Category: PowerShell

In order to check header values from a HTTP get sometimes you need to follow a Re-direct to be able to inspect those headers.

This post will show how you how to follow web site redirects:

First we start with creating a Web request object from System.Net.WebRequest

$url = "some url that has redirects"
$request = [System.Net.WebRequest]::Create($url)

With the object for webrequest in the variable request we can set the properties of that object and set the property AllowAutoRedirect to false.

$url = "https://www.google.com"
$request = [System.Net.WebRequest]::Create($url)

Now ask the $request object for a response.

$response=$request.GetResponse()

if($response.Statuscode.toString() -eq "Found")
{}

For each type of response (HttpWebResponse), we can find the methods and properties for that class and in turn take action on them. The first one to take action is the status code. There are a number of response types that you can check for in our case we want to check for any of the status’ that would cause a redirect. Which for the sake of demonstration we’ll start with “Redirect — 302”.

elseif($response.statuscode.tostring() -eq 'Redirect')
{
  $stream = $response.getresponseStream()
  $streamReader = [System.IO.Streamreader]::new($stream)
  $html = $streamReader.ReadtoEnd()
}

When a redirect is detected, the html that is with the redirect must be read to know where the redirect is going to. This is done through creation of a Stream reader to read the stream on the response object. To find the redirect path a small funtion is introduced to read the html object and find the path to where we need to follow the next redirect:

function Get-RedirectPath
{
param($html)
$h = convertfrom-html $html
if((($h.all.tags('Title)) | select-Object -expandProperty text).toString() -eq "Object moved")
{
   ($H.all.tags('a')) | select-object -first 1 -Expandproperty pathname
}
elseif((($h.all.tags('Title)) | select-Object -expandProperty text).toString() -eq "Document moved")
{
  ($H.all.tags('a')) | select-object -first 1 -Expandproperty pathname
}
else
{$null}
}

This function takes the html raw text and converts it to html. When converted to Html we can then look through the tags find the title and look for Document or object moved and get the value in the ‘a’ tag for where the redirect is to. In addition to following the redirect the other requirement was to get the headers in each redirect. Get-Headers is a function created for just this purpose.

Function Get-headers
{
   param([System.Net.HttpWebResponse]$HttpWebResponse)
   $headerHash = @{}
  foreach($header in $HttpWebResponse.headers)
  {
   $headerhash += @{$header = $response.GeteEsponseHeader($header)}
  }
 $headerHash
}

Get-Headers expects and object type of System.Net.HttpWebResponse. Since we have that object type we can call one of its methods to get the response headers. And add each header to a hash table.

If there are no headers then an empty Hashtable will be returned.

Lastly for pass back to the caller the other requirement was to include the $html, $headerhash, $redirect status code, and the date time. In a custom object so decisions could be made on whether or not to follow into the next redirect. Redirect status code is only added when we have a Redirect any other status code that isn’t a redirect will not contain this property.

The full completed scripts are found in this GIST:

In order to test some websites I had need to have a function that produced random words.

I found this random word Json list. https://raw.githubusercontent.com/RazorSh4rk/random-word-api/master/words.json

And decided to wrap a small function around it:

function Get-RandomWord
{
if(-not $words)
{

$Script:words = (invoke-webrequest -Uri https://raw.githubusercontent.com/RazorSh4rk/random-word-api/master/words.json).content | convertfrom-json

}

$words["$(get-random -Maximum ($words.count))"]
}

if you wish to change to your own list of random words just change the json location to a local directory with a json file or a different web url that contains the json you want to Randomize.

Until then

I hope this helps someone

thom

There was a question presented on StackOverflow about how do you pull an image from the Clipboard.  This article is about how this was done with two separate functions.

The first function Export-ClipItem is a function that detects what type of item is in the Clipboard.  To perform this function the built in cmdlets with powershell 5.1 work nicely.  This script however, is written assuming that an older version of Powershell maybe required.

