XDPing PowerShell Function

Function XDPing {
  # This function performs an XDPing to make sure the Delivery Controller or Cloud Connector is in a healthy state.
  # It tests whether the Broker service is reachable, listening and processing requests on its configured port.
  # We do this by issuing a blank HTTP POST requests to the Broker's Registrar service. Including "Expect: 100-continue"
  # in the body will ensure we receive a respose of "HTTP/1.1 100 Continue", which is what we use to verify that it's in
  # a healthy state.
  # You will notice that you can also pass proxy parameters to the function. This is for test and development ONLY. I
  # added this as I was using Fiddler to test the functionality and make sure the raw data sent was correctly formatted.
  # I decided to leave these parameters in the function so that others can learn and understand how this works.
  # To work out the best way to write this function I decompiled the VDAAssistant.Backend.dll from the Citrix Health
  # Assistant tool using JetBrains decompiler.
  # Written by Jeremy Saunders
  param(
    [Parameter(Mandatory=$True)][String]$ComputerName, 
    [Parameter(Mandatory=$True)][Int32]$Port,
    [String]$ProxyServer="", 
    [Int32]$ProxyPort,
    [Switch]$ConsoleOutput
  )
  $service = "http://${ComputerName}:${Port}/Citrix/CdsController/IRegistrar"
  $s = "POST $service HTTP/1.1`r`nContent-Type: application/soap+xml; charset=utf-8`r`nHost: ${ComputerName}:${Port}`r`nContent-Length: 1`r`nExpect: 100-continue`r`nConnection: Close`r`n`r`n"
  $log = New-Object System.Text.StringBuilder
  $log.AppendLine("Attempting an XDPing against $ComputerName on TCP port number $port") | Out-Null
  $listening = $false
  If ([string]::IsNullOrEmpty($ProxyServer)) {
    $ConnectToHost = $ComputerName
    [int]$ConnectOnPort = $Port
  } Else {
    $ConnectToHost = $ProxyServer
    [int]$ConnectOnPort = $ProxyPort
    $log.AppendLine("- Connecting via a proxy: ${ProxyServer}:${ProxyPort}") | Out-Null
  }
  try {
    $socket = New-Object System.Net.Sockets.Socket ([System.Net.Sockets.AddressFamily]::InterNetwork, [System.Net.Sockets.SocketType]::Stream, [System.Net.Sockets.ProtocolType]::Tcp)
    try {
      $socket.Connect($ConnectToHost,$ConnectOnPort)
      if ($socket.Connected) {
        $log.AppendLine("- Socket connected") | Out-Null
        $bytes = [System.Text.Encoding]::ASCII.GetBytes($s)
        $socket.Send($bytes) | Out-Null
        $log.AppendLine("- Sent the data") | Out-Null
        $numArray = New-Object byte[] 21
        $socket.ReceiveTimeout = 5000
        $socket.Receive($numArray) | Out-Null
        $log.AppendLine("- Received the following 21 byte array: " + [BitConverter]::ToString($numArray)) | Out-Null
        $strASCII = [System.Text.Encoding]::ASCII.GetString($numArray)
        $strUTF8 = [System.Text.Encoding]::UTF8.GetString($numArray)
        $log.AppendLine("- Converting to ASCII: `"$strASCII`"") | Out-Null
        $log.AppendLine("- Converting to UTF8: `"$strUTF8`"") | Out-Null
        $socket.Send([byte[]](32)) | Out-Null
        $log.AppendLine("- Sent a single byte with the value 32 (which represents the ASCII space character) to the connected socket.") | Out-Null
        $log.AppendLine("- This is done to gracefully signal the end of the communication.") | Out-Null
        $log.AppendLine("- This ensures it does not block/consume unnecessary requests needed by VDAs.") | Out-Null
        if ($strASCII.Trim().StartsWith("HTTP/1.1 100 Continue", [System.StringComparison]::CurrentCultureIgnoreCase)) {
          $listening = $true
          $log.AppendLine("- The service is listening and healthy") | Out-Null
        } else {
          $log.AppendLine("- The service is not listening") | Out-Null
        }
        try {
          $socket.Close()
          $log.AppendLine("- Socket closed") | Out-Null
        } catch {
          $log.AppendLine("- Failed to close socket") | Out-Null
          $log.AppendLine("- ERROR: $_") | Out-Null
        }
        $socket.Dispose()
      } else {
        $log.AppendLine("- Socket failed to connect") | Out-Null
      }
    } catch {
      $log.AppendLine("- Failed to connect to service") | Out-Null
      $log.AppendLine("- ERROR: $_") | Out-Null
    }
  } catch {
    $log.AppendLine("- Failed to create socket") | Out-Null
    $log.AppendLine("- ERROR: $_") | Out-Null
  }
  If ($ConsoleOutput) {
    Write-Host $log.ToString().TrimEnd()
  }
  return $listening
}

$ComputerName = "cxdt01.jhouseconsulting.com"
$Port = 80

XDPing -ComputerName $ComputerName -Port $Port