Revise paste Start Powershell Webserver

<#
.Synopsis
Starts powershell webserver
.Description
Starts webserver as powershell process.
Call of the root page (e.g. http://localhost:8080/) returns a powershell execution web form.
Call of /script uploads a powershell script and executes it (as a function).
Call of /log returns the webserver logs, /starttime the start time of the webserver, /time the current time.
/download downloads and /upload uploads a file. /beep generates a sound and /quit or /exit stops the webserver.

You may have to configure a firewall exception to allow access to the chosen port, e.g. with:
  netsh advfirewall firewall add rule name="Powershell Webserver" dir=in action=allow protocol=TCP localport=8080

After stopping the webserver you should remove the rule, e.g.:
  netsh advfirewall firewall delete rule name="Powershell Webserver"
.Parameter BINDING
Binding of the webserver
.Inputs
None
.Outputs
None
.Example
Start-Webserver.ps1

Starts webserver with binding to http://localhost:8080/
.Example
Start-Webserver.ps1 "http://+:8080/"

Starts webserver with binding to all IP addresses of the system.
Administrative rights are necessary.
.Example
schtasks.exe /Create /TN "Powershell Webserver" /TR "powershell -file C:\Users\Markus\Documents\Start-WebServer.ps1 http://+:8080/" /SC ONSTART /RU SYSTEM /RL HIGHEST /F

Starts powershell webserver as scheduled task as user local system every time the computer starts (when the
correct path to the file Start-WebServer.ps1 is given).
You can start the webserver task manually with
  schtasks.exe /Run /TN "Powershell Webserver"
Delete the webserver task with
  schtasks.exe /Delete /TN "Powershell Webserver"
Scheduled tasks are always running with low priority, so some functions might be slow.
.Notes
Author: Markus Scholtes, 2016-10-22
#>
Param([STRING]$BINDING = 'http://localhost:8080/')

# No adminstrative permissions are required for a binding to "localhost"
# $BINDING = 'http://localhost:8080/'
# Adminstrative permissions are required for a binding to network names or addresses.
# + takes all requests to the port regardless of name or ip, * only requests that no other listener answers:
# $BINDING = 'http://+:8080/'

# HTML answer templates for specific calls, placeholders !RESULT, !FORMFIELD, !PROMPT are allowed
$HTMLRESPONSECONTENTS = @{
  'GET /'  =  @"
<html><body>
	!HEADERLINE
	<pre>!RESULT</pre>
	<form method="GET" action="/">
	<b>!PROMPT </b><input type="text" maxlength=255 size=80 name="command" value='!FORMFIELD'>
  <input type="submit" name="button" value="Enter">
	</form>
</body></html>
"@
  'GET /script'  =  @"
<html><body>
	!HEADERLINE
	<form method="POST" enctype="multipart/form-data" action="/script">
	<p><b>Script to execute:</b><input type="file" name="filedata"></p>
	<b>Parameters:</b><input type="text" maxlength=255 size=80 name="parameter">
  <input type="submit" name="button" value="Execute">
	</form>
</body></html>
"@
  'GET /download'  =  @"
<html><body>
	!HEADERLINE
	<pre>!RESULT</pre>
	<form method="POST" action="/download">
	<b>Path to file:</b><input type="text" maxlength=255 size=80 name="filepath" value='!FORMFIELD'>
  <input type="submit" name="button" value="Download">
	</form>
</body></html>
"@
  'POST /download'  =  @"
<html><body>
	!HEADERLINE
	<pre>!RESULT</pre>
	<form method="POST" action="/download">
	<b>Path to file:</b><input type="text" maxlength=255 size=80 name="filepath" value='!FORMFIELD'>
  <input type="submit" name="button" value="Download">
	</form>
</body></html>
"@
  'GET /upload'  =  @"
<html><body>
	!HEADERLINE
	<form method="POST" enctype="multipart/form-data" action="/upload">
	<p><b>File to upload:</b><input type="file" name="filedata"></p>
	<b>Path to store on webserver:</b><input type="text" maxlength=255 size=80 name="filepath">
  <input type="submit" name="button" value="Upload">
	</form>
</body></html>
"@
  'POST /script' = "<html><body>!HEADERLINE<pre>!RESULT</pre></body></html>"
  'POST /upload' = "<html><body>!HEADERLINE<pre>!RESULT</pre></body></html>"
  'GET /exit' = "<html><body>Stopped powershell webserver</body></html>"
  'GET /quit' = "<html><body>Stopped powershell webserver</body></html>"
  'GET /log' = "<html><body>!HEADERLINELog of powershell webserver:<br /><pre>!RESULT</pre></body></html>"
  'GET /starttime' = "<html><body>!HEADERLINEPowershell webserver started at $(Get-Date -Format s)</body></html>"
  'GET /time' = "<html><body>!HEADERLINECurrent time: !RESULT</body></html>"
  'GET /beep' = "<html><body>!HEADERLINEBEEP...</body></html>"
}