The first thing that needs to be done is to get a windows form object:

Add-Type -AssemblyName System.Windows.Forms

$clipboard = [System.Windows.Forms.Clipboard]::GetDataObject()

The the Windows Forms object added the clipboard is now accessible.  If the $clipboard object is inspected:

$clipboard | get-member

TypeName: System.Windows.Forms.DataObject

Name MemberType Definition 
---- ---------- ---------- 
ContainsAudio Method bool ContainsAudio() 
ContainsFileDropList Method bool ContainsFileDropList() 
ContainsImage Method bool ContainsImage() 
ContainsText Method bool ContainsText(), bool ContainsText(System.Windows.Forms.TextDataFormat format) 

.....

GetAudioStream Method System.IO.Stream GetAudioStream() 
GetCanonicalFormatEtc Method int IDataObject.GetCanonicalFormatEtc([ref] GetFileDropList Method System.Collections.Specialized.StringCollection GetFileDropList() 

.....

GetImage Method System.Drawing.Image GetImage() 
GetText Method string GetText(), string GetText(System.Windows.Forms.TextDataFormat format) 

Based upon inspection there are several items that can be tested for with (Contains) and then items can be retrieved from the clipboard with (Get) methods.

Starting with Text it can be tested with ContainsText(). Retrieval of the Text can then be done with GetText()

 

if($clipboard.ContainsText())
{

$clipboard.GetText() | Out-File -FilePath "c:\temp\temp.txt"

}

ContainsImage() is a little bit trickier. Using getImage() the type of object it contains can be seen with gettype()

$clipboard.getimage().gettype()

IsPublic IsSerial Name BaseType 
-------- -------- ---- -------- 
True True Bitmap System.Drawing.Image

Since the Image retrieved from the clipboard is aready a System.Drawing.Image type.  That library has a Save() function.  it requires the path to save the image to and a type to save the image as.

$clipboard.getimage().save("c:\temp\clip.png",[System.Drawing.Imaging.ImageFormat]::Png)

Inspection of the Class for System.Drawing.Imaging.ImageFormat demonstrates there are a number of image formats that can be saved:

[System.Drawing.Imaging.ImageFormat].getproperties().Name
Png
Guid
MemoryBmp
Bmp
Emf
Wmf
Gif
Jpeg
Tiff
Exif
Icon

There are two other types of data that can be retrieved from the clipboard.

1. ContainsFileDropList()

A file drop list is a collection of strings containing path information for files. The return from GetFileDropList is a StringCollection.  For this blog post it was chosen to just save the contents of the return as a txt file.

if($clipboard.ContainsFileDropList())

{

$clipboard.GetFileDropList()| Out-File -FilePath "c:\temp\temp.txt"

}

2. AudioFile

The last type that can be retrieved from the clipboard is an Audio file.  Performing the Export of the Audio will be presented in the next Blog post on this topic.

if($clipboard.ContainsAudio())
{
$clipboard.GetAudioStream()

#perform stream function to file ()
}

Now that we have the different types of output Text, Images, FileDropList, and at a later Date audio.  Now exploration of the File name function can be explored.  For this Script it was decided to write out a single file for each Clipboard operation.  This next explanation demonstrates how this was done.

function new-fileobject
{ param([string]$path, [string]$ext)

if(!(test-path $path -PathType Leaf -ErrorAction Ignore))
{
if([system.io.path]::GetExtension($path))
{
$filename = [system.io.path]::GetFileNameWithoutExtension([system.io.path]::GetFileName($path))
$path = [System.IO.Path]::GetDirectoryName($Path)
if(!(test-path $path -ErrorAction Ignore))
{new-item $path -Force}
}
else
{
$filename = [system.io.path]::getfilename($path)
$path = [system.io.path]::getdirectoryname($path)
if(!(test-path $path -ErrorAction Ignore))
{new-item $path -Force}
}
}
else
{
$filename = [system.io.path]::GetFileNameWithoutExtension([system.io.path]::GetFileName($path))
$path = [System.IO.Path]::GetDirectoryName($Path)
}
if([string]::IsNullOrEmpty($filename))
{
$filename = 'clip'
}
if(test-path "$path\$filename*")
{
[int]$lastFilenameNumber=((gi -path "$path\$filename*").BaseName | select-string '^\D+\d*$' | select -Last 1) -replace '^\D+',''
if($lastFilenameNumber)
{
$filename = "$filename$($lastFilenameNumber + 1)"
}
elseif(get-item "$path\$filename$($ext)")
{
$filename = "$filename$($lastFilenameNumber + 1)"
}
}
[pscustomobject]@{'filename' = $filename; 'path' = $path; 'ext' = $ext; 'fullpath' = "$path\$filename$($ext)"}
}

