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#!/usr/bin/env perl
#
# Copyright (C) 2015-2019 Pierre Ossman for Cendio AB
# Copyright (C) 2009-2010 D. R. Commander. All Rights Reserved.
# Copyright (C) 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
# Copyright (C) 2002-2003 Constantin Kaplinsky. All Rights Reserved.
# Copyright (C) 2002-2005 RealVNC Ltd.
# Copyright (C) 1999 AT&T Laboratories Cambridge. All Rights Reserved.
#
# This is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This software is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this software; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
# USA.
#
#
# vncserver - wrapper script to start an X VNC server.
#
# First make sure we're operating in a sane environment.
&SanityCheck();
#
# Global variables. You may want to configure some of these for
# your site
#
$vncUserDir = rindex("$ENV{XDG_CONFIG_HOME}", "/", 0) == 0
? "$ENV{XDG_CONFIG_HOME}/tigervnc"
: "$ENV{HOME}/.config/tigervnc";
$vncLegacyDir = "$ENV{HOME}/.vnc";
if (!stat($vncUserDir) && stat($vncLegacyDir)) {
warn "~/.vnc is deprecated, please consult 'man vncsession' for paths to migrate to.";
$vncUserDir = $vncLegacyDir;
}
$vncUserConfig = "$vncUserDir/config";
$vncSystemConfigDir = "@CMAKE_INSTALL_FULL_SYSCONFDIR@/tigervnc";
$vncSystemConfigDefaultsFile = "$vncSystemConfigDir/vncserver-config-defaults";
$vncSystemConfigMandatoryFile = "$vncSystemConfigDir/vncserver-config-mandatory";
$xauthorityFile = "$ENV{XAUTHORITY}" || "$ENV{HOME}/.Xauthority";
chop($host = `uname -n`);
if (-d "/etc/X11/fontpath.d") {
$fontPath = "catalogue:/etc/X11/fontpath.d";
}
@fontpaths = ('/usr/share/X11/fonts', '/usr/share/fonts', '/usr/share/fonts/X11/');
if (! -l "/usr/lib/X11") {push(@fontpaths, '/usr/lib/X11/fonts');}
if (! -l "/usr/X11") {push(@fontpaths, '/usr/X11/lib/X11/fonts');}
if (! -l "/usr/X11R6") {push(@fontpaths, '/usr/X11R6/lib/X11/fonts');}
push(@fontpaths, '/usr/share/fonts/default');
@fonttypes = ('misc',
'75dpi',
'100dpi',
'Speedo',
'Type1');
foreach $_fpath (@fontpaths) {
foreach $_ftype (@fonttypes) {
if (-f "$_fpath/$_ftype/fonts.dir") {
if (! -l "$_fpath/$_ftype") {
$defFontPath .= "$_fpath/$_ftype,";
}
}
}
}
if ($defFontPath) {
if (substr($defFontPath, -1, 1) == ',') {
chop $defFontPath;
}
}
if ($fontPath eq "") {
$fontPath = $defFontPath;
}
# Find display number.
if ((@ARGV == 1) && ($ARGV[0] =~ /^:(\d+)$/)) {
$displayNumber = $1;
if (!&CheckDisplayNumber($displayNumber)) {
die "A VNC server is already running as :$displayNumber\n";
}
} else {
&Usage();
}
$vncPort = 5900 + $displayNumber;
$desktopName = "$host:$displayNumber ($ENV{USER})";
my %default_opts;
my %config;
# We set some reasonable defaults. Config file settings
# override these where present.
$default_opts{desktop} = $desktopName;
$default_opts{auth} = $xauthorityFile;
$default_opts{rfbauth} = "$vncUserDir/passwd";
$default_opts{rfbport} = $vncPort;
$default_opts{fp} = $fontPath if ($fontPath);
$default_opts{pn} = undef;
# Load user-overrideable system defaults
LoadConfig($vncSystemConfigDefaultsFile);
# Then the user's settings
LoadConfig($vncUserConfig);
# And then override anything set above if mandatory settings exist.
# WARNING: "Mandatory" is used loosely here! As the man page says,
# there is nothing stopping someone from EASILY subverting the
# settings in $vncSystemConfigMandatoryFile by simply passing
# CLI args to vncserver, which trump config files! To properly
# hard force policy in a non-subvertible way would require major
# development work that touches Xvnc itself.
LoadConfig($vncSystemConfigMandatoryFile, 1);
