【脚本语言】VNC Server 启动脚本分析

#!/usr/bin/perl
#
# vncserver - wrapper script to start an X VNC server.
#

# First make sure we're operating in a sane environment.

&SanityCheck();

# Default configuration of the TightVNC Server:

$geometry = "1024x768";
$depth = 24;
$desktopName = "X";
$vncClasses = "/usr/local/vnc/classes";
$vncUserDir = "$ENV{HOME}/.vnc";
$fontPath = "unix/:7100";
$authType = "-rfbauth $vncUserDir/passwd";

# Read configuration from the system-wide and user files if present.

$configFile = "/etc/tightvncserver.conf";
ReadConfiguration();
$configFile = "$ENV{HOME}/.vnc/tightvncserver.conf";
ReadConfiguration();

# Done reading configuration.

$defaultXStartup
    = ("#!/bin/sh\n\n".
       "xrdb \$HOME/.Xresources\n".
       "xsetroot -solid grey\n".
       "xterm -geometry 80x24+10+10 -ls -title \"\$VNCDESKTOP Desktop\" &\n".
       "twm &\n");

$xauthorityFile = "$ENV{XAUTHORITY}";

$vncUserDirUnderTmp = ($vncUserDir =~ m|^/tmp/.+|) ? 1 : 0;
$xstartup = ($vncUserDirUnderTmp) ?
  "$ENV{HOME}/.vncstartup" : "$vncUserDir/xstartup";
unless ($xauthorityFile) {
    if ($vncUserDirUnderTmp) {
        $xauthorityFile = "$vncUserDir/.Xauthority";
    } else {
        $xauthorityFile = "$ENV{HOME}/.Xauthority";
    }
}

chop($host = `uname -n`);

# Check command line options

&ParseOptions("-geometry",1,"-depth",1,"-pixelformat",1,"-name",1,"-kill",1,
       "-help",0,"-h",0,"--help",0);

&Usage() if ($opt{'-help'} || $opt{'-h'} || $opt{'--help'});

&Kill() if ($opt{'-kill'});

# Uncomment this line if you want default geometry, depth and pixelformat
# to match the current X display:
# &GetXDisplayDefaults();

if ($opt{'-geometry'}) {
    $geometry = $opt{'-geometry'};
}
if ($opt{'-depth'}) {
    $depth = $opt{'-depth'};
    $pixelformat = "";
}
if ($opt{'-pixelformat'}) {
    $pixelformat = $opt{'-pixelformat'};
}

&CheckGeometryAndDepth();

if ($opt{'-name'}) {
    $desktopName = $opt{'-name'};
}

# Create the user's vnc directory if necessary.

unless (-e $vncUserDir) {
    unless (mkdir($vncUserDir, 0700)) {
        die "$prog: Could not create $vncUserDir.\n";
    }
}
($z,$z,$mode) = lstat("$vncUserDir");
if (!-d _ || !-o _ || ($vncUserDirUnderTmp && ($mode & 0777) != 0700)) {
    die "$prog: Wrong type or access mode of $vncUserDir.\n";
}

# Make sure the user has a password.

($z,$z,$mode) = lstat("$vncUserDir/passwd");
if (-e _ && (!-f _ || !-o _)) {
    die "$prog: Wrong type or ownership on $vncUserDir/passwd.\n";
}
if (!-e _ || ($mode & 077) != 0) {
    warn "\nYou will require a password to access your desktops.\n\n";
    system("vncpasswd $vncUserDir/passwd");
    if (($? & 0xFF00) != 0) {
        exit 1;
    }
}

# Find display number.

if ((@ARGV > 0) && ($ARGV[0] =~ /^:(\d+)$/)) {
    $displayNumber = $1;
    shift(@ARGV);
    unless (&CheckDisplayNumber($displayNumber)) {
 die "A VNC server is already running as :$displayNumber\n";
    }
} elsif ((@ARGV > 0) && ($ARGV[0] !~ /^-/)) {
    &Usage();
} else {
    $displayNumber = &GetDisplayNumber();
}

$vncPort = 5900 + $displayNumber;

$desktopLog = "$vncUserDir/$host:$displayNumber.log";
unlink($desktopLog);

# Make an X server cookie - use as the seed the sum of the current time, our
# PID and part of the encrypted form of the password.  Ideally we'd use
# /dev/urandom, but that's only available on Linux.