The object of this function was to take a file path ($Path) and an extension ($ext).

1. Determine if the file & path exists. If path nor file exists create one or both.
2. Determine if the file is already there. If it is present detect the current number of the file and add one.
3. Return the filename, path, extension and fullpath.

With that function in place the script is now complete:

param([string]$path)

function export-clipItem
{
param($path)
Add-Type -AssemblyName System.Windows.Forms
#get the file extension and path

$clipboard = [System.Windows.Forms.Clipboard]::GetDataObject()

if ($clipboard.ContainsImage())
{ $ext = '.png'
$fileobject = new-fileobject $path $ext
[System.Drawing.Bitmap]$clipboard.getimage().Save("$($fileobject.fullpath)", [System.Drawing.Imaging.ImageFormat]::Png)
#https://social.msdn.microsoft.com/Forums/vstudio/en-US/9c2a05de-c680-4515-898a-e92f28eddbf9/retrieve-image-from-clipboard-and-save-it-in-different-formats
}
elseif($clipboard.ContainsText())
{
$ext = '.txt'
$fileobject = new-fileobject $path $ext
$clipboard.GetText() | Out-File -FilePath "$($fileobject.fullpath)"
}
elseif($clipboard.ContainsAudio())
{
$ext = '.wav'
$fileobject = new-fileobject $path $ext
$clipboard.GetAudioStream() #| out-file -FilePath "$($fileobject.fullpath)"
#create stream and output to file goes here.
}
elseif($clipboard.ContainsFileDropList())
{
$ext = '.txt'
$fileobject = new-fileobject $path $ext
$clipboard.GetFileDropList()| Out-File -FilePath "$($fileobject.fullpath)"
}
Write-Output "$($fileobject.fullpath)"
}

function new-fileobject
{ param([string]$path, [string]$ext)

if(!(test-path $path -PathType Leaf -ErrorAction Ignore))
{
if([system.io.path]::GetExtension($path))
{
$filename = [system.io.path]::GetFileNameWithoutExtension([system.io.path]::GetFileName($path))
$path = [System.IO.Path]::GetDirectoryName($Path)
if(!(test-path $path -ErrorAction Ignore))
{new-item $path -Force}
}
else
{
$filename = [system.io.path]::getfilename($path)
$path = [system.io.path]::getdirectoryname($path)
if(!(test-path $path -ErrorAction Ignore))
{new-item $path -Force}
}
}
else
{
$filename = [system.io.path]::GetFileNameWithoutExtension([system.io.path]::GetFileName($path))
$path = [System.IO.Path]::GetDirectoryName($Path)
}
if([string]::IsNullOrEmpty($filename))
{
$filename = 'clip'
}
if(test-path "$path\$filename*")
{
[int]$lastFilenameNumber=((gi -path "$path\$filename*").BaseName | select-string '^\D+\d*$' | select -Last 1) -replace '^\D+',''
if($lastFilenameNumber)
{
$filename = "$filename$($lastFilenameNumber + 1)"
}
elseif(get-item "$path\$filename$($ext)")
{
$filename = "$filename$($lastFilenameNumber + 1)"
}
}
[pscustomobject]@{'filename' = $filename; 'path' = $path; 'ext' = $ext; 'fullpath' = "$path\$filename$($ext)"}
}
export-clipItem $path

I hope this helps Someone