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// Copyright 2021 The gVisor 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 tunnel
import (
"context"
"errors"
"log"
"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/network/ipv4"
"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
"gvisor.dev/gvisor/pkg/tcpip/stack"
"gvisor.dev/gvisor/pkg/tcpip/transport/gre"
"gvisor.dev/gvisor/pkg/tcpip/transport/raw"
"gvisor.dev/gvisor/pkg/waiter"
)
var SIZE = 16
type Endpoint struct {
channel.Endpoint
LocalAddr tcpip.Address
RemoteAddr tcpip.Address
}
type writer Endpoint
func New(mtu uint32) *Endpoint {
var linkAddress tcpip.LinkAddress
ch := channel.New(SIZE, mtu, linkAddress)
return &Endpoint{
Endpoint: *ch,
}
}
func (e *Endpoint) GetChannel() *channel.Endpoint {
return &e.Endpoint
}
func (e *Endpoint) GetLocalAddress() tcpip.Address {
return e.LocalAddr
}
func (e *Endpoint) GetRemoteAddress() tcpip.Address {
return e.RemoteAddr
}
// Attach saves the stack network-layer dispatcher for use later when packets
// are injected.
func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) {
log.Println("GRE: Attach")
e.Endpoint.Attach(dispatcher)
}
type GrePacketInfo struct {
pi *channel.PacketInfo
}
func (g GrePacketInfo) Len() int {
return g.pi.Pkt.Size()
}
func (g GrePacketInfo) Read(p []byte) (n int, err error){
pkt := g.pi.Pkt
size := pkt.Size()
if size > len(p) {
return 0, errors.New("Buffer too small")
}
vv := buffer.NewVectorisedView(size, pkt.Views())
pos := 0
for {
copied, err := vv.Read(p[pos:])
log.Printf("VectorisedView Read: %d %d %d %v", size, pos, copied, err)
if err != nil {
return 0, errors.New("&tcpip.ErrBadBuffer{}")
}
pos = pos + copied
if pos == size {
break
}
}
return pos, nil
}
func (g GrePacketInfo) Payload(size int) ([]byte, tcpip.Error){
log.Println("Payload")
return nil, &tcpip.ErrNotSupported{}
}
type GreHandlerInfo struct {
ChEp *channel.Endpoint
Raw tcpip.Endpoint
Raddr tcpip.FullAddress
Stack *stack.Stack
NIC tcpip.NICID
}
func (info *GreHandlerInfo) greHandler(req *gre.ForwarderRequest) {
pkt := req.Pkt
log.Println("greHandler: ", req.Pkt.Size(), req.Pkt.Views())
greHdr := header.GRE(pkt.TransportHeader().View())
proto := greHdr.ProtocolType()
pktData := pkt.Data()
views := pktData.Views()
size := pktData.Size()
data := buffer.NewVectorisedView(size, views)
newPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
Data: data,
})
log.Printf("greHandler proto: %d cloned: %v", proto, newPkt.Views())
info.ChEp.InjectInbound(proto, newPkt)
}
func ipAny(protocol tcpip.NetworkProtocolNumber) (tcpip.Address, tcpip.Error) {
switch protocol {
case header.IPv4ProtocolNumber:
return header.IPv4Any, nil
case header.IPv6ProtocolNumber:
return header.IPv6Any, nil
default:
log.Printf("Unsupported protocol %v", protocol)
return tcpip.Address([]byte{}), &tcpip.ErrNotSupported{}
}
}
func (info *GreHandlerInfo) greRead(ep *channel.Endpoint) {
for {
pi, err := ep.ReadContext(context.Background());
linkHdr := pi.Pkt.LinkHeader()
greHdr := header.GRE(linkHdr.Push(header.GREHeaderSize))
greHdr.SetProtocolType(pi.Proto)
log.Printf("greRead %d %v %v %v", pi.Proto, pi, err, greHdr)
opts := tcpip.WriteOptions{
//To: &info.Raddr
}
if info.Raddr.Addr == header.IPv4Any {
protocol := pi.Pkt.NetworkProtocolNumber
nw := pi.Pkt.Network()
addr := nw.DestinationAddress()
laddr, err := ipAny(protocol); if err != nil {
continue
}
err = info.Stack.GetLinkAddress(info.NIC, addr, laddr, protocol, func (res stack.LinkResolutionResult) {
if res.Err != nil {
return
}
opts.To = &tcpip.FullAddress{
NIC: 0,
Addr: tcpip.Address(res.LinkAddress),
}
})
if err != nil {
continue
}
}
info.Raw.Write(GrePacketInfo{&pi}, opts)
}
}
func networkProtocolNumber(addr *tcpip.Address) tcpip.NetworkProtocolNumber {
if addr.To4() != "" {
return ipv4.ProtocolNumber
} else {
return ipv6.ProtocolNumber
}
}
// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType.
func (*Endpoint) ARPHardwareType() header.ARPHardwareType {
return header.ARPHardwareIPGRE
}
func (e *Endpoint) Start(s *stack.Stack, nic tcpip.NICID, laddr, raddr *tcpip.Address) tcpip.Error {
proto := networkProtocolNumber(laddr)
if proto != networkProtocolNumber(raddr) {
return &tcpip.ErrBadAddress{}
}
// Create TCP endpoint.
var rawWq waiter.Queue
rawEp, tcperr := raw.NewEndpoint(s, proto, header.GREProtocolNumber, &rawWq)
if tcperr != nil {
return tcperr
}
log.Println("EP: %s", rawEp)
e.LocalAddr = *laddr
e.RemoteAddr = *raddr
fraddr := tcpip.FullAddress{NIC: 0, Addr: *raddr}
flAddr := tcpip.FullAddress{NIC: 0, Addr: *laddr}
tcperr = rawEp.Bind(flAddr)
if tcperr != nil {
return tcperr
}
log.Printf("Remote: %v %v", raddr, fraddr)
// Create GRE
// greEP := grelink.New(mtu - 24)
chEP := e.GetChannel()
// TODO detect IPv4/IPv6
e.NMaxHeaderLength = header.IPv6FixedHeaderSize + header.GREHeaderSize
greInfo := GreHandlerInfo{
// Ep: loEP,
ChEp: chEP,
Raw: rawEp,
Raddr: fraddr,
Stack: s,
NIC: nic,
}
greFwd := gre.NewForwarder(s, greInfo.greHandler)
s.SetTransportProtocolHandler(header.GREProtocolNumber, greFwd.HandlePacket)
go greInfo.greRead(chEP)
any, _ := ipAny(proto)
if fraddr.Addr != any {
tcperr = rawEp.Connect(fraddr)
if tcperr != nil {
return tcperr
}
}
return nil
}
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