// TestPassFD tests passing a file descriptor over a Unix socket.
//
// This test involved both a parent and child process. The parent
// process is invoked as a normal test, with "go test", which then
// runs the child process by running the current test binary with args
// "-test.run=^TestPassFD$" and an environment variable used to signal
// that the test should become the child process instead.
func TestPassFD(t *testing.T) {
switch runtime.GOOS {
case "dragonfly":
// TODO(jsing): Figure out why sendmsg is returning EINVAL.
t.Skip("skipping test on dragonfly")
case "solaris":
// TODO(aram): Figure out why ReadMsgUnix is returning empty message.
t.Skip("skipping test on solaris, see issue 7402")
}
if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
passFDChild()
return
}
tempDir, err := ioutil.TempDir("", "TestPassFD")
if err != nil {
t.Fatal(err)
}
defer os.RemoveAll(tempDir)
fds, err := unix.Socketpair(unix.AF_LOCAL, unix.SOCK_STREAM, 0)
if err != nil {
t.Fatalf("Socketpair: %v", err)
}
defer unix.Close(fds[0])
defer unix.Close(fds[1])
writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
defer writeFile.Close()
defer readFile.Close()
cmd := exec.Command(os.Args[0], "-test.run=^TestPassFD$", "--", tempDir)
cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
if lp := os.Getenv("LD_LIBRARY_PATH"); lp != "" {
cmd.Env = append(cmd.Env, "LD_LIBRARY_PATH="+lp)
}
cmd.ExtraFiles = []*os.File{writeFile}
out, err := cmd.CombinedOutput()
if len(out) > 0 || err != nil {
t.Fatalf("child process: %q, %v", out, err)
}
c, err := net.FileConn(readFile)
if err != nil {
t.Fatalf("FileConn: %v", err)
}
defer c.Close()
uc, ok := c.(*net.UnixConn)
if !ok {
t.Fatalf("unexpected FileConn type; expected UnixConn, got %T", c)
}
buf := make([]byte, 32) // expect 1 byte
oob := make([]byte, 32) // expect 24 bytes
closeUnix := time.AfterFunc(5*time.Second, func() {
t.Logf("timeout reading from unix socket")
uc.Close()
})
_, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
closeUnix.Stop()
scms, err := unix.ParseSocketControlMessage(oob[:oobn])
if err != nil {
t.Fatalf("ParseSocketControlMessage: %v", err)
}
if len(scms) != 1 {
t.Fatalf("expected 1 SocketControlMessage; got scms = %#v", scms)
}
scm := scms[0]
gotFds, err := unix.ParseUnixRights(&scm)
if err != nil {
t.Fatalf("unix.ParseUnixRights: %v", err)
}
if len(gotFds) != 1 {
t.Fatalf("wanted 1 fd; got %#v", gotFds)
}
f := os.NewFile(uintptr(gotFds[0]), "fd-from-child")
defer f.Close()
got, err := ioutil.ReadAll(f)
want := "Hello from child process!\n"
if string(got) != want {
t.Errorf("child process ReadAll: %q, %v; want %q", got, err, want)
}
}
// TestSCMCredentials tests the sending and receiving of credentials
// (PID, UID, GID) in an ancillary message between two UNIX
// sockets. The SO_PASSCRED socket option is enabled on the sending
// socket for this to work.
func TestSCMCredentials(t *testing.T) {
fds, err := unix.Socketpair(unix.AF_LOCAL, unix.SOCK_STREAM, 0)
if err != nil {
t.Fatalf("Socketpair: %v", err)
}
defer unix.Close(fds[0])
defer unix.Close(fds[1])
err = unix.SetsockoptInt(fds[0], unix.SOL_SOCKET, unix.SO_PASSCRED, 1)
if err != nil {
t.Fatalf("SetsockoptInt: %v", err)
}
srvFile := os.NewFile(uintptr(fds[0]), "server")
defer srvFile.Close()
srv, err := net.FileConn(srvFile)
if err != nil {
t.Errorf("FileConn: %v", err)
return
}
defer srv.Close()
cliFile := os.NewFile(uintptr(fds[1]), "client")
defer cliFile.Close()
cli, err := net.FileConn(cliFile)
if err != nil {
t.Errorf("FileConn: %v", err)
return
}
defer cli.Close()
var ucred unix.Ucred
if os.Getuid() != 0 {
ucred.Pid = int32(os.Getpid())
ucred.Uid = 0
ucred.Gid = 0
oob := unix.UnixCredentials(&ucred)
_, _, err := cli.(*net.UnixConn).WriteMsgUnix(nil, oob, nil)
if op, ok := err.(*net.OpError); ok {
err = op.Err
}
if sys, ok := err.(*os.SyscallError); ok {
err = sys.Err
}
if err != syscall.EPERM {
t.Fatalf("WriteMsgUnix failed with %v, want EPERM", err)
}
}
ucred.Pid = int32(os.Getpid())
ucred.Uid = uint32(os.Getuid())
ucred.Gid = uint32(os.Getgid())
oob := unix.UnixCredentials(&ucred)
// this is going to send a dummy byte
n, oobn, err := cli.(*net.UnixConn).WriteMsgUnix(nil, oob, nil)
if err != nil {
t.Fatalf("WriteMsgUnix: %v", err)
}
if n != 0 {
t.Fatalf("WriteMsgUnix n = %d, want 0", n)
}
if oobn != len(oob) {
t.Fatalf("WriteMsgUnix oobn = %d, want %d", oobn, len(oob))
}
oob2 := make([]byte, 10*len(oob))
n, oobn2, flags, _, err := srv.(*net.UnixConn).ReadMsgUnix(nil, oob2)
if err != nil {
t.Fatalf("ReadMsgUnix: %v", err)
}
if flags != 0 {
t.Fatalf("ReadMsgUnix flags = 0x%x, want 0", flags)
}
if n != 1 {
t.Fatalf("ReadMsgUnix n = %d, want 1 (dummy byte)", n)
}
if oobn2 != oobn {
// without SO_PASSCRED set on the socket, ReadMsgUnix will
// return zero oob bytes
t.Fatalf("ReadMsgUnix oobn = %d, want %d", oobn2, oobn)
}
oob2 = oob2[:oobn2]
if !bytes.Equal(oob, oob2) {
t.Fatal("ReadMsgUnix oob bytes don't match")
}
scm, err := unix.ParseSocketControlMessage(oob2)
if err != nil {
t.Fatalf("ParseSocketControlMessage: %v", err)
}
newUcred, err := unix.ParseUnixCredentials(&scm[0])
if err != nil {
t.Fatalf("ParseUnixCredentials: %v", err)
}
if *newUcred != ucred {
t.Fatalf("ParseUnixCredentials = %+v, want %+v", newUcred, ucred)
}
}