Script to show each step of a redirection chain

show-redirects.ps1

param(
  [string]$startURL,
  [switch]$showall
)

$ErrorActionPreference = 'Stop'
$Error.Clear()
$lastError = $null

function getUrl {
  param([uri]$url)
  $wr = [System.Net.WebRequest]::Create($url)
  $wr.Method= 'GET'
  $wr.Timeout = 25000
  $wr.AllowAutoRedirect = $false
  $wr.UserAgent = 'Redirect crawler'
  try {
    $resp = [System.Net.HttpWebResponse]$wr.GetResponse()
    $resp
  }
  catch [System.Net.WebException] {
    $script:lastError = $error[0].Exception.InnerException
    $error[0].Exception.InnerException.Response
    $Error.Clear()
  }
}

$locationlist = @()
while ($startURL -ne '') {
  $response = getURL $startURL
  if ($response -eq $null) {
    $result = new-object -type psobject -prop ([ordered]@{
      requestURL=$startURL
      statusCode=$lastError.Status
      status= $lastError.Message
      location=$startURL
    })
    break
  }
  if ($locationlist.Contains($response.Headers['Location'])) {
    $result = new-object -type psobject -prop ([ordered]@{
      requestURL=$startURL
      statusCode='RedirLoop'
      status= 'Redirection loop!'
      location=$response.Headers['Location']
    })
    break
  }
  if ($Error.Count -ne 0) {
    break
  }
  switch ($response.StatusCode.value__) {
    301 {
        $result = new-object -type psobject -prop ([ordered]@{
          requestURL=$startURL
          statusCode=$response.StatusCode.value__
          status= $response.StatusDescription
          location=$response.Headers['Location']
        })
        if ($response.Headers['Location'].StartsWith('/')) {
            $baseURL = [uri]$response.ResponseUri
            $startURL = $baseURL.Scheme + '://'+ $baseURL.Host + $response.Headers['Location']
        } elseif ($response.Headers['Location'].StartsWith('http')) {
          $startURL = $response.Headers['Location']
        } else {
          $baseURL = [uri]$response.ResponseUri
          $startURL = $baseURL.Scheme + '://'+ $baseURL.Host + $baseURL.AbsolutePath + $response.Headers['Location']
        }
        break
      }
    302 {
        $result = new-object -type psobject -prop ([ordered]@{
          requestURL=$startURL
          statusCode=$response.StatusCode.value__
          status= $response.StatusDescription
          location=$response.Headers['Location']
        })
        if ($response.Headers['Location'].StartsWith('/')) {
          $baseURL = [uri]$response.ResponseUri
          $startURL = $baseURL.Scheme + '://'+ $baseURL.Host + $response.Headers['Location']
        } elseif ($response.Headers['Location'].StartsWith('http')) {
          $startURL = $response.Headers['Location']
        } else {
          $baseURL = [uri]$response.ResponseUri
          $startURL = $baseURL.Scheme + '://'+ $baseURL.Host + $baseURL.AbsolutePath + $response.Headers['Location']
        }
        break
      }
    304 {
        $result = new-object -type psobject -prop ([ordered]@{
          requestURL=$startURL
          statusCode=$response.StatusCode.value__
          status= $response.StatusDescription
          location=$response.Headers['Location']
        })
        if ($response.Headers['Location'].StartsWith('/')) {
          $baseURL = [uri]$response.ResponseUri
          $startURL = $baseURL.Scheme + '://'+ $baseURL.Host + $response.Headers['Location']
        } elseif ($response.Headers['Location'].StartsWith('http')) {
          $startURL = $response.Headers['Location']
        } else {
          $baseURL = [uri]$response.ResponseUri
          $startURL = $baseURL.Scheme + '://'+ $baseURL.Host + $baseURL.AbsolutePath + $response.Headers['Location']
        }
        break
      }
    404 {
        $result = new-object -type psobject -prop ([ordered]@{
          requestURL=$startURL
          statusCode=$response.StatusCode.value__
          status= $response.StatusDescription
          location=$startURL
        })
        $startURL = ''
        break
        }
    200 {
        $result = new-object -type psobject -prop ([ordered]@{
          requestURL=$response.ResponseUri
          statusCode=$response.StatusCode.value__
          status= $response.StatusDescription
          location=$response.ResponseUri
        })
        $startURL = ''
        break
      }
    default {
        $result = new-object -type psobject -prop ([ordered]@{
          requestURL=$startURL
          statusCode=$response.StatusCode.value__
          status= $response.StatusDescription
          location=$response.ResponseUri
        })
        $startURL = ''
        break
      }
  }
  $locationlist += $response.Headers['Location']
  if ($showall) {
    write-output $result
    $result = $null
  }
}
if ($result) { write-output $result }
$locationlist = @()