summaryrefslogtreecommitdiff
path: root/pkg/varlinkapi/virtwriter/virtwriter.go
blob: 3adaf6e17148177456b29e503e50bd8fa8cc145f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
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
}