# Set navigation header line for all web pages
$HEADERLINE = "<p><a href='/'>Command execution</a> <a href='/script'>Execute script</a> <a href='/download'>Download file</a> <a href='/upload'>Upload file</a> <a href='/log'>Web logs</a> <a href='/starttime'>Webserver start time</a> <a href='/time'>Current time</a> <a href='/beep'>Beep</a> <a href='/quit'>Stop webserver</a></p>"

# Starting the powershell webserver
"$(Get-Date -Format s) Starting powershell webserver..."
$LISTENER = New-Object System.Net.HttpListener
$LISTENER.Prefixes.Add($BINDING)
$LISTENER.Start()
$Error.Clear()

try
{
	"$(Get-Date -Format s) Powershell webserver started."
	$WEBLOG = "$(Get-Date -Format s) Powershell webserver started.`n"
  while ($LISTENER.IsListening)
  {
    # analyze incoming request
    $CONTEXT = $LISTENER.GetContext()
    $REQUEST = $CONTEXT.Request
    $RESPONSE = $CONTEXT.Response
    $RESPONSEWRITTEN = $FALSE

# log to console
    "$(Get-Date -Format s) $($REQUEST.RemoteEndPoint.Address.ToString()) $($REQUEST.httpMethod) $($REQUEST.Url.PathAndQuery)"
    # and in log variable
    $WEBLOG += "$(Get-Date -Format s) $($REQUEST.RemoteEndPoint.Address.ToString()) $($REQUEST.httpMethod) $($REQUEST.Url.PathAndQuery)`n"

# is there a fixed coding for the request?
    $RECEIVED = '{0} {1}' -f $REQUEST.httpMethod, $REQUEST.Url.LocalPath
    $HTMLRESPONSE = $HTMLRESPONSECONTENTS[$RECEIVED]
	  $RESULT = ''

# check for known commands
    switch ($RECEIVED)
    {
      "GET /"
      {	# execute command
	  		# retrieve GET query string
	  		$FORMFIELD = ''
	    	$FORMFIELD = [URI]::UnescapeDataString(($REQUEST.Url.Query -replace "\+"," "))
	    	# remove fixed form fields out of query string
	    	$FORMFIELD = $FORMFIELD -replace "\?command=","" -replace "\?button=enter","" -replace "&command=","" -replace "&button=enter",""
	    	# when command is given...
    		if (![STRING]::IsNullOrEmpty($FORMFIELD))
	   		{
		    	try {
		    		# ... execute command
		    		$RESULT = Invoke-Expression -EA SilentlyContinue $FORMFIELD 2> $NULL | Out-String
		    	}
		    	catch	{}
		    	if ($Error.Count -gt 0)
		    	{ # retrieve error message on error
		    		$RESULT += "`nError while executing '$FORMFIELD'`n`n"
		    		$RESULT += $Error[0]
		    		$Error.Clear()
		    	}
	    	}
	    	# preset form value with command for the caller's convenience
   			$HTMLRESPONSE = $HTMLRESPONSE -replace '!FORMFIELD', $FORMFIELD
   			# insert powershell prompt to form
	  		$PROMPT = "PS $PWD>"
   			$HTMLRESPONSE = $HTMLRESPONSE -replace '!PROMPT', $PROMPT
        break
      }

