
- const (
- offset = 16
- defaultPacketSize = 1420
- )
- type TunDevice interface {
- io.ReadWriteCloser
- }
- func OpenTun(ctx context.Context, addr string) (TunDevice, error) {
- td, err := openTun(ctx, addr)
- if err != nil {
- return nil, err
- }
- mtu, err := td.MTU()
- if err != nil {
- mtu = defaultPacketSize
- }
- bufferSize := max(mtu, defaultPacketSize)
- batchSize := td.BatchSize()
- device := &tunDeviceWrapper{
- dev: td,
- bufferSize: bufferSize,
- readBuffers: make([][]byte, batchSize),
- sizeBuffer: make([]int, batchSize),
- }
- for i := range device.readBuffers {
- device.readBuffers[i] = make([]byte, offset+bufferSize)
- }
- return device, nil
- }
- type tunDeviceWrapper struct {
- dev tun.Device
- bufferSize int
- readBuffers [][]byte
- packetBuffers [][]byte
- sizeBuffer []int
- }
- func (d *tunDeviceWrapper) Read(p []byte) (int, error) {
- if len(d.packetBuffers) > 0 {
- n := copy(p, d.packetBuffers[0])
- d.packetBuffers = d.packetBuffers[1:]
- return n, nil
- }
- n, err := d.dev.Read(d.readBuffers, d.sizeBuffer, offset)
- if err != nil {
- return 0, err
- }
- if n == 0 {
- return 0, io.EOF
- }
- for i := range n {
- if d.sizeBuffer[i] <= 0 {
- continue
- }
- d.packetBuffers = append(d.packetBuffers, d.readBuffers[i][offset:offset+d.sizeBuffer[i]])
- }
- dataSize := copy(p, d.packetBuffers[0])
- d.packetBuffers = d.packetBuffers[1:]
- return dataSize, nil
- }
- func (d *tunDeviceWrapper) Write(p []byte) (int, error) {
- buf := pool.GetBuf(offset + d.bufferSize)
- defer pool.PutBuf(buf)
- n := copy(buf[offset:], p)
- _, err := d.dev.Write([][]byte{buf[:offset+n]}, offset)
- return n, err
- }
- func (d *tunDeviceWrapper) Close() error {
- return d.dev.Close()
- }
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