/
tunnelchannel.go
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/
tunnelchannel.go
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// Copyright 2020 ETH Zurich
//
// 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 ssh
import (
"context"
"crypto/tls"
"encoding/binary"
"fmt"
"io"
"net"
"sync"
"golang.org/x/crypto/ssh"
"inet.af/netaddr"
"github.com/netsec-ethz/scion-apps/pkg/pan"
"github.com/netsec-ethz/scion-apps/pkg/quicutil"
)
func handleTunnelForRemoteConnection(connection ssh.Channel, remoteConnection net.Conn) {
// Prepare teardown function
close := func() {
connection.Close()
remoteConnection.Close()
}
var once sync.Once
go func() {
_, _ = io.Copy(connection, remoteConnection)
once.Do(close)
}()
go func() {
_, _ = io.Copy(remoteConnection, connection)
once.Do(close)
}()
}
func handleTCPTunnel(perms *ssh.Permissions, newChannel ssh.NewChannel) error {
extraData := newChannel.ExtraData()
addressLen := binary.BigEndian.Uint32(extraData[0:4])
address := string(extraData[4 : addressLen+4])
port := binary.BigEndian.Uint32(extraData[addressLen+4 : addressLen+8])
connection, requests, err := newChannel.Accept()
if err != nil {
return fmt.Errorf("could not accept channel: %w", err)
}
go ssh.DiscardRequests(requests)
remoteConnection, err := net.Dial("tcp", fmt.Sprintf("%s:%v", address, port))
if err != nil {
return fmt.Errorf("could not open remote connection: %w", err)
}
handleTunnelForRemoteConnection(connection, remoteConnection)
return nil
}
func handleSCIONQUICTunnel(perms *ssh.Permissions, newChannel ssh.NewChannel) error {
extraData := newChannel.ExtraData()
addressLen := binary.BigEndian.Uint32(extraData[0:4])
address := string(extraData[4 : addressLen+4])
connection, requests, err := newChannel.Accept()
if err != nil {
return fmt.Errorf("could not accept channel: %w", err)
}
go ssh.DiscardRequests(requests)
ctx := context.Background()
remote, err := pan.ResolveUDPAddr(address)
if err != nil {
return fmt.Errorf("could not resolve remote address: %w", err)
}
tlsConf := &tls.Config{
NextProtos: []string{quicutil.SingleStreamProto},
InsecureSkipVerify: true,
}
sess, err := pan.DialQUIC(ctx, netaddr.IPPort{}, remote, nil, nil, "", tlsConf, nil)
if err != nil {
return fmt.Errorf("could not open remote connection: %w", err)
}
remoteConnection, err := quicutil.NewSingleStream(sess)
if err != nil {
return err
}
handleTunnelForRemoteConnection(connection, remoteConnection)
return nil
}