"GET /script"
      { # present upload form, nothing to do here
      	break
      }

"POST /script"
      { # upload and execute script

# only if there is body data in the request
      	if ($REQUEST.HasEntityBody)
      	{
      		# set default message to error message (since we just stop processing on error)
      		$RESULT = "Received corrupt or incomplete form data"

# check content type
      		if ($REQUEST.ContentType)
      		{
						# retrieve boundary marker for header separation
						$BOUNDARY = $NULL
						if ($REQUEST.ContentType -match "boundary=(.*);")
						{	$BOUNDARY = "--" + $MATCHES[1] }
						else
						{ # marker might be at the end of the line
							if ($REQUEST.ContentType -match "boundary=(.*)$")
							{ $BOUNDARY = "--" + $MATCHES[1] }
						}

if ($BOUNDARY)
	      		{ # only if header separator was found

# read complete header (inkl. file data) into string
      				$READER = New-Object System.IO.StreamReader($REQUEST.InputStream, $REQUEST.ContentEncoding)
							$DATA = $READER.ReadToEnd()
							$READER.Close()
							$REQUEST.InputStream.Close()

$PARAMETERS = ""
							$SOURCENAME = ""

# separate headers by boundary string
							$DATA -replace "$BOUNDARY--\r\n", "$BOUNDARY`r`n--" -split "$BOUNDARY\r\n" | % {
								# omit leading empty header and end marker header
								if (($_ -ne "") -and ($_ -ne "--"))
								{
									# only if well defined header (separation between meta data and data)
									if ($_.IndexOf("`r`n`r`n") -gt 0)
									{
										# header data before two CRs is meta data
										# first look for the file in header "filedata"
										if ($_.Substring(0, $_.IndexOf("`r`n`r`n")) -match "Content-Disposition: form-data; name=(.*);")
										{
											$HEADERNAME = $MATCHES[1] -replace '\"'
											# headername "filedata"?
											if ($HEADERNAME -eq "filedata")
											{ # yes, look for source filename
												if ($_.Substring(0, $_.IndexOf("`r`n`r`n")) -match "filename=(.*)")
												{ # source filename found
													$SOURCENAME = $MATCHES[1] -replace "`r`n$" -replace "`r$" -replace '\"'
													# store content of file in variable
													$FILEDATA = $_.Substring($_.IndexOf("`r`n`r`n") + 4) -replace "`r`n$"
											  }
											}
										}
										else
										{ # look for other headers (we need "parameter")
											if ($_.Substring(0, $_.IndexOf("`r`n`r`n")) -match "Content-Disposition: form-data; name=(.*)")
											{ # header found
												$HEADERNAME = $MATCHES[1] -replace '\"'
												# headername "parameter"?
												if ($HEADERNAME -eq "parameter")
												{ # yes, look for paramaters
													$PARAMETERS = $_.Substring($_.IndexOf("`r`n`r`n") + 4) -replace "`r`n$" -replace "`r$"
												}
											}
										}
									}
								}
							}

if ($SOURCENAME -ne "")
							{ # execute only if a source file exists

$EXECUTE = "function Powershell-WebServer-Func {`n" + $FILEDATA + "`n}`nPowershell-WebServer-Func " + $PARAMETERS
		    				try {
		    					# ... execute script
		    					$RESULT = Invoke-Expression -EA SilentlyContinue $EXECUTE 2> $NULL | Out-String
		    				}
		    				catch	{}
		    				if ($Error.Count -gt 0)
		    				{ # retrieve error message on error
		    					$RESULT += "`nError while executing script $SOURCENAME`n`n"
		    					$RESULT += $Error[0]
		    					$Error.Clear()
		    				}
							}
							else
							{
								$RESULT = "No file data received"
							}
      			}
					}
      	}
      	else
      	{
      		$RESULT = "No client data received"
      	}
      	break
      }

{ $_ -like "* /download" } # GET or POST method are allowed for download page
      {	# download file

# is POST data in the request?
      	if ($REQUEST.HasEntityBody)
      	{ # POST request
					# read complete header into string
   				$READER = New-Object System.IO.StreamReader($REQUEST.InputStream, $REQUEST.ContentEncoding)
					$DATA = $READER.ReadToEnd()
					$READER.Close()
					$REQUEST.InputStream.Close()

