aboutsummaryrefslogtreecommitdiff
path: root/nexgb/conn.go
blob: af78be954a16176463941359eee7195907ec3733 (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
156
157
158
159
160
161
162
package xgb

import (
	"errors"
	"fmt"
	"io"
	"net"
	"os"
	"strconv"
	"strings"
)

// connect connects to the X server given in the 'display' string,
// and does all the necessary setup handshaking.
// If 'display' is empty it will be taken from os.Getenv("DISPLAY").
// Note that you should read and understand the "Connection Setup" of the
// X Protocol Reference Manual before changing this function:
// http://goo.gl/4zGQg
func (c *Conn) connect(display string) error {
	err := c.dial(display)
	if err != nil {
		return err
	}

	// Get authentication data
	authName, authData, err := readAuthority(c.host, c.display)
	noauth := false
	if err != nil {
		logger.Printf("Could not get authority info: %v", err)
		logger.Println("Trying connection without authority info...")
		authName = ""
		authData = []byte{}
		noauth = true
	}

	// Assume that the authentication protocol is "MIT-MAGIC-COOKIE-1".
	if !noauth && (authName != "MIT-MAGIC-COOKIE-1" || len(authData) != 16) {
		return errors.New("unsupported auth protocol " + authName)
	}

	buf := make([]byte, 12+pad(len(authName))+pad(len(authData)))
	buf[0] = 0x6c
	buf[1] = 0
	Put16(buf[2:], 11)
	Put16(buf[4:], 0)
	Put16(buf[6:], uint16(len(authName)))
	Put16(buf[8:], uint16(len(authData)))
	Put16(buf[10:], 0)
	copy(buf[12:], []byte(authName))
	copy(buf[12+pad(len(authName)):], authData)
	if _, err = c.conn.Write(buf); err != nil {
		return err
	}

	head := make([]byte, 8)
	if _, err = io.ReadFull(c.conn, head[0:8]); err != nil {
		return err
	}
	code := head[0]
	reasonLen := head[1]
	major := Get16(head[2:])
	minor := Get16(head[4:])
	dataLen := Get16(head[6:])

	if major != 11 || minor != 0 {
		return fmt.Errorf("x protocol version mismatch: %d.%d", major, minor)
	}

	buf = make([]byte, int(dataLen)*4+8, int(dataLen)*4+8)
	copy(buf, head)
	if _, err = io.ReadFull(c.conn, buf[8:]); err != nil {
		return err
	}

	if code == 0 {
		reason := buf[8 : 8+reasonLen]
		return fmt.Errorf("x protocol authentication refused: %s",
			string(reason))
	}

	ReadSetupInfo(buf, &c.Setup)

	if c.defaultScreen >= len(c.Setup.Roots) {
		c.defaultScreen = 0
	}

	return nil
}

// dial initializes the actual net connection with X.
func (c *Conn) dial(display string) error {
	if len(display) == 0 {
		display = os.Getenv("DISPLAY")
	}

	display0 := display
	if len(display) == 0 {
		return errors.New("empty display string")
	}

	colonIdx := strings.LastIndex(display, ":")
	if colonIdx < 0 {
		return errors.New("bad display string: " + display0)
	}

	var protocol, socket string

	if display[0] == '/' {
		socket = display[0:colonIdx]
	} else {
		slashIdx := strings.LastIndex(display, "/")
		if slashIdx >= 0 {
			protocol = display[0:slashIdx]
			c.host = display[slashIdx+1 : colonIdx]
		} else {
			c.host = display[0:colonIdx]
		}
	}

	display = display[colonIdx+1 : len(display)]
	if len(display) == 0 {
		return errors.New("bad display string: " + display0)
	}

	var scr string
	dotIdx := strings.LastIndex(display, ".")
	if dotIdx < 0 {
		c.display = display[0:]
	} else {
		c.display = display[0:dotIdx]
		scr = display[dotIdx+1:]
	}

	dispnum, err := strconv.Atoi(c.display)
	if err != nil || dispnum < 0 {
		return errors.New("bad display string: " + display0)
	}

	if len(scr) != 0 {
		c.defaultScreen, err = strconv.Atoi(scr)
		if err != nil {
			return errors.New("bad display string: " + display0)
		}
	}

	// Connect to server
	if len(socket) != 0 {
		c.conn, err = net.Dial("unix", socket+":"+c.display)
	} else if len(c.host) != 0 {
		if protocol == "" {
			protocol = "tcp"
		}
		c.conn, err = net.Dial(protocol, c.host+":"+strconv.Itoa(6000+dispnum))
	} else {
		c.conn, err = net.Dial("unix", "/tmp/.X11-unix/X"+c.display)
	}

	if err != nil {
		return errors.New("cannot connect to " + display0 + ": " + err.Error())
	}
	return nil
}