device: test packets between two fake devices

Signed-off-by: David Crawshaw <crawshaw@tailscale.io>
This commit is contained in:
David Crawshaw 2019-10-12 12:44:05 -04:00 committed by Jason A. Donenfeld
parent f2ea85e9f9
commit 540d01e54a

View file

@ -5,54 +5,212 @@
package device package device
/* Create two device instances and simulate full WireGuard interaction
* without network dependencies
*/
import ( import (
"bufio"
"bytes" "bytes"
"encoding/binary"
"io"
"net"
"os"
"strings"
"testing" "testing"
"time"
"golang.zx2c4.com/wireguard/tun"
) )
func TestDevice(t *testing.T) { func TestTwoDevicePing(t *testing.T) {
// TODO(crawshaw): pick unused ports on localhost
// prepare tun devices for generating traffic cfg1 := `private_key=481eb0d8113a4a5da532d2c3e9c14b53c8454b34ab109676f6b58c2245e37b58
listen_port=53511
tun1 := newDummyTUN("tun1") replace_peers=true
tun2 := newDummyTUN("tun2") public_key=f70dbb6b1b92a1dde1c783b297016af3f572fef13b0abb16a2623d89a58e9725
protocol_version=1
_ = tun1 replace_allowed_ips=true
_ = tun2 allowed_ip=1.0.0.2/32
endpoint=127.0.0.1:53512`
// prepare endpoints tun1 := NewChannelTUN()
dev1 := NewDevice(tun1.TUN(), NewLogger(LogLevelDebug, "dev1: "))
end1, err := CreateDummyEndpoint() dev1.Up()
if err != nil { defer dev1.Close()
t.Error("failed to create endpoint:", err.Error()) if err := dev1.IpcSetOperation(bufio.NewReader(strings.NewReader(cfg1))); err != nil {
}
end2, err := CreateDummyEndpoint()
if err != nil {
t.Error("failed to create endpoint:", err.Error())
}
_ = end1
_ = end2
// create binds
}
func randDevice(t *testing.T) *Device {
sk, err := newPrivateKey()
if err != nil {
t.Fatal(err) t.Fatal(err)
} }
tun := newDummyTUN("dummy")
logger := NewLogger(LogLevelError, "") cfg2 := `private_key=98c7989b1661a0d64fd6af3502000f87716b7c4bbcf00d04fc6073aa7b539768
device := NewDevice(tun, logger) listen_port=53512
device.SetPrivateKey(sk) replace_peers=true
return device public_key=49e80929259cebdda4f322d6d2b1a6fad819d603acd26fd5d845e7a123036427
protocol_version=1
replace_allowed_ips=true
allowed_ip=1.0.0.1/32
endpoint=127.0.0.1:53511`
tun2 := NewChannelTUN()
dev2 := NewDevice(tun2.TUN(), NewLogger(LogLevelDebug, "dev2: "))
dev2.Up()
defer dev2.Close()
if err := dev2.IpcSetOperation(bufio.NewReader(strings.NewReader(cfg2))); err != nil {
t.Fatal(err)
}
t.Run("ping 1.0.0.1", func(t *testing.T) {
msg2to1 := ping(net.ParseIP("1.0.0.1"), net.ParseIP("1.0.0.2"))
tun2.Outbound <- msg2to1
select {
case msgRecv := <-tun1.Inbound:
if !bytes.Equal(msg2to1, msgRecv) {
t.Error("ping did not transit correctly")
}
case <-time.After(300 * time.Millisecond):
t.Error("ping did not transit")
}
})
t.Run("ping 1.0.0.2", func(t *testing.T) {
msg1to2 := ping(net.ParseIP("1.0.0.2"), net.ParseIP("1.0.0.1"))
tun1.Outbound <- msg1to2
select {
case msgRecv := <-tun2.Inbound:
if !bytes.Equal(msg1to2, msgRecv) {
t.Error("return ping did not transit correctly")
}
case <-time.After(300 * time.Millisecond):
t.Error("return ping did not transit")
}
})
}
func ping(dst, src net.IP) []byte {
localPort := uint16(1337)
seq := uint16(0)
payload := make([]byte, 4)
binary.BigEndian.PutUint16(payload[0:], localPort)
binary.BigEndian.PutUint16(payload[2:], seq)
return genICMPv4(payload, dst, src)
}
// checksum is the "internet checksum" from https://tools.ietf.org/html/rfc1071.