# get headers into hash table
					$HEADER = @{}
  				$DATA.Split('&') | % { $HEADER.Add([URI]::UnescapeDataString(($_.Split('=')[0] -replace "\+"," ")), [URI]::UnescapeDataString(($_.Split('=')[1] -replace "\+"," "))) }

# read header 'filepath'
  				$FORMFIELD = $HEADER.Item('filepath')
	    		# remove leading and trailing double quotes since Test-Path does not like them
	    		$FORMFIELD = $FORMFIELD -replace "^`"","" -replace "`"$",""
      	}
      	else
      	{ # GET request

# retrieve GET query string
		  		$FORMFIELD = ''
	  	  	$FORMFIELD = [URI]::UnescapeDataString(($REQUEST.Url.Query -replace "\+"," "))
	    		# remove fixed form fields out of query string
	    		$FORMFIELD = $FORMFIELD -replace "\?filepath=","" -replace "\?button=download","" -replace "&filepath=","" -replace "&button=download",""
	    		# remove leading and trailing double quotes since Test-Path does not like them
	    		$FORMFIELD = $FORMFIELD -replace "^`"","" -replace "`"$",""
      	}

# when path is given...
    		if (![STRING]::IsNullOrEmpty($FORMFIELD))
	   		{ # check if file exists
    			if (Test-Path $FORMFIELD -PathType Leaf)
    			{
			    	try {
			    		# ... download file
							$BUFFER = [System.IO.File]::ReadAllBytes($FORMFIELD)
							$RESPONSE.ContentLength64 = $BUFFER.Length
							$RESPONSE.SendChunked = $FALSE
							$RESPONSE.ContentType = "application/octet-stream"
							$FILENAME = Split-Path -Leaf $FORMFIELD
							$RESPONSE.AddHeader("Content-disposition", "attachment; filename=$FILENAME")
							$RESPONSE.OutputStream.Write($BUFFER, 0, $BUFFER.Length)
							# mark response as already given
	    				$RESPONSEWRITTEN = $TRUE
			    	}
			    	catch	{}
			    	if ($Error.Count -gt 0)
			    	{ # retrieve error message on error
			    		$RESULT += "`nError while downloading '$FORMFIELD'`n`n"
			    		$RESULT += $Error[0]
			    		$Error.Clear()
			    	}
		    	}
		    	else
		    	{
		    		# ... file not found
		    		$RESULT = "File $FORMFIELD not found"
		    	}
	    	}
	    	# preset form value with file path for the caller's convenience
   			$HTMLRESPONSE = $HTMLRESPONSE -replace '!FORMFIELD', $FORMFIELD
        break
      }

"GET /upload"
      { # present upload form, nothing to do here
      	break
      }

"POST /upload"
      { # upload file

if ($BOUNDARY)
	      		{ # only if header separator was found

# variables for filenames
							$FILENAME = ""
							$SOURCENAME = ""

# separate headers by boundary string
							$DATA -replace "$BOUNDARY--\r\n", "$BOUNDARY`r`n--" -split "$BOUNDARY\r\n" | % {
								# omit leading empty header and end marker header
								if (($_ -ne "") -and ($_ -ne "--"))
								{
									# only if well defined header (seperation between meta data and data)
									if ($_.IndexOf("`r`n`r`n") -gt 0)
									{
										# header data before two CRs is meta data
										# first look for the file in header "filedata"
										if ($_.Substring(0, $_.IndexOf("`r`n`r`n")) -match "Content-Disposition: form-data; name=(.*);")
										{
											$HEADERNAME = $MATCHES[1] -replace '\"'
											# headername "filedata"?
											if ($HEADERNAME -eq "filedata")
											{ # yes, look for source filename
												if ($_.Substring(0, $_.IndexOf("`r`n`r`n")) -match "filename=(.*)")
												{ # source filename found
													$SOURCENAME = $MATCHES[1] -replace "`r`n$" -replace "`r$" -replace '\"'
													# store content of file in variable
													$FILEDATA = $_.Substring($_.IndexOf("`r`n`r`n") + 4) -replace "`r`n$"
											  }
											}
										}
										else
										{ # look for other headers (we need "filepath" to know where to store the file)
											if ($_.Substring(0, $_.IndexOf("`r`n`r`n")) -match "Content-Disposition: form-data; name=(.*)")
											{ # header found
												$HEADERNAME = $MATCHES[1] -replace '\"'
												# headername "filepath"?
												if ($HEADERNAME -eq "filepath")
												{ # yes, look for target filename
													$FILENAME = $_.Substring($_.IndexOf("`r`n`r`n") + 4) -replace "`r`n$" -replace "`r$" -replace '\"'
												}
											}
										}
									}
								}
							}

