fix: Wrap weasyprint to catch exceptions (#6728)

* fix: Wrap weasyprint to catch exceptions (#6324)

* test: Restore socket function after test

* test: Use mock instead of monkeying with sockets

* refactor: Log the error

* fix: Don't catch non-Exception interruptions

---------

Co-authored-by: Robert Sparks <[email protected]>

ietf/doc/models.py

@@ -634,6 +634,9 @@ def pdfized(self):
                 )
             except AssertionError:
                 pdf = None
+            except Exception as e:
+                log.log('weasyprint failed:'+str(e))
+                raise
             if pdf:
                 cache.set(cache_key, pdf, settings.PDFIZER_CACHE_TIME)
         return pdf

ietf/doc/tests.py

@@ -31,6 +31,8 @@
 
 from tastypie.test import ResourceTestCaseMixin
 
+from weasyprint.urls import URLFetchingError
+
 import debug                            # pyflakes:ignore
 
 from ietf.doc.models import ( Document, DocRelationshipName, RelatedDocument, State,
@@ -2867,6 +2869,12 @@ def test_pdfized(self):
                 self.should_succeed(dict(name=draft.name,rev=f'{r:02d}',ext=ext))
         self.should_404(dict(name=draft.name,rev='02'))
 
+        with mock.patch('ietf.doc.models.DocumentInfo.pdfized', side_effect=URLFetchingError):
+            url = urlreverse(self.view, kwargs=dict(name=rfc.name))
+            r = self.client.get(url)
+            self.assertEqual(r.status_code, 200)
+            self.assertContains(r, "Error while rendering PDF")
+
 class NotifyValidationTests(TestCase):
     def test_notify_validation(self):
         valid_values = [

ietf/doc/views_doc.py

@@ -51,7 +51,6 @@
 from django import forms
 from django.contrib.staticfiles import finders
 
-
 import debug                            # pyflakes:ignore
 
 from ietf.doc.models import ( Document, DocHistory, DocEvent, BallotDocEvent, BallotType,
@@ -1064,7 +1063,10 @@ def document_pdfized(request, name, rev=None, ext=None):
     if not os.path.exists(doc.get_file_name()):
         raise Http404("File not found: %s" % doc.get_file_name())
 
-    pdf = doc.pdfized()
+    try:
+        pdf = doc.pdfized()
+    except Exception:
+        return render(request, "doc/weasyprint_failed.html")
     if pdf:
         return HttpResponse(pdf,content_type='application/pdf')
     else:

ietf/templates/doc/weasyprint_failed.html

@@ -0,0 +1,17 @@
+{# Copyright The IETF Trust 2023, All Rights Reserved #}
+{% extends "base.html" %}
+{% load origin %}
+{% block title %}Error while rendering PDF{% endblock %}
+{% block content %}
+    {% origin %}
+    <h1>Error while rendering PDF</h1>
+    <p>
+        An error was encountered while trying to render your document as PDF.
+	In case this was a temporary error, you may want to try again in a
+        little while.
+    </p>
+    <p>
+        A failure report with details about what happened has been sent to the
+        server administrators.
+    </p>
+{% endblock %}