func checksum(buf []byte, initial uint16) uint16 {
v := uint32(initial)
for i := 0; i < len(buf)-1; i += 2 {
v += uint32(binary.BigEndian.Uint16(buf[i:]))
}
if len(buf)%2 == 1 {
v += uint32(buf[len(buf)-1]) << 8
}
for v > 0xffff {
v = (v >> 16) + (v & 0xffff)
}
return ^uint16(v)
}
func genICMPv4(payload []byte, dst, src net.IP) []byte {
const (
icmpv4ProtocolNumber = 1
icmpv4Echo = 8
icmpv4ChecksumOffset = 2
icmpv4Size = 8
ipv4Size = 20
ipv4TotalLenOffset = 2
ipv4ChecksumOffset = 10
ttl = 65
)
hdr := make([]byte, ipv4Size+icmpv4Size)
ip := hdr[0:ipv4Size]
icmpv4 := hdr[ipv4Size : ipv4Size+icmpv4Size]
// https://tools.ietf.org/html/rfc792
icmpv4[0] = icmpv4Echo // type
icmpv4[1] = 0 // code
chksum := ^checksum(icmpv4, checksum(payload, 0))
binary.BigEndian.PutUint16(icmpv4[icmpv4ChecksumOffset:], chksum)
// https://tools.ietf.org/html/rfc760 section 3.1
length := uint16(len(hdr) + len(payload))
ip[0] = (4 << 4) | (ipv4Size / 4)
binary.BigEndian.PutUint16(ip[ipv4TotalLenOffset:], length)
ip[8] = ttl
ip[9] = icmpv4ProtocolNumber
copy(ip[12:], src.To4())
copy(ip[16:], dst.To4())
chksum = ^checksum(ip[:], 0)
binary.BigEndian.PutUint16(ip[ipv4ChecksumOffset:], chksum)
var v []byte
v = append(v, hdr...)
v = append(v, payload...)
return []byte(v)
}
// TODO(crawshaw): find a reusable home for this. package devicetest?
type ChannelTUN struct {
Inbound chan []byte // incoming packets, closed on TUN close
Outbound chan []byte // outbound packets, blocks forever on TUN close
closed chan struct{}
events chan tun.Event
tun chTun
}
func NewChannelTUN() *ChannelTUN {
c := &ChannelTUN{
Inbound: make(chan []byte),
Outbound: make(chan []byte),
closed: make(chan struct{}),
events: make(chan tun.Event, 1),
}
c.tun.c = c
c.events <- tun.EventUp
return c
}
func (c *ChannelTUN) TUN() tun.Device {
return &c.tun
}
type chTun struct {
c *ChannelTUN
}
func (t *chTun) File() *os.File { return nil }
func (t *chTun) Read(data []byte, offset int) (int, error) {
select {
case <-t.c.closed:
return 0, io.EOF // TODO(crawshaw): what is the correct error value?
case msg := <-t.c.Outbound:
return copy(data[offset:], msg), nil
}
}
// Write is called by the wireguard device to deliver a packet for routing.
func (t *chTun) Write(data []byte, offset int) (int, error) {
if offset == -1 {
close(t.c.closed)
close(t.c.events)
return 0, io.EOF
}
msg := make([]byte, len(data)-offset)
copy(msg, data[offset:])
select {
case <-t.c.closed:
return 0, io.EOF // TODO(crawshaw): what is the correct error value?
case t.c.Inbound <- msg:
return len(data) - offset, nil
}
}
func (t *chTun) Flush() error { return nil }
func (t *chTun) MTU() (int, error) { return DefaultMTU, nil }
func (t *chTun) Name() (string, error) { return "loopbackTun1", nil }
func (t *chTun) Events() chan tun.Event { return t.c.events }
func (t *chTun) Close() error {
t.Write(nil, -1)
return nil
} }
func assertNil(t *testing.T, err error) { func assertNil(t *testing.T, err error) {
@ -66,3 +224,15 @@ func assertEqual(t *testing.T, a, b []byte) {
t.Fatal(a, "!=", b) t.Fatal(a, "!=", b)
} }
} }
func randDevice(t *testing.T) *Device {
sk, err := newPrivateKey()
if err != nil {
t.Fatal(err)
}
tun := newDummyTUN("dummy")
logger := NewLogger(LogLevelError, "")
device := NewDevice(tun, logger)
device.SetPrivateKey(sk)
return device
}