if ($FILENAME -ne "")
							{ # upload only if a targetname is given
								if ($SOURCENAME -ne "")
								{ # only upload if source file exists

# check or construct a valid filename to store
									$TARGETNAME = ""
									# if filename is a container name, add source filename to it
									if (Test-Path $FILENAME -PathType Container)
									{
										$TARGETNAME = Join-Path $FILENAME -ChildPath $(Split-Path $SOURCENAME -Leaf)
									} else {
										# try name in the header
										$TARGETNAME = $FILENAME
									}

try {
			    					# ... save file with the same encoding as received
										[IO.File]::WriteAllText($TARGETNAME, $FILEDATA, $REQUEST.ContentEncoding)
			    				}
			    				catch	{}
			    				if ($Error.Count -gt 0)
			    				{ # retrieve error message on error
			    					$RESULT += "`nError saving '$TARGETNAME'`n`n"
			    					$RESULT += $Error[0]
			    					$Error.Clear()
			    				}
			    				else
			    				{ # success
      							$RESULT = "File $SOURCENAME successfully uploaded as $TARGETNAME"
      						}
								}
								else
								{
									$RESULT = "No file data received"
								}
							}
							else
							{
								$RESULT = "Missing target file name"
							}
      			}
					}
      	}
      	else
      	{
      		$RESULT = "No client data received"
      	}
      	break
      }

"GET /log"
      { # return the webserver log (stored in log variable)
      	$RESULT = $WEBLOG
      	break
      }

"GET /time"
      { # return current time
      	$RESULT = Get-Date -Format s
      	break
      }

"GET /starttime"
      { # return start time of the powershell webserver (already contained in $HTMLRESPONSE, nothing to do here)
      	break
      }

"GET /beep"
      { # Beep
      	[CONSOLE]::beep(800, 300) # or "`a" or [char]7
      	break
      }

"GET /quit"
      { # stop powershell webserver, nothing to do here
      	break
      }

"GET /exit"
      { # stop powershell webserver, nothing to do here
      	break
      }

default
 			{	# unknown command, return error
      	$RESPONSE.StatusCode = 404
      	$HTMLRESPONSE = '<html><body>Page not found</body></html>'
    	}

}

# only send response if not already done
    if (!$RESPONSEWRITTEN)
    {
    	# insert header line string into HTML template
   		$HTMLRESPONSE = $HTMLRESPONSE -replace '!HEADERLINE', $HEADERLINE

# insert result string into HTML template
   		$HTMLRESPONSE = $HTMLRESPONSE -replace '!RESULT', $RESULT

# return HTML answer to caller
    	$BUFFER = [Text.Encoding]::UTF8.GetBytes($HTMLRESPONSE)
    	$RESPONSE.ContentLength64 = $BUFFER.Length
    	$RESPONSE.OutputStream.Write($BUFFER, 0, $BUFFER.Length)
		}

# and finish answer to client
    $RESPONSE.Close()

# received command to stop webserver?
    if ($RECEIVED -eq 'GET /exit' -or $RECEIVED -eq 'GET /quit')
    { # then break out of while loop
    	"$(Get-Date -Format s) Stopping powershell webserver..."
    	break;
    }
  }
}
finally
{
  # Stop powershell webserver
  $LISTENER.Stop()
  $LISTENER.Close()
  "$(Get-Date -Format s) Powershell webserver stopped."
}