Posting HTTP form without using 'Invoke-WebRequest'

Question

I have a working PowerShell 3.0 script that takes advantage of Invoke-WebRequest to post a form and save the respective raw HTML output. Unfortunately, the script doesn't work on workstations with only PowerShell 2.0.

I was hoping someone could please help convert the below script to work with PowerShell 2.0 (without having to install PS modules, packages, or upgrade PowerShell). It looks like I need to use .NET webclient, but I'm not experienced enough to do this yet. A working example (based on my script) would be extremely appreciated!

PS: I'm using sls -pattern to filter out content in the raw HTML output. If there's a more reliable way to identify certain items in the raw output, I wouldn't mind seeing an example.

$UserAgent = 'Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET CLR 1.1.4322; InfoPath.3; MS-RTC LM 8; .NET4.0E)'
$r=Invoke-WebRequest -Uri 'http://web.ourwebserver.com/test.aspx' -UseDefaultCredentials -SessionVariable WebSession
$form = $r.Forms[0]

$fields = Invoke-WebRequest -Uri 'http://web.ourwebserver.com/test.aspx' -WebSession $WebSession | select -ExpandProperty inputfields | select name, value

$viewstate = $fields | ?{$_.name -match "VIEWSTATE"} | select -ExpandProperty value
$eventvalidation = $fields | ?{$_.name -match "EVENTVALIDATION"} | select -ExpandProperty value

$form.Fields["__EVENTVALIDATION"] = $eventvalidation
$form.Fields["ctl00`$MainContent`$phone"] = "454-454-2345"
$form.Fields["ctl00`$MainContent`$Submit"] = "Submit"

$response = Invoke-WebRequest -Uri 'http://web.ourwebserver.com/test.aspx' -WebSession $WebSession -Method POST -Body $form.Fields -ContentType 'application/x-www-form-urlencoded'
$result = $response.rawcontent

EDIT: Below, is my first attempt at getting the script to work. Anyway, it's obviously not doing the same thing as my WORKING Invoke-WebRequest script above

$URL = "http://web.ourwebserver.com/test.aspx"
$wc = new-object net.WebClient
$wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded")
$wc.Headers.Add("User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET CLR 1.1.4322; InfoPath.3; MS-RTC LM 8; .NET4.0E)")
$wc.UseDefaultCredentials = $true

### EventValidation/ViewState Extraction Code ###
$probe = $wc.downloadData($url)
$s = [text.encoding]::ascii.getString($probe)
$start = $s.indexOf('id="__VIEWSTATE"', 0) + 24
$end = $s.indexOf('"', $start)
$viewstate = $s.substring($start, $end-$start)
$start = $s.indexOf('id="__EVENTVALIDATION"', 0) + 30
$end = $s.indexOf('"', $start)
$eventvalidation = $s.substring($start, $end-$start)
###

$NVC = New-Object System.Collections.Specialized.NameValueCollection
$NVC.Add("__EVENTVALIDATION", $eventvalidation)
$NVC.Add("ctl00`$MainContent`$phone", "454-454-2345")
$NVC.Add("ctl00`$MainContent`$Submit", "Submit")
$wc.QueryString = $NVC

$Result = $WC.UploadValues($URL,"POST", $NVC)

[System.Text.Encoding]::UTF8.GetString($Result)

$WC.Dispose();

Answer 1

Here is the code I use to post my Web requests, this is not the exact answer, but I suppose you can adapt it :

Add-Type -AssemblyName System.ServiceModel.Web, System.Runtime.Serialization, System.Web.Extensions

$utf8 = [System.Text.Encoding]::UTF8

function Request-Rest
{
  [CmdletBinding()]
  PARAM (
         [Parameter(Mandatory=$true)]
         [String] $URL,

         [Parameter(Mandatory=$false)]
         [System.Net.NetworkCredential] $credentials,

         [Parameter(Mandatory=$true)]
         [String] $JSON)

  # Remove NewLine from json
  $JSON = $JSON -replace "$([Environment]::NewLine) *",""  

  # Create a URL instance since the HttpWebRequest.Create Method will escape the URL by default.   
  # $URL = Fix-Url $Url
  $URI = New-Object System.Uri($URL,$true)   

  try
  {
    # Create a request object using the URI   
    $request = [System.Net.HttpWebRequest]::Create($URI)   
    # Build up a nice User Agent   
    $UserAgent = "Your user agent name"
    $request.UserAgent = $("{0} (PowerShell {1}; .NET CLR {2}; {3})" -f $UserAgent, $(if($Host.Version){$Host.Version}else{"1.0"}),  
                           [Environment]::Version,  
                           [Environment]::OSVersion.ToString().Replace("Microsoft Windows ", "Win"))

    $request.Credentials = $credentials
    $request.KeepAlive = $true
    $request.Pipelined = $true
    $request.AllowAutoRedirect = $false
    $request.Method = "POST"
    $request.ContentType = "application/json"
    $request.Accept = "application/json"

    $utf8Bytes = [System.Text.Encoding]::UTF8.GetBytes($JSON)
    $request.ContentLength = $utf8Bytes.Length
    $postStream = $request.GetRequestStream()
    $postStream.Write($utf8Bytes, 0, $utf8Bytes.Length)
    #Write-String -stream $postStream -string $JSON
    $postStream.Dispose()

    try
    {
      #[System.Net.HttpWebResponse] $response = [System.Net.HttpWebResponse] $request.GetResponse()
      $response = $request.GetResponse()
    }
    catch
    {
      $response = $Error[0].Exception.InnerException.Response; 
      Throw "Exception occurred in $($MyInvocation.MyCommand): `n$($_.Exception.Message)"
    }

    $reader = [IO.StreamReader] $response.GetResponseStream()  
    $output = $reader.ReadToEnd()  

    $reader.Close()  
    $response.Close()
    Write-Output $output  
  }
  catch
  {
    $output = @"
    {
      "error":1,
      "error_desc":"Request-Rest Internal : Serveur access problem $($_.Exception.Message)"
    }
"@    
    Write-Output $output
  }
}

Answer 2

It looks like I was very close to getting it working. For some reason, I also needed to include __VIEWSTATE (in addition to __EVENTVALIDATION) in the POST. I was able to determine this by verifying form data via Fiddler.

$URL = "http://web.ourwebserver.com/test.aspx"
$wc = new-object net.WebClient
$wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded")
$wc.Headers.Add("User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727)")
$wc.UseDefaultCredentials = $true

### EventValidation/ViewState Extraction Code ###
$probe = $wc.downloadData($url)
$s = [text.encoding]::ascii.getString($probe)
$start = $s.indexOf('id="__VIEWSTATE"', 0) + 24
$end = $s.indexOf('"', $start)
$viewstate = $s.substring($start, $end-$start)
$start = $s.indexOf('id="__EVENTVALIDATION"', 0) + 30
$end = $s.indexOf('"', $start)
$eventvalidation = $s.substring($start, $end-$start)
###

$NVC = New-Object System.Collections.Specialized.NameValueCollection
$NVC.Add("__VIEWSTATE", $viewstate);
$NVC.Add("__EVENTVALIDATION", $eventvalidation);
$NVC.Add("ctl00`$MainContent`$phone", "454-454-2345");
$NVC.Add("ctl00`$MainContent`$Submit", "Submit");
$wc.QueryString = $NVC

$Result = $WC.UploadValues($URL,"POST", $NVC)

[System.Text.Encoding]::UTF8.GetString($Result)

$WC.Dispose();