#
# Check whether VNC authentication is enabled, and if so, check that
# a VNC password has been created.
#
$securityTypeArgSpecified = 0;
$vncAuthEnabled = 0;
$passwordArgSpecified = 0;
@vncAuthStrings = ("vncauth", "tlsvnc", "x509vnc");
# ...first we check our configuration files' settings
if ($config{'securitytypes'}) {
$securityTypeArgSpecified = 1;
foreach $arg2 (split(',', $config{'securitytypes'})) {
if (grep {$_ eq lc($arg2)} @vncAuthStrings) {
$vncAuthEnabled = 1;
}
}
}
if ($config{'password'} ||
$config{'passwordfile'} ||
$config{'rfbauth'}) {
$passwordArgSpecified = 1;
}
if ((!$securityTypeArgSpecified || $vncAuthEnabled) && !$passwordArgSpecified) {
($z,$z,$mode) = stat("$vncUserDir/passwd");
if (! -e "$vncUserDir/passwd") {
die "VNC authentication enabled, but no password file created.\n";
} elsif ($mode & 077) {
die "$vncUserDir/passwd must NOT be accessible by others. Set permission to 0600.\n";
}
}
#
# Find a desktop session to run
#
my $sessionname;
my %session;
$sessionname = delete $config{'session'};
if ($sessionname) {
%session = LoadXSession($sessionname);
if (!%session) {
warn "Could not load configured desktop session $sessionname\n";
$sessionname = undef;
}
}
if (!$sessionname) {
foreach $file (glob("/usr/share/xsessions/*.desktop")) {
($name) = $file =~ /^.*\/(.*)[.]desktop$/;
%session = LoadXSession($name);
if (%session) {
$sessionname = $name;
last;
}
}
}
if (!$sessionname) {
die "Could not find a desktop session to run\n";
}
warn "Using desktop session $sessionname\n";
if (!$session{'Exec'}) {
die "No command specified for desktop session\n";
}
$ENV{GDMSESSION} = $sessionname;
$ENV{DESKTOP_SESSION} = $sessionname;
$ENV{XDG_SESSION_DESKTOP} = $sessionname;
if ($session{'DesktopNames'}) {
$ENV{XDG_CURRENT_DESKTOP} = $session{'DesktopNames'} =~ s/;/:/gr;
}
# Make an X server cookie and set up the Xauthority file
# mcookie is a part of util-linux, usually only GNU/Linux systems have it.
$cookie = `mcookie`;
# Fallback for non GNU/Linux OS - use /dev/urandom on systems that have it,
# otherwise use perl's random number generator, seeded with the sum
# of the current time, our PID and part of the encrypted form of the password.
if ($cookie eq "" && open(URANDOM, '<', '/dev/urandom')) {
my $randata;
if (sysread(URANDOM, $randata, 16) == 16) {
$cookie = unpack 'h*', $randata;
}
close(URANDOM);
}
if ($cookie eq "") {
srand(time+$$+unpack("L",`cat $vncUserDir/passwd`));
for (1..16) {
$cookie .= sprintf("%02x", int(rand(256)) % 256);
}
}
open(XAUTH, "|xauth -f $xauthorityFile source -");
print XAUTH "add $host:$displayNumber . $cookie\n";
print XAUTH "add $host/unix:$displayNumber . $cookie\n";
close(XAUTH);
$ENV{XAUTHORITY} = $xauthorityFile;
# Now start the X VNC server
@cmd = ("xinit");
push(@cmd, $Xsession, $session{'Exec'});
push(@cmd, '--');
# We build up our Xvnc command with options
push(@cmd, "@CMAKE_INSTALL_FULL_BINDIR@/Xvnc", ":$displayNumber");
foreach my $k (sort keys %config) {
push(@cmd, "-$k");
push(@cmd, $config{$k}) if defined($config{$k});
delete $default_opts{$k}; # file options take precedence
}
foreach my $k (sort keys %default_opts) {
push(@cmd, "-$k");
push(@cmd, $default_opts{$k}) if defined($default_opts{$k});
}
warn "\nNew '$desktopName' desktop is $host:$displayNumber\n\n";
warn "Starting desktop session $sessionname\n";
exec(@cmd);
die "Failed to start session.\n";
###############################################################################
# Functions
###############################################################################
#
# Populate the global %config hash with settings from a specified
# vncserver configuration file if it exists
#
# Args: 1. file path
# 2. optional boolean flag to enable warning when a previously
# set configuration setting is being overridden
#
sub LoadConfig {
local ($configFile, $warnoverride) = @_;
local ($toggle) = undef;
if (stat($configFile)) {
if (open(IN, $configFile)) {
while (<IN>) {
next if /^#/;
if (my ($k, $v) = /^\s*(\w+)\s*=\s*(.*)$/) {
$k = lc($k); # must normalize key case
if ($warnoverride && $config{$k}) {
print("Warning: $configFile is overriding previously defined '$k' to be '$v'\n");
}
$config{$k} = $v;
