1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
// Copyright 2016 The Netstack Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This sample creates a stack with TCP and IPv4 protocols on top of a TUN
// device, and connects to a peer. Similar to "nc <address> <port>". While the
// sample is running, attempts to connect to its IPv4 address will result in
// a RST segment.
//
// As an example of how to run it, a TUN device can be created and enabled on
// a linux host as follows (this only needs to be done once per boot):
//
// [sudo] ip tuntap add user <username> mode tun <device-name>
// [sudo] ip link set <device-name> up
// [sudo] ip addr add <ipv4-address>/<mask-length> dev <device-name>
//
// A concrete example:
//
// $ sudo ip tuntap add user wedsonaf mode tun tun0
// $ sudo ip link set tun0 up
// $ sudo ip addr add 192.168.1.1/24 dev tun0
//
// Then one can run tun_tcp_connect as such:
//
// $ ./tun/tun_tcp_connect tun0 192.168.1.2 0 192.168.1.1 1234
//
// This will attempt to connect to the linux host's stack. One can run nc in
// listen mode to accept a connect from tun_tcp_connect and exchange data.
package main
import (
"bufio"
"fmt"
"log"
"math/rand"
"net"
"os"
"strconv"
"time"
"gvisor.googlesource.com/gvisor/pkg/tcpip"
"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
"gvisor.googlesource.com/gvisor/pkg/tcpip/link/fdbased"
"gvisor.googlesource.com/gvisor/pkg/tcpip/link/rawfile"
"gvisor.googlesource.com/gvisor/pkg/tcpip/link/sniffer"
"gvisor.googlesource.com/gvisor/pkg/tcpip/link/tun"
"gvisor.googlesource.com/gvisor/pkg/tcpip/network/ipv4"
"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
"gvisor.googlesource.com/gvisor/pkg/tcpip/transport/tcp"
"gvisor.googlesource.com/gvisor/pkg/waiter"
)
// writer reads from standard input and writes to the endpoint until standard
// input is closed. It signals that it's done by closing the provided channel.
func writer(ch chan struct{}, ep tcpip.Endpoint) {
defer func() {
ep.Shutdown(tcpip.ShutdownWrite)
close(ch)
}()
r := bufio.NewReader(os.Stdin)
for {
v := buffer.NewView(1024)
n, err := r.Read(v)
if err != nil {
return
}
v.CapLength(n)
for len(v) > 0 {
n, err := ep.Write(tcpip.SlicePayload(v), tcpip.WriteOptions{})
if err != nil {
fmt.Println("Write failed:", err)
return
}
v.TrimFront(int(n))
}
}
}
func main() {
if len(os.Args) != 6 {
log.Fatal("Usage: ", os.Args[0], " <tun-device> <local-ipv4-address> <local-port> <remote-ipv4-address> <remote-port>")
}
tunName := os.Args[1]
addrName := os.Args[2]
portName := os.Args[3]
remoteAddrName := os.Args[4]
remotePortName := os.Args[5]
rand.Seed(time.Now().UnixNano())
addr := tcpip.Address(net.ParseIP(addrName).To4())
remote := tcpip.FullAddress{
NIC: 1,
Addr: tcpip.Address(net.ParseIP(remoteAddrName).To4()),
}
var localPort uint16
if v, err := strconv.Atoi(portName); err != nil {
log.Fatalf("Unable to convert port %v: %v", portName, err)
} else {
localPort = uint16(v)
}
if v, err := strconv.Atoi(remotePortName); err != nil {
log.Fatalf("Unable to convert port %v: %v", remotePortName, err)
} else {
remote.Port = uint16(v)
}
// Create the stack with ipv4 and tcp protocols, then add a tun-based
// NIC and ipv4 address.
s := stack.New([]string{ipv4.ProtocolName}, []string{tcp.ProtocolName})
mtu, err := rawfile.GetMTU(tunName)
if err != nil {
log.Fatal(err)
}
fd, err := tun.Open(tunName)
if err != nil {
log.Fatal(err)
}
linkID := fdbased.New(&fdbased.Options{FD: fd, MTU: mtu})
if err := s.CreateNIC(1, sniffer.New(linkID)); err != nil {
log.Fatal(err)
}
if err := s.AddAddress(1, ipv4.ProtocolNumber, addr); err != nil {
log.Fatal(err)
}
// Add default route.
s.SetRouteTable([]tcpip.Route{
{
Destination: "\x00\x00\x00\x00",
Mask: "\x00\x00\x00\x00",
Gateway: "",
NIC: 1,
},
})
// Create TCP endpoint.
var wq waiter.Queue
ep, e := s.NewEndpoint(tcp.ProtocolNumber, ipv4.ProtocolNumber, &wq)
if err != nil {
log.Fatal(e)
}
// Bind if a port is specified.
if localPort != 0 {
if err := ep.Bind(tcpip.FullAddress{0, "", localPort}, nil); err != nil {
log.Fatal("Bind failed: ", err)
}
}
// Issue connect request and wait for it to complete.
waitEntry, notifyCh := waiter.NewChannelEntry(nil)
wq.EventRegister(&waitEntry, waiter.EventOut)
terr := ep.Connect(remote)
if terr == tcpip.ErrConnectStarted {
fmt.Println("Connect is pending...")
<-notifyCh
terr = ep.GetSockOpt(tcpip.ErrorOption{})
}
wq.EventUnregister(&waitEntry)
if terr != nil {
log.Fatal("Unable to connect: ", terr)
}
fmt.Println("Connected")
// Start the writer in its own goroutine.
writerCompletedCh := make(chan struct{})
go writer(writerCompletedCh, ep) // S/R-FIXME
// Read data and write to standard output until the peer closes the
// connection from its side.
wq.EventRegister(&waitEntry, waiter.EventIn)
for {
v, err := ep.Read(nil)
if err != nil {
if err == tcpip.ErrClosedForReceive {
break
}
if err == tcpip.ErrWouldBlock {
<-notifyCh
continue
}
log.Fatal("Read() failed:", err)
}
os.Stdout.Write(v)
}
wq.EventUnregister(&waitEntry)
// The reader has completed. Now wait for the writer as well.
<-writerCompletedCh
ep.Close()
}
|
