reuse_test.go

   1 package torrent
   2
   3 import (
   4         "context"
   5         "errors"
   6         "net"
   7         "sync/atomic"
   8         "syscall"
   9         "testing"
  10
  11         "github.com/anacrolix/log"
  12         qt "github.com/frankban/quicktest"
  13 )
  14
  15 // Show that multiple connections from the same local TCP port to the same remote port will fail.
  16 func TestTcpPortReuseIsABadIdea(t *testing.T) {
  17         remote, err := net.Listen("tcp", "localhost:0")
  18         c := qt.New(t)
  19         c.Assert(err, qt.IsNil)
  20         defer remote.Close()
  21         dialer := net.Dialer{}
  22         dialer.Control = func(network, address string, c syscall.RawConn) (err error) {
  23                 return c.Control(func(fd uintptr) {
  24                         err = setReusePortSockOpts(fd)
  25                 })
  26         }
  27         first, err := dialer.Dial("tcp", remote.Addr().String())
  28         c.Assert(err, qt.IsNil)
  29         defer first.Close()
  30         dialer.LocalAddr = first.LocalAddr()
  31         _, err = dialer.Dial("tcp", remote.Addr().String())
  32         c.Assert(errors.Is(err, syscall.EADDRINUSE), qt.IsTrue)
  33 }
  34
  35 // Show that multiple connections from the same local utp socket to the same remote port will
  36 // succeed. This is necessary for ut_holepunch to work.
  37 func TestUtpLocalPortIsReusable(t *testing.T) {
  38         const network = "udp"
  39         c := qt.New(t)
  40         remote, err := NewUtpSocket(network, "localhost:0", nil, log.Default)
  41         c.Assert(err, qt.IsNil)
  42         defer remote.Close()
  43         var remoteAccepts int32
  44         doneAccepting := make(chan struct{})
  45         go func() {
  46                 defer close(doneAccepting)
  47                 for {
  48                         c, err := remote.Accept()
  49                         if err != nil {
  50                                 if atomic.LoadInt32(&remoteAccepts) != 2 {
  51                                         t.Logf("error accepting on remote: %v", err)
  52                                 }
  53                                 break
  54                         }
  55                         // This is not a leak, bugger off.
  56                         defer c.Close()
  57                         atomic.AddInt32(&remoteAccepts, 1)
  58                 }
  59         }()
  60         local, err := NewUtpSocket(network, "localhost:0", nil, log.Default)
  61         c.Assert(err, qt.IsNil)
  62         defer local.Close()
  63         first, err := local.DialContext(context.Background(), network, remote.Addr().String())
  64         c.Assert(err, qt.IsNil)
  65         defer first.Close()
  66         second, err := local.DialContext(context.Background(), network, remote.Addr().String())
  67         c.Assert(err, qt.IsNil)
  68         defer second.Close()
  69         remote.Close()
  70         <-doneAccepting
  71         c.Assert(atomic.LoadInt32(&remoteAccepts), qt.Equals, int32(2))
  72 }