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