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package xgb
/*
conn.go contains a couple of functions that do some real dirty work related
to the initial connection handshake with X.
This code is largely unmodified from the original XGB package that I forked.
*/
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))
}
// Unfortunately, it isn't really feasible to read the setup bytes here,
// since the code to do so is in a different package.
// Users must call 'xproto.Setup(X)' to get the setup info.
c.SetupBytes = buf
// But also read stuff that we *need* to get started.
c.setupResourceIdBase = Get32(buf[12:])
c.setupResourceIdMask = Get32(buf[16:])
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:]
}
var err error
c.DisplayNumber, err = strconv.Atoi(c.display)
if err != nil || c.DisplayNumber < 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+c.DisplayNumber))
} 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
}
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