Convert PNG to Base64 in ASP

MeTV

I'm trying to write an ASP script to convert PNG files submitted through a form to Base64 strings without writing the file to the server first.

The code for the form is straightforward, as follows:

<form enctype="multipart/form-data" method="post">
	<input type="file" name="file" />
	<button type="submit">Convert</button>
</form>

And the code to process it and convert it to Base64 is as follows:

dim objXml,objStream,binFile
binFile=request.binaryread(request.totalbytes)
set objStream=server.createobject("ADODB.Stream")
objStream.type=1
objStream.open
objStream.write binFile
set objXML=server.createobject("MSXml2.DOMDocument")
set objXml=objXml.createelement("Base64Data")
objXml.datatype="bin.base64"
objXml.nodetypedvalue=objStream.read
response.write replace objXml.text
objStream.close:set objStream=nothing:set objXml=nothing

All works well, except the Base64 string includes the form "header" - Example:

------WebKitFormBoundarydXk7Jv8nzVuN2zps
Content-Disposition: form-data; name="file"; filename="file.png"
Content-Type: image/png

[I][File data here][/I]

Any suggestions/pointers for stripping it out at any stage of the process before the encoding takes place? Ideally, I'd also like to read "filename" and "Content-Type" into variables to help me verify that the file is actually a PNG.

Graham

Can you add a content type? I think it's something like:

response.ContentType="image/PNG"

Ignore that, just spotted the content-type is already detected.

MeTV

To clarify: I need to extract just the file data from the submitted data - e.g., just [File data here] from the third code box above.

stevenmu

I'm just going from a vague memory here, but I think the Response object can add headers in and I'm guessing that is possibly what is happening here. To test this quickly you could try writing out to a file instead of returning it via Response, just to check that it looks ok there.

From what I remember there are various properties on the Response object that you can set to control what headers are sent, so you should be able to use those to disable the headers entirely.

MeTV

Saved the stream to a text file and the header was included.

Graham

Are you outputting the object itself rather than just a string containing the converted image?