Fix #678 -- Data shredders for personally identifiable information (#817)

* Add data shredders for PII

* First working shredder

* Add more shredders

* Add new shredders and download confirmation

* tmp

* PayPal, Stripe, banktransfer

* Add icon to logs

* Untested payment log shredders

* Add waiting list shredder

* First tests

* Add tests for shredders

* Improve templats, link to shredder

* Test payment info shredders

* More tests

* Documentation

* Fix enabled flag in payment provider overview

* Fix minor issues

src/pretix/base/services/invoices.py

@@ -180,6 +180,8 @@ def generate_cancellation(invoice: Invoice, trigger_pdf=True):
 
 
 def regenerate_invoice(invoice: Invoice):
+    if invoice.shredded:
+        return invoice
     if invoice.is_cancellation:
         invoice = build_cancellation(invoice)
     else:
@@ -214,6 +216,10 @@ def generate_invoice(order: Order, trigger_pdf=True):
 @app.task(base=TransactionAwareTask)
 def invoice_pdf_task(invoice: int):
     i = Invoice.objects.get(pk=invoice)
+    if i.shredded:
+        return None
+    if i.file:
+        i.file.delete()
     with language(i.locale):
         fname, ftype, fcontent = i.event.invoice_renderer.generate(i)
         i.file.save(fname, ContentFile(fcontent))

src/pretix/base/services/shredder.py

@@ -0,0 +1,91 @@
+import json
+from datetime import timedelta
+from tempfile import NamedTemporaryFile
+from typing import List
+from zipfile import ZipFile
+
+from dateutil.parser import parse
+from django.conf import settings
+from django.utils.crypto import get_random_string
+from django.utils.timezone import now
+from django.utils.translation import ugettext_lazy as _
+
+from pretix.base.models import CachedFile, Event, cachedfile_name
+from pretix.base.services.async import ProfiledTask
+from pretix.base.shredder import ShredError
+from pretix.celery_app import app
+
+
+@app.task(base=ProfiledTask)
+def export(event: str, shredders: List[str]) -> None:
+    event = Event.objects.get(id=event)
+    known_shredders = event.get_data_shredders()
+
+    with NamedTemporaryFile() as rawfile:
+        with ZipFile(rawfile, 'w') as zipfile:
+            ccode = get_random_string(6)
+            zipfile.writestr(
+                'CONFIRM_CODE.txt',
+                ccode,
+            )
+            zipfile.writestr(
+                'index.json',
+                json.dumps({
+                    'instance': settings.SITE_URL,
+                    'organizer': event.organizer.slug,
+                    'event': event.slug,
+                    'time': now().isoformat(),
+                    'shredders': shredders,
+                    'confirm_code': ccode
+                }, indent=4)
+            )
+            for s in shredders:
+                shredder = known_shredders.get(s)
+                if not shredder:
+                    continue
+
+                it = shredder.generate_files()
+                if not it:
+                    continue
+                for fname, ftype, content in it:
+                    zipfile.writestr(fname, content)
+
+        rawfile.seek(0)
+
+        cf = CachedFile()
+        cf.date = now()
+        cf.filename = event.slug + '.zip'
+        cf.type = 'application/pdf'
+        cf.expires = now() + timedelta(hours=1)
+        cf.save()
+        cf.file.save(cachedfile_name(cf, cf.filename), rawfile)
+
+    return cf.pk
+
+
+@app.task(base=ProfiledTask, throws=(ShredError,))
+def shred(event: str, fileid: str, confirm_code: str) -> None:
+    event = Event.objects.get(id=event)
+    known_shredders = event.get_data_shredders()
+    try:
+        cf = CachedFile.objects.get(pk=fileid)
+    except CachedFile.DoesNotExist:
+        raise ShredError(_("The download file could no longer be found on the server, please try to start again."))
+    with ZipFile(cf.file.file, 'r') as zipfile:
+        indexdata = json.loads(zipfile.read('index.json').decode())
+    if indexdata['organizer'] != event.organizer.slug or indexdata['event'] != event.slug:
+        raise ShredError(_("This file is from a different event."))
+    if indexdata['confirm_code'] != confirm_code:
+        raise ShredError(_("The confirm code you entered was incorrect."))
+    if event.logentry_set.filter(datetime__gte=parse(indexdata['time'])):
+        raise ShredError(_("Something happened in your event after the export, please try again."))
+
+    for s in indexdata['shredders']:
+        shredder = known_shredders.get(s)
+        if not shredder:
+            continue
+
+        shredder.shred_data()
+
+    cf.file.delete(save=False)
+    cf.delete()