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package virtwriter
import (
"bufio"
"encoding/binary"
"encoding/json"
"errors"
"io"
"os"
"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
)
// 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
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 nil
}
// 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 *os.File, input *io.PipeWriter, resize chan remotecommand.TerminalSize) error {
var saveb []byte
var eom int
for {
readb := make([]byte, 32*1024)
n, err := r.Read(readb)
// TODO, later may be worth checking in len of the read is 0
if err != nil {
return err
}
b := append(saveb, readb[0:n]...)
// no sense in reading less than the header len
for len(b) > 7 {
eom = int(binary.BigEndian.Uint32(b[4:8])) + 8
// The message and header are togther
if len(b) >= eom {
out := append([]byte{}, b[8:eom]...)
switch IntToSocketDest(int(b[0])) {
case ToStdout:
n, err := output.Write(out)
if err != nil {
return err
}
if n < len(out) {
return errors.New("short write error occurred on stdout")
}
case ToStderr:
n, err := errput.Write(out)
if err != nil {
return err
}
if n < len(out) {
return errors.New("short write error occurred on stderr")
}
case ToStdin:
n, err := input.Write(out)
if err != nil {
return err
}
if n < len(out) {
return errors.New("short write error occurred on stdin")
}
case TerminalResize:
// 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:
return nil
}
b = b[eom:]
} else {
// We do not have the header and full message, need to slurp again
saveb = b
break
}
}
}
return nil
}
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