186 lines
4.9 KiB
Go
186 lines
4.9 KiB
Go
// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package main
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import (
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"context"
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"io/ioutil"
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"log"
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"os"
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"time"
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"flag"
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"github.com/google/subcommands"
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"gvisor.dev/gvisor/pkg/unet"
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"gvisor.dev/gvisor/runsc/testutil"
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)
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const fileContents = "foobarbaz"
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// fdSender will open a file and send the FD over a unix domain socket.
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type fdSender struct {
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socketPath string
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}
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// Name implements subcommands.Command.Name.
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func (*fdSender) Name() string {
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return "fd_sender"
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}
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// Synopsis implements subcommands.Command.Synopsys.
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func (*fdSender) Synopsis() string {
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return "creates a file and sends the FD over the socket"
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}
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// Usage implements subcommands.Command.Usage.
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func (*fdSender) Usage() string {
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return "fd_sender <flags>"
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}
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// SetFlags implements subcommands.Command.SetFlags.
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func (fds *fdSender) SetFlags(f *flag.FlagSet) {
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f.StringVar(&fds.socketPath, "socket", "", "path to socket")
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}
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// Execute implements subcommands.Command.Execute.
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func (fds *fdSender) Execute(ctx context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
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if fds.socketPath == "" {
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log.Fatalf("socket flag must be set")
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}
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dir, err := ioutil.TempDir("", "")
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if err != nil {
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log.Fatalf("TempDir failed: %v", err)
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}
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fileToSend, err := ioutil.TempFile(dir, "")
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if err != nil {
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log.Fatalf("TempFile failed: %v", err)
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}
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defer fileToSend.Close()
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if _, err := fileToSend.WriteString(fileContents); err != nil {
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log.Fatalf("Write(%q) failed: %v", fileContents, err)
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}
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// Receiver may not be started yet, so try connecting in a poll loop.
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var s *unet.Socket
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if err := testutil.Poll(func() error {
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var err error
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s, err = unet.Connect(fds.socketPath, true /* SEQPACKET, so we can send empty message with FD */)
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return err
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}, 10*time.Second); err != nil {
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log.Fatalf("Error connecting to socket %q: %v", fds.socketPath, err)
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}
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defer s.Close()
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w := s.Writer(true)
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w.ControlMessage.PackFDs(int(fileToSend.Fd()))
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if _, err := w.WriteVec([][]byte{[]byte{'a'}}); err != nil {
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log.Fatalf("Error sending FD %q over socket %q: %v", fileToSend.Fd(), fds.socketPath, err)
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}
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log.Print("FD SENDER exiting successfully")
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return subcommands.ExitSuccess
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}
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// fdReceiver receives an FD from a unix domain socket and does things to it.
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type fdReceiver struct {
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socketPath string
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}
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// Name implements subcommands.Command.Name.
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func (*fdReceiver) Name() string {
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return "fd_receiver"
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}
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// Synopsis implements subcommands.Command.Synopsys.
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func (*fdReceiver) Synopsis() string {
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return "reads an FD from a unix socket, and then does things to it"
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}
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// Usage implements subcommands.Command.Usage.
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func (*fdReceiver) Usage() string {
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return "fd_receiver <flags>"
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}
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// SetFlags implements subcommands.Command.SetFlags.
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func (fdr *fdReceiver) SetFlags(f *flag.FlagSet) {
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f.StringVar(&fdr.socketPath, "socket", "", "path to socket")
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}
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// Execute implements subcommands.Command.Execute.
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func (fdr *fdReceiver) Execute(ctx context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
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if fdr.socketPath == "" {
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log.Fatalf("Flags cannot be empty, given: socket: %q", fdr.socketPath)
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}
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ss, err := unet.BindAndListen(fdr.socketPath, true /* packet */)
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if err != nil {
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log.Fatalf("BindAndListen(%q) failed: %v", fdr.socketPath, err)
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}
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defer ss.Close()
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var s *unet.Socket
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c := make(chan error, 1)
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go func() {
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var err error
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s, err = ss.Accept()
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c <- err
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}()
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select {
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case err := <-c:
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if err != nil {
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log.Fatalf("Accept() failed: %v", err)
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}
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case <-time.After(10 * time.Second):
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log.Fatalf("Timeout waiting for accept")
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}
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r := s.Reader(true)
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r.EnableFDs(1)
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b := [][]byte{{'a'}}
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if n, err := r.ReadVec(b); n != 1 || err != nil {
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log.Fatalf("ReadVec got n=%d err %v (wanted 0, nil)", n, err)
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}
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fds, err := r.ExtractFDs()
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if err != nil {
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log.Fatalf("ExtractFD() got err %v", err)
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}
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if len(fds) != 1 {
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log.Fatalf("ExtractFD() got %d FDs, wanted 1", len(fds))
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}
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fd := fds[0]
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file := os.NewFile(uintptr(fd), "received file")
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defer file.Close()
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if _, err := file.Seek(0, os.SEEK_SET); err != nil {
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log.Fatalf("Seek(0, 0) failed: %v", err)
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}
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got, err := ioutil.ReadAll(file)
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if err != nil {
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log.Fatalf("ReadAll failed: %v", err)
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}
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if string(got) != fileContents {
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log.Fatalf("ReadAll got %q want %q", string(got), fileContents)
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}
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log.Print("FD RECEIVER exiting successfully")
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return subcommands.ExitSuccess
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}
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