Upload multiple files from Powershell script

Question

I have a webapplication that can process POSTing of a html form like this:

Answer 1

I have found a solution to my problem after studying how multipart/form-data is built. A lot of help came in the form of http://www.paraesthesia.com/archive/2009/12/16/posting-multipartform-data-using-.net-webrequest.aspx.

The solution then is to build the body of the request up manually according to that convention. I have left of niceties like correct Content-Lengths etc.

Here is an excerpt of what I am using now:

    $path = "/Some/path/to/data/"

    $boundary_id = Get-Date -Format yyyyMMddhhmmssfffffff
    $boundary = "------------------------------" + $boundary_id

    $url = "http://..."
    [System.Net.HttpWebRequest] $req = [System.Net.WebRequest]::create($url)
    $req.Method = "POST"
    $req.ContentType = "multipart/form-data; boundary=$boundary"
    $ContentLength = 0
    $req.TimeOut = 50000

    $reqst = $req.getRequestStream()

    <#
    Any time you write a file to the request stream (for upload), you'll write:
        Two dashes.
        Your boundary.
        One CRLF (\r\n).
        A content-disposition header that tells the name of the form field corresponding to the file and the name of the file. That looks like:
        Content-Disposition: form-data; name="yourformfieldname"; filename="somefile.jpg" 
        One CRLF.
        A content-type header that says what the MIME type of the file is. That looks like:
        Content-Type: image/jpg
        Two CRLFs.
        The entire contents of the file, byte for byte. It's OK to include binary content here. Don't base-64 encode it or anything, just stream it on in.
        One CRLF.
    #>

    <# Upload #1: XFA #> 
    $xfabuffer = [System.IO.File]::ReadAllBytes("$path\P7-T.xml")

    <# part-header #>
    $header = "--$boundary`r`nContent-Disposition: form-data; name=`"xfa`"; filename=`"xfa`"`r`nContent-Type: text/xml`r`n`r`n"
    $buffer = [Text.Encoding]::ascii.getbytes($header)        
    $reqst.write($buffer, 0, $buffer.length)
    $ContentLength = $ContentLength + $buffer.length

    <# part-data #>
    $reqst.write($xfabuffer, 0, $xfabuffer.length)
    $ContentLength = $ContentLength + $xfabuffer.length

    <# part-separator "One CRLF" #>
    $terminal = "`r`n"
    $buffer = [Text.Encoding]::ascii.getbytes($terminal)        
    $reqst.write($buffer, 0, $buffer.length)
    $ContentLength = $ContentLength + $buffer.length

    <# Upload #1: PDF template #>
    $pdfbuffer = [System.IO.File]::ReadAllBytes("$path\P7-T.pdf")

    <# part-header #>
    $header = "--$boundary`r`nContent-Disposition: form-data; name=`"pdf`"; filename=`"pdf`"`r`nContent-Type: application/pdf`r`n`r`n"
    $buffer = [Text.Encoding]::ascii.getbytes($header)        
    $reqst.write($buffer, 0, $buffer.length)
    $ContentLength = $ContentLength + $buffer.length

    <# part-data #>
    $reqst.write($pdfbuffer, 0, $pdfbuffer.length)
    $ContentLength = $ContentLength + $pdfbuffer.length

    <# part-separator "One CRLF" #>
    $terminal = "`r`n"
    $buffer = [Text.Encoding]::ascii.getbytes($terminal)        
    $reqst.write($buffer, 0, $buffer.length)
    $ContentLength = $ContentLength + $buffer.length

    <#
    At the end of your request, after writing all of your fields and files to the request, you'll write:

    Two dashes.
    Your boundary.
    Two more dashes.
    #>
    $terminal = "--$boundary--"
    $buffer = [Text.Encoding]::ascii.getbytes($terminal)        
    $reqst.write($buffer, 0, $buffer.length)
    $ContentLength = $ContentLength + $buffer.length

    $reqst.flush()
    $reqst.close()

    # Dump request to console
    #$req

    [net.httpWebResponse] $res = $req.getResponse()

    # Dump result to console
    #$res

    # Dump result-body to filesystem
<#    
    $resst = $res.getResponseStream()
    $sr = New-Object IO.StreamReader($resst)
    $result = $sr.ReadToEnd()
    $res.close()
#>

    $null = New-Item -ItemType Directory -Force -Path "$path\result"
    $target = "$path\result\P7-T.pdf"

    # Create a stream to write to the file system.
    $targetfile = [System.IO.File]::Create($target)

    # Create the buffer for copying data.
    $buffer = New-Object Byte[] 1024

    # Get a reference to the response stream (System.IO.Stream).
    $resst = $res.GetResponseStream()

    # In an iteration...
    Do {
        # ...attemt to read one kilobyte of data from the web response stream.
        $read = $resst.Read($buffer, 0, $buffer.Length)

        # Write the just-read bytes to the target file.
        $targetfile.Write($buffer, 0, $read)

        # Iterate while there's still data on the web response stream.
    } While ($read -gt 0)

    # Close the stream.
    $resst.Close()
    $resst.Dispose()

    # Flush and close the writer.
    $targetfile.Flush()
    $targetfile.Close()
    $targetfile.Dispose()