Create code for upload validation

[cfedermann]

Create code that validates the uploaded file in order to prevent abuse. The exact "method" for validation is to-be-defined, feel free to play around.

Some basic ideas are:

• implement a basic filename/extension checker (.zip or .xml);
• check if file is actually binary (for .zip) or contains text (.xml);
• check that file size is within in "sane" limits;
• check file integrity by extracting the .zip archive;
• validate .xml files before running the Perl code.

Django's documentation on "Form and field validation" is available here:

• https://docs.djangoproject.com/en/1.4/ref/forms/validation/

It should not be necessary to create a customised FileUpload field, though.

XML well-formedness can be checked using the xmlwf command line tool; XML validity can be checked using xmllint.

[itsjeyd]

Complete; addressed by pull request #6.

Before accepting any given file, TrendMiner checks:

• File extension
• File size (both client-side and server-side)
• MIME type
• .zip integrity
• .zip contents (i.e., does the archive include any non-XML files?)
• XML well-formedness
• XML schema conformity

[cfedermann]

Thanks! This closes the issue.