srand(time+$$+unpack("L",`cat $vncUserDir/passwd`));
$cookie = "";
for (1..16) {
    $cookie .= sprintf("%02x", int(rand(256)));
}

system("xauth -f $xauthorityFile add $host:$displayNumber . $cookie");
system("xauth -f $xauthorityFile add $host/unix:$displayNumber . $cookie");

# Now start the X VNC Server

$cmd = "Xvnc :$displayNumber";
$cmd .= " -desktop " . "edString($desktopName);
$cmd .= " -httpd $vncClasses";
$cmd .= " -auth $xauthorityFile";
$cmd .= " -geometry $geometry" if ($geometry);
$cmd .= " -depth $depth" if ($depth);
$cmd .= " -pixelformat $pixelformat" if ($pixelformat);
$cmd .= " -rfbwait 120000";
$cmd .= " $authType";
$cmd .= " -rfbport $vncPort";
$cmd .= " -fp $fontPath" if ($fontPath);
$cmd .= " -co $colorPath" if ($colorPath);

foreach $arg (@ARGV) {
    $cmd .= " " . "edString($arg);
}
$cmd .= " >> " . "edString($desktopLog) . " 2>&1";

# Run $cmd and record the process ID.

$pidFile = "$vncUserDir/$host:$displayNumber.pid";
system("$cmd & echo \$! >$pidFile");

# Give Xvnc a chance to start up

sleep(1);
unless (kill 0, `cat $pidFile`) {
    warn "Couldn't start Xvnc; trying default font path.\n";
    warn "Please set correct fontPath in the $prog script.\n";
    $cmd =~ [^ ]+@@;
    system("$cmd & echo \$! >$pidFile");
    sleep(1);
}
unless (kill 0, `cat $pidFile`) {
    warn "Couldn't start Xvnc process.\n\n";
    open(LOG, "<$desktopLog");
    while () { print; }
    close(LOG);
    die "\n";
}

warn "\nNew '$desktopName' desktop is $host:$displayNumber\n\n";

# Create the user's xstartup script if necessary.

unless (-e "$xstartup") {
    warn "Creating default startup script $xstartup\n";
    open(XSTARTUP, ">$xstartup");
    print XSTARTUP $defaultXStartup;
    close(XSTARTUP);
    chmod 0755, "$xstartup";
}

# Run the X startup script.

warn "Starting applications specified in $xstartup\n";
warn "Log file is $desktopLog\n\n";

# If the unix domain socket exists then use that (DISPLAY=:n) otherwise use
# TCP (DISPLAY=host:n)

if (-e "/tmp/.X11-unix/X$displayNumber") {
    $ENV{DISPLAY}= ":$displayNumber";
} else {
    $ENV{DISPLAY}= "$host:$displayNumber";
}
$ENV{VNCDESKTOP}= $desktopName;

system("$xstartup >> " . "edString($desktopLog) . " 2>&1 &");

exit;

###############################################################################
#
# CheckGeometryAndDepth simply makes sure that the geometry and depth values
# are sensible.
#

sub CheckGeometryAndDepth
{
    if ($geometry =~ /^(\d+)x(\d+)$/) {
 $width = $1; $height = $2;

 if (($width<1) || ($height<1)) {
     die "$prog: geometry $geometry is invalid\n";
 }

 while (($width % 4)!=0) {
     $width = $width + 1;
 }

 while (($height % 2)!=0) {
     $height = $height + 1;
 }

 $geometry = "${width}x$height";
    } else {
 die "$prog: geometry $geometry is invalid\n";
    }

    if (($depth < 8) || ($depth > 32)) {
 die "Depth must be between 8 and 32\n";
    }
}

#
# GetDisplayNumber gets the lowest available display number.  A display number
# n is taken if something is listening on the VNC server port (5900+n) or the
# X server port (6000+n).
#

sub GetDisplayNumber
{
    foreach $n (1..99) {
 if (&CheckDisplayNumber($n)) {
     return $n+0; # Bruce Mah's workaround for bug in perl 5.005_02
 }
    }
   
    die "$prog: no free display number on $host.\n";
}

#
# CheckDisplayNumber checks if the given display number is available.  A
# display number n is taken if something is listening on the VNC server port
# (5900+n) or the X server port (6000+n).
#

sub CheckDisplayNumber
{
    local ($n) = @_;

    socket(S, $AF_INET, $SOCK_STREAM, 0) || die "$prog: socket failed: $!\n";
    eval 'setsockopt(S, &SOL_SOCKET, &SO_REUSEADDR, pack("l", 1))';
    unless (bind(S, pack('S n x12', $AF_INET, 6000 + $n))) {
 close(S);
 return 0;
    }
    close(S);

    socket(S, $AF_INET, $SOCK_STREAM, 0) || die "$prog: socket failed: $!\n";
    eval 'setsockopt(S, &SOL_SOCKET, &SO_REUSEADDR, pack("l", 1))';
    unless (bind(S, pack('S n x12', $AF_INET, 5900 + $n))) {
 close(S);
 return 0;
    }
    close(S);

    if (-e "/tmp/.X$n-lock") {
 warn "\nWarning: $host:$n is taken because of /tmp/.X$n-lock\n";
 warn "Remove this file if there is no X server $host:$n\n";
 return 0;
    }

    if (-e "/tmp/.X11-unix/X$n") {
 warn "\nWarning: $host:$n is taken because of /tmp/.X11-unix/X$n\n";
 warn "Remove this file if there is no X server $host:$n\n";
 return 0;
    }

    return 1;
}

#
# GetXDisplayDefaults uses xdpyinfo to find out the geometry, depth and pixel
# format of the current X display being used.  If successful, it sets the
# options as appropriate so that the X VNC server will use the same settings
# (minus an allowance for window manager decorations on the geometry).  Using
# the same depth and pixel format means that the VNC server won't have to
# translate pixels when the desktop is being viewed on this X display (for
# TrueColor displays anyway).
#

sub GetXDisplayDefaults
{
    local (@lines, @matchlines, $width, $height, $defaultVisualId, $i,
    $red, $green, $blue);

    $wmDecorationWidth = 4; # a guess at typical size for window manager
    $wmDecorationHeight = 24; # decoration size

    return unless (defined($ENV{DISPLAY}));

    @lines = `xdpyinfo 2>/dev/null`;

    return if ($? != 0);

    @matchlines = grep(/dimensions/, @lines);
    if (@matchlines) {
 ($width, $height) = ($matchlines[0] =~ /(\d+)x(\d+) pixels/);

 $width -= $wmDecorationWidth;
 $height -= $wmDecorationHeight;

 $geometry = "${width}x$height";
    }

    @matchlines = grep(/default visual id/, @lines);
    if (@matchlines) {
 ($defaultVisualId) = ($matchlines[0] =~ /id:\s+(\S+)/);

 for ($i = 0; $i < @lines; $i++) {
     if ($lines[$i] =~ /^\s*visual id:\s+$defaultVisualId$/) {
  if (($lines[$i+1] !~ /TrueColor/) ||
      ($lines[$i+2] !~ /depth/) ||
      ($lines[$i+4] !~ /red, green, blue masks/))
  {
      return;
  }
  last;
     }
 }

 return if ($i >= @lines);

 ($depth) = ($lines[$i+2] =~ /depth:\s+(\d+)/);
 ($red,$green,$blue)
     = ($lines[$i+4]
        =~ /masks:\s+0x([0-9a-f]+), 0x([0-9a-f]+), 0x([0-9a-f]+)/);

 $red = hex($red);
 $green = hex($green);
 $blue = hex($blue);

 if ($red > $blue) {
     $red = int(log($red) / log(2)) - int(log($green) / log(2));
     $green = int(log($green) / log(2)) - int(log($blue) / log(2));
     $blue = int(log($blue) / log(2)) + 1;
     $pixelformat = "rgb$red$green$blue";
 } else {
     $blue = int(log($blue) / log(2)) - int(log($green) / log(2));
     $green = int(log($green) / log(2)) - int(log($red) / log(2));
     $red = int(log($red) / log(2)) + 1;
     $pixelformat = "bgr$blue$green$red";
 }
    }
}

#
# quotedString returns a string which yields the original string when parsed
# by a shell.
#

sub quotedString
{
    local ($in) = @_;

    $in =~ s/\'/\'\"\'\"\'/g;

    return "'$in'";
}

#
# removeSlashes turns slashes into underscores for use as a file name.
#

sub removeSlashes
{
    local ($in) = @_;

    $in =~ s|/|_|g;

    return "$in";
}

#
# Usage
#

sub Usage
{
    die("TightVNC Server version 1.3.10\n".
 "\n".
 "Usage: $prog [] [:]\n".
 "       $prog -kill :\n".
 "\n".
 " are Xvnc options, or:\n".
 "\n".
 "        -name \n".
 "        -depth \n".
 "        -geometry x\n".
 "        -pixelformat rgb\n".
 "        -pixelformat bgr\n".
 "\n".
 "See vncserver and Xvnc manual pages for more information.\n");
}