} elsif ($_ =~ m/^\s*(\S+)/) {
# We can't reasonably warn on override of toggles (e.g. AlwaysShared)
# because it would get crazy to do so. We'd have to check if the
# current config file being loaded defined the logical opposite setting
# (NeverShared vs. AlwaysShared, etc etc).
$toggle = lc($1); # must normalize key case
$config{$toggle} = undef;
}
}
close(IN);
}
}
}
#
# Load a session desktop file
#
sub LoadXSession {
local ($name) = @_;
my $file, $found_group, %session;
$file = "/usr/share/xsessions/$name.desktop";
if (!stat($file)) {
warn "Could not find session desktop file $file";
return;
}
if (!open(IN, $file)) {
warn "Could not open session desktop file $file";
return;
}
$found_group = 0;
while (my $line = <IN>) {
next if $line =~ /^#/;
next if $line =~ /^\s*$/;
if (!$found_group) {
next if $line != "[Desktop Entry]";
$found_group = 1;
next;
} else {
last if $line =~ /^\[/;
}
my ($key, $value) = $line =~ /^\s*([]A-Za-z0-9_@\-\[]+)\s*=\s*(.*)$/;
if (!$key) {
warn "Invalid session desktop file $file";
close(IN);
return;
}
$value =~ s/\\s/ /g;
$value =~ s/\\n/\n/g;
$value =~ s/\\t/\t/g;
$value =~ s/\\r/\r/g;
$value =~ s/\\\\/\\/g;
$session{$key} = $value;
}
close(IN);
return %session;
}
#
# CheckDisplayNumber checks if the given display number is available. A
# display number n is taken if something is listening on the VNC server port
# (5900+n) or the X server port (6000+n).
#
sub CheckDisplayNumber
{
my($n) = @_;
use Socket;
my $x11_lock_path = "/tmp/.X$n-lock";
if (-e $x11_lock_path) {
my($pid) = `cat "$x11_lock_path"` =~ /^\s*(\d+)\s*$/;
if (defined($pid) && kill(0, $pid)) {
# Lock is associated with valid PID.
return 0;
}
}
my $rfb_port = 5900 + $n;
my $x11_port = 6000 + $n;
for my $port ($rfb_port, $x11_port) {
# Bind to port to confirm it is not in use.
socket(S, PF_INET, SOCK_STREAM, 0) || die "$prog: socket failed: $!\n";
setsockopt(S, SOL_SOCKET, SO_REUSEADDR, 1);
if (!bind(S, sockaddr_in($port, INADDR_ANY))) {
# Port is in use.
close(S);
return 0;
}
close(S);
}
my $x11_unix_domain = "/tmp/.X11-unix/X$n";
if (-e $x11_unix_domain) {
# Connect to UNIX domain socket to confirm it is not in use.
socket(S, PF_UNIX, SOCK_STREAM, 0) || die "$prog: socket failed: $!\n";
if (connect(S, sockaddr_un($x11_unix_domain))) {
# UNIX domain socket is in use.
close(S);
return 0;
}
close(S);
}
return 1;
}
#
# Usage
#
sub Usage
{
die("\nusage: $prog <display>\n\n");
}
# Routine to make sure we're operating in a sane environment.
sub SanityCheck
{
local ($cmd);
# Get the program name
($prog) = ($0 =~ m|([^/]+)$|);
#
# Check we have all the commands we'll need on the path.
#
cmd:
foreach $cmd ("uname","xauth","xinit") {
for (split(/:/,$ENV{PATH})) {
if (-x "$_/$cmd") {
next cmd;
}
}
die "$prog: couldn't find \"$cmd\" on your PATH.\n";
}
foreach $cmd ("/etc/X11/xinit/Xsession", "/etc/X11/Xsession") {
if (-x "$cmd") {
$Xsession = $cmd;
last;
}
}
if (not defined $Xsession) {
die "$prog: Couldn't find suitable Xsession.\n";
}
if (!defined($ENV{HOME})) {
die "$prog: The HOME environment variable is not set.\n";
}
}
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