device: test packets between two fake devices

Signed-off-by: David Crawshaw <crawshaw@tailscale.io>

diff --git a/device/device_test.go b/device/device_test.go
index cdbd4583b0d2ada4d8c8d2351f669c205eebe378..14cc605edba324e6cbb3ff90e9172ffa3ee4906d 100644 (file)
--- a/device/device_test.go
+++ b/device/device_test.go
@@ -5,54 +5,212 @@
 
 package device
 
-/* Create two device instances and simulate full WireGuard interaction
- * without network dependencies
- */
-
 import (
+       "bufio"
        "bytes"
+       "encoding/binary"
+       "io"
+       "net"
+       "os"
+       "strings"
        "testing"
+       "time"
+
+       "golang.zx2c4.com/wireguard/tun"
 )
 
-func TestDevice(t *testing.T) {
+func TestTwoDevicePing(t *testing.T) {
+       // TODO(crawshaw): pick unused ports on localhost
+       cfg1 := `private_key=481eb0d8113a4a5da532d2c3e9c14b53c8454b34ab109676f6b58c2245e37b58
+listen_port=53511
+replace_peers=true
+public_key=f70dbb6b1b92a1dde1c783b297016af3f572fef13b0abb16a2623d89a58e9725
+protocol_version=1
+replace_allowed_ips=true
+allowed_ip=1.0.0.2/32
+endpoint=127.0.0.1:53512`
+       tun1 := NewChannelTUN()
+       dev1 := NewDevice(tun1.TUN(), NewLogger(LogLevelDebug, "dev1: "))
+       dev1.Up()
+       defer dev1.Close()
+       if err := dev1.IpcSetOperation(bufio.NewReader(strings.NewReader(cfg1))); err != nil {
+               t.Fatal(err)
+       }
 
-       // prepare tun devices for generating traffic
+       cfg2 := `private_key=98c7989b1661a0d64fd6af3502000f87716b7c4bbcf00d04fc6073aa7b539768
+listen_port=53512
+replace_peers=true
+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)
+       }
 
-       tun1 := newDummyTUN("tun1")
-       tun2 := newDummyTUN("tun2")
+       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")
+               }
+       })
+}
 
-       _ = tun1
-       _ = tun2
+func ping(dst, src net.IP) []byte {
+       localPort := uint16(1337)
+       seq := uint16(0)
 
-       // prepare endpoints
+       payload := make([]byte, 4)
+       binary.BigEndian.PutUint16(payload[0:], localPort)
+       binary.BigEndian.PutUint16(payload[2:], seq)
 
-       end1, err := CreateDummyEndpoint()
-       if err != nil {
-               t.Error("failed to create endpoint:", err.Error())
+       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)
+}
 
-       end2, err := CreateDummyEndpoint()
-       if err != nil {
-               t.Error("failed to create endpoint:", err.Error())
+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
+}
 
-       _ = end1
-       _ = end2
+type chTun struct {
+       c *ChannelTUN
+}
 
-       // create binds
+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
+       }
 }
 
-func randDevice(t *testing.T) *Device {
-       sk, err := newPrivateKey()
-       if err != nil {
-               t.Fatal(err)
+// 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
        }
-       tun := newDummyTUN("dummy")
-       logger := NewLogger(LogLevelError, "")
-       device := NewDevice(tun, logger)
-       device.SetPrivateKey(sk)
-       return device
+       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) {
@@ -66,3 +224,15 @@ func assertEqual(t *testing.T, a, b []byte) {
                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
+}