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package virtwriter
import (
"bufio"
"encoding/binary"
"encoding/json"
"io"
"time"
"github.com/pkg/errors"
"k8s.io/client-go/tools/remotecommand"
)
// SocketDest is the "key" to where IO should go on the varlink
// multiplexed socket
type SocketDest int
const (
// ToStdout indicates traffic should go stdout
ToStdout SocketDest = iota
// ToStdin indicates traffic came from stdin
ToStdin SocketDest = iota
// ToStderr indicates traffuc should go to stderr
ToStderr SocketDest = iota
// TerminalResize indicates a terminal resize event has occurred
// and data should be passed to resizer
TerminalResize SocketDest = iota
// Quit and detach
Quit SocketDest = iota
// HangUpFromClient hangs up from the client
HangUpFromClient SocketDest = iota
)
// ErrClientHangup signifies that the client wants to drop its connection from
// the server.
var ErrClientHangup = errors.New("client hangup")
// IntToSocketDest returns a socketdest based on integer input
func IntToSocketDest(i int) SocketDest {
switch i {
case ToStdout.Int():
return ToStdout
case ToStderr.Int():
return ToStderr
case ToStdin.Int():
return ToStdin
case TerminalResize.Int():
return TerminalResize
case Quit.Int():
return Quit
case HangUpFromClient.Int():
return HangUpFromClient
default:
return ToStderr
}
}
// Int returns the integer representation of the socket dest
func (sd SocketDest) Int() int {
return int(sd)
}
// VirtWriteCloser are writers for attach which include the dest
// of the data
type VirtWriteCloser struct {
writer *bufio.Writer
dest SocketDest
}
// NewVirtWriteCloser is a constructor
func NewVirtWriteCloser(w *bufio.Writer, dest SocketDest) VirtWriteCloser {
return VirtWriteCloser{w, dest}
}
// Close is a required method for a writecloser
func (v VirtWriteCloser) Close() error {
return v.writer.Flush()
}
// Write prepends a header to the input message. The header is
// 8bytes. Position one contains the destination. Positions
// 5,6,7,8 are a big-endian encoded uint32 for len of the message.
func (v VirtWriteCloser) Write(input []byte) (int, error) {
header := []byte{byte(v.dest), 0, 0, 0}
// Go makes us define the byte for big endian
mlen := make([]byte, 4)
binary.BigEndian.PutUint32(mlen, uint32(len(input)))
// append the message len to the header
msg := append(header, mlen...)
// append the message to the header
msg = append(msg, input...)
_, err := v.writer.Write(msg)
if err != nil {
return 0, err
}
err = v.writer.Flush()
return len(input), err
}
// Reader decodes the content that comes over the wire and directs it to the proper destination.
func Reader(r *bufio.Reader, output, errput, input io.Writer, resize chan remotecommand.TerminalSize, execEcChan chan int) error {
var messageSize int64
headerBytes := make([]byte, 8)
if r == nil {
return errors.Errorf("Reader must not be nil")
}
for {
n, err := io.ReadFull(r, headerBytes)
if err != nil {
return errors.Wrapf(err, "Virtual Read failed, %d", n)
}
if n < 8 {
return errors.New("short read and no full header read")
}
messageSize = int64(binary.BigEndian.Uint32(headerBytes[4:8]))
switch IntToSocketDest(int(headerBytes[0])) {
case ToStdout:
if output != nil {
_, err := io.CopyN(output, r, messageSize)
if err != nil {
return err
}
}
case ToStderr:
if errput != nil {
_, err := io.CopyN(errput, r, messageSize)
if err != nil {
return err
}
}
case ToStdin:
if input != nil {
_, err := io.CopyN(input, r, messageSize)
if err != nil {
return err
}
}
case TerminalResize:
if resize != nil {
out := make([]byte, messageSize)
if messageSize > 0 {
_, err = io.ReadFull(r, out)
if err != nil {
return err
}
}
// Resize events come over in bytes, need to be reserialized
resizeEvent := remotecommand.TerminalSize{}
if err := json.Unmarshal(out, &resizeEvent); err != nil {
return err
}
resize <- resizeEvent
}
case Quit:
out := make([]byte, messageSize)
if messageSize > 0 {
_, err = io.ReadFull(r, out)
if err != nil {
return err
}
}
if execEcChan != nil {
ecInt := binary.BigEndian.Uint32(out)
execEcChan <- int(ecInt)
}
return nil
case HangUpFromClient:
// This sleep allows the pipes to flush themselves before tearing everything down.
// It makes me sick to do it but after a full day I cannot put my finger on the race
// that occurs when closing things up. It would require a significant rewrite of code
// to make the pipes close down properly. Given that we are currently discussing a
// rewrite of all things remote, this hardly seems worth resolving.
//
// reproducer: echo hello | (podman-remote run -i alpine cat)
time.Sleep(1 * time.Second)
return ErrClientHangup
default:
// Something really went wrong
return errors.New("unknown multiplex destination")
}
}
}
// HangUp sends message to peer to close connection
func HangUp(writer *bufio.Writer, ec uint32) (err error) {
n := 0
msg := make([]byte, 4)
binary.BigEndian.PutUint32(msg, ec)
writeQuit := NewVirtWriteCloser(writer, Quit)
if n, err = writeQuit.Write(msg); err != nil {
return
}
if n != len(msg) {
return errors.Errorf("Failed to send complete %s message", string(msg))
}
return
}
|