#
# Kill
#

sub Kill
{
    $opt{'-kill'} =~ s/(:\d+)\.\d+$/$1/; # e.g. turn :1.0 into :1

    if ($opt{'-kill'} =~ /^:\d+$/) {
 $pidFile = "$vncUserDir/$host$opt{'-kill'}.pid";
    } else {
 if ($opt{'-kill'} !~ /^$host:/) {
     die "\nCan't tell if $opt{'-kill'} is on $host\n".
  "Use -kill : instead\n\n";
 }
 $pidFile = "$vncUserDir/$opt{'-kill'}.pid";
    }

    unless (-r $pidFile) {
 die "\nCan't find file $pidFile\n".
     "You'll have to kill the Xvnc process manually\n\n";
    }

    $SIG{'HUP'} = 'IGNORE';
    chop($pid = `cat $pidFile`);
    warn "Killing Xvnc process ID $pid\n";
    system("kill $pid");
    unlink $pidFile;
    exit;
}

#
# ParseOptions takes a list of possible options and a boolean indicating
# whether the option has a value following, and sets up an associative array
# %opt of the values of the options given on the command line. It removes all
# the arguments it uses from @ARGV and returns them in @optArgs.
#

sub ParseOptions
{
    local (@optval) = @_;
    local ($opt, @opts, %valFollows, @newargs);

    while (@optval) {
 $opt = shift(@optval);
 push(@opts,$opt);
 $valFollows{$opt} = shift(@optval);
    }

    @optArgs = ();
    %opt = ();

    arg: while (defined($arg = shift(@ARGV))) {
 foreach $opt (@opts) {
     if ($arg eq $opt) {
  push(@optArgs, $arg);
  if ($valFollows{$opt}) {
      if (@ARGV == 0) {
   &Usage();
      }
      $opt{$opt} = shift(@ARGV);
      push(@optArgs, $opt{$opt});
  } else {
      $opt{$opt} = 1;
  }
  next arg;
     }
 }
 push(@newargs,$arg);
    }

    @ARGV = @newargs;
}

#
# Routine to make sure we're operating in a sane environment.
#

sub SanityCheck
{
    local ($cmd);

    #
    # Get the program name
    #

    ($prog) = ($0 =~ m|([^/]+)$|);

    #
    # Check we have all the commands we'll need on the path.
    #

 cmd:
    foreach $cmd ("uname","xauth","Xvnc","vncpasswd") {
 for (split(/:/,$ENV{PATH})) {
     if (-x "$_/$cmd") {
  next cmd;
     }
 }
 die "$prog: couldn't find \"$cmd\" on your PATH.\n";
    }

    #
    # Check the HOME and USER environment variables are both set.
    #

    unless (defined($ENV{HOME})) {
 die "$prog: The HOME environment variable is not set.\n";
    }
    unless (defined($ENV{USER})) {
 die "$prog: The USER environment variable is not set.\n";
    }

    #
    # Find socket constants. 'use Socket' is a perl5-ism, so we wrap it in an
    # eval, and if it fails we try 'require "sys/socket.ph"'.  If this fails,
    # we just guess at the values.  If you find perl moaning here, just
    # hard-code the values of AF_INET and SOCK_STREAM.  You can find these out
    # for your platform by looking in /usr/include/sys/socket.h and related
    # files.
    #

    chop($os = `uname`);
    chop($osrev = `uname -r`);

    eval 'use Socket';
    if ($@) {
 eval 'require "sys/socket.ph"';
 if ($@) {
     if (($os eq "SunOS") && ($osrev !~ /^4/)) {
  $AF_INET = 2;
  $SOCK_STREAM = 2;
     } else {
  $AF_INET = 2;
  $SOCK_STREAM = 1;
     }
 } else {
     $AF_INET = &AF_INET;
     $SOCK_STREAM = &SOCK_STREAM;
 }
    } else {
 $AF_INET = &AF_INET;
 $SOCK_STREAM = &SOCK_STREAM;
    }
}

sub ReadConfiguration
{
  my @configurableVariables =
    qw(geometry
       depth
       desktopName
       vncClasses
       vncUserDir
       fontPath
       authType
       colorPath
      );

  if (open CONF, "<$configFile") {
    while () {
      if (/^\s*\$(\w+)\s*=\s*(.*)$/) {
        for my $var (@configurableVariables) {
          if ($1 eq $var) {
            eval $_;
            last;
          }
        }
      }
    }
    close CONF